JP5960405B2 - Electronic device mounting board - Google Patents

Description

  The present invention relates to an electronic device mounting substrate in which an aluminum circuit layer for mounting an electronic device on an insulating substrate is brazed, and a related technology.

  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 (see Patent Document 1).

  Further, a heat sink may be laminated on the other surface of the insulating substrate via a buffer layer for relaxing stress. Since heat sinks are required to have light weight, strength maintenance, formability, and corrosion resistance, it is common to use an aluminum alloy such as an Al-Mn alloy, and between an insulating substrate and a heat sink in the thermal cycle of an electronic device. In order to relieve the stress generated in the buffer layer, high-purity aluminum is generally used for the buffer layer. The insulating substrate and the buffer layer are brazed with an Al—Si alloy brazing material in the same manner as the joining of the metal circuit layer.

JP 2004-153075 A

  FIG. 3 is an enlarged view schematically showing the vicinity of the bonding interface between the insulating substrate (11) after brazing and the aluminum circuit layer (100). As shown in FIG. 3, the crystal grains (101) (102) (103) (104) constituting the surface of the aluminum circuit layer (100) are not necessarily arranged at the same height, but are arranged at irregular heights. Therefore, 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 aluminum circuit layer (100) and the buffer layer material brazed to the insulating substrate (11) are both high-purity aluminum, and the high-purity aluminum tends to coarsen the recrystallized grains. Therefore, the level | step difference produced between adjacent crystal grains 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 aluminum circuit layer (100) is brazed to the insulating substrate (11), the crystal grains (101) (103) that have retreated from the surface of the insulating substrate (11) to the aluminum circuit layer (100) side are formed. A brazing material pool (105) is generated, and surplus brazing material remains at the joint interface. Further, the same surplus brazing material remains at the bonding interface between the insulating substrate and the buffer layer due to the level difference of the crystal grains. If surplus brazing material remains at the joint interface, the amount of brazing material used increases, which is not preferable.

  In addition, the Al-Si alloy brazing material is harder than the high-purity aluminum constituting the aluminum circuit layer and the buffer layer, and if a brazing material pool is formed at the joining interface, stress may be easily concentrated in the thermal cycle. . 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, an object of the present invention is to provide an electronic element mounting substrate in which surplus brazing material does not remain at a bonding interface between an insulating substrate, a circuit layer made of aluminum, and a buffer layer.

  That is, this invention has the structure as described in following [1]-[8].

[1] 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,
The aluminum circuit layer is composed of a clad material in which a fine crystal layer made of aluminum or an aluminum alloy is clad on the insulating substrate side of the base material, and the average grain size of the fine crystal layer after brazing is 10 to 500 μm. An electronic device mounting board characterized by the above.

[2] 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 one of the aluminum circuit layer and the aluminum layer is formed of a clad material in which a fine crystal layer made of aluminum or an aluminum alloy is clad on the insulating substrate side of the base material, and the crystal grains of the fine crystal layer after brazing are formed. An electronic element mounting substrate having an average particle size of 10 to 500 μm.

  [3] The substrate for mounting an electronic element according to the above item 1 or 2, wherein the fine crystal layer is made of aluminum having a purity of 99 to 99.9% by mass.

  [4] The electronic element mounting substrate according to item 1 or 2, wherein the fine crystal layer includes Fe: 0.1 to 0.6% by mass, and the balance is made of an aluminum alloy including Al and inevitable impurities.

  [5] The electronic device mounting substrate according to any one of [1] to [4], wherein the thickness of the fine crystal layer is 10 to 200 μm.

  [6] The electronic element mounting substrate according to any one of [1] to [5], wherein the clad material is a brazing material clad on a fine crystal layer.

[7] A method for producing a clad material used for the electronic element mounting substrate according to any one of [1] to [6],
While performing multiple passes of rolling with the base material and the fine crystal layer material, intermediate annealing is performed at 330 to 450 ° C. for 1 to 8 hours, and the rolling reduction of finish rolling is 10 to 40%. A method for producing a clad material.

  [8] A heat dissipation device, wherein the aluminum layer of the electronic element mounting substrate described in the above item 2 is a buffer layer, and a heat sink is bonded to the buffer layer.

