JPS6052589B2 - How to pin out a ceramic board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for pin-out of a ceramic substrate, more specifically, a method for providing connector pins for connecting a ceramic circuit board carrying a semiconductor element to a mother circuit board. Relating to a method for making holes in a board by laminating unfired ceramic green sheets with holes punched in them, metalizing the holes, and then soldering connector pins to the holes to take out the connector pins. .

Conventional methods for attaching connector pins to ceramic substrates include brazing one end of the connector pins to the back of the ceramic substrate, or drilling holes in a green sheet before firing to expose the connector pins. be.

FIG. 1 is an explanatory cross-sectional view showing an example of attaching a connector pin according to the prior art, in which one end of the connector pin is brazed to the back surface of a ceramic substrate.

On the left side of Figure A is shown a straight connector pin 6 that is brazed 3 into a hole in a board. Connector pin 6
Because they are inherently small, they have low resistance to lateral forces, so-called rolling and pulling forces. In order to improve this weak point, as shown on the right side of the same figure, the end (bottom in the figure) of the connector pin 6' is enlarged, and this enlarged end 9 is
A metallized 3' version was proposed. Indeed, such connector pins resist lateral and tensile forces, but
This requires extra area and is inappropriate when the number and density of contact pins required in the substrate for the connector 51 is large and high. Note that the hatched portions in FIG. 1 are brazed portions. Green sheet 1 before firing
An embodiment in which the connector pin 6'' is taken out by drilling a hole is shown in the cross-sectional explanatory view of FIG.

After drilling the hole as shown in the figure, the surface of the hole is metalized 3" and the connector pin 6" is fixed by brazing, thermocompression bonding, or welding.
There is a risk that circuit boards, which have become more complex due to miniaturization of circuit patterns, may be damaged during the drilling process. In addition, if the density of the connector pins becomes too high, it becomes difficult to bring out the pins to the back side of the circuit, and the connector pin 6'' shown in the figure has the disadvantage that it is vulnerable to being pushed up from below. in 4
is an IC chip, 5 is a lead, and 8 is an electrode. The present invention solves the above-mentioned problems experienced in the prior art, and is a technique for attaching connector pins to a ceramic substrate by using a ceramic green sheet in which holes for attaching connector pins are punched into a predetermined shape. The present invention relates to a method for forming pins by laminating layers.

Modern technology increases the complexity of multilayer circuit boards and increases the number of connector pins for their connections. As the density of multilayer substrates increases, it is desired to increase the density of connector pins, and the present invention is effective in achieving this objective. The method of the invention will now be explained with reference to embodiments of the accompanying drawings. FIG. 2 is a perspective view of four unfired ceramic green sheets 11 separated from each other.

A signal circuit pattern 17 is shown on the upper two green sheets. These patterns 17 are connected to an external circuit (not shown), for example, a mother circuit board.
Connector pins 16 as shown are used. The method of the present invention relates to a method for mounting such connector pins 16, so-called pin-out method. The number of green sheets is 4.
It is not limited to the number of sheets, and an appropriate number can be used as necessary. The signal circuit pattern 17 can be connected to the connector pin 16 through a via hole 18 shown in FIG. Such via holes are formed by the method disclosed in other patent applications filed concurrently with this application, but the circuit and via holes are formed in a green sheet,
The green sheets are laminated to form a ceramic multilayer circuit board, and conductors in the via holes are interconnected between layers by printing a conductive paste on the front and back sides of each green sheet so as to cover the via holes, Interlayer connections in multilayer circuits are made by forming lands of conductive paste around the via holes. Corresponding to the via holes 18, the two ceramic green sheets shown at the bottom of FIG. 2 are punched out to form holes 12.

The punching force does not need to be large because the green sheet is unfired, and a force of about 1k9/d is sufficient. FIG. 3 is an explanatory cross-sectional view showing the process of forming holes, and as shown in a of the figure, the green sheet 11
The surface and surrounding area of the hole 12 (both the top and bottom as seen in the figure) is metalized 13 with conductive paste.
In the illustrated embodiment, only the bottom two green sheets have holes formed by punching, and the third green sheet from the bottom has a stop 19 for the hole 12 formed with conductive paste. When the green sheets with holes 12 formed in this way are stacked and fired as described later, not only are holes 12 as shown in b in the same figure formed, but also as shown in the line rows on both sides of the holes. A metallized layer such as the one described above is formed by penetrating into the ceramic to improve the bond strength of the connector pin. The green sheets laminated and fired to form via holes and holes for connector pins become the ceramic substrate 15 shown in FIG. 4, which is a cross-sectional explanatory diagram showing the structure of the completed ceramic substrate 15. In the figure, horizontal lines indicate interlayer signal circuit patterns 17. To connect the ceramic substrate 15 to the outside, connector pins 16 shown in FIG. 5 are inserted into the holes 12 as shown. Soldering or brazing completes the so-called pinning.

In the illustrated embodiment, the connector pins 16 have a diameter of approximately 0.5 mm.
51! Although the diameter of the hole is set according to the diameter of the connector pin to be used. Since such a connector pin can be formed into a straight cylindrical shape without having to enlarge the end portion as in the conventional example, there is no need to particularly increase the spacing between the holes 12, which is effective for increasing the density of connections. It is. In the illustrated embodiment, the depth of all holes 12 is 1 m.
Depending on the circuit pattern, certain holes can be made deeper or shallower.

In other words, the depth of the hole 12 to the inside of the ceramic substrate 15 can be set freely, and the pins can be set out in any desired shape. As can be understood from the above explanation, according to the method of the present invention, since holes are formed in the green sheet, holes for connector pins are formed without damaging the multilayer circuit, so it is safe in terms of processing. The use of straight, thin connector pins allows for higher density connections, and the holes for connector pins can be made to any depth, increasing the freedom of forming connections. Since the pins are brazed, the bonding strength is high, and the holes are formed by an extremely easy process.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view showing the connection between a connector pin and a ceramic substrate according to the prior art, FIG. 2 is an exploded perspective view for explaining an embodiment of the present invention, and FIG. 3 is a hole for a connector pin according to the present invention. 4 is a sectional explanatory diagram showing the formation of a ceramic substrate according to the present invention, and FIG. 5 is a partially cutaway diagram of a ceramic substrate according to the present invention with connector pins attached. It is a cross-sectional explanatory diagram. 1,11...Ceramic Green sheet, 3
, 3″, 3″, 13...metalized part, 4...
IC chip, 5...Lead, 6,6'',62,
16... Connector pin, 8... Electrode, 9...
... Enlarged end, 12 ... Hole, 15 ...
... Ceramic board, 17... Signal circuit pattern,
18... Via hole, 19... Stop.

Claims (1)

[Claims] 1. In a method for attaching and drawing out connector pins for connection of ceramic circuit boards, the holes in the ceramic circuit board to which the connector pins are to be attached are formed by laminating and firing ceramic green sheets with holes punched in them. 1. A method for pin-out of a ceramic substrate, characterized in that the connector pin is attached to the pre-metallized hole.