JPS5836500B2 - Manufacturing method of ceramic substrate for IC - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic substrate and its manufacture, and mainly relates to a ceramic substrate having a heat dissipating member for a semiconductor integrated circuit device (IC).
Targeting the manufacturing of ceramic substrates for

As a ceramic substrate with good heat dissipation properties for a semiconductor integrated circuit device (IC), a heat sink (heat dissipation member) made of a copper metal plate is generally fixed on the top surface of a ceramic substrate mainly composed of alumina, and a semiconductor pellet is placed on the top surface of the ceramic substrate. Alternatively, a recess is formed in the ceramic substrate, a copper metal plate is fixed to the top surface of the Kovar plate (also known as a Kovar plate), and the semiconductor is fixed to the bottom of the recess. Structures for fixing pellets are known.

In the former case, since a copper metal plate is simply fixed to a ceramic substrate containing alumina as a main component, it is inexpensive, but on the other hand, heat dissipation characteristics are poor because heat is radiated to the outside of the substrate via the ceramic substrate.

In the latter case, the metal plate for heat dissipation is exposed to the outside of the ceramic board, so it has good heat dissipation properties, but it is expensive because it requires forming a recess in the ceramic board and inserting and fixing the Kovar plate and copper metal plate. There are drawbacks.

In any of the above cases, a copper metal plate must be provided separately after firing the ceramic substrate, which may increase manufacturing man-hours, manufacturing costs, and material costs.

Therefore, the inventor of the present application has proposed that if a large through hole is formed at the pellet fixing part of a ceramic substrate containing alumina as a main component, and the high melting point metal paste is filled into this hole and fired, it can be fired in one time. The inventors have thought that it is possible to form a ceramic substrate having a heat sink made of a high-melting-point metal, and that it is possible to relatively easily manufacture an inexpensive ceramic substrate with good heat dissipation characteristics.

However, in this case, since there is a significant difference in the coefficient of thermal expansion between the ceramic plate and the high melting point metal body, there is a problem that cracks occur in the 7-rank board after firing.

Therefore, the present invention has been made to solve such problems, and one purpose thereof is to obtain a ceramic substrate for IC with excellent heat dissipation characteristics with a small number of man-hours.Another purpose of the present invention is It is a further object of the present invention to prevent cracks from occurring in a 7-rank board for use in ICs.
The purpose of the present invention is to provide a ceramic substrate for use.

The gist of the present invention to achieve the above object is to selectively form a through hole in the IC pellet mounting portion of an unsintered ceramic substrate, and fill the through hole with a high melting point metal. Manufacturing a ceramic substrate for IC, characterized in that a high melting point metal layer for wiring and a high melting point metal layer for heat dissipation are formed on the back surface of the ceramic substrate in the vicinity of the IC pellet mounting portion, and then the substrate is fired. It's in the method.

An embodiment of the present invention will be specifically described below with reference to the drawings.

FIG. 1a shows a ceramic substrate of the present invention.

In the figure, reference numeral 1 denotes a ceramic substrate mainly composed of alumina, and a wiring layer 2 made of a metallized layer of a high melting point metal such as tungsten or molybdenum is formed on the upper main surface of this substrate, and on the lower main surface of this substrate. A conductor layer 3 made of a metallized layer of a high melting point metal is formed.

4 is a heat sink, which is made up of columns of high-melting metal such as tungsten or molybdenum embedded in the pellet fixing part of the ceramic substrate.

The upper part of this heat sink is connected to a wiring layer 2 for fixing pellets formed on the upper main surface of the ceramic substrate, and the lower part is connected to a conductor layer 3 formed on the lower surface of the ceramic substrate. .

Note that each high melting point metal pillar of the heat sink is made of a pillar with a diameter of about 1φ.

FIG. 1b shows a state in which semiconductor pellets are attached to the ceramic substrate of the present invention.

The semiconductor pellet 5 is plated with Ni on the surface of the wiring layer 2 for fixing the pellet, and is attached thereon via silver solder.

Thereafter, wires 6 are used to connect each electrode of the semiconductor pellet to the corresponding wiring.

