JPH07249734A - High power semiconductor device - Google Patents

Abstract

PURPOSE:To enhance the lifetime in TFT test by making a groove for fitting a board in the lower part of an enclosure on the inside of the side wall, fitting a board comprising a ceramic board having a recessed cross-section and a metal part formed on the main surface on the opposite side to the recessed side into the groove and providing a bottom cover for the enclosure thereby eliminating the need of a metal heat plate and a soldering material. CONSTITUTION:A ceramic board la having cross-section protruding downward is bonded selectively with a copper plate 1b on the flat surface on the opposite side and a power element 3 is bonded to a predetermined part on the surface of the copper plate 1b through a high melting point solder 2. A terminal holder 6 built in an outer electrode is then bonded to the copper plate 1b. The ceramic board la is fitted, at the peripheral end part, in a groove 8 made in the lower board of a resin enclosure 7 and then the ceramic board 1a is urged downward by means of a stop metal 9 fixed to the upper face part of the groove 8. Furthermore, the board 1 is bonded to the enclosure 7 through an adhesive 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high power semiconductor device having a power element for controlling high power.

[0002]

2. Description of the Related Art In a high power semiconductor device (hereinafter, simply referred to as a module) having a plurality of power elements for controlling a large power, a large amount of heat is generated in the power element portion during use and this heat is efficiently transferred to the outside. It is an important issue to improve the reliability of the module.

As a conventional module having an envelope structure satisfying these functions, the one shown in FIG. 11 is generally used.

Reference numeral 101 in FIG. 11 denotes a DBC substrate, and copper plates 103 selectively patterned are formed on both surfaces of a ceramic plate 102. This DBC substrate forms an alloy layer between the ceramic plate 102 and the copper plate 103 and uses it as an adhesive. A power element 105 is fixed on the surface of a predetermined portion of the patterned copper plate 103 via a high melting point solder 104.

Further, the electrodes are taken out from the upper surface of the power element 105 to the copper plate 103 on the DBC substrate 101 by the bonding wire 106. further,
Due to the low melting point solder 107, the copper plate 103 on the upper surface side of the DBC substrate 101 has a terminal holder 1 with a built-in external electrode terminal
08, and a metal radiator plate 109 is fixed to the copper plate 103 on the lower surface side.

[0006] These constituent elements are the resin case 1.
10 and the resin case 110 is fixed to the metal heat dissipation plate 109 with an adhesive agent 111. Further, the space inside the resin case 110 is filled with a silicone resin gel agent 112 as a lower layer filling material and an epoxy resin casting agent 113 as an upper layer filling material to seal the inside of the resin case 110.

[0007]

In the module having the above structure, the reliability life test (TFT test) of the module is performed.
In this case, there was a problem that the low melting point solder 107 fixing the DBC substrate 101 and the metal heat dissipation plate 109 was fatigued and cracked.

More specifically, in this TFT test, ON / OFF is repeated in a constant cycle, and the influence of the temperature rise due to the energization of the power element 105 at the time of ON and the cooling effect by the forced cooling at the time of OFF is evaluated. It is a test. When a temperature change is applied to two types of materials having different thermal expansion coefficients, the two types of materials repeatedly expand and contract in volume according to their own thermal expansion coefficients.

This phenomenon is basically the same even when the two kinds of materials are adhered via an intermediate such as solder. In this case, the difference in the coefficient of thermal expansion between the two kinds of materials is the intermediate adhesion. This results in the accumulation of stress (strain) on the object. This accumulated stress fatigues the material. In particular, solder materials are susceptible to fatigue due to thermal energy.

The low melting point solder 107, which is an adhesive intermediate between the conventional DBC substrate 101 and the metal heat dissipation plate 109, exists in the passage through which the heat generated in the power element 105 escapes to the outside of the module, and other solder (power). Since the bonding area is larger than that of the high melting point 104 for fixing the element or the low melting point solder 107) for fixing the terminal holder, it is the most fatigued portion in the TFT test.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a high power semiconductor device having a significantly improved life in a TFT test. Another object is to provide a high-quality, high-power semiconductor device having excellent durability.

