JP2002329828A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply coating resin with ease, check the state of the coating with ease, and prevent the occurrence of uncoated areas. SOLUTION: With respect to a semiconductor device 11, a projection 15a is formed on the upper face of the electrode block 15 thereof placed on one 13 of heat sinks, and a recess 14b to be engaged with the projection 15a is formed on the lower face of the other 14 of the heat sinks. Coating resin 17 is applied to faces of the heat sinks 13 and 14 and the like to be brought into contact with resin 18 to enhance the adhesion to the resin 18. Thus, even if the coating resin is applied before the other heat sink 14 is joined with the electrode block 15, some areas are prevented from being left uncoated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device comprising a heating element and a pair of heat radiating plates joined to both sides of the heating element, and a method of manufacturing the same.

[0002]

2. Description of the Related Art For example, a semiconductor chip (heat generating element) for a high withstand voltage and a large current generates a large amount of heat when used, so that a structure for improving heat dissipation from the chip is required. As an example of this configuration, a configuration in which a pair of heat radiating plates are joined to both surfaces of a chip via, for example, a solder layer has been conventionally considered. According to this configuration, heat can be radiated from both surfaces of the chip, so Is improved.

An example of a semiconductor device having the above configuration is shown in FIG.
Shown in As shown in FIG. 5, the semiconductor device 1 includes a semiconductor chip 4 between a pair of heat sinks (radiator plates) 2 and 3.
And the electrode block 5. Between the heat sink 2 and the semiconductor chip 4, between the semiconductor chip 4 and the electrode block 5, and between the electrode block 5 and the heat sink 3,
Each is joined by solder 6. The semiconductor device 1 having such a configuration is molded with the resin 7.

[0004]

In the above conventional structure, the semiconductor chip 4, the heat sinks 2, 3 and the like and the resin 7
Is large, a large thermal stress acts on the contact portion between the two, and if the thermal stress is larger than the adhesive force of the resin 7, the resin 7 may be peeled off. When the resin 7 is peeled off, a large stress is applied to the joint (solder layer) between the semiconductor chip 4 and the heat sinks 2 and 3, and the joint (solder layer) is rapidly deteriorated. This tendency is more remarkable as the temperature difference is larger.

[0005] As a measure for preventing the resin 7 from peeling off, a measure for increasing the adhesion of the resin 7 can be considered. As a countermeasure, for example, a polyamide resin 8 which is a coating resin for improving adhesion to the resin 7 is provided on the surface to which the resin 7 adheres, that is, the upper surface of the heat sink 2, the lower surface of the heat sink 3, and the surfaces of the semiconductor chip 4 and the electrode block 5. (FIG. 5
It is considered to apply a slightly thick solid line in the drawing).

Here, when the polyamide resin 8 is to be applied in a state immediately before resin molding, that is, in a state in which the semiconductor chip 4 and the electrode block 5 are soldered between the pair of heat sinks 2 and 3, Two, three
Is only about 1 to 2 mm, for example, and is considerably narrow, so that it was difficult to apply the polyamide resin 8 uniformly without leakage.

Therefore, the inventor of the present invention, as shown in FIG.
With respect to a configuration in which the semiconductor chip 4 and the electrode block 5 are soldered on the heat sink 2, a method of applying a polyamide resin 8 before soldering the heat sink 3 was considered. Specifically, the semiconductor chip 4 is placed on the heat sink 2.
The polyamide resin 8 was applied to the upper surface of the structure where the electrode block 5 was soldered and the polyamide resin 8 was applied to the lower surface of the heat sink 3. In this case, the electrode block 5
The upper surface of the heat sink 3 and the portion of the lower surface of the heat sink 3 where the electrode block 5 is joined are masked so that the polyamide resin 8 is not applied.

Then, as described above, the polyamide resin 8
Then, the lower surface of the heat sink 3 is soldered to the upper surface of the electrode block 5. Thereby, the resin 7
Thus, the configuration before molding is obtained (see FIG. 5). However, in the case of this configuration, there is a disadvantage that a portion where the polyamide resin 8 is not applied is inevitably formed in a portion where the electrode block 5 of the heat sink 3 is soldered. When such an uncoated portion exists, the adhesion between the mold resin 7 and the heat sinks 2 and 3 cannot be sufficiently ensured, and the resin 7 may be peeled off by thermal stress generated when heated and cooled. .

