JPH02265252A - Manufacturing method of semiconductor device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] A method for manufacturing a semiconductor device in which an IC chip mounted directly on a printed circuit board is sealed with a resin.
The purpose of the printing process is to prevent the IC chip from peeling off from the printed circuit board and cracks in the sealing resin that occur when other devices are soldered to the printed circuit board in the process after the C chip is sealed with resin. After the IC chip directly mounted on the board is sealed with resin, other electronic devices mounted on the printed board are soldered immediately before the work process, so that the moisture content of the printed board is at least as high as the weight of the printed board alone. Baking treatment is performed so that the ratio is 0.13% or less.

[Industrial Application Field] The present invention relates to a semiconductor device formed by resin-sealing an IC chip mounted directly on a printed circuit board, and in particular, in a process after the IC chip is resin-sealed to the printed circuit board. The present invention relates to a method of manufacturing a semiconductor device that improves productivity and characteristics by preventing peeling of an IC chip from the printed circuit board and cracking of the sealing resin that occur when connecting other electronic devices by soldering.

[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.

Figure 3, which shows an example of the process, seals an IC chip directly mounted on a printed circuit board with resin to form a resin sealing part, and then solders connectors and other electronic devices to predetermined positions on the printed circuit board. The figure shows the case where a device such as a capacitor is connected by soldering for ease of understanding.

In FIG. 1, a region indicated by a broken line A indicates a resin-sealed region of an IC chip, and a region indicated by a broken line B indicates a region to which an electronic device is soldered.

In the figure, ■ is a printed circuit board made of glass epoxy resin having a patterned conductor 2, for example, with a thickness of 0.5 mm, and at a predetermined position on the surface of the printed circuit board 1 are predetermined electrodes and wires of the conductor 2. For example, an IC chip 4 having a side of about 6 cm is mounted with an adhesive (not shown) connected thereto.

In addition, 5 in the figure has a size that covers the area indicated by the broken line A above (for example, the - side is about 12ff+m) and a thickness of 0°7~
A sealing material made of 1.0 mm of epoxy resin is shown.

Here, the sealing material 5 is placed at a predetermined position on the IC chip 4 as indicated by the arrow in the figure, and the state shown in Figure (2) as seen from the direction of the memorial seal is obtained.

In this state, heat the sealant 5 part to 150~170'C.
When heated, the sealing material 5 softens and begins to hang down from its periphery, resulting in a region including the bonding electrode portion of the wire 3 and the conductor 2 as shown in FIG. 3 (FIG. 1). The region indicated by A is sealed with resin to obtain a resin-sealed portion 6.

Next, a predetermined electronic device 7 is placed in area B in FIG.
Freon-based liquids (e.g. product name:
Chamber 1 containing Fluorinert (manufactured by Sumitomo 3M■) 9
The solder base 8 is melted and the device 7
A solder connection is made to the conductor 2.

FIG. (4) shows this state, and by taking it out from the chamber 10, the circuit in which the required resin-sealed part 6 and electronic device 7 are mounted is sealed with resin as shown in FIG. (5). A substrate 11 can be obtained.

On the other hand, in order to mount connectors and other devices by soldering on a transferred printed circuit board with a resin-sealed portion formed on the printed circuit board, as described above, for example, exposure to a high-temperature chlorofluorocarbon gas atmosphere is necessary. However, the heat generated at this time may cause the rC chip to peel off from the printed circuit board or cracks may occur in the sealing resin.

FIG. 4, which shows these problems, shows the resin-sealed portion, which is the main part, in cross section.

Figure (A) shows the resin sealing part in a normal state, where l is a printed circuit board, 2 is a conductor, 3 is a wire, and 4 is an IC.
As in the case of FIG. 3, the chips and 5 each represent a sealing material, and a normal resin sealing portion 6 is formed by each of these components, as in the case of FIG.

In this case, since the periphery of the IC chip 4 including the conductor 2 is completely covered with the sealing material 5, a resin sealing portion 6 having stable characteristics is formed.

Furthermore, Figure (B) shows a state in which a crack 6a has occurred around the resin sealing part 6, reaching the IC chip 4.
In this case, the IC chip 4 and the wires 3 inside are partially exposed, which induces a deterioration of the characteristics, and there is a risk that the exposed portions will be damaged, for example, by cutting the wires 3 or peeling off the bonding portions.

Further, in Figure (C), the printed circuit board l peels off from the IC chip 4 on the back side of the resin sealing portion 6, that is, on the printed circuit board 1 side, and bulges, creating a gap 6b between the printed circuit board 1 and the IC chip 4. In this case, the sealing with the resin material 5 becomes incomplete, and there is a risk that the characteristics will deteriorate or the device will be destroyed.

[Problems to be Solved by the Invention] In the conventional manufacturing method of semiconductor devices, soldering in the post-process has problems such as cracks occurring in the resin sealing part and deformation and swelling of the printed circuit board during the work process. there were.

[Means for solving the problem] The above problem is that after the IC chip mounted directly on the printed circuit board is sealed with resin, the soldering of other electronic devices mounted on the printed circuit board must be done at least immediately before the work process. The problem is solved by a semiconductor device manufacturing method in which a baking treatment is performed so that the moisture content of the printed circuit board is 0.13% or less by weight compared to the printed circuit board alone.

[Function] When soldering a device after forming a resin sealing part on a printed circuit board, cracks may occur due to the heat during soldering, and deformation such as swelling of the printed circuit board due to nuclear heat may occur due to moisture contained in the printed circuit board being vaporized. It was confirmed that the above-mentioned defect phenomenon does not occur when the moisture content of the printed circuit board is 0.13% or less in terms of weight ratio of the printed circuit board alone. .

