JPH02268446A - Manufacturing method of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent bubbles from being produced in the process of resin sealing by drying tablet-shaped sealing resin just before the sealing process so that the water content thereof may be lower than the specific percentage by weight to dried simple tablet-shaped resin substances. CONSTITUTION:A plurality of sealing resin pieces 15 are enclosed in a sealed aluminum pack 17 together with silica gel 16 to remain as they are for about two days to decrease the water content of said resin pieces 15 to 0.2% or lower to dried ones by simple substance weight. The resin pieces 15 are moved in the direction of arrow D to mount them on the specific parts of an IC chip 4 and then heated to obtain a resin-sealed device 18 in a region including the bonding electrode parts of wires 3 and conductors 2. Thereby a characteristically stable device without bubbles and with a flat surface is obtained.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for manufacturing a semiconductor device in which an IC chip mounted directly on a printed circuit board is sealed with a tablet-type sealing resin, a problem occurs in the sealing resin portion of the semiconductor device. With the aim of eliminating air bubbles, in semiconductor devices in which an IC chip mounted directly on a printed circuit board is sealed with resin, a tablet-type device is used to encapsulate a predetermined area on the printed circuit board containing the IC chip mounted directly on the printed circuit board. Dry the sealing resin immediately before the sealing process so that the water content of the tablet-type sealing resin is at least 0.2% or less by weight compared to when the tablet-type sealing resin alone is dried. and configure it.

[Industrial application field]

The present invention relates to a semiconductor device formed by encapsulating an IC chip directly mounted on a printed circuit board with a tablet-type encapsulating resin, and in particular, improves productivity and characteristics by eliminating air bubbles generated in the encapsulating resin portion of the semiconductor device. The present invention relates to a method of manufacturing a semiconductor device with improved performance.

[Conventional technology]

↓ FIG. 3 is a process diagram showing an example of a conventional semiconductor device manufacturing method, and FIG. 4 is a diagram illustrating problems.

FIG. 3, which shows a process example, shows a case where an IC chip mounted directly on a printed circuit board is sealed with resin to form a semiconductor device.

In FIG. 1, the region indicated by the broken line A indicates the resin-sealed region of the IC chip, that is, the semiconductor device forming region.

In Figure (1), 1 is a printed circuit board made of glass epoxy resin having a patterned conductor 2, for example, with a thickness of 0.5 mm. An IC chip 4 having a negative side of about 6 mm, for example, which is connected to an electrode by a wire 3, is mounted via an adhesive (not shown).

5 in the figure has a size that covers the area indicated by the broken line A above (for example, the negative side is about 12 mm) and a thickness of 0.7 to 1.5 mm.
A tablet-type sealing resin made of epoxy resin No. 01 is shown. The plurality of fine through holes 5a provided near the center of the tablet-type sealing resin (hereinafter simply referred to as sealing resin) 5 are holes for venting gas during sealing.

Here, the sealing resin 5 is placed at a predetermined position on the IC chip 4 as shown by the arrow in the figure, and the view is seen from the direction of the mark ().
2).

In this state, seal the sealing resin 5 by 150 to 170".
When heated at a temperature of A predetermined region including the bonding electrode portion of the conductor 2, that is, the region indicated by A in FIG. 1 is sealed, and a semiconductor device 6 can be obtained.

Figure (4) is a perspective view of a normally formed semiconductor device. In this case, the periphery of the IC chip 4 including the conductor 2 is completely covered with the sealing resin 5b, so it is stable. A semiconductor device 6 having such characteristics is formed.

However, in a semiconductor device formed by such a process, irregularities such as recesses may occur on the surface of the sealing resin.

Figure 4, which shows the problem, shows this situation, and (a)
(b) is a diagram showing the surface state, and (b) is a diagram showing the cross section.

In figures (a) and (b), 1 is a printed circuit board, 2 is a conductor, and 3
As in the case of FIG. 3, numeral 4 represents a wire, numeral 4 represents an IC chip, and numeral 5b represents a sealing resin.

Further, 50 in the figure indicates bubbles generated near the surface and throughout the interior of the sealing resin 5b.

As is clear from the figure, in this case, the unevenness of the surface of the sealing resin caused by the bubbles 5C causes the internal IC chip to
The semiconductor device has stable characteristics because the resin layer interposed between the surface of the IC chip 4 and the surface of the IC chip 4 becomes partially thin and the sealing effect deteriorates, or the surface of the IC chip 4 or the wire 3 is partially exposed. 6 cannot be formed.

[Problem to be solved by the invention]

Conventional semiconductor device manufacturing methods have problems in that the heat generated in the resin encapsulation process causes unevenness on the surface of the semiconductor device, reducing the encapsulation effect and making it impossible to form a semiconductor device 6 with stable characteristics. Ta.

