JP2865196B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a semiconductor device whose electrical characteristics do not deteriorate even in an environment where repeated thermal shocks are applied.

[0002]

2. Description of the Related Art As shown in, for example, Japanese Utility Model Publication No. 5-19957, a support electrode formed of metal and having a concave portion, a lead electrode, and a fixed portion between a bottom portion of the concave portion of the support electrode and the lead electrode. An output rectifier diode of an automotive alternator including a semiconductor chip provided and a protective resin filled in the recess and covering the semiconductor chip is known. In this output rectifier diode, as shown in FIG.
A diode chip (semiconductor chip) 1 is fixed between the dish-shaped support electrode 2 and the header 3a of the lead electrode 3, and the header of the diode chip 1 and the lead electrode 3 is protected by the protective resin 4 filled in the support electrode 2. The 3a side is sealed.
The support electrode 2 is made of a metal plate obtained by plating a metal mainly composed of copper with nickel, and is formed in a dish-shaped concave portion 2.
a, and also serves as a heat sink of the diode chip 1. The lead electrode 3 is made of a nickel-plated rod-shaped copper lead member, and has a flange-shaped header portion 3.
a and a lead portion 3b extending substantially perpendicularly from the header portion 3a
And a bend portion 3c formed in a U-shape in the lead portion 3b.
And The diode chip 1 is fixed to the bottom 2b of the recess 2a of the support electrode 2 and the header 3a of the lead electrode 3 by solders 5 and 6, respectively. The header portion 3a side of the diode chip 1 and the lead electrode 3 is covered with a protective resin 4 made of silicone resin filled in the concave portion 2a of the support electrode 2, and harmful substances such as moisture or ionic impurities are contained in the diode chip 1. It prevents entry into the side surface 1a.

[0003]

In the output rectifier diode shown in FIG. 3, the support electrode 2 made of copper has a linear expansion coefficient of 16.8 × 10 ^-6 / ° C., and the protective resin 4 made of silicone resin has The coefficient of linear expansion is 6.0 to 8.0 × 10 ^-6 /
Since the temperature is in ° C., the linear expansion coefficients of the two members are greatly different. Therefore, when used in a severe environment where a heat cycle is repeatedly applied, an excessive thermal stress is generated in the protective resin 4 due to a difference in linear expansion coefficient between the support electrode 2 and the protective resin 4,
The protective resin 4 may peel off from the support electrode 2 in some cases. In particular, since the silicone resin forming the protective resin 4 has an extremely large shrinkage during the thermosetting process, stress concentrates on the bonding portion indicated by arrows A and B, and the protective resin 4 is formed on the lead portion 3b of the lead electrode 3. Adhesive surface or recess 2a of support electrode 2
Is easily peeled off from the adhesive surface. Therefore, when the output rectifier diode shown in FIG. 3 is used in a severe environment where a thermal shock is repeatedly applied many times, the bonding surface or support of the lead portion 3b and the header portion 3a of the lead electrode 3 starting from the bonding portions A and B is used. The peeling of the protective resin 4 progresses along the bonding surface of the concave portion 2a of the electrode 2, and finally the diode chip 1
The peeling of the protective resin 4 may reach the side surface 1a. In the state where the peeling of the protective resin 4 has progressed in this manner,
A harmful substance such as moisture or ionic impurities penetrates the side surface 1a of the diode chip 1 from the peeled interface, thereby causing poor insulation and an increase in reverse current, thereby deteriorating the electrical characteristics of the semiconductor device.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor device whose electrical characteristics do not deteriorate even when used in a severe environment where thermal shock is repeatedly applied many times.

[0005]

A semiconductor device according to the present invention is formed of a metal containing copper as a main component and has a recess (2).
a support electrode (2) having a), a lead electrode (3),
A semiconductor chip (1) fixed between the bottom (2b) of the recess (2a) of the support electrode (2) and the lead electrode (3);
A protection resin (7) filled in the recess (2a) and covering the semiconductor chip (1). Protection resin (7)
Is an epoxy resin having a linear expansion coefficient of 15.0 to 19.0 × 10 ⁻⁶ / ° C., and the supporting electrode (2) has a linear expansion coefficient of 1
5.0-17.0 × 10 ⁻⁶ / ° C., an annular groove (8) is formed on the inner peripheral surface of the side wall (2c) constituting the recess (2a) of the support electrode (2), and the annular groove is formed. (8) is filled with a protective resin (7). The width of the annular groove (8) is
It has an ant-shaped cross section that extends towards a). In another embodiment according to the present invention, a protrusion (9) is formed on the bottom (2b) of the recess (2a) of the support electrode (2), and the periphery of the protrusion (9) is filled with a protective resin (7). The projection (9) is formed in a ring shape inclining toward the side wall (2c) of the recess (2a) of the support electrode (2).

