JP5856801B2 - Electronic device mounting substrate and heat dissipation device - Google Patents

Description

  The present invention relates to an electronic element mounting substrate in which an aluminum circuit layer for mounting an electronic element is brazed on one surface of an insulating substrate, and an aluminum layer is brazed on the other surface, and the electronic element mounting substrate The present invention relates to a heat radiating device.

  As an electronic element mounting substrate, a substrate in which a metal circuit layer is bonded to one side of an insulating substrate is known. In such a substrate, the insulating substrate is not only excellent in electrical insulation, but also is made of ceramic having excellent heat conductivity and heat dissipation, and the metal circuit layer has high conductivity and can be joined to the insulating substrate. High-purity aluminum is used as a new metal, and these are brazed with an Al—Si alloy brazing material. In addition, a heat dissipation device may be manufactured by laminating a heat sink on the other surface of the insulating substrate (see Patent Document 1).

  Since the heat sink is required to be lightweight, maintain strength, formability, and corrosion resistance, a high-strength aluminum alloy such as an Al-Mn alloy is used to relieve stress generated between the insulating substrate and the heat sink. In order to do this, a heat sink is joined via an aluminum layer as a buffer layer. The heat dissipation device has an asymmetric shape in which a heat sink is bonded to both surfaces of the insulating substrate via an aluminum circuit layer and a buffer layer, and thermal strain resulting from the asymmetric shape is applied to the buffer layer in a cooling cycle so that the insulating substrate There is a background that the influence on cracking and peeling of the bonding interface is increased. For this reason, the buffer layer is made of high-purity aluminum which is soft and has a large stress relaxation force, and the insulating substrate and the buffer layer are brazed with an Al—Si alloy brazing material in the same manner as the bonding of the metal circuit layer.

JP 2004-153075 A

  FIG. 4 is an enlarged view schematically showing the vicinity of the bonding interface between the insulating substrate (11) and the buffer layer (100) after brazing. As shown in FIG. 4, the crystal grains (101) (102) (103) (104) constituting the surface of the buffer layer (100) are not necessarily arranged at the same height, but arranged at irregular heights. In addition, a step is generated between adjacent crystal grains, and a gap is generated between the insulating substrate (11). It has been found that as the crystal grains become larger, the gap not only increases in dimension in the direction parallel to the surface of the insulating substrate (11), but also increases in the step (dimension in the material stacking direction). As described above, the material of the buffer layer (100) to be brazed to the insulating substrate (11) is high-purity aluminum, and the high-purity aluminum tends to coarsen the recrystallized grains. The level difference between the two is also large. In other words, the large crystal grain size increases the volume due to the step as compared with the fine crystal grain size. Therefore, when the buffer layer (100) is brazed to the insulating substrate (11), the brazing material is attached to the crystal grains (101) (103) that have retreated from the surface of the insulating substrate (11) toward the buffer layer (100). Accumulation (105) occurs and surplus brazing material remains at the joint interface.

  Further, the Al—Si based brazing filler metal is harder than the high-purity aluminum constituting the buffer layer, and if a brazing filler metal pool is generated at the joining interface, stress may be easily concentrated in the thermal cycle. In addition, as long as the heat dissipation device has an asymmetric shape on both sides of the insulating substrate, a measure for preventing the occurrence of thermal strain due to the asymmetric shape is required. For this reason, in order to improve the thermal durability of the electronic element mounting substrate, it is preferable that no surplus brazing material remains at the bonding interface or that the surplus brazing material amount remaining is small.

  In view of the background art described above, the present invention is an electronic device mounting substrate in which an aluminum circuit layer and an aluminum layer are brazed on both surfaces of an insulating substrate, and surplus brazing material remains at the bonding interface between the insulating substrate and the aluminum layer. It is an object of the present invention to provide an electronic element mounting substrate that can reduce thermal distortion caused by an asymmetric shape and a heat dissipation device using the electronic element mounting substrate.

  That is, the present invention has the configurations described in [1] to [9] below.

