TW202501763A - Lead frame material and manufacturing method thereof, and semiconductor package - Google Patents

Abstract

The present invention provides a lead frame material and a manufacturing method thereof, and a semiconductor package using the lead frame material. The lead frame material can improve the airtightness of the package and is less likely to cause powder shedding even in a thermal cycle predicted to be an extreme use environment. The lead frame material 1 has a conductive substrate 2, a surface coating 3 and a side coating 4. The surface coating 3 is formed on one or both of a surface 21 and a back surface 22 of at least a portion of the substrate 2. The side coating 4 is adjacent to the surface coating 3 and is formed on a side surface 23 of at least a portion of the substrate 2. The surface coating 3 and the side coating 4 both have roughened upper surfaces 30 and 40. When the average roughness height of the surface coating 3 is set to _h1 and the average roughness height of the side coating 4 is set to _h2 , the ratio of the average roughness height _h2 of the side coating 4 to the average roughness height _h1 of the surface coating 3 is _h2 / _h1 , which is greater than 1.35.

Description

Lead frame material and manufacturing method thereof, and semiconductor package

The present invention relates to a lead frame material, a method for manufacturing the same, and a semiconductor package. More specifically, the present invention relates to a lead frame material, a method for manufacturing the same, and a semiconductor package made using the lead frame material. The lead frame material has a coating (e.g., electroplating coating) on the surface and side of a conductive substrate, the coating having a specific shape, and electrically connecting semiconductor elements to each other in a resin-sealed semiconductor device.

Many resin-sealed semiconductor devices are installed in electronic and electrical equipment. These resin-sealed semiconductor devices are made by sealing semiconductor elements and lead frame materials electrically connected to each other by wires with a die-cast resin. In these resin-sealed semiconductor devices, in order to give the lead frame materials functions such as bonding, heat resistance, and sealing, they are often coated with gold (Au), silver (Ag), tin (Sn), etc.

In recent years, in order to simplify the assembly process and reduce costs, a lead frame material (pre-plated lead frame) is used, in which a coating (for example, nickel/palladium/gold (Ni/Pd/Au)) is pre-applied on the surface of the lead frame material to improve the wettability with solder when mounting on a printed circuit board by soldering, etc. (for example, refer to patent document 1).

Furthermore, in order to improve the adhesion between the lead frame material and the molding resin in the resin-sealed semiconductor device, a technique has been proposed for forming a coating composed of a roughened coating layer on the surface or side of the lead frame material (for example, see Patent Document 2 and Patent Document 3).

These technologies for roughening the coating layer are expected to achieve the following effects: (1) increasing the bonding area between the lead frame material and the die-casting resin, and (2) making it easier for the die-casting resin to bite into the roughened coating surface (i.e., anchoring effect).

By doing so, the adhesion of the mold resin to the lead frame material is improved, and the lead frame material and the mold resin are prevented from peeling off, thereby improving the reliability of the resin-sealed semiconductor device. (Prior technical literature) (Patent literature)

Patent document 1: Japanese Patent No. 2543619 Patent document 2: Japanese Patent No. 6736719 Patent document 3: Japanese Patent No. 6479265

[Problem to be solved by the invention] By roughening the coating surface as described above, the resin adhesion of the lead frame material has indeed improved compared to the past. However, with the recent demand for smaller and lower-profile semiconductor packages, it is expected that the pass level of the airtightness of the package will become more stringent. For example, it is known that when a thermal cycle test is performed with a preset extreme use environment, such as a cycle of keeping at -50°C for 30 minutes and then keeping at 105°C for 30 minutes, a gap is generated between the resin and the lead frame, and the airtightness of the package is reduced, which causes a defect. This is believed to be due to the following reasons: smaller QFN (Quad Flat Non-Leaded Package) and SOP (Small Outline Package) packages, which were not widely used before, have become widely used. In addition to the reduction in the bonding area between the mold resin and the lead frame material, the temperature load caused by the use environment in automotive applications has also increased. In particular, the reduction in the airtightness of the package due to the gap between the lead frame material and the mold resin on the side of the lead frame material has become significant. It can be seen that there is still room for improvement in the airtightness of the package.

In particular, in Patent Document 1, an Au plating film with a thickness of 0.001 μm to 0.1 μm is formed on a Pd or Pd alloy film on which an outer lead is formed on a lead frame, thereby improving the packaging characteristics of the lead frame. However, the lead frame material has low adhesion to the die-casting resin, so that peeling easily occurs at the interface with the die-casting resin. In addition, in Patent Document 2, the crystal orientation of at least the upper surface or the side surface of the lead frame material is controlled to form a needle-shaped protrusion group, thereby improving the adhesion between the lead frame material and the die-casting resin. However, in a high temperature environment or an environment where a thermal shock is applied, peeling of the die-casting resin from the smaller side surface of the bonding area with the die-casting resin easily occurs. Furthermore, in Patent Document 3, with respect to the protrusions of the roughened particles, the maximum width when measured in a cross section in the thickness direction of the roughened coating is set to a shape that is 1 to 5 times the minimum width when measured at a lower portion closer to the conductive substrate than the measurement position of the maximum width, thereby improving the adhesion to the molding resin. However, further improvement is still sought with respect to the airtightness of the package in an environment predicted to be used in a more extreme manner.

In addition, if the roughness of the entire surface of the lead frame material is increased in order to further improve the adhesion with the die-casting resin, the roughened layer tends to partially fall off on the surface and back of the lead frame material, which is called powder falling. If powder falling from the roughened layer occurs, the resistance when the die-casting resin is injected into the mold will increase, and the wettability of the die-casting resin to the lead frame material will decrease, which will cause the productivity to decrease when the lead frame material is sealed with the die-casting resin. Therefore, it is desired that powder falling on the surface and back of the lead frame material is not easy to occur.

The purpose of the present invention is to provide a lead frame material and a method for manufacturing the same, as well as a semiconductor package using the lead frame material, wherein the lead frame material can improve the airtightness of the package and is less likely to cause powder shedding even in a thermal cycle predicted to be an extreme use environment. [Technical means for solving the problem]

As a result of the research on the above-mentioned conventional technical problems, the inventors have confirmed the following viewpoint: focusing on controlling the average roughness height of the surface coating and the side coating in a lead frame material having a surface coating and a side coating, the adhesion with the resin after the heat cycle is changed, thereby changing the airtightness of the package body. The surface coating is formed on one or both of the surface and the back surface of at least a part of the substrate, and the side coating is adjacent to the surface coating and formed on the side surface of at least a part of the substrate. In particular, when the average roughness height of the surface coating is set to _h1 and the average roughness height of the side coating is set to _h2 , the ratio of the average roughness height _h2 of the side coating to the average roughness height _h1 of the surface coating is set to _h2 /h By setting ₁ to 1.35 or more, a lead frame material can be obtained which is less likely to cause powder shedding and has high adhesion to the resin even in a thermal cycle that is expected to be an extreme use environment, thereby improving the airtightness of the package. The present invention was completed based on this finding.

