JP2001230345A - Semiconductor device, its manufacturing method and lead frame for use in manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device which has a high long-time reliability and can attain a high density structure at a low cost, a lead frame used for manufacturing the device and a method of manufacturing a semiconductor device suited for miniaturization. SOLUTION: The semiconductor device is composed of a semiconductor element 1, outer electrodes 3 connected by wire bonding 2 to electrodes of the semiconductor element 1, and an electrically insulative resin 4 sealing them in one body. The outer electrodes 3 and a recessed die pad 6 for the semiconductor element 1 are constituted so that their tops project at least 0.003 mm into the sealing resin 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor device, a lead frame used for assembling the same, and a method of manufacturing a semiconductor device suitable for miniaturization.

[0002]

2. Description of the Related Art In recent years, as represented by mobile phones, etc.,
Electronic devices are being reduced in size and cost. For this reason, the density and weight of the semiconductor device used for such electronic equipment have been increased, and the density of the semiconductor device mounted on a circuit board has been increased. In addition, since it is also desired to improve the reliability of this kind of electronic equipment, it is required to increase the density and reliability of the semiconductor device. Furthermore, on the other hand, reduction in the manufacturing cost of the semiconductor device is also desired. Therefore, a semiconductor device that satisfies all of these requirements is now required.

By the way, conventionally, from the viewpoint of increasing the density of a semiconductor device, a flip-chip type mounting technique is known. This is because the semiconductor element is directly mounted on the mounting substrate without being exposed, so that it is possible to improve the electrical characteristics together with the high density, but since the semiconductor element is not sealed with resin, heat resistance, mechanical strength and There is a problem in terms of moisture resistance. On the other hand, a semiconductor device that is generally widely used is formed by sealing a semiconductor element with a resin, and has no problem in terms of heat resistance, mechanical strength, and moisture resistance. There is a disadvantage that high density cannot be achieved due to the necessity of widening.

In recent years, a ball grit array (BGA) and a chip size package (CSP), which have a lower mounting density than flip-chip devices but can be handled in the same manner as existing semiconductor devices, have been developed. However, in these semiconductor devices, it is necessary to connect a semiconductor element and an external terminal via an insulating layer such as a sealing resin or a printed wiring board. For this reason, an opening must be provided in the insulating layer, and a conductor layer must be formed in the opening to serve as a conduction path. However, the step of providing this opening is a major bottleneck in the manufacturing process of the semiconductor device, and the manufacturing cost is reduced. As a result. Further, since the circuit board is incorporated into the semiconductor device, there is also a problem that the weight cannot be reduced.

[0005] In order to solve such problems,
Conventionally, a semiconductor device having a structure as shown in FIGS. 11 and 12 has been proposed. This semiconductor device has a semiconductor element 1
And an external electrode 3 connected to the electrode of the semiconductor element 1 by a wire bond 2 and a resin 4 for integrally sealing the external electrode 3. To obtain this semiconductor device, FIG. A lead frame as shown in FIGS. 14A and 14B is used, and it is manufactured by a procedure as shown in FIGS. 14A and 14B. That is, the semiconductor device shown in FIG.
A resist layer is provided on the surface of a lead frame material made of an iron alloy, copper, a copper alloy, or the like, exposed and developed using a predetermined mask, and the resist layer at a position corresponding to the external electrode 3 is removed. The material is half-etched to form a concave portion 5a on which the external electrode 3 is to be formed, and
By providing a plating layer on the inner surface of the concave portion 5a using at least one metal selected from the group consisting of gold, silver, copper, palladium, titanium and nickel, FIG.
After obtaining the lead frame 5 as shown in FIG.
As shown in FIG. 14, the semiconductor element 1 is mounted on the die pad portion of the lead frame 5, and the electrodes of the semiconductor element 1 and the external electrodes 3 are connected by wire bonding 2 as shown in FIG. These are obtained by sealing these with resin 4 and finally dissolving and removing the lead frame 5 as shown in FIG. The semiconductor device shown in FIG. 12 also has a lead frame 5 (FIG. 13B) having a concave portion 5a for forming the external electrode 3 and a concave portion 5b for accommodating the semiconductor element 1 obtained as described above. ) Is manufactured through the same steps as described above as shown in FIGS. 14 (a), (b) and (c).

[0006]

As described above, it has been possible to provide a semiconductor device capable of increasing the mounting density on a circuit board and reducing its weight while maintaining low cost. When the device was mounted on a circuit board and used for actual use, it was found that there was a problem in terms of long-term reliability. Specifically, it has been pointed out that the external electrodes are easily damaged.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the prior art, and has as its object to provide a semiconductor device which has high long-term reliability, can achieve high density at low cost. And a lead frame used for manufacturing the same, and a method for manufacturing a semiconductor device suitable for miniaturization.

[0008]

In order to achieve the above object, a semiconductor device according to the present invention comprises a semiconductor element, an external electrode connected to an electrode of the semiconductor element, and an integrated semiconductor element and external electrode. A semiconductor device mainly composed of an electrically insulating resin to be sealed, wherein an upper portion of the external electrode is configured to project at least 0.003 mm into the sealing resin.

A semiconductor device according to the present invention includes a semiconductor element, an external electrode connected to an electrode of the semiconductor element,
In a semiconductor device mainly including a concave die pad for holding the semiconductor element and an electrically insulating resin for integrally sealing the concave die pad, an upper portion of the external electrode and an upper portion of the concave die pad are both sealed. It is characterized in that it is configured to project at least 0.003 mm into the resin.

According to the present invention, a flange is formed on an upper end of the external electrode and an outer periphery of an upper end of the concave die pad.

Further, according to the present invention, the external electrode has a concave shape and is formed such that a top diameter is larger than a bottom diameter.

According to the present invention, the external electrode and the concave die pad are made of at least one kind of metal among gold, silver, copper, palladium, titanium and nickel.

Further, according to the present invention, the protrusion length of the upper part of the external electrode into the sealing resin and the protrusion length of the upper part of the concave die pad into the sealing resin are 0.1 mm.
It is characterized as follows.

In order to achieve the above object, a lead frame according to the present invention has a number of concave external electrodes at least equal to the number of electrodes of a semiconductor element used, and is formed using a material different from the external electrodes. The upper part of the external electrode is projected at least 0.003 mm from the surface of the lead frame.

Further, a lead frame according to the present invention comprises a concave die pad capable of accommodating a semiconductor element to be used;
It has a number of concave external electrodes at least as many as the number of electrodes of the semiconductor element, and the concave die pad and the concave external electrode are formed using different materials, and an upper part of the concave die pad. The upper part of the concave external electrode is at least 0.003 from the surface of the lead frame.
It is characterized by being protruded by mm.

According to the present invention, the lead frame is made of any one of iron alloy, copper and copper alloy, and the concave die pad and the external electrode are made of a group consisting of gold, silver, copper, palladium, titanium or nickel. It is characterized by being composed of at least one selected metal.

In a method of manufacturing a semiconductor device according to the present invention, after a semiconductor element is mounted on a die pad of a lead frame and joined, an electrode of the semiconductor element and an external electrode of the lead frame are connected by wire bonding. Next, the semiconductor element, the wire bonding, and the external electrode are resin-sealed so that a part of the external electrode is exposed after the lead frame is dissolved and removed, and then the lead frame is dissolved and removed. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on illustrated embodiments. In each embodiment, substantially the same members and portions as those described in the related art are denoted by the same reference numerals, and detailed description is omitted. FIG. 1 is a sectional view showing a configuration of an embodiment of a semiconductor device according to the present invention. The semiconductor device according to the present embodiment includes a semiconductor element 1 having a concave die pad 6 bonded to the back surface thereof with an insulating adhesive 7, an external electrode 3 connected to an electrode of the semiconductor element 1 by wire bonding 2, and a sealing element. And a concave die pad 6
And the upper part of the external electrode 3
It is configured to protrude by 3 mm. As described above, according to the present embodiment, since the upper portion of the external electrode 3 and the upper portion of the concave die pad 6 are securely sealed and fixed by the resin 4, the heat resistance, mechanical strength, and moisture resistance of the semiconductor device are reduced. Not only good, but also long-term stability can be improved. In addition, miniaturization can be achieved without increasing the thickness of the entire semiconductor device, and since the external electrodes 3 are exposed, the semiconductor device can be easily joined to a mounting substrate. In addition, as a result of measuring the cup shear strength using the semiconductor device according to the present embodiment and evaluating the terminal bonding strength, the cup shear strength was at least twice that of the conventional product.

FIG. 2 is a sectional view showing the structure of another embodiment of the semiconductor device according to the present invention. In the semiconductor device of this embodiment, the semiconductor element 1 is completely buried in the sealing resin 4 without using the concave die pad, and the upper portion of the external electrode 3 projects 0.1 mm into the sealing resin 4. This embodiment is different from the embodiment shown in FIG. The semiconductor device according to this embodiment also has the same operation and effect as the embodiment of FIG. 1. However, as a result of measuring the cup shear strength using this semiconductor device and evaluating the terminal joining strength, the cup shear strength is 2 times that of the conventional product. 0.5 times.

