JP3975371B2 - Wiring board manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a wiring board, and more particularly to a method for manufacturing a wiring board for a semiconductor package.
[0002]
[Prior art]
Along with the downsizing of electronic devices, there is an increasing demand for further downsizing of semiconductor packages. In order to cope with this downsizing, a so-called chip size package (hereinafter referred to as CSP) that is approximately the same size as a semiconductor chip has been proposed. This is a package having a connection portion with an external wiring board in the mounting region, not in the peripheral portion of the semiconductor chip.
[0003]
As a specific example, a polyimide film with bumps is bonded to the surface of a semiconductor chip, electrical connection is made between the chip and a gold lead wire, and then epoxy resin or the like is potted to seal the magazine “NIKKEI MATERIALS & It is known from P18-19 of TECHNOLOGY 94.4, No. 140 ", and forming a metal bump on the temporary substrate at a position corresponding to the connection portion between the semiconductor chip and the external wiring board, and bonding the semiconductor chip face down, It is known by the paper “Smallest Flip-Chip-Like Package CSP” (The Second VLSI Packaging Workshop of Japan, P46-50, 1994).
[0004]
[Problems to be solved by the invention]
Among various proposed CSPs, a CSP based on a polyimide film is expected to achieve both reliability and cost. However, when a polyimide film substrate with a holed adhesive and copper foil is laminated and integrated by pressing and heating in a large size, a gap occurs between the copper foil and the adhesive, and the base substrate adheres within the hole. There is a problem that the agent is exposed and the connection area of the solder ball formed in the hole is reduced.
[0005]
An object of this invention is to provide the manufacturing method of the wiring board for semiconductor packages excellent in suppression of the shift | offset | difference between copper foil and an adhesive agent, and excellent in reliability and economical efficiency.
[0006]
[Means for Solving the Problems]
The method for producing a wiring board according to the present invention comprises a flexible base material coated with a B-stage adhesive on at least one side and a copper foil layered so that the adhesive is in contact with the copper foil. In a method for manufacturing a wiring board having a process of stacking and integrating a cushioning material on the back surface of a base material and pressurizing and heating, dummy holes are formed in the flexible base material.
[0007]
As the flexible substrate 2, a plastic film made of polyimide resin, epoxy resin, or the like is suitable. In addition, a material obtained by impregnating a substrate such as glass nonwoven fabric with polyimide resin or epoxy resin and heat-curing it can be used.
[0008]
As the adhesive 1, a polyimide resin or an epoxy resin can be used, and it is applied on a substrate by gap coating, curtain coating, printing method, or the like, and is heated and cured to be a semi-cured state (B stage).
[0009]
Next, a dummy hole can be formed by drilling, punching, or laser processing, and the hole preferably has a diameter of 1.0 mm or more. When the hole diameter is less than 1.0 mm, the effect of suppressing the displacement between the copper foil and the adhesive is small.
Further, it is preferable that the hole is formed as much as possible outside the product to be a semiconductor package.
[0010]
As the cushion material 8, a film of Teflon, polyimide, vinylidene fluoride, or the like can be used.
[0011]
(Function)
In the present invention, the cushion material is deformed and enters the dummy by the dummy hole, and the displacement of the base material is suppressed.
[0012]
【Example】
Example 1
1) As flexible substrate 2, Upilex S (trade name) manufactured by Ube Industries, Ltd., which is a polyimide film with a thickness of 50 μm, and N4 adhesive (Hitachi Chemical Industry Co., Ltd.), which is a polyimide adhesive, as adhesive 1 (Product name, product name) is applied about 10 μm, dried at 180 ° C. for 130 minutes to form a B stage, cut into a 500 mm square, and a 0.4 mm diameter hole for solder ball bonding is drilled in the wiring area. Opened.
2) As shown in FIG. 3, a hole 11 having a diameter of 1.5 mm was drilled outside the wiring area.
3) As a cushion material, UL900 (trade name, manufactured by Nitto Denki Kogyo Co., Ltd.), which is a Teflon film having a thickness of 80 μm, was cut into 250 mm square.
4) After arranging four 250 mm square Teflon films of the cushioning material 8 prepared in the above process on a stainless steel plate having a thickness of 1.5 mm as the end plate 9, the flexible base material 2 having the holes punched thereon is stacked. Further, SLP-18 (trade name, manufactured by Nippon Electrolytic Co., Ltd.), which is a copper foil having a thickness of 18 μm, is stacked, and a stainless steel plate having a thickness of 1.5 mm is stacked as the end plate 9, and 30 kgf / cm ² at 250 ° C. Under these conditions, the layers were integrated by pressing and heating for 60 minutes.
5) After laminating Photec H-W425 (trade name, manufactured by Hitachi Chemical Co., Ltd.), a dry film for etching having a thickness of 25 μm, at 100 ° C. under conditions of 4 kgf / cm ² and a laminating speed of 1.5 m / min. , Exposed to light through a photomask at 80 mJ / cm ² , developed, formed an etching resist, and selectively etched away portions not covered with the etching resist with a ferric chloride etching solution The resist was removed to form a wiring pattern.
6) Next, electroless nickel plating with a thickness of 5 μm and electroless gold plating with a thickness of 0.4 μm were performed.
[0013]
Example 2
1) The same process as (1) of Example 1 is performed.
2) A hole with a diameter of 3.0 mm is punched outside the wiring area.
3) The same steps as (3) to (6) of Example 1 are performed.
[0014]
Comparative Example 1) The same steps as (1) and (3) to (6) of Example 1 are performed.
[0015]
The maximum deviation amount of Examples 1 and 2 of the present invention was 20 μm. On the other hand, in the case of the comparative example, the maximum shift amount was 90 μm, and the effect of suppressing the shift between the copper foil and the adhesive according to the present invention was recognized.
[0016]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a method for manufacturing a wiring board for a semiconductor package, which is excellent in suppressing a deviation between a copper foil and an adhesive, and excellent in reliability and economy.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view in each step showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing an embodiment of the present invention.
FIG. 3 is a top view showing an embodiment of the present invention.
[Explanation of symbols]
1. Adhesive 2. 3. Flexible base material Hole 6. Copper foil7. Wiring pattern 8. Cushion material9. End plate 11. Dummy hole

Claims (1)

At least on one side, a flexible base material coated with a B-stage adhesive is perforated and a copper foil is stacked so that the adhesive contacts the copper foil, and a cushion material is stacked on the back surface of the flexible base material, A method for manufacturing a wiring board, comprising: forming a dummy hole in a flexible base material in a method for manufacturing a wiring board having a step of pressurizing and heating and integrating the layers.

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