In order to achieve the above-mentioned object, the main structure of the present invention is as follows. (1) A lead frame material comprising: a conductive substrate; a surface coating formed on one or both of the surface and the back of at least a portion of the substrate; and a side coating adjacent to the surface coating and formed on the side of at least a portion of the substrate; in the lead frame material, the surface coating and the side coating both have a roughened upper surface, and when the average roughness height of the surface coating is set to _h1 and the average roughness height of the side coating is set to _h2 , the ratio of the average roughness height _h2 of the side coating to the average roughness height _h1 of the surface coating is _h2 / _h1 of 1.35 or more. (2) The lead frame material as described in (1) above, wherein the average roughness height _h1 of the surface coating is in the range of 0.5 μm to 3.5 μm, and the average roughness height _h2 of the side coating is in the range of 1.0 μm to 6.5 μm. (3) A lead frame material as described in (1) or (2) above, wherein, when observing the cross section of the surface coating, a first porosity in a first measurement area divided by an imaginary line _l1 and an imaginary line _n1 is set to _V1 , the imaginary line _l1 is drawn through the highest point of the upper surface of the surface coating and parallel to the surface of the substrate, and the imaginary line n1 is drawn through the lowest point of the upper surface of the surface coating and parallel to the surface of the substrate, and when observing the cross section of the side coating, a second porosity in a second measurement area divided by an imaginary line l2 and an imaginary line n2 is set to V2, the imaginary line _l1 is drawn through the highest point of the upper surface of the surface coating and parallel to the surface of the substrate, and the imaginary line _n1 is drawn through the lowest point of the upper surface of the surface coating and parallel to the surface of the substrate, and the imaginary line _l2 is drawn through the lowest point of the upper surface of the surface coating and parallel to the surface of the substrate, and the imaginary line _n2 ... ₂ is drawn through the highest point of the upper surface of the side coating and in parallel with the side surface of the substrate, and the imaginary line _n2 is drawn through the lowest point of the upper surface of the side coating and in parallel with the side surface of the substrate, and at this time, the ratio _V2 / _V1 of the second porosity _V2 to the first porosity _V1 is in the range of 0.50 to 0.91. (4) The lead frame material as described in (3) above, wherein the first porosity _V1 and the second porosity _V2 are both in the range of 32% to 64%. (5) The lead frame material as described in any one of (1) to (4) above, wherein the substrate is composed of copper, copper alloy, iron, iron alloy, aluminum or aluminum alloy. (6) A lead frame material as described in any one of (1) to (5) above, wherein, when the thickness of the substrate is set to T, the ratio of the thickness T of the substrate to the average roughness height _h2 of the side coating (T/h2 _ratio ) is in the range of greater than 15.0 and less than 200.0. (7) A lead frame material as described in any one of (1) to (6) above, wherein both the surface coating and the side coating have a roughening layer. (8) A lead frame material as described in (7) above, wherein the roughening layer is composed of copper, copper alloy, nickel or nickel alloy. (9) A lead frame material as described in (7) or (8) above, wherein the roughening layer is an electroplated coating. (10) A lead frame material as described in any one of (7) to (9) above, wherein the surface coating and the side coating further have at least one surface coating layer formed on the upper surface of the roughened layer. (11) A lead frame material as described in (10) above, wherein the surface coating layer is composed of a metal or alloy having a composition different from that of the roughened layer, and the metal or alloy is: copper, copper alloy, nickel, nickel alloy, cobalt, cobalt alloy, palladium, palladium alloy, rhodium, rhodium alloy, ruthenium, ruthenium alloy, platinum, platinum alloy, iridium, iridium alloy, gold, gold alloy, silver, silver alloy, tin, tin alloy, indium or indium alloy. (12) A method for manufacturing a lead frame material, which is a method for manufacturing a lead frame material as described in any one of (1) to (11) above, the method comprising a coating forming step, wherein the surface coating and the side coating are formed on the substrate by electroplating. (13) A semiconductor package having a lead frame, the lead frame being formed using the lead frame material as described in any one of (1) to (11) above. [Effect of the Invention]

According to the present invention, a lead frame material and a method for manufacturing the same, as well as a semiconductor package using the lead frame material can be provided. The lead frame material can improve the airtightness of the package and is less likely to cause powder shedding even in a thermal cycle that is expected to be an extreme usage environment.

The lead frame material and its manufacturing method, as well as the preferred embodiments of the semiconductor package of the present invention are described in detail below.

<For lead frame material> FIG. 1 is a cross-sectional view showing an outline of a lead frame material of an embodiment of the present invention. As shown in FIG. 1, the lead frame material 1 of the present invention has a conductive substrate 2, a surface coating 3, and a side coating 4. The surface coating 3 is formed on one or both of the surface 21 and the back surface 22 of at least a portion of the substrate 2. The side coating 4 is adjacent to the surface coating 3 and formed on the side surface 23 of at least a portion of the substrate 2. The surface coating 3 and the side coating 4 both have roughened upper surfaces 30 and 40. In the lead frame material 1, when the average roughness height of the surface coating 3 is set to _h1 and the average roughness height of the side coating 4 is set to _h2 , the ratio of the average roughness height _h2 of the side coating 4 to the average roughness height _h1 of the surface coating 3 is _h2 / _h1, which is 1.35 or more.

In this way, the adhesion between the lead frame material 1 and the resin and the airtightness of the package can be changed by controlling the average roughness heights _h1 and _h2 of the surface film 3 and the side film 4. In particular, by making the average roughness height _h2 of the side film 4 relatively larger than the average roughness height _h1 , the adhesion between the side film 4 and the mold resin, which has a small contact area with the mold resin and has low adhesion, can be relatively higher than the adhesion between the surface film 3 and the mold resin, thereby improving the airtightness of the package. If the average roughness height _h1 of the surface film 3 increases, powder falling from the surface film 3 becomes more likely to occur. Therefore, by setting the average roughness height _h2 of the side film 4 relatively larger than the average roughness height _h1 of the surface film 3, powder falling can be less likely to occur.

Therefore, by setting the ratio h ₂ /h ₁ of the average roughness height h ₂ of the side coating 4 to the average roughness height h ₁ of the surface coating 3 to 1.35 or more, a lead frame material can be obtained that can improve the airtightness of the package even in a thermal cycle that is expected to be an extreme use environment. In addition, the lead frame material 1 of the present invention in which the ratio h ₂ /h ₁ of the average roughness height h ₂ of the side coating 4 to the average roughness height h ₁ of the surface coating 3 is 1.35 or more is also excellent in that powder shedding is not likely to occur.

Here, the control of the average roughness heights _h1 and _h2 of the surface coating 3 and the side coating 4 can be implemented, for example, in the following manner: while forming the roughened layer 5 of the surface coating 3 and the side coating 4 by electroplating (roughening coating), a shielding plate is placed between the surface 21 of the substrate 2 and the counter electrode when the electroplating (roughening coating) is performed, and while adjusting the opening ratio of the shielding plate, the current density is adjusted to a range of more than 5 A/ ^dm2 and ^less than 80 A/dm2.

(For conductive substrates (substrates)) The lead frame material 1 of the present invention has a conductive substrate 2, a surface coating 3 and a side coating 4, wherein the surface coating 3 is formed on one or both of the surface 21 and the back surface 22 of at least a portion of the substrate 2, and the side coating 4 is adjacent to the surface coating 3 and formed on the side 23 of at least a portion of the substrate 2.

The substrate 2 is preferably made of a metal or alloy including copper (Cu), iron (Fe) or aluminum (Al). More specifically, from the perspective of improving electrical conductivity and heat dissipation, the substrate 2 is preferably made of copper, copper alloy, iron, iron alloy, aluminum or aluminum alloy.

When the substrate 2 is composed of an alloy, the alloy composition is not particularly limited and can be appropriately selected according to the characteristics required of the lead frame material. Here, as examples of copper alloys constituting the substrate 2, in addition to pure copper (oxygen-free copper (OFC): C1020 or tantalum copper (TPC): C1100, etc.), alloys listed in the Copper Development Association (CDA), namely C18045 (Cu-0.3Cr-0.25Sn-0.52Zn) and C19400 (Cu-2.3Fe-0.03P-0.15Zn) can be listed. In addition, as an example of an iron alloy constituting the substrate 2, 42 alloy (Fe-42Ni) can be listed. Furthermore, the number before each element represents the content in the alloy in mass %.

The substrate 2 is preferably in the form of a metal foil or an alloy foil, and examples of such metal foil or alloy foil include rolled foil and electrolytic foil. In particular, from the viewpoint of having anisotropic mechanical properties, a rolled foil formed by a stamping process or the like can be used as the substrate 2.

The thickness of the substrate 2 is not particularly limited, and is, for example, in the range of 1 μm to 500 μm, preferably in the range of 5 μm to 200 μm.

(For surface coating and side coating) The surface coating 3 is a coating formed on one or both of the surface 21 and the back surface 22 of at least a portion of the substrate 2. In addition, the side coating 4 is a coating adjacent to the surface coating 3 and formed on the side 23 of at least a portion of the substrate 2. Therefore, the lead frame material 1 of the present invention is a substrate 2, a surface coating 3, and a side coating 4 having the above-mentioned conductivity.

