JPH0427184Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention relates to printed multilayer boards used in various electronic devices, and in particular, in order to connect the lower electrode and upper electrode provided above and below the insulating layer, This relates to the structure of via holes provided in layers.

<Prior art and problems> The basic structure of a printed multilayer board is as shown in Figures 3 and 4, in which a lower electrode 2 is provided on an alumina substrate 1, and an insulating layer 3 is screen printed on it. The upper electrode 4 is formed on the insulating layer 3 in a predetermined pattern, and the required number of insulating layers and electrodes are sequentially laminated on top of these. They are configured to be electrically connected through via holes 5 provided in the insulating layer 3.

From the viewpoint of reliability, the insulating layer 3 needs to be overlaid with insulating material at least two to three times by screen printing, and the via hole 5 provided in the insulating layer 3 is formed to have a small size of about 0.2 to 0.5 mm square. has been done.

Since screen printing is performed from a fixed printing direction, when forming the second insulating layer 3b on the first insulating layer 3a, in the via hole 5 part, the inner periphery of the first insulating layer 3a in front of the printing direction is There is a problem in that the insulating material bleeds 6 and the via hole 5 becomes blocked or narrowed, resulting in poor conduction between the upper and lower electrodes.

The occurrence of bleeding in the via hole 5 is caused by the ink being pushed in with a squeegee in the screen printing method when forming the second insulating layer 3b, which causes the thickness of the front end in the printing direction of the via hole of the first insulating layer 3a to be formed earlier. This is caused by the difference in level.

This idea was made in order to solve the above problems, and it is a printed multilayer that can suppress bleeding into via holes when forming an insulating layer and can obtain a reliable connection between upper and lower electrodes. The purpose is to provide a substrate.

<Means for solving the problem> This idea was made in order to solve the above problem. The via holes in the layer are formed in such a shape that they become larger toward the front side in the printing direction.

<Operation> After forming a first insulating layer on the lower electrode, a second insulating layer is formed thereon.

With respect to the via hole pattern provided in the first insulating layer, the via hole pattern in the second insulating layer is formed so that the front side in the printing direction is larger to prevent bleeding in the via holes in the second insulating layer due to the thickness of the first insulating layer. to ensure a secure connection between the upper and lower electrodes at the via hole.

<Example> Hereinafter, an example of this invention will be described based on FIGS. 1 and 2 of the accompanying drawings.

In each of these figures, the same parts as in the conventional example shown in FIGS. 3 and 4 are given the same reference numerals, and their explanation will be omitted.

As shown in the figure, in the via hole 5 provided in the insulating layer 3 to establish electrical conduction between the lower electrode 2 and the upper electrode 4, the via hole 5a provided in the first insulating layer 3a is formed in a predetermined shape necessary for electrical conduction.

On the other hand, the via hole 5b provided in the second insulating layer 3b has a shape that is, for example, about 0.05 to 0.2 mm larger than the via hole 5a in the first insulating layer 3a on the front side in the printing direction shown by arrow A in FIG. Form.

As a result, when forming the second insulating layer 3b by printing, the edge portion of the via hole 5b on the front side in the printing direction remains on the first insulating layer 3a, even if ink is pushed in with a squeegee in the screen printing method. , the bleeding of the previously formed first insulating layer 3a into the via hole 5a is suppressed.

Therefore, the via hole 5 is ensured to have a predetermined diameter,
Conductivity between the upper and lower electrodes 2 and 4 can be ensured.

<Effects> As described above, according to this invention, the via holes in the upper insulating layer are formed in a shape such that the front side in the printing direction of the insulating layer is larger than the via hole in the lowest insulating layer. Even if the ink is forced into the via hole part, the bleeding of the lowermost insulating layer formed earlier into the via hole is suppressed, and therefore a predetermined diameter can be secured in the via hole, and conduction between the upper and lower electrodes is ensured. connection reliability is greatly improved.

Furthermore, since a predetermined diameter can be secured without enlarging the entire via hole, it is possible to downsize the via hole design.

[Brief explanation of the drawing]

FIG. 1 is an enlarged longitudinal sectional view of a printed multilayer board according to this invention, and FIG. 2 is an enlarged perspective view showing the main parts of the same.
FIG. 3 is an enlarged vertical sectional view showing a conventional printed multilayer board, and FIG. 4 is a perspective view showing the main parts of the same. 2... Lower electrode, 3... Insulating layer, 4... Upper electrode, 5... Via hole.

Claims (1)

[Scope of utility model registration request] In a printed multilayer board in which a plurality of insulating layers are provided on a lower electrode by printing, and the upper electrode formed on the insulating layer and the lower electrode are electrically connected through a via hole provided in the insulating layer. A printed multilayer board, characterized in that the via holes provided in the insulating layer are formed in such a shape that the via holes in the upper insulating layer are larger toward the front side in the printing direction than the via holes in the lowest insulating layer.