JPH03185787A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To simplify the process, heighten the accuracy of a circuit, and steeply increase the quantity of a current which can be conducted by depositing a film with a metal mask and plating the deposited film to thicken conductive sections. CONSTITUTION:A circuit is formed by depositing a deposition material on the surface of the base material of a printed wiring board through a metal mask. The deposition material is made of a metal or metallic oxide and deposited by vacuum deposition, sputtering, or other methods to a thickness of 1.0X10<-2>-10mum. The conductive sections of the circuit are formed by deposition and then thickened by plating with a conductive material. The quantity of a current which can be conducted through the circuit can steeply be increased by thus forming the thick-film sections.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a printed wiring board, in which a vapor-deposited portion of a circuit pattern formed by a vapor phase method is thickened.

(Prior art and its problems) Printed wiring boards are used in computers, audio equipment, video equipment, automobile electrical equipment, telephone exchanges, word processors, facsimile machines, laser disc players, cameras,
It is used for various purposes such as electronic watches, but it has become smaller and
In order to improve performance, high-density, high-precision printed wiring boards are desired.

Conventionally, printed wiring boards have been made by pasting a conductive metal plate onto a substrate material, coating or pasting a photoresist on it, exposing it to light through a photomask and developing it, or exposing the resist to laser light. Usually, a pattern is formed by irradiation and direct drawing, and then a circuit is formed by etching.

However, these methods, which require a resist and etching process, have the following problems: (1) The process is complicated;
The etching solution easily invades and erodes the interface between the conductive metal plate and the photoresist film, and the accuracy of the circuit obtained is poor because the thick metal plate is etched. There are problems such as large losses in terms of resources as the liquid is discarded, and (2) waste liquid treatment of developer and etching liquid is required.

In order to solve these problems, a method has been proposed in which a circuit is formed by depositing a deposition substance onto a base material through a metal mask having through holes corresponding to the circuit pattern. However, although this method can solve the above problem, since the conductive part of the circuit formed by vapor deposition is a thin film, the amount of electricity that can be conducted is small, and the application is greatly limited.

(Means for Solving the Problems) The present inventors have solved the above-mentioned problems of (1) to (3) in methods requiring resist and etching steps, and moreover, a circuit formed by vapor deposition through a metal mask. As a result of intensive research into the manufacturing method of printed wiring boards, which is not severely limited in application, we have found that all of the above problems can be solved by thickening the circuit formed by vapor deposition by plating. Heading This invention has been achieved.

That is, in the present invention, a vapor deposition substance is deposited on the surface of a printed wiring board substrate by a vapor phase method through a metal mask having through holes corresponding to a circuit pattern, to a thickness of 1.0×10−.
``After forming a circuit having a conductive part of P to 10P, plate the conductive part with a conductive material so that the thickness of the conductive part after plating is at least twice the thickness before plating. The present invention provides a method for manufacturing a printed wiring board characterized by forming it into a film.

In the method of the present invention, a circuit is first formed by depositing a vapor deposition substance on the surface of a printed wiring board substrate through a metal mask.

Examples of the base material include organic materials such as polyimide, polyether polyimide, polyamide polyimide, and polyethylene terecrate, ceramics, and silicon.

Examples of the vapor deposition substance to be vapor-deposited on the surface of this base material through a metal mask include metals and metal oxides, and specific examples include copper, nickel, silver, gold, chromium, tin, aluminum, and the like. Examples include alloys and tin oxide. These evaporation substances are deposited using vacuum evaporation, sputtering, ion blating, electron cyclotron resonance, etc., so that the film thickness is 1.0×10-”F to 10P, preferably about 0.1 to 3 mm. , film thickness is 1
．． If it is thinner than 0xlO-''P, it is not preferable because the defect rate of the deposited film increases due to variations such as unplated areas remaining.

On the other hand, if the film thickness exceeds the IOF, it would take a long time to deposit the film to this thickness, making it impractical. In addition, when performing vapor deposition, two or more types of vapor deposition substances may be simultaneously vapor-deposited to form a mixed film of two or more metals, or after vapor-depositing one vapor-deposition substance, another vapor-deposition substance may be vapor-deposited to form a multilayer film. A vapor deposited film will be formed.

The metal mask used in the method of the present invention is a metal plate having through holes corresponding to the shape of the intended circuit pattern, and during vapor deposition, the deposition substance is deposited on the surface of the base material through the through holes, and the material is deposited on the surface of the base material through the through holes. Since metal is not deposited on the surface of the base material due to shielding, a deposited film having a circuit pattern corresponding to the shape of the through hole can be formed. Materials for metal masks include steel, nickel, silver, gold, aluminum, and alloys of these metals. Among these, nickel has magnetism, so it cannot be used with a magnet or the like from the back side of the printed wiring board substrate. The thickness of the metal mask is preferably about 10 mm because it can be brought into close contact with the surface of the base material by applying magnetic force and is resistant to rust.
The range is preferably from pm to about 500P, and more preferably from 30 to 200P. Metal masks are made by forming a circuit pattern on a metal plate by directly drawing on the metal plate with a laser, curing resist through screen printing or pattern film, and developing it.
It is created by etching with a chemical solution, or by an additive method in which a resist layer with a circuit pattern is formed on a base film, a circuit is formed by plating the recesses, and then the remaining resist layer and base film are removed. be able to.