Therefore, it is necessary to re-apply the unapplied portion. In this re-applying operation, since the gap between the heat sinks 2 and 3 is narrow, the workability is also poor, and it is difficult to confirm the applied state. There is a problem.

Accordingly, an object of the present invention is to provide a semiconductor device in which a coating resin can be easily applied, the applied state can be easily confirmed, and the occurrence of an uncoated portion can be prevented. And a method for manufacturing the same.

[0011]

According to the first aspect of the present invention, a fitting portion comprising a convex portion or a concave portion is provided on the upper surface of the electrode block, and the fitting portion is fitted on the lower surface of the other heat sink. A fitting portion comprising a concave portion or a convex portion is provided on the surface of the radiating plate, and a coating resin for improving the adhesiveness with the resin is applied to a surface of the surface of the heat sink or the like which comes into contact with the resin. In this configuration, if the coating resin is applied before the other heat sink is joined to the electrode block, the coating resin can be easily applied and the applied state can be easily confirmed. Can be. Then, after the application, when joining the other heat sink to the electrode block, the fitting portion of the electrode block is fitted to and joined to the fitted portion of the other heat sink. The coating layer of the polyamide resin applied to the surface of the heat sink comes into direct contact with each other, so that it is possible to prevent the generation of the uncoated portion of the polyamide resin.

According to the second aspect of the invention, when the fitting portion is a convex portion and the fitted portion is a concave portion, or the fitting portion is a concave portion and the fitted portion is a convex portion. At this time, since the depth of the recess is configured to be slightly larger than the projection of the projection, the projection can be joined to the recess via a joining member (solder or the like).

According to the third aspect of the present invention, a step of joining a heating element on one heat sink and joining an electrode block on the heating element, and joining the heating element and the electrode block to each other. A step of applying a coating resin on the upper surface of the one heat radiating plate to improve the adhesion to the resin except for a fitting portion formed of a convex portion or a concave portion provided on the upper surface of the electrode block; A step of applying the coating resin to a lower surface of the plate except for a fitting portion formed of a concave portion or a convex portion provided on the lower surface of the heat sink so as to fit with the fitting portion; And the step of fitting and joining the fitting part of the other heat sink to the fitting part of the other heat sink. Therefore, the same function and effect as the invention of claim 1 can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. First,
As shown in FIG. 1, a semiconductor device 11 of this embodiment includes a semiconductor chip (heating element) 12, a lower heat sink (one heat sink) 13, an upper heat sink (other heat sink) 14, and a heat sink block. (Electrode block) 1
5 is provided.

The semiconductor chip 12 is, for example, an IGBT
And a power semiconductor element such as a thyristor. In the case of the present embodiment, the shape of the semiconductor chip 12 is as shown in FIG.
As shown in (a), the shape is, for example, a rectangular thin plate. The lower heat sink 13, the upper heat sink 14, and the heat sink block 15 are made of a metal having high thermal conductivity and high electrical conductivity, such as Cu or Al.

The lower heat sink 13 is connected to the lower heat sink 13 as shown in FIG.
As shown in (a), for example, it is a substantially rectangular plate material as a whole, and the terminal portion 13a is provided so as to protrude rearward. Also, the upper heat sink 14 is shown in FIG.
As shown in (d), the terminal portion 14a is formed of, for example, a substantially rectangular plate as a whole, and the terminal portion 14a is provided so as to protrude rearward. This upper heat sink 14
As shown in FIG. 1 and FIG. 3, a concave portion 14b, which is a portion to be fitted, is formed on the lower surface of.

Further, the heat sink block 15 is provided as shown in FIG.
As shown in FIG. 1A, a rectangular plate having a size about one size smaller than the semiconductor chip 12 is used. On the upper surface of the heat sink block 15, for example, a rectangular convex portion 15a which is a fitting portion is formed.

In the case of the above configuration, as shown in FIG. 1, the semiconductor chip 12 is joined to the lower heat sink 13 via a joining member, for example, a solder 16. The heat sink block 15 is joined to the semiconductor chip 12 via a joining member, for example, a solder 16.