[1] An electronic element mounting substrate in which an aluminum circuit layer for mounting an electronic element is brazed on one surface of an insulating substrate, and an aluminum layer is brazed on the other surface,
At least the layer on the insulating substrate side of the aluminum layer is made of aluminum or an aluminum alloy having an average grain size of 10 to 500 μm after brazing and a tensile strength of 130 N / mm ² or less. A substrate for mounting an electronic device, characterized by comprising:

[2] The aluminum layer is made of a solid material made of aluminum or an aluminum alloy having an average grain size of 10 to 500 μm after brazing and a tensile strength of 130 N / mm ² or less. 2. The electronic element mounting substrate according to item 1 above.

[3] The aluminum layer is aluminum or aluminum in which the average grain size of the crystal grains after brazing is 10 to 500 μm and the tensile strength is 130 N / mm ² or less on the surface of the base material on the insulating substrate side 2. The electronic element mounting substrate according to item 1, wherein the electronic element mounting substrate is formed of a laminated material in which fine crystal layers made of an alloy are laminated.

  [4] The electronic element mounting substrate as described in [3] above, wherein the thickness of the fine crystal layer is 50 to 600 μm.

[5] The electronic element mounting substrate according to any one of [1] to [4], wherein the aluminum constituting the layer on the insulating substrate side of the aluminum layer is aluminum having an aluminum purity of 97.5 to 99.9% by mass. [6] The electronic element mounting according to any one of [1] to [4], wherein the aluminum alloy constituting the layer on the insulating substrate side of the aluminum layer is an aluminum alloy containing at least 0.01 to 0.8% by mass of Fe. Substrate.

[7] electronic device mounting board according to any one of aluminum or an aluminum alloy constituting the layer of the insulating substrate side of the aluminum layer is set forth in the preceding paragraph 1-6 having an average particle diameter of the metal compound has been made with 3μm or less.

[8] A method for producing an aluminum layer material for use in the electronic element mounting substrate according to any one of 1 to 7,
An aluminum layer material characterized by performing an intermediate annealing for 1 to 8 hours at 330 to 450 ° C. during rolling of a plurality of passes on the material lump, and a reduction rate of finish rolling to 15 to 40%. Manufacturing method.

  [9] A heat radiating device, wherein an aluminum layer of the insulating substrate of the electronic element mounting substrate according to any one of 1 to 7 is used as a buffer layer, and a heat sink is bonded onto the buffer layer.

In the electronic element mounting substrate described in [1] above, an aluminum circuit layer is brazed to one surface of the insulating substrate, and at least the layer on the insulating substrate side of the aluminum layer brazed to the other surface has crystal grains. The average particle size of the steel is refined to 10 to 500 μm, and the tensile strength is 130 N / mm ² or less.

Since the aluminum layer has a small level difference between adjacent crystal grains on the surface due to refinement of crystal grains, a brazing material reservoir generated at a bonding interface with the insulating substrate is also reduced. Alternatively, no brazing material accumulation occurs. Further, since the crystal grain interface area ratio is increased by the refinement of crystal grains, the brazing material diffuses into the crystal grain boundary and the brazing material remaining at the joint interface decreases. As a result, the amount of surplus brazing material remaining at the bonding interface is suppressed, or surplus brazing material does not remain. Further, by reducing the excess brazing material remaining as a brazing material pool at the joint interface, stress concentration in the brazing material pool in the cooling and heating cycle is prevented, and sufficient stress is obtained because the tensile strength is 130 N / mm ² or less. Since relaxation force can be obtained and thermal strain caused by the asymmetrical shape can be reduced, the thermal durability of the electronic element mounting substrate can be improved.

  According to the electronic element mounting substrate described in [2] above, the effect of improving the cooling durability can be obtained by the aluminum layer made of a solid material in which the average grain size and tensile strength of the crystal grains are defined.

  According to the electronic device mounting substrate described in [3] above, the aluminum is made of a laminate in which a fine crystal layer in which the average grain size and tensile strength of crystal grains are defined is laminated on the surface of the base material on the insulating substrate side. The effect of improving the cold durability can be obtained by the layer.

  According to the electronic element mounting substrate described in [4] above, since the thickness of the fine crystal layer of the laminated material is set to 50 to 600 μm, the effect of reducing excess brazing filler metal at the bonding interface and to the grain boundary By sufficiently obtaining the brazing filler metal diffusion effect, the above-mentioned effect of improving the cooling durability can be obtained.