The surface coating 3 and the side coating 4 both have roughened upper surfaces 30 and 40, and when the average roughness height of the upper surface 30 of the surface coating 3 is set to _h1 and the average roughness height of the upper surface 40 of the side coating 4 is set to _h2 , the ratio of the average roughness height _h2 of the side coating 4 to the average roughness height _h1 of the surface coating 3 is _h2 / _h1 or more, which is 1.35. Thus, the roughness of the side coating 4 formed on the side surface 23 of the substrate 2 is greater than that of the surface coating 3 formed on the surface 21 and the back surface 22 of the substrate 2, and therefore, it becomes difficult to generate a gap between the side coating 4 and the resin (molding resin) at the side surface 23 of the substrate 2. Furthermore, by setting the ratio h ₂ /h ₁ of the average roughness height h ₂ of the side coating 4 to the average roughness height h ₁ of the surface coating 3 to be 1.35 or more, it is possible to prevent powder from falling off the upper surface 30 of the surface coating 3. On the other hand, if the ratio h ₂ /h 1 of the average roughness height h ₂ of the side coating 4 to the average roughness height h ₁ of the surface coating ₃ is less than 1.35, the adhesion between the side coating 4 and the resin is greatly reduced compared to the adhesion between the surface coating 3 and the resin, so that a gap is easily generated between the side surface 23 of the substrate 2 and the resin during a thermal cycle, and the airtightness of the package is reduced. Therefore, from the viewpoint of further improving the airtightness of the package, the ratio h ₂ /h ₁ of the average roughness height h ₂ of the side film 4 to the average roughness height h ₁ of the surface film 3 is preferably in the range of 1.35 to 5.00, more preferably 1.66 to 5.00.

Here, the average roughness height _h1 of the surface coating 3 is preferably in the range of 0.5 μm or more and 3.5 μm or less, and more preferably in the range of 0.8 μm or more and 2.5 μm or less. In particular, from the viewpoint of improving the adhesion between the surface coating 3 and the resin and further improving the airtightness of the package, the average roughness height _h1 of the surface coating 3 is preferably 0.5 μm or more, and more preferably 0.8 μm or more. In addition, from the viewpoint of improving the adhesion between the surface coating 3 and the substrate 2 and making it difficult for the powder of the lead frame material 1 to fall off, the average roughness height _h1 of the surface coating 3 is preferably 3.5 μm or less, and more preferably 2.5 μm or less.

In addition, the average roughness height _h2 of the side coating 4 is preferably in the range of 1.0 μm or more and 6.5 μm or less, and more preferably in the range of 1.2 μm or more and 4.8 μm or less. In particular, from the viewpoint of improving the adhesion between the side coating 4 and the resin and further improving the airtightness of the package, the average roughness height _h2 of the side coating 4 is preferably 1.0 μm or more, more preferably 1.2 μm or more, and further preferably 1.5 μm or more. In addition, from the viewpoint of improving the adhesion between the side coating 4 and the substrate 2 and making it difficult for the lead frame material 1 to fall off, the average roughness height _h2 of the side coating 4 is preferably 6.5 μm or less, and more preferably 4.8 μm or less.

The average roughness height _h1 of the surface coating 3 and the average roughness height _h2 of the side coating 4 can be obtained by micro-slicing a cross section in the thickness direction including the surface coating 3 and the side coating 4 and observing using a scanning electron microscope (SEM). Here, in the observation by SEM, a total of 10 continuous concavities and convexities on the coating are regarded as one field of view, and then three fields of view are randomly selected. For the SEM images of the total of three fields of view, the plane of the surface (or back surface, side surface) of the substrate 2 passing through the highest point of the concavity and convexity (the highest point of the upper surface of the surface coating) is respectively used. An evaluation area (evaluation area M1 of the surface coating 3 or evaluation area M2 of the side coating 4) is divided by an imaginary line drawn in parallel with the surface (or back side, side) of the substrate 2 passing through the lowest point of the unevenness (the lowest point of the upper surface of the surface coating). In the evaluation area, the area occupied by the surface coating 3 or the side coating 4 (the existence area P1 of the surface coating 3, the existence area P2 of the side coating 4) can be calculated. The calculation of the area occupied by the surface coating 3 or the side coating 4 can be performed by binarization using the image processing software Image J, with the lower threshold set to 128 and the upper threshold set to 255. The separation points are excluded by the binarization settings, while the inside of the area where the surface coating 3 and the side coating 4 exist is colored. The value obtained by dividing the area occupied by the surface coating 3 or the side coating 4 obtained at this time by the length of the entire line (the width of 10 bumps) can be set as the average roughness height of the coating (surface coating 3 or side coating 4) in each field of view.

For example, as shown in FIG. 2, when the area of the surface film 3 formed on the surface 21 of the substrate 2 is to be calculated, an imaginary line _l1 drawn parallel to the surface 21 passing through the highest point A1 of the upper surface 30 of the surface film 3 and an imaginary line _n1 drawn parallel to the surface 21 passing through the lowest point B1 of the upper surface 30 of the surface film 3 are drawn in each field of view. At this time, as shown in FIG. 3, the area divided by the imaginary line _l1 and the imaginary line _n1 is set as the evaluation area M1, and the area of the portion of the evaluation area M1 occupied by the surface film 3 is calculated, that is, the area of the surface film 3 existing area P1 occupied in the evaluation area M1 on the surface 21 can be calculated. When the area of the surface film 3 formed on the back side 22 of the substrate 2 is to be calculated, the same operation is performed, that is, the area of the surface film 3 existing area P1 occupied in the evaluation area M1 on the back side 22 can be calculated. The value obtained by dividing the area of the surface film 3 existing area P1 obtained at this time by the length of the entire line (the width of 10 concavities) L1 can be set as the average roughness height of the surface film 3 in each field of view. Here, when the surface film 3 is formed on both the surface 21 and the back side 22 of the substrate 2, the average roughness height of the surface film 3 in a total of 6 fields of view, namely, 3 fields of view on the surface 21 side and 3 fields of view on the back side 22 side, can be averaged to set as the average roughness height h ₁ of the surface film 3. When the surface film 3 is formed on one of the surface 21 or the back surface 22 of the substrate 2 , the average roughness heights of the surface film 3 in three viewing fields on the side where the surface film 3 is formed can be averaged to obtain the average roughness height h ₁ of the surface film 3 .

Furthermore, as shown in FIG. 4, when the area of the side coating 4 formed on the side surface 23 of the substrate 2 is to be calculated, an imaginary line _l2 drawn parallel to the side surface 23 passing through the highest point A2 of the upper surface 40 of the side coating 4 and an imaginary line _n2 drawn parallel to the side surface 23 passing through the lowest point B2 of the upper surface of the side coating 4 are drawn in each field of view. At this time, as shown in FIG. 5, the area divided by the imaginary line _l2 and the imaginary line _n2 is set as the evaluation area M2, and the area of the existence area P2 of the side coating 4 occupied in the evaluation area M2 is calculated, that is, the area of the existence area P2 of the side coating 4 occupied in the evaluation area M2 on the side surface 23 can be calculated. The value obtained by dividing the area of the area P2 where the side coating 4 exists by the length of the entire line (the width of 10 concavities) L2 can be set as the average roughness height of the side coating 4 in each field of view. Furthermore, the average roughness height of the side coating 4 in a total of three fields of view where the side coating 4 is formed can be averaged to obtain the average roughness height _h2 of the side coating 4.

Furthermore, FIG. 2 is a cross-sectional view showing a surface coating 3 formed on a surface 21 of a substrate 2 in a lead frame material 1 having the same structure as FIG. 1, but in order to explain the area P1 where the surface coating exists, for the sake of convenience, different hatching is applied to a portion of the surface coating 3 included in the evaluation area M1 (a portion included in the area P1 where the surface coating exists) and a portion not included in the evaluation area M1 (a portion not included in the area P1 where the surface coating exists occupied by the evaluation area M1). Similarly, FIG. 4 is a cross-sectional view showing the side coating 4 formed on the side surface 23 of the substrate 2 in the lead frame material 1 having the same structure as FIG. 1, but in order to explain the area P2 where the surface coating exists, different hatching is applied to the portion of the side coating 4 included in the evaluation area M2 and the portion not included in the evaluation area M2 for the sake of convenience.

