JPS6243199A - 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] 1 Industrial application field 1 The present invention relates to a method for manufacturing a printed wiring board.

[Prior art 1] Conventionally, as a method for connecting circuit patterns formed on both sides of an insulating substrate, a conductive hole that penetrates both sides is provided at the center of a land in the circuit pattern on both sides, and a conductive material is placed in the conductive hole. A well-known method is described in Japanese Patent Publication No. Sho 56-15158, in which connection is made through the conductive material by filling the conductive material.

I Problems to be Solved by the Invention According to the method described in Japanese Patent Publication No. 56-15158, as shown in FIG. After applying the insulating liquid WI6.7 of solder resist to the pattern surface, leaving the land portion 4.5 and the surrounding areas where the double-sided conductive holes are to be formed, the conductive holes 8 are drilled or punched, and the seventh As shown in the figure, the conductive hole 8 is filled with a conductive substance 9 made of conductive paint, and the circuit patterns 1 and 2 on both sides are connected.

However, since the conductive hole 8 formed by drilling or punching has a substantially perpendicular cross section at the opening edges 4a and 5a including the land 4.5, the conductive material 9 is formed through the conductive hole. Conventionally, a bottle method or a silk screen method has been adopted as the filling method for filling the conductive material 9 into the conductive hole 8. It causes uneven filling and has problems with the accuracy of conduction rotation.

Further, after filling the conductive material 9 into the conductive hole 8 and completing the conduction,
When electronic components (not shown) are incorporated into the printed wiring 10, if the insulating substrate 10 is immersed in a melted solder bath, the temperature of the solder melting bath is as high as 240-260°C.
Based on the difference in material between the conductive material 9 and the lands 4 and 5, the difference in thermal expansion causes the conductive material 9 in the conductive hole 8 to
In particular, cracks occur at the boundaries between the lands 4 and 5 and the insulating substrate 3 due to strain.

Therefore, the reliability of the printed wiring board 10 itself is impaired due to the occurrence of both of the above-mentioned problems.

Therefore, the present invention has been made by focusing on the problems in this type of printed wiring board, and is intended to prevent uneven filling of the conductive material into the conductive holes and the occurrence of cracks in the conductive material 9 in a solder bath or the like. The purpose of this invention is to provide a highly reliable printed wiring board of this type.

[Means for Solving the Problems] In the method for manufacturing a printed wiring board of the present invention, when forming a desired circuit pattern on one or both sides of an insulating substrate, the diameter of the land hole of the land in the circuit pattern is adjusted. By positioning the land in advance at the center of the land and forming the land to have a diameter larger than the diameter of the conductive hole passing through it, and by positioning it at the center of the land hole of the land in the circuit pattern and passing through the conductive hole,
A method for manufacturing a printed wiring board, comprising the steps of: forming a step between the inner peripheral edges of the land hole of the land in the circuit pattern; and filling the conductive hole with a conductive material.

1 Effect J The method for manufacturing a printed wiring board of the present invention includes dust particles when filling the conductive material into the conductive hole, and a stepped portion provided between the inner periphery of the land hole of the land and the opening edge of the conductive hole. The stepped portion facilitates the inflow of the conductive material and alleviates the effect of thermal strain occurring between the insulating substrate and the land on the conductive material, thereby preventing the occurrence of cracks in the conductive material filled in the conductive hole.

[Example] Hereinafter, an example of the method for manufacturing a printed wiring board of the present invention will be described [J] with reference to the drawings.

: Figure 51 is a partially enlarged plan view showing a printed wiring board manufactured by the manufacturing method of the present invention, Figure 2 is a cross-sectional view taken along the line A-A in Figure 1, and Figure 3 is a state in which the through hole is filled with a filler material. FIG.

20 in the figure is an insulating substrate, and both sides 2 of this insulating substrate 20 are
0a and 20b each have the required circuit pattern 21.2.
2 is formed. Regarding the circuit patterns 21 and 22, only the lands 23 and 24 in each of the circuit patterns 21 and 22 are shown enlarged in the figure.

In addition, each circuit pattern 2 on both sides 20a and 20b
1.22 In order to electrically connect each other, the land holes 25 and 26 of the corresponding lands 23 and 24 are positioned at the center of the land holes 25 and 26, and the conductive holes 27 are passed through them.

Furthermore, when the lands 23, 24 are provided with land holes 25, 26 and the conductive holes 27 are passed through the centers thereof, the diameters of the land holes 25, 26, in particular! ; By making L1 a larger diameter than the sutra of the conduction hole 27, the land 23.
24 and the opening edge 27 of the conduction hole 27.
a.

A stepped portion 28 and 29 is provided between 27b and 27b.

In order to conduct the circuits on both sides of the printed wiring board 30 having such a structure, the conductive material 31 made of conductive paint is filled into the conductive holes 27 as shown in FIG. It is electrically connected via.

