JP2002246717A - Ceramic circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of electrical connection not being made sure and rigid between metal circuit boards bonded to the upper and lower surfaces of a ceramic substrate. SOLUTION: Metal circuit boards 3 of copper or aluminum are fixed to the opposite sides of a ceramic substrate 1, having a through-hole 4 such that the through-hole 4 is plugged and a metal post 5 of copper or aluminum is disposed in the through hole 4, in order to connect the metal circuit boards 3 on the opposite sides of the ceramic substrate. In such a ceramic circuit board, a space of 30-200 μm long is provided between the inner wall face of the through-hole 4 and the outer wall face of the metal post 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic circuit board having metal circuit boards attached to both sides of a ceramic substrate.

[0002]

2. Description of the Related Art In recent years, as a circuit board such as a power module board or a switching module board, a metallized metal layer adhered on a ceramic substrate is formed of a metal made of copper or the like via a brazing material such as a silver-copper alloy. A ceramic circuit board with circuit boards joined together, and a metal circuit board made of copper etc. directly joined on the ceramic substrate via an active metal brazing material obtained by adding titanium, zirconium, hafnium or its hydride to a silver-copper eutectic alloy A so-called DBC (D) in which a copper plate is placed on a ceramic circuit board or a ceramic substrate that has been heated and then directly bonded to the ceramic substrate and the copper plate.
A ceramic circuit board manufactured by an direct bond copper method is used.

In order to increase the mounting density of the metal circuit boards, these ceramic circuit boards are bonded to the upper and lower surfaces of the ceramic substrate, and the upper and lower surfaces of the metal circuit boards are provided on the ceramic substrate. An electrical connection is made with a brazing filler material filled in the through hole.

[0004] The ceramic circuit board, for example,
A ceramic circuit board in which a metal circuit board made of copper or the like is joined to a metallized metal layer adhered on a ceramic substrate via a brazing material is generally made of an aluminum oxide sintered body, an aluminum nitride sintered body, or a silicon nitride. Made of an electrically insulating ceramic material such as a porous sintered body, a mullite sintered body, etc.
A ceramic substrate having a predetermined pattern of metallized metal layers on both upper and lower surfaces and having a through hole penetrating in the thickness direction is prepared. Then, silver brazing powder (an alloy of silver and copper) is provided in the through hole of the ceramic substrate. Powder) with an organic solvent, a brazing material paste obtained by adding and mixing the solvent, and a metal circuit board having a predetermined pattern is placed and brought into contact with the metallized metal layer with a brazing material such as silver brazing interposed therebetween. Thereafter, this is heated to a temperature of about 900 ° C. in a reducing atmosphere to melt the brazing material paste and the brazing material. It is manufactured by joining through brazing materials such as.

[0005]

However, in this conventional ceramic circuit board, the metal circuit boards joined to the upper and lower surfaces of the ceramic board are filled with a brazing material filled in a through hole formed in the ceramic board. The through hole provided in the ceramic substrate is filled with a brazing filler metal by adding an organic solvent and a solvent to the silver brazing powder (alloy powder of silver and copper) in the through hole of the ceramic substrate. After adding and mixing the brazing material paste obtained by adding
This is done by heating to a temperature of 0 ° C., where
A large amount of air existing between the silver brazing powders was entrapped in the molten silver brazing material and became porous, and the conduction resistance was as high as 7 to 10 μΩ · cm in specific resistance. Therefore, in a conventional ceramic circuit board, when a large current exceeding 10 A flows through the metal circuit board and the brazing material in the through hole, the brazing material portion filled in the through hole generates resistance heat, and the heat is soldered onto the metal circuit board. It acts on an electronic component such as a semiconductor element which is bonded and fixed via an adhesive material such as the above, and has a drawback that the electronic component cannot be stably operated at a high temperature.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and has as its object to effectively prevent the generation of a large amount of heat due to resistance heating and to keep electronic components such as semiconductor elements connected to a metal circuit board at an appropriate temperature. It is another object of the present invention to provide a ceramic circuit board that can operate normally and stably.