According to the electronic device mounting substrate described in [5] and [6] above, by using a material having a defined composition, the average grain size of the crystal grains after brazing is 10 to 500 μm, and 130 N / An aluminum layer having a tensile strength of mm ² or less can be formed.

  According to the electronic device mounting substrate described in [7] above, since the average grain size of the intermetallic compound in the aluminum circuit layer is 3 μm or less, the average grain size of the crystal grains is controlled to 10 to 500 μm. Is easy.

According to the method for producing a material for an aluminum layer described in [8] above, the average grain size after brazing is obtained by performing intermediate annealing under the prescribed conditions and performing finish rolling at the prescribed reduction rate. A material having a diameter of 10 to 500 μm and a tensile strength of 130 N / mm ² or less can be produced.

According to the heat dissipation device described in [9] above, at least the insulating substrate side layer of the buffer layer of the electronic element mounting substrate has crystal grains refined and the tensile strength is regulated. For this reason, the amount of surplus brazing material remaining at the bonding interface between the insulating substrate and the buffer layer is suppressed, or surplus brazing material does not remain. Further, by reducing the excess brazing material remaining as a brazing material pool at the joint interface, stress concentration in the brazing material pool in the cooling and heating cycle is prevented, and sufficient stress is obtained because the tensile strength is 130 N / mm ² or less. Since it is possible to reduce the thermal strain caused by the asymmetric shape by obtaining a relaxation force, it is possible to improve the cooling durability of the heat dissipation device.

It is a longitudinal cross-sectional view which shows the temporary assembly of the electronic device mounting substrate concerning this invention, and the thermal radiation apparatus using this electronic device mounting substrate. FIG. 3 is a cross-sectional view showing a bonding interface between an insulating substrate after brazing and an aluminum layer (buffer layer) and the vicinity thereof in the electronic element mounting substrate according to the present invention. It is principal part sectional drawing which shows other embodiment of the aluminum layer in the board | substrate for electronic element mounting. In the conventional electronic device mounting board | substrate, it is sectional drawing which shows the joining interface of the insulated substrate after brazing, and an aluminum layer (buffer layer), and its vicinity.

  FIG. 1 shows an embodiment of an electronic element mounting substrate according to the present invention and a temporary assembly of a heat dissipation device manufactured using the electronic element mounting substrate in a cross section cut in a direction in which constituent members are stacked. .

  The electronic element mounting substrate (1) is composed of an insulating substrate (11) and an aluminum circuit layer (12) for mounting the electronic element that is superimposed on one surface of the insulating substrate (11). In the temporary assembly shown in FIG. 1, a brazing material foil (14) for bonding them is disposed between the insulating substrate (11) and the aluminum circuit layer (12). The temporary assembly of the heat dissipation device (2) is a tube type having a plurality of hollow portions on the other surface of the insulating substrate (11) of the electronic element mounting substrate (1) via a buffer layer (13). It is a superposition of heat sink (16), brazing material foil between the insulating substrate (11) and the buffer layer (13), and between the buffer layer (13) and the heat sink (16) (15) (17) is arranged. The buffer layer (13) is a layer brazed to the opposite surface of the aluminum circuit layer (12) to the insulating substrate (11), and corresponds to the aluminum layer in the present invention.

  In the heat dissipating device (2), the temporary assembly is collectively heated by brazing, and then the electronic element (18) is soldered onto the aluminum circuit layer (12). In the heat dissipation device (2) after brazing, the insulating substrate (11) to which the aluminum circuit layer (12) is brazed and the heat sink (16) are thermally coupled via the buffer layer (13) to form an electronic device. The heat generated by (18) is exhausted to the heat sink (16).

  In the present invention, the aluminum layer (buffer layer) of the electronic element mounting substrate is made of aluminum or an aluminum alloy in which at least the layer on the insulating substrate side has an average crystal grain size and tensile strength defined. The buffer layer (13) shown in FIG. 1 is a solid material made of the aluminum or aluminum alloy, and the buffer layer (20) shown in FIG. 3 is formed on the surface of the base material (21) on the insulating substrate (11) side. A laminated material in which fine crystal layers (22) made of aluminum or an aluminum alloy are laminated, all satisfying the conditions of the present invention.

  First, the buffer layer (13) made of a solid material will be described in detail.

