JPS6354239B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a high-density circuit board on which elements such as ICs and LSIs are mounted, and more particularly to a method for manufacturing a multilayer ceramic substrate that provides means for forming conductor terminals for connecting the elements.

Ceramic substrates with compositions such as alumina ceramics have high mechanical strength, high thermal conductivity, and excellent electrical and chemical properties, so they are now widely used for mounting and assembling LSI chips with a large number of pins. It is used. The present invention is directed to such ceramic substrates, and relates to a so-called three-dimensional circuit-forming substrate in which 80 or more unfired ceramic substrates (so-called green sheets) are laminated and fired. It is an object of the present invention to provide a method by which conductor terminals can be formed.

Such multilayer ceramic substrates usually have via holes for conductive connections between several layers of laminated circuits, and externally exposed conductors for connecting functional elements (IC, LSI, etc.) to be mounted on each surface of the laminated body. It is common to provide a terminal. Conventionally, the via holes have been formed by press-fitting or filling metal conductor balls, and the interlayer connection circuits and external terminals have been formed by the following means.

That is, FIG. 1 is a sectional view showing how via holes are formed in a sheet body by the conductor ball press-fitting method. In the figure, 1 is a green sheet or a sheet, and 2 is an arrangement jig provided with through holes 6 for regulating the position of the via hole arrangement and for press-fitting the arranged conductor balls 5 with a press die 4. 3 in the figure is a receiving mold for the pressing mold 4. For details on via hole formation using such a press-fitting method, please refer to Japanese Patent Application No. 13011 (Showa 54).
(filed on October 9, 1954).

The lower part of FIG. 1 shows the single sheets 1 and 1' after the conductor balls have been press-fitted, and the front and back surfaces 7 of these sheets are shown.
and 8, a via hole is formed between the conductor 5 and a circuit in which a conductor circuit is formed by, for example, a mask pattern.
A plurality of these single sheets are positioned and stacked,
This is fired at a predetermined temperature to form a multilayer ceramic board, and the target conductor terminals can be formed by grinding the board edge (shaded area) after the firing and cutting it to the A-A index line position. I can do it. In other words, the ball conductor 5 located near the edge of the sheet is exposed and used as a terminal.

However, despite the high precision alignment between the ball arrangement jig (see Figures 2 and 10 in A of Figure 2) and the sheet body 1, the conductor corresponding to the terminal is spherical, and the side surface grinding that exposes the conductor is difficult. If the substrate holding jig and grinding conditions are uneven during the work, the terminal surfaces will vary between the upper and lower laminated substrates, which is inconvenient.
In the case of uneven grinding, the conductor is not exposed on the lower substrate 1' side as shown in the example diagram (the diagram is exaggerated to make the problem clearer).The purpose of the present invention is to eliminate the above-mentioned disadvantages. It is in. To achieve the object, the present invention includes a step of press-fitting a cylindrical conductor member into a green ceramic substrate so that the axis of the cylindrical conductor member and the surface of the green ceramic substrate are approximately parallel, and a step of laminating the green ceramic substrates. This method of manufacturing a multilayer ceramic substrate is characterized by comprising a step of pre-firing, and a step of exposing the columnar conductor member by grinding the side surface of the fired substrate.

An embodiment of the present invention will be explained below with reference to FIGS. 2 and 3, which illustrate one embodiment of the present invention. Fig. 2 is a perspective view and Fig.
The figure is a perspective view illustrating a grinding means for exposing terminals.

In Fig. 2, Fig. A shows the state before press-fitting, in which the ball conductors 5 are positioned within the frame using the arrangement jig 2 and the jig fixing frame 10 placed on the green sheet 1, and Fig. B shows the state before press-fitting, in which the ball conductors 5 are positioned within the frame. The state of the seat after the balls 5 are press-fitted into the seat 1 is shown. The size of the ball is, for example, about 0.34 mm in diameter, taking into account high-density wiring patterns and the like.

Figure C is a continuation of the process in Figure B, in which a cylindrical conductor as a terminal conductor, which is the essential part of the present invention, for example, an Au conductor with a diameter of 0.34 mm and a length of about 1 mm, is arranged and positioned by the frame 11 on the sheet 1 as in Figure A. Cylindrical conductor 1
2 is shown before being press-fitted. Figure D shows the conductors press-fitted by a hydraulic press device (not shown) at the time when the arrangement of the conductors 12 is completed on the four sides of the sheet. The arrangement of the conductors 5 and 12 is merely an example, and as shown in the figure, a large number of via hole forming portions are arranged in a high-density arrangement in the center of the sheet, and on the other hand, a large number of externally exposed conductor terminals are arranged on the outer side of the sheet. It will be established.

Figure 3 shows the sheet 13 that has undergone the step D in Figure 2.
FIG. 2 is a perspective view of a multilayer laminate 14 obtained by stacking a large number of the above-mentioned circuit patterned products 4 and pressurizing them to form a multilayer, and then firing in a furnace at 900°C.

Each side 15 to 19 of the laminate 14 (there are 5 sides)
is surface ground or surface polished to form a terminal with a cylindrical terminal conductor. For example, the figure shows a situation in which the conductor 2 is exposed on the side surface 15 of the substrate.
Of course, each of the other side surfaces 16 to 19 is also surface polished. Thus, the substrate body 1 excluding the bottom surface
All sides of 4 serve as mounting surfaces for functional elements that are exposed to the outside, and pad-shaped conductor terminals are formed within these surfaces. The arrangement example of the conductor terminals (the surface 15 shown in the figure is a DIP terminal configuration) is only one example. It is also possible, for example, to form conductor terminals for array terminals of flat pack construction.

According to the method for manufacturing a multilayer ceramic substrate according to the present invention as described above, the difficulty in grinding the side surface of the substrate due to the shape defect of the spherical conductor terminal is eliminated, and the workability during grinding is also improved, making manufacturing easier. As a result, an inexpensive ceramic substrate can be provided.

From this point of view, the industrial effects of the present invention are significant.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing a conventional ceramic substrate manufacturing method, and FIGS. 2 and 3 are perspective views for explaining the multilayer ceramic substrate manufacturing method according to the present invention, and perspective views as an example of the completed substrate. It is. In the figure, 1 is a sheet before firing, 3 and 4 are both press molds for press-fitting a conductor 5 such as a ball, 9 is a side surface of a substrate sheet, 12 is a cylindrical conductor, 13 is a completed sheet into which conductors 5 and 12 are press-fitted, 14 is a multilayer ceramic substrate body, and 15, 16, 17, 18 and 19 are side surfaces of the fired substrate.

Claims (1)

[Claims] 1. In a method for manufacturing a multilayer ceramic substrate having a plurality of via holes for conductor terminals and interlayer connections, a cylindrical conductor member is placed on an unfired ceramic substrate so that the axis of the cylindrical conductor member and the surface of the unfired ceramic substrate are approximately parallel to each other. A multilayer ceramic substrate comprising: a step of press-fitting the unfired ceramic substrates so that Production method.