Further, the upper heat sink 14 is provided on the heat sink block 15 with a bonding member such as a solder 16.
Are joined through. In this case, the heat sink block 1 is provided in the concave portion 14b on the lower surface of the upper heat sink 14.
5 is fitted with the convex portion 15a on the upper surface, and the concave portion 1
The solder 16 is joined between the inner bottom surface of 4b and the upper surface of the projection 15a. In addition, as described above, the heat sink block 1
The reason why the projections 15a are provided on the upper surface 5 and the recesses 14b are provided on the upper heat sink 14 will be described later in a method of manufacturing the semiconductor device 11.

In the above configuration, heat is radiated from both surfaces of the semiconductor chip 12 through the heat sinks 13 and 14 (and the heat sink block 15). The lower heat sink 13 and the upper heat sink 14 are also electrically connected to respective main electrodes (for example, a collector electrode and an emitter electrode) of the semiconductor chip 12 via solder 16.

The terminal 13a of the lower heat sink 13
And the terminal portions 14a of the upper heat sink 14 are configured so as to be displaced from each other, that is, not to face each other. Further, in the case of the above configuration, the distance between the upper surface of the lower heat sink 13 and the lower surface of the upper heat sink 14 is configured to be, for example, about 1 to 2 mm.

On the other hand, as shown in FIG.
A coating resin, for example, a polyamide resin 17 is applied to the surfaces of the chips 3 and 14 and the peripheral portions of the chip 12 and the heat sink block 15 as indicated by a slightly thick solid line. The method of applying the polyamide resin 17 will be described later in a method of manufacturing the semiconductor device 11.

Further, as shown in FIG. 1, a resin (for example, epoxy resin) 18 is molded (filled and sealed) in the gap between the pair of heat sinks 13 and 14 and around the chip 12 and the heat sink block 15. Have been.
In this case, due to the coating layer of the polyamide resin 17, the adhesive force between the resin 18 and the heat sinks 13 and 14, the adhesive force between the resin 18 and the chip 12, and the resin 1
The adhesion between the heat sink block 8 and the heat sink block 15 is enhanced.

The lead frames 19a and 19b (see FIGS. 1 and 2) wire-bonded to control electrodes (eg, gate pads) of the chip 12 are also molded with the resin 18. The wires 20 connecting the lead frames 19a, 19b and the control electrodes of the chip 12 are, for example, wires made of Al, Au, or the like. Further, the wires 20 and the lead frames 19a, 19
The surface of b is also coated with a polyamide resin 17 (not shown in FIG. 1).

Next, a method of manufacturing the semiconductor device 11 having the above-described configuration (ie, a manufacturing process) will be described with reference to FIG. First, as shown in FIGS. 2A and 2B, a step of soldering the semiconductor chip 12 and the heat sink block 15 to the upper surface of the lower heat sink 13 is performed.
In this case, the chip 12 is mounted on the upper surface of the lower heat sink 13 via the solder foil 21, and the heat sink block 15 is mounted on the chip 12 via the solder foil 21. After that, the solder foils 21 are melted by a heating device (reflow device) and then cured.

Subsequently, as shown in FIG. 2C, a step of wire bonding the control electrodes (eg, gate pads, etc.) of the chip 12 to the lead frames 19a, 19b is performed. Thus, the control electrode of the chip 12 and the lead frames 19a and 19b are connected by the wire 20.

Next, before the upper heat sink 14 is soldered on the heat sink block 15, a step of applying a polyamide resin 17 to the heat sinks 13, 14 and the heat sink block 15 is performed before that.
In this case, when the polyamide resin 17 is applied to the surface (upper surface) of the structure in which the semiconductor chip 12 and the heat sink block 15 are soldered to the lower heat sink 13, as shown by a somewhat thick solid line in FIG. A polyamide resin 17 is applied to the surface of the block 15 excluding the protrusions 15a. At this time, the polyamide resin 17 is also applied to the surfaces of the wires 20 and the lead frames 19a and 19b.

The protrusion 15 of the heat sink block 15
In order to prevent the polyamide resin 17 from being applied to a or the like, the convex portion 15a may be masked by a known method.
In addition, as a specific method of applying the polyamide resin 17, an application method in which the polyamide resin is dropped or sprayed from a nozzle of a dispenser for applying the polyamide resin, a dipping application method, or the like may be used.

