JPS63232390A - Manufacture of through-hole 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 (a) Industrial Application Field This invention uses a photosensitive etching resist to
(b) Conventional technology related to a method for manufacturing a through-hole wiring board including a step of etching conductor parts in non-circuit parts. Conventional methods for manufacturing a through-hole wiring board include a hole-filling method and a solder stripping method. These methods have disadvantages such as through-hole chipping and increased chemical costs. Recently, a method has been proposed in which a photosensitive etching resist is formed on circuit parts including through-holes by electrodeposition, thereby eliminating the drawbacks of the above methods and forming a high-density wiring pattern. With this electrodeposition coating method, the photosensitive etching resist reliably adheres to the inner surface of the through hole, and the film thickness of the resist film can also be easily controlled.
It becomes possible to form a fine pattern of 0 micron or less, for example, 20 to 30 wiring lines between pins of an IC. In this method, the entire surface of the board is exposed with the photosensitive etching resist exposed in the circuit area including through holes, and then the etching resist placed on the circuit area is exposed.
will be removed.

(C1 Problem to be Solved by the Invention However, in the above conventional method using a photosensitive etching resist, when the entire surface of the substrate is exposed, the inner wall of the through hole may not be irradiated with sufficient light. Fifth
The figure shows this situation. A conductor portion 2 made of a material such as copper is formed on the entire surface of the substrate 1 and the inner wall of the through hole, and a photosensitive etching resist 3 is formed on the circuit portion including the inner wall of the through hole by electrodeposition coating. The entire surface of the substrate is exposed by the lamp 5. At this time, the circuit portion on the surface of the substrate 1 is sufficiently irradiated with the ultraviolet rays 5a, but the inner wall of the through hole 4 is not sufficiently irradiated. For this reason, the etching resist 3 on the inner wall of the through hole is not sufficiently cured, and there is a possibility that the uncured etching resist 3 may be peeled off from the inner wall of the through hole during substrate cleaning.

An object of the present invention is to provide a method for manufacturing a through-hole wiring board in which the inner walls of the through-holes are sufficiently exposed during exposure, thereby increasing the reliability of the through-hole portions.

(Means for solving problem d1) In this invention, after forming a conductor part on the entire surface of a board including through holes, a photosensitive etching resist is exposed only in the circuit part including through holes, and then one side of the board is exposed. A diffuse reflection plate is placed on one side, and the other side is completely exposed to light.The process is performed on both the upper and lower surfaces of the substrate, and the conductor portions in areas other than the photo-cured etching resist are removed by etching to form a circuit pattern. Features.

<61 action The operation of this invention will be explained with reference to FIG.

FIG. 1 shows the exposure process of this invention. This exposure process differs from the conventional exposure process shown in FIG. 5 in that a diffused reflection plate 6 is disposed on the substrate surface opposite to the position where the ultraviolet lamp 5 is disposed.

Ultraviolet Na irradiated from the ultraviolet lamp 5 to the substrate 1
5a does not sufficiently illuminate the inner wall of the through hole when it passes through the through hole 4, as in the conventional case shown in FIG. However, it is diffusely reflected by the diffused reflection surface 6a and reaches the inner wall of the through hole. Therefore, as shown in the figure, the inner wall of the through hole is sufficiently irradiated with diffusely reflected light, and the amount of irradiation is substantially equal to that of the substrate 1.
The amount of irradiation is almost the same as that for the circuit section on the surface. The subsequent steps are exactly the same as the conventional manufacturing method. That is, the conductor portions other than the circuit portion including through holes are removed by etching to form a circuit pattern, and furthermore, the etching resist 3 covering the circuit portion is removed.

(f) Embodiment FIG. 2 shows a method for manufacturing a through-hole wiring board according to the present invention in the order of steps. Each process will be explained below.

A: The substrate 1 is formed by preparing a material such as glass epoxy, epoxy, paper phenol, etc.B: Holes are formed at predetermined locations on the substrate 1.

C: The inner wall of the hole and the entire front and back surfaces of the substrate 1 are subjected to known chemical plating to form a plating film 7.

D...Furthermore, an electroplated layer 8 is formed on the plating film deposited by the above chemical plating.

E: Further, areas other than the circuit portion on the electroplated layer 8 are covered with a suitable insulating film 9. This insulating film 9 is formed by a screen printing method or the like.

F...Subsequently, the above substrate is immersed in an electrodeposition solution, and electrodeposition is performed using the electroplating layer 8 as one electrode. Although any known electrodeposition solution can be used, in the present invention, one containing a photosensitizer that is hardened by ultraviolet irradiation is used. Through this step, a photosensitive etching resist 10 is formed in the circuit portion including the through holes.

G...Next, the above substrate is placed on the diffuse reflection plate 6, and the ultraviolet lamp 5 is placed above it to irradiate it with ultraviolet rays 5a.