FIG. 3 is a sectional view showing the structure of still another embodiment of the semiconductor device according to the present invention. The semiconductor device of the present embodiment is different from that of FIG. 1 in that the upper portion of the external electrode 3 protrudes 0.1 mm into the encapsulating resin 4 and a flange 3a having a width of 0.4 mm is formed outside the upper end of the external electrode 3. Different from the example. This embodiment also has the same function and effect as the embodiment of FIG. 1, but as a result of measuring the cup shear strength and evaluating the terminal joining strength, the cup shear strength was three times that of the conventional product. Note that such a flange 3a can also be formed outside the upper end of the concave die pad 6, so that the semiconductor element 1 can be held more stably.

FIG. 4 is a sectional view showing the structure of still another embodiment of the semiconductor device according to the present invention. The semiconductor device according to the present embodiment is characterized in that the upper portion of the external electrode 3 protrudes 0.003 mm into the encapsulating resin and the side surface thereof is formed to open toward the upper end at an inclination angle of 10 ° with respect to the vertical surface. It differs from the embodiment of FIG. That is, according to this embodiment, the external electrode 3 is formed such that the top diameter is larger than the bottom diameter. This embodiment also has basically the same operation and effect as the embodiment of FIG. 1, but the cup shear strength is 1.4 times that of the conventional product as a result of measuring the cup shear strength and evaluating the terminal joining strength. Was.

FIG. 5 is a sectional view showing the structure of a main part of still another embodiment of the semiconductor device according to the present invention. This example is
An earth bonding contact portion 6a is formed on a part of the concave die pad 6 so that stable bonding can be performed, and the instability of bonding as in the conventional structure is eliminated.

FIG. 6 is a sectional view showing the structure of still another embodiment of the semiconductor device according to the present invention. In this embodiment, an opening 4a is formed in the sealing resin 4 so that a part of the external electrode 3 is exposed, and the solder ball 7 is inserted into the opening 4a so that the external electrode 3 and the solder ball 8 are joined. It is characterized in that it is configured as As a result, a BGA type semiconductor device having the same functions and effects as the embodiment of FIG. 1 can be provided.

FIG. 7 is a sectional view showing an embodiment of the lead frame according to the present invention, which is used for manufacturing the semiconductor device shown in FIG. A predetermined number of concave external electrodes 3 and a die pad 6 are formed on the lead frame 5, and the upper portions of the external electrodes 3 and the die pad 6 project from the surface of the lead frame 5 by 0.003 mm. If the protruding height is less than 0.003 mm, sufficient strength cannot be obtained when resin sealing is performed. If the protruding height is too high, the thickness of the semiconductor device becomes too thick, and the demand for miniaturization cannot be satisfied. Such a concave external electrode 3 and die pad 6 can be easily formed by using a well-known photolithographic method.

Next, referring to FIG.
Will be described. In this figure, for convenience of explanation, the lead frames 5 are schematically shown as a thin plate on the upper side, and as a pair in a cross-sectional view with an exaggerated thickness on the lower side. First, the lead frame 5 shown in FIG.
A resist 9 is applied on the thin plate as shown in FIG. 8B. In this embodiment, a dry film having a thickness of 0.025 mm is laminated as a resist 9 on a copper material having a thickness of 0.125 mm. Next, after the pattern is baked on the resist 9 using a mask on which a pattern for forming the external electrode 3 and the concave die pad 6 is drawn, the resist 9 is developed with an aqueous solution of sodium carbonate to form a resist pattern 9 ′ for etching. (See FIG. 8C). Next, an aqueous solution of ferric chloride at 55 ° C. is sprayed from above the resist pattern 9 ′ to form a concave external electrode 3 and a concave portion 5 a (5 b) serving as a concave die pad 6 (FIG. 8D).
reference). Next, plating was performed on the inner surface of the concave portion 5a (5b) to form the concave electrode 3 and the concave die pad 6 (see FIG. 8E). As plating material (electrode material),
Palladium (Pd) / nickel (Ni) palladium (P
d) was used. Further, the resist 9 is peeled off with caustic soda, the resist is again laminated on the back surface, the surface of the lead frame 5 is half-etched, and then the resist is peeled off with caustic soda to remove the lead frame 5 as shown in FIG. (See FIG. 8 (f)). In this case, the half-etching time determines the height of each upper protrusion of the external electrode 3 and the die pad 6.

