JP2009277959A - Semiconductor device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device and its manufacturing method, which prevents adhesion of a resin burr on external electrodes without lowering productivity. <P>SOLUTION: An IGBT 16 (semiconductor chip) and external electrodes 24 are electrically connected. A housing 30 seals the IGBT 16 in such a way that a part of each external electrode 24 is led out to the outside. Each external electrode 24 has a through-hole 34 at the base of the part led out from the housing 30. A thermoplastic resin that constitutes the housing 30 is filled in at least a part of the through-hole 34. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor device in which an external electrode is led out from a casing of a thermoplastic resin and a method for manufacturing the same, and particularly to a semiconductor device capable of preventing resin burrs from adhering to the external electrode without reducing productivity. It relates to a manufacturing method.

  Resin-encapsulated semiconductor devices can reduce the case connection and gel encapsulation processes compared to case-type semiconductor devices that use resin cases with external electrodes attached, and also have vibration resistance. Are better. For the production of a resin-encapsulated semiconductor device, an injection mold using a thermoplastic resin such as PPS, a transfer mold using a thermosetting resin, or the like is used. The molding time of the injection mold is approximately 30 seconds, which is approximately one fifth of that of the transfer mold. And since the injection mold does not require curing for completing the curing of the resin, it is highly productive.

  In the injection mold, when the resin is filled into the molding die, the inside of the molding die becomes a high pressure with the filling pressure set by the molding machine. At this stage, resin is pushed into the gap between the lead-out portion of the external electrode and the molding die, and resin burrs adhere to the external electrode. The external electrode is a terminal for current input / output, and may be energized with several hundreds of A. For this reason, when the resin burr | flash which is an insulator has adhered to the external electrode, contact resistance will increase, an increase in power loss and abnormal heat generation will generate | occur | produce.

  Therefore, it is necessary to remove resin burrs. However, since thin resin burrs are difficult to remove, it is desirable to prevent resin burrs during molding. As such a resin burr prevention method, a method of suppressing fluidity by lowering the resin molding temperature has been proposed (see, for example, FIGS. 1 and 3 of Patent Document 1).

Japanese Patent Laid-Open No. 9-232349

  In the method of Patent Document 1, heat treatment is required after molding. Such post-treatment such as heat treatment and resin deburring has a problem that the manufacturing time becomes long and the productivity is lowered.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a semiconductor device capable of preventing resin burrs from adhering to an external electrode without reducing productivity, and a method for manufacturing the same. Is what you get.

  A semiconductor device according to the present invention includes a semiconductor element, an external electrode electrically connected to the semiconductor element, and a thermoplastic resin in which the semiconductor element is sealed so that a part of the external electrode is led out to the outside. The external electrode is provided with a through hole at the root of a portion derived from the housing, and at least a part of the through hole is filled with the thermoplastic resin constituting the housing Has been.

  The method of manufacturing a semiconductor device according to the present invention includes a step of electrically connecting an external electrode provided with a through hole to a semiconductor element, and a step of inserting the semiconductor element into a cavity of a molding die. And a step of injecting a thermoplastic resin into the cavity to seal the semiconductor element, and when the semiconductor element is sealed, the through hole is formed at the outer edge of the cavity. The thermoplastic resin is filled in at least a part of the through hole.

  According to the present invention, it is possible to prevent the resin burrs from adhering to the external electrode without reducing the productivity.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing an outer shape of the semiconductor device according to the first embodiment, and FIG. 2 is a perspective view showing an internal structure of the semiconductor device according to the first embodiment. 3 is a cross-sectional view taken along the line II of FIG. 1, and FIG. 4 is a cross-sectional view taken along the line II-II of FIG.

  The heat radiating plate 10 is 40 mm long × 60 mm wide and 2 mm thick, and is made of a high heat conductive material based on aluminum. A ceramic plate 12 is mounted on the heat sink 10. The ceramic plate 12 is made of a material having a relatively high thermal conductivity such as alumina, aluminum nitride, or silicon nitride. On the ceramic plate 12, a copper pattern 14a having a thickness of 0.3 mm constituting a circuit of the power semiconductor device is formed. Similarly, a copper pattern 14 b is formed on the back surface of the ceramic plate 12. The copper pattern 14b on the back surface and the heat radiating plate 10 are fixed by a connection method with high heat dissipation such as soldering.