On the other hand, it is preferred that: in cross-sectional observation of the surface coating 3, a first porosity in a first measurement area (e.g., the area of the evaluation area M1 described above) divided by an imaginary line _l1 and an imaginary line _n1 is set to _V1 , wherein the imaginary line _l1 is drawn through the highest point A1 of the upper surface 30 of the surface coating 3 and is parallel to the surface 21 (or the back surface 22) of the substrate 2, and the imaginary line _n1 is drawn through the lowest point B1 of the upper surface 30 of the surface coating 3 and is parallel to the surface 21 of the substrate 2; and in cross-sectional observation of the side coating 4, a second porosity in a second measurement area (e.g., the area of the evaluation area M2 described above) divided by an imaginary line _l2 and an imaginary line _n2 is set to _V2 , and the imaginary line l1 is drawn through the highest point A1 of the upper surface 30 of the surface coating 3 and is parallel to the surface 21 of the substrate 2. ₂ is drawn in a manner passing through the highest point A2 of the upper surface 40 of the side coating 4 and being parallel to the side surface 23 of the substrate 2, and the imaginary line _n2 is drawn in a manner passing through the lowest point B2 of the upper surface 40 of the side coating 4 and being parallel to the side surface 23 of the substrate 2. At this time, the ratio _V2 / _V1 of the second porosity _V2 to the porosity _V1 is in the range of not less than 0.50 and not more than 0.91. Here, if V ₂ /V ₁ is less than 0.50, the side surface 23 becomes less adhesive to the resin than the front surface 21 and the back surface 22. Therefore, in the case of a thermal cycle in an environment of use that is expected to be extreme, the airtightness of the package sealed with the resin is reduced compared to the case where V ₂ /V ₁ is greater than 0.50, and the heat cycle resistance is reduced. On the other hand, if _V2 / _V1 is greater than 0.91, the resin fills less into the unevenness of the upper surface 40 of the side cover 4, and it becomes difficult to obtain the anchoring effect. Therefore, in the case of a heat cycle in an environment of use that is expected to be extreme, the adhesion of the resin to the lead frame material 1 is reduced compared to the case where _V2 / _V1 is less than 0.91, and the airtightness of the package is reduced, so the heat cycle resistance is reduced. Therefore, the ratio _V2 / _V1 of the second void ratio _V2 to the void ratio _V1 is preferably in the range of 0.50 or more and 0.91 or less, and more preferably in the range of 0.62 or more and 0.83 or less.

Here, the thermal expansion coefficients of the resin and the lead frame material 1 are different, and the volume change of the resin due to heat is larger than that of the lead frame material 1. Therefore, it is preferable to control the ratio of the space filled with the resin at the portion where the resin and the lead frame material 1 are in contact, that is, the porosity of the surface coating 3 and the side coating 4 of the lead frame material 1 within an appropriate range. More specifically, the first porosity _V1 and the second porosity _V2 are preferably both within a range of 32% or more and 64% or less. If at least one of the first porosity _V1 and the second porosity _V2 is less than 32%, it becomes difficult for the resin to fill the unevenness of the upper surface 30, 40 of the surface coating 3 or the side coating 4. Therefore, compared with the case where the porosity is greater than 32%, there is a concern that a gap will be generated between the lead frame material 1 and the resin, thereby reducing the adhesion. Furthermore, if at least one of the first porosity _V1 and the second porosity _V2 is less than 32%, there is a concern that the lead frame material 1 cannot follow the expansion and contraction of the resin. Therefore, in the case of a thermal cycle in an environment that is expected to be an extreme use environment, the resin is more likely to be peeled off from the lead frame material 1 than when the porosity is greater than 32%, thereby reducing the adhesion and the airtightness of the package, thereby reducing the heat cycle resistance. On the other hand, if at least one of the first porosity _V1 and the second porosity _V2 is greater than 64%, it becomes difficult to obtain an anchoring effect with the resin, and therefore, there is a concern that the adhesion of the lead frame material 1 to the resin is reduced compared to the case where the porosity is 64% or less. In addition, if at least one of the first porosity _V1 and the second porosity _V2 is greater than 64%, when the resin expands by heating, the pressure applied by the resin to the surface film 3 and the side film 4 increases, and therefore, when this step is repeated by heat cycle, the surface film 3 and the side film 4 are damaged and gaps are easily generated. Therefore, compared with the case where the porosity is below 64%, the adhesion to the resin is reduced and the airtightness of the package is reduced, so the heat cycle resistance is reduced. Therefore, the first porosity _V1 is preferably in the range of 32% to 64%, more preferably in the range of 45% to 60%. In addition, the second porosity _V2 is preferably in the range of 32% to 64%, more preferably in the range of 32% to 52%, and further preferably in the range of 35% to 50%.

The first porosity _V1 and the second porosity _V2 can be calculated using SEM images for measuring the average roughness height _h1 of the surface film 3 and the average roughness height _h2 of the side film 4. The ratio of the void area obtained by subtracting the area of the film portion P from the area of the evaluation areas M1 and M2 to the overall area of the evaluation areas M1 and M2 can be calculated for the surface film 3 formed on the surface 21, the surface film 3 formed on the back surface 22, and the side film 4 formed on the side surface 23, thereby determining the porosity of each field of view.

Based on the porosity of each field of view, in an example where the surface coating 3 is formed on both the surface 21 and the back surface 22 of the substrate 2, the porosity of the surface coating 3 in a total of 6 fields of view, which is a total of 3 fields of view on the surface 21 side and a total of 3 fields of view on the back surface 22 side, is averaged to be set as the first porosity V ₁ (%). In addition, in an example where the surface coating 3 is formed on one of the surface 21 or the back surface 22 of the substrate 2, the porosity of the surface coating 3 in a total of 3 fields of view on the side where the surface coating 3 is formed is averaged to be set as the first porosity V _1. In addition, for the side coating 4, the porosity of a total of 3 fields of view can also be averaged to be set as the second porosity V ₂ (%).

In the lead frame material 1 of the present invention, when the thickness of the substrate 2 is set to T, the ratio of the thickness T of the substrate 2 to the average roughness height _h2 of the side coating 4 (T/ _h2 ratio) is preferably in the range of 15.0 or more and 200.0 or less. In particular, if the T/h2 _ratio is less than 15.0, the roughness height of the side coating 4 becomes excessively large relative to the area of the side surface 23 of the substrate 2, and thus powder shedding is more likely to occur than when the T/ _h2 ratio is greater than 15.0. If the T/ _h2 ratio is greater than 200.0, the roughness height of the side coating 4 becomes low relative to the area of the side surface 23, and thus it becomes difficult to obtain adhesion with the resin than when the T/h2 _ratio is less than 200.0. Therefore, the ratio of the thickness T of the substrate 2 to the average roughness height _h2 of the side coating 4 (T/ _h2 ratio) is preferably in the range of 15.0 to 200.0, and more preferably in the range of 20.0 to 125.0.

When the lead frame material 1 of the present invention does not have a surface coating layer 6 described later, as shown in FIG. 1 , the surface coating 3 and the side coating 4 can be formed by the roughening layer 5, respectively. On the other hand, when the lead frame material 1A has a surface coating layer 6 described later, as shown in FIG. 6 , the coating having the surface coating layer 6 among the surface coating 3A and the side coating 4A is formed by the roughening layer 5 and the surface coating layer 6. Here, the surface coating 3 (3A) and the side coating 4 (4A) preferably both have the roughening layer 5.

The rough layer 5 is formed on at least a portion of the surface of the substrate 2. The rough layer 5 is formed by attaching roughening particles to the surface 21, the back surface 22 or the side surface 23 of the substrate 2.

Roughened layer 5 is preferably made of a metal or alloy containing at least one element of copper (Cu) and nickel (Ni). More specifically, from the viewpoint of forming a roughened shape with excellent adhesion to the resin, roughened layer 5 is preferably made of copper, a copper alloy, nickel or a nickel alloy.

In addition, the roughened layer 5 can be formed by, for example, electroplating, Focus Ion Beam (FIB) or mechanical polishing. Among them, the roughened layer 5 is preferably formed by electroplating as an electroplated coating.

(Surface coating layer) As shown in the lead frame material 1A of FIG. 6 , the surface coating 3A and the side coating 4A preferably further have at least one surface coating layer 6 formed on the upper surface 50 of the roughened layer 5. At this time, the surface coating 3A and the side coating 4A to be measured for the average roughness height h ₁ of the surface coating 3 and the average roughness height h ₂ of the side coating 4 have the roughened layer 5 and the surface coating layer 6 formed on at least the surface of the roughened layer. By providing such a surface coating layer 6, the surface properties of the roughened layer 5 improve the adhesion to the resin and the surface composition of the lead frame material 1A is changed. Therefore, the wettability to the solder and the adhesion to the resin can be improved while the adhesion to the base 2 is improved.

The presence or absence of the surface coating layer 6 and the number of the surface coating layers 6 can be appropriately selected according to the application of the lead frame material.

