JPH04176134A - Manufacture of resin sealed semiconductor device - Google Patents

Abstract

PURPOSE:To minimize the elasticity recovery amount of a resin occurring at the molding pressure releasing time while avoiding the deterioration in moisture resistance and the disconnection of gold wire by a method wherein the product is taken out of a metallic mold after performing the heat molding step for the time when the set contraction of the resin is finished to minimize the elasticity recovery amount. CONSTITUTION:During the resin sealing process wherein a resin is poured in a cavity through a runner to be filled up for setting out of the title manufacturing processes of a resin sealed semiconductor device, the product is to be taken out of a metallic mold after performing the heat molding step of the resin for the time when the elasticity recovery does not depend upon the molding time after finishing the set contraction. For example, the molding processes are performed meeting the requirements such as the molding temperature of 175+ or -5 deg.C, molding pressure of 100kg/cm<2>, molding time of 120sec and resin pouring rate of 24sec. At this time, in proportion to the elapse of molding time, the elasticity recovery and the actual swelling amount of the semiconductor device are decreased while effecting no set contraction at all and stabilizing the elasticity recovery amount when the molding time of 120sec elapsed. Through these procedures, the mold resin separation due to the elasticity recovery, the deterioration in the moisture resistance and the disconnection of gold wire can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a molding method in a resin sealing process (mold forming) of a resin-sealed semiconductor device.

(Prior art) In the molding process of manufacturing resin-sealed semiconductor devices, resin is injected into a cavity formed by a mold and cured by heating.This method reduces the curing time of the resin. However, in order to prevent the air in the cavity from escaping and voids being generated in the resin, a conventional method has been proposed as disclosed in Japanese Patent Laid-Open No. 16533/1983. The main point of this means is that during the process of injecting the resin into the cavity through the runner, the mold is heated at a temperature lower than the predetermined curing temperature of the resin.
During the resin curing step, the mold is heated at the predetermined curing temperature.

(Problem to be Solved by the Invention) However, even if the molding is performed using the method described above, if the mold is opened and the molded product is taken out while the curing reaction of the resin is insufficient within the mold, the cured resin may Due to the elastic recovery, peeling occurs at the interface between the semiconductor element surface and the molding resin, resulting in problems such as reduced moisture resistance and the gold wire connecting the semiconductor element and external terminals being stretched and broken.

The above-mentioned conventional example does not take this point into consideration, and the present invention attempts to solve this problem by reducing the elastic recovery of the resin that occurs when molding pressure is released, thereby reducing moisture resistance deterioration and gold wire breakage. The purpose is to prevent

(Means for Solving the Problems) The present invention, as a means to solve the above-mentioned problems, provides that, in the resin sealing process, the time required for curing and shrinking of the resin to finish and for its elastic recovery to be minimized, after molding, The molded product can now be removed from the mold.

(Function) As described above, in the present invention, the molded product is molded until the elastic recovery of the cured resin product is minimized, and then the molded product is not removed from the mold.
This prevents the mold resin from peeling off due to elastic recovery, and prevents deterioration of moisture resistance and breakage of the gold wire.

(Example) In explaining the present invention in detail, first, a method for examining the cured state of a resin and the concept of a measurement example thereof are shown in FIG. 1 and will be described below.

FIG. 1(a) is a schematic diagram of measuring the melting and hardening state of a resin tablet using a Koka-type flow tester. Normally, in measurements using this Koka type flow tester, a through hole is provided in the center of the bottom 3 of the heating furnace (bot) 2 shown in Figure (a) so that the molten resin flows out, but in this example In this case, one without a through hole was used. By doing so, the expansion and contraction of the resin tablet 4 in the heating furnace 2 can be measured from the amount of vertical displacement of the plunger 1, and the melting and hardening state of the resin tablet 4 can be investigated.

Melting and hardness of resin tablet 4 measured by this method =
FIG. 1(b) is a conceptual diagram showing the state and changes in the plunger stroke amount due to elastic recovery when the plunger 1 is removed.

In this example, a resin tablet 4 with a cross-sectional area of 1 cm' and a height of 15 cm is placed in a heating furnace 2 heated to a molding temperature.
The plunger 1 with a load equivalent to the molding pressure is placed in the heating furnace 2.
I made it descend inside.

Hereinafter, the state changes will proceed from left to right in FIGS. (a) and (b), so the description will be made accordingly.

The resin tablet 4 is melted by heating, its volume is reduced, and the plunger 1 is further lowered. Therefore, the plunger 1-loak amount increases as shown in Figure (b).

Next, the molten resin 4 begins to thermally expand, and the plunger l is pushed up (the plunger stroke amount decreases), but once the curing reaction begins, it hardens and shrinks, decreasing the volume, so the plunger stroke amount decreases. It will increase again. When the load is removed after the molding time, the balance between the compressive force and the expansion force due to heat is lost, and the volume of the cured resin 4 increases, that is, it recovers elastically, pushing the plunger l upward. That is, the stroke amount suddenly decreases as shown by the rightmost line in the figure (b).

Changes in melting and curing of resin basically follow the process described above, but as an example, the elastic recovery point of the cured resin of a semiconductor device molded in an actual mold was measured using a surface roughness meter. Examples and their swelling states are shown in Figure 2 (a), (b), and (c).
Shown below.

As can be seen from the figure, as the molding time becomes longer, the elastic recovery and the swelling of the actual semiconductor device become smaller, curing shrinkage disappears, and when the molding time is reached, the amount of elastic recovery becomes constant. At this stage, the adhesive force between the mold resin and the surface of the semiconductor element becomes stronger than the elastic recovery force, and no gap is formed at the interface that would cause deterioration of moisture resistance.

Therefore, if the molded product is removed from the mold at this stage, a semiconductor device without deterioration in moisture resistance can be obtained as described above.

The authors manufactured the actual product under the following conditions and were able to obtain a fully satisfactory product, which is described here for reference.

Molding conditions Molding temperature: 175±5°C Molding pressure: 100 K g/cm 2 Molding time: 120 sec Resin injection speed: 24 sec An elastic recovery amount of 100 μm was obtained under the above conditions.

In addition, the results (number of defective products) of a moisture resistance test and a temperature cycle test of resin-sealed semiconductor devices conducted at molding times of 40 seconds, 80 seconds, and 120 seconds are shown below.

85℃/85%R,H, operation test Number of samples: 30 Temperature cycle test Number of samples: 50 The defect is a broken wire. That is, there were no defective products when the molding time was 120 seconds.

(Effects of the Invention) As explained above, according to the present invention, in the resin molding process of a resin molded semiconductor device, molding is performed until curing and shrinkage at the molding temperature are completed and the elastic recovery of the resin is minimized. This makes it possible to prevent the surface of the semiconductor element from peeling off from the mold resin due to the elastic recovery of the resin, and to realize a semiconductor device with extremely high reliability without deterioration in moisture resistance or breakage of the gold wire.

[Brief explanation of drawings]

FIG. 1 is an example of measurement of the cured state of the resin, and FIG. 2 is an explanatory diagram of the amount of elastic recovery in an example of the present invention. ■・・・・・・・・・Plunger, 2・・・・・・・・・Heating furnace, 3・・・・・・・・・Bottom, 4・・・・・・・・・Resin Tablet.

Claims (1)

[Claims] In the manufacturing process of resin-sealed semiconductor devices, in the resin-sealing process in which resin is injected into a cavity through a runner, filled, and cured, curing shrinkage of the resin is completed and elastic recovery is achieved. A method for manufacturing a resin-sealed semiconductor device, characterized in that the molded product is removed from the mold after being heated and molded for a time that is independent of the molding time.