JPH07135275A - Heat radiating substrate, its manufacture, and plastic package using it - Google Patents

Abstract

PURPOSE:To provide a heat radiating plate which can have a desired coefficient of thermal expansion, can be improved in heat conductivity and strength, and can be reduced in weight, the manufacturing method of the substrate, and a plastic package using the substrate. CONSTITUTION:A metallic composite material for a heat radiating substrate is composed of a base material having two surfaces, a front surface and rear surface, and a clad material which is tightly bonded to at least one surface of the base material. The base material contains aluminum and the clad material contains molybdenum. The ply material is a layer material provided at, at least, one surface of the base material. The composite material has a coefficient of thermal expansion of 9X10<-6>/ deg.C to 23X10<-6>/ deg.C as a whole. At the time of manufacturing the composite material, the base material containing at least aluminum and having two surfaces, front surface and rear surface, and the clad material composed of molybdenum are stuck to each other under a static pressure or under the combination of the static pressure and rolling at a room temperature or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal composite material for a heat dissipation board, and more particularly to a heat dissipation board composed of a base material made of aluminum or an aluminum alloy and a composite material containing molybdenum, and a plastic package having the heat dissipation board. .

[0002]

2. Description of the Related Art Recently, in addition to high density and high speed, a package that can be mass-produced at low cost has been studied. Therefore, what is called a plastic package using a plastic material rather than a so-called expensive ceramic has been proposed. The semiconductor chip mounted on the heat dissipation substrate of this type of plastic package is resin-molded. Enclosed in this plastic package. In order to promote the general-purpose use of chips, it is necessary to use a material that has a thermal expansion coefficient similar to that of the package material or that considers the thermal compatibility after package assembly, and the processing, plating, and brazing required for the package. Good quality is also required.

Further, as the size of the package increases with the high integration of the chips, the weight of the heat dissipation board provided for this also tends to be more strict in terms of package design.

[0004]

In order to meet the demand for reducing the weight of the heat dissipation substrate, the coefficient of thermal expansion of the heat dissipation substrate should be set to silicon (Si) or gallium arsenide (G) of the semiconductor element.
It must be larger than that of aAs). From such a background, copper (Cu) -tungsten (W) -based composite materials, Cu-molybdenum (Mo) -based composite materials, and the like have been proposed for semiconductor element mounting substrates. These composite materials are formed by impregnating a refractory metal, for example, a porous sintered body of tungsten with Cu. However, in these materials, the range of the coefficient of thermal expansion allowed for the heat dissipation substrate for plastic packages is still uncertain.

Therefore, a technical problem of the present invention is to dissipate a heat dissipation board having a coefficient of thermal expansion suitable for a plastic package,
It is to provide a manufacturing method thereof and a plastic package using the same.

[0006]

According to the present invention, the front and back sides 2
A metal composite material including a base material having a surface and a bonding material in close contact with at least one of the two surfaces of the base material, the base material including aluminum, and the bonding material including molybdenum; Is a layered material located on at least one surface of the base material, and the thermal expansion coefficient of the entire composite material is within the range of 9 to 23 × 10 ⁻⁶ / ° C. can get.

Further, according to the present invention, a base material having at least two sides including aluminum and a front surface and a back surface, and a composite material containing molybdenum are joined at room temperature or higher by static pressure or a combination of static pressure and rolling. A method of manufacturing a heat dissipation substrate for a plastic package, which is characterized in that

[0008]

Embodiments of the present invention will be described below with reference to the drawings. (Example 1) Ni (3 μm) plated by a zinc substitution method as a material for a base material has a diameter (D) of 200 mm and a thickness (T).
For 0.75mm Al plate and the material for the laminated material,
Mo plates having the same diameter and a thickness of 0.15 mm were laminated with Mo / Al (L) / Mo so as to have three layers and bonded by hot pressing. The bonding conditions at this time are that the load was 280 kgf / cm ² and the heating temperature was 500 ° C. for 2 hours in vacuum. The thickness of the laminated board thus completed is 1.05 mm, and the thickness of this is mesh # 8000.
The thickness was 1.0 mm by lapping both sides with abrasive grains.

