JPH0312468B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a semiconductor device, and in particular, an electrode plate having minute portions of the same shape is fixed to an electrode film on the surface of a semiconductor substrate with soft wax, and the semiconductor element substrate and the electrode plate are bonded with an organic resin. The present invention relates to a semiconductor device having a coated structure. [Background of the Invention] The present invention relates to a gate turn-off thyristor (hereinafter referred to as
As the electrode structure of power semiconductor devices such as GTO (abbreviated as GTO) and transistors, metal foil having approximately the same shape as the fine control electrode film and main electrode film provided on the main surface is coated with solder or other soft material. We propose a structure fixed with wax. With a structure like this,
Compared to conventional semiconductor devices in which aluminum wires used as electrode lead wires were wire-bonded using ultrasonic methods, or semiconductor devices in which copper leads with headers were connected by soldering, bonding pads can be eliminated. This has the advantage that the semiconductor device can be made smaller. The inventor has an electrode structure as described above.
The GTO was incorporated into an inverter device and tested for operation, as well as thermal cycle tests and power cycle tests to confirm reliability. the result,
When coating GTO with organic resin for surface protection and electrical insulation, the following problems were found in thermal cycle tests and power cycle tests. FIG. 1a is a perspective view of the electrode structure of a GTO thyristor having the above structure, and FIG. 1b is a sectional view of the GTO thyristor. In the figure, there is a GTO thyristor 100, and this GTO thyristor 100
The cathode electrode 102 is one of the main electrodes that is ohmic-connected to the n-emitter 101, the cathode copper foil 103 is bonded to the cathode electrode 102 with solder 116, and the p-base 104 is exposed on the same surface as the n-emitter 101. It consists of an auxiliary gate electrode 105 and a main gate electrode 106 which are ohmic-connected control electrodes, and a main gate electrode copper foil 107 which is bonded and fixed to the main gate electrode 106 with solder 116. The cathode electrode copper foil 103 includes a cathode microelectrode connection portion 108, a cathode electrode bridge portion 109,
It consists of a cathode electrode common part 110, and the cathode electrode common part 110 is joined and fixed to a cathode electrode copper plate 111 with solder. Similarly, the main gate electrode copper foil 107
2 gate electrode bridge section 113, gate electrode common section 1
14, and this gate electrode common part 114 is
It is bonded and fixed to the gate electrode copper plate 115 by solder. The anode electrode 196, which is the other main electrode of the GTO thyristor 100, is bonded and fixed to the electrode plate 117 with solder. The entire GTO thyristor 100, main gate electrode copper foil 107, cathode electrode copper foil 103, gate electrode copper plate 115, cathode electrode copper plate 111, and electrode plate 117 is covered with an organic resin 118. As a result of a thermal cycle test and a power cycle test of a semiconductor device having such a structure, the gate electrode bridge portion 113 of the main gate electrode copper foil 107 or the cathode electrode bridge portion 109 of the cathode electrode copper foil 103 suffered thermal fatigue and stress. It was found that the signal was cut off from areas of high concentration. In power cycle tests, some GTO thyristors were destroyed due to heat caused by current concentration. [Object of the Invention] An object of the present invention, which has been made in view of the above circumstances, is to provide a semiconductor device that is resistant to thermal fatigue. [Summary of the invention] In order to achieve such an object, the present invention has the following features:
A metal plate, a semiconductor pellet placed on the metal plate by soldering and having a plurality of strip-shaped electrodes arranged in parallel on the upper surface in a direction perpendicular to the longitudinal direction of the semiconductor pellet; The first plate is placed on the plate by soldering through an insulator.
and a second external lead-out electrode, which are connected to the entire surface of each electrode by soldering every other one or more of the electrodes of the semiconductor pellet, and have a common base via an electrode bridge, and this base is connected to the first and second external lead electrodes. A first internal lead made of comb-shaped metal foil is soldered to an external extraction electrode, and a first internal lead is soldered to the entire surface of an electrode other than the electrode connected to the first internal lead and is connected via an electrode bridge portion. a second inner lead made of a comb-shaped metal foil having a common base and the base being soldered to the second external extraction electrode;
A semiconductor device comprising: a gel-like organic resin disposed to cover the surface of the semiconductor pellet containing each of the electrodes, and the electrode bridge portion and base of each of the internal leads. With this configuration, according to the present invention, the above object is achieved through the following actions. First, the external lead-out electrodes are not directly connected to the semiconductor pellet, but are fixed on the same metal plate at intervals, which prevents the semiconductor pellet from being destroyed by thermal expansion of the external lead-out electrodes. can. On the other hand, since the structure is such that the external lead electrode and the electrode of the semiconductor pellet are connected by an internal lead made of metal foil, the difference in thermal expansion between the semiconductor pellet and the external lead electrode placed on the same metal plate causes Any changes in their relative positions that occur are absorbed by the internal leads. However, since the internal lead is formed from a plurality of electrode parts and a base part at the electrode bridge part, and is also formed from metal foil with a certain thickness, repeated stress (bending stress) due to heat cycles is generated. If this happens, there is a risk of it breaking due to fatigue. In particular, stress tends to concentrate at the electrode bridge portion. Therefore, in the present invention, the entire internal lead including the upper surface of the semiconductor pellet and the external lead-out electrode is covered with a gel-like organic resin. In other words, the flexibility of the gel-like organic resin allows the bending of the internal lead, including the electrode bridge, to be dispersed throughout the entire lead, thereby preventing stress from concentrating on specific areas such as the electrode bridge, or reducing stress. This made it resistant to thermal fatigue. [Embodiment of the Invention] FIG. 2 is a cross-sectional configuration diagram showing an embodiment of a semiconductor device according to the present invention. In the same figure, the GTO thyristor 100 (its dimensions are, for example, 8.0 mm□) is made of Ni
Plated copper electrode plate 201 (its dimensions are, for example, 25
×29 × 2 ^t ) and solder 2101 with a composition of 40% Pb and 60% Sn. The copper electrode plate 201 is a tungsten and nickel metallized layer of an alumina insulating plate 202 (its dimensions are, for example, (28 × 32 × 0.4 ^t )) and solder. 210
2, and the alumina insulating plate 202 is attached to a Ni-plated copper heat sink plate 203 (its dimensions are, for example,
63 x 36 x 3.2 ^t ) and are bonded with solder 2103. The copper electrode plate 201 has metallized layers of an alumina insulating plate 204 for the cathode terminal (its dimensions are, for example, 22 x 6 x 2 ^t ) and an alumina insulating plate 205 for the gate terminal (its dimensions are, for example, 22 x 6 x 2 ^t ). An anode copper electrode terminal 207 is bonded with solders 2104 and 2105, and an anode copper electrode terminal 207. The alumina insulating plate 204 for the cathode terminal connects to the L-shaped cathode electrode terminal 111, and the alumina insulating plate 205 for the gate terminal connects to the gate copper electrode terminal 115, which also serves as an L-shaped external extraction electrode, with solder 210, respectively.
6 and 2107, and the cathode electrode copper foil 103 (its thickness is e.g.
A cathode electrode terminal 111 (35 μm ^t ) is used as an external lead electrode, and a gate electrode copper foil 107 (its dimension is, for example, 35 μm ^t ) is soldered to the gate electrode terminal 115 as an internal lead. A resin case 206 (its height is, for example, 12 mm) is attached to a silicone adhesive image 211 on the copper heat sink plate 203.
It is glued with. Inside the resin case 206, an organic resin (208) is placed on the cathode electrode copper foil 1.
03 and the gate electrode copper foil 107 about 1 inch above it.
The organic resin (209) is injected to completely cover the resin case 209 and cured by heating.
It is injected to the position of the upper opening of No. 06 and hardened by heating. In the semiconductor device configured in this way,
Table 1 shows the organic resin () and the materials used as the organic resin ().