[0006] The difference in linear expansion coefficient between the support electrode (2) and the protective resin (7) is reduced to make the linear expansion coefficient uniform, and the side wall (2c) constituting the recess (2a) of the support electrode (2). By forming the annular groove (8) on the inner peripheral surface of the support electrode (2), the annular groove (8) is filled with the protective resin (7), and the side wall (2c) of the support electrode (2) and the protective resin (7) are formed. Becomes stronger, and the adhesion between the concave portion (2a) of the support electrode (2) and the protective resin (7) can be improved. Also, even if the heat cycle is repeatedly applied, the protective resin (7) does not generate excessive thermal stress. Therefore, the protective resin (7) can be used even in a severe environment where a thermal shock is repeatedly applied many times. Can be suppressed from the support electrode (2), harmful substances such as moisture or ionic impurities can be suppressed from entering the inside, and deterioration of electrical characteristics of the semiconductor device can be prevented. The protective resin (7) is provided at the bottom (2) of the concave portion (2a) of the support electrode (2).
b) is securely locked to the projection (9) formed to be inclined,
Peeling from the support electrode (2) is prevented. When the linear expansion coefficient of the support electrode (2) is larger than that of the protective resin (7),
During the thermal expansion of the support electrode (2), the support electrode (2) expands radially outward. At this time, if the protrusion (9) is inclined toward the side wall (2c) of the recess (2a), the protrusion (9) is formed on the bottom surface of the recess (2a) by the protective resin (7).
, And the adhesion between the protective resin (7) and the support electrode (2) can be enhanced. If the annular groove (8) is formed to have a dovetail cross section, the inclined surface of the groove (8) exerts a pressing effect of the protective resin (7) as in the case of the projection (9).

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a semiconductor device according to the present invention applied to an output rectifier diode of an automotive alternator will be described below with reference to FIGS. 1 and 2. FIG. 1 and 2
In FIG. 3, substantially the same parts as those in FIG.
The description is omitted. As shown in FIG. 1, the output rectifier diode of the present embodiment has a coefficient of linear expansion of copper support electrode 2 of 16.1 instead of protective resin 4 made of silicone resin used in the conventional output rectifier diode shown in FIG. 8x1
Coefficient of linear expansion extremely close to 0 ^-6 / ° C.
The header portion 3a of the diode chip 1 and the lead electrode 3 by the protective resin 7 made of an epoxy resin having a temperature of 0 ^-6 / ° C.
Seal the side. The epoxy resin constituting the protective resin 7 is
It has heat resistance close to that of silicone resin, has extremely small curing shrinkage than silicone resin, and is inexpensive. In the embodiment shown in FIG. 1, an annular groove 8 having a dovetail cross section that widens toward the bottom 8 a is formed along the inner peripheral surface of the side wall 2 c constituting the recess 2 a of the support electrode 2. The annular groove 8 is formed, for example, by pressing into a dovetail section integrally with the concave portion 2a of the support electrode 2 or by cutting the inner peripheral surface of the side wall 2c of the support electrode 2 with a lathe. In the case of forming by press working, once the annular groove is formed by the first press working, then the second press working is performed,
It can be formed in a dovetail section. Other configurations are substantially the same as those of the conventional output rectifier diode shown in FIG.

In this embodiment, the linear expansion coefficient of the copper supporting electrode 2 as the protective resin 7 for sealing the diode chip 1 and the lead electrode 3 on the header portion 3a side is 16.8 × 10 ^-6 /
Linear expansion coefficient 15.0 to 19.0 × 10 substantially equal to ° C.
An epoxy resin having ^-6 / ° C is used. For this reason, the difference in linear expansion coefficient between the support electrode 2 and the protective resin 7 is reduced or equalized, and no excessive thermal stress occurs in the protective resin 7 at high temperatures. Therefore, the protective resin 7 does not peel off from the support electrode 2 even when used in a severe environment where a heat cycle is repeatedly applied. Therefore, even when used in harsh environments,
Since it is possible to prevent harmful substances such as moisture and ionic impurities from entering the side surface 1a of the diode chip 1, it is possible to prevent deterioration of electrical characteristics of the output rectifier diode such as poor insulation and increase in reverse current. It becomes possible. In the embodiment shown in FIG. 1, the annular groove 8 having a dovetail cross section is formed along the inner peripheral surface of the side wall 2 c of the concave portion 2 a of the support electrode 2. 8, the side wall 2c of the support electrode 2 and the protective resin 7
And the adhesion between the protective resin 7 and the concave portion 2a of the support electrode 2 can be improved. In particular, even when the support electrode 2 expands outward in the radial direction,
Since the inclined surface of the groove 8 acts to press the protective resin 7 against the bottom 2b of the concave portion 2a, there is an advantage that the adhesion between the protective resin 7 and the support electrode 2 can be maintained at a high level. Also,
The creeping distance along the surface of the concave portion 2a from the bonding portion B to the diode chip 1 is increased, so that intrusion of harmful substances can be prevented.