  The buffer layer (13) has an average grain size of 10 to 500 μm after brazing and has a crystal structure finer than that of high-purity aluminum.

  FIG. 2 is an enlarged cross-sectional view schematically showing the bonding interface between the insulating substrate (11) and the buffer layer (13) after brazing and the vicinity thereof. As shown in FIG. 2, even if the crystal grains (31) (32) (33) (34) (35) (36) constituting the surface of the buffer layer (13) are not necessarily arranged at the same height, Since the crystal grains are miniaturized, the level difference between adjacent crystal grains (dimensions in the material stacking direction) is also reduced, and the crystal has retreated from the surface of the insulating substrate (11) to the buffer layer (13) side. The brazing material reservoir (37) generated in the parts of the grains (32) and (34) is also reduced. Or a level | step difference is lose | eliminated and a brazing material pool will not generate | occur | produce.

  The reason why the level difference between adjacent crystal grains becomes smaller as the crystal grains become smaller is as follows.

  Crystal grains having different crystal orientations have different linear expansion coefficients depending on directions. For this reason, when crystal grains having different crystal orientations are adjacent to each other, these crystal grains receive mutual rotational force or deformation force due to the difference in linear expansion coefficient during brazing. Furthermore, the load and frictional force applied to the material being brazed act as a force for rotating or deforming the crystal grains. And even if the rotation angle of the crystal grains is the same, the deviation becomes larger as the crystal grains become larger, and the deviation becomes smaller as the crystal grains become smaller. Even when receiving a deformation force, the displacement at the grain boundary increases by receiving the deformation force at a large crystal grain, and the displacement decreases at the grain boundary of a small crystal grain. Since a step between adjacent crystal grains is caused by such a shift, the step becomes smaller as the crystal grain becomes smaller.

  Therefore, when the crystal grains become small, the amount of surplus brazing material remaining at the bonding interface is suppressed, or the surplus brazing material does not remain and the amount of brazing material used is suppressed. In addition, since the crystal grain interface area ratio increases because the crystal grains are fine, the amount of surplus brazing filler metal remaining at the bonding interface with the insulating substrate (11) decreases even when the amount of brazing filler metal diffused into the crystal grain boundary increases. .

  In addition, it is preferable to reduce the excess brazing filler metal remaining as a brazing material reservoir at the bonding interface between the insulating substrate (11) and the buffer layer (13) in order to prevent stress concentration in the brazing filler metal reservoir in the thermal cycle. In addition, the thermal durability of the electronic element mounting substrate (1) can be improved.

  In the buffer layer (13) after brazing, if the average grain size exceeds 500 μm, the above effect is small, and if the average grain size is less than 10 μm, erosion by the brazing material increases during brazing and the bonding property may be reduced. There is. Therefore, the average particle diameter of the crystal grains after brazing of the buffer layer (13) in the present invention is 10 to 500 μm. The average grain size of preferred crystal grains is 40 to 450 μm. Since the average grain size of the crystal grains is the average grain size achieved after brazing, that is, by being subjected to brazing addition heat, the average grain size is not necessarily within the above range in the buffer layer (13) before brazing. Not always. Although this invention does not limit brazing conditions, the heating for 5 to 30 minutes at 590-620 degreeC can be recommended as brazing conditions.

The buffer layer (13) has a tensile strength of 130 N / mm ² or less as well as an average grain size of crystal grains. By defining the tensile strength at 130 N / mm ² or less, a sufficient stress relaxation force can be obtained and the thermal strain caused by the asymmetric shape can be reduced. Since a material having a low tensile strength provides a higher stress relaxation force, the present invention does not define the lower limit value of the tensile strength, but a material satisfying the condition that the average grain size of crystal grains is 10 to 500 μm In many cases, it has a tensile strength of 45 N / mm ² or more, and a tensile strength of 45 N / mm ² or more can be recommended from the viewpoint of ease of material selection. A preferred tensile strength is 45 to 120 N / mm ² , and a particularly preferred tensile strength is 50 to 110 N / mm ² .

