JPH0533307Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application This invention relates to a cushion material for hot press forming, which is used, for example, during pressure molding of printed circuit boards such as rigid printed circuit boards and flexible printed circuit boards.

(b) Conventional technology Conventionally, cushion materials for molding presses for pressure molding the above-mentioned printed circuit boards include, for example, multiple layers of paper such as kraft paper, nonwoven fabrics such as felt, and polymer film sheets. They were used either alone or reinforced with cloth, other films, mesh, etc.

(c) Problems to be Solved by the Invention Since the cushion material mentioned above is formed flat, it inevitably has the disadvantage that the outer circumference becomes thinner and tends to warp or distort. For this reason, the wall thickness of the outer periphery of the molded printed circuit board becomes thinner, and if thickness unevenness occurs on the outer periphery, distortion and warping occur, making it more likely to cause problems when mounting components. .

In view of the above problems, this idea was developed by applying a higher pressure to the central part of the cushion material than to the outer periphery, allowing printed circuit boards to be bonded without any gaps and pressure molded to a flat, uniform thickness with good quality. The purpose of the present invention is to provide a cushion material for a molding press that can mold printed circuit boards.

(d) Means for solving the problem This invention is characterized by a cushion material in which a reinforcing material having a higher elastic modulus than the elastic material is embedded in the center of the cushion material formed of an elastic material. .

(e) Effect This invention is a cushion material for heat press molding during printed circuit board molding, so the pressure force is higher at the central part where the reinforcing material is embedded than at the outer periphery of the cushion material, so it is easier to mold printed circuit boards. The air bubbles that exist between the adhesive surfaces move from the center where the pressure is high to the outer periphery where the pressure is low.
The air bubbles are removed to the atmosphere side, and the printed circuit board is sequentially pressed from the center toward the outer periphery, and the bonding surfaces are bonded without any gaps.

In addition, since the pressure applied to the outer periphery of the cushion material is lower than that at the center, it is possible to actively prevent the molten adhesive from flowing out between the adhesive surfaces of the printed circuit board, and the molded printed circuit board is flat and uniform. Formed in thickness.

(f) Effects of the invention According to this invention, although the cushion material has a flat appearance, the pressure force is higher at the center than at the outer periphery, so the printed circuit board is Pressure is applied sequentially from the beginning to the outer periphery, and the printed circuit board can be adhered without any gaps while removing air bubbles, resulting in high adhesive strength.

Moreover, since it actively prevents the adhesive from flowing out between the adhesive surfaces of the printed circuit board, it is possible to form the molded printed circuit board with a flat and uniform thickness, eliminating distortion and warping due to uneven thickness. The occurrence of such problems is reduced, and quality can be improved and stabilized.

(g) Example of the invention An example of the invention will be described below in detail based on the drawings.

The drawings show cushion materials used for pressure molding of printed circuit boards, and in FIGS. 1 and 2,
This cushion material 1 is made of a sheet body 2 made of an elastic material with high cushioning properties and a low elastic modulus, such as silicone rubber, and reinforced with carbon fiber, aramid fiber, glass fiber, etc., which has a higher elastic modulus than silicone rubber, in the center of the sheet body 2. A plurality of three types of reinforcing sheets 3, 4, and 5 made of a square material are buried in order of increasing area ratio from large to medium.

The sheet main body 2 described above is formed in a size corresponding to the printed circuit board 6 described later, and has a total thickness of 1 mm to 3 mm when a plurality of three types of reinforcing sheets 3, 4, and 5 are laminated. In this case, one reinforcing sheet 3 formed in a large area has a wall thickness of 0.21 mm to 0.4 mm, and two reinforcing sheets 4 each formed in a medium area,
4, each of two reinforcing sheets 5 formed in a small area,
5 is formed to have a wall thickness of 0.06 mm to 0.08 mm.

Each of the above-mentioned reinforcing sheets 3, 4, and 5 has one reinforcing sheet 3 formed in a large area disposed in the central part of the above-mentioned sheet main body 2 in the thickness direction, and the thickness around this reinforcing sheet 3 is Two reinforcing sheets 4, 4 each having a medium area are disposed facing the center surface of the reinforcing sheet 3 at the upper and lower positions in the direction, and furthermore, at outer positions of these reinforcing sheets 4, 4, 2 formed in a small area facing the center surface of each reinforcing sheet 4, 4
Two reinforcing sheets 5, 5 are provided, respectively.

That is, a large-area reinforcing sheet 3, medium-area reinforcing sheets 4, 4, and small-area reinforcing sheets 5, 5 are buried at predetermined equal intervals and placed in the center of the sheet body 2. Centering around the reinforcing sheet 3, medium-area reinforcing sheets 4, 4 and small-area reinforcing sheets 5, 5 are arranged so that the area becomes smaller in the thickness direction.

The area ratio of each of these reinforcing sheets 3, 4, 5 is: Sheet Large area Medium area Small area Main body Reinforcement sheet Reinforcement sheet Reinforcement sheet 1:0.200:0.100:0.010 ~ ~ ~ 0.400 0.200 0.100 becomes.

Pressure molding of the printed circuit board 6 using the cushion material 1 configured as described above will be described.

