JPS62186588A - Manufacture of noble metal plated 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 [Field of Industrial Application] The present invention relates to a method of manufacturing a substrate for a hybrid integrated circuit, and more particularly to a method of manufacturing a circuit board on which a circuit is formed by plating a noble metal.

[Conventional technology]

In general, a hybrid integrated circuit board has a semiconductor mounted thereon and must be bonded with gold wire, and may be plated with a noble metal for the purpose of rust prevention, solderability, etc. of the conductor.

In recent years, the use of metal-based substrates has rapidly increased due to the demand for high-density packaging.

Due to the structure of a metal base board, the conventional method of mechanically removing plated lead conductors may cause cracks in the insulating layer, destroy the insulating layer, and cause defects in the insulation between the conductor and the base metal. Since this causes problems, it is removed by an etching method.

[Problems that the invention attempts to solve 1 to 1]
There is a method of applying plating-resistant tape on the plated lead conductor (Japanese Patent Application Laid-Open No. 59-31097, Japanese Patent Application Laid-Open No. 58-2256).
Publication No. 97]. The method disclosed in the publication attempts to remove the tape after plating and remove the plated lead conductor portion by copper etching.

In this method, there is a lead line between the circuit conductors,
If the distance between circuit conductors is narrow, it is impossible to apply plating-resistant tape to the lead line.

Another option is to use a photographic method to provide anti-metallic resist, but since the lead lines between minute circuit conductors are masked with extremely fine widths, precious metals may peel off during plating or the plating solution may seep in. However, there is a problem in that copper etching cannot cut and remove the precious metal plating lead line.

In order to completely prevent insulation failure due to insufficient lead line removal when copper etching is performed, and to smoothly form fine circuits, the plated lead line portions are also plated with noble metal, and then the circuit board is coated with a photosensitive liquid etching resist. The present invention provides a method for manufacturing a circuit board in which the plated lead line portion is exposed using a photographic method (1), the precious metal is etched, the nickel and copper are etched, and the plated lead line portion is removed .

[Means for Solving the Problems] That is, the present invention provides a method for manufacturing a circuit board plated with a noble metal on a metal base board formed by laminating copper foil on a base metal plate via an insulating layer. removable lc
The first step is to form a protective layer and provide an etching resist on the surface of the copper foil.The second step is to etch the copper foil and then remove the etching resist.The surface of the copper foil is plated with nickel and then with a precious metal. The third step is electrolytic plating, and the fourth step is to apply etching resin to the areas other than the plating lead and plating electrode using a photographic method. and a fifth step of etching the copper, and a third step of removing the etching resist'f: This is a characteristic method for manufacturing a noble metal plated circuit board.

The misfire 1311 will be explained below with reference to the drawings. .

FIG. 1 is a completed cross-sectional view of the hybrid integrated circuit board of the present invention, in which a copper foil 3'f: is laminated on a base metal 1 via an insulating layer 2, and further, nickel 4 and noble metal 5 are laminated in sequence on the copper foil 3. be.

The manufacturing process of the circuit board of the present invention is carried out in the first step by using a substrate in which a copper foil 3 is laminated on the entire surface of a base metal 1 with an insulating layer 2 interposed therebetween. Then, coat the parts necessary for the refill, the plating electrode and the plating lead part with a photosensitive liquid etching resotro, and then apply the base metal 1.
A protective film 7 is attached to the other metal surface of the (FIG. 2A, B).

Next, the exposed copper foil 3 is etched to form a circuit,
At the same time, a plating electrode 8 and a plating lead 9 necessary for electrolytic plating are formed, and the photosensitive liquid etching resistor is removed (FIGS. 6A and 6B). FIG. 4A shows the third step.

B is a layered structure in which nickel 4 and noble metal 5 are sequentially plated and laminated by electrolytic plating on the circuit part, the plating electrode, and the plating IJ-de. In order to remove the plating electrode and the plating lead, the part that will become the circuit section is shown coated with a photosensitive liquid etching resostro (fourth step).

In the fifth step, first, only the exposed noble metal 5 is removed using an etching agent (FIGS. 6A, 6B), and then the nickel 4 and the copper foil 3 are simultaneously removed using an etching agent (FIGS. 7A, 7B). B).