[0007]

A ceramic circuit board according to the present invention has a metal circuit board made of copper or aluminum attached to both sides of a ceramic substrate having a through-hole so as to cover the through-hole. A ceramic circuit board in which metal pillars made of copper or aluminum are arranged, and the metal pillars connect metal circuit boards on both sides of the ceramic substrate, and a length is provided between an inner wall surface of the through hole and an outer wall surface of the metal pillar. Is provided with a space of 30 μm to 200 μm.

According to the ceramic circuit board of the present invention, the metal circuit boards attached to both sides of the ceramic substrate are substantially free from pores arranged in the through holes of the ceramic substrate and have a specific resistance of 3 μΩ · cm or less. Because of the electrical connection through the metal pillar made of copper or aluminum, even if a large current exceeding 10A flows through the metal circuit board and the metal pillar, resistance heating occurs in the metal pillar and a large amount of heat is generated. As a result, electronic components such as semiconductor elements bonded and fixed on the metal circuit board using an adhesive such as solder are always at an appropriate temperature, and can be operated normally and stably for a long period of time.

Further, according to the ceramic circuit board of the present invention, since a space having a length of 30 μm to 200 μm is provided between the inner wall surface of the through hole of the ceramic substrate and the outer wall surface of the metal pillar, heat is applied to the ceramic circuit board. Is applied, even if the outer wall surface of the metal column expands and spreads due to the difference in thermal expansion coefficient between the ceramic substrate and the metal column, the expansion is absorbed by the space and the outer wall surface of the metal column penetrates. No cracks or cracks are generated in the ceramic substrate by expanding the inner wall surface of the hole, and as a result, the ceramic circuit substrate can be used normally and stably for a long period of time.

[0010]

Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of a ceramic circuit board according to the present invention, wherein 1 is a ceramic board, 2 is a metallized metal layer, and 3 is a metal circuit board.

The ceramic substrate 1 has a square shape,
Through holes 4 penetrating in the thickness direction are partially formed,
A metal column 5 is inserted into the through hole 4.

The ceramic substrate 1 has metallized metal layers 2 attached to the upper and lower surfaces thereof, and a metal circuit board 3 is brazed to the metallized metal layers 2.

The ceramic substrate 1 is made of an electrically insulating material such as an aluminum oxide sintered body, a mullite sintered body, a silicon carbide sintered body, an aluminum nitride sintered body, and a silicon nitride sintered body. When it is made of an aluminum oxide-based sintered body, an appropriate organic binder, a plasticizer, and a solvent are added to raw material powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide to form a slurry, and the slurry is formed. A ceramic green sheet (green ceramic sheet) is formed by employing a conventionally known doctor blade method or calendar roll method, and then the ceramic green sheet is subjected to an appropriate punching process to form a hole serving as a through hole 4. By sintering at a high temperature (about 1600 ° C.) A raw material powder such as minium is mixed with a suitable organic solvent and a solvent to prepare the raw material powder, and the raw material powder is formed into a predetermined shape having a hole to be a through hole 4 by a press molding machine. It is made by firing the compact at a temperature of about 1600 ° C.

The ceramic substrate 1 functions as a support member for supporting the metal circuit board 3, and has metallized metal layers 2 formed on both upper and lower surfaces thereof in a predetermined pattern. A metal circuit board 3 having a predetermined pattern is brazed to the metallized metal layer 2 thus formed.

The metallized metal layer 2 functions as a base metal layer when the metal circuit board 3 is brazed to the ceramic substrate 1 and is made of a high melting point metal material such as tungsten, molybdenum, manganese, etc. A metal paste obtained by adding and mixing an organic binder, a plasticizer, and a solvent is printed and applied in a predetermined pattern in advance on both upper and lower surfaces of a ceramic green sheet (ceramic raw sheet) to be a ceramic substrate 1 by firing. By doing so, a predetermined pattern and a predetermined thickness are attached to both upper and lower surfaces of the ceramic substrate 1.

The metallized metal layer 2 is coated on its surface with a metal having good conductivity, such as nickel or gold, having good corrosion resistance and good wettability with a brazing material by a plating method.
When the metallized metal layer 2 is adhered to the metallized metal layer 2, the metallized metal layer 2 and the metal circuit board 3 can be extremely firmly brazed. Therefore, in order to effectively prevent the metallized metal layer 2 from being oxidized and corroded, and to firmly braze the metallized metal layer 2 and the metal circuit board 3, the surface of the metallized metal layer 2 must be made of a conductive material such as nickel or gold. Preferably, a metal having good corrosion resistance and good wettability with the brazing material is applied to a thickness of 1 μm to 20 μm.

