JPS5878493A - 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] This invention relates to a printed wiring board manufactured using a novel fully additive method, and further relates to a printed wiring board that is inexpensive to manufacture, has good heat dissipation, and can be mounted at high density. .

Conventionally, various materials have been used for printed wiring boards, and there are many different manufacturing methods. The current mainstream method is the sub-F lactip method, in which a circuit pattern is formed by etching a substrate made of a glass eloxy laminate or a paper phenol plate covered with steel foil.

However, this method requires high accuracy because the pattern accuracy is limited by the problem of undercutting in the etching pattern, poor heat dissipation due to the substrate material with low thermal conductivity, and the thickness of the etching foil and resist film. In addition to serious performance problems such as the inability to perform high-density wiring, there are also problems in that the manufacturing process is long and the cost is high because a resist material such as a dry film is used.

As a method to improve these drawbacks, an additive method is being considered in which electroless plating is selectively applied only to predetermined pattern portions of the substrate. Several additive processes have been announced and put into practical use, such as the 00-4 method, the P-1 method, the Photofor-5 method, and the P8MI) method.

According to these methods, there is no undercut F, high-density wiring is possible, and the cost is low. Some of the advantages of the Adifip process, such as excellent mass productivity, can be satisfied. However, no matter what additive methods are currently being considered, the heat dissipation problems associated with high-density packaging cannot be solved. In addition, the true flow additive method has the disadvantage that poor twin precision due to plating fog and poor pattern adhesion remain as major gaps, resulting in poor manufacturing yield and ultimately not leading to cost reduction.

The present invention improves these drawbacks, and provides a printed wiring board that satisfies all of the above-mentioned advantages inherent in the additive method, has excellent heat dissipation properties, and has a wide range of applications.

The present invention will be described in detail in the order of manufacturing steps. First, metal is used as the substrate material. What is the material of the metal?In general, it is a sheet of α1~10cm thick such as steel or aluminum.
Alternatively, 7-ply material is suitable.

These metal sheets or hoops are first punched into large dimensions. Punch out through holes, guide holes, TO size, and other necessary parts. The first feature of the present invention is that the surface of these metal materials is electrodeposited for insulation treatment. Titanium oxide, zinc oxide, tin oxide, and indium oxide.

Almonium oxide, tantalum oxide, zirconium oxide,
*The method consists in dispersing %-type semiconductor powder such as niobium oxide whose surface has reducing properties by irradiating it with ultraviolet rays and precipitating it simultaneously with the resin. It has been known for a long time that these oxides have a reducing ability when the surface of these oxides is depleted of oxygen by light irradiation. Titanium oxide is particularly suitable for this method because it has strong reducing properties.

In general electroless plating, a sensitizing step is required to adsorb divalent tin ions in order to reduce and precipitate fine metal particles that serve as plating nuclei, but the present invention does not require a sensitizing step. In addition, since only the irradiated area has reducibility, the desired pattern can be obtained by exposing through a mask, and the steps of 7e) rolling, curing, and peeling of the resist are unnecessary, and there is no thickness of the resist film. High-density patterns can be formed without defects such as undercuts and overhangs. As a result of experiments, it was found that the smaller the particle size of the exposed semiconductor powder and the larger the volume ratio in the coating film, the greater the effect. It is preferable to prepare an electrodeposition paint that contains powder with a particle size of 1 μm or less by volume of 20 or more in the solid content of the paint.The matrix resin of the electrodeposition paint is an anionic butadiene-based resin and a cationic epoxy resin. Polybutadiene, which is flexible, is suitable for flexible substrates, and polybutadiene, which is hard and has good moisture resistance, is suitable for rigid substrates. Both require a thickness of sOμ or more to ensure insulation and reduce the amount of floating springs, and the electrodeposition voltage is 1
Requires 50v or more. In addition, general O electrodeposition paints have the disadvantage that when heated and cured after electrodeposition, the paint flows especially at the edges of the substrate, resulting in thin film thickness and poor insulation, but as in the present invention, a large amount of oxide wheel Electrodeposition liquid dispersed in the electrode layer prevents the paint from flowing around the edges, improving the reliability of the insulation.

Next, the process of selectively electroless plating the substrate, which has had the surface of the metal core insulated, using light irradiation, begins. First, in order to ensure adhesion of the plating, the surface of the electrodeposited coating is roughened by etching with a common Coumu sulfuric acid mixture. Bee envy strength”L 5
To obtain about kg/as, 50℃, 2 minutes I!
A degree of etching is sufficient.

Etching, washing, drying 11. Expose to ultraviolet light through a glass or quartz mask. In the case of titanium oxide, the wavelength of light necessary for a reducing reaction is 400 mm or less, but in order to shorten the exposure time, it is preferable to expose with a light source that includes a wavelength of 2 So-300 mm (). In this case, quartz glass is required for the mask. After exposure, normal activation is performed to precipitate fine metal particles that will become plating nuclei in the exposed area. A dilute aqueous solution of palladium chloride is suitable for the activator. Thereafter, a conductor pattern is formed by electroless steel plating or nickel plating, and if necessary, thick electrolytic steel plating or gold plating for bonding is applied to complete the printed wiring board.