As described above, by reducing the excess brazing material remaining as a brazing material reservoir at the bonding interface between the insulating substrate (11) and the buffer layer (13), stress concentration in the brazing material reservoir in the cold cycle is prevented, and the buffer layer (13 ) Is set to 130 N / mm ² or less, a sufficient stress relaxation force can be obtained to reduce the thermal strain caused by the asymmetric shape. The cooling durability of the device (2) can be improved.

  As factors controlling the average grain size and tensile strength of the crystal grains in the buffer layer (13), the chemical composition of the material constituting the buffer layer (13), the grain size of the intermetallic compound in the material, the production conditions of the material Can be mentioned.

As one of the materials constituting the buffer layer (13), aluminum having an aluminum purity of 97.5 to 99.9% by mass can be recommended. If the aluminum purity exceeds 99.9% by mass, the crystal grains may be coarsened. If the aluminum purity is less than 97.5% by mass, the tensile strength increases and a tensile strength of 130 N / mm ² or less is obtained. It becomes difficult to realize. A particularly preferable aluminum purity is 97.5 to 99% by mass. As another material constituting the buffer layer (13), an aluminum alloy containing 0.01 to 0.8% by mass of Fe having an effect of refining crystal grains can be recommended. When the Fe concentration is less than 0.01% by mass, the crystal grain refining effect is small. On the other hand, if 0.8% by mass is added, a sufficient crystal grain refining effect is obtained, so the addition of Fe exceeding 0.8% by mass is uneconomical. A particularly preferable Fe concentration is 0.1 to 0.6% by mass. The balance of the aluminum alloy is Al and inevitable impurities, but if it contains at least 0.01 to 0.8% by mass of Fe, a grain refinement effect can be obtained, so the aluminum purity is 97.5% by mass. If it is above, it is permitted to contain impurity elements other than Fe.

  In the aluminum or aluminum alloy constituting the buffer layer (13), the average particle size of the intermetallic compound is preferably 3 μm or less. If the average grain size of the intermetallic compound exceeds 3 μm, it tends to be difficult to control the crystal grains to a predetermined size, and a large intermetallic compound is formed between the insulating substrate (11) and the buffer layer (13). A state in which a large amount exists at the bonding interface is not preferable in maintaining the bonding reliability by brazing. For this reason, the average particle diameter of the intermetallic compound is preferably 3 μm or less from the viewpoint of ease of crystal grain control and bonding reliability. A particularly preferable average particle size of the intermetallic compound is 1 μm or less.

  The above-mentioned aluminum and aluminum alloy have high conductivity and thermal conductivity, and have good brazing properties with the insulating substrate (11). Therefore, the conditions for the material to be brazed to the insulating substrate (11) Meet.

  Moreover, although the buffer layer (13) shown in FIG. 1 is a punching metal having a plurality of circular through holes as a stress absorption space, the presence or absence and shape of the stress absorption space in the buffer layer can be arbitrarily set in the present invention. it can.

The buffer layer (13) has a thin plate shape, and is produced, for example, by performing a plurality of passes of hot rolling, cold rolling, and finish rolling on the material lump. In order to refine the average grain size of the crystal grains in the range of 10 to 500 μm, develop a tensile strength of 130 N / mm ² or less, and control the average grain size of the intermetallic compound to 1 μm or less, It is effective to define the intermediate annealing conditions and the rolling reduction of finish rolling. The intermediate annealing is preferably held at 330 to 450 ° C. for 1 to 8 hours. Annealing at less than 330 ° C. or less than 1 hour may excessively refine crystal grains, and annealing at more than 450 ° C. or more than 8 hours is uneconomical in terms of energy costs. Particularly preferable conditions for the intermediate annealing are 350 to 420 ° C. and 2 to 6 hours. Moreover, the time for performing the intermediate annealing under the above conditions is preferably after hot rolling or before finish rolling. The rolling reduction of finish rolling is preferably 15 to 40%. If the rolling reduction is less than 15%, recrystallization does not occur, and erosion may increase during brazing, and if the rolling reduction exceeds 40%, the crystal grains may become excessively small. A particularly preferred rolling reduction is 15 to 30%. The finish rolling may be performed by either a single pass or a plurality of passes, and the reduction rate when the finish rolling is performed by a plurality of passes is the total reduction rate.