A metal circuit board 3 is attached to a metallized metal layer 2 attached to both upper and lower surfaces of the ceramic substrate 1 via a brazing material so as to cover a through hole 4 provided in the ceramic substrate 1. I have.

The metal circuit board 3 is made of copper or aluminum, and is mounted on the metallized metal layer 2 formed on the upper and lower surfaces of the ceramic substrate 1 via a brazing material such as silver brazing or aluminum brazing. .

The metal circuit board 3 made of copper or aluminum can be formed, for example, by applying a conventionally known metal working method such as a rolling method or a punching method to an ingot of copper or aluminum. Saga 50
It is formed in a predetermined pattern shape at 0 μm.

When the metal circuit board 3 is made of copper, if the metal circuit board 3 is formed of oxygen-free copper, the surface of the copper is oxidized by oxygen existing in the copper during brazing. The wettability with the brazing material is improved without being performed, and the bonding to the metallized metal layer 2 via the brazing material is strengthened. Therefore, when the metal circuit board 3 is made of copper, it is preferable that the metal circuit board 3 is formed of oxygen-free copper.

Further, if the metal circuit board 3 is coated with a metal made of nickel or the like having good conductivity, good corrosion resistance and good wettability with the brazing material by a plating method, the metal circuit board 3 is provided with a metal circuit board. Oxidation and corrosion of the board 3 can be effectively prevented, and the electrical connection between the metal circuit board 3 and an external electric circuit and the connection of electronic components such as semiconductor elements to the metal circuit board 3 are firmly made. be able to. Therefore, it is preferable that a metal made of nickel or the like and having good conductivity, good corrosion resistance and good wettability with the brazing material is applied to the surface of the metal circuit board 3 by plating.

Further, when a plating layer made of nickel is applied to the surface of the metal circuit board 3, a nickel-phosphorus amorphous alloy containing phosphorus in an amount of 8 to 15% by weight may be used. Surface oxidation can be prevented well and the wettability with solder can be maintained for a long time. Therefore, when a plating layer made of nickel is applied to the surface of the metal circuit board 3, phosphorous is contained inside the metal circuit board 3 in an amount of 8 to 1%.
It is preferable to contain 5% by weight to form a nickel-phosphorus amorphous alloy.

Further, when a plating layer made of a nickel-phosphorus amorphous alloy is applied to the surface of the metal circuit board 3, if the content of phosphorus with respect to nickel is less than 8% by weight or more than 15% by weight, nickel is added. There is a danger that it becomes difficult to form an amorphous alloy of phosphorus and the solder cannot be firmly bonded to the plating layer. Therefore, when a plating layer made of a nickel-phosphorus amorphous alloy is applied to the surface of the metal circuit board 3, the content of phosphorus with respect to nickel is preferably set in the range of 8 to 15% by weight, and more preferably. The range is preferably 10 to 15% by weight.

The plating layer made of nickel, which is deposited on the surface of the metal circuit board 3, has a thickness of 1.5 μm.
If it is less than 3, the surface of the metal circuit board 3 cannot be completely covered with the plating layer made of nickel, and there is a risk that oxidation corrosion of the metal circuit board 3 cannot be effectively prevented. If it exceeds, the intrinsic stress existing inside the plating layer made of nickel becomes large, and the ceramic substrate 1 will be warped or cracked. In particular, when the thickness of the ceramic substrate 1 is as thin as 700 μm or less, warpage or cracking of the ceramic substrate 1 becomes remarkable. Therefore, it is preferable that the thickness of the nickel plating layer deposited on the surface of the metal circuit board 3 be in the range of 1.5 μm to 3 μm.