When the polyamide resin 17 is applied to the surface (lower surface) of the upper heat sink 14,
As shown by a somewhat thick solid line in FIG.
7 is applied. The concave portion 14b of the upper heat sink 14
In order not to apply polyamide resin 17 to
The recess 14b may be masked by a known method. Further, as a specific method of applying the polyamide resin 17, the above-described application method may be appropriately used.

After that, when the applied polyamide resin 17 is dried, a step of soldering the upper heat sink 14 on the heat sink block 15 is executed as shown in FIG. In this case, as shown in FIG. 2D, the upper heat sink 14 is placed on the heat sink block 15 via the solder foil 21. That is, the convex portion 15a of the heat sink block 15 is
B is fitted with the solder foil 21 interposed therebetween. Then, after the solder foil 21 is melted by a heating device, it is cured.

At this time, for example, a weight or the like (not shown) is placed on the upper heat sink 14 so as to press the upper heat sink 14 downward. At the same time, a spacer jig (not shown) is provided between the upper heat sink 14 and the lower heat sink 13.
Is attached, the distance between the upper heat sink 14 and the lower heat sink 13 is maintained at a predetermined set distance.

In the state before the solder foil 21 is melted,
The distance between the upper heat sink 14 and the lower heat sink 13 is configured to be larger than the set distance of the spacer jig. When the solder foil 21 is melted, the melted solder layer becomes thinner due to a pressing force such as weight.
The distance between the upper heat sink 14 and the lower heat sink 13 is equal to the set distance of the spacer jig. At this time, the solder layer is configured to be thinned to an appropriate thickness. When the molten solder layer is cured, the chip 12
And heat sinks 13 and 14 and heat sink block 15
Bonding and electrical connection are completed.

Further, in the above configuration, as shown in FIG. 3, since the projection 15a of the heat sink block 15 is fitted into the recess 14b of the upper heat sink 14 and joined, as shown in FIG. In addition, the coating layer of the polyamide resin 17 on each surface of the heat sink block 15 and the upper heat sink 14 comes into direct contact with each other, thereby preventing the uncoated portion of the polyamide resin 17 from being generated. Further, in the case of the above configuration, as shown in FIG. 3, since the depth A of the recess 14b is configured to be slightly larger than the projection B of the projection 15a, the projection 15a is formed on the inner bottom of the recess 14b. The upper surface can be joined via 16 layers of solder as joining members. The dimensions A and B are set so that the thickness of the 16 layers of solder is a thickness having a sufficient bonding strength and is as thin as possible.

Next, as shown in FIG.
A step of molding the gap between 3 and 14 and the peripheral portions of the chip 12 and the heat sink block 15 with the resin 18 is performed. In this case, the heat sink 13 soldered and coated with the polyamide resin 17 as described above,
The components such as 14, the chip 12, the heat sink block 15, and the like are accommodated in a molding die (not shown), and a resin 18 is injected (filled). Thereby, the resin 18 is filled into the gap between the pair of heat sinks 13 and 14 and the peripheral portions of the chip 12 and the heat sink block 15. Then, after the resin 18 is cured, the semiconductor device 11 is taken out of the mold to complete the semiconductor device 11.

In the present embodiment having such a structure, the convex portion (fitting portion) 15 a is formed on the upper surface of the heat sink block 15.
And a concave portion (fitted portion) 14b is provided on the lower surface of the upper heat sink 14 so as to fit with the convex portion 15a, and the heat sinks 13 and 14 and the semiconductor chip 1 are provided.
2 and the like, the surface of the resin 18
A polyamide resin (coating resin) 17 for improving the adhesiveness with the resin is applied.

According to this configuration, the upper heat sink 14
When the application of the polyamide resin 17 is performed as shown in FIG. 3 in a state before bonding the polyamide resin 17 to the heat sink block 15, the polyamide resin 17 can be easily applied, and (E.g., the presence or absence of application leakage and the degree of application unevenness) can be easily confirmed.
When the upper heat sink 14 is joined to the heat sink block 15 after the application of the polyamide resin 17, the protrusion 15 a of the heat sink block 15 is fitted into the recess 14 b of the upper heat sink 14 and soldered. The coating layer of the polyamide resin 17 on each surface of the block 15 and the upper heat sink 14 comes into direct contact (see FIG. 1). Therefore, unlike the conventional configuration (see FIG. 5), the generation of the uncoated portion of the polyamide resin 17 can be almost certainly prevented.