Here, it is preferred that at least one layer of the surface coating layer 6 is composed of a metal or alloy having a composition different from that of the roughened layer 5. More specifically, it is preferred that at least one layer of the surface coating layer 6 is composed of one or more metals or alloys selected from the group consisting of copper (Cu), nickel (Ni), cobalt (Co), palladium (Pd), rhodium (Rh), ruthenium (Ru), platinum (Pt), iridium (Ir), gold (Au), silver (Ag), tin (Sn) and indium (In). More specifically, it is preferred that at least one layer of the surface coating layer 6 is composed of copper, copper alloy, nickel, nickel alloy, cobalt, cobalt alloy, palladium, palladium alloy, rhodium, rhodium alloy, ruthenium, ruthenium alloy, platinum, platinum alloy, iridium, iridium alloy, gold, gold alloy, silver, silver alloy, tin, tin alloy, indium or indium alloy.

In particular, the surface coating layer 6 is the surface in contact with the outside of the lead frame material 1A, and preferably has excellent wettability with solder or the like. Therefore, the surface coating layer 6 is preferably composed of a metal or alloy containing one or more elements selected from the group consisting of gold (Au), silver (Ag), copper (Cu) and tin (Sn). In particular, from the viewpoint of improving wettability with solder, the surface coating layer 6 is preferably composed of a gold-cobalt alloy, gold, silver, copper or tin.

The thickness of the surface coating layer 6 is not particularly limited. If the thickness is too large, the unevenness formed in the roughening layer 5 will be covered, and the effect of improving the adhesion of the resin may be damaged. Therefore, the thickness of the surface coating layer 6 is preferably 3.00 μm or less. In addition, when the surface coating layer 6 is composed of a metal or alloy containing a precious metal such as gold or silver, the thickness of the surface coating layer 6 is preferably 2.00 μm or less from the perspective of not increasing the material cost to a higher level than necessary. Furthermore, the thickness of the surface coating layer 6 can be measured by a film thickness meter such as a fluorescent X-ray film thickness meter.

<Manufacturing method for lead frame material> The manufacturing method for the lead frame material is not particularly limited, but from the viewpoint of improving productivity and making it easier to control the ratio _h2 / _h1 of the average roughness height _h2 of the side coating 4 to the average roughness height _h1 of the surface coating 3, preferably, a method including a coating forming step is to form the surface coating 3 and the side coating 4 having the roughened upper surfaces 30 and 40 on the substrate 2 by electroplating. As an example, a method of forming the roughened layer 5 on the substrate 2 by electroplating is preferred.

As an example of a method for manufacturing a lead frame material, the following method can be implemented: prepare a conductive substrate 2, the substrate 2 is one whose size and thickness have been adjusted in advance by stamping, perform cathode electrolytic degreasing and pickling as pretreatment, and then form a roughening layer 5. Here, as a method for forming the roughening layer, electroplating, Focus Ion Beam (FIB, focused ion beam system) or mechanical polishing can be listed. Among them, the roughening layer 5 is preferably formed by electroplating. An example of the formation conditions of the electroplating layer when a copper plating layer is formed as the roughening layer 5 is shown below.

[Electroplating coating formation conditions] Plating bath: 10 g/L to 35 g/L (copper (atom) conversion) copper sulfate 60 g/L to 180 g/L molybdenum sulfate concentration 0.1 g/L to 5.0 g/L ammonium molybdate Plating conditions: bath temperature 20℃ to 60℃, current density 30 A/dm2 ^to 80 A/ ^dm2

Here, as a method for controlling the ratio h ₂ /h ₁ of the average roughness height h ₂ of the side coating 4 of the lead frame material 1 to the average roughness height h ₁ of the surface coating 3, for example, when the roughening layer 5 is formed by electroplating (roughening coating), a shielding plate is provided between the surface 21 of the substrate 2 and the counter electrode, and the area to be shielded is adjusted to a range of not less than 10% and not more than 30% relative to the total coating area of the surface 21 and the back surface 22 of the substrate 2, and the current density is adjusted to a range of not less than 5 A/dm ² and not more than 80 A/dm ² . In this way, while adjusting the ratio of the area shielded by the shielding plate relative to the total coated area of the surface 21 and the back side 22 of the substrate 2 (the opening ratio of the shielding plate), the current density is also adjusted to a range of 5 A/ ^dm2 to 80 A/dm2, thereby obtaining a lead frame material 1 in which the ratio _h2 / ^h1 of the average roughness height _h2 of the side coating 4 to the average roughness height _h1 of the surface coating ₃ is greater than 1.35.

<Application of lead frame materials> Lead frame materials are used as connection terminals, which support and fix semiconductor components and are used to exchange electricity and signals with the outside through wires and printed circuit boards. For example, they can be used in semiconductor packages that have lead frames formed using lead frame materials. Here, as semiconductor components that can be installed in semiconductor packages, transistors, capacitors, LEDs, etc. can be listed, but they are not limited to these.

The lead frame material of the present invention can maintain good resin adhesion with respect to the lead frame material without substantially deteriorating the lead frame material even when subjected to a thermal cycle that is expected to be an extreme usage environment, and is less likely to cause failures and defects due to powder falling from the roughened layer. Therefore, high reliability can be achieved, particularly in semiconductor packages for automotive applications and the like.

The above describes the implementation form of the present invention, but the present invention is not limited to the above implementation form, but also includes all aspects within the scope of the concept of the present invention and the scope of the invention application, and can be variously modified within the scope of the present invention. [Example]

Next, in order to further clarify the effects of the present invention, examples of the present invention and comparative examples are described, but the present invention is not limited to these examples of the present invention.

(Examples 1 to 19 of the present invention, comparative examples 1 to 7) A conductive substrate 2 having a thickness as shown in Table 1 was prepared, and cathodic electrolytic degreasing and pickling were performed as pretreatment. The substrate 2 was made of the metal or alloy of the type shown in Table 1 and was previously made into a size of 30 mm in length and 10 mm in width by stamping.

Here, cathodic electrolytic degreasing is carried out in the following manner: a 60 g/L sodium hydroxide aqueous solution is poured into an electrolytic cell as a degreasing solution and heated, the substrate 2 is immersed in the degreasing solution heated to 60°C and connected to the anode of the electrolytic cell, and power is applied at a current density of 2.5 A/ ^dm2 for 60 seconds.

In addition, the acid cleaning was performed by immersing the substrate 2 after the cathodic electrolytic degreasing in 10 mass % sulfuric acid at room temperature for 30 seconds.

Thereafter, for Examples 1 to 19 of the present invention and Comparative Examples 3 to 7, a roughened layer 5 (or a Cu layer) was formed on all surfaces (the front surface, the back surface, and the side surface) of the substrate 2 by electroplating under the conditions shown below. At this time, for Example 14 of the present invention, the surface 21 of the substrate 1 was covered with an adhesive tape, thereby forming a roughened layer 5 of Cu on surfaces other than the surface 21 of the substrate 2 (the back surface 22 and the side surface 23). Furthermore, for Comparative Example 3, the surface 21 and the side surface 23 of the substrate 2 were covered with an adhesive tape, thereby forming a Cu layer only on the back surface 22 of the substrate 2, and then the Cu layer formed on the back surface 22 of the substrate 2 was roughened by bringing the Cu layer into contact with the liquid surface of the etching solution. On the other hand, in Comparative Examples 1 and 2, the surface coating 3 and the side coating 4 are not formed on the substrate 2.

[Roughening Cu coating (when the "type" of the roughening layer recorded in Table 1 is Cu)] For Examples 1, 2, 4 to 17, 19 of the present invention and Comparative Examples 4 to 7, an aqueous solution containing the following components was prepared as an electroplating solution, and 1 L of the electroplating solution was poured into a cylindrical electrolytic cell with an inner diameter of 80 mm. The components were: copper sulfate having a metal concentration in the range of 10 g/L to 50 g/L as copper (Cu) metal, sulfuric acid having a metal concentration of 60 g/L to 180 g/L, and ammonium molybdate having a metal concentration of 0.1 g/L to 5.0 g/L as molybdenum (Mo) metal. Next, for Examples 1, 2, 4 to 17, and 19 of the present invention, a shielding plate was provided between the counter electrode in such a manner that the shielding plate shielded an area of the ratio described in Table 1 relative to the total coating area of the surface 21 and the back surface 22 of the substrate 2. On the other hand, for Comparative Example 4, a shielding plate was provided between the counter electrode in such a manner that 40% of the total coating area of the surface 21 and the back surface 22 of the substrate 2 was shielded. For Comparative Examples 5 to 7, a shielding plate was provided between the counter electrode in such a manner that 5% of the total coating area of the surface 21 and the back surface 22 of the substrate 2 was shielded. Here, the film forming step is performed by passing electricity at a temperature of 20°C to 60°C and a current density of 20 A/dm ² to 80 A/dm ² , and the surface film 3 and the side film 4 are formed by electroplating.