Further, the brazing of the metal circuit board 3 to the metallized metal layer 2 adhered to the ceramic substrate 1 is performed by placing the metal circuit board 3 on the metallized metal layer 2 with, for example, a silver brazing material. (Silver: 72% by weight, copper: 28% by weight), aluminum brazing material (aluminum: 88% by weight, silicon: 12% by weight), and the like. 30 to 100 g / cm
^{In a} vacuum or neutral or reducing atmosphere with a load of ² applied, heat treatment to a predetermined temperature (about 900 ° C for silver brazing material, about 600 ° C for aluminum brazing material) to melt the brazing material In this case, the metallized metal layer 2 and the metal circuit board 3 are joined by the molten brazing material.

The ceramic substrate 1 to which the metal circuit board 3 is brazed also has metal columns 5 disposed inside the through holes 4, and the metal columns 5 are brazed on the upper and lower surfaces of the ceramic substrate 1. It functions to electrically connect between the metal circuit boards 3.

The metal column 5 is made of highly conductive copper (1.72 μΩ · cm) or aluminum (2.65 μΩ · cm) having a very small specific resistance of 3 μΩ · cm or less. Since the specific resistance is small, that is, since the conduction resistance of the metal pillar 5 is small, even if a large current exceeding 10 A flows through the metal circuit board 3 and the metal pillar 5, a large amount of resistance heat is generated from the metal circuit board 3 and the metal pillar 5. No heat is generated, and as a result, electronic components such as semiconductor elements bonded and fixed on the metal circuit board 3 by using an adhesive such as solder always have an appropriate temperature and operate normally and stably for a long period of time. It becomes possible.

The metal column 5 is formed into a column shape by subjecting a copper or aluminum ingot (lumps) to a conventionally known metal processing method such as a rolling method, a punching method, or a drawing method. For example, a through-hole 4 provided in the ceramic substrate 1 is manufactured by attaching a brazing material such as a silver brazing material in the case of copper or an aluminum brazing material in the case of aluminum to the upper and lower end surfaces of the metal pillar.
Inside, it is arranged in a state where both end surfaces are joined to the metal circuit board 3 attached to the upper and lower surfaces of the ceramic substrate 1 via the brazing material.

When the metal column 5 is made of copper, if the metal column 5 is formed of oxygen-free copper, the surface of the copper is oxidized by the oxygen existing in the copper during brazing. The wettability with the brazing material is improved without being performed, and the bonding to the metal circuit board 3 via the brazing material is strengthened. Therefore, when the metal column 5 is made of copper, it is preferable to form the metal column 5 with oxygen-free copper.

When the diameter of the metal column 5 is less than 200 μm, the conduction resistance of the metal column 5 increases, and when a large current exceeding 10 A flows, a large amount of heat may be generated due to resistance heating. . Therefore, it is preferable that the diameter of the metal column 5 is 200 μm or more, preferably 350 μm or more. In particular, if the diameter of the metal column 5 is set to 350 μm or more, even if a large current exceeding 20 A flows through the metal column 5, a large amount of heat due to resistance heating is not generated, thereby bonding the solder or the like onto the metal circuit board 3. An electronic component such as a semiconductor element bonded and fixed using a material can always be kept at an appropriate temperature, and the electronic component can be operated normally and stably for a long period of time.

Further, in the present invention, the length between the inner wall surface of the through hole 4 of the ceramic substrate 1 and the outer wall surface of the metal pillar 5 is 3 mm.
It is important to provide a space of 0 μm to 200 μm.

The length between the inner wall surface of the through hole 4 of the ceramic substrate 1 and the outer wall surface of the metal column 5 is 30 μm to 200 μm.
If a space of m is provided, when heat is applied to the ceramic circuit board, even if the outer wall surface of the metal column 5 expands and spreads due to the difference in thermal expansion coefficient between the ceramic substrate 1 and the metal column 5, The expansion is absorbed in the space, and the outer wall surface of the metal column 5 does not spread the inner wall surface of the through hole 4 to cause cracks or cracks in the ceramic substrate 1. It can be used normally and stably.