In this embodiment, a copper material is used as the lead frame 5. However, the present invention is not limited to this, and a material generally used with a resist material, that is, an iron alloy, a copper alloy, or the like may be used. The electrode material may be any material as long as it is not corroded by the solution of the lead frame 5 used in the manufacturing process of the semiconductor device described later and ensures the wire bonding property and the solder wettability. , Gold, silver, palladium, titanium or nickel is used. In the present embodiment, the external electrodes 3 are formed by a plating method, but other methods may be used as long as a similar configuration is adopted.

FIG. 9 is a sectional view showing another embodiment of the lead frame according to the present invention, which is used to manufacture the semiconductor device shown in FIG. Lead frame 5 of this embodiment
Is manufactured using a mask on which a pattern for forming only the external electrode 3 is drawn and through the same processing steps as described above. The external electrode 3 is used to determine the position when the semiconductor element 1 is mounted. It has become useful. The upper part of the external electrode 3 is placed on the surface of the lead frame 5 by 0.01
mm protruding.

Next, a method of manufacturing the lead frame 5 used for manufacturing the semiconductor device shown in FIG. 3 will be described with reference to FIG. First, after obtaining the lead frame 5 on which the external electrode 3 and the die pad 6 are formed through the steps shown in FIG. 8, the pattern of the external electrode 3 and the die pad 6 and the mask used first for the external electrode 3 are again obtained. By performing plating similarly using a plating mask (not shown) having an opening having a larger diameter, a concave external electrode 3 having a flange 3a as shown in FIG. 3 is obtained. After that, the resist is peeled off with caustic soda, and then a resist is provided on the surface of the lead frame 5.
The upper surface of the flanged external electrode 3 and the die pad 6 is projected by a predetermined amount by half-etching the surface. In this embodiment,
The diameter of the opening was 0.8 mm. In order to make the cross-sectional shape of the external electrode 3 a side surface inclined as shown in FIG. 4, the etching conditions at the time of etching shown in FIG. 8D may be appropriately selected. The choice can be made easily.

FIG. 10 is a sectional view showing one embodiment of a method of manufacturing a semiconductor device according to the present invention, showing a procedure for manufacturing the semiconductor device shown in FIG. 1 using the lead frame 5 shown in FIG. I have. First, as shown in FIG. 10A, a semiconductor element 1 having a thermosetting polyimide resin adhesive film applied as an electrically insulating adhesive 7 on the back surface is joined to a concave die pad 6 of a lead frame 5, Next, the external electrodes 3 of the lead frame 5 and the electrodes of the semiconductor element 1 are connected by wire bonding 2. Next, these are integrally sealed with the sealing resin 4 (see FIG. 10B). Thereafter, the semiconductor device sealed with the resin together with the lead frame 5 is immersed in an aqueous solution of sodium persulfate to dissolve and remove the lead frame 5, thereby completing the semiconductor device (FIG. 10).
(C)). Thus, the semiconductor device according to the present invention can be mass-produced easily and inexpensively.

If a semiconductor device is manufactured using the lead frame 5 shown in FIG. 9 by the same procedure as in the above embodiment, a semiconductor device having the structure shown in FIG. 2 can be obtained.

[0031]

As described above, according to the present invention, it is possible to provide a semiconductor device having high long-term reliability and capable of achieving high density at low cost, and a lead frame for manufacturing the same. Further, a semiconductor device suitable for miniaturization can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of a semiconductor device according to the present invention.

FIG. 2 is a sectional view showing the configuration of another embodiment of the semiconductor device according to the present invention.

FIG. 3 is a cross-sectional view showing a configuration of still another embodiment of the semiconductor device according to the present invention.

FIG. 4 is a cross-sectional view showing a configuration of still another embodiment of the semiconductor device according to the present invention.

FIG. 5 is a cross-sectional view showing a configuration of still another embodiment of the semiconductor device according to the present invention.

FIG. 6 is a sectional view showing a configuration of still another embodiment of the semiconductor device according to the present invention.

FIG. 7 is a sectional view showing a configuration of an embodiment of a lead frame according to the present invention.

FIG. 8 is a process diagram for describing a manufacturing procedure of the lead frame according to the present invention.

FIG. 9 is a cross-sectional view showing the configuration of another embodiment of the lead frame according to the present invention.