On the other hand, for Comparative Example 3, an aqueous solution containing the following components was prepared as an electroplating solution, and 1 L of the electroplating solution was poured into a cylindrical electrolytic cell with an inner diameter of 80 mm. The components were: copper sulfate with a metal concentration of 250 g/L as copper (Cu) metal, 50 g/L sulfuric acid, and 0.1 g/L sodium chloride. At this time, no shielding plate was set between the counter electrode and the electrode. Next, after a Cu layer is formed to 10 μm by electroplating while passing an electric current at a current density of 60 A/ ^dm2 at a temperature of 40°C, the Cu layer formed on the back side 22 of the substrate 2 is brought into contact with a liquid surface of an etching solution containing 60 g/L of sulfuric acid and 40 mL/L of hydrogen peroxide at a temperature of 40°C for 30 seconds, thereby roughening the surface of the Cu layer.

[Roughening Ni coating (when the "type" of the roughening layer listed in Table 1 is Ni)] An aqueous solution containing the following components is prepared as a plating solution: nickel sulfate having a metal concentration of 10 g/L to 50 g/L as nickel (Ni) metal listed in Table 1, 10 g/L to 30 g/L of boric acid, 30 g/L to 100 g/L of sodium chloride, and 10 mL/L to 30 mL/L of 25 mass % ammonia water. Then, 1 L of the plating solution is poured into a cylindrical plating electrolytic cell having an inner diameter of 80 mm, and a shielding plate is provided between the substrate 2 and the counter electrode in such a manner that the total plating area of the surface 21 and the back surface 22 of the substrate 2 is shielded by a shielding plate in a ratio listed in Table 1. Here, the film forming step is performed by passing electricity at a temperature of 50°C to 70°C at a current density of 5 A/dm ² to 30 A/dm ² , and the surface film 3 and the side film 4 are formed by electroplating.

Next, for the present invention examples 15 to 19 and comparative examples 2, 6, and 7, the surface coating layer 6, which is the outermost layer, was formed. At this time, the surface coating layer 6 was formed on the entire upper surface 50 of the roughened layer 5 (the surface 21, the back surface 22, and the side surface 23 of the substrate 2 for comparative example 2) by electroplating under the conditions shown below so as to have the thickness shown in Table 1. In this way, the lead frame materials of the present invention examples and comparative examples were obtained.

[Ni plating (when the "type" of the surface coating layer 6 listed in Table 1 is Ni)] An aqueous solution containing the following components was prepared as a plating solution: nickel sulfonamide with a metal concentration in the range of 500 g/L as the nickel (Ni) metal concentration, 30 g/L of nickel chloride, and 30 g/L of boric acid. 1 L of the plating solution was poured into a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and current was passed at a temperature of 50°C with a current density of 10 A/ ^dm2 to form the surface coating layer 6 by electroplating.

[Pd coating (when the "type" of the surface coating layer 6 listed in Table 1 is Pd)] An aqueous solution containing the following components was prepared as a plating solution: tetraammonium dichloride palladium (Pd(NH ₃ ) ₄ Cl ₂ ) having a metal concentration in the range of 45 g/L as the palladium (Pd) metal concentration, 90 mL/L of 25 mass % ammonia water, 50 g/L of ammonium sulfate, and 10 g/L of Parasigma LN glossing agent (trade name, manufactured by Matsuda Industrial Co., Ltd.). 1 L of the plating solution was poured into a cylindrical plating electrolytic cell having an inner diameter of 80 mm, and current was passed at a temperature of 60°C and a current density of 5 A/dm ² to form the surface coating layer 6 by electroplating.

[Au plating (when the "type" of the surface coating layer 6 listed in Table 1 is Au)] An aqueous solution containing the following components was prepared as a plating solution: potassium gold cyanide with a metal concentration in the range of 14.6 g/L as the gold (Au) metal concentration, 150 g/L of citric acid, and 180 g/L of potassium citrate. 1L of the plating solution was poured into a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and current was passed at a temperature of 40°C with a current density of 1 A/ ^dm2 to form the surface coating layer 6 by electroplating.

[AuCo plating (when the "type" of the surface coating layer 6 listed in Table 1 is AuCo)] An aqueous solution containing the following components was prepared as a plating solution: potassium gold cyanide with a metal concentration in the range of 10 g/L as the gold (Au) metal concentration, cobalt carbonate with a metal concentration in the range of 0.1 g/L as the cobalt (Co) metal concentration, 100 g/L of citric acid, and 20 g/L of potassium dihydrogen phosphate. 1L of the plating solution was poured into a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and current was passed at a temperature of 40°C with a current density of 1 A/ ^dm2 to form the surface coating layer 6 by electroplating.

[Ag plating (when the "type" of the surface coating layer 6 listed in Table 1 is Ag)] An aqueous solution containing the following components was prepared as a plating solution: silver cyanide with a metal concentration in the range of 93 g/L as the concentration of silver (Ag) metal, and 132 g/L of potassium cyanide. 1L of the plating solution was poured into a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and current was passed at a temperature of 20°C with a current density of 1 A/ ^dm2 to form the surface coating layer 6 by electroplating.

[Sn plating (when the "type" of the surface coating layer 6 listed in Table 1 is Sn)] An aqueous solution containing the following components was prepared as an electroplating solution: tin sulfate having a metal concentration in the range of 80 g/L as the concentration of tin (Sn) metal, 50 mL/L of sulfuric acid, and 5 mL/L of UTB513Y. 1L of the electroplating solution was poured into a cylindrical electrolytic cell with an inner diameter of 80 mm, and current was passed at a temperature of 20°C with a current density of 5 A/ ^dm2 to form the surface coating layer 6 by electroplating.

<Various measurement and evaluation methods> Then, the characteristics of each layer and the lead frame material 1 obtained are measured and evaluated as follows. Furthermore, the characteristics of each layer obtained are measured at any time during the process of manufacturing the lead frame material 1.

[1] Measurement of Average Roughness Height _h1 of Surface Film and Average Roughness Height _h2 of Side Film The average roughness height _h1 of the surface film 3 is determined by microtome-processing a cross section including the thickness direction of the surface film 3 and observing it using a scanning electron microscope (SEM). Here, observations are made by SEM, and for the surface coating 3 formed on the surface 21 of the substrate 2 and the surface coating 3 formed on the back side 22, a total of 10 continuous bumps on the coating are regarded as one field of view, and then SEM images of a total of 3 fields of view are randomly selected. For the SEM images of a total of 3 fields of view, an evaluation area M1 is demarcated using an imaginary line drawn parallel to the surface (or back side) of the substrate 2 passing through the highest point of the bumps (the highest point of the upper surface of the coating) and an imaginary line drawn parallel to the surface (or back side) of the substrate 2 passing through the lowest point of the bumps (the lowest point of the upper surface of the coating). In the evaluation area M1, the area occupied by the surface coating 3 (the area P1 where the surface coating 3 exists) is calculated. The area of the coating part P can be calculated by binarization using the image processing software Image J. The lower threshold is set to 128 and the upper threshold is set to 255. The separation points are excluded by the binarization settings, and the inside of the coating part P is colored. The area of the coating part P1 obtained at this time is divided by the length of the entire line (the width of 10 concavities) L1 to obtain the value obtained as the average roughness height of the surface coating 3 in each field of view. Here, in the example where the surface film 3 is formed at both the surface 21 and the back surface 22 of the substrate 2, the average roughness heights of the surface film 3 in a total of 6 fields of view, which are 3 fields of view on the surface 21 side and 3 fields of view on the back surface 22 side, are averaged to be the average roughness height h ₁ of the surface film 3. In addition, in the example where the surface film 3 is formed at one of the surface 21 or the back surface 22 of the substrate 2, the average roughness heights of the surface film 3 in a total of 3 fields of view on the side where the surface film 3 is formed are averaged to be the average roughness height h ₁ of the surface film 3. The results are shown in Table 1.

In addition, the average roughness height h ₂ of the side film 4 is obtained by taking a total of 10 continuous concavities and convexities on the side film 4 formed on the side surface 23 as one field of view, and then randomly selecting a total of 3 fields of view. For the total of 3 fields of view, the area of the portion occupied by the side film 4 in the evaluation area M2 is calculated in the same manner as the measurement of the average roughness height h ₁ of the surface film 3. The value obtained by dividing the area of the coating portion P2 obtained at this time by the length of the entire line (the width of 10 concavities) L2 is obtained as the average roughness height of the side coating 4 in each field of view, and the average roughness heights of the side coating 4 in three fields of view are averaged to be set as the average roughness height _h2 of the side coating 4.

