JPS6226887A - 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] [Industrial application field] The present invention relates to printed wiring boards.

[Prior Art] 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 inserted into the conductive hole. By filling ′! ! J. The method of connecting through the conductive material was published in Japanese Patent Publication No. 56-1515.
It is described in Japanese Patent Application No. 8 and is publicly known.

[Problem 1 that Patent Publication No. 13 attempts to solve 1 However, according to the method described in the above-mentioned Japanese Patent Publication No. 56-15158, land portions are formed on the circuit pattern surface of the insulating substrate 3 on which the pattern 1.2 is formed on one or both sides. 4, 5 and the surrounding areas where the double-sided conductive holes are to be formed, an insulating coating 6.7 of the exposed resist is provided, and then the conductive holes 8 are drilled by drilling or punching, as shown in Fig. 8. The conductive hole 8 is filled with a conductive substance 9 made of conductive paint, and the circuit patterns 1.2 on both sides are connected.

However, since the through hole 8 formed by drilling or punching has the opening edges 4a and 5a including the runt 4.5 having a substantially right-angled cross section,
When filling the conductive material 9 into the conductive hole 8, a bottle method or a silk screen method is conventionally adopted as the filling method. Conductive material 9 to be filled
This causes uneven filling, and there is a problem with the accuracy of conduction performance.

Further, after filling the conductive material 9 into the conductive hole 8 and completing the conduction,
When an electric component (not shown) is assembled into this printed wiring 10, if it is bonded in a molten solder bath, the temperature of the solder melting bath is as high as 240 to 260'0, so the insulating substrate 3 and the conductive material 9 Alternatively, due to the difference in thermal expansion based on the difference in material between the lands 4 and 5, the conductive material 9 in the through hole 8
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 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 Problem E] The printed wiring board of the present invention is a printed wiring board having a conductive hole penetrating both sides of the insulating substrate at the center of a land provided in a circuit pattern on one or both sides of the insulating substrate. , a stepped portion is provided between the inner peripheral edge of the land and the opening edge of the conductive hole.

[Function] In the printed wiring board of the present invention, the stepped portion provided between the inner peripheral edge of the land hole of the land and the opening edge of the conductive hole facilitates the inflow of the conductive material during filling into the conductive hole, and the conductive material The stepped portion alleviates the influence of thermal strain occurring between the insulating substrate and the land, and prevents cracks from occurring in the conductive material filled in the through hole.

[Example 1] Hereinafter, an example of the printed wiring board of the present invention will be described with reference to the drawings.

(First Embodiment) Fig. 1 is a partially enlarged plan view showing the first embodiment of the printed wiring board of the present invention, Fig. 2 is a sectional view taken along the line A-A in Fig. 1, and Fig. 3 is a filling in the conductive hole. FIG. 3 is a cross-sectional view of a state filled with a substance.

20 is an insulating substrate, and both surfaces 20a, 20 of this insulating substrate 20
Required circuit patterns 21 and 22 are formed on the respective portions b. Regarding one circuit pattern 21.22, the land 23.22 in each circuit pattern 21.22 in the figure.
Only 24 is shown enlarged.

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 land holes 25.26 are provided in the lands 23.24 and a through hole 27 is passed through the center of the land holes 25.26, in particular, the sutra 1 of the land holes 25.
By making the sutra larger in diameter, land 23.24
inner peripheral edges 23a, 24a and an opening edge 27a of the conduction hole 27.

Step portions 28 and 29 are provided between 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 Figure 1, reference numeral 32 indicates an insulating sheath of solder resist, and although not shown, the conductive material 31 is coated with an epoxy resin or the like to provide an insulating sheath.

Therefore, when the conductive material 31 is filled into the conductive hole 27 using the conventional pin 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 step portions 28 and 29 provided between the steps 27b not only act as a guide but also act as a reservoir for the conductive material 31,
Conductive substance 31 into conductive hole 27 in conventional filling method
It is possible to eliminate uneven filling at once, stabilize filling accuracy, eliminate conduction defects, and improve product quality.

After filling with the conductive material 31, electronic components (not shown) are attached to the circuit patterns 21 and 22 on both sides of the bath. Even if a difference in thermal expansion occurs between the two and strain occurs between the two, the conductive material 3 due to this
1 can be alleviated by the step portions 2B and 29, and the generation of cracks in the conductive material 31 can be prevented.