[0012]

In order to achieve the above object, the first aspect of the present invention is characterized in that a ceramic plate having a reverse convex cross section and a metal formed on the main surface opposite to the convex side of the ceramic plate. And a power element mounted on the surface of the metal member of the substrate.

In order to achieve the above object, a second aspect of the present invention is that a substrate on which a power element is mounted, a terminal holder electrically connected to the power element, the power element and the terminal holder are provided. And a casing for casing,
In a high-power semiconductor device in which a space formed by the envelope and the substrate inside the envelope is filled with resin so as to lead the terminal holder to the outside, a lower part inside a sidewall of the envelope is provided. A substrate mounting groove is provided in the substrate, and the substrate is configured to be mounted in the substrate mounting groove to serve as a bottom lid of the envelope.

Further, in the second invention, preferably, the substrate has a reverse convex shape in section by cutting out a lower side of a peripheral end portion thereof, and the peripheral end portion of the substrate is mounted in the substrate mounting groove. To do so.

[0015] Preferably, in the second aspect of the invention, a holding metal fitting for pressing the substrate is provided in the substrate mounting groove.

Preferably, in the second invention, the substrate is composed of a ceramic member having a reverse convex cross section and a metal member formed on a main surface opposite to the convex surface side of the ceramic member, The power element is mounted on the surface of the metal member.

Preferably, in the second invention, a metal guide is embedded in a side wall of the envelope so as to be located at a lower side of the substrate mounting groove.

Preferably, in the second aspect of the present invention, a screw hole for fixing an external housing is formed in an outer peripheral portion of the envelope extending from the outer wall surface of the envelope in a direction opposite to the substrate. To do.

In order to achieve the above object, the third aspect of the present invention is that a substrate on which a power element is mounted, a terminal holder electrically connected to the power element, the power element and the terminal holder are provided. And a casing for casing,
In a high-power semiconductor device in which a resin is filled in a space inside the envelope formed by the envelope and the substrate so as to lead the terminal holder to the outside, the substrate is the envelope. It is formed integrally with the envelope so as to form a bottom lid.

In order to achieve the above-mentioned object, a fourth aspect of the invention is characterized in that a substrate on which a power element is mounted, a terminal holder electrically connected to the power element, and the power element and the terminal holder are casings. In a high-power semiconductor device in which a resin is filled so as to lead the terminal holder to the outside in a space inside the envelope formed by the envelope and the substrate, The substrate is configured to be larger than the envelope by mounting the envelope on the upper surface side thereof, and a screw for fixing an external casing to an outer extending portion extending from the envelope to the outside. The holes have been drilled.

[0021]

According to the above-mentioned structure, according to the present invention, when the envelope is used, the substrate is fixed by the envelope.
It is possible to omit the metal heat dissipation plate that has been conventionally used for fixing the board and the solder material that fixes the board to the board.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the structure of a high power semiconductor device according to the first embodiment of the present invention.

This module has a high thermal conductivity substrate 1 composed of a ceramic plate 1a having a reverse convex cross section and a copper plate 1b. A copper plate 1b is selectively arranged and fixed on the main surface side of the ceramic plate 1a, that is, on the flat surface opposite to the convex surface side of the ceramic plate 1a. A power element 3 is formed on the surface of a predetermined portion of the copper plate 1b via a high melting point solder 2.
Is stuck.

Further, the electrode is taken out from the upper surface of the power element 3 to the surface of the copper plate 1b by the bonding wire 4. Further, a terminal holder 6 with a built-in external electrode terminal is fixedly erected on the copper plate 1b via the low melting point solder 5.