When the length between the inner wall surface of the through hole 4 of the ceramic substrate 1 and the outer wall surface of the metal column 5 is less than 30 μm, when heat is applied to the ceramic circuit board, the ceramic substrate 1 and the metal column 5 When the outer wall surface of the metal column 5 expanded due to the difference in thermal expansion coefficient between the metal substrate 5 and the inner wall surface of the through-hole 4 of the ceramic substrate 1 expands, cracks and cracks occur in the ceramic substrate 1, and when it exceeds 200 μm, When the metal column 5 is inserted into the through hole 4 of the ceramic substrate 1, the metal column 5
When the metal circuit board 3 and the metal pillar 5 are inclined and fall down, it is difficult to securely and firmly join the metal circuit board 3 and the metal pillar 5, and a large current exceeding 10A flows. A large amount of heat is generated due to the resistance heat generation, which causes malfunction of electronic components such as semiconductor elements bonded and fixed on the metal circuit board 3. Therefore, the space between the inner wall surface of the through hole 4 of the ceramic substrate 1 and the outer wall surface of the metal column 5 is specified to have a length in the range of 30 μm to 200 μm.

Thus, according to the above-described ceramic circuit board, electronic components such as semiconductor elements are bonded and fixed to the metal circuit boards 3 attached to the upper and lower surfaces of the ceramic substrate 1 via an adhesive such as solder. If each electrode of an electronic component such as a device is electrically connected to the metal circuit board 3 via an electrical connection means such as a bonding wire, the electronic component such as a semiconductor device is mounted on the ceramic circuit board, and at the same time, the metal circuit board is mounted. If the electronic component 3 is electrically connected to an external electric circuit, electronic components such as semiconductor elements are connected to the external electric circuit.

Next, another embodiment of the present invention will be described with reference to FIG. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals.

In the ceramic circuit board of FIG. 2, a metal circuit board 3 of a predetermined pattern is attached to both upper and lower surfaces of the ceramic board 1 via an active metal brazing material 6, and at the same time, in the thickness direction provided on the ceramic board 1. Metal pillars 5 are arranged in through holes 4 penetrating by attaching both end surfaces to metal circuit board 3 via brazing material.

The metal pillars 5 arranged in the through holes 4 provided in the ceramic substrate 1 have both ends attached to the metal circuit board 3 via brazing materials, whereby the upper and lower surfaces of the ceramic substrate 1 Is electrically connected via the metal pillar 5.

The ceramic substrate 1 having the through holes 4
Is formed of an electrically insulating material such as an aluminum oxide sintered body, a mullite sintered body, a silicon nitride sintered body, an aluminum nitride sintered body, and a silicon carbide sintered body. In the case of a sintered body, raw materials such as silicon nitride, aluminum oxide, magnesium oxide, and yttrium oxide are mixed with an appropriate organic binder, a plasticizer, and a solvent to form a slurry, and the slurry is mixed with a conventionally known doctor. A ceramic green sheet (ceramic green sheet) is formed by employing a blade method or a calendar roll method, and then the ceramic green sheet is subjected to an appropriate punching process to form a predetermined shape, and a plurality of sheets are laminated as necessary. Then, it is formed into a molded body.
It is manufactured by firing at a high temperature of ° C.

Further, a metal circuit board 3 is attached via an active metal brazing material 6 so as to cover the through holes 4 formed in the ceramic substrate 1 on both upper and lower surfaces of the ceramic substrate 1.
The metal circuit board 3 is made of copper or aluminum. By applying a conventionally known metal working method such as a rolling method or a punching method to a copper or aluminum ingot, a predetermined pattern having a thickness of, for example, 500 μm is formed. Formed.

When the metal circuit board 3 is made of copper, it is formed of oxygen-free copper. When the oxygen-free copper is attached via the active metal brazing material 6, the surface of the copper is Active metal brazing material 6 without being oxidized by oxygen existing in copper
The wettability of the metal circuit board 3 with the ceramic substrate 1 via the active metal brazing material 6 becomes strong. Therefore, when the metal circuit board 3 is made of copper, it is preferable that the metal circuit board 3 is formed of oxygen-free copper.

The ceramic substrate 1 has metal pillars 5 disposed inside the through holes 4. The metal columns 5 electrically connect the metal circuit boards 3 on the upper and lower surfaces of the ceramic substrate 1, which are brazed. To act.

The metal column 5 is made of highly conductive copper (1.72 μΩ · cm) or aluminum (2.65 μΩ · cm) having a very small specific resistance of 3 μΩ · cm or less. Since the specific resistance is small, that is, since the conduction resistance of the metal pillar 5 is small, even if a large current exceeding 10 A flows through the metal circuit board 3 and the metal pillar 5, a large amount of resistance heat is generated from the metal circuit board 3 and the metal pillar 5. No heat is generated, and as a result, electronic components such as semiconductor elements bonded and fixed on the metal circuit board 3 by using an adhesive such as solder always have an appropriate temperature and operate normally and stably for a long period of time. It becomes possible.

