JPH02231788A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To form a fine circuit by using a photosensitive resin film as a printing resist. CONSTITUTION:A photosensitive resin film 1 is stuck, and a photosensitive resin layer formed onto an insulating resin board is exposed by employing a photo-tool, thus preparing a printing resist 4 having the negative shape of a desired circuit pattern. A conductive resin is pushed into a groove shaped by a squeegee 5, the resin is cured and a conductor is formed, and the resist 4 used for printing is peeled. Consequently, conductive paste 6, 7 are placed only on a desired circuit shape section, in which there is no printed resist 4, on the substrate though the whole surface is coated with the conductive paste 6, 7 by the squeegee 5 by a printing resist layer. Accordingly, a thin circuit is formed without limiting circuit width capable of being printed and a direction, etc., and can be shaped easily by a pattern rectangular in the direction of the progress of the squeegee.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a printed wiring board using a conductive resin paste as a conductor.

In the present invention, instead of the conventional method of forming conductive paste circuits by screen printing, a printing method using a photosensitive resin film as a printing resist is adopted, thereby achieving high-density circuit printing and high printability. This is to obtain membrane pressure reproducibility.

Conventional technology> Currently, the method for producing printed wiring boards is to use a laminated copper foil on an insulating resin plate, form a suitable etching resist on the copper foil, and etch a suitable etching resist such as cupric chloride. A common method is to etch the copper foil with an etchant.

Due to the increasing trend towards digitalization of circuits and advances in circuit technology in recent years, it is no longer a problem even if the electrical resistance of the pattern on the board as a wiring material is high to a certain extent. The electrical resistance of conductive resin paste is also decreasing.

Against this technical background, in order to respond to the severe price competition in recent years, conductive resins are being used as circuit conductors, mainly for things that do not require large currents to flow, such as liquid crystal display (L■) connections. There is a growing trend to do so.

FIG. 2 shows a method of manufacturing a substrate using a general conductive paste.

Reference numeral 11 is an insulating resin plate serving as a substrate base, 12 is a conductive resin paste, 13 is a squeegee, and 14 is a screen plate prepared so that the resin passes through the desired circuit pattern shape. The circuit is formed using the screen plate 14 described above. This method is generally known as screen printing.

<Problems to be Solved by the Invention> In the screen printing method described above, problems such as bleeding of the resin paste, elongation and distortion of the screen plate, and roughness of the mesh have large limitations on the width and direction of circuits that can be printed. However, it has the disadvantage that it can only be applied to relatively simple patterns.

Particularly noteworthy is the screen plate, which is usually made of elastic mesh made of resin fibers such as nylon, which makes accurate printing difficult due to expansion and contraction. Bleeding occurs because the base material cannot be completely adhered.

In view of the above-mentioned points, the present invention provides a method for easily forming a thin circuit or even a pattern perpendicular to the squeegee advancing direction without any restrictions on the circuit width or direction that can be printed.

Means for Solving the Problems> The present invention provides a method for manufacturing a printed wiring board obtained by forming a conductive resin paste on an insulating resin plate in a desired circuit pattern shape. A method that uses a printed resist made of a photosensitive resin film as a means of forming a conductive paste in the shape of a pattern.
The photosensitive resin layer formed on the insulating resin substrate is bonded together and exposed using a 7-oto tool to create a printing resist with a negative shape of the desired circuit pattern. The method is characterized by the following steps: filling the groove with a conductive resin with a squeegee, curing the resin to form a conductor, and peeling off the resist used for printing.

As described above, through the process of laminating a photosensitive resin film, exposing it to light, and developing it, the printed resist layer is formed as a negative pattern in the desired circuit shape on the insulating resin substrate, and the conductive resist layer is formed with a squeegee using a squeegee. Even though the paste is coated over the entire surface, only the desired circuit shape without printing resist is placed on the substrate. Furthermore, in this case, the height of the squeegee is limited by the thickness of the dry film that is the printing resist, and the film thickness of the printed conductive paste can be kept constant.

