JPH06342983A - Multilayer circuit board - Google Patents

Abstract

PURPOSE:To enable a continuity between patterns of different layers without necessity of a plating step by putting a surface layer pattern, an inner layer pattern and the surface layer patterns in a continuity with conductive paste. CONSTITUTION:A surface layer pattern 1, an inner layer pattern 2, an inner layer pattern 3 and a surface layer pattern 4 are formed on both surfaces of boards 11, 12. Then, through holes 5a, 5b passed through the pattern 1, the board 11 and the pattern 2, and through holes 5c, 5d passed through the pattern 3, the board 12 and the pattern 4 are formed. The holes 5a-5d are filled with conductive pastes 7a-7d by printing, the boards 11, 12 are laminated by holding a prepreg material 17 at a center, and through holes 6a, 6b passing the entirety are formed. Then, conductive paste 8a is selectively filled in the hole 6a by printing, and the hole 6b remains as it is. The pastes 7a-7d and 8a protruding from the patterns 1, 4 are polished to the same plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board, and is particularly useful when applied to a board having a larger number of pattern layers.

[0002]

2. Description of the Related Art As the functions of electronic devices have become more sophisticated and complicated, it is necessary to increase the number of electrodes in one element and to combine a large number of elements in the same package. For this reason, in recent years, multilayer printed circuit boards have been promoted.

In a conventional multi-layer wiring board, when the surface layer pattern and the inner layer pattern are electrically connected,
When the patterns of different layers are made conductive, a through hole provided from the surface layer toward a predetermined layer is plated with a through hole to form a via hole (through hole for conduction only).

[0004]

As described above, in the prior art, since the conduction of the patterns of different layers is obtained by the via hole having the through hole plating,
A plating process is required in the manufacturing process of the multilayer wiring board. Since the equipment required for the plating process, especially the electric equipment, is bulky, not only the production equipment becomes large, but also the plating step is required, which complicates the process.

In view of the above-mentioned conventional technique, it is an object of the present invention to provide a multi-layer wiring board capable of conducting patterns of different layers without requiring a plating process.

[0006]

Means for Solving the Problems The structure of the present invention which achieves the above-mentioned object is a through-hole for ensuring continuity between a surface layer pattern, an inner layer pattern and a surface layer pattern in a multilayer wiring substrate having a pattern of three or more layers. The hole is filled with a conductive paste by printing.

[0007]

According to the present invention having the above-mentioned structure, the surface layer patterns are electrically connected to each other, and the surface layer pattern and the inner layer pattern are electrically connected by the conductive paste.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings.

As shown in FIG. 1, the multilayer wiring board I according to the present embodiment has surface layer patterns 1 and 4 and inner layer patterns 2 and 3.
The surface layer pattern 1 and the inner layer pattern 2 are conductive pastes 7a and 7b filled in the through holes 5a and 5b by printing, and the surface layer pattern 4 and the inner layer pattern 3 and the surface layer pattern 1, 4 are conductive pastes 7c, 7 filled in the through holes 5c, 5d, 6a in the same manner.
They are electrically connected by d and 8a. As the conductive pastes 7a to 7d and 8a at this time, silver palladium or copper paste is suitable.

FIG. 2 is a cross-sectional view showing an aspect of each step in manufacturing the multilayer wiring board I. A method of manufacturing the multilayer wiring board I will be described with reference to FIG.

As shown in FIG. 2A, the substrates 11 and 12 are
Conductive layers 13, 14, 15 and 16 are formed on both surfaces of. In the figure, 17 is a prepreg material.

As shown in FIG. 2B, the conductive layers 13, 1
Surface layer pattern 1, inner layer pattern 2, inner layer pattern 3 and surface layer pattern 4 are formed by respectively etching 4, 15 and 16 into predetermined patterns.

As shown in FIG. 2C, a through hole 5 penetrating the surface layer pattern 1, the substrate 11 and the inner layer pattern 2.
a, 5b and through holes 5c, 5d penetrating the inner layer pattern 3, the substrate 12 and the outer layer pattern 4 are formed.

As shown in FIG. 2D, the through holes 5a, 5
b and the through holes 5c and 5d are filled with the conductive pastes 7a and 7b and the conductive pastes 7c and 7d by printing. At this time, in this embodiment, all the through holes 5a to 5d are formed.
Although the conductive pastes 7a to 7d were filled in, the filling can be performed by appropriately selecting the through holes 5a to 5d.

As shown in FIG. 2 (e), the prepreg material 1
By sandwiching 7 in the center, the substrates 11 and 12 are laminated to form a four-layer multilayer wiring substrate.

As shown in FIG. 2 (f), through holes 6a, 6b penetrating the surface layer pattern 1, the substrate 11, the inner layer pattern 2, the prepreg material 17, the inner layer pattern 3, the substrate 12 and the surface layer pattern 4 are formed.

As shown in FIG. 2 (g), the through holes 6a are selectively filled with the conductive paste 8a by printing, and the through holes 6b are left as they are.

As shown in FIG. 2 (h), the conductive pastes 7a to 7d and 8a protruding from the surface layer patterns 1 and 4 are polished and processed so as to be flush with the surface layer patterns 1 and 4. That is, as shown in the enlarged view of FIG. 3A, the conductive pastes 7a to 7d and 8a protruding in the step of FIG. 2G are shown in the enlarged view of FIG. 3B. Grind flush in the step 2 (h). This is for the convenience of soldering an electronic component or forming a land on the conductive pastes 7a to 7d and 8a. In this case, as shown in an enlarged view in FIG. 3 (c), printing is performed in a size larger than the through holes 5a to 5d and 6a.
In the step (g), the conductive pastes 7a to 7d and 8a further protruding from the both ends of the through holes 5a to 5d and 6a on the surface are enlarged as shown in FIG. It may be ground flush with.

Finally, the conductive pastes 7a to 7d and 8a are hardened by heat. Thus, the surface layer pattern 1 and the inner layer pattern 2, the surface layer pattern 4, the inner layer pattern 3 and the surface layer patterns 1 and 4 are conducted by the conductive pastes 7a to 7d and 8a. When the blackening treatment is performed in the laminating step shown in FIG. 2E, the surface layer patterns 1 and 4 are blackened and peeled. The blackening treatment is a treatment for disturbing the surface in order to improve the adhesiveness with the prepreg material 17.

[0020]

As described above in detail with reference to the embodiments, according to the present invention, the plating process can be eliminated, and the conduction between layers can be established only by the printing process. It can be simplified and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an aspect of each step in manufacturing the above-mentioned embodiment.

FIG. 3 is an enlarged sectional view showing an enlarged part of FIGS. 2 (g) and 2 (h).

[Explanation of symbols]

 1,4 Surface layer pattern 2,3 Inner layer pattern 5a, 5b, 5c, 5d, 6a, 6b Through hole 7a, 7b, 7c, 7d, 8a Conductive paste

Claims (1)

[Claims] 1. A multilayer wiring board having a pattern of three or more layers, wherein a through hole for ensuring continuity between the surface layer pattern, the inner layer pattern and the surface layer pattern is filled with a conductive paste by printing. Multilayer wiring board.