The metal column 5 is formed into a column shape by subjecting a copper or aluminum ingot (lumps) to a conventionally known metal processing method such as a rolling method, a punching method, or a drawing method. For example, a through-hole 4 provided in the ceramic substrate 1 is manufactured by attaching a brazing material such as a silver brazing material in the case of copper or an aluminum brazing material in the case of aluminum to the upper and lower end surfaces of the metal pillar.
Inside, it is arranged in a state where both end surfaces are joined to the metal circuit board 3 attached to the upper and lower surfaces of the ceramic substrate 1 via the brazing material.

When the metal column 5 is made of copper, if the metal column 5 is formed of oxygen-free copper, the surface of the copper is oxidized by oxygen existing in the copper during brazing. The wettability with the brazing material is improved without being performed, and the bonding to the metal circuit board 3 via the brazing material is strengthened. Therefore, when the metal column 5 is made of copper, it is preferable to form the metal column 5 with oxygen-free copper.

When the diameter of the metal column 5 is less than 200 μm, the conduction resistance of the metal column 5 increases, and when a large current exceeding 10 A flows, a large amount of heat may be generated due to resistance heating. . Therefore, it is preferable that the diameter of the metal column 5 is 200 μm or more, preferably 350 μm or more. In particular, if the diameter of the metal column 5 is set to 350 μm or more, even if a large current exceeding 20 A flows through the metal column 5, a large amount of heat due to resistance heating is not generated, thereby bonding the solder or the like onto the metal circuit board 3. An electronic component such as a semiconductor element bonded and fixed using a material can always be kept at an appropriate temperature, and the electronic component can be operated normally and stably for a long period of time.

Further, the metal circuit board 3 is made of an active metal brazing material 6.
Is used, and the metallized metal layer is not required, so that the metallized metal layer is not required, and the upper and lower surfaces of the ceramic substrate 1 are brazed and attached. When the metal circuit board 3 is formed of copper, the active metal brazing material 6 is silver-copper. A eutectic alloy to which a metal such as titanium, zirconium or hafnium or a hydride thereof is added in an amount of 2 to 5% by weight, or when the metal circuit board 3 is formed of aluminum, an aluminum-silicon eutectic alloy is added to titanium. , Zirconium, hafnium or other metal or a hydride thereof is preferably added in an amount of 2 to 5% by weight.

Attachment of the metal circuit board 3 to the ceramic substrate 1 having the through holes 4 using the active metal brazing material 6 is performed, for example, when the metal circuit board 3 is made of copper, silver-copper is used. Alloys such as titanium, zirconium, hafnium or the like, or hydrides thereof added in an amount of 2 to 5% by weight.
An active metal brazing material paste is prepared by mixing an organic solvent and a solvent with addition of a metal such as titanium, zirconium, hafnium or a hydride thereof to a silicon eutectic alloy in an amount of 2 to 5% by weight, and then forming an active metal brazing paste. The active metal brazing material paste is printed and applied in a predetermined pattern on both upper and lower surfaces by employing a conventionally known screen printing method,
Next, the metal pillars 5 are inserted and arranged in the through holes 4 of the ceramic substrate 1 and the metal circuit board 3 is placed on the active metal brazing material paste printed and applied on both the upper and lower surfaces of the ceramic substrate 1. , At a predetermined temperature (about 900 ° C for copper,
Heat treatment is performed at about 600 ° C. for aluminum) to melt the active metal brazing material 6 and the brazing material adhered to both end surfaces of the metal pillars 5. The molten active metal brazing material 6 and the brazing material are used to form a ceramic substrate. 1 and the metal circuit board 3 and the metal circuit board 3 and the metal column 5 are joined.