  An IGBT 16 (semiconductor element) and a free wheel diode 18 are mounted on the ceramic plate 12. The IGBT 16 has a length of 7.5 mm × width of 9 mm, a thickness of 250 μm, a gate electrode and an emitter electrode on the surface, and a collector electrode on the back surface. The freewheel diode 18 has a length of 4 mm × width of 9 mm and a thickness of 250 μm, and has an anode electrode on the front surface and a cathode electrode on the back surface.

  The collector electrode of the IGBT 16 and the cathode electrode of the free wheel diode 18 are connected to the copper pattern 14a via solder based on Sn—Ag—Cu or the like. The emitter electrode of the IGBT 16 and the anode electrode of the free wheel diode 18 are connected to the copper pattern 14a via a lead 20 made of copper having a thickness of 0.3 mm. The gate electrode of the IGBT 16 is connected to the copper pattern 14 a via the aluminum wire 22.

  The external electrode 24 and the signal electrode 26 are connected to the copper pattern 14a by soldering or the like. That is, the IGBT 16 and the external electrode 24 are electrically connected through the copper pattern 14a. The external electrode 24 is a copper plate having a thickness of about 0.8 mm, and inputs and outputs a current of 100 A or less with an external device. The signal electrode 26 is a thin electrode of about 0.5 mm □, and inputs and outputs a small current for operating the semiconductor element. Since such a thin signal electrode 26 is difficult to support only by soldering, the distance between the signal electrodes 26 is maintained using a member 28 having heat resistance up to the soldering temperature.

  The housing 30 seals the IGBT 16 and the like so that part of the external electrode 24 and the signal electrode 26 is led out to the outside. The housing 30 is made of a thermoplastic resin such as PPS (polyphenylene sulfide) or PBT (polybutylene terephthalate) whose strength is improved by blending glass fibers. The height from the rear surface of the heat sink 10 to the location where the external electrode 24 of the housing 30 is led out is 17 mm, and the outer shape of the housing 30 is 45 mm long × 80 mm wide.

  The heat generated by the IGBT 16 and the free wheel diode 18 is radiated from the back surface of the heat radiating plate 10 to a heat sink (not shown) via a heat radiating auxiliary member (not shown) such as silicone grease. Therefore, in order to ensure heat exchange between the heat radiating plate 10 and the heat sink, the housing 30 is formed with a hole 32 for screwing the heat sink.

  The external electrode 24 is provided with a through hole 34 having a diameter of 2 mm at the root of a portion (leading portion) led out from the housing 30. At least a part of the through hole 34 is filled with a thermoplastic resin constituting the housing 30. The external electrode 24 is bent at the portion of the through hole 34, and the tip of the external electrode 24 is substantially parallel to the upper surface of the housing 30. A nut 40 is inserted into the hole 36 of the external electrode 24 and the hole 38 of the housing 30, and the external electrode 24 is screwed.

  A method for manufacturing a semiconductor device according to the present embodiment will be described. First, a process such as electrically connecting the external electrode 24 provided with the through hole 34 to the IGBT 16 is performed to form the structure shown in FIG.

  Next, as shown in FIG. 5, a part of the external electrode 24 is led out of the cavity 44 with the IGBT 16 and the like placed in the cavity 44 of the molding die 42. At this time, the through hole 34 is disposed on the outer edge of the cavity 44.

  Next, as shown in FIG. 6, the housing 30 is formed by injecting a thermoplastic resin into the cavity 44 and sealing the IGBT 16 and the like by an injection molding method. At this time, a part of the external electrode 24 and the signal electrode 26 and the back surface of the heat sink 10 are exposed. Further, at least a part of the through hole 34 is filled with a thermoplastic resin. Thereafter, the semiconductor device according to the present embodiment is manufactured through processes such as bending the external electrode 24.

  Here, at the time of molding, the through hole 34 is filled with the thermoplastic resin at an early stage. The thermoplastic resin is deprived of heat by the molding die 42 so that the flow rate gradually decreases and is eventually solidified. Therefore, the resin is sufficiently solidified at the base of the lead-out portion of the external electrode 24 when the filling pressure of the resin in the cavity 44 increases. Thereby, since it can suppress that resin is pushed into the clearance gap between the derivation | leading-out part of the external electrode 24, and the shaping die 42, it can prevent that the resin burr | flash adheres to the external electrode 24. FIG. Further, since post-treatment such as heat treatment and resin deburring is unnecessary, productivity is not reduced.

  Further, the pressure applied to the front and back surfaces of the external electrode 24 during molding is made uniform by the through holes 34. The dispersion of pressure in this way also contributes to the suppression of the generation of resin burrs.

  Further, since the external electrode 24 is firmly supported by the resin in the through hole 34, the external electrode 24 can be bent relatively easily at the portion where the through hole 34 is formed, and the bent shape of the external electrode 24 is stabilized. When the resin passes through the through hole 34, the glass fibers mixed with the resin are aligned, so that the strength of the housing 30 is increased. Therefore, when screwing a crimp terminal of a cable from another facility or power source to the external electrode 24, for example, when an automatic screw tightening device is used for shortening the process, the tightening force momentarily larger than the specified value is used. Even if added, the housing 30 is difficult to break.

  In addition, since thermoplastic resins such as PPS and PBT have low adhesion to metal, there is a concern that moisture may enter the housing 30 from the lead-out portion of the external electrode 24. On the other hand, by providing the through hole 34 in the external electrode 24, the compressive stress due to the curing shrinkage of the resin at the time of molding can be maintained, so that the moisture intrusion path is reduced and the reliability is improved.

  The shape and size of the through hole 34 can be freely selected according to the thickness of the external electrode 24, the gap with the molding die, and the viscosity of the resin to be used in consideration of the electrical resistance and strength of the external electrode 24. be able to. The viscosity of the resin increases as it contains more filler such as glass fiber. When using resin with high viscosity, the through hole 34 is enlarged. For example, when a 300 Pa · s resin is used, one through hole 34 having a diameter of 3 to 4 mm is formed. On the other hand, when a resin having a low viscosity, for example, 100 Pa · s, is used, a plurality of small through holes 34 having a diameter of about 1 mm are arranged as shown in FIG. Resin having a low viscosity can be sufficiently introduced even through the small through hole 34. In addition, if a resin having a low viscosity is used, resin burrs are likely to occur, but the occurrence of resin burrs can be suppressed by reducing the interval between the through holes 34. Further, as shown in FIG. 8, the through hole 34 may be oval or rectangular. Thereby, the area of the external electrode 24 becomes small at the bent portion, and the occurrence of resin burrs can be further suppressed.

  Moreover, although the screwing electrode is used as the external electrode 24, the present invention is not limited thereto, and a soldering electrode or a pressure contact electrode may be used. Even in these cases, the same effect can be obtained by preventing the resin burr from adhering to the external electrode 24.

  Further, the circuit of the copper pattern 14a may be coated with an epoxy or silicone resin. As a result, the withstand voltage and reliability are improved, and moisture can be prevented from entering from the external electrode 24.

  Moreover, although the ceramic board | substrate with which the copper patterns 14a and 14b were formed in the front and back of the ceramic board 12 was used, you may use not only this but a metal base board | substrate. Instead of mounting the ceramic plate 12 on the heat sink 10, the copper pattern 14 a may be bonded on the heat sink 10 using a mixture of a highly heat conductive filler in an adhesive epoxy insulating layer.

  Further, the semiconductor device is not limited to a power semiconductor device using an IGBT as a semiconductor element, and may be a MOSFET module or a diode module, for example. The material constituting the housing 30 is not limited to PPS and PBT, and LCP (liquid crystal polymer) may be used. In addition, various modifications can be made without departing from the effects of the present invention. These changes can be similarly applied to the following embodiments.