In the above embodiment, the depth A of the recess 14b of the upper heat sink 14 is configured to be slightly larger than the projection B of the projection 15a of the heat sink block 15. 15a can be joined via the solder 16 (joining member), and the joining strength can be sufficient. Further, in the case of the above embodiment, the heat sink block 15 and the upper heat sink 1
4 ensures that the coating layer of the polyamide resin 17 on each surface directly abuts.

In the above embodiment, the pair of heat sinks 13 and 14 and the chip 12 and the like
7, so that the heat sink 13,
The adhesive strength between the resin 14, the chip 14, and the like can be increased.

In the above embodiment, the heat sink block 15 is provided with the protrusion 15a and the upper heat sink 14 is provided with the recess 14b.
Alternatively, the heat sink block 15 may be provided with a concave portion and the upper heat sink 14 may be provided with a convex portion.

Further, the solder foil 21 is used as a joining member for joining the heat sinks 13, 14, the chip 12, the heat sink block 15, and the like. However, the present invention is not limited to this. Is also good. In the above embodiment, the polyamide resin 17 is applied as the coating resin. However, the present invention is not limited to this, and any other resin having a function of increasing the adhesion between the heat sinks 13 and 14 and the resin 18 may be used. Resin may be used.

FIG. 4 shows a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals. In the second embodiment, as shown in FIG. 4, the polyamide resin 17 is applied to the surfaces of the end faces of the heat sinks 13 and 14.

The other structure of the second embodiment is the same as that of the first embodiment. Therefore, in the second embodiment, substantially the same operation and effect as in the first embodiment can be obtained. In particular, according to the second embodiment, the adhesion between the heat sinks 13 and 14 and the resin 18 can be further increased.

In the above embodiments, the polyamide resin 17 may be applied to the surfaces of the lead frames 19a and 19b. With this configuration, the adhesion between the lead frames 19a and 19b and the resin 18 can be further increased.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a view showing a manufacturing process of the semiconductor device;

FIG. 3 is an exploded longitudinal sectional view of the semiconductor device.

FIG. 4 is a view corresponding to FIG. 1, showing a second embodiment of the present invention;

FIG. 5 is a diagram corresponding to FIG. 1 showing a conventional configuration.

FIG. 6 is a diagram corresponding to FIG. 3;

[Explanation of symbols]

11 is a semiconductor device, 12 is a semiconductor chip, 13 is a lower heat sink (one heat sink), 14 is an upper heat sink (the other heat sink), 14b is a concave portion (fitted portion), 15 is a heat sink block (electrode block). ), 15a are convex portions (fitting portions), 16 is solder, 17 is polyamide resin (coating resin), and 18 is resin.

Claims (3)

[Claims] 1. A heat radiating plate, a heating element joined on the heat radiating plate, an electrode block joined on the heating element, and another heat radiating plate joined on the electrode block. A semiconductor device formed by molding a resin between the two heat radiating plates, a fitting portion comprising a convex portion or a concave portion provided on an upper surface of the electrode block, and a fitting portion formed on a lower surface of the other heat radiating plate. A fitting portion formed of a concave portion or a convex portion provided so as to be fitted to the mating portion, and a coating resin applied to a surface of the surface of the heat sink or the like that comes into contact with the resin to enhance adhesion to the resin A semiconductor device comprising: 2. When the fitting portion is a convex portion and the fitted portion is a concave portion, or when the fitting portion is a concave portion and the fitted portion is a convex portion, 2. The semiconductor device according to claim 1, wherein a depth dimension of the recess is slightly larger than a projection dimension of the projection. 3. A step of joining a heating element on one of the heat sinks and joining an electrode block on the heating element; and a step of joining the one heat sink to which the heating element and the electrode block are joined. Applying a coating resin on the upper surface to improve the adhesion to the resin except for a fitting portion formed of a convex portion or a concave portion provided on the upper surface of the electrode block; A step of applying the coating resin except for a fitting portion formed of a concave portion or a convex portion provided on the lower surface of the plate so as to fit with the fitting portion; Fitting and joining the fitted portion of the heat sink to the semiconductor device.