In this ceramic circuit board, the specific resistance of the metal column 5 is as small as 3 μΩ · cm or less, that is, the conduction resistance of the metal column 5 is small, as in the above-described embodiment. Even if a large current exceeding 10 A flows, a large amount of heat is not generated from the metal circuit board 3 and the metal pillar 5 due to resistance heating, and as a result, the metal circuit board 3
Electronic components such as semiconductor elements, which are adhered and fixed using an adhesive such as solder, are always at an appropriate temperature, and can be operated normally and stably for a long period of time.

In the present invention, the length between the inner wall surface of the through hole 4 of the ceramic substrate 1 and the outer wall surface of the metal column 5 is 3 mm.
It is important to provide a space of 0 μm to 200 μm.

The length between the inner wall surface of the through hole 4 of the ceramic substrate 1 and the outer wall surface of the metal column 5 is 30 μm to 200 μm.
If a space of m is provided, when heat is applied to the ceramic circuit board, even if the outer wall surface of the metal column 5 expands and spreads due to the difference in thermal expansion coefficient between the ceramic substrate 1 and the metal column 5, The expansion is absorbed in the space, and the outer wall surface of the metal column 5 does not spread the inner wall surface of the through hole 4 to cause cracks or cracks in the ceramic substrate 1. It can be used normally and stably.

When the length between the inner wall surface of the through hole 4 of the ceramic substrate 1 and the outer wall surface of the metal column 5 is less than 30 μm, when heat is applied to the ceramic circuit board, the ceramic substrate 1 and the metal column 5 When the outer wall surface of the metal column 5 expanded due to the difference in thermal expansion coefficient between the metal substrate 5 and the inner wall surface of the through-hole 4 of the ceramic substrate 1 expands, cracks and cracks occur in the ceramic substrate 1, and when it exceeds 200 μm, When the metal column 5 is inserted into the through hole 4 of the ceramic substrate 1, the metal column 5
When the metal circuit board 3 and the metal pillar 5 are inclined and fall down, it is difficult to securely and firmly join the metal circuit board 3 and the metal pillar 5, and a large current exceeding 10A flows. A large amount of heat is generated due to the resistance heat generation, which causes malfunction of electronic components such as semiconductor elements bonded and fixed on the metal circuit board 3. Therefore, the space between the inner wall surface of the through hole 4 of the ceramic substrate 1 and the outer wall surface of the metal column 5 is specified to have a length in the range of 30 μm to 200 μm.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0053]

According to the ceramic circuit board of the present invention,
The metal circuit boards attached to both sides of the ceramic substrate are electrically connected to each other through metal columns made of copper or aluminum having a specific resistance of 3 μΩ · cm or less with few pores arranged in the through holes of the ceramic substrate. Therefore, even if a large current exceeding 10 A flows through the metal circuit board and the metal pillar, resistance heat is generated in the metal pillar and a large amount of heat is not generated. As a result, solder or the like is formed on the metal circuit board. Electronic components, such as semiconductor elements, which are bonded and fixed using the above-mentioned adhesive, are always at an appropriate temperature, and can be operated normally and stably for a long period of time.

According to the ceramic circuit board of the present invention, a space having a length of 30 μm to 200 μm is provided between the inner wall surface of the through-hole of the ceramic substrate and the outer wall surface of the metal pillar. Is applied, even if the outer wall surface of the metal column expands and spreads due to the difference in thermal expansion coefficient between the ceramic substrate and the metal column, the expansion is absorbed by the space and the outer wall surface of the metal column penetrates. No cracks or cracks are generated in the ceramic substrate by expanding the inner wall surface of the hole, and as a result, the ceramic circuit substrate can be used normally and stably for a long period of time.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a ceramic circuit board of the present invention.

FIG. 2 is a sectional view showing another embodiment of the ceramic circuit board of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ceramic substrate 2 ... Metallized metal layer 3 ... Metal circuit board 4 ... Through-hole 5 ... Metal column 6 ... Active metal brazing material

Claims (1)

[Claims] A metal circuit board made of copper or aluminum is attached to both sides of a ceramic substrate having a through hole so as to cover said through hole, and a metal column made of copper or aluminum is arranged in said through hole. A ceramic circuit board in which metal circuit boards on both sides of a ceramic substrate are connected by metal pillars, wherein a space having a length of 30 μm to 200 μm is provided between an inner wall surface of the through hole and an outer wall surface of the metal pillar. Characteristic ceramic circuit board.