Embodiment 2. FIG.
FIG. 9 is a cross-sectional view showing the semiconductor device according to the second embodiment. 9 corresponds to a cross-sectional view taken along II-II in FIG. Since the external shape of the power semiconductor device is almost the same as that of the first embodiment, description thereof is omitted.

  The housing 30 is provided with a convex portion 46 that partially protrudes from the housing 30 and covers the periphery of the through hole 34 of the external electrode 24. The convex part 46 exists in the area | region of the through-hole 34, and becomes thin toward the outer side from the inner side of the housing | casing 30. As shown in FIG. Further, the convex portion 46 is configured at an angle of about 40 degrees with respect to the plane of the housing 30. In the case of 20 degrees or less, it is necessary to flatten a part of the tip in order to prevent the tip from being lost when the external electrode 24 is bent.

  When manufacturing the semiconductor device according to the present embodiment, a molding die as shown in FIG. 10 is used. The molding die 42 is provided with a recess 48 that narrows from the inside to the outside of the cavity 44 around the through hole 34 of the external electrode 24. Other configurations are the same as those of the first embodiment.

  Here, when a large current of 300 A or more is applied to the external electrode 24, the power loss in the external electrode 24 increases, and thus the area of the through hole 34 cannot be increased. Therefore, in the present embodiment, a recess 48 is formed around the through hole 34 to improve the resin filling property into the through hole 34. Accordingly, even when a resin having a high viscosity is used, it is possible to prevent the resin burr from adhering to the external electrode 24.

  It is also effective to form the recess 48 of the molding die 42 on the side close to the gate for injecting resin into the cavity 44. However, in consideration of the balance of the amount of resin, it is preferable to form it on both sides of the through hole 34.

  Moreover, since the convex part 46 of the housing | casing 30 can be used for positioning of the crimp terminal of the cable connected to the external electrode 24, assembly property improves. In the case where the convex portion 46 interferes due to the size of the crimp terminal or the wiring direction of the cable, in order to prevent the convex portion 46 from protruding from the surface of the external electrode 24, The height of the protruding through hole 34 may be set to be equal to or less than the thickness of the external electrode 24.

  Further, since the convex portion 46 of the housing 30 covers the periphery of the through hole 34, the strength of the housing 30 against the deformation of the external electrode 24 is increased as compared with the first embodiment. Therefore, even when the external electrode 24 having a thickness exceeding 1 mm is used in order to cope with a large current, the casing 30 can be prevented from cracking.

  Further, the convex portion 46 of the housing 30 is preferably present in the region of the through hole 34 so as not to interfere when the external electrode 24 is bent. However, since it is absorbed by the bending R of the external electrode 24, the convex portion 46 may exist outside the region of the through hole 34 as long as it is the thickness of the external electrode 24.

Embodiment 3 FIG.
FIG. 11 is a perspective view showing the outer shape of the semiconductor device according to the third embodiment, and FIG. 12 is a cross-sectional view taken along line III-III in FIG. Since the outer shape of the power semiconductor device is substantially the same as that of the first embodiment except for the vicinity of the root of the lead-out portion of the external electrode 24, description thereof is omitted.

  A region including a convex portion 46 of about 2 mm in the vicinity of a portion from which the external electrode 24 of the housing 30 is led sinks inward by about 1 mm from the surface of the housing 30.

  When manufacturing the semiconductor device according to the present embodiment, a molding die as shown in FIG. 13 is used. The molding die 42 protrudes toward the inside of the cavity 44 in a region including a recess 48 in the vicinity of a portion from which the external electrode 24 is led out. Other configurations are the same as those of the second embodiment.

  Here, in the case of the second embodiment, the convex portion 46 may interfere when the external electrode 24 is bent due to problems such as resin fluidity, the thickness of the external electrode 24, and position accuracy. On the other hand, in the present embodiment, the region including the convex portion 46 in the vicinity of the portion from which the external electrode 24 of the housing 30 is led sinks inward from the surface of the housing 30. When the electrode 24 is bent, the protrusion 46 can be prevented from interfering.