  Since thermal strain due to excess brazing filler metal and asymmetric shape is a problem that occurs at the bonding interface between the insulating substrate and the buffer layer, at least the crystal grain size and tensile strength in the layer on the insulating substrate side are within the above-mentioned range. If it is made of the formed material, these problems occurring at the bonding interface can be solved. Therefore, in addition to the solid material (13) in FIG. 1, the laminated material (20) shown in FIG. 3 can be used as the buffer layer.

The buffer layer (20) shown in FIG. 3 is a laminated material in which the fine crystal layer (22) is laminated on the surface of the base material (21) on the side of the insulating substrate (11). Similar to the buffer layer (13) made of solid material, it is made of aluminum or an aluminum alloy having an average grain size of 10 to 500 μm after brazing and a tensile strength of 130 N / mm ² or less. Yes. Such a laminated material may be a clad rolled material or a brazed laminated material obtained by brazing two layers.

  In the buffer layer (20), the material of the base material (21) is preferably formed of a material softer than the fine crystal layer (22) and having a large stress relaxation force, and the aluminum purity is 99.99% by mass or more. High purity aluminum can be recommended. Further, the thickness (t) of the fine crystal layer (22) is preferably 50 μm or more in order to obtain the effect of reducing the excess brazing material at the bonding interface and the effect of diffusion of the brazing material to the grain boundaries. Further, if the thickness (t) is 600 μm, a sufficient effect can be obtained, and it is uneconomical to make it thicker. A particularly preferable thickness (t) of the fine crystal layer (22) is 150 to 400 μm. The thickness of the base material (21) is not limited and may be set as appropriate.

  When the buffer layer (20) is a clad rolled material, the buffer layer (20) is produced by rolling a plurality of passes by superposing the base material and the fine crystal layer material in accordance with a known clad rolled material manufacturing method. In this step, as in the production process of the solid material, intermediate annealing is performed at 330 to 450 ° C. for 1 to 8 hours, and finish rolling is performed at a rolling reduction of 15 to 40%, whereby crystal grains of the fine crystal layer (22) The average particle size, the tensile strength, and the average particle size of the intermetallic compound can be controlled within the ranges defined by the present invention.

  Further, when the buffer layer (20) is a brazed laminated material, brazing is performed by sandwiching a brazing material foil between the base material (21) processed into a predetermined thickness and the fine crystal layer (22). A brazing sheet in which a brazing material layer is clad with the fine crystal layer (22) as a core material is prepared, and this brazing sheet is brazed to the base material (21). In the former case, in the step of producing a fine crystal layer, in the latter case, in the step of producing a brazing sheet, the intermediate annealing is performed at 330 to 450 ° C. for 1 to 8 hours in the same manner as in the production process of the solid material. By carrying out finish rolling at a rolling reduction of ˜40%, the average grain size, tensile strength, and average grain size of the intermetallic compound in the fine crystal layer (22) are controlled within the ranges specified by the present invention. Can do. The brazing material is a brazing material such as an Al-Si alloy or an Al-Si-Mg alloy. The brazing of the brazed laminated material described above can be brazed together with other members when the electronic element mounting substrate (1) or the heat dissipation device (2) shown in FIG. 1 is temporarily assembled.

  Preferred materials for the other members constituting the electronic element mounting substrate (1) and the heat dissipation device (2) are as follows.

  Examples of the material constituting the insulating substrate (11) include ceramics such as aluminum nitride, aluminum oxide, silicon nitride, zirconium oxide, and silicon carbide. These ceramics are recommended not only because of their excellent electrical insulation, but also because they have good thermal conductivity and excellent heat dissipation.

  The aluminum circuit layer (12) preferably uses aluminum that has high conductivity and can relieve stress generated at the bonding interface with the insulating substrate (11), and is equivalent to the buffer layer (13). Alternatively, it is preferable to use high purity aluminum.

  The metal constituting the heat sink (16) is preferably a material excellent in lightness, strength maintenance, formability, and corrosion resistance, and an aluminum alloy such as an Al—Mn alloy can be recommended as having these characteristics. If the heat sink (16) has a flat outer surface on the buffer layer (13) side, it can be brazed to a large area with the buffer layer (13) to obtain high heat dissipation performance. There is no limitation on the shape or internal shape. Other shapes of the heat sink include a flat plate, a heat sink in which fins are brazed to the other surface of the flat plate, a heat sink in which fins are erected on the other surface of the flat plate, a tube heat sink in which fins are provided in the hollow portion, and the like.