As shown in FIG. 3, two mirror plates 8, 8 made of stainless steel or the like are respectively disposed on the upper and lower sides of the printed circuit board 6, and furthermore, two mirror plates 8, 8 made of stainless steel or the like are arranged on the upper and lower sides of the upper mirror plate 8 and the lower surface of the lower mirror plate 8. 2 pieces of cushion material 1,
After arranging 1, they are pressurized in the vertical direction by a pair of press hot plates 9, 9 arranged above and below,
Air remaining between the laminated surfaces is removed, and heat treatment is performed to a predetermined temperature.

The printed circuit board 6 is molded by processing for a predetermined period of time while keeping the pressure and temperature constant. In this case, since the three types of reinforcing sheets 3, 4, and 5 are buried below the outer periphery of the cushion material 1, the pressing force at the center is higher, and air bubbles existing in the printed circuit board 6 are The bubbles move from the center where the pressure is high to the outer periphery where the pressure is low, and only the bubbles are vented to the atmosphere.

At the same time, the printed circuit board 6 is bonded without any gaps.

On the other hand, since the pressure applied to the outer periphery of the cushion material 1 is lower than that at the center, the adhesive from the printed circuit board 6 is actively prevented from flowing out.
is formed to be flat and of uniform thickness.

After a predetermined period of time has elapsed, by stopping the pressurization and heating and performing a cooling process, the mirror plates 8, 8 and the press hot plates 9, 9 are separated from the top and bottom of the printed circuit board 6, respectively, and the pressurization is performed. Pressure molding of the printed circuit board 6 is completed by removing the molded printed circuit board 6.

By embedding the three types of reinforcing sheets 3, 4, and 5 below the outer periphery of the cushion material 1, a higher pressing force can be applied at the center, and the pressure can be increased from the center to the outer periphery of the printed circuit board 6. The printed circuit board 6 can be adhered without any gaps while removing air bubbles between the adhesive surfaces, and high adhesive strength can be obtained.

In addition, the printed circuit board 6 can be formed to have a flat and uniform thickness, which reduces the occurrence of distortions and warps due to uneven thickness, and improves and stabilizes the quality. can be implemented reliably.

In the correspondence between the structure of this invention and the above-mentioned embodiment, the elastic material of this invention is
Similarly, the reinforcing material corresponds to each of the reinforcing sheets 3, 4, and 5, as well as the reinforcing rubber 13 and reinforcing sheet 14, which will be described later. It is not limited to only the configuration.

For example, in the above embodiment, each reinforcing sheet 3,
Although 4 and 5 are formed into square shapes, they may be formed into an appropriate shape such as a circle or a triangle to correspond to the circuit forming surface of the printed circuit board 6.

Further, the sheet main body 2 may be formed of an elastic material having high cushioning properties and a low elastic modulus, such as a soft synthetic resin.

(H) Other embodiments of the invention The drawing shows a cushion material whose entire sheet is made of silicone rubber, and as shown in FIG. In the center of the sheet body 12, a reinforcing rubber 13 having an elliptical vertical cross section, which is made of silicone rubber having a higher elastic modulus than the sheet body 12 and has a thicker center and a thinner outer circumference, is integrated. It is buried.

The above-mentioned sheet body 12 is made such that the total wall thickness with the reinforcing rubber 13 embedded therein is 1 mm to 3 mm.
The thickness of part A is 0.2mm to 0.9mm, the thickness of part B is 0.2mm to 0.6mm, and the thickness of part C is 0.3mm to 2mm.
It is formed in mm.

In the case of this configuration, the same effect as the above-mentioned embodiment can be obtained, and since the entire sheet is made of silicone rubber, it can be integrally molded using an extruder or the like (not shown). becomes easier.

Further, as shown in FIG. 5, a carbon fiber, aramid fiber, glass fiber, etc., which has a higher elastic modulus than the reinforcing rubber 13, is formed at the center in the thickness direction of the reinforcing rubber 13 embedded in the sheet main body 12. It is also possible to embed and mold a large-area reinforcing sheet 14.

[Brief explanation of the drawing]

The drawings show one embodiment of this invention; Fig. 1 is an enlarged longitudinal cross-sectional view of the central part of a cushion material with a reinforcing sheet embedded therein, Fig. 2 is an enlarged plan view showing the area ratio of the reinforcing sheet, and Fig. 3 is a printed image. FIG. 4 is a side view showing the pressurized state of the substrate; FIG. 4 is an enlarged longitudinal cross-sectional side view of the central part of a cushion material in which reinforcing rubber is embedded, showing another embodiment;
FIG. 5 is an enlarged vertical cross-sectional side view of the central portion of a cushion material in which a reinforcing sheet is embedded in the central portion of reinforcing rubber. 1, 11... Cushion material, 2, 12... Sheet body, 3, 4, 5, 14... Reinforcement sheet, 6...
...Printed circuit board, 13...Reinforcement rubber.

Claims (1)

[Claims for Utility Model Registration] A cushion material used in pressure molding of printed circuit boards, wherein the cushion material is made of an elastic material, and a reinforcing material having a higher elastic modulus than the elastic material is provided in the center of the cushion material. Cushion material with buried.