JPH0563111B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a printed circuit board.

(Prior art) Conventional methods for manufacturing printed circuit boards include, for example, laminating a copper plate and a board material by hot pressing and then etching the surface of the copper plate to form a circuit pattern, or applying conductive ink to the board material. Methods of forming circuit patterns by screen printing or electroless plating are often used.

In recent years, thermoplastic resins such as polysulfon, polyethersulfon, and polyetherimide, which have excellent heat resistance and electrical properties, have appeared as materials for substrates, replacing conventional glass epoxy. Attempts have been made to injection mold the substrate body. When molding the board body by injection molding, in addition to improving the heat resistance, dielectric constant, dielectric loss tangent, and other electrical properties of the resin material, the board shape, through holes, mounting parts, and other additional shapes are integrated. It has the great advantage of eliminating the need for post-processing such as cutting or pressing as required in the past. A circuit pattern is formed on the surface of the substrate main body obtained by this injection molding by the above-described printing, plating, or other means.

(Problems to be Solved by the Invention) Based on the background of the above-mentioned prior art, the present invention proposes that the circuit portion is also integrally molded during injection molding of the board.

That is, in the above-mentioned conventional technology, the process of molding the circuit part is required after the injection molding of the board, but in the present invention, by molding the circuit part at the same time as the injection molding of the board, This dramatically simplifies the manufacturing process for this type of printed circuit board,
It also aims to improve efficiency.

In particular, the present invention seeks to propose a method for manufacturing a printed circuit board in which a circuit pattern is integrally and firmly bonded to the board via a base film.

(Means for Solving the Problems) That is, in the method for manufacturing a printed circuit board according to the present invention, a mold surface of a cavity having a board shape is coated with a synthetic resin that is the same type or compatible with the resin constituting the board. A circuit film having a circuit pattern made of conductors constituting a printed circuit formed on the surface of the base film is arranged so that the circuit pattern is on the mold side and the base film surface is on the inside of the cavity. After closing the mold, Molten resin constituting the substrate is injected into the cavity, and the circuit film is pressed onto the mold surface by the injection pressure of the molten resin, and the base film and the molten resin are fused and welded to join the substrate. The present invention is characterized in that a printed circuit board having a circuit pattern flush with the surface of the board integrally embedded therein is obtained.

(Function) In this invention, a circuit film is used in which a circuit pattern made of conductors constituting a predetermined printed circuit is formed on a base film made of a synthetic resin of the same type or compatible with the resin constituting the substrate. Ru. Then, during injection molding of the board, this circuit film is placed in the board cavity with the base film surface facing inside the cavity, and molten resin constituting the board is injected.

Since the molten resin injected into the cavity is made of the same kind of synthetic resin as the circuit film or is compatible with the circuit film, it is fused and welded to the base film disposed inside the cavity, and is integrally and firmly joined to the substrate. A printed circuit board is obtained which is molded into a shape and has a circuit pattern embedded flush with the surface of the board.

(Example) Embodiments will be described below with reference to the accompanying drawings.

FIG. 1 of the accompanying drawings is a cross-sectional view of essential parts showing an example of an injection molding apparatus for carrying out the method of the present invention, FIG. 2 is a partially enlarged cross-sectional view showing an example of a circuit film, and FIG. 3 is a similar circuit film. FIG. 4 is a partially enlarged sectional view of the mold showing the state before molding, FIG. 5 is a partially enlarged sectional view of the mold during molding, and the sixth example is this. FIG. 2 is a partially enlarged sectional view of a printed circuit board obtained according to the invention.

FIG. 1 shows an injection molding apparatus for carrying out the method of the invention.

That is, one mold, in the example, the fixed type 20
On the side, a cavity 10 having the shape of a substrate is formed by a cavity plate 11 . When a through hole is formed in the substrate, a pin 15 is erected at a predetermined position within the cavity 10.

The other mold, in the embodiment, the movable mold 21 side is provided with a cavity plate 13 that defines the substrate surface shape. The cavity plate 13 is formed into a flat (or curved, if necessary) plate shape, and the circuit film 30 is placed at a predetermined position.

In FIG. 1, reference numeral 22 is a fixed mounting plate, 23 is a movable mounting plate, 25 is a sprue hole, 26 is a sprue bush, and 29 is a circuit film 3.
The clamp for holding 0 on the cavity plate 13 represents an injection machine.

Circuit film 30 used in this invention
As shown in FIG. 2 or 3, a circuit pattern 31 made of a conductor constituting a printed circuit is formed on the surface of a base film 32 made of a resin that is the same type or compatible with the resin constituting the substrate. It is something. Generally, heat-resistant plastics are used as resins for injection molding of this type of substrate.
PPS, PEI, PES, PSF, etc. are used, and general-purpose plastics include ABS, PMMA, polycarbonate, etc., but it is desirable to select the same type of base film 32 as the substrate resin as much as possible. In the example, PPS is used as the substrate resin.
A PPS film was used as the base film 32.