【table】

[Table] In addition, a current is generated between the gate electrode terminal 115 and the cathode electrode terminal 111 of the GTO thyristor 100.
Flowing 10A, N emitter 101 and P base 104
Measure the forward voltage drop of the junction between -55℃ (20 minutes)
→ 20℃ (10 minutes) → 150℃ (20 minutes) → 20℃ (10 minutes)
Changes were tracked by a thermal cycle test in which one cycle was . FIG. 3 shows forward resistance traces from a thermal cycle test with a test GTO thyristor device. Test GTO thyristor device
KJR9033 silicone resin to the above organic resin (),
Sample and test in which organic resin () is coated with KE523-16Fr-5 two-component epoxy resin.
GTO thyristor device is made of organic resin ()
KE104 silicone gel, KE523 to organic resin ()
This is a sample coated and molded with -16Fr-5.
If a soft resin with high penetration is used as the organic resin () like KE104, the forward resistance will not change, but in KJR9033, the forward resistance will change due to partial thermal fatigue damage at the gate electrode bridge and cathode electrode bridge. It can be seen that the resistance increases. Furthermore, Table 2
The types of resin applied and molded and the results of thermal cycle tests are shown.

【table】

〔Effect of the invention〕

As is clear from the above description, the semiconductor device according to the present invention is extremely resistant to thermal fatigue.

[Brief explanation of the drawing]

FIGS. 1a and 1b are a perspective view showing an example of a conventional semiconductor device, a cross-sectional view of a pellet, and a second
Figures a and b are a cross-sectional view and a partially enlarged view showing one embodiment of the semiconductor device according to the present invention, respectively, Figure 3 is a graph showing the effects of the present invention, and Figure 4 is another example of the semiconductor device according to the present invention. It is a sectional view showing an example. 100...GTO, 103...Cathode electrode copper foil, 107...Main gate electrode copper foil, 201...Copper electrode plate, 202...Alumina insulating plate, 203...
Copper heat sink plate, 206...Resin case, 2
08...Organic resin (), 209...Organic resin ().

Claims (1)

[Claims] 1. A metal plate, a semiconductor pellet placed on the metal plate by soldering and having a plurality of strip-shaped electrodes arranged in parallel on the upper surface in a direction perpendicular to the longitudinal direction of the semiconductor pellet, and a semiconductor pellet with respect to the semiconductor pellet. first and second external lead-out electrodes are respectively placed on the metal plate at intervals by soldering via an insulator; a first internal lead made of comb-shaped metal foil that is connected by soldering and has a common base via an electrode bridge portion, and this base is connected to the first external extraction electrode by soldering; and the first internal lead. A comb-shaped metal foil that is soldered to the entire surface of the electrode other than the electrode connected to the electrode, and has a common base via an electrode bridge, and this base is soldered to the second external extraction electrode. a second internal lead, a gel-like organic resin disposed to cover the semiconductor pellet surface including each of the electrodes, and the electrode bridge portion and base of each of the internal leads. Device. 2. The semiconductor device according to claim 1, wherein the gel-like organic resin is a material having a penetration degree of 40 or more.