JPS6013132B2 - Method for measuring resin curing stress in resin molded bodies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a technology for measuring curing stress of resin in resin encapsulation, and is mainly directed to resins for resin-encapsulated semiconductor devices.

Semiconductor devices such as ICs and LSIs sealed with epoxy resin or the like are constructed from a combination of materials such as resins, semiconductors, and metals that differ in their physical properties such as thermal expansion coefficients and elastic coefficients. .

Such resin-sealed bodies have internal stress due to a complex interplay of various factors, and as a result of the addition of thermal stress under harsh thermal cycle temperature conditions, the seal may be damaged or the silicon beret may be destroyed. The protective insulating film on the surface of the pellet may crack, and the protective insulating film itself may peel off, reducing moisture resistance. Sometimes the boundary between the epoxy resin and the pellet peels off, allowing moisture to infiltrate.
Corrosion may occur in the internal aluminum wiring layer, resulting in disconnection. In order to solve these problems, it is necessary to quantitatively understand the internal stress generated within the resin during curing. However, in conventional resin molding technology, only the injection pressure and molding temperature are controlled to match the resin, and almost no actual measurement data regarding the curing stress of the resin is known. Moreover, there has been no report on a method for correlating and measuring internal pressure and temperature changes during resin curing. The present invention was made by focusing on the use of strain gauges to actually measure the curing stress of resin in combinations of resin and various materials, and by quantitatively understanding the internal stress generated during resin molding, mechanical The purpose of this invention is to solve electrical and chemical problems and thereby provide better resin-sealed products, especially resin-sealed semiconductor devices.

In order to achieve the above object, an embodiment of the present invention provides a method for measuring resin curing stress in a resin sealed body, in which a cylinder of a predetermined size standard made of the same material as the member to be sealed is prepared,
The purpose of this project is to attach a strain gauge and thermocouple to the inner surface of this cylinder, and mold a sealing resin material to the outer surface of the cylindrical sensor, and measure the tightening strain generated at that time in relation to temperature. .

A detailed explanation will be given below based on examples.

FIG. 1 shows the configuration of a resin mold when measuring resin curing stress according to the present invention, where 1 is an upper mold, 2 is a lower mold, and 3 is a thin cylindrical sensor prepared for the measuring method according to the present invention. , 4 is a ring that prevents resin leakage and supports the expansion and contraction movement of the cylindrical sensor, 5 is a resin (monomer) injection port, and 6 is a strain gauge lead outlet.

The cylindrical shape and dimensions of the thin-walled cylindrical sensor are shown in FIGS. 2a and 2b.

Examples of cylindrical materials include '1} Kovar alloy '{2}
Copper, {3} Steel, {4} Aluminum, '5} SU
There are S etc. To measure the resin curing stress of the resin sealing body, a strain gauge 7 and a thermocouple 8 are attached to the inner surface of the cylindrical sensor as shown in FIG. Resin molding is applied to the outer surface of the cylinder.

FIG. 3 shows the form of a pressure sensor molded with resin body 9. As shown in FIG. FIG. 4 shows the change in density when molding epoxy resin in relation to temperature.

In the figure, the powdered resin (monomer) indicated by point A becomes liquid as the temperature increases and is injected into the T-mold (A→B). Polymerization and curing shrinkage occur at the curing temperature (B→C→D), and the temperature reaches room temperature F as a solid (polymer). C is the gel point, and E is the point at which the epoxy resin transitions from a rubber-like elastic body to a glass state. As mentioned above, since the resin shrinks considerably from the curing process to the heat shrinking process, it is thought that a large amount of stress also exists. In order to quantitatively know the stress in the resin during the process from curing to heat contraction, the thin-walled cylindrical sensor described above is used.If the sensor is molded with resin, as shown in FIG. 3 contracts like 3'. At this time, the hardening stress or force is applied to the outer surface of the cylinder in the direction of the arrow in the figure. Therefore, it is possible to measure the tightening stress or corresponding to each temperature using the strain gauge and heat chamber pair attached to the inner surface. The measured value of resin curing stress using a strain gauge is
This can be determined by applying hydraulic pressure to the outside surface of the cylinder and comparing it with the pressure. This cylindrical sensor can be used to measure the influence of injection pressure during resin molding. FIG. 6 shows the results obtained by the resin curing stress measuring method according to the present invention.
This figure shows the results of measuring changes in vertical stress and temperature over time for a cylindrical sensor made of steel with a 0.4 gauge plate for a certain kind of epoxy resin.

In the same figure, the temperature drops once during molding (136
0), the curing temperature (180 qo) is reached, while the stress becomes 0 after the injection pressure reaches its maximum, after which the cooling process begins and the vertical stress strain r due to resin curing gradually increases.
After reaching room temperature (25℃) in about 30 minutes. r is 1.4
It has been shown that he will be a k9/grandchild. As described above, according to the present invention, by carefully selecting the resin material to be molded and the member to be molded, it is possible to obtain a correlation between stress during curing. This invention is not limited to the above-mentioned embodiment, but has various modifications as described below.

{1} When actually measuring resin mold distortion.

In other words, the correlation between the resin Q and the sealing material Q can be obtained. '21 When performing actual measurements using after-cure.

For example, it is possible to grasp the progress of resin curing during secondary baking. {31 When measuring the state of strain when subjected to temperature cycles. The present invention is applicable to resin-encapsulated semiconductor devices and other resin-encapsulated products in general.

[Brief explanation of the drawing]

Fig. 2 is a cross-sectional view of a resin mold for measuring resin curing stress according to the present invention, Fig. 2 a and b are a plan view and a front cross-sectional view showing an example of the shape and dimensions of the cylindrical sensor used in the present invention. Fig. 3 is an explanatory diagram showing the form of a pressure sensor in which a strain gauge and a thermocouple are attached to a cylinder and molded with a resin body, Fig. 4 is a graph showing a ratio change curve during the resin curing process, and Fig. 5 is an illustration of a pressure sensor molded with a resin body. FIG. 6 is an explanatory diagram showing the direction of curing strain of the resin with respect to the cylinder in the method of the invention. FIG. 6 is a curve diagram showing changes over time in temperature and vertical stress or when molding a resin measured by the method of the invention. 1... Upper die, 2... Lower die, 3... Cylindrical sensor "4.
...0 ring 5...Resin injection port, 6...
Strain gauge lead outlet, 7...Strain gauge, 8...
Heat turtle pair, 9...Molded resin body. Figure 2 Figure 3 Disciple Prisoner's Return Figure 6

Claims (1)

[Claims] 1. Prepare a cylinder of predetermined dimensions made of almost the same material as the member to be sealed, attach a strain gauge and a thermocouple to the inner surface of this cylinder, and mold a sealing resin material to the outer surface of this cylinder, A method for measuring resin curing stress in a resin-sealed body, characterized by measuring the strain generated at that time in relation to temperature.