Embodiment> FIGS. 1(a), (b), (c), (d), and (e) K show the printing process in one embodiment of the present invention.

1 is an insulating resin substrate, 2 is a photosensitive resin film, and the first
It is pasted onto the substrate l as shown in Figure (a). The photosensitive resin film 2 is suitably a so-called dry film, which is commonly used in the manufacture of printed wiring boards. The thickness of this dry film 2 is selected depending on the desired thickness of the resin paste circuit.

Next, as shown in FIG. 1(b), a circuit pattern is exposed on the material to which the dry film 2 is pasted using the photo tool 3.

Due to the exposure of the circuit pattern, the resin of the dry film 2 undergoes photopolymerization or collapse, and the subsequent development process causes the resin of the dry film 2 to undergo photopolymerization or collapse.
As shown in FIG. 1(C), the printed resist 4 finally has a negative shape of a pattern desired as a circuit shape.

Next K1 As shown in FIG. 1(C), conductive paste (copper paste, silver paste, palladium paste, etc.) 6 is embedded in the portions of the substrate 1 where there is no printing resist 4 using a squeegee 5. In FIG. 1(d), 7 is the embedded conductive paste.

Next, the conductive paste 7 is cured by heating, electron beams, ultraviolet rays, etc., and then the printing resist 4 is removed with a solvent or other suitable means, as shown in Figure L<e). A circuit pattern 8 made of conductive resin is formed on the substrate l.

According to this method, L: It is possible to print fine patterns.

In conventional screen printing methods, the limit is said to be a line width of about 0.2 to 0.8 mm, and furthermore, for parallel lines perpendicular to the direction of travel of the squeegee, wider bits were required. However, according to this method, even a line width as high as the resolution of the dry film 2 (about 0.05 m) is possible. Moreover, as in the conventional method, the directional relationship between the pattern 8 and the squeegee 5 is also
Not restricted.

2. Easy control of circuit thickness of conductive paste In conventional screen printing methods, it is very difficult to accurately maintain the amount of paste coming out of the plate. This means that it is extremely difficult to keep the circuit resistance constant, and in many cases,
It was often necessary to make adjustments using other circuit components, create more margin in the circuit, or trim the circuit again using laser light.

According to this method, the conductive paste 7 formed on the substrate 1
The thickness of is regulated by the thickness of dry film 2,
Extremely stable membrane pressure reproducibility can be obtained. This means that the circuit forming method according to the present method, in addition to simply obtaining a conductive circuit,
This shows that it is possible to stably produce resistors as circuit elements by simultaneously printing them.

Effects of the Invention> As described above, according to the present invention, a photosensitive resin film is used as a printing resist to make it possible to form a fine circuit, which is difficult to form using conventional screen printing methods. A method for manufacturing a printed wiring board can be provided.

[Brief explanation of the drawing]

1(aXb)(c)(d)(e) are process diagrams showing one embodiment of the present invention, and FIG. 2 is a main process diagram showing a conventional example. 1... Insulating resin film, 2... Dry film,
3...Photo tool, 4...Print resist, 5...
・Squeegee, 6, 7... Conductive paste, 8... Circuit pattern O Agent: Patent attorney Takeshi Sugiyama (and 1 other person) Figure 1/. ? ll Figure 2

Claims (1)

[Claims] 1. In the manufacturing method of printed wiring boards obtained by forming a conductive resin paste into a desired circuit pattern shape on an insulating resin board, a photosensitive resin film is bonded to the insulating resin plate. The photosensitive resin layer formed on the substrate is exposed using a photo tool to create a printing resist with a negative shape of the desired circuit pattern, and the conductive resin is applied to the grooves formed by this using a squeegee. A method for manufacturing a printed wiring board, comprising the steps of embedding a paste, curing the resin paste to form a conductor, and peeling off a resist used in printing.