FIG. 2 shows another embodiment of the present invention in which a projection 9 is formed on the bottom 2b of the concave portion 2a of the support electrode 2 in an annular shape and is inclined toward the side wall 2c of the concave portion 2a. That is, the protrusion 9 is inclined upward in a direction in which the diameter increases. The protective resin 7 is securely locked by the projection 9 formed on the bottom 2b of the concave portion 2a of the support electrode 2 so as to be inclined.
Is prevented from being peeled off. In particular, when the linear expansion coefficient of the support electrode 2 is larger than that of the protective resin 7, the support electrode 2 expands radially outward.
Since the protective resin 7 acts to press the bottom 2b of the concave portion 2a similarly to the inclined surface of the groove 8, there is an advantage that the adhesion between the protective resin 7 and the support electrode 2 can be secured at a high level. To form the projection 9, when the support electrode 2 is stamped and formed by press molding, first, an annular projection projecting at right angles from the bottom 2b is formed, and then a conical press die is pressed against the annular projection. At a predetermined angle as shown in FIG.

[0010] The present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above-described embodiment, the annular groove 8 having a dovetail cross section is formed along the inner peripheral surface of the side wall 2c of the recess 2a of the support electrode 2, but the adhesion between the recess 2a of the support electrode 2 and the protective resin 7 is formed. Is sufficiently strong, the annular groove 8 may be omitted or a groove having a right-angled cross section may be used. Further, the grooves 8 and the projections 9 may be formed intermittently.
An annular groove is formed in the outer surface of the lead portion 3b or in the header portion 3a in the lead portion 3b below the bonding portion A to increase the adhesion between the protective resin 7 and the lead portion 3b or the header portion 3a. The creeping distance from to the diode chip 1 may be increased. The linear expansion coefficient of the support electrode is 15.
It can be changed appropriately within the range of 0 to 17.0 × 10 ⁻⁶ / ° C. Further, the present invention can be applied to other semiconductor devices such as a transistor or a thyristor other than the output rectifier diode of the automotive alternator.

[0011]

According to the semiconductor device of the present invention, even if the semiconductor device is used in a severe environment where a thermal shock is repeatedly applied many times, separation of the protective resin from the electrode is prevented, and harmful substances such as moisture and ionic impurities are prevented. Can be suppressed, so that a highly reliable semiconductor device with very little characteristic deterioration can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a semiconductor device according to the present invention applied to an output rectifier diode of an automotive alternator.

FIG. 2 is a cross-sectional view showing another embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an output rectifier diode of a conventional automotive alternator.

[Explanation of Codes] . . Diode chip (semiconductor chip), 1
a. . . Aspect, 2. . . Support electrode, 2a. . . Recess, 2b. . . Bottom, 2c. . . Side wall,
3. . . Lead electrode, 3a. . . Header part, 3
b. . . Lead part, 5,6. . . 6. solder; . . 7. protective resin; . . 8. an annular groove; . . Protrusions,

Claims (4)

(57) [Claims] A support electrode formed of a metal containing copper as a main component and having a recess; a lead electrode; a semiconductor chip fixed between the bottom of the recess of the support electrode and the lead electrode; A protective resin filled in the recess and covering the semiconductor chip, wherein the protective resin has a linear expansion coefficient of 15.0 to 19.0 × 10 ⁻⁶ /
The support electrode has a linear expansion coefficient of 15.0 to 17.0 × 10 ⁻⁶ / ° C., and an annular groove is formed on an inner peripheral surface of a side wall constituting a concave portion of the support electrode. A semiconductor device, wherein the protection resin is filled in the annular groove. 2. The semiconductor device according to claim 1, wherein the width of the annular groove has a dovetail cross section that extends toward the bottom. 3. A support electrode formed of a metal containing copper as a main component and having a recess, a lead electrode, a semiconductor chip fixed between the bottom of the recess of the support electrode and the lead electrode, A protective resin filled in the recess and covering the semiconductor chip, wherein the protective resin has a linear expansion coefficient of 15.0 to 19.0 × 10 ⁻⁶ /
The support electrode has a linear expansion coefficient of 15.0 to 17.0 × 10 ⁻⁶ / ° C., and a protrusion is formed at the bottom of the concave portion of the support electrode. A semiconductor device filled with the protective resin. 4. The semiconductor device according to claim 3, wherein said projection is formed in an annular shape inclining toward a side wall portion of the concave portion of said support electrode.