The peripheral edge of the ceramic plate 1a is mounted in a board mounting groove 8 provided in the lower portion of a resin case (envelope) 7 made of a resin material, and in addition, the mounted ceramic plate 1a.
Is pressed downward by a retainer fitting 9 attached to the upper surface of the board mounting groove 8. The substrate 1 and the resin case 7 are fixed to each other with an adhesive 10.

Further, the space inside the resin case formed by the resin case 7 and the substrate 1 is filled with the silicone resin gel agent 11 as the lower layer filler and the epoxy resin casting agent 12 as the upper layer filler, As a result, the inside of the resin case 7 is sealed. The silicone resin gel agent 11 and the epoxy resin casting agent 12 are both curable resins.

Further, a screw hole 13 for fixing an external heat radiation plate or the like is formed in an outer extending portion extending from the outer wall surface of the resin case 7 in the direction opposite to the substrate 1. Here, the external heat radiation plate is a heat radiation plate externally attached to the module and having a large heat capacity.

Next, each component of FIG. 1 will be specifically described. FIG. 2 shows a cross-sectional view of the high thermal conductivity substrate 1 of FIG. 1, and as described above, the ceramic plate 1 having a reverse convex cross section.
It is composed of a and a copper plate 1b selectively fixed to the surface thereof.

FIG. 3 is a perspective view showing the shape of the resin case 7 of FIG. 1, which is in the form of a rectangular box, and the resin case 7 shown has the front side lid (side lid in the board insertion direction) removed. Shows the closed state. As shown in the figure, the resin case 7
A board mounting groove 8 for inserting the board 1 along the side wall is provided at a lower portion inside the side wall of the board, and a holding metal fitting 9 is mounted along the upper surface of the board mounting groove 8. In addition, screw holes 13 for fixing the external housing are formed in two outer extending portions of the left and right side walls of the resin case 7, respectively.

FIG. 4A shows a cross section taken along the line XX 'in FIG. 3 with the substrate 1 mounted in the resin case 7 in the direction of the arrow in FIG. Further, an enlarged view of the portion A of FIG. 4A is shown in FIG.

Here, when the pressing metal fitting 9 eliminates the looseness between the substrate 1 and the resin case 7 after being inserted and is fixed to the external heat radiation plate with a screw, the heat radiation surface 1c of the ceramic plate 1 is fixed. It is necessary to make contact with the external heat sink with a certain pressure or more. Further, similarly, for the purpose of such contact, the wall thickness 7c of the lower end portion of the board mounting groove 8 in the resin case 7 is made smaller than the protruding surface portion 1d of the board 1. The metal fitting 9 is attached to the resin case 7 by embedding it when molding the resin case 7.

5A and 5B show the resin case 7 of FIG.
3A and 3B are views showing the shape of the front side horizontal lid 7a, FIG. 3A is a top view thereof, and FIG. 2B is a side view thereof. Figure 5
As shown in (a), notches 7b are formed at both ends of the front lateral lid 7a to engage with one end surfaces of the board mounting grooves 8 on the left and right side walls of the resin case 7, and FIG. As shown in FIG. 3, a board mounting groove 8a is provided in the lower portion of the front side horizontal lid 7a similarly to the board mounting groove 8 of the resin case 7, and a holding metal fitting 9a is also mounted along the upper surface thereof.

Next, a method of assembling a module using these components will be described. First, the power element 3 is provided with the high melting point solder 2 on the pattern surface of the copper plate 1b on the substrate 1.
Fixed through, using ultrasonic bonding technology,
The electrode is taken out from the upper surface of the power element 3 to the surface of the copper plate 1b by the bonding wire 4. The processing up to this point is the same as the conventional example using a DBC substrate except that the type of substrate is different.

After that, the substrate 1 on which the power element 3 is mounted
The terminal holder 6 and the terminal holder 6 are fixed to each other with the low melting point solder 5 using a positioning jig. Then, the structure in which the board 1 and the terminal holder 6 are integrated is inserted into the resin case 7 shown in FIG. 3 through the board mounting groove 8 and mounted (see FIG. 4A).