The present invention further provides that the etching resist coated with the photosensitive liquid etching resist 6 is removed as a final necessary part (FIGS. 8A and 8B), and the protective film 7 of the base metal 1 is removed as necessary. By cutting the outer periphery of the base metal 1 accordingly (FIGS. 9A and 9B), the circuit board shown in FIG. 1 can be manufactured.

The material used as the base metal 1 of the present invention is a metal plate having good thermal conductivity such as aluminum, copper, aluminum alloy, copper alloy, and alumite.
For example, thermosetting resins such as epoxy resins, polyimide resins, and phenolic resins containing inorganic powders with good thermal conductivity, such as alumina powder, boron nitride powder, beryllia powder, magnenia powder, and quartz powder, have good thermal conductivity. It has good properties and is preferable as a resin for insulating the base metal 1.

According to the present invention, only the resolution of the etching resist controls the cutting width of the plating lead (plating electrode and plating lead) portion, so by using, for example, a photosensitive liquid etching resist 7, etc. This means that even minute plated leads can be cut. In addition, for noble metal plating, aqua regia can be used to etch the gold or silver plated on the top layer of all 9 layers, but since there are handling problems, the present invention uses iodine and alkali metal iodides, such as iodine. Sodium chloride, lithium iodide, potassium iodide, etc. are preferable, and they can etch gold and silver at high speed.

Next, the nickel and copper in the lower layer are treated well with iron chloride solution.

Etched by.

〔Example〕

Examples of the present invention are shown below, but the present invention is not limited thereto.

Example A protective film was laminated on the base aluminum surface of an aluminum base copper-clad insulating substrate (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: Denka HI'l"T plate), and the copper foil surface was T-coated with a photosensitive liquid eratin breath. After drying, an image is formed using a photographic method, a circuit is formed by copper etching, the etching resist is removed, a protective tape is applied to the end face of the aluminum base, and the thickness of electrolytic nickel is 5 μm and the thickness of electrolytic pure gold is 0.5 μm. Next, a photosensitive liquid etching resist was coated, and after drying, the plating leads (plating electrodes and plating leads) were exposed using a photographic method, and iodine 5011, potassium 250I and water were plated. Pure gold was etched by treatment with 700 g of composition solution.Next, after washing with water, nickel and copper were etched with iron chloride (40° Baume) solution.Next, the photosensitive liquid etching resist was removed, and 150%
A fine circuit was formed by removing the plated leads from a pattern having plated leads on the pm.

[Effects of the Invention] According to the present invention, a fine circuit metal base board with excellent gold wire bonding and densification properties can be manufactured, and pattern short defects due to residual plating leads do not occur, making it suitable for manufacturing fine circuit boards for high-density mounting. Extremely useful.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a noble metal plated microcircuit metal base substrate according to the present invention. FIGS. 2 to 9A are cross-sectional views showing the steps of the present invention, and FIGS. 2 to 9B are plan views. DESCRIPTION OF SYMBOLS 1... Base metal plate, 2... Insulating layer, 3... Copper foil, 4... Nickel, 5... Blue gold Jil, 6... Etching resist, 7... Protective film, 8... Electrode for plating, 9... Lead for plating. Patent Applicant Denki Kagaku Kogyo Co., Ltd. Procedural Amendment (Method) May 1, 1985 Director General of the Patent Office Michibe Uga 1, Case Description 1985 Patent Application No. 27923 2, Title of Invention Precious metal plating circuit Substrate manufacturing method 3. Relationship with the case of the person making the amendment Patent applicant address ■100 1-4-1 Yurakucho, Chiyoda-ku, Tokyo April 22, 1986 (shipment date) 5. Subject of amendment

Claims (1)

[Scope of Claims] 1. A method for manufacturing a precious metal-plated circuit board of a metal base board formed by laminating copper foil on a base metal plate via an insulating layer, in which a removable protective layer is formed on the base metal surface. death,
a first step of providing an etching resist on the surface of the other copper foil; a second step of etching the copper foil and then removing the etching resist; a third step of electrolytic plating in which the surface of the copper foil is plated with nickel and then with a precious metal; a fourth step of applying an etching resist to a portion other than the plating lead and the plating electrode using a photographic method; a fifth step of etching the noble metal of the plating lead and the plating electrode; and further etching nickel and copper; A method for manufacturing a noble metal plated circuit board, comprising a sixth step of removing an etching resist. 2. The method for manufacturing a circuit board according to claim 1, wherein the noble metal is gold or silver.