In the figure, reference numeral 32 indicates an insulating coating of solder resist, and although not shown, the conductive material 31 is overcoated with epoxy resin or the like to provide an insulating exterior.

FIGS. 4a to 4f are process diagrams showing an embodiment of the method for manufacturing a printed wiring board of the present invention.

Below is a printed wiring board 30 according to the steps shown in FIG. 4 a-f.
The manufacturing method will be explained.

40 is a double-sided copper-clad laminate (FIG. 4a) in which copper foils 42 and 43 are arranged on both sides of an insulating substrate 41.

Thereafter, as shown in FIG. 4, a pattern resist 45, 46 corresponding to the circuit pattern is applied to the copper foils 42 and 43 of the copper-clad laminate 40, and etching is performed thereon as shown in FIG. 4C. Then, circuits are formed on both sides of the insulating substrate 41.

Figures 4 and 4c show only the case where lands 47 and 48 are formed in the double-sided circuit pattern.

When etching is performed under the condition of printing the coating film 45 and 46 patterns shown in Fig. 4, especially the fourth
As shown in Figure C, the land 47 formed after etching
．． The etching resist coating 45 is applied to the land hole 49 of 48 and the passage of the conductive hole 44 that penetrates through the center of the land hole 49.50 in the subsequent process. .46.By etching this, land 4 shown in Fig. 4C is formed.
7. After forming the land hole 4, as shown in Fig. 4d,
9.50 and pass through the through hole 44 (Kyobun) by punching or drilling, thereby creating a gap between the inner peripheral edge of the land hole 49.50 of the land 47 and the opening edge of the through hole 44. Step portions 51 and 52 can be formed in the steps.

Thereafter, an insulating coating 53.54 of solder resist is applied to the lands 47.48, leaving the conductive portions (FIG. 4e), and the conductive holes 44 are filled with a conductive material 55, thereby forming the lands 47.48 with the same conductive material. A printed wiring board 60 can be formed by establishing conduction through the connector 55.

In the step shown in FIG. 4, after filling the conductive material 55 shown in FIG. In Figure 0, which shows an example of this, 56° and 57 are through holes, and 58 is a land.

Therefore, when the conductive material 31 is filled into the conductive hole 27 by the conventional bottle method or silk screen method, the inner peripheral edges 23a, 24a of the lands 23.24 and the conductive hole 2
7 opening edge 27a.

The stepped portions 28 and 29 provided between the conductive material 31 not only act as a guide but also serve as a reservoir for the conductive material 31.
Conductive material 31 into 27 conductive holes in conventional filling method
It is possible to eliminate the problem of filling L and burrs at once, stabilize the filling accuracy, eliminate conduction defects, and improve the quality of the product.

Further, when the printed wiring board 30 is immersed in a solder bath to attach electronic components (not shown) to the circuit patterns 21 and 22 on both sides after filling with the conductive material 31,
Even if a difference in thermal expansion occurs between the insulating substrate 20 and the lands 23 and 24 and distortion occurs between them, the effect of this on the conductive material 31 is alleviated by the stepped portions 28 and 29, and the conductive material 3
This can prevent the occurrence of cracks in 1.

[Advantageous Effects of the Invention 1] According to the present invention, it is possible to improve the reliability of a circuit configuration that conducts circuits between both surfaces by filling the conductive holes in a printed wiring board with a conductive material, and to improve the uniformity of quality.

[Brief explanation of drawings]

FIG. 1 is a partially enlarged plan view of a printed wiring board manufactured according to the present invention, FIG. 2 is a sectional view taken along line A-A in FIG.
The figure is a cross-sectional view of the conductive hole filled with a conductive material, Figure 4 a-f
5 is a process diagram showing an embodiment of the method for manufacturing a printed wiring board of the present invention, FIG. 5 is a sectional view of the printed wiring board after processing such as general hole processing, and FIGS. 6 and 7 are diagrams of a conventional printed wiring board. FIG. 3 is an enlarged sectional view showing the configuration. 30.60...Printed wiring board 20.41...Insulating substrate 21.22...Circuit pattern 23.24, 47.48...Land 24.26, 49.50...Land hole 27. 44...
・Conduction holes 28.29, 51.52...Stepped portions 31.55...4 electric material Patent applicant Japan CMK Co., Ltd. Agent Patent attorney Takeshi Nara 4 (a) n (c) (e) (d) (f)

Claims (2)

[Claims] (1) When forming a required circuit pattern on one or both sides of an insulating substrate, the diameter of the land hole of the land in the circuit pattern is positioned in advance at the center of the land, and the diameter is larger than the diameter of the through hole. and forming a step between the inner peripheral edges of the land hole of the land in the circuit pattern by positioning it at the center of the land hole of the land in the circuit pattern and passing through the conduction hole. A method for manufacturing a printed wiring board, comprising the step of filling the conductive hole with a conductive material. (2) The step of forming the stepped portion is formed in conjunction with the step of forming the circuit pattern of the copper-clad laminate by etching. Production method.