In the assembly after the board 1 is inserted into the resin case 7 as described above, the resin case 7 is covered with the lateral cover 7a shown in FIG. At that time, the surfaces indicated by arrows in FIGS. 5A and 5B enter the inside of the resin case 7, and the board 1 is inserted into the board mounting groove 8a of the lateral lid 7a similarly to the board mounting groove 8 of the resin case 7. It will be.

After that, the substrate 1 and the resin case 7 and the resin case 7 and the lateral lid 7a are bonded and fixed using the adhesive 10, respectively.

Thereafter, as in the conventional example, the silicone resin gel agent 11 as the lower layer filler and the epoxy resin casting agent 12 as the upper layer filler are filled to seal the inside of the resin case 7.

FIG. 6 is a sectional view showing the structure of the main part of a high power semiconductor device according to the second embodiment of the present invention.

This embodiment is different from the first embodiment in that
In order to increase the mechanical strength of the lower end portion of the substrate mounting groove 8 provided in the lower portion of the resin case 7, a metal guide 21 such as steel is embedded in this portion. This metal guide 21 is similar to the metal fitting 7 in the resin case 7.
To be embedded when molding.

FIG. 7 is a sectional view showing the structure of the main part of a high power semiconductor device according to the third embodiment of the present invention.

This embodiment differs from the first embodiment in that
The point is that the pressing rod 31 is provided so as to traverse the inside of the resin case 7, and the pressing of the substrate 1 is performed not only around the inside of the resin case 7 but also by the pressing rod 31. This improves the strength of the resin case 7.

FIG. 8 is a sectional view showing the structure of a main portion of a high power semiconductor device according to the fourth embodiment of the present invention.

In this embodiment, the substrate 1 is the same DBC as the conventional one.
Instead of the substrate 41, the conventional substrate can be used as described above.

FIG. 9 is a sectional view showing the structure of a high power semiconductor device according to the fifth embodiment of the present invention.

In this embodiment, a ceramic material is used as a case material without using a resin. In this case, the substrate and the case are integrated by using the same material as the substrate ceramic material. The envelope 51 is manufactured. This eliminates the need for the press fitting.

FIG. 10 is a sectional view showing the structure of a high power semiconductor device according to the sixth embodiment of the present invention.

When mounting the module on the external heat dissipation plate, it is necessary to fix it with screws.
In the fifth embodiment, all the fixing parts by the screws are on the resin case 7 side. In contrast to this, the present embodiment has a structure in which the ceramic of the substrate is fixed with screws. That is, the substrate 1A is made of a ceramic that is larger than the resin case 7 in a form in which the resin case 7 is mounted on the upper surface side thereof, and an external heat dissipation plate is attached to an outer extending portion extending from the resin case 7 to the outside. A screw hole 13A for fixing is provided.

The thickness 61 of the substrate 1A directly below the power element 3 is a resistance component to heat radiation, and is therefore set to be less than a certain thickness. Further, the thickness of the portion (outer extending portion) 62 compressed by the screw in the substrate 1A is set to be thicker than that immediately below the power element 3 in order to enhance the mechanical strength.

Although the resin case 7 is provided as the envelope in the above-mentioned first to sixth embodiments, the present invention can be applied to, for example, a module in which the resin case 7 is omitted. .

[0050]

As described in detail above, the first to fourth aspects are provided.
According to the invention, since it is possible to omit the metal heat dissipation plate and the solder material for fixing the heat dissipation plate to the board, which is conventionally used for fixing the board, the life in the TFT test is significantly improved. It becomes possible. In addition, since the durability is excellent, the reliability in practical use is improved.

[Brief description of drawings]

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

2 is a cross-sectional view of the high thermal conductivity substrate 1 of FIG.

FIG. 3 is a perspective view showing the shape of a resin case 7 of FIG.

