JPH0452999Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a semiconductor device, and particularly to a semiconductor device that can sufficiently prevent harmful substances that adversely affect electrical characteristics from entering the inside of the device.

2. Description of the Related Art For example, a resin-sealed diode in which a semiconductor chip is sealed with a soft resin, that is, a rubber-like resin, is known as an element for rectifying the output of an alternator used in an automobile. This resin-sealed diode will be explained with reference to FIG.

The diode 1 includes a bowl-shaped support electrode 2 that has a flat base portion 2a and a side portion 2b that bends and extends from the base portion 2a and has a concave portion 2c, a flange-shaped header 3a, and a side portion 2b that is smaller than the header 3a. A lead electrode 3 consisting of a lead portion 3b having a cross section, a semiconductor chip 4 connected between the base portion 2a and the header 3a, and a soft resin body 5 filling the recess 2c and sealing the semiconductor chip 4. It is equipped with The upper surface 4a and lower surface 4b of the semiconductor chip 4 are bonded to the lower surface _3a1 of the header 3a and the upper surface _2a1 of the base portion 2a by solder 6, respectively.

The base portion 2a of the bowl-shaped support electrode 2 has a thickness of about 1 mm. In addition, the side portion 2b that bends and extends from the base portion 2a has a diameter of approximately 9.5 mm and a height of approximately 2.3 mm.
It is annular with a thickness of about 0.5 mm. The header 3a of the lead electrode 3 has a diameter of about 5 mm and a thickness of about 0.5 mm. The lead portion 3b extending upward from the header 3a has a diameter of about 1.5 mm and a length of about 18 mm. A U-shaped bend portion _3b1 is formed in the lead portion 3b. However, the lead portion 3b may be formed linearly without providing the U-shaped bend portion _3b1 .

Nickel electrodes (not shown) are formed on both main surfaces 4a and 4b of the semiconductor chip 4. solder 6
is Pb with 95% lead (Pb) and 5% tin (Sn) by weight.
-It is a Sn-based alloy. The bowl-shaped support electrode 2 and lead electrode 3 are made of copper coated with nickel.
The soft resin body 5 is silicon rubber. The soft resin body 5 is formed so as to rise slightly from the recess 2c of the bowl-shaped support electrode 2, and covers the side surface 4c of the semiconductor chip 4, the lower part of the lead part 3b following the header 3a, and the recess 2c side of the bowl-shaped support electrode 2. Cover.
The soft resin body 5 is made by fixing the semiconductor chip 4 and the lead electrode 3 to the bowl-shaped support electrode 2, and then pouring a resin-forming slime into the recess 2c of the bowl-shaped support electrode 2.
It is formed through heat treatment.

Problems to be Solved by the Invention Incidentally, the bond between the soft resin body 5 and the supporting electrode 2 and the lead electrode 3 is likely to be broken by the presence of acid or alkali. Moreover, in the heat treatment process for solidifying the soft resin body 5, the soft resin body 5 shrinks, and stress is concentrated on the bonded portions indicated by arrows A and B. Therefore, the soft resin body 5 at the bonded parts A and B becomes easily peeled off from the surface of the lead part 3b of the lead electrode 3 or the upper part _2b2 of the bowl-shaped support electrode 2. Therefore, if the diode 1 is used for a long period of time in a harsh environment, the soft resin material will form along the surface of the lead part 3b of the lead electrode 3 or the side part 2b of the bowl-shaped support electrode 2 starting from the adhesive parts A and B. The peeling of 5 progresses, and eventually the upper surface 3 of the header 3a
a ₂ and side 3a ₃ or side 2b of bowl-shaped supporting electrode 2
through the inner surface 2b ₁ and the upper surface 2a ₁ of the base part 2a,
The peeling of the soft resin body 5 may reach the side surface 4c of the semiconductor chip 4. In this state where the peeling has progressed, the diode 1 is separated from the soft resin body 5.
Harmful substances such as moisture and ionic impurities that enter the side surface 4c of the semiconductor chip 4 from the peeled portion of the semiconductor chip 4 cause an increase in reverse current, resulting in poor characteristics such as shot-like appearance.

On the other hand, sealing with a hard resin such as epoxy resin (non-rubber-like or non-gel-like resin) has the possibility of solving the above problem because the adhesion and bonding of the hard resin to metal is relatively strong. There is. However, since the diode 1 in which the soft resin body 5 is replaced with an epoxy resin is used by being attached to a heat sink by soldering, the sealing effect of the epoxy resin is impaired due to the heat history during this soldering and other times. Put it away. That is, thermal stress based on the difference in thermal expansion coefficient between the epoxy resin and the supporting electrode 2 causes peeling at the interface between the epoxy resin and the supporting electrode 2, resulting in deterioration of characteristics due to intrusion of harmful substances.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a semiconductor device that has a high ability to prevent harmful substances that adversely affect electrical characteristics from entering the semiconductor device.