The circuit pattern 31 is made of a conductor such as copper foil,
It is formed on the surface of the base film 32 by known means such as printing, vapor deposition, or plating.

The circuit film 30 shown in FIG. 2 has a circuit pattern 31 made of copper foil formed on the surface of a base film 32 by vapor deposition or plating, and the reference numeral 33 in the figure indicates a masking mask remaining on the surface. 34 and 35 are adhesive layers. These masking portions 33 and adhesive layers 34 and 35 are melted by heat during substrate molding.

Further, the circuit film 30A shown in FIG. 3 has a circuit pattern 31 formed directly on the upper surface of a base film 31 by printing.

4 and 5 are partially enlarged sectional views of the mold cavity during molding.

In the present invention, as shown in FIG. 4, a circuit film 30 is arranged in a substrate cavity 10 so that the base film 32 side faces the cavity side.

Then, as shown in FIG. 5, the molten resin P constituting the substrate is injected into the cavity 10, and the base film 32 of the circuit film 30 and the molten resin P are integrally joined to form the substrate. Ru.

At this time, since the base film 32 and the substrate resin P are of the same type or are compatible with each other, at the joint part in the cavity, as shown in FIG. can be fused and welded together to obtain a strong integral bond.

In addition, when injection molding the substrate, as shown in FIG. 5 or 6, the substrate resin P is placed on the circuit film 3
The base film 32 of No. 0 is pressed from the back side to tightly press the circuit pattern 31 on the front surface against the cavity plate 13, so that the surface of the substrate is made flush as shown in the figure.

(Effect) Printed circuit board B obtained as above
As shown in the partially enlarged sectional view of FIG. 6, the base film 32 of the circuit film 30 and the substrate resin P
Since the two are fused and welded at the joint, an integral and strong joint can be obtained.

Further, as can be understood from the figure, the base film 32 of the circuit film 30 is buried flush with the surface of the substrate so as to wrap the circuit pattern 31 during injection molding of the substrate, so that the circuit pattern 31 is firmly attached to the surface of the substrate. wrapped and fixed.

Furthermore, since the circuit pattern 31 is buried flush with the substrate surface, it can be used on sliding parts without peeling off.

FIG. 7 is a partially enlarged cross-sectional view of a conventional printed circuit board 50. In the case where a printed circuit board 51 is formed protruding from the surface of the board 50 as in this example, it is difficult to bond the printed circuit 51. It has low properties and may be damaged by contact with other objects.
It is difficult to use on sliding parts or parts that come into contact with other objects because there is a risk of peeling off.

According to this invention, in addition, the base film is made of a resin of the same type or compatible with the substrate resin, and is fused and welded together with the substrate resin during molding, so that the base film is made of a heat-resistant or strong resin. It is economical as it does not require Further, injection molding of the substrate can be carried out without any special restrictions such as keeping the mold temperature and resin temperature low, and great advantages can be enjoyed in terms of molding.

As described above, according to the present invention, the circuit part can be integrally formed at the same time as the injection molding of the board, and in particular, the circuit pattern can be integrally and firmly joined through the base film, and this type of printed circuit board can be The manufacturing process can be dramatically simplified and made more efficient.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of essential parts showing an example of an injection molding apparatus for carrying out the method of the present invention, Fig. 2 is a partially enlarged cross-sectional view showing an example of a circuit film, and Fig. 3 is another example of the same circuit film. FIG. 4 is a partially enlarged sectional view of the mold showing the state before molding, FIG. 5 is a partially enlarged sectional view of the mold during molding, and FIG.
The figure is a partially enlarged sectional view of a printed circuit board obtained by the present invention, and FIG. 7 is a partially enlarged sectional view of a conventional printed circuit board. 10...Substrate cavity, 11, 13...Cavity plate, 20...Fixed type, 21...Movable type, 30...Circuit film, 31...Circuit pattern, 32...Base film, P...Substrate resin .

Claims (1)

[Claims] 1. A circuit film in which a circuit pattern made of a conductor constituting a printed circuit is formed on the surface of a base film made of a synthetic resin that is the same type or compatible with the resin constituting the substrate is placed on the mold surface of a cavity having a substrate shape. The circuit pattern is placed on the mold surface side and the base film surface is on the inside of the gear cavity. After closing the mold, molten resin constituting the substrate is injected into the cavity, and the circuit is formed by the injection pressure of the molten resin. Pressing a film onto the mold surface and fusion welding the base film and the molten resin to join them together, molding the substrate;
A method for producing a printed circuit board, characterized by obtaining a printed circuit board in which a circuit pattern flush with the surface of the board is embedded integrally.