FIG. 4 is a diagram showing a state in which the substrate 1 is mounted in a resin case 7.

5 is a view showing the shape of a front side lid 7a of the resin case 7 of FIG.

FIG. 6 is a sectional view showing a main configuration of a high power semiconductor device according to a second embodiment of the invention.

FIG. 7 is a sectional view showing a main configuration of a high power semiconductor device according to a third embodiment of the present invention.

FIG. 8 is a sectional view showing a main configuration of a high power semiconductor device according to a fourth embodiment of the present invention.

FIG. 9 is a sectional view showing the structure of a high-power semiconductor device according to a fifth embodiment of the present invention.

FIG. 10 is a sectional view showing the structure of a high-power semiconductor device according to a sixth embodiment of the present invention.

FIG. 11 is a cross-sectional view showing a conventional module.

[Explanation of symbols]

 1a Ceramic plate 1b Copper plate 1,1A Substrate 3 Power element 6 Terminal holder 7 Resin case 8 Substrate mounting groove 9,9a Holding metal fitting 11 Silicon resin gel agent 12 Epoxy resin casting agent 13,13A Screw hole 21 Metal guide 31 Holding rod 41 DBC substrate 51 package

Claims (9)

[Claims] 1. A substrate comprising a ceramic plate having a reverse convex cross section, and a metal member formed on a main surface of the ceramic plate opposite to the convex surface side, and a power element mounted on the surface of the metal member of the substrate. A semiconductor device for high power, comprising: 2. An enclosure comprising a substrate on which a power element is mounted, a terminal holder electrically connected to the power element, and an envelope encasing the power element and the terminal holder. In a high-power semiconductor device in which a space inside the envelope formed by the substrate and the substrate is filled with resin so as to lead the terminal holder to the outside, a substrate mounting groove is formed in a lower portion inside a sidewall of the envelope. The high power semiconductor device is characterized in that the substrate is mounted in the substrate mounting groove to serve as a bottom lid of the envelope. 3. The substrate is configured such that a lower side of a peripheral end portion thereof is cut out so as to have an inverted convex cross-section, and the peripheral end portion of the substrate is mounted in the substrate mounting groove. Item 2. A high-power semiconductor device according to item 2. 4. The high power semiconductor device according to claim 2, wherein a pressing metal member for pressing the substrate is provided on an upper surface portion of the substrate mounting groove. 5. The substrate is composed of a ceramic member having a reverse convex cross section and a metal member formed on a main surface opposite to the convex side of the ceramic member, and the power element is provided on the surface of the metal member. 5. The high power semiconductor device according to claim 2, wherein the semiconductor device is mounted. 6. The high power semiconductor device according to claim 2, wherein a metal guide is embedded in a side wall of the envelope so as to be located at a lower side of the substrate mounting groove. 7. A screw hole for fixing an external housing is bored in an outer peripheral portion of the envelope extending from an outer wall surface of the envelope in a direction opposite to the substrate. 2 to claim 6
The high-power semiconductor device described. 8. A package having a substrate on which a power element is mounted, a terminal holder electrically connected to the power element, and an envelope encasing the power element and the terminal holder. In a high-power semiconductor device in which a resin is filled in a space inside the envelope formed by the substrate and the substrate so as to lead the terminal holder to the outside, the substrate is a bottom portion of the envelope. A semiconductor device for high power, wherein the semiconductor device is integrally formed with the envelope. 9. A package having a substrate on which a power element is mounted, a terminal holder electrically connected to the power element, and an envelope for casing the power element and the terminal holder. In a high-power semiconductor device in which a space formed inside the envelope formed by the substrate is filled with resin so as to lead the terminal holder to the outside, the substrate has the envelope mounted on its upper surface side. For large power, characterized in that it is formed in a larger size than the envelope, and a screw hole for fixing an external housing is bored in an outer extending portion extending from the envelope. Semiconductor device.