JPS6092691A - Film base printed circuit board - 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] Industrial applications The present invention relates to a semiconductor element, a resistive element, and a capacitive element.

The present invention relates to the structure of a printed wiring board suitable for connecting chip components such as inductance elements by wire bonding technology.

Structures of conventional examples and their problems In the past, there have been some conventional examples of a state in which chip components are mounted on a printed wiring board, which is called chip-on-board technology. That is, as a first example, as shown in FIG. 1, after forming an electrical discharge processing layer 2 that creates a rough surface 3 on a polyimide film plate 1, a copper foil 6 is applied to the entire surface via a copper foil adhesive layer 4. The conductor portion 5 on which the copper foil is selectively etched is then plated with nickel 6 or gold 7,
There are wire-bonded aluminum wires. As a second example, as shown in FIG. 2, copper foil is directly adhered to the glass cloth base epoxy resin laminate 12, and then gold plating is applied to selectively etched portions of the copper foil. Conductor 1 having an uneven surface 14 having a wavy surface
3 was obtained, and 12-ear bonding of gold wire was made to this. The problem with these conventional examples is that in the first example,
Moisture is adsorbed or trapped in the alumite treated perforated parts, lowering the insulation properties of the board and causing electrical short circuits, bonding with gold wire and aluminum wire is difficult or troublesome, selective etching of copper foil, etc. The bath process during nickel plating is complicated and costly, and the residual ionic substances in the bath may contaminate the semiconductor chip and shorten its lifespan. In addition, in the second example, since the copper foil was directly adhered, the mesh of the glass fiber cloth in the laminate was replicated on the copper foil surface, causing unevenness and impeding the smooth operation of the wire bonding mechanism. Problems include the fact that the bathtub is contaminated and gold is expensive.

OBJECTS OF THE INVENTION The object of the present invention is to solve the drawbacks of the above-mentioned conventional examples and to obtain a simple and economical flexible wiring board for wire bonding.

Structure of the Invention As a structure of the present invention, firstly, a flexible insulating resin paste having good affinity with films such as polyester and polyimide is directly printed on an organic resin film.
forming a resin layer, secondly printing a highly insulating rigid resin paste selectively on the surface of the first resin layer to form a second resin layer, and thirdly selectively printing a surface of the second resin layer. The resin paste containing conductive particles is selectively printed within a range that does not protrude. Printing technology is used to form each resin layer, so that the required printing thickness is 10 to 150 microns ± 2. ~
This is to maintain a high precision of 6 microns. In addition, for printing the second and third resin layers, Messier screen plate making technology is effective in order to keep the width tolerance within 0.01 to 0.1 mm not only in the thickness direction but also in the horizontal direction. It is. Note that the configuration of the present invention includes the first. Second. After printing each third resin layer and preheating at 60-80℃, 120-220℃
A process of curing by heating in the air at a temperature of °C is involved.

DESCRIPTION OF EMBODIMENTS FIGS. 3 and 4 are plan views of various parts of an embodiment of the present invention. First, dirt, dust, etc., on the polyimide plate 22 with a thickness of 60 microns and a size of 50×50 are wiped off with an acetone solution.

This aluminum plate 22 is coated with an epoxy resin (for example, Shell Oil Company's product name 828) as a first resin layer.
) to which 70 phr of aromatic amine adduct resin (manufactured by Nippon Gosei Kako Co., Ltd., H-84) was added and the viscosity was 360 poise. The sample was printed on the entire surface and cured in the air at 130°C for 30 minutes. This first resin layer 23 has a thickness of 14±1 μm, a pencil hardness of 4H or more, and has the flexibility to withstand bending when a round bar with a diameter of O, SWm is sandwiched between the films, and has adhesive strength as well. 120
As high as 2 Kp/mtA at ℃.

As the second resin layer 24, an epoxy resin (Shell Oil Company 8
Using a solvent-free resin paste with a viscosity of 1100 poise to which 60 phr of aromatic amine adduct resin (ihonsei Kajo gH-so) was added to 28), 1 of Tetron was added.
Selective resist film on 60mesh screen with thickness 6o±
The first resin layer was selectively printed to a thickness of 36±2μ using a layer formed to have a thickness of 2μ, and then printed at 150°C.
Cure in air for 80 minutes. The second resin layer 24 has a thickness of 24±2μ, a pencil hardness of 6H or more, and a glass transition temperature TG of 180°C, but can withstand a deviation of about 101rrIn at the center of the film plate. It has flexibility.

The average size of the flaky silver powder as the third resin layer 25 is 1 to
Using a mixer, mix a resin paste containing 86% epoxy resin (1001 manufactured by Shell Oil Co., Ltd.) and 80 phr of modified acid anhydride (H-106 manufactured by Nippon Gosei Kako Co., Ltd.) as a hardening agent, based on a weight ratio of 5μ. Using a conductive resin paste with a viscosity of 150 poise,
0 mesh screen with selected resist film thickness 26±2
Using the material formed in μ, selective printing was performed to a thickness of 19±2 μ and cured at 150° C. for 60 minutes in the air.

The third resin layer 26 has a thickness of 14±2 μm, a pencil hardness of 8H or more, a glass transition temperature TG of 210° C., and a conductor resistance value of 10 mΩ/mouth.

Second. The increase in the hardness of the third resin layer is achieved by using a commercially available wire bonding device for semiconductor ICs, which is considered to be effective in preventing the dissipation of ultrasonic energy.The thin gold wire 26 and The aluminum thin wire 28 was bonded and a strength test was conducted, and the results are shown in the following table.

A practical standard of 6g or more can be obtained.

Note that if the surface of the conductive resin layer 26 is scraped and flattened, the bonding properties will be further improved.

At the same time, tin-lead containing 2% silver (61/37)
The adhesion of the semiconductor chip 31 with the solder 30 is 220~2
This can be done by processing at 80°C for a few seconds.

Effects of the Invention According to the present invention, sufficient adhesive strength can be obtained without performing special processing such as electric discharge machining on the surface of the polyimide film, thereby eliminating the possibility of water adsorption and trapping that is characteristic of polyimide films. It is possible to bond gold wire and aluminum wire together, the conductor can be formed in a dry process, and the manufactured product 4: (Higo A) is economical and at the same time is free from residual etching solution and plating solution. This avoids the problems of contamination of the mounted semiconductor chip and deterioration of its life characteristics.Also, the surface of the conductive resin layer is flat and mirror polishing is possible.It avoids expensive gold plating baths and is built into the conductive resin. It is possible to bond silver to gold.

As described above, the printed wiring board according to the present invention has a film base with high moisture resistance, conductors can be directly printed instead of etched, and can be formed using the dryer method, making wire bonding of surface mount devices possible, which is technically and economically advantageous. It is excellent.

[Brief explanation of drawings]

FIGS. 1 and 2 are sectional views of a conventional example, and FIGS. 3 and 4 are sectional views of each embodiment of the present invention. 22... Aluminum plate, 23... Insulating resin first layer, 24... Insulating resin second layer,
26... Conductive third layer.

Claims (1)

[Claims] A flexible first resin layer formed by printing an insulating resin paste on an organic film plate, a non-flexible second resin layer formed by printing and selectively overlapping an insulating resin paste, and the second resin. A third resin layer is provided by printing a conductive resin in an area that does not protrude from the same area as the third resin layer, and a gold wire or aluminum wire for connecting the electrodes of the semiconductor chip is provided to the top layer of the three resin layer constituent parts. A film-based printed wiring board characterized by thermocompression bonding of wires.