JP2005116767A - Heat dissipation member, circuit board, and semiconductor component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat dissipation member which has a double-layered structure by joining a ceramics member to both sides of a heatsink formed of a metal or the like, has high yield in manufacturing, and is excellent in heat-resistant cycle property. <P>SOLUTION: The heat dissipation member 1 is formed by joining ceramics members 1b, 1c to both sides of a heatsink 1a formed of a metal or the like. The surface roughness Ra of a junction surface in contact with other members of the ceramics members 1b, 1c is made ≤2.0 μm. Yield in manufacturing and heat-resistance cycle property can be remarkably improved simultaneously. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat radiating member on which a heat generating electronic component such as a semiconductor element is mounted, a circuit board, and a semiconductor component in which a semiconductor element is assembled.

  So-called exothermic electronic components such as power modules and switching power supply modules incorporated in IGBTs used for inverter control of electric vehicles, hybrid vehicles, and household devices literally generate heat when energized. Since this heat causes troubles such as hindering normal operation of semiconductor elements and causing cracks in the circuit board, usually these heat-generating electronic components are integrally provided with heat dissipation members such as copper plates and aluminum plates. It has been. In many cases, a heat sink is attached to the lower surface of the heat radiating member as a further heat countermeasure.

When a ceramic member is joined to both surfaces of a heat radiating plate made of metal or the like to form a multilayer structure, a high-performance heat radiating member without warping can be obtained.
The present invention has been made to further improve such a heat radiating member having a multilayer structure. Specifically, an object of the present invention is to provide a heat radiating member having a high yield at the time of manufacture and excellent heat cycle resistance.

As described in claim 1, the heat dissipation member is formed by bonding ceramic members to both surfaces of a heat dissipation plate made of metal or the like, and the surface roughness Ra of the bonding surface in contact with the other members of the ceramic member is 2. A heat dissipating member having a thickness of 0 μm or less is provided.
Further, as described in claim 2, the ceramic member has a fracture toughness of 5 MPam ^0.5 or more, a three-point bending strength of 500 MPa or more, and a thermal conductivity of 50 W / mK or more. provide.
Further, as described in claim 3, the ceramic member is mainly composed of silicon nitride, and the silicon nitride includes a IIa group element component. .
Further, as described in claim 4, the silicon nitride of the ceramic member is 80 to 99% by weight, and the component of group IIa element of the ceramic member is 0.3 to 8% by weight in terms of oxide. A heat dissipation member as described is provided.
In addition, as described in claim 5, a circuit metal layer is integrally bonded to an outer surface of one of the two ceramic members of the heat dissipation member according to any one of claims 1 to 4. A circuit board is provided.
According to a sixth aspect of the present invention, there is provided a semiconductor component in which a semiconductor element is provided on the heat dissipating member according to any one of the first to fourth aspects or the circuit board according to the fifth aspect.

  In the invention of claim 1, the surface roughness Ra in accordance with JIS B 0601 of the joining surface of the ceramic member, for example, contacting the heat radiating plate, is 2. By making it 0 μm or less, a dramatic improvement in the yield during manufacturing and the heat cycle performance can be achieved at the same time.

In addition, in the heat dissipation member, the three elements of fracture toughness, three-point bending strength, and thermal conductivity of the ceramic member are extremely important. By defining these values to the values described in claim 2, the yield during manufacture is high. A heat dissipating member having excellent heat cycle characteristics and sufficient heat dissipating characteristics can be obtained. Incidentally, when the fracture toughness is 5 MPam ^0.5 or more, the decrease in production yield due to brittleness to cracks due to impact is suppressed, and the decrease in heat cycleability due to insufficient resistance to cracks is suppressed. In addition, when the bending strength is 500 MPa or more, handling is easy, and it is difficult to break during manufacturing, thereby suppressing a decrease in yield and suppressing a decrease in heat cycleability due to insufficient resistance to thermal stress. Further, if the thermal conductivity is 50 W / mK or more, the heat dissipation characteristics are sufficient and the temperature rise is suppressed. In the present invention, fracture toughness can be measured by JIS R 1607, three-point bending strength can be measured by JIS R 1601, and thermal conductivity can be measured by JIS R 1611.

  Silicon nitride selected as a material in the invention of claim 3 is excellent in mechanical properties such as strength and toughness among ceramics that can be used as an insulating plate, and is optimal for a ceramic member. Group IIa element has the effect of maintaining high thermal conductivity of ceramic members, improving sinterability, and improving productivity, and the synergistic effect of these components increases the yield and heat cycle during the manufacture of heat dissipation members. Greatly contributes to the improvement of sex. And the oxide conversion amount of the component of the said silicon nitride and a IIa group element is the best to mix | blend in the ratio of the range described in Claim 4.

