JPS6110260A - Manufacture of resin-sealed type electronic component - Google Patents

Abstract

PURPOSE:To enable the inhibition of crack generation by using an epoxy series resin of high thermal conductivity by a method wherein sealing is carried out with a molding resin produced by the addition of a butadiene series polymer to the mixed resin of cresol novolak epoxy resin with phenol novolak resin. CONSTITUTION:The electronic component assemblage is sealed with the molding resin produced by addition of a butadiene series polymer to the mixed resin of cresol novolak epoxy resin with phenol novolak resin. It is suitable to choose the amount of addition of the butadiene series polymer in a range of 0.05-10.0wt%, and the molding temperature for the electronic component assemblage in a range of 150-190 deg.C. This manner enables the production of electronic components with less generation of cracks by using an epoxy series resin of high thermal conductivity as the molding resin.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a resin-molded part of an electronic component assembly structure, which is designed to reduce molding resin stress that occurs at a portion where the thickness changes or at a boundary between the resin-molded part and the molded resin. The present invention relates to a method for manufacturing resin-sealed electronic components that can eliminate cracks that occur in molded resin due to cracks and improve crack resistance and reliability.

Conventional configurations and their problems In recent years, resin sealing structures have been widely adopted as sealing structures for reducing production costs and improving mass productivity of various electronic components. In addition, condensation resins such as epoxy resins and silicone resins are widely used as molding resins, but epoxy resins are superior to other resins in terms of material cost, and in resin-sealed electronic components, Sealing with epoxy resin is often used.

On the other hand, when manufacturing resin-sealed electronic components, it is necessary to pay attention to the performance of quickly dissipating the heat generated during actual operation to the outside. is being done. These performance requirements are particularly strict when the electronic component is a semiconductor device.
For example, consideration has been given to the sealing structure to minimize the thickness of the molded resin that covers the back side of the semiconductor element assembly structure, and the amount of filler added is increased to increase the thermal conductivity of the molded resin itself. Consideration is also given.

By the way, epoxy resin has a larger curing shrinkage during molding and higher resin stress than silicone resin. In addition, silica powder is widely used as a filler for epoxy resins, but
When considering the purpose of increasing thermal conductivity, crystalline silica is more effective than fusible silica. However, when a large amount of crystalline silica is added, both the coefficient of thermal expansion and the shrinkage rate become extremely large. Therefore, in electronic parts sealed and molded with this epoxy resin, cracks are likely to occur in the molded resin layer, resulting in a decrease in insulation or moisture resistance. The occurrence of cracks is mainly seen at the boundary where the thickness of the electronic component assembly structure changes, or at the interface between the peripheral area and the molded resin. It is presumed that the difference in thermal expansion coefficients is the cause of cracks.

Figure 1 shows that an epoxy resin with comparatively high sintering conductivity is used as the molding resin, and the bonded area of the semiconductor substrate has a function as a heat dissipation plate.Furthermore, the thickness of the lower molded resin layer is made thinner to dissipate heat. FIG. 2 is a diagram showing a cross-sectional structure of a resin-sealed semiconductor device for electric power with improved effects. As shown in the figure, the molded resin layer 2 on the back side of the semiconductor substrate support part 1 of the semiconductor element assembly structure is thin, while the molded resin layer 3 on the front side is thick, so that molding and sealing is achieved. There is. In a power resin-sealed semiconductor device that is molded and sealed in this manner, cracks are likely to occur in the molded resin at the interface 4 corresponding to the above-mentioned location.

FIG. 2 shows the ratio (B/A) between the total resin thickness A of the molded resin layer and the thickness B of the molded resin layer 2 on the back side of the power resin-encapsulated semiconductor device shown in FIG. This figure shows the results of a thermal shock accelerated test of 6 minutes each at -66°C and +150°C to compare the occurrence of cracks in these samples, in which B/A- The relationship between the crack occurrence rate and the number of thermal shock cycles is shown for the samples in which the first and second rows are B/A-row, and the third row is B/A=34. As shown,
As the thickness B of the molding phase or fat layer 2 becomes thinner with respect to the total resin thickness A, the incidence of cracks in the molded resin layer increases, and moreover, cracks occur with fewer thermal shock cycles.

As described above, when an epoxy resin having relatively high thermal conductivity is used as a molding resin, the problem of cracks occurring in the molding resin cannot be avoided.

Furthermore, this problem becomes more pronounced as the thickness of the molded resin layer covering the back side of the assembled structure is reduced in order to increase the dissipation of heat generated during operation to the outside.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a method for manufacturing resin-sealed electronic components that uses an epoxy resin with high thermal conductivity as a molding resin and can suppress the occurrence of cracks.

Structure of the Invention The method for manufacturing a resin-sealed electronic component of the present invention uses, as a molding resin, a mixed resin of a cresol novolac epoxy resin and a phenol novolac resin to which a butadiene-based polymer is added at a predetermined weight ratio. This method is characterized by molding and sealing electronic component assembly configurations using molded resin.

According to the manufacturing method of the present invention, flexibility is added to the molded resin by adding a butadiene-based polymer, which reduces shrinkage during sealing molding and the difference in thermal expansion coefficient between the electronic component assembly structure and the molded resin. This eliminates the inconvenience of cracks occurring in the molded resin due to stress.

Description of examples The present invention will be explained in detail below.

