JPH0199282A - Forming method for land of printed board - Google Patents

Abstract

PURPOSE:To bring the center of a land into coincidence with a through hole by forming a reflecting film on a transparent plate, reflecting a light transmitted via the hole to a board by the plate, and forming the land on the periphery of the hole. CONSTITUTION:After a dry film 11 and a transparent plate 12 are sequentially laminated on a copper foil 9, a reflecting plate 13 is provided on the plate 12. A predetermined light source 14 is radiated from the rear face of a substrate 7. The light from the source 14 is transmitted via a through hole 8, the film 11 and the plate 12 to the plate 13, and reflected on the plate 13 to the substrate 7. The part irradiated with the reflected light remains when it is developed, and becomes a land 10. The position, the quantity of light of the source 14 are suitably regulated. Then, the land 10 which becomes concentrical circle state with the hole 8 is formed. Thus, the center of the hole 8 is brought into coincidence with that of the land 10.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a manufacturing technology for printed circuit boards, and in particular to a method for forming lands on printed circuit boards for forming fine lands with high precision by a baking method. be.

(B) Conventional technology In the conventional method of forming lands on printed circuit boards using the baking method, as shown in Fig. 2, first a layer of copper foil is
After pasting, the dry film 3 and the negative printing film 4 are sequentially laminated, and the negative printing film 4 is exposed to light from above by a predetermined light source 5.

Then, the exposed areas 2a that are exposed to light through the dry film 3 and the negative printing film 4 (1% transmission) 3a, 4a remain during development, while the non-transparent areas 3b, 4b block the transmission of light. Non-exposed area 2b that is exposed to light and is not exposed to light
melts and disappears during development, thereby causing the substrate lJ:
and a predetermined land (the exposed portion 2a).

(c) Problems to be Solved by the Invention However, according to the conventional method of forming a runt on a printed circuit board using the above-mentioned printing method, the transparent portion 4a of the printing negative film 4 is expanded and deformed due to temperature changes, etc. The position of the through hole 6 is slightly deviated from the predetermined one-step position, and as a result, the center position of the land formed is deviated from the center position of the through hole 6, resulting in a defective land.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, an object of the present invention is to provide a method for forming lands on a printed circuit board, which allows the centers of the lands and through-holes to coincide with each other.

(d) Means for solving the problems The method for forming lands on a printed circuit board according to the present invention includes:
In the process of creating a printed circuit board in which metal foil wiring is applied to an insulating substrate surface, in order to form a land around a through hole, first a dry film and a transparent plate are laminated on the substrate with metal foil attached, and then the transparent plate is laminated. The present invention is characterized in that a reflecting plate is provided on the through-hole, and the light passing through the through-hole is reflected toward the substrate by the reflecting plate, thereby forming a land around the through-hole.

(E) Function According to the method of the present invention, lands are formed by reflecting light from a reflector without using a conventional negative film for printing, so that expansion and contraction deformation of the negative film due to temperature changes etc. Lands can always be formed at predetermined positions with high precision.

(f) Example The present invention will be described in detail below using an example shown in FIG.

FIG. 1 is a sectional view of a printed circuit board for explaining the method of the present invention.

The insulating substrate 7 is made by hardening glass laminated glass, cloth, paper, etc. into a laminated plate shape using epoxy resin, phenol resin, or the like. A through hole 8 is provided in the insulating substrate 7.
is drilled and copper foil 9 is pasted on it.

In the present invention, lands 1O are formed on the front and back surfaces of the through hole 8, and after laminating a dry film 11 and a transparent plate 12 on one side of the copper foil 9 in order, the transparent plate 1
A reflecting plate 13 is provided on top of the insulating substrate 7, and a predetermined light source 14 is irradiated from the back side of the insulating substrate 7.

Then, the light from the light source 14 passes through the through hole 8, and then passes through the dry film 11. The light passes through the transparent plate 12 and hits the reflective plate 13, where it is reflected toward the insulating substrate 7. The portion exposed to the reflected light remains after development and becomes runt lO.

Incidentally, the position of the light [14], the amount of light, etc. are adjusted as appropriate so that the light reflected here forms a concentric circle around the through hole 8 with the hole position of the through hole 8 as the center. As a result, a runt 10 is formed around the surface of the through hole 8 with good precision, that is, a runt 10 that is concentric with the through hole 8.

On the other hand, when forming a land IO around the back surface of the through hole 8, the reflector 13 is placed on the cut-out side of the insulating substrate 7, and a predetermined light source 14 is irradiated from the front side of the insulating substrate 7. This is done by

In this way, not only is it not necessary to prepare a negative film, but the land is also
Accuracy of O is not affected adversely and always land lO
can be precisely formed at a predetermined position 1a'.

(G) As described in detail of the invention, according to the land forming method for a printed circuit board according to the present invention, in forming a land around a through hole, first, a dry film is placed on an insulating substrate to which metal foil is attached. After sequentially laminating the transparent plates, a reflective plate was placed on the transparent plate, and the light passing through the through hole was reflected to the substrate side, thereby forming a land around the through hole. Therefore, compared to the case of using conventional negative printing film, it is possible to eliminate the problem of the formation position of the land shifting from the predetermined position due to expansion and contraction deformation of the negative printing film due to temperature changes, etc., and it is possible to easily and reliably form through holes. This has the effect that the center of the land can be made to coincide with the center of the land.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a printed circuit board for explaining the method of the present invention, and FIG. 2 is a sectional view of a printed circuit board for explaining the conventional method. 7 ~ Insulating board 8 ~ Through hole 9 ~ #I4 foil 10 ~ Runt ■ 1 ~ Tri film
12 ~ Transparent plate 13 ~ Reflective plate October 12, 1988

Claims (1)

[Claims] In the process of creating a printed circuit board in which metal foil wiring is applied to an insulating substrate surface, in order to form a land around a through hole, first a dry film and a transparent plate are sequentially laminated on the substrate with metal foil attached, and then the transparent Land formation in a printed circuit board, characterized in that a reflective plate is provided on the board, and the light that has passed through the through hole is reflected toward the board side by the reflective plate to form a land around the through hole. Method.