  The circuit board according to claim 5, wherein a circuit metal layer is integrally joined to the heat dissipation member having the above configuration, and the semiconductor component according to claim 6, wherein a semiconductor element is provided on the heat dissipation member or the circuit board having the above configuration. The above benefits can be enjoyed.

Embodiments of the present invention will be described below with reference to the drawings. 1 is an exploded perspective view of the heat radiating member, FIG. 2 is an exploded perspective view of the semiconductor component, FIG. 3 is a front view showing a use state, and FIG. 4 is a schematic front view showing a bending test.
As shown in the exploded perspective view of FIG. 1, the heat dissipating member 1 is formed by bonding ceramic members 1b and 1c to the upper and lower surfaces of the heat dissipating plate 1a.

  The radiator plate 1a may be any material as long as it has heat dissipation properties, but preferably Al or Al alloy obtained by adding one or more metals from Cu, Si, Mg, etc. to Al or Al, or Cu. Alternatively, a metal and ceramic composite such as Cu alloy obtained by adding one or more of Cu, Fe, Ag, Zr, Mo, W, or the like, Al-SiC, or the like is preferable. This is because these materials are excellent in heat dissipation and low in cost.

The ceramic members 1b and 1c are made of, for example, silicon nitride, aluminum nitride, aluminum oxide or the like, and preferably silicon nitride. More preferably, silicon nitride is added with a IIa group element and baked. In particular, 80 to 99% by weight of a silicon nitride component is added to an oxide equivalent of 0.3 to 8% by weight of a IIa group element. What added the component is the best. Incidentally, when the amount of silicon nitride is 80% by weight or more, a decrease in thermal conductivity is suppressed, and a sufficient ratio of the silicon nitride particle portion to the grain boundary layer portion is secured, thereby suppressing a decrease in bonding strength. In addition, when the amount of the IIa group element component is 0.3% by weight or more in terms of oxide, the decrease in sinterability is suppressed. Is suppressed.
The component of the group IIa element is composed of Mg, Ca, Sr, and Ba, and is one kind of a compound containing a group IIa element such as a single group IIa element or an oxide, nitride, or carbonitride of the group IIa element. Are used alone or in combination of two or more. Inclusion of these IIa group elements greatly contributes to maintaining a high level of thermal conductivity, improving sinterability, and improving productivity of the ceramic members 1b and 1c.

Therefore, the ceramic members 1b and 1c have a fracture toughness in accordance with JIS R 1607 of ⁵ MPam ^0.5 or more, a three-point bending strength in accordance with JIS R 1601 (distance between fulcrums x = 30 mm in FIG. 4) of 500 MPa or more, JIS The material and dimensions are determined so that the thermal conductivity conforming to R 1611 is 50 W / mK or more. For example, 0.3 to 8% by weight of a IIa group element in terms of oxide is added to 80 to 99% by weight of a silicon nitride component, and a IIIa group element component (for example, ytterbium oxide (Yb ₂ Ceramic members 1b and 1c manufactured by adding O ₃ )) to produce a ceramic material and processing the ceramic material to a plate thickness of 0.2 mm to 0.5 mm satisfy the above properties. Whether or not the above properties are satisfied is confirmed using a JIS-defined sample piece made of the same material as the ceramic members 1b and 1c.

  The heat radiating plate 1a and the ceramic members 1b and 1c are joined by, for example, a brazing method, a direct bonded copper method, or the like. Surface roughness Ra = 2.0 μm or less conforming to

FIG. 2 shows a circuit board 3 in which a circuit metal layer 3a is bonded to the outer surface of one of the heat radiating members 1 (for example, the upper side in FIG. 2). The material of the circuit metal layer 3a is preferably Al or Al alloy obtained by adding one or more metals from Cu, Si, Mg, etc. to Al, or Al, or Cu, Cu, Fe, Ag, Zr, Mo, W Cu alloy etc. which added the 1 type (s) or 2 or more types from these etc. are good. The circuit metal layer 3a is bonded to the ceramic member 1b by, for example, a brazing method, a direct bonded copper method, or the like. The ceramic member 1b of the present invention is a bonding surface with the circuit metal layer 3a in FIG. The top surface is also finished to a surface roughness Ra = 2.0 μm or less in accordance with JIS B 0601.
By installing the semiconductor elements 4a, 4a on the circuit metal layer 3a by soldering or the like, a semiconductor component 4 such as a power module or a switching power supply module can be formed.