In the present invention, the transferred printed circuit board with the required resin sealing portion formed on the printed circuit board is subjected to baking treatment to reduce the moisture content of the printed circuit board to almost zero, and soldering of other electronic devices is carried out in this state. The method for manufacturing a semiconductor device is configured to do so.

Therefore, it is possible to obtain a semiconductor device in which no cranking occurs even when heat is applied during soldering, and the printed circuit board does not deform.

〔Example〕

FIG. 1 is a process diagram illustrating a method for manufacturing a semiconductor device according to the present invention, and FIG. 2 is a diagram illustrating the basis for limiting the moisture content of a printed circuit board.

In FIG. 1, (A) shows a state in which the resin sealing portion 6 is formed on the printed base Fil in the steps explained in FIGS. 3 (1) to (3).

Note that area B indicated by the broken line is an area where electronic devices are mounted, as in FIG.

Here, the printed circuit board 1 is placed in the constant temperature bath 15 shown in FIG. 1B in this state, and subjected to baking treatment in which it is left at 125° C. for 12 to 24 hours to remove moisture contained in the printed circuit board 1.

After taking it out, the electronic device 7 is placed on the printed circuit board at a predetermined position, that is, the area B in FIG. The state shown in (C) is obtained.

Here, as shown in FIG. 3(D), the electronic device 7 is set in an atmosphere of high-temperature fluorocarbon gas 9a in the chamber 10 configured similarly to FIG. 3(4), and solder connection of the electronic device 7 is performed. There is.

In this case, the printed circuit board 1 is normally exposed to the atmosphere from the time it is taken out from the thermostat 15 shown in Figure (B) until it is put into the chamber 10 shown in Figure (D). Absorbs moisture.

Therefore, it is desirable that the time during this period be as short as possible, and usually within about 2 to 3 hours.

In this method of manufacturing a semiconductor device, soldering can be carried out in a state where almost all the moisture contained in the printed circuit board 1 has been removed, so that cracks may occur in the resin sealing part due to the heat generated during the soldering process. Furthermore, the printed circuit board itself does not undergo deformation such as swelling.

Figure 2, which explains the basis for limiting the moisture content of printed circuit boards, 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 a single printed board to the moisture content as a percentage. and each curve c,,c z.

c3 shows the degree of water absorption over time when a printed circuit board with an initial moisture content of "0" was exposed to three different atmospheres.

Note that the curve c1 has a temperature of 25° C. and a humidity of 45% R,H.

Curve C2 represents the case where the temperature is 25° when left indoors.
Curve C1 is the experimental result when left in an atmosphere with a humidity of 60% R, H, and curve C1 is left in an atmosphere with a temperature of 30'' and a humidity of 80% R, H.

In addition, the points indicated by ・ on each curve indicate cracks in the resin sealing part and cracks in the printed circuit board when soldering is performed in the process explained in Figure 3 using the printed circuit board extracted under the corresponding conditions. This shows the case where no deformation such as blistering (hereinafter referred to as defective point) occurred, and the points marked with an x on each curve indicate the case where the above-mentioned defective point occurs when the printed circuit board extracted under the corresponding conditions is used. indicates that it has occurred.

For example, in curve C0, there are 21 points, that is, the moisture content is 0.08.
The above-mentioned problems do not occur in the case of 4% and the P2 point, that is, the case of the water content of 0.13%, but the above-mentioned problems occur in the case of 98 points, that is, the case of the water content of 0.17%.

Similarly, in curve C2, there are 23 points, that is, the water content is 0.13.
No defects occur when the water content is 2%, but the moisture content is 0.19.
This indicates that a defective point occurs after 93 points, which is 4%.

The same applies to the curve c3.

Therefore, each curve c1. Pl-Qz- on c2', c,
From the existence area of each point, at least if the moisture content of the printed circuit board during soldering is 0.13% or less, it is possible to obtain a semiconductor device that does not have the above defects caused by the heat during soldering. can.

Note that from each of the above-mentioned curves cl, cz, and c3, it is possible to approximately determine the limit of the time from diagram (B) to diagram (D) in the process explained in FIG.

〔Effect of the invention〕

As described above, according to the present invention, soldering of electronic devices after forming a resin sealing portion on a printed circuit board is a step in which the printed circuit board is deformed and the IC chips are peeled off from the printed circuit board. Accordingly, it is possible to provide a semiconductor device that does not suffer from problems such as cranking.

[Brief explanation of drawings]

The first part is a process diagram explaining the method for manufacturing a semiconductor device according to the present invention, the second part is a diagram explaining the basis for limiting the moisture content of a printed circuit board, and the third part is a process diagram showing an example of a conventional semiconductor device manufacturing method. Figure 4 is a diagram explaining the problem. In the figure, 1 is a printed circuit board, 4 is an IC chip, 6 is a resin sealing part, 7 is an electronic device, 8 is a solder paste,
9a is a freon gas, 10 is a chamber, 15
represents a constant temperature bath. (B) (D) Akira 1 Figure (?≦) (f) 1 print Hiruki anti-r5 Kore Mamegubun and Soraji B month T5 Tatsuguchi

Claims (1)

[Claims] After the IC chip (4) directly mounted on the printed circuit board (1) is sealed with resin, at least immediately before the soldering process of other electronic devices mounted on the printed circuit board (1). The printed circuit board (
The water content in 1) is 0.0% by weight compared to the printed board alone.
1. A method of manufacturing a semiconductor device, comprising performing a baking treatment to reduce the concentration to 13% or less.