JPH09199856A - Manufacture of printed wiring board provided with cavity for mounting semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a compression pressure to be uniformly transmitted through a laminate by a method wherein a printed wiring board, an adhesive sheet, a printed wiring board having a cavity for mounting a semiconductor device, and a cushioning material composed of two thermoplastic resin films and a prepreg sandwiched in between them are successively laminated and thermocompressed. SOLUTION: A printed wiring board 1 which is not subjected to boring, a prepreg subjected to boring, a printed wiring board 2 provided with a hole used for a cavity, a prepreg subjected to boring, and a printed wiring board 2 provided with a hole used for a cavity are piled up in this sequence aligning the traies provided to them with each other. A cushioning material 7 composed of two trifluoropolyethylene resin films 5 and a prepreg 6 sandwiched in between them is provided onto the printed wiring board 2 subjected to boring, and all the laminate is sandwiched between two mirror plates and thermocompressed. Heat is transmitted sooner to the prepreg 6 included in the cushioning material 7 than to the wiring board body, and resin contained in the adhesive sheet 4 is fused to fill up a cavity 3. Therefore, a pressing pressure can be uniformly transmitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board with a cavity for mounting a semiconductor element.

[0002]

2. Description of the Related Art A printed wiring board with a cavity for mounting a semiconductor element has a printed wiring board 1 serving as a base and a printed wiring board 2 having a cavity 3 serving as a cavity portion for mounting a semiconductor element bonded and integrated. Being manufactured (Fig. 2
reference). Usually, the semiconductor element mounting cavity portion is provided with terminals for electrically connecting the mounted semiconductor element and the printed circuit. Therefore, in order to prevent the resin from flowing out to this portion, an adhesive sheet 4 with a small resin flow such as a no-flow prepreg or a bonding sheet is used for the adhesive integration, and the adhesive sheet 4 is inserted between the printed wiring boards and heated. Adhesion is integrated by pressing.

[0003]

However, in the heating and pressurizing step, the pressure is not transmitted to the cavity 3 which becomes the cavity for mounting the semiconductor element, and conversely the pressure is locally applied around the cavity 3. The resin may flow out into the space 3 due to the addition of the resin. An object of the present invention is to solve such a problem.

[0004]

According to the present invention, a printed wiring board 1 serving as a base, an adhesive sheet 4, a printed wiring board 2 having a cavity 3 serving as a cavity for mounting a semiconductor element, and two thermoplastic resin films are provided. Prepreg 6 between 5 and 5
Is a method for manufacturing a printed wiring board with a cavity for mounting a semiconductor element, which is characterized in that the cushioning material 7 on which is arranged is stacked in this order and heated and pressed (see FIG. 1).

After the completion of heating and pressing, the cushion material 7 is peeled off. The prepreg 6 of the cushion material 7 is the same as the adhesive sheet 4 or the resin viscosity of the adhesive sheet 4 at the time of heating is in the range of the resin viscosity of the adhesive sheet 4 (the resin viscosity of the adhesive sheet 4 minus 50 Pa · s). And the most preferable result is obtained.

Heat is transmitted to the prepreg 6 of the cushion material 7 before the wiring board main body, and as a result, the resin of the adhesive sheet 4 is melted and fluidized to fill the voids 3 before being fluidized. Then, the resin of the adhesive sheet 4 between the printed wiring boards used for adhesive integration is flowed later than this, so that the resin filled in the voids 3 uniformly transmits the pressing pressure. Therefore, the product is pressed with a uniform pressure over the entire surface,
Further, it is possible to prevent the resin from flowing in from the adhesive sheet 4.
The resin of the prepreg 6 of the cushion material 7 can be easily peeled off by the thermoplastic resin films 5 and 5 without adhering to the printed wiring board.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The thermoplastic resin films 5 and 5 are
It must be a heat resistant film. At least, the resin of the prepreg 6 of the cushion material 7 must not melt at a temperature at which the resin melts and flows. As such a heat resistant film, for example, a film of polyethylene trifluoride can be used. After the resin of the prepreg 6 of the cushion material 7 begins to harden and does not flow, it may be in a melt flow state. This is because, in this state, the flow of the thermoplastic resin melted by the resin of the prepreg 6 of the cushion material 7 is suppressed, and the film is formed again by cooling after the heating is completed.

[0008]

[Example] A printed wiring board as a base having a thickness of 0.2 mm and not having been drilled, an adhesive prepreg having a hole of 10 mm × 10 mm, and a hole for a cavity of 10 mm × 10 mm having a thickness of 0.2 mm Processed printed wiring board, adhesive prepreg with 15 mm x 15 mm holes, 15 mm x 0.2 mm thick
A printed wiring board with a 15 mm cavity hole is laminated in this order and with the holes aligned, and further, between the two trifluorinated polyethylene resin films on the printed wiring board with a hole. A cushioning material sandwiching a prepreg (the same material as the above-mentioned adhesive prepreg) was arranged, and these were sandwiched between two end plates, and heated and pressed at a pressure of 3 MPa and a temperature of 170 ° C. for 90 minutes. As the prepreg, a prepreg GEA-67N (trade name of Hitachi Chemical Co., Ltd.) having a substrate thickness of 0.05 mm, a resin content of 65%, and a resin viscosity of 750 Pa · s was used. The obtained wiring board had a small variation in board thickness and was excellent in that resin did not flow into the cavity.

Comparative Example A wiring board was obtained under the same structure and conditions as those of the example except that the cushion material was not used. The obtained wiring board had large variation in board thickness, resin flowed out to the cavity, and mounting of semiconductor elements and wire bonding were impossible.

[0010]

The heat is transmitted to the prepreg 6 of the cushion material 7 before the main body of the wiring board, and as a result, the adhesive sheet 4 is formed.
Before the resin of No. 3 melts and flows, the resin melts and flows to fill the void 3. Then, the resin of the adhesive sheet 4 between the printed wiring boards to be bonded and integrated flows later than this, so that the resin filled in the voids 3 uniformly transmits the pressing pressure. Therefore, the entire surface of the product is pressed with a uniform pressure, and the resin can be prevented from flowing from the adhesive sheet 4.

[Brief description of drawings]

FIG. 1 is a schematic side view for explaining a method of the present invention according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an example of a printed wiring board manufactured by the method of the present invention.

[Explanation of symbols]

 1 Printed Wiring Board as Base 2 Printed Wiring Board with Voids 3 Voids as Cavities for Mounting Semiconductor Devices 4 Adhesive Sheet 5 Thermoplastic Resin Film 6 Prepreg 7 Cushion Material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Sakai 1500 Ogawa, Shimodate City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Shimodate Factory

Claims (2)

[Claims] 1. A printed wiring board serving as a base, an adhesive sheet, a printed wiring board having a cavity serving as a cavity for mounting a semiconductor element, and a cushioning material in which a prepreg is arranged between two thermoplastic resin films in this order. A method for manufacturing a printed wiring board with a cavity for mounting a semiconductor element, which comprises stacking, heating and pressing. 2. The resin viscosity of the prepreg for cushioning material is the same as that of the adhesive sheet 4 at the heating temperature, or the resin viscosity of the prepreg at the time of melting is the same as the resin viscosity of the adhesive sheet 4 (the resin viscosity of the adhesive sheet minus 50 Pa.・ S)
The method for manufacturing a wiring board with a cavity for mounting a semiconductor device according to claim 1, wherein the wiring board has a cavity.