  The semiconductor component 4 formed as described above is formed on the fixing jig 7 by providing fixing jigs 7 at the four corners of the heat dissipating member 1 with respect to the mounting portions such as the heat sink 5 as shown in FIG. The screw 6 is fixed to the through hole 7a.

Ceramic members 1b and 1c made of a ceramic material in the ratio of Table 1 are brazed to a Cu heat sink 1a having a length x width x thickness of 70 mm x 40 mm x 3 mm, and the heat radiation member 1 of Examples 1 to 13 is obtained. Manufactured and tested for yield after joining ceramic members and heat cycleability. In this example, MgO was used as the component of the group IIa element, and Yb ₂ O ₃ was used as the component of the group IIIa element. In the heat cycle resistance test, a thermal cycle of room temperature → −40 ° C. → room temperature → 125 ° C. → room temperature was repeated, and the cracks entering the joint surface or the peeling state of the joint portion were observed.
For comparison, the heat radiating members 1 of Comparative Examples 1 to 9 are manufactured by brazing ceramic members 1b and 1c made of the ceramic material in the ratio of Table 1 to the same heat radiating plate 1a as in Examples 1 to 13. Similarly to Examples 1 to 13, the yield after joining the ceramic members and the heat cycle resistance were tested. The results are shown in Table 1.

The heat radiating members 1 of Examples 1 to 4 and Comparative Examples 1 and 2 in Table 1 differ from each other only in the surface roughness of the ceramic surfaces of the ceramic members 1b and 1c. According to the data on the post-joining yield and heat cycle characteristics of Examples 1 to 4 and Comparative Examples 1 and 2, the surface roughness of the ceramic members 1b and 1c is apparent in the yield and heat cycle characteristics of the heat dissipating member 1. In particular, when the surface roughness Ra of the ceramic members 1b and 1c is 2.0 μm or less, satisfactory results are obtained in terms of both post-joining yield and heat cycle resistance. I was able to confirm.
In addition, by comparing Comparative Examples 3 to 6 and Examples 1 to 13, the fracture toughness, bending strength, and thermal conductivity of the ceramic members 1b and 1c are important for increasing the yield and heat cycle resistance of the heat radiating member 1. Thus, satisfactory results are obtained within the specified range of the present invention, and the comparison between Comparative Examples 7 to 9 and Examples 1 to 13 shows the relationship between silicon nitride and IIa group elements constituting the ceramic members 1b and 1c. It was confirmed that the compounding ratio of the components is important for improving the yield and heat cycle performance of the heat dissipating member 1, and that satisfactory results were obtained within the specified range of the present invention.

Of course, the present invention is not limited to this embodiment. For example, in this embodiment, the semiconductor component 4 is installed on the heat sink 5 using the fixing jig 7. However, through holes may be formed in, for example, four corners of the heat radiating member 1, and the through holes may be fixed by screws. .
In this embodiment, oxides are used as the IIa group element component and the IIIa group element component, but they may be simple substances or other compounds.
Furthermore, the ceramic members 1b and 1c may contain one or more IVa, Va, and VIa group elements for coloring or improving the characteristics as long as the characteristics are not impaired.

It is a disassembled perspective view of a heat radiating member. It is a disassembled perspective view of a semiconductor component. It is a front view which shows a use condition. It is a schematic front view which shows a bending test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Radiation member 1a ... Radiation plate (other members joined to ceramic member)
DESCRIPTION OF SYMBOLS 1b ... Ceramic member 1c ... Ceramic member 3 ... Circuit board 3a ... Circuit metal layer (Other member joined to a ceramic substrate)
4 ... Semiconductor component 4a ... Semiconductor element

Claims (6)

A heat radiating member formed by joining ceramic members on both sides of a heat radiating plate made of metal or the like,
A heat radiating member characterized in that a surface roughness Ra of a bonding surface in contact with another member of the ceramic member is 2.0 μm or less. 2. The heat dissipation member according to claim 1, wherein the ceramic member has a fracture toughness of 5 MPam ^0.5 or more, a three-point bending strength of 500 MPa or more, and a thermal conductivity of 50 W / mK or more.   The heat radiating member according to claim 1 or 2, wherein the ceramic member contains silicon nitride as a main component, and the silicon nitride contains a IIa group element component.   The heat radiating member according to claim 3, wherein silicon nitride of the ceramic member is 80 to 99% by weight, and a component of group IIa element is 0.3 to 8% by weight in terms of oxide.   A circuit board comprising a circuit metal layer integrally joined to an outer surface of any one of the two ceramic members of the heat dissipation member according to claim 1.   A semiconductor component comprising a heat dissipation member according to any one of claims 1 to 4 or a circuit board according to claim 5 provided with a semiconductor element.

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