(Second Embodiment) FIGS. 4a to 4f show a method of manufacturing the printed wiring board 30 shown in the first embodiment.

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

Reference numeral 40 denotes a double-sided copper-clad laminate (Fig. 4a) in which copper foils 42 and 43 are placed on both sides of an insulating substrate 41. Alternatively, it can be penetrated by punching (Fig. 4b).

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

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

When etching is performed on the coated film 45.46/per unit printing condition shown in FIG.

By performing side etching on the side 44b, as shown in FIG. The step portions 51 and 52 can be formed between the inner peripheral edge of the land hole 49.50 of the land 47.44 and the opening edge of the conduction hole 44.

After that, the insulating liquid 11Q 53 and 54 of Tsuruta Resist is applied, leaving the conductive parts of the lands 47 and 48 (Fig. 4 e).
At the same time, a printed wiring board 60 can be formed by filling conductive material 55 into the conductive hole 44 and making the lands 47 and 48 conductive through the conductive material 55.

In the process shown in Figure 4, after filling the conductive material 55 shown in Figure 4f, other machining processes such as -diameter machining or outer diameter machining are performed, as shown in Figure 5. An example is shown below. In the figure, 56° and 57 are through holes, and 58 is a land.

According to this embodiment, the steps 51 and 52 are formed by side etching, which has the advantage that they can be processed in conjunction with the etching of the circuit pattern.

(Third Embodiment) Figures 6a to 6f show the third
It is a process diagram of an example.

As shown in FIG. 6C, the manufacturing method in this embodiment is to apply the pattern resist by resist printing necessary to form the stepped portions 51, 52 when performing the resist printing necessary for etching the lands 47, 48. a membrane 45.4
6. That is, the opening edge 4 of the conduction hole 44
4a.

44 b (7) Paint film 4 so that the outer periphery can be etched.
5.46 inner peripheral edges 45a, 46a are opening edges 44a, 44
Resist printing is performed by shifting the distance necessary to form the stepped portions 51 and 52 from the outer periphery of b.

Since the other methods are the same as those in the second embodiment, the explanation will be omitted, and the same parts in the process of forming the printed wiring board 60 are given the same numbers.

According to this embodiment, the step portions 51 and 52 can be formed simultaneously by etching the circuit pattern.
It can be manufactured without requiring the same extra steps as conventional printed wiring boards.

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

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged f-plane view of the printed wiring board of the present invention, and FIG.
The figures are a sectional view taken along the line A-A in FIG. 1, FIG. 3 is a sectional view of the conductive hole filled with a conductive material, FIGS. are cross-sectional views of the printed wiring board after processing such as general hole processing, and are shown in Figure 6 a to ft-.
FIG. 4 is a process diagram showing a different manufacturing method, and FIGS. 7 and 8 are enlarged sectional views showing the structure of a conventional printed wiring board. 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...
・Conducting holes 28.29, 51.52...Stepped portion 31.55...Conductive material No. 4 4J (C) (e) 'l) 4 '1) LJ Col 4zu Co4 (b) ( d' (f) 6th (c') (e) Figure (b) (d) (f)

Claims (5)

[Claims] (1) In a printed wiring board having a conductive hole penetrating both sides of the insulating substrate at the center of a land provided in a circuit pattern on one or both sides of the insulating substrate, there is a gap between the inner peripheral edge of the land and the opening edge of the conductive hole. A printed wiring board characterized in that it is configured by providing a stepped portion. (2) The printed wiring board according to claim 1, wherein the step portion is formed by providing a land hole in the land, the land hole having an inner diameter larger than the diameter of the conduction hole. (3) The printed wiring board according to claim 1, wherein the stepped portion is formed by side etching in the land pattern forming step after processing the conductive hole. (4) The stepped portion is formed by forming a land hole having a diameter larger than the diameter of the conductive hole in advance when forming the land, and then forming the land hole that penetrates both sides of the insulating substrate into the land hole portion of the land. The printed wiring board according to claim 1, characterized in that the printed wiring board is constructed by providing a conduction hole having a diameter smaller than that of the conductive hole. (5) The printed wiring board according to claim 1, wherein the conductive hole is filled with a conductive material to establish conduction between both surfaces of the insulating substrate.