Furthermore, based on the results of the average roughness height _h1 of the surface coating 3 and the average roughness height _h2 of the side coating 4, the ratio _h2 / _h1 of the average roughness height _h2 of the side coating 4 to the average roughness height _h1 of the surface coating 3 and the ratio of the thickness T of the substrate 2 to the average roughness height _h2 of the side coating 4 (T/ _h2 ratio) were calculated. The results are shown in Table 1.

[2] Determination of the first porosity _V1 and the second porosity _V2 The first porosity _V1 is determined by using the SEM image used in the above-mentioned "[1] Determination of the average roughness height _h1 of the surface film and the average roughness height _h2 of the side film". For the surface film 3 formed on the surface 21 and the surface film 3 formed on the back surface 22, the ratio of the area of the void portion (the area S1 where the surface film 3 does not exist) obtained by subtracting the area of the area P1 where the surface film 3 exists from the area of the evaluation area M1 to the area of the entire evaluation area M1 is calculated to obtain the porosity of each field of view. That is, the porosity of the surface film 3 in each field of view is calculated by the following formula (1). Porosity of surface film 3 (%) = 100 × {(area of evaluation region M1) - (area of region P1 where surface film 3 exists)} / (area of evaluation region M1) ･･･(1) Based on the porosity of each field of view, in an example where surface film 3 is formed on both surface 21 and back surface 22 of substrate 2, the average roughness height of surface film 3 in 3 fields on surface 21 side and 3 fields on back surface 22 side, a total of 6 fields, is averaged to be the first porosity V ₁ (%). In addition, in an example where surface film 3 is formed on either surface 21 or back surface 22 of substrate 2, the porosity of surface film 3 in 3 fields on the side where surface film 3 is formed is averaged to be the first porosity V ₁ (%).

In addition, the second porosity _V2 is calculated by using the SEM image used in the above-mentioned "[1] Measurement of the average roughness height _h1 of the surface film and the average roughness height _h2 of the side film" to calculate the ratio of the area of the void portion (the area S2 where the side film 4 does not exist) to the area of the entire evaluation area M2, which is obtained by subtracting the area of the area P2 where the side film 4 exists from the area of the evaluation area M2, to obtain the porosity for each field of view. That is, the porosity of the side film 4 for each field of view is calculated by the following formula (2). Porosity of side coating 4 (%) = 100 × {(area of evaluation region M2) - (area of region P2 where side coating 4 exists)} / (area of evaluation region M2) ... (2) Based on the porosity of each field of view, the porosity of side coating 4 in three fields of view is averaged to obtain a second porosity _V2 (%).

Furthermore, based on the obtained results of the first porosity _V1 and the second porosity _V2 , the ratio V2 _{/ V1} of the second porosity _V2 to the first porosity _V1 was calculated. The results are shown in Table 1.

[3] Measurement of the thickness of the surface coating layer The thickness of the surface coating layer 6 was measured by a fluorescent X-ray test method in accordance with Japanese industrial standard JIS H8501:1999. Specifically, a fluorescent X-ray film thickness meter (SFT9400, manufactured by SII Technologies Ltd.) was used, and the collimator diameter was set to 0.5 mm. Ten random locations of each layer were measured, and the average of the measured values was calculated to obtain the thickness of the surface coating layer 6. The results are shown in Table 1.

[4] Evaluation of airtightness FIG. 7 is a schematic diagram showing the positional relationship between the lead frame material 1 and the resin when measuring the adhesion between the lead frame material of the present invention and the resin. As shown in FIG. 7, a total leakage test was performed on the lead frame material 1 obtained by the present invention and the comparative example, and the structure formed by die-casting with the resin 7 in a manner covering the lead frame material 1. Here, the total leakage test is to immerse the above structure in a high boiling point solvent, Fluorinert FC-40 (registered trademark), heated to 120℃±10℃ for 30 seconds or 120 seconds, and determine whether there is air leakage from the lead frame material 1 by whether bubbles are generated during immersion. The airtightness of the lead frame material 1 is evaluated based on the determination result.

Here, the evaluation result of the airtightness obtained by the total leakage test on the structure formed by the lead frame material 1 by the resin is set as the airtightness of the initial structure. Then, the heat cycle test is performed on the structure formed by the lead frame material 1 by the resin 7. The heat cycle test is repeated 50 times. The cycle is kept at a temperature of -50°C for 30 minutes and then kept at a temperature of 105°C for 30 minutes. The evaluation result of the airtightness obtained by the total leakage test on the structure after the heat cycle test is set as the airtightness of the structure after the heat cycle test.

The airtightness of the initial structure and the airtightness of the structure after the thermal cycle test were evaluated as follows: if no bubbles were generated within 120 seconds from the start of immersion in the high boiling point solvent, the airtightness was considered to be particularly excellent and evaluated as "A", if no bubbles were generated within 30 seconds from the start of immersion in the high boiling point solvent but bubbles were generated within 120 seconds from the start of immersion, the airtightness was considered to be excellent and evaluated as "B", and if bubbles were generated within 30 seconds from the start of immersion in the high boiling point solvent, the airtightness was considered to be low and undesirable and evaluated as "C". The results are shown in Table 2.

[5] Measurement and evaluation of the amount of powder falling The lead frame material 1 obtained from the present invention example and the comparative example was cut into pieces with a width of 60 mm and subjected to the tape peeling test specified in Japanese Industrial Standard JIS H 8504. The amount of weight reduction before and after the test was measured and evaluated as the amount of powder falling. For the measured amount of powder falling, a value of less than 3 mg/ ^dm2 was considered to be particularly excellent in that powder falling was not likely to occur and was evaluated as "A". In addition, a value of powder falling within the range of 3 mg/ ^dm2 or more and less than 12 mg/ ^dm2 was considered to be excellent in that powder falling was not likely to occur and was evaluated as "B". On the other hand, the range of the shedding amount of 12 mg/dm ² or more was considered undesirable because it was likely to cause powder falling and was evaluated as "C". The results are shown in Table 2.

[6] Comprehensive evaluation Among the evaluation results, for the three evaluation results of the initial structural airtightness, the structural airtightness after the thermal cycle test, and the amount of powder falling, if all three were evaluated as "A", it was considered to be particularly excellent in that the airtightness was high and powder falling was not likely to occur at any time before and after the thermal cycle test, and was evaluated as "A". In addition, for the three evaluation results, if all three were evaluated as "A" or "B" (but excluding the case where all three were evaluated as "A"), it was considered to be excellent in that the airtightness was high and powder falling was not likely to occur at any time before and after the thermal cycle test, and was evaluated as "B". On the other hand, for the three evaluation results, if at least one of the evaluation results is evaluated as "C", it is considered that the airtightness of at least one of the before and after heat cycle tests is unqualified or it is easy to cause powder falling and is evaluated as "C". The results are shown in Table 2.

[7] Evaluation of heat cycle resistance Furthermore, with respect to the evaluation results of the airtightness of the initial structure and the airtightness of the structure after the heat cycle test, the case where the initial airtightness is evaluated as "A" or "B" and the airtightness after the heat cycle test is evaluated as "A", and the case where the initial airtightness is evaluated as "B" and the airtightness after the heat cycle test is evaluated as "B", the structure is regarded as being particularly excellent in heat cycle resistance and is evaluated as "A". In addition, the case where the initial airtightness is evaluated as "A" and the airtightness after the heat cycle test is evaluated as "B", the structure is regarded as being excellent in heat cycle resistance and is evaluated as "B". On the other hand, when at least one of the evaluation results of the initial airtightness and the airtightness after the heat cycle test is evaluated as "C", the heat cycle resistance is considered to be low and is evaluated as "C". The results are shown in Table 2.

[Table 1]

[Table 2]

Based on the results of Table 1 and Table 2, the lead frame materials 1 of Examples 1 to 19 of the present invention have both the surface coating 3 and the side coating 4 with roughened upper surfaces, and the ratio of the average roughness height _h2 of the side coating 4 to the average roughness height _h1 of the surface coating 3 is within the appropriate range of the present invention. At this time, the lead frame materials 1 of Examples 1 to 19 of the present invention were evaluated as " _{A "} or "B" in the three evaluation results of the airtightness of the initial structure, the airtightness of the structure after the heat cycle test, and the amount of powder falling, and were also evaluated as "A" or "B" in the comprehensive evaluation.