According to the present invention as described in the embodiments above, since the ceramic substrate is provided with a heat sink consisting of a group of high-melting point metal columns, the heat generated from the semiconductor pellet can be dissipated to the outside of the ceramic substrate through each metal column. This makes it possible to provide a ceramic substrate with substantially the same effect as fixing semiconductor pellets on the top surface of a metal plate, and with excellent heat dissipation properties.

Next, the ceramic substrate manufacturing method of the present invention will be specifically explained.

As shown in FIG. 2a, a green ceramic plate (unfired ceramic plate) 1 whose main component is alumina is prepared, and a large number of through holes 7 are formed in the pellet fixing part by pressing or the like.

Each through-hole is 1,525 holes or less, and the number of holes formed in the pellet fixing part is such that the total area of the upper surface of the holes is 50 or less than that of the ceramic plate of the pellet fixing part. Make sure to close it.

b Print and coat a high melting point metal paste such as tungsten or molybdenum on the top surface of the green ceramic board, and at the same time vacuum the bottom of the board to form the wiring layer 2 on the top surface of the green ceramic board, and fill each through hole 1 with the above-mentioned height. Fill with melting point metal paste.

After drying the paste, the high melting point metal paste is also printed on the back surface of the ceramic plate to form a conductor layer 3.

After drying the paste, apply the above ceramic plate to 1300~160
After baking in a reducing atmosphere at 0°C, a wiring layer 2 made of metallized metal is formed on the upper surface, a conductor layer 3 made of metallized metal is formed on the lower surface, and metalized metal is formed on the pellet fixing part as shown in FIG. 1a. A ceramic substrate provided with a heat sink 4 consisting of a group of columns (a group of high melting point metal columns) is manufactured.

According to the present invention as explained above in the embodiments, a large number of through holes are formed in the pellet mounting portion of the ceramic substrate, and the substrate is fired with the high melting point metal filled in the holes, so that the ceramic substrate can be fired at once. A ceramic substrate having a heat sink made of a group of high-melting point metal columns can be manufactured in a single operation, and a ceramic substrate with excellent heat dissipation characteristics can be manufactured with a small number of man-hours.

Since a ceramic substrate with a heat sink consisting of a group of high-melting point metal columns is formed by firing a large number of through-holes formed in a splintered ceramic substrate and filled with a high-melting point metal, it is possible to compare the whole ceramic substrate. The proportion of each high melting point metal part is small.

Therefore, even if there is a significant difference in coefficient of thermal expansion between the ceramic plate and the high melting point metal, cracks will not occur in the ceramic substrate after the substrate is fired.

FIG. 3 shows another embodiment of the invention.

As shown in the figure, a group of high melting point metal columns such as tungsten and molybdenum are arranged in two stages, and a ceramic substrate having a heat sink is formed from the two stages of high melting point metal columns.

In this way, the area of the heat dissipating metal body becomes smaller and the heat dissipation performance becomes better.

Note that the present invention is not limited to the embodiments described above, and in manufacturing a ceramic substrate, a large number of through holes are formed in the pellet fixing part of a green ceramic substrate, the substrate is once fired, and then the through holes are formed. filled with high melting point metal and refired here? A lamic substrate may also be manufactured.

The present invention is primarily applicable to ceramic substrates for ICs and their manufacture, but is also applicable to other general 7-rank substrates for semiconductor devices that require heat dissipation and their manufacture.

[Brief Description of the Drawings] Figure 1a is a cross-sectional view of an embodiment of the present invention, Figure 1b is a cross-sectional view of a semiconductor pellet attached to a ceramic substrate of the present invention, and Figure 2 is a process diagram of the method of the present invention. Shown in order, a-b
3 is a sectional view of each step, and FIG. 3 is a sectional view of another embodiment of the present invention. 1... Ceramic substrate (board), 2... Wiring layer, 3...
... Conductor layer, 4... Heat sink, 5... Semiconductor pellet, 6... Wire, 7... Through hole.

Claims (1)

[Claims] 1. A through hole is selectively formed in the IC pellet mounting portion of the unsintered ceramic substrate, and the through hole is filled with a high melting point metal, and a high melting point metal layer for wiring and the above ceramic are filled in the vicinity of the IC pellet mounting portion. A method of manufacturing a ceramic substrate for IC, which is characterized by forming a high melting point metal layer for heat dissipation on the back surface of the substrate, and then firing the substrate.