[Failure to solve the problem]

The above-mentioned problem arises in a semiconductor device in which an IC chip mounted directly on a printed circuit board is sealed with a resin. The semiconductor device is dried immediately before the encapsulation process so that the moisture content of the tablet-type encapsulation resin is at least 0.2% or less by weight compared to when the tablet-type encapsulation resin alone is dried. The problem is solved by the manufacturing method.

[For production]

Bubbles that occur in the encapsulation resin of a resin-sealed semiconductor device that is formed directly on a printed circuit board are caused by moisture contained in the encapsulation resin being vaporized by the heat during encapsulation, and It was experimentally confirmed that the bubbles were not generated when the water content of the sealing resin was 0.2% or less by weight compared to the weight of the sealing resin alone.

In the present invention, a step of drying the sealing resin is added immediately before the step of resin-sealing a required semiconductor device to remove moisture from the sealing resin.

Therefore, it is possible to obtain a semiconductor device that does not generate bubbles even during the resin sealing process.

〔Example〕

FIG. 1 is a process diagram for explaining the method of manufacturing a semiconductor device according to the present invention, and FIG. 2 is a diagram for explaining the drying effect.

In FIG. 1(A), a tablet-type sealing resin 15 having the same shape, size, and material as the tablet-type sealing resin 5 in FIG. 3(1) is placed in an aluminum pack 17 together with silica gel 16 as a desiccant. It shows a sealed state.

Therefore, for example, a plurality of the above-mentioned sealing resins 15 having a total weight of 46 grams are hermetically sealed in an aluminum pack 17 together with 10 grams of silica gel 16 and left for about two days, and the moisture contained in each sealing resin 15 is The dry unit weight ratio of the sealing resin 15 is 0.2% or less.

On the other hand, FIG. 1(B) shows the tablet type sealing resin 5 of FIG. 3(1) replaced with the sealing resin 15 obtained in FIG. 1(A), and the other configurations are as follows. This is exactly the same as the case shown in FIG. 1(A) above.

Then, move the sealing resin 15 in the direction of the arrow to seal the IC.
A portion of the transfer sealing resin 15 placed at a predetermined position on the chip 4 is heated at 150 to 170°C to form a region including the bonding electrode portion of the wire 3 and the conductor 2, as shown in Figure (C). As explained in FIG. 3(3), the semiconductor device 18 sealed with resin is obtained in the region indicated by A in FIG. 3(B).

In this case, since the semiconductor device 18 is formed using the sealing resin 15 in a dry state with almost no moisture, the semiconductor device 18 has characteristics such as those without bubbles or surface irregularities as explained in FIG. A stable semiconductor device can be obtained.

FIG. 2, which explains the drying effect, is a graph in which the horizontal axis X shows time in days, and the vertical axis Y shows the ratio of the weight of the sealing resin alone when drying to the water content, expressed as water content in %. Each curve CI
+C2+C3 shows the change in moisture content over time when, for example, 46 grams of sealing resin with an initial moisture content of about 0.34% was sealed in an aluminum pack with the amount of silica gel changed in three stages. be.

In addition, curve C, when the amount of silica gel is 5 grams,
Curve c2 shows the experimental results when the amount of silica gel is 10 grams, and curve c3 shows the experimental results when the amount of silica gel is 20 grams. p++ of curve C5 indicated by . pz+ of curve C2 p3+ p4
+ It has been confirmed that when the sealing resin 15 is used at each point of I) s+ pb+ Pt+ of curve C3, the above-mentioned bubbles are not generated.

In addition, from the figure, sealing resin 4 with an initial moisture content of about 0.3%
In order to dry 6 grams of silica gel to the required moisture content of about 0.2%, if 5 grams of silica gel is added, it will be necessary to leave it for about 10 days.
It can be seen that if the above amount is added, the required moisture content can be obtained by leaving it for about 2 days.

[Effects of the Invention] As described above, according to the present invention, even when a tC chip mounted directly on a printed circuit board is resin-sealed, it is possible to easily produce a semiconductor device with stable characteristics in which no unevenness or bubbles are generated in the sealing resin portion. can be provided.

[Brief explanation of drawings]

FIG. 1 is a process diagram illustrating the method of manufacturing a semiconductor device according to the present invention; FIG. 2 is a diagram illustrating the drying effect; FIG. 3 is a process diagram illustrating an example of a conventional semiconductor device manufacturing method; is a diagram explaining the problem. In the figure, 1 is a printed circuit board, 2 is a conductor, 3 is a wire, 4 is an IC chip, 15 is a tablet-type sealing resin, 16 is a silica gel, 17 is an aluminum pack, 18
represent a semiconductor device, and represent a semiconductor device, respectively. Illustrations explaining the dry building effect: Figure 2, Figure 3, Figure 74.

Claims (1)

[Claims] A semiconductor device formed by resin-sealing an IC chip mounted directly on a printed circuit board, comprising: The tablet-type sealing resin (15) that encapsulates the region has a moisture content of at least 0 in weight ratio of the tablet-type sealing resin (15) when dry alone. .2% or less, a method for manufacturing a semiconductor device characterized by drying immediately before a sealing process.