FIG8 shows a secondary electron image of a cross section of the lead frame material of Example 1 of the present invention observed by SEM. It can also be seen from the secondary electron image of FIG8 that the lead frame material of Example 1 of the present invention has a roughened upper surface in both the surface coating 3 and the side coating 4, and that the average roughness height of the side coating 4 formed on the side surface 23 of the substrate 2 is significantly greater than the average roughness height of the surface coating 3 formed on the surface 21 of the substrate 2.

Therefore, the lead frame materials 1 of Examples 1 to 19 of the present invention are all rated "A" or "B" in the comprehensive evaluation, and therefore, at least under the condition of thermal cycle, which is a preset extreme use environment, they can still improve the airtightness of the package and are less likely to cause powder falling.

In particular, the lead frame materials 1 of Examples 1 to 5, 7, and 12 to 19 of the present invention have a first porosity _V1 and a second porosity _V2 both in the range of 32% or more and 64% or less, and a ratio _V2 / _V1 of the second porosity V2 to the first porosity _V1 in the range of 0.50 or more and _0.91 or less. In this case, they are rated "A" in the evaluation of the heat cycle resistance of the structure, and are particularly excellent in that the airtightness is less likely to be reduced due to the heat cycle test.

On the other hand, the lead frame materials of Comparative Examples 1 and 2 do not have any of the surface coating 3 and the side coating 4. In addition, the ratio h ₂ /h ₁ of the average roughness height h ₂ of the side coating 4 to the average roughness height h ₁ of the surface coating 3 of Comparative Examples 3 to 7 is outside the appropriate range of the present invention. Therefore, the lead frame materials of Comparative Examples 1 to 7 have at least one of the three evaluation results of "C" in the initial structure airtightness, the structure airtightness after the heat cycle test, and the amount of powder falling, and are also evaluated as "C" in the comprehensive evaluation.

1,1A: lead frame material 2: substrate (or base material) 21: substrate surface 22: substrate back 23: substrate side 3,3A: surface coating 30: upper surface of surface coating 4: side coating 40: upper surface of side coating 5: roughening layer 50: upper surface of roughening layer 6: surface coating layer 7: resin _h1 : average roughness height of surface coating _h2 : Average roughness height of the side coating A1: Highest point of the upper surface of the surface coating B1: Lowest point of the upper surface of the surface coating P1: Area of the surface coating present in the evaluation area S1: Area of the surface coating not present in the evaluation area A2: Highest point of the upper surface of the side coating B2: Lowest point of the upper surface of the side coating P2: Area of the side coating present in the evaluation area S1: Area of the side coating not present in the evaluation area L1, L2: Length of the entire line (width of 10 concavities) l ₁ , l ₂ , n ₁ , n _2, m ₂ : Imaginary lines M1, M2: Evaluation area T: Thickness

FIG. 1 is a schematic cross-sectional view of a portion of a lead frame material according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a surface coating formed on a surface of a substrate in a lead frame material having the same structure as FIG. 1, and is a view for explaining the relationship between the upper surface of the surface coating and imaginary lines l ₁ and n _1, and the relationship between the imaginary line m ₁ and the average roughness height h ₁ of the surface coating. FIG. 3 is a cross-sectional view showing an evaluation region M1 in a surface coating having the same structure as FIG. 2, and is a view for explaining the relationship between the imaginary lines l ₁ and n ₁ and the evaluation region M1, and the relationship between the evaluation region M1 and a region P1 where the surface coating exists and a region S1 where the surface coating does not exist. FIG. 4 is a cross-sectional view showing a side coating formed on the side surface of a substrate in a lead frame material having the same structure as FIG. 1, and is a view for explaining the relationship between the upper surface of the surface coating and the imaginary lines l ₂ and n _2, and the relationship between the imaginary line m ₂ and the average roughness height h ₂ of the surface coating. FIG. 5 is a cross-sectional view showing an evaluation area M2 in a side coating formed on the side surface of a substrate and having the same structure as FIG. 4, and is a view for explaining the relationship between the imaginary lines l ₂ and n ₂ and the evaluation area M2, and the relationship between the evaluation area M2 and the surface coating presence area P2 and the surface coating absence area S2. FIG. 6 is a cross-sectional view showing an outline of a lead frame material according to another embodiment of the present invention. Fig. 7 is a schematic diagram showing the positional relationship between the lead frame material and the resin when the adhesion between the lead frame material and the resin is measured. Fig. 8 is a secondary electron image of the cross section of the lead frame material of Example 1 of the present invention observed by SEM (scanning electron microscope).

Domestic storage information (please note in the order of storage institution, date, and number) None Foreign storage information (please note in the order of storage country, institution, date, and number) None

1: Lead frame material

2: Matrix (or base material)

21: Surface of substrate

22: The back of the substrate

23: Side of the substrate

3: Surface coating

30: Upper surface of the surface coating

4: Side coating

40: Upper surface of the side coating

5: Roughening layer

T:Thickness

Claims (13)

A lead frame material comprises: a conductive substrate; a surface coating formed on one or both of the surface and the back surface of at least a portion of the substrate; and a side coating adjacent to the surface coating and formed on the side surface of at least a portion of the substrate; in the lead frame material, the surface coating and the side coating both have a roughened upper surface, and when the average roughness height of the surface coating is set to _h1 and the average roughness height of the side coating is set to _h2 , the ratio of the average roughness height _h2 of the side coating to the average roughness height _h1 of the surface coating, _h2 /h1 _, is greater than 1.35. The lead frame material as claimed in claim 1, wherein the average roughness height _h1 of the surface coating is in the range of 0.5 μm to 3.5 μm, and the average roughness height _h2 of the side coating is in the range of 1.0 μm to 6.5 μm. The lead frame material as described in claim 1, wherein, in a cross-section of the surface coating, a first porosity in a first measured area divided by an imaginary line l ₁ and an imaginary line n ₁ is set to V ₁ , the imaginary line l ₁ being drawn through the highest point of the upper surface of the surface coating and parallel to the surface of the substrate, and the imaginary line n ₁ being drawn through the lowest point of the upper surface of the surface coating and parallel to the surface of the substrate; and in a cross-section of the side coating, a second porosity in a second measured area divided by an imaginary line l ₂ and an imaginary line n ₂ is set to V ₂ , the imaginary line l ₂ being drawn through the highest point of the upper surface of the side coating and parallel to the side of the substrate, and the imaginary line n 1 being drawn through the lowest point of the upper surface of the side coating and parallel to the side of the substrate. ₂ is drawn in a direction passing through the lowest point of the upper surface of the side coating and parallel to the side surface of the substrate. In this case, the ratio V ₂ /V ₁ of the second porosity V ₂ to the first porosity V ₁ is in the range of 0.50 or more and 0.91 or less. The lead frame material as described in claim 3, wherein the first porosity _V1 and the second porosity _V2 are both in the range of greater than 32% and less than 64%. The lead frame material as described in claim 1, wherein the substrate is composed of copper, copper alloy, iron, iron alloy, aluminum or aluminum alloy. The lead frame material as claimed in claim 1, wherein, when the thickness of the substrate is set to T, the ratio of the thickness T of the substrate to the average roughness height _h2 of the side coating (T/ _h2 ratio) is in the range of 15.0 to 200.0. The lead frame material as described in claim 1, wherein the surface coating and the side coating both have a roughening layer. The lead frame material as described in claim 7, wherein the roughened layer is composed of copper, copper alloy, nickel or nickel alloy. The lead frame material as described in claim 7, wherein the roughened layer is an electroplated coating. The lead frame material as described in claim 7, wherein the surface coating and the side coating further have at least one surface coating layer formed on the upper surface of the roughened layer. A lead frame material as described in claim 10, wherein the surface coating layer is composed of a metal or alloy having a composition different from that of the roughening layer, and the metal or alloy is: copper, copper alloy, nickel, nickel alloy, cobalt, cobalt alloy, palladium, palladium alloy, rhodium, rhodium alloy, ruthenium, ruthenium alloy, platinum, platinum alloy, iridium, iridium alloy, gold, gold alloy, silver, silver alloy, tin, tin alloy, indium or indium alloy. A method for manufacturing a lead frame material, which is the method for manufacturing a lead frame material as described in any one of claims 1 to 11, and includes a coating forming step, wherein the aforementioned surface coating having a roughened upper surface and the aforementioned side coating are formed on the aforementioned substrate by electroplating. A semiconductor package comprises a lead frame formed using the lead frame material described in any one of claims 1 to 11.