Means for Solving the Problems A semiconductor device according to the present invention includes a support electrode having a recess, a lead electrode, and a semiconductor chip connected between the bottom of the recess of the support electrode and the lead electrode.
and a soft resin body filling the recess and covering the semiconductor chip. A fibrous layer of approximately constant thickness made of woven or nonwoven fabric, impregnated with hard resin, and solidified is fixed to the upper part of the soft resin body. A central hole into which a lead electrode is inserted is formed approximately at the center of the fiber layer. A portion of the fiber layer adjacent to the center hole is bonded to the lead electrode by a hard resin fixed to the fiber layer. The outer periphery of the fiber layer is adhered to the side of the support electrode by a hard resin fixed to the fiber layer.

Function Since the fibrous layer is thinly formed using a fibrous material in which cellulose is intertwined as a core material, the difference in expansion coefficient between the hard resin and the metal is alleviated, and large thermal deformation does not occur in the fibrous layer. Therefore, the fiber layer does not peel off from the support electrode or lead electrode due to thermal history during soldering or the like. Moreover, the soft resin body is reinforced by the fiber layer, and high mechanical strength can be obtained. For this reason,
When a semiconductor device is used in a harsh environment, peeling of the resin along the surface of the support electrode or lead electrode becomes difficult to progress at the fiber layer, and this prevents harmful substances from reaching the surface of the semiconductor chip. strengthened.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6. In these drawings, the same parts as those shown in FIG. 7 are designated by the same reference numerals, and their explanation will be omitted.

As shown in FIG. 1, in the semiconductor device of the present invention, the fiber layer 8 is fixed to the upper part of the soft resin body 7 within the recess 2c of the support electrode 2. As shown in FIG. The soft resin body 7 is made of silicone rubber, and the fiber layer 8 is a hard film in which a fiber material such as glass fiber constituting a woven or nonwoven fabric is impregnated with a hard resin and solidified. The fiber layer 8 has a central hole 8a and is formed in a circular shape. The lead portion 3b of the lead electrode 3 is inserted through the center hole 8a. The fiber layer 8 is bonded to the lead portion 3b of the lead electrode 3 at a portion adjacent to the center hole 8a, and is bonded to the inner surface 2b1 of the side portion 2b of the support electrode 2 at the outer peripheral portion 8b of the fiber layer ₈ .

Next, a method of manufacturing the diode shown in FIG. 1 will be explained.

First, a bowl-shaped support electrode 2, a semiconductor chip 4, and a lead electrode 3 are bonded together with solder 6 as shown in the figure to form an unsealed diode. Next, after etching, cleaning and drying the side surface 4c of the semiconductor chip 4, a resin-forming slime of silicone rubber is injected into the recess 2c of the bowl-shaped support electrode 2, and this slime is thermally hardened by heating. . The silicone rubber becomes a soft resin body 7 as a protective resin and sealing resin that covers the side surface 4c of the semiconductor chip 4. Next, the fiber material 9 shown in FIG. 6a is prepared. The fiber material 9 is
A nonwoven fabric made of glass fibers intertwined with cellulose is impregnated with a slime for forming an epoxy resin, and is solidified in an uncured state. Glass fiber woven fabric may be used instead of non-woven fabric. The fiber material 9 has a central hole 9a and a cut portion 9b. Thereafter, the center hole 9a of the fiber material 9 is inserted into the lead portion 3b of the lead electrode 3.
and heat treated. Through this heat treatment, the epoxy resin impregnated into the fiber material 9 is once dissolved in the soft resin body 7 and then thermally cured to form the fiber layer 8. By using the fiber material 9 whose core material is a fiber material in which cellulose is entangled, a fiber layer 8 without pinholes can be obtained. Furthermore, the thickness of the fiber layer 8 can be controlled better than the method of applying a resin-forming mucilage. Finally, a resin-forming slime of silicone rubber is injected onto the fiber layer 8 to form a soft resin body 10.

In order to investigate the environmental resistance performance of the semiconductor device according to the present invention, an electrolytic test, which is a severe accelerated life test for examining the environmental resistance performance, was conducted using the diode according to the present invention and a conventional diode as samples. That is, each diode was immersed in 10% salt water at room temperature for 10 seconds with a reverse voltage of 7.5 applied. After 10 seconds, each diode was removed from the salt water and left in the air at room temperature for 30 minutes while a reverse voltage was applied. This process was carried out in units of 10 cycles up to 50 cycles, with these processes as one cycle. After each 10 cycles, each diode was cleaned and dried and the reverse current was measured. In this measurement, each diode was selected as a good product if the reverse current was within the standard value, and as a defective product if it was outside the standard value. As a result, the diode according to the present invention showed good results.