The shape of each layer of this laminate was uniform as shown in FIG. 1, and no so-called constriction was observed.
The coefficient of thermal expansion is 12.4 × 10 ^-6 / ° C, and the thermal conductivity is 1
It was 98 W / mK. It was confirmed that the density was 4.8 g / cm ³ and the bonding strength was 2.0 kgf / mm ^2, which was sufficiently strong. Furthermore, this composite board was punched out to a size of □ 22 mm by the floating method, and N
When i-plated, no cracks were seen on the outer periphery,
A good heat dissipation substrate was obtained without unevenness or swelling of the plating.
Moreover, when the cross section was observed, the minimum amount of the laminated material (Mo) was 0.095 mm, and the minimum amount of the base material {Al (ell)} was 0.449 mm. The whole composite material after joining is
It was in the range of 0.99 to 1.01 mm. The thickness deviation is a percentage of the maximum value (Tmax) of the layer to be measured-the minimum value (Tmin) of the layer divided by the average value (Ta) of the layer thickness {= (Tmax- Tmin) × 100 / Ta
(%)}, And 3.1% for the laminated material and 2.4% for the base material. (Example 2) Al having a thickness of 2.65 mm as a base material
0.18 mm thick M for the (L) plate and the material for the laminated material
The o-plate was adhered according to the same procedure and conditions as in Example 1. The laminated plate had a thickness of 3.01 mm and was cold-rolled to a thickness of 3.0 mm. The deviation was 2.2% in the laminated material and 4.8% in the base material. Example 1
Similar to, the shape of each layer of this laminate was uniform and no constriction was observed. The coefficient of thermal expansion of this laminated material is 1
The weight was 7.4 × 10 ^-6 / ° C, the thermal conductivity was 215 W / mK, and the density was 3.6 g / cm ³ . Bonding strength is 4.
It was 9 kgf / mm ² , which was confirmed to be sufficiently strong, and the machinability and plating property were also good. (Example 3) An Al (ell) plate having a thickness of 1 mm and a Mo plate having a thickness of 15 μm were laminated on a material for a base material and a Mo material having a thickness of 15 μm in three layers and bonded by hot pressing. The bonding condition at this time is
This is because the load was kept at 200 kgf / cm ² and the heating temperature was 550 ° C. for 2 hours in vacuum. The thickness of the laminated plate after processing was 1.03 mm, and this was finished by lapping to a thickness of 1.0 mm. The layer shape of this laminate was uniform, and no constriction was observed at all, which was good. The thickness deviation was 3.3% for the laminated material and 0.5% for the base material. The coefficient of thermal expansion is 21.8 × 10 ^-6
/ ° C, thermal conductivity 230W / mK, bonding strength 3.2k
It showed gf / mm ² and was confirmed to have sufficient strength. Furthermore, the density was as light as 3.1 g / cm ^3, and the machinability and plating property were also good.

According to the experiments conducted by the present inventors, the material required for the heat dissipation substrate for a plastic package has a coefficient of thermal expansion of 9 to 23 × 10 ^-6 / ° C. The materials in Examples 1 to 3 all satisfied this requirement.

Further, in the above embodiment, as the pressure welding method, the base material and the composite material containing molybdenum are joined at room temperature or higher by static pressure or a combination of static pressure and rolling. By hot pressing or HIP, which is a pressure welding method using these dies, a desired plate thickness having a desired layer thickness ratio without nonuniform deformation can be obtained by setting conditions. In this way, Mo / Al (Mo) / Mo 3
Not only the layer structure material, but also the Mo / Al (ell) two-layer structure material can be easily manufactured, and each layer is finished uniformly. Furthermore, if necessary, if the surface is processed by rolling about a few percent,
It can be a material that is smooth and has good adhesion.

Further, in the above embodiment, by plating at least one surface of the base material and the bonding material, the soldering property and the brazing property are improved, and the adhesive strength between the base material and the bonding material is increased. You can

According to the experiments conducted by the present inventors, in order to obtain a material having a thermal expansion coefficient equivalent to that of the conventional 20 mass% Cu-Mo sintered composite material, the layer ratio Mo: Al ): Mo = 1: 1: 1, and the density at this time is 7.
It becomes 0 g / cm ³ . Further, in the case of 80 mass% Cu-Mo equivalent, the density becomes 4.1 g / cm ³ at the same ratio = 1: 8: 1, and the weight is reduced by 50% or more. Moreover, since the outer surface is made of Mo, scratches and dents are less likely to occur, and the plating process becomes easy.

In the present invention, the lower limit of the ratio of the thickness of the base material to the total thickness of the laminated material is 3: 1 (2: 1, 1: 1 etc. are not included). The reason is that the total thickness is 0.5 to 3 m.
m is preferable, because the value of the processing accuracy of each plate affects the finish, and if it is smaller than this, desired properties, adhesive strength, coefficient of thermal expansion of the entire composite material, thickness deviation, density, etc. This is because it is difficult to obtain. On the other hand, in the present invention, the upper limit is set to 70: 1 (71: 1, 72: 1, etc. are not included). When the upper limit is exceeded, market demand is small and it cannot be called a composite material. Is lost.

[0015]

As described above, according to the present invention, a desired heat expansion coefficient is obtained, high thermal conductivity and high strength are provided, and a metal composite material for a heat dissipation substrate, which can be reduced in weight, is provided. A manufacturing method can be provided.

[Brief description of drawings]

FIG. 1 is a metallurgical micrograph showing a metal structure of a heat dissipation substrate according to an example of the present invention.

Claims (7)

[Claims] 1. A metal comprising a base material having two front and back surfaces and a bonding material in close contact with at least one of the two surfaces of the base material, wherein the base material contains aluminum and the bonding material contains molybdenum. In the composite material, the composite material is a layered material located on at least one surface of the base material, and the thermal expansion coefficient of the entire composite material is 9 to 23 × 10 ^−6.
A heat dissipation board having a temperature range of / ° C. 2. The heat dissipation board according to claim 1, wherein the ratio of the thickness of the base material to the total thickness of the laminated material is 3: 1 to 1.
A heat dissipation board having a range of 70: 1. 3. The heat dissipation board according to claim 2, wherein at least one surface of the base material and the mating material is plated. 4. The heat dissipation board according to claim 1, wherein the adhesive strength of the base material and the laminated material due to the tension between the layers is at least 2 kgf / mm ^2. Heat dissipation board. 5. A plastic package comprising the heat dissipation board according to claim 4. 6. A base material having at least two sides of aluminum, which includes front and back surfaces, and a composite material containing molybdenum,
A method for manufacturing a heat dissipation board, which comprises bonding by static pressure or a combination of static pressure and rolling at room temperature or higher. 7. The method of manufacturing a heat dissipation board according to claim 6, wherein at least one surface of at least one of the base material and the bonding material is plated before bonding.