  The material of the brazing foil (14), (15) and (17) is not limited, but for joining the materials of the aluminum circuit layer (12), insulating substrate (11), buffer layer (13) and heat sink (16) described above. As a suitable brazing material, an Al—Si based alloy and an Al—Si—Mg based alloy can be recommended.

  A heat dissipating device (2) including an electronic element mounting substrate (1) having a laminated structure referred to in FIG. 1 was produced by changing the materials of the buffer layer and the aluminum circuit layer. The members laminated in the heat dissipation device (2) are, in the order of lamination, an aluminum circuit layer (12), a brazing material foil (14), an insulating substrate (11), a brazing material foil (15), and a buffer layer (13) (20). , Brazing foil (17) and heat sink (16). Details of the members used are as follows.

[Buffer layer]
The buffer layers (13) of Examples 1 and 2 and Comparative Examples 1 and 2 are made of the solid material referred to in FIG. 1, each containing Fe at the concentration shown in Table 1, and the balance consisting of Al and inevitable impurities. An aluminum alloy was used. As a material for the buffer layer (13), hot rolling, cold rolling, and finish rolling were performed on the material lump to produce a thin plate having a thickness of 1.6 mm. In the process of producing these thin plates, intermediate annealing was performed at 420 ° C. for 4 hours when the plate thickness was 2.13 mm before finish rolling, and finish rolling was performed at a reduction rate of 25%.

  The produced thin plate for the buffer layer (13) was cut into 28 mm × 28 mm, and further cut to form 12 circular through holes with a diameter of 2 mm, which were used for temporary assembly of the heat dissipation device (2). .

  The buffer layer (20) of Example 3 is composed of a thin plate of the laminated material referred to in FIG. 3, and high purity aluminum having an Al purity of 99.99% by mass is used as the material of the base material (21). As the material of (22), an aluminum alloy containing Fe described in Table 1 and the balance consisting of Al and inevitable impurities was used. The laminated material is a rolled clad material, and the base material and the fine crystal layer are adjusted so that the thickness of the base material (21) is finally 1.3 mm and the fine crystal layer (22) is 300 μm. The materials were stacked and rolled by a plurality of passes to produce a rolled clad material having a thickness of 1.6 mm. In the step of producing the clad rolled material, intermediate annealing was performed at 420 ° C. for 4 hours when the plate thickness was 2.13 mm before finish rolling, and finish rolling was performed at a rolling reduction of 25%.

  The produced rolled clad material for the buffer layer (20) was cut into 28 mm × 28 mm, and further cut to form 12 circular through holes with a diameter of 2 mm to form a temporary assembly of the heat dissipation device (2). used.

[Aluminum circuit layer]
As the material of the aluminum circuit layer (12), Examples 1 and 2 and Comparative Examples 1 and 2 use an aluminum alloy having the same composition as each buffer layer (13), and Example 3 uses fine crystals of the buffer layer (20). An aluminum alloy having the same composition as the layer (22) was used.

  As a material for the aluminum circuit layer (12), hot rolling, cold rolling, and finish rolling were performed on the material lump to produce a thin plate having a thickness of 0.6 mm. In the process of producing these thin plates, as in the buffer layer material, intermediate annealing at 420 ° C. × 4 hours was performed, and finish rolling was performed at a reduction rate of 25%.

  The prepared thin plate for the aluminum circuit layer (12) was cut into 28 mm × 28 mm and used for the temporary assembly of the heat dissipation device (2).

[Other parts]
The members other than the buffer layers (13) and (20) and the aluminum circuit layer (12) were the same in each example.

  The insulating substrate (11) is a flat plate made of aluminum nitride and having a size of 30 mm × 30 mm × thickness 0.6 mm. The heat sink (16) is a flat multi-hole tube made of an Al-1 mass% Mn alloy. The brazing material foils (14), (15), and (17) are 30 μm thick Al-10 mass% Si-1 mass% Mg alloy foil.

[Brazing]
The temporary assemblies of Examples 1 to 3 and Comparative Examples 1 and 2 were vacuum brazed in a vacuum of 7 × 10 ⁻⁴ Pa at 600 ° C. for 20 minutes.

