JPH0352288A - Porcelain substrate - Google Patents

Abstract

PURPOSE:To made it possible to connect the electrodes on both sides of a substrate surely as well as prevent disconnection, by providing a substrate with through-holes whose diameters change with the distance from the surface of the substrate, and making through-holes having no edge sections. CONSTITUTION:The diameter of a through hole 2 at the surface and the back of a substrate 1 is made larger than that at the center section. On this occasion, as the pressure by vacuum becomes high at the center section of the thickness of the board 1, power which absorbs conductor material becomes strong and it creeps into the inside wall section of the through-hole 2 sufficiently. This makes it possible to obtain an effect that the connection of the electrodes on both sides of the substrate is surely performed. Besides, it becomes difficult for disconnection to occur as edge sections are obtuse surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a ceramic substrate made of alumina or the like having through holes provided for connecting circuits on the front and back sides of the substrate when forming an electronic circuit. It is.

BACKGROUND OF THE INVENTION Conventionally, through holes in ceramic substrates have had a constant hole diameter in the thickness direction of the substrate. Form conductive material on the front and back boards around this hole by screen printing, etc.
The opposite side to the printed side was placed in a vacuum, and conductive material was poured into the inner wall of the through hole to connect the circuits on the front and back sides. The inner wall of the hole was also flat with no irregularities.

Problems to be Solved by the Invention However, when printing connects circuits on the front and back sides of a board using through holes, if the degree of vacuum on the side opposite to the printed side becomes low, the force that attracts the conductive material from the opposite side will increase. It became weak and the tangent line inside the hole was incomplete, which could cause the circuit to break. Similar disconnections also occurred at the edge of the hole near the substrate surface.

Means for Solving the Problems In order to solve the above problems, the present invention changes the diameter of the through hole in the thickness direction of the substrate.

According to the above-described structure, the present invention can reliably connect circuits within the through-holes even when the degree of vacuum sucked on the side opposite to the printed surface of the board is low. It also has the effect of reducing disconnections at the edges of through holes.

Embodiments Hereinafter, embodiments of the present invention will be explained using the drawings of FIGS. 1 to 4.

Fig. 1 is a cross-sectional view of one embodiment of the present invention, Fig. 2 is a cross-sectional view of a state in which the conductive material for electrodes is printed in Fig. 1, and Figs. 3 and 4 are cross-sectional views of other embodiments. be.

FIG. 1 shows an embodiment in which the diameters of the through holes 2 on the front and back surfaces of the substrate 1 are larger than the diameters at the center in the thickness direction of the substrate 1. FIG. 2 is a diagram in which the electrode conductor material 3 is printed in the hole from the front and back sides, respectively.

Conventionally, the hole diameter was constant in the thickness direction of the board, so if the degree of vacuum on the side opposite to the printed surface was low during printing, the electrode conductor material printed on the board surface would be sufficient to cover the inner wall of the through hole. It didn't flow. In this embodiment, the vacuum pressure at the center of the board thickness is higher, so the force to attract the conductor material is stronger, and the conductor material is sufficiently wrapped around the inner wall of the through hole, ensuring a secure connection on both sides of the board. It will be done. Also, since the edge portion is an obtuse surface, it is difficult to break the wire.

FIG. 2 shows an embodiment in which the diameters of the through holes are different on the front and back surfaces of the substrate, and the same effect as in FIG. 1 is obtained.

Figure 4 shows the embodiment shown in Figure 1 with grooves 4 added.
When printing the electrode conductor material, the conductor material flows along these grooves 4, facilitating connection.

Effects of the Invention As described above, according to the present invention, it is possible to obtain the effect of reliably connecting the electrodes on both sides of the substrate, and also to prevent disconnection because the through hole has no edge portion.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a ceramic substrate according to an embodiment of the present invention, FIG. 2 is a sectional view showing the embodiment of FIG. 1 with electrode conductor material printed, and FIG. 3 is another embodiment of the present invention. FIGS. 4a and 4b are a cross-sectional view and a plan view of another embodiment of the present invention. 1... Board, 2... Through hole, 3
······groove. Figure 1 Figure 2 Figure 3 Figure 3/-1 Board 2 Figure 4 (a-4 Cb) 4

Claims (2)

[Claims] (1) A ceramic substrate characterized by having a through hole whose diameter changes in the thickness direction of the substrate. (2) The ceramic substrate according to claim 1, wherein a groove is provided on the inner wall of the through hole.