In this electrolytic test, hydrochloric acid (HCl) is generated by electrolysis of salt water at the (+) pole of the bowl-shaped support electrode 2 and lead electrode 3, and the same is generated at the (-) pole. Caustic soda (NaOH) is generated. Electrolytes containing these acids or alkalis are
This breaks the bond between the electrode and the sealing resin, causing the sealing resin to separate from the electrode. The electrolytic solution penetrates into the part where the peeling has occurred, causing further peeling, and by repeating this process, the peeling of the sealing resin body progresses. Therefore, in this electrolytic test, the strength of the bond between the sealing resin body (soft resin bodies 5, 7, 10 and fiber layer 8) and the support electrode 2 and lead electrode 3 is clearly reflected in the defective rate. This is a test. In addition, throughout this test, there was no problem of peeling between the silicone rubber (soft resin bodies 7 and 10) and the epoxy resin (fiber layer 8). This is because the expansion coefficient difference between the hard resin and the metal is alleviated by the fiber layer 8, and the soft resin bodies 7 and 10 are reinforced and the soft resin bodies 7 and 10 are
This is because the mechanical strength of the steel increases.

In the present invention, various modifications of the fiber layer 8 are possible as illustrated in FIGS. 2 to 5. Figure 2 shows
An example is shown in which a fiber layer 8 is adhered to the upper surface _3a2 of the header 3a. FIG. 3 shows an example in which no soft resin body is formed on the fiber layer 8. In this example, in order to ensure a large adhesion area between the fiber layer 8 and the support electrode 2, the upper surface _2b2 of the side portion 2b is formed into a flange shape. 4 and 5 show an example in which a notch 8c is provided in the fiber layer 8, which is a modification of the example shown in FIGS. 1 and 3. FIG. 6b shows a fiber layer 8 having a notch 8c.
A fiber material 9 having a notch 9c to form a
shows. By providing the cutout portion 8c, peeling of the fiber layer 8 from the support electrode 2 or the lead electrode 3 due to thermal history can be more completely prevented. Further, the notch portion 8c may be formed in the example shown in FIG.

In the above embodiment, instead of the glass fiber used as the core fiber material of the fiber layer 8, other non-conductive inorganic fiber material or organic fiber material can be used. Furthermore, as the synthetic resin impregnated into the fiber material, other hard resins such as polyimide resins may be used instead of epoxy resins.

Effects of the Invention As described above, in the semiconductor device according to the present invention, separation between the sealing resin body and the electrode is difficult to progress, and the ability to prevent the intrusion of harmful substances is enhanced. Therefore, according to the present invention, a highly reliable semiconductor device with improved environmental resistance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a semiconductor device according to the present invention, FIGS. 2, 3, 4 and 5 are sectional views of a semiconductor device showing modifications of the present invention, and FIG. 6 is a sectional view of a semiconductor device in which a fiber layer is formed. FIG. 7 shows a cross-sectional view of a conventional semiconductor device. 2... Support electrode, 2a... Base part, 2b...
Side part, 2c... recess, 3... lead electrode, 3a...
... Header, 3b ... Lead part, 4 ... Semiconductor chip, 6 ... Solder, 7, 10 ... Soft resin body, 8
...Fiber layer, 8a...Central hole, 8b...Outer periphery,
9...Fiber material.

Claims (1)

[Claims for Utility Model Registration] (1) A support electrode having a recess, a lead electrode, a semiconductor chip connected between the bottom of the recess of the support electrode and the lead electrode, and a semiconductor chip filled in the recess. and a soft resin body covering the semiconductor chip, wherein a fibrous layer of a substantially constant thickness made of woven or nonwoven fabric, impregnated with hard resin, and solidified is fixed to the upper part of the soft resin body. A center hole into which the lead electrode is inserted is formed approximately at the center of the fiber layer, and a portion of the fiber layer adjacent to the center hole is bonded to the lead electrode by the hard resin fixed to the fiber layer. . A semiconductor device, wherein an outer peripheral portion of the fiber layer is adhered to a side portion of the support electrode by the hard resin fixed to the fiber layer. (2) The semiconductor device according to claim 1, wherein the fibrous material forming the fibrous layer has a cut portion extending radially from the center hole to the outer periphery. (3) The semiconductor device according to claim 1, wherein a soft resin body is further fixed to the top of the fiber layer. (4) The fibrous material constituting the woven fabric or non-woven fabric is a glass fiber material.
The semiconductor device described in (1). (5) The semiconductor according to claim 1, wherein the soft resin body is silicone rubber, and the fiber layer is formed by heat treating a plate-shaped glass fiber material impregnated with epoxy resin. Device.