Comparing the characteristics of printed wiring boards made using the above processes with the conventional subtractive and additive methods, we can summarize the following: (1) The board material is inexpensive, and it is easy to use for large punching and pressing. Since machining is easy and the patterning process is short, manufacturing cost F can be significantly reduced.

(2) Optical selective plating without etching eliminates defects such as undercuts and overhangs.

(1) Since no resist is used, the O
Fine patterns are possible.

(4) The metal core has good heat dissipation and is suitable for high-density packaging. (5) It is suitable for both continuous mass production using 7-ply material and low-volume multi-product production using sheet material.

Therefore, the reliability of the through hole is also high.

By combining the metal core, electrodeposition with S-type semiconductor powder dispersed therein, and photo-selective plating, it is possible to manufacture a printed wiring board with a wide range of applications, which has low heat flux and excellent quality. Next, a typical example will be described.

<Example> A printed wiring board for a wristwatch was manufactured in an integrated manner using a hoop material as a base material. Thickness (L 15■ steel ((L 8%)
0ff) km through hole, IO hole, 4
Holes are punched out, and electrodeposited on the entire surface after degreasing and cleaning.
Did. The Ik material resin was a 720% cationic resin, and the paint was prepared so that 25 capacitance arcs of the am component in the electrolytic film were titanium oxide. Titanium oxide is grain @a2~r1
5μ powder made from anatase was used. 2501 at 20℃
After electrodeposition for 5 minutes, it was washed with water and baked at 180° C. for 30 minutes to harden it.

The film thickness is approximately 50μ on the flat part, and SO ~ 35μ on the edge part.
40°C in a mixture of 0-order saturated tetramuic acid and sulfuric acid at lK,
The surface was roughened by etching for 2 minutes. The zero step difference on the rough surface was approximately 3μ and uniform. After washing with water, neutralizing, and drying, it was irradiated with ultraviolet rays at a wavelength of about 250 for 2 seconds using an exposure machine. The mask was made of quartz and was in contact with the substrate. Immediately after exposure, it was immersed in a 1-water droplet solution of palladium chloride at 20°C for 2 minutes, and after being lightly washed with water, it was plated in an electroless nickel plating solution at 50°C for 5 minutes. A nickel plating pattern was obtained only in the ultraviolet irradiated area. The minimum line width and line spacing of the pattern were both 50 μm, and defects such as wire breaks and leaks were 1- or less. The wiring board was completed by directly electrolytically plating 05μ gold on the Kel pattern. Good results were obtained in the environmental resistance test after bonding and mounting. Furthermore, the manufacturing cost of the wiring board can be significantly reduced to about 1/2 compared to the subtractive method in which a conventional copper-clad Gala Evo board is patterned in 7 steps.

that's all Procedural amendment (voluntary) November 8, 1982 Commissioner of the Patent Office 1981 Patent Application No. 177489 2. Name of the invention Print distribution pole 3. Person who makes corrections Visit [8th role Tsuneya Nakamura 4. Agent Procedural amendment 1. Specification: 5 members, 6 lines ``It is mass production''. Corrected to ``uniplexity''.

2 Specification 41I line 6 (-Place the hole for TO "Correct IO hole J Kl'l, 5. Specification 6 lines from the bottom of page 7 "Minimum 2μ radius" stop Correct it to ``minimum 20μ blind''.

4. Specification page 8 line 15 ``Paint orange fat is 4v201!J stop. “The paint resin is corrected to N Y 20% J.

V. Statement line 9NS ``The wavelength is about 2501111J. [Corrected to wavelength 250-450 nmJ.

Melon specification 9 @ line 6, line 8 "Nickel" stop meeting [Corrected to copper 1.

1 Details page 419 line 7 ``Perform plating for 5 minutes,'' then stop. Correct it by saying, ``Plating was done for 1 hour.''

a Specification line 917 [50℃ in liquid, -1 toraru Correct it to ``25℃ in liquid.''

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Claims (1)

[Claims] Electrical insulation treatment is applied to the metal base material by electrodeposition coating,
In a printed wiring board on which a conductive pattern is formed, the surface has a reducing property when exposed to light such as titanium oxide, zinc oxide, tin oxide, indium oxide, aluminum oxide, tantalum oxide, zirconium oxide, etc. in the electrodeposition paint. The activator is selectively activated by dispersing the conductor powder and electrodepositing it simultaneously with the resin to form an insulating layer, and then irradiating light containing ultraviolet light only to the areas on the insulating coating where the conductor is needed. A printed wiring board characterized in that a conductor pattern is formed by reduction deposition and imparting selectivity to electroless plating.