  Further, when the casing 30 is molded, the external electrode 24 and the molding die 42 need to be positioned. In particular, when the external electrode 24 is soldered on the ceramic plate 12, the positional accuracy is not good, and a positional deviation of about plus or minus 0.5 mm must be allowed in consideration of the dimensional tolerance of the member. However, if a gap of 0.5 mm is formed between the molding die 42 and the external electrode 24, a resin burr having a thickness of 1 mm at maximum is generated. On the other hand, the molding die 42 according to the present embodiment has a structure in which the external electrode 24 can be easily guided into the hole therefor, so that the soldering position accuracy of the external electrode 24 is allowed to about ± 1 mm, and manufacturing is easy. Become.

  In order to exert such an effect, it is preferable that the protrusion of the molding die 42 to the inside of the cavity 44 is equal to or greater than the thickness of the external electrode 24. The inclination angle of the recess 48 of the molding die 42 is as large as 45 degrees when the external electrode 24 is as thick as 1 mm or more, and as small as 30 degrees when the external electrode 24 is thin. And damage to the internal electric circuit can be suppressed.

1 is a perspective view showing an outer shape of a semiconductor device according to a first embodiment. 1 is a perspective view showing an internal structure of a semiconductor device according to a first embodiment. It is sectional drawing in II of FIG. It is sectional drawing in II-II of FIG. 8 is a cross-sectional view for illustrating the method for manufacturing the semiconductor device according to the first embodiment. FIG. 8 is a cross-sectional view for illustrating the method for manufacturing the semiconductor device according to the first embodiment. FIG. FIG. 6 is a cross-sectional view showing a modification of the semiconductor device according to the first embodiment. FIG. 6 is a cross-sectional view showing a modification of the semiconductor device according to the first embodiment. FIG. 6 is a cross-sectional view showing a semiconductor device according to a second embodiment. FIG. 10 is a cross-sectional view for illustrating the method for manufacturing the semiconductor device according to the second embodiment. FIG. 6 is a perspective view showing an outer shape of a semiconductor device according to a third embodiment. It is sectional drawing in III-III of FIG. FIG. 10 is a cross-sectional view for illustrating the method for manufacturing the semiconductor device according to the third embodiment.

Explanation of symbols

16 IGBT (semiconductor element)
24 External electrode 30 Housing 34 Through-hole 42 Molding die 44 Cavity 46 Convex part 48 Concave part

Claims (6)

A semiconductor element;
An external electrode electrically connected to the semiconductor element;
A thermoplastic resin housing that seals the semiconductor element so that a part of the external electrode is led out,
The external electrode is provided with a through hole at the root of the portion derived from the housing,
At least a part of the through hole is filled with the thermoplastic resin constituting the housing.   2. The semiconductor device according to claim 1, wherein the casing is provided with a convex portion that covers a periphery of the through hole of the external electrode and that narrows from the inside to the outside of the casing. .   3. The semiconductor device according to claim 2, wherein a region including the convex portion in the vicinity of a portion where the external electrode is led out of the housing is depressed toward the inside of the housing. Electrically connecting an external electrode provided with a through hole to a semiconductor element;
A step of leading a part of the external electrode out of the cavity in a state where the semiconductor element is placed in a cavity of a molding die, and injecting a thermoplastic resin into the cavity to seal the semiconductor element. ,
When sealing the semiconductor element, the through hole is disposed at an outer edge of the cavity, and at least a part of the through hole is filled with the thermoplastic resin.   The semiconductor device according to claim 4, wherein the molding die is provided with a recess that narrows from the inside to the outside of the cavity around the through hole of the external electrode. Method.   6. The method of manufacturing a semiconductor device according to claim 5, wherein the molding die protrudes toward the inside of the cavity in a region including the concave portion in the vicinity of a portion from which the external electrode is led out. .

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