A butadiene-based polymer that acts as a flexibilizer is added to the molding resin used in the production method of the present invention. Although this butadiene-based polymer imparts flexibility to the molded resin, it acts in a direction that reduces the heat transfer of the molded resin, and also changes the fluidity that the epoxy resin originally has.

Figure 3 shows the mixture ratio of Talesol novolac epoxy resin and phenol novolac resin selected, and butadiene nitrile rubber as a butadiene-based polymer is added to the molded resin with a thermal conductivity of about 65 x 10'CILlll flat type 0℃. It is a figure which shows the experimental result which investigated the thermal conductivity change of molding resin by adding and changing the addition amount. As shown, m m IF l) of butadiene nitrile rubber
There is no significant decrease in thermal conductivity up to 10.0 Jl bar cent. However, if the amount added exceeds this value, a significant decrease in thermal conductivity will occur.

FIG. 4 is a diagram showing the results of an experiment in which the fluidity of molded resin was investigated by varying the amount of butadiene nitrile rubber added, similar to the above. The spiral flow of the molding resin that can be molded under normal molding conditions is approximately 506. By the way, as is clear from the figure, if the amount of butadiene nitrile rubber added exceeds about 12% by weight, the spiral flow will reach 50 (B or less), making mold sealing impossible. In order to obtain a molding resin that does not significantly reduce its thermal conductivity and does not interfere with mold sealing, it is necessary to limit the amount of getadiene polymer added to 10.0% by weight or less. Yes.

Figure 6 shows six types of molded resins obtained by varying the amount of getadiene polymer added to a mixed resin of Talesol novolac epoxy resin and phenol novolac resin, and molded resins to which no getadiene polymer was added. 2 is a diagram illustrating a comparison of the thermal shock acceleration test results obtained by manufacturing resin-sealed power semiconductor devices using the following methods. 4 in the diagram
1 bite.

For c, 2 and e, the amount of getadiene polymer added is 0.
．． 02.0.05.0.5, 1.0 and 10.0% by weight of molding resins were used. The relationship between the thermal shock cycle and the crack incidence rate is shown when using a molded resin that has not been used. As is clear from the diagram, compared to the molding resin that does not contain butadiene-based polymers,
Cracking resistance is dramatically improved when a molding resin containing 0.06 7 cents by weight or more of a butadiene polymer is used. In addition, butadiene-based polymer is 0.0
Even when using a molding resin containing 2% by weight,
Although the crack resistance is significantly improved compared to the molding resin that does not contain butadiene-based polymers, the molding resin has a cracking rate of 2Q% after about 40 thermal shock cycles. It is not desirable to mold and seal the actual product. That is, in consideration of crack resistance, the lower limit of the amount of getadiene polymer added is preferably about 0.06 weight percent.

As explained above, if the butadiene-based polymer used as a flexibilizer is added in a weight ratio of 0.06 to 10.0%, the thermal conductivity will not decrease and the crack resistance will improve dramatically. The resin sealing layer enables sealing molding of electronic components with improved performance. Note that when the molding temperature when using the molding resin of the present invention is 150° C. or lower, the viscosity of the molding resin does not decrease, resulting in an unfilled state in the cavity of the sealing mold. On the other hand, if the temperature exceeds 190° C., the curing speed becomes faster and the burnt cavity may not be filled. Therefore, the molding temperature range is preferably 150°C to 190'C.

In the above explanation, a resin-sealed semiconductor device was exemplified, but
The manufacturing method of the present invention can be widely applied to sealing molding of other electronic components.

Effects of the Invention According to the method of manufacturing a resin sealing layer electronic component of the present invention, it is possible to manufacture an electronic component with fewer cracks by using an epoxy resin with high thermal conductivity as a molding resin. It is possible to increase the power and reliability of resin-sealed layer electronic components.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a resin-sealed semiconductor device for power use, and Figure 2 is a cross-sectional view of the resin-sealed semiconductor device for power use shown in Figure 1 when the ratio of the total resin thickness to the back side resin thickness is changed. Fig. 3 shows the change in thermal conductivity depending on the amount of butadiene nitrile rubber added to the molding resin, Fig. 4 shows the relationship between the cracking rate and the number of thermal shock cycles. A diagram showing the relationship between the amount of rubber added and the spiral flow. Figure 6 shows power resin encapsulation molded with molding resins with varying amounts of butadiene-based polymers and molding resins without butadiene-based polymers. FIG. 3 is a diagram showing comparison results of crack resistance of semiconductor devices. 1... Semiconductor substrate support part, 2... Molded resin layer on the back side, 3... Molded resin layer on the front side,
4...Interface where cracks are likely to occur. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Fig. 2 Thermal shock sipe J to 43ζ,
Budadiene Nitoso I record attachment (”%)
5th cause 0 20 40 60 80 Ioo 120
Ha I60 20θ valve external balance fsile number (rotation

Claims (3)

[Claims] (1) A method for manufacturing a resin-sealed electronic component, which comprises sealing an electronic component assembly with a molding resin made by adding a butadiene polymer to a mixed resin of a cresol novolac epoxy resin and a phenol novolac resin. . (2) The amount of butadiene polymer added is 0.05 to 10
．． 2. The method for manufacturing a resin-sealed electronic component according to claim 1, wherein the content is selected within a range of 0 weight percent. (3) Molding temperature of electronic component assembly structure is 150 to 190℃
2. The method for manufacturing a resin-sealed electronic component according to claim 1, wherein the resin-sealed electronic component is selected within the range of .