[Evaluation]
For the brazed heat dissipation device (2), the average grain size of the fine crystal layer (22) of the buffer layer (13) of Examples 1 and 2, Comparative Examples 1 and 2, and the buffer layer (20) of Example 3 The diameter, tensile strength, and average particle size of the intermetallic compound were examined. Moreover, the presence or absence of excess brazing material (brazing material pool) at the bonding interface between the insulating substrate (11) and the buffer layers (12) and (20) was examined by cross-sectional observation.

  Furthermore, 2000 cycles of 125 ° C. and −40 ° C. thermal cycle tests were performed on the brazed heat dissipation device (2), and the insulation substrate (11) and the buffer layer (13) (20) after the thermal cycle test were joined. Fatigue fracture near the interface was examined and evaluated according to the following criteria.

A: Almost no rupture is observed and very good. O: Slight rupture is observed, but it is good. X: Severe rupture These evaluation results are shown in Table 1.

  As shown in Table 1, by controlling the average grain size and tensile strength of the crystal grains as a material for the surface of the buffer layer on the insulating substrate side, excess brazing material at the bonding interface with the insulating substrate is eliminated. In addition, it was confirmed that the thermal strain can be sufficiently eliminated.

  The electronic element mounting substrate of the present invention can be suitably used for manufacturing a heat dissipation device in which an aluminum circuit layer is brazed to one surface of an insulating substrate and a heat sink is brazed to the other surface via a buffer layer.

1 ... Electronic device mounting board
2… Heat dissipation device
11… Insulating substrate
12 ... Aluminum circuit layer
13… Buffer layer (aluminum layer, solid wood)
14, 15, 17 ... brazing foil
18 ... Electronic elements
16… heat sink
20 ... Buffer layer (aluminum layer, laminated material)
21 ... base material
22 ... Fine crystal layer (layer on the insulating substrate side)

Claims (9)

An electronic element mounting substrate in which an aluminum circuit layer for mounting an electronic element is brazed to one surface of an insulating substrate and an aluminum layer is brazed to the other surface,
At least the layer on the insulating substrate side of the aluminum layer is made of aluminum or an aluminum alloy having an average grain size of 10 to 500 μm after brazing and a tensile strength of 130 N / mm ² or less. A substrate for mounting an electronic device, characterized by comprising: The aluminum layer is made of a solid material made of aluminum or aluminum alloy having an average grain size of 10 to 500 µm after brazing and a tensile strength of 130 N / mm ² or less. The electronic element mounting substrate according to 1. The aluminum layer is made of aluminum or an aluminum alloy in which the average grain size of the crystal grains after brazing on the surface of the base material on the insulating substrate side is 10 to 500 μm and the tensile strength is 130 N / mm ² or less. The electronic element mounting substrate according to claim 1, wherein the electronic element mounting substrate is formed of a laminated material in which fine crystal layers are laminated.   The electronic element mounting substrate according to claim 3, wherein the fine crystal layer has a thickness of 50 to 600 μm.   5. The electronic element mounting substrate according to claim 1, wherein the aluminum constituting the layer on the insulating substrate side of the aluminum layer is aluminum having an aluminum purity of 97.5 to 99.9 mass%.   5. The electronic element mounting device according to claim 1, wherein the aluminum alloy constituting the layer on the insulating substrate side of the aluminum layer is an aluminum alloy containing at least 0.01 to 0.8 mass% Fe. substrate. Aluminum or aluminum alloy is an electronic device mounting board according to claim 1, average particle diameter of the metal compound has been made with 3μm or less constituting the layer of the insulating substrate side of the aluminum layer.
It is a manufacturing method of the material for aluminum layers used for the substrate for electronic device mounting in any one of Claims 1-7,
An aluminum layer material characterized by performing an intermediate annealing for 1 to 8 hours at 330 to 450 ° C. during rolling of a plurality of passes on the material lump, and a reduction rate of finish rolling to 15 to 40%. Manufacturing method. 8. A heat dissipation device, wherein an aluminum layer of the insulating substrate of the electronic element mounting substrate according to claim 1 is used as a buffer layer, and a heat sink is bonded on the buffer layer.

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