JPS61123197A - Manufacture of printed wiring 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 for manufacturing printed wiring boards used for internal wiring of information equipment and the like.

Conventional configurations and their problems In recent years, printed wiring boards have become more dense and multilayered, wiring board materials have become thinner, and they have become more multifunctional in response to the demand for smaller, lighter, and thinner electronic devices. It's getting worse. Among these trends, the growth of flexible printed wiring boards is particularly noticeable, and examples of their adoption are increasing from fields such as cameras and calculators, which have traditionally been widely used, to OA equipment centered on personal computers.

The conventional manufacturing method for flexible printed wiring boards is as follows:
First, as shown in Figure 1, a thermosetting adhesive 2 such as epoxy resin is applied to an insulating film 1 such as a polyimide resin film, Holieste/v41, and a copper foil 3 (generally an electrolytic copper foil (with a thickness of 18μ to 35μ) and then laminated continuously using a heat roll method or other means to create a copper foil film, and in the case of a single-sided flexible printed wiring board, as shown in Figure 2 a - c Copper foil 3
A circuit-shaped resist 1 pattern 4 was formed on top, and ferric chloride was used.

Etch the exposed copper foil surface with an etching solution such as cupric chloride,
After forming the desired conductor circuit, the resist 1 4 is peeled off, and an insulating layer is formed with the main purpose of protecting the conductor circuit 6, improving insulation properties, and improving flexibility. This insulating layer is generally called coverlay or overlay, but it is flexible! [Polyimide resin film due to the properties required.

In many cases, an insulating film 1 such as a polyester resin film coated with an epoxy adhesive or the like is used, and the insulating layer is formed by thermoforming.

As can be seen from the above manufacturing method, in the conventional flexible printed wiring board, the adhesive 2 and the insulating film 1 are always placed under the conductor circuit 6, making it difficult to connect with a rigid wiring board. Although they are increasingly being used in electronic devices, their scope of use is currently limited due to mounting problems such as the inability to mount electronic components due to their thinness. Therefore, it has been desired to solve the above-mentioned problems and to develop a flexible printed wiring board with flexibility, but as shown in JP-A-62-166395 shown in 2 to 1.0 mm thick) is selectively corroded, leaving a relatively thick metal plate in the component mounting area 6 on the insulating film, and corroding the metal plate in the part 7 that requires flexibility to make it thin < (0, 03~0.1mm thickness),
A flexible print that solves the above-mentioned problems and realizes flexibility by forming a thick metal terminal part 8 outside the insulating film 1 as an extension of the conductor circuit for connection with a rigid wiring board while forming a conductor circuit. A wiring board has been developed and commercialized.

However, with the above-mentioned flexible printed wiring board with terminals, it is not possible to manufacture a double-sided wiring board due to the manufacturing method, and in the example, a thin part of 0.076 mm is required for the 0.26 mm thick copper plate. When , Cj0
Based on the description that corrosion should be controlled by etching once from one side to a depth of 75 mm, it was predicted that it would be difficult to finish the conductor circuit width and conductor circuit spacing with precision, and the commercialized flexible print was developed. This is also recognized as a restriction for wiring boards. In other words, it can be said that this manufacturing method is not suitable for high-density conductor circuits, including double-sided fabrication.

In addition, due to the manufacturing method of conventional flexible printed wiring boards, the metal foil must be corroded from one side.
The method of simply increasing the thickness of the metal foil layer has a limit to the ability to produce high-precision conductor circuits.

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention is capable of forming a high-density conductor circuit with a relatively thick conductor, has conductor circuits on both sides, and has a metal terminal portion in the part where there is no insulating film. The present invention provides a method for manufacturing a printed wiring board that forms a printed wiring board.

Structure of the Invention In order to achieve this object, the manufacturing method of the present invention includes a step of forming a resist pattern on the front and back sides of a metal plate, a step of half-etching the metal plate, and a step of applying an adhesive to the front and back sides of the insulating film. The process of drying to the touch, aligning the two half-etched metal plates on the front and back sides of the insulating film,
Thermoforming process, re-etching the thermoformed insulating film and metal plate to form conductor circuits on both sides, and forming an insulating film layer for protection and mechanical strength of the conductor circuits. It consists of a process and a resist stripping process to expose the conductor circuit in critical parts.