As a result, the photosensitive etching resist 10 on the substrate surface
UV light 5a passes through the through hole as it hardens.
The light is diffusely reflected by the diffused reflection surface 6a of the diffused reflection plate 6a, and the inner wall of the through hole 4 is uniformly irradiated and hardened.

H: The diffused reflection plate 6 is placed on the top surface of the substrate, and the ultraviolet lamp 5 is placed below the substrate 1 to irradiate the back surface of the substrate with ultraviolet rays 5a. As a result, the photosensitive etching resist 10 on the back surface of the substrate is cured, and the ultraviolet rays transmitted through the through holes 4 are diffusely reflected by the diffuse reflection surface 6a of the diffuse reflection plate 6 and irradiate the inner walls of the through holes. In step G, the etching resist 10 on the inner wall of the through hole is in a hardened state, but in step H, the etching resist 10 inside the through hole is further completely hardened.

■...The diffused reflection plate 6 and the ultraviolet lamp 5 are removed, the insulating film 9 is removed with a weak alkaline solution, and the conductor part 9 in the non-circuit part is removed in an etching process (.

J...Furthermore, the etching resist 10 of the circuit portion is removed to complete the formation of the circuit pattern, and processing such as solder resist (not shown) is performed to complete the manufacture of the board.

In the above manufacturing method, since the photosensitive etching resist 10 is formed by electrodeposition coating in step F, a resist film with uniform film thickness is reliably formed on all circuit surfaces including through holes. be able to. Since the diffused reflection plate 6 is used for exposure in the steps G and H, the etching resist film on the inner wall of the through hole can be irradiated with sufficient ultraviolet rays.

FIG. 3 shows a part of the manufacturing method of the present invention using a photographic method. In the manufacturing method shown in FIG. 2 above, the insulating film 9 is formed by printing in the step E, and the etching resist 10 is formed only in the circuit area in the step F. However, as shown in FIG. In the manufacturing method, instead of step E above, an etching resist 10 is formed over the entire surface of the substrate (
E'). Then, in place of the step F, a negative film 9 covering the non-circuit portion is placed on the substrate, and the process proceeds to the steps G and subsequent steps. Similar to the method shown in FIG. 2, this method also makes it possible to reliably form an etching resist with a uniform film thickness, and also to reliably harden the etching resist on the inner wall of the through hole.

FIG. 4 shows an example of application of the manufacturing method according to the present invention.

A diffusely reflecting plate 6 is sandwiched between the first substrate I and the second substrate l'' as shown in the figure, and ultraviolet rays are irradiated onto the substrate from both above and below.Both the upper and lower surfaces of the diffusely reflecting plate 6 are composed of diffusely reflecting surfaces. In steps G and H in Fig. 2, the two substrates are exposed from both the top and bottom in a sandwich structure through the diffused reflection plate 6, thereby allowing simultaneous processing of the two substrates in one exposure step. Therefore, after completing this step, if the two substrates 1.1'' are exchanged upside down and exposed again, the exposure processing of the two substrates can be completed in two exposure steps. In other words, it can be considered that the exposure of one substrate is substantially completed in one exposure process, and the efficiency can be improved.

In the above embodiments, the photosensitive etching resist was formed on the circuit portion including the through holes by an electrodeposition coating method, but in the present invention, the photosensitive etching resist was formed in the circuit portion including the through holes in a state where the photosensitive etching resist was exposed. It is not necessarily necessary to use an electrodeposition coating method to form this etching resist. Of course, it is also possible to form the etching resist using other methods.

(Effects of the Invention As described above, according to the present invention, when the photosensitive etching resist formed exposed in the circuit portion including the through hole is exposed to light, it is exposed on one side of the substrate. Since a diffused reflection plate is placed for exposure, the light is diffusely reflected by the diffused reflection plate and reaches the photosensitive etching resist in the through-hole, so that the resist can be sufficiently irradiated with light. Therefore, peeling of the resist on the inner wall of the through hole due to insufficient exposure to light can be easily prevented, and there is an advantage that the reliability of the through hole can be surely improved.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the manufacturing method of the present invention. FIG. 2 is a diagram explaining the manufacturing method according to the present invention in the order of steps;
FIG. 3 is a diagram showing a modification thereof, and FIG. 4 is a diagram for explaining a method for performing the manufacturing method of the present invention more efficiently. FIG. 5 is a diagram for explaining a conventional manufacturing method. 1 - substrate, 2 - conductor section, 3 - etching resist, 4 - through hole, 6 - diffused reflection plate.

Claims (1)

[Claims] (1) After forming a conductor part on the entire surface of the board including the through holes, expose the photosensitive etching resist only on the circuit part including the through holes, then place a diffused reflection plate on one side of the board, and place the diffuser on the other side. A method for manufacturing a through-hole wiring board, characterized in that a step of exposing the entire surface to light is performed on both the upper and lower surfaces of the board, and a circuit pattern is formed by etching away conductor parts in areas other than the photo-cured etching resist area.