In the method of the present invention, after forming the conductive part of the circuit by vapor deposition, the conductive part is plated with a conductive material to thicken the conductive part. After vapor deposition, the metal mask can be removed and the plating process can then proceed.

Conductive materials to be plated on conductive parts include copper, nickel, gold, silver, chromium, tin, zinc, etc., and can be electroless plated using conventionally known plating bath compositions and plating methods.
Plating can be performed by any electrolytic plating method. In forming the plating layer, the conductive material to be plated on the conductive portion may be the same kind of material as the deposited film or a different kind of material, or two or more kinds of materials may be plated in a multilayer.

In the method of the present invention, the conductive part of the circuit obtained by vapor deposition serves as a seed for the next step, plating, and the thickness of the conductive part after plating is equal to that of the vapor deposited film, which is the conductive part before plating. It is necessary to plate the plate so that it is at least twice the thickness, preferably 5 to 100 times the thickness. By ensuring a film thickness thicker than the vapor-deposited film through plating, the amount of electricity that can be conducted through the circuit can be greatly increased.The plating thickness can be selected as appropriate depending on the application, but usually, It is preferable to apply plating to a thickness of about IJffil to about 100P.If the thickness of the conductive part after plating is less than twice the thickness of the conductive part before plating, the amount of electricity that can be conducted by plating will not increase much and the plating will not be possible. There is a problem that the effect is not sufficient.

(Effect of the invention) The method of the present invention performs vapor deposition using a metal mask.

Since the conductive parts are made thicker by plating the deposited film, the process is simpler, the circuit precision is higher, and the etching process saves resources compared to the conventional method that requires a resist and etching process. It has the advantage that there is no loss and there is no need to treat waste liquids such as developer and etching liquid. Further, in the printed cotton distribution board obtained by the method of the present invention, the amount of electricity that can be conducted can be greatly increased by thickening the conductive portion by plating, so that there are no restrictions on the use due to the amount of electricity. In addition, if protection of the conductive parts of the circuit, prevention of oxidation, ease of bonding, etc. are required, the above objectives can be achieved at the same time as thickening the film by plating with a conductive material suitable for the purpose. .

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A metal mask was placed on the surface of a polyimide substrate with a thickness of 50 JIM, and copper was deposited to a width of 1 mm and a length of 100 mm using a vacuum evaporation method.
, a circuit pattern was created by vapor deposition to a thickness of 0.1 m. Next, the metal mask was removed, and the board with the circuit pattern was immersed in a copper electroless plating solution for 4 hours, and a 2-thick layer was deposited on the copper film.
A circuit was obtained by forming 0 copper layers. In the resulting circuit a current of 5
When 00 mA was applied, the resistance was 8.6 x 10-''Ω and the heat flow was 2.15 x I0-2W.

Furthermore, when a current of 500 mA is passed through a circuit with copper deposited before plating, the resistance is 8.7 Ω and the heat flow is 2.17 W.
Met.

Example 2 A circuit pattern was created by covering a polyethylene terephthalate (PET) substrate with a thickness of 70p with a metal mask and depositing copper in a vapor phase to a width of 1 mm, a length of 100 mm, and a thickness of 0.5P using a sputtering method. Then, the metal mask was removed, and the substrate having the circuit pattern was immersed in a nickel plating solution, and electrolytic plating was performed to form a nickel layer with a thickness of 20 mm on the copper film. Next, gold was deposited on the nickel layer to a thickness of one layer by electrolytic plating to obtain a circuit.

A current of 1. When OOOmA was applied, the resistance was 0.29Ω and the heat flow was 0.29W. Note that a current of 1. OOOmA
When flowing, the resistance was 3.5Ω, and the heat flow was 3.5W.
Met.

Example 3 An alumina substrate with a thickness of 500- is covered with a metal mask, and nickel is coated with a width of 1 mm and a length of 1 mm using an electron cyclotron resonance method.
A circuit pattern was created by vapor deposition to a thickness of 00 mm and a thickness of tP. The metal mask was removed, and a two-layer thick silver layer was formed on the nickel film of the circuit patterned substrate by electroless plating to obtain a circuit.

When a current of 300 mA was passed through the resulting circuit, the resistance was 7.
．． 3XIO-' Ω, and the heat flow was 6.6 x 10-' W. When a current of 300 mA was passed through the nickel-deposited circuit before plating, the resistance was 7.2 Ω.
The heat flow was 6.5XlO-'W.

Claims (1)

[Claims] 1. A vapor deposition substance is deposited on the surface of the printed wiring board substrate by a vapor phase method through a metal mask having through-holes corresponding to the circuit pattern to a thickness of 1.0 x 10^-^2 μm to 1 μm.
After forming a circuit having a conductive part of 0 μm, the conductive part is plated with a conductive material so that the thickness of the conductive part after plating is at least twice the thickness before plating. A method for manufacturing a printed wiring board, characterized by: