JPS644356B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a circuit pattern on both sides of a substrate,
The present invention relates to a method of manufacturing a ceramic circuit board in which a connecting portion passing through the board is provided between the circuit patterns.

Conventionally, printed circuit (PC) boards have mainly been made of laminates made of organic materials such as Bakelite, glass, and epoxy with conductive layers attached, but in recent years, ceramic thin sheets such as alumina have been used as substrates. PC boards, which are formed by baking conductor patterns directly onto the surface, are also coming into use.

In addition, in response to increasingly complex circuit configurations, double-sided PC boards with conductor patterns on both the front and back sides are increasingly being used.
Ceramic PC boards that have many double-sided connection parts have come to be used.

Conventionally, the configuration of the double-sided connection portion in such a ceramic PC board has been adopted, for example, as shown in FIG. 1.

In the figure, 1 is a ceramic substrate, 2 is a through hole provided in a connecting portion, and 3 is a conductive pattern formed by baking a conductive paste or the like.

Such a connection is formed as follows. That is, at the same time as the conductive patterns 3 are printed on both sides of the substrate 1, the conductive paste is sucked into the holes 2 by a suitable suction means so that the conductive patterns 3' are also formed inside the holes 2. Thereafter, the entire structure is fired to print the conductor patterns 3, 3' onto the substrate 1.

According to the ceramic substrate having the double-sided connecting portions shown in FIG. 1, the thickness of the portion where the connecting portions are provided is kept approximately the same as the portion of the substrate having the conductor pattern, so electronic components can be mounted on the ceramic substrate. However, when printing the conductive pattern 3, special equipment such as a vacuum suction device is required, and the conductive material such as the conductive paste protrudes onto the suction side surface of the substrate 1 during suction, disturbing the pattern. There is a risk that
Moreover, since such protruding parts of the conductor material are formed, it is impossible to use a conveying method such as sliding feed, which is widely used in the manufacture of PC boards, making automation difficult. .

In addition, it is difficult to uniformly pour the conductive material into the inner surface of the connection hole 2, and it is also difficult to confirm this, making it difficult to obtain reliable products and resulting in poor yields.

Therefore, as the structure of the double-sided connecting portion in a ceramic substrate, the structure shown in FIG. 2 is also adopted.

In FIG. 2, 4 is a solder resist, 5 is a connection terminal, and 6 is solder.

That is, as is clear from FIG. 2, after forming a conductor pattern 3 on a ceramic substrate 1, a solder resist 4 is applied to the necessary portions, and connection holes 2 are formed.
There is a connection terminal 5 made of metal material such as copper inside.
The conductive pattern 3 and the terminal 5 are connected by the solder 6 by inserting the conductor pattern 3 and performing soldering using a solder bath or the like.

According to the connection part shown in FIG. 2, a reliable connection can always be obtained, but since the terminal 5 is inserted into the connection part and the connection is made by solder 6,
There was a drawback that electronic components could not be mounted on the portion where the connection portion was formed, and the area of the board therefore increased.

An object of the present invention is to provide a method for manufacturing a ceramic circuit board having double-sided connecting portions that is easy to manufacture, provides reliable connections, and can improve the degree of integration of electronic components, etc., while eliminating the drawbacks of the prior art described above. It is about providing.

In order to achieve this object, the present invention inserts a tablet made of the same cermet material as the conductor material for forming the conductor pattern into a through hole provided in the connection part, and the tablet and the conductor material are fired together. It is characterized in that the connecting portion is configured by:

Embodiments of the present invention will be described below with reference to FIGS. 3 to 5 of the drawings.

FIG. 3 shows an embodiment of the present invention, and 7 is a cermet tablet. In addition, the ceramic substrate 1, the through hole 2 provided in the double-sided connection part, and the conductor pattern 3
etc. are the same as the conventional examples shown in FIGS. 1 and 2.

The double-sided connecting portions of the ceramic circuit board shown in this embodiment are formed as follows. First, a ceramic substrate 1 made of alumina, forsterite, etc.
A hole 2 for double-sided connection is provided in the required part of the tablet, and a tablet 7 made of a cermet material made of silver (Ag), palladium (Pd), copper (Cu), tungsten (W), etc. is placed in this hole 2. insert. This tablet 7 is made by molding a powder of cermet material by an appropriate method, for example using a binder, and then drying it. Next, conductive patterns 3 necessary for forming a circuit network are printed with suitable conductive material on both sides of the substrate 1 so as to contact both end faces of these tablets 7. Thereafter, the ceramic substrate 1 having this connection part is fired at 800 to 1600°C to form the conductor pattern 3.
The tablet 7 is then sintered, and the connecting portion and the conductor pattern 3 are formed all at once.

In this way, the printed conductor pattern 3
Since both the cermet material and the tablet 7 are made of cermet material, they will be integrated when fired and sintered, so the conductor pattern 3 on both sides of the substrate 1 will not be completely mechanically bonded to the sintered cermet 7. , a complete electrical connection is obtained by the cermet 7.

It is extremely easy to make both end surfaces of the tablet 7 inserted into the hole 2 substantially flush with the front and back surfaces of the substrate 1. Therefore, when the conductive pattern 3 is printed using a conductive material, Since there is almost no possibility that the contact between the tablet 7 and the conductor pattern 3 will be insufficient, a reliable connection can always be obtained.

Further, even in the area where the connection part is formed by the tablet 7, the surface of the conductor pattern 3 is kept on the same plane as other parts, and there is no possibility that unevenness will occur on both sides of the substrate 1 due to the connection part.

FIG. 4 shows an embodiment in which an electronic component is mounted on a portion where a double-sided connection portion is formed by taking advantage of the features of the present invention.

In FIG. 4, 8 is a protective film for the conductive pattern 3 formed on the surface of the substrate 1, and 9 is an electronic component.

This electronic component 9 is attached by connecting its terminal portion to the conductive pattern 3 with solder 6. Incidentally, the through hole 2 and the tablet 7 are the same as those in the embodiment shown in FIG.

As in this embodiment, in the present invention, since the surface of the conductive pattern 3 on which the connecting portion is formed can be kept flat, it is not possible to provide the protective film 8 or to mount the electronic component 9 thereon. This makes it easy to increase the degree of integration and reduce the substrate area.

FIG. 5 shows still another embodiment of the present invention, in which multilayer wiring is applied to the double-sided connection portion.

In the figure, 10 is an insulating layer provided on the conductor pattern 3 in the portion where the double-sided connection portion of the tablet 7 is formed, and 11 is the upper conductor pattern. Note that the other details are the same as the embodiments shown in FIGS. 3 and 4.

According to this embodiment, multilayer wiring can be provided regardless of the presence of double-sided connecting portions, so that it is possible to reduce the size by increasing the degree of integration as in the embodiment shown in FIG.

As explained above, according to the present invention, it is possible to obtain a double-sided connection part of a ceramic substrate that can always make a reliable connection with a simple structure of inserting a tablet of cermet material into a hole in the substrate, which eliminates the drawbacks of the prior art. It is easy to automate the manufacturing process as there is no need for a vacuum suction device, etc., and it is also possible to mount electronic components on top of double-sided connections and form multilayer wiring, making it easy to downsize and have a high yield. A ceramic circuit board having double-sided connection parts can be provided at low cost.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are both cross-sectional views showing conventional examples of ceramic circuit boards having double-sided connection parts;
3, 4, and 5 are sectional views of ceramic circuit boards manufactured by each embodiment of the method of manufacturing a ceramic circuit board according to the present invention. DESCRIPTION OF SYMBOLS 1...Ceramic board, 2...Through hole provided in the double-sided connection part, 3, 11...Conductor pattern, 6...
Solder, 7... Cermet material tablet, 8...
...Protective film, 9...Electronic component, 10...Insulating layer.

Claims (1)

[Claims] 1. In a ceramic substrate for printed circuits having double-sided connecting parts, a tablet made of a cermet material such as silver-palladium, copper, or tungsten is inserted into a through hole in the ceramic substrate at a position where the double-sided connecting parts are to be formed. a step of filling the hole; a step of forming a circuit pattern using conductive paste made of the same cermet material as the tablet on both sides of the ceramic substrate including both end surfaces of the tablet inserted into the through hole; 1. A method for manufacturing a ceramic circuit board, comprising the step of collectively firing the formed ceramic substrate.