By performing this configuration and half-etching on both sides of the metal plate simultaneously, it becomes possible to form a relatively thick conductor circuit with a high density pattern, and it also becomes possible to form metal terminal portions and obtain a double-sided printed wiring board.

DESCRIPTION OF EMBODIMENTS The present invention will be described below based on one embodiment with reference to the drawings.

As shown in FIG. 4, the metal plate 9 is o, i~0,2Lo.
An etching resist film 4 is formed on the front and back surfaces of a metal plate 9 using a copper plate or a copper alloy plate having a thickness of m. In this case, if the final required conductor circuit width or conductor circuit spacing is 0.2 mm or more, use the screen printing method, or if it is less than 0.2 a + m, apply a liquid photoresist to the entire surface of the front and back of the metal plate.
Drying, exposure, development, etc. are performed to form etching lenses NIA on both sides of the metal plate.

Next, half-etch with an etching solution such as ferric chloride or cupric chloride to form the state shown in Fig. 5, and apply epoxy adhesive 2 or the like on the front and back of a thin insulating film 10 such as a polyimide resin film for 20 to 30 minutes. After applying a cloth to a thickness of 60 μm and drying it to the touch, it is perforated or contoured into a predetermined shape, aligned as shown in Figure 6, and then thermoformed to create a half-etched sand-notched structure of the metal plate. Let it form.

The thermoforming conditions are 130-i for EBOKI 7 adhesive.
yo'C, pressure "~" kg/ra, heating time 2
0 to 40 minutes is appropriate.

Next, under almost the same conditions as the first half-etching,
The etching process is performed again to simultaneously form predetermined conductor circuits as shown in FIG. 7 on both sides of the insulating film.

Next, apply Evoquin adhesive or the like to a thickness of 2Q to 60 μm on one side of an insulating film such as a polyimide resin film, and then apply a thin insulating film with adhesive that is dry to the touch to the specified shape V.
<-Drill or profile, align with the conductor circuit, thermoform again, and remelt, bond, and fix with the adhesive on the insulating bulk of the base sandwiched between the conductor circuits.

As shown in Figures 8 and 9, the exposed resist film is chemically or mechanically peeled off to expose the copper surface 1o for electrical connection with external circuits, lead wires, hard wiring boards, etc. After applying anti-shao roasting process 1 using pre-flux of Ronn yarn or imitasol yarn, external perforation processing is performed to obtain a 7°IJ, 71~ wiring board.

Effects of the Invention As described above, according to the present invention, it is possible to manufacture a JI (thin plate thickness) printed circuit board that is heavy density, has a relatively thick conductor, has metal terminals, and is double-sided. Conventional flexible printed circuit boards, such as power supply circuits, are more likely to be adopted in fields where they are not suitable, and electronic equipment is becoming lighter and shorter, streamlining internal wiring, and increasing design freedom. The practical value of this increase is great.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the copper-clad film, Figure 2 (tel-(c))
Figure 3 is a cross-sectional view showing a conventional method of manufacturing a single-sided flexible printed wiring board, and Figure 3 shows conventional printed wiring. A perspective view of the board, FIGS. 4 to 8 are sectional views showing a method of manufacturing a printed wiring board according to an embodiment of the present invention, and FIG. 9 is a perspective view of a printed wiring board according to the same manufacturing method. 1...Insulating film, 2...Adhesive,
3...--Conductor (copper) foil, 4...Resist film, 6...Conductor (copper foil) circuit, 6...
Part mounting part, 7... Part that increases flexibility by 1'',
8...Metal terminal part, 9...Metal plate, 1
0...Conductor exposed portion, 11...Perforation. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 and l Figure 4 Figure 7 Figure B Figure 8 Figure 9 O

Claims (1)

[Claims] Two metal plates with resist layers formed on the front and back sides and partially corroded with an etching solution are thermoformed into a structure sandwiching an insulating film coated with adhesive on the front and back sides, and the same is re-corroded with the etching solution. A method for producing a printed wiring board, comprising forming conductive circuits on both sides of the insulating film at the same time by causing corrosion to a certain extent, and removing only the exposed portions of the resist layer on the conductive circuits.