FIG. 10 is a process chart for explaining the procedure for manufacturing the semiconductor device according to the present invention.

FIG. 11 is a cross-sectional view illustrating a configuration of an example of a conventional semiconductor device.

FIG. 12 is a cross-sectional view showing the configuration of another example of a conventional semiconductor device.

FIG. 13 is a cross-sectional view showing the structure of two different lead frames used to manufacture a conventional semiconductor device.

FIG. 14 is a process chart illustrating a manufacturing procedure of the semiconductor device shown in FIG. 11;

FIG. 15 is a process chart illustrating a manufacturing procedure of the semiconductor device shown in FIG. 12;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor element 2 Wire bonding 3 External electrode 4 Sealing resin 5 Lead frame 6 Concave die pad 7 Insulating adhesive 8 Solder ball 9 Resist 9 'Resist pattern

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4M109 AA01 BA01 CA21 DA04 DA10 DB02 FA04 5F067 AA01 AA03 AA09 AB04 BB04 BB05 BC12 BE02 CA03 DA16 DC13 DC17 DE08 DE10 DF02 EA01 EA04 EA05

Claims (15)

[Claims] 1. A semiconductor device mainly comprising a semiconductor element, an external electrode connected to an electrode of the semiconductor element, and an electrically insulating resin integrally sealing the semiconductor element and the external electrode. A semiconductor device, wherein an upper portion of an external electrode is configured to project at least 0.003 mm into the sealing resin. 2. A semiconductor device comprising: a semiconductor element; an external electrode connected to an electrode of the semiconductor element; a concave die pad for holding the semiconductor element; and an electrically insulating resin for integrally sealing these. Wherein the upper portion of the external electrode and the upper portion of the concave die pad both project at least 0.003 mm into the sealing resin. 3. The semiconductor device according to claim 1, wherein a flange is formed at an upper end of the external electrode. 4. The semiconductor device according to claim 2, wherein a flange is formed on an outer periphery of an upper end of the concave die pad. 5. The semiconductor device according to claim 1, wherein the external electrode has a concave shape, and a top diameter is larger than a bottom diameter. 6. The external electrode or the external electrode and the concave die pad are made of at least one kind of metal among gold, silver, copper, palladium, titanium and nickel. The semiconductor device according to any one of the above. 7. The semiconductor device according to claim 1, wherein a protruding length of an upper portion of said external electrode into said sealing resin is 0.1 mm or less. 8. The semiconductor device according to claim 2, wherein a protruding length of an upper portion of the concave die pad into the sealing resin is 0.1 mm or less. 9. The semiconductor device according to claim 1, further comprising a plurality of concave external electrodes having at least as many electrodes as the number of electrodes of the semiconductor element to be used, wherein said external electrodes are made of a material different from said external electrodes. At least 0.0
3. The projection according to claim 1, wherein the projection is 03 mm.
9. A lead frame used for manufacturing the semiconductor device according to any one of claims 8 to 8. 10. A concave die pad capable of accommodating a semiconductor element to be used, and a concave external electrode having a number at least equal to the number of electrodes of the semiconductor element, wherein the concave die pad, the concave external electrode, Is made of a different material, and the upper part of the concave die pad and the upper part of the concave external electrode are projected at least 0.003 mm from the surface of the lead frame. 9. A lead frame used for manufacturing the semiconductor device according to any one of 8. 11. The lead frame is made of any one of iron alloy, copper, and copper alloy, and the external electrode is made of at least one metal selected from the group consisting of gold, silver, palladium, titanium, and nickel. The lead frame according to claim 9, wherein: 12. The lead frame is made of any one of iron alloy, copper and copper alloy, and the concave die pad and the external electrode are at least one selected from the group consisting of gold, silver, copper, palladium, titanium and nickel. The lead frame according to claim 10, wherein the lead frame is made of a metal. 13. The lead frame according to claim 9, wherein a height of an upper portion of the external electrode protruding from a surface of the lead frame is 0.1 mm or less. 14. The height of the upper part of the concave die pad and the upper part of the external electrode protruding from the surface of the lead frame is 0.1 mm or less.
Or the lead frame according to 12. 15. A semiconductor device is mounted on a die pad of a lead frame and joined, and then the electrodes of the semiconductor device and the external electrodes of the lead frame are connected by wire bonding. And a method of manufacturing a semiconductor device, wherein the lead frame is dissolved and removed after resin sealing is performed so that a part of the external electrode is exposed after dissolving and removing the lead frame.