  In the electronic device mounting substrate described in [1], the aluminum circuit layer to be brazed to the insulating substrate is composed of a clad material in which a fine crystal layer is clad on the surface of the base material on the insulating substrate side. This fine crystal layer is refined to an average grain size of 10 to 500 μm. For this reason, since the level | step difference produced between the adjacent crystal grains in the surface of the said fine crystal layer is small, the brazing material pool produced in the joining interface with an insulating substrate also becomes small. Alternatively, no brazing material accumulation occurs. Further, since the crystal grain interface area ratio is increased by the refinement of the crystal grains, the brazing material diffuses into the crystal grain boundary, so that the brazing material remaining at the joining interface is reduced. 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 reservoir at the joining interface, it is possible to prevent stress concentration in the brazing material reservoir in the thermal cycle and to improve the thermal durability of the electronic element mounting substrate.

  In the electronic element mounting substrate according to [2], at least one of the aluminum circuit layer and the aluminum layer brazed to the insulating substrate has a fine crystal layer clad on the surface of the base material on the insulating substrate side. The fine crystal layer made of the clad material and having been brazed is refined to have an average grain size of 10 to 500 μm. For this reason, since the level | step difference produced between the adjacent crystal grains in the surface of the said fine crystal layer is small, the brazing material pool produced in the joining interface with an insulating substrate also becomes small. Alternatively, no brazing material accumulation occurs. Therefore, the amount of surplus brazing material remaining at the joint interface on the side using the clad material is suppressed, or surplus brazing material does not remain. Also, by reducing the excess brazing material remaining as a brazing material reservoir at the bonding interface with the insulating substrate, it is possible to prevent stress concentration in the brazing material reservoir in the thermal cycle and improve the thermal durability of the electronic element mounting substrate. it can.

  According to the electronic device mounting substrate described in [3] and [4], a fine crystal layer in which the average grain size of the crystal grains after brazing is 10 to 500 μm can be formed by using a material having a prescribed composition. .

  According to the electronic device mounting substrate described in [5] above, since the fine crystal layer of the clad material is 10 to 200 μm, the effect of the fine crystal layer can be sufficiently obtained.

  According to the electronic element mounting substrate described in [6] above, since the brazing material is integrated with the clad material having the fine crystal layer, the temporary assembly work during brazing is simplified.

  According to the method for producing a clad material described in [7], the average grain size of the fine crystal layer after brazing is obtained by performing intermediate annealing under the prescribed conditions and performing finish rolling at the prescribed reduction rate. A clad material having a thickness of 10 to 500 μm can be produced.

  According to the heat dissipating device described in [8] above, surplus brazing material remaining at the bonding interface on the side using the clad material at the bonding interface between the insulating substrate and the aluminum circuit layer and at the bonding interface between the insulating substrate and the aluminum layer. The amount of copper is reduced, or excess brazing material does not remain. In addition, by reducing the amount of brazing filler metal remaining at the bonding interface between the insulating substrate and the aluminum circuit layer, stress concentration on the brazing filler metal pool during the cooling / heating cycle is prevented, and the cooling durability of the heat dissipation device is improved. Can do.

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 the bonding interface between the insulating substrate after brazing and the aluminum circuit layer and the vicinity thereof in the electronic element mounting substrate according to the present invention. In the conventional electronic device mounting board | substrate, it is sectional drawing which shows the joining interface of the insulation board | substrate and aluminum circuit layer after brazing, 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 device mounting substrate (1) is stacked on the insulating substrate (11), the aluminum circuit layer (12) for mounting the electronic device on one surface of the insulating substrate (11), and the other surface. And a buffer layer (13). In the temporary assembly shown in FIG. 1, the brazing is performed between the insulating substrate (11) and the aluminum circuit layer (12) and between the aluminum circuit layer (12) and the buffer layer (13). Material foils (14) and (15) are arranged. The temporary assembly of the heat dissipating device (2) was obtained by stacking a tube-type heat sink (16) having a plurality of hollow portions on the buffer layer (13) side of the insulating substrate (11) of the electronic element mounting substrate (1). A brazing filler metal foil (17) for bonding is disposed between the buffer layer (13) and the heat sink (16).

  In the heat dissipating device (2), the temporary assembly is collectively heated by brazing, and then the electronic element (18) is mounted on the aluminum circuit layer (12) and soldered. 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 electronic element mounting substrate (1), the aluminum circuit layer (12) is a two-layer clad material in which the fine crystal layer (21) is clad on the surface of the base material (20) on the insulating substrate side. The buffer layer (13) is a layer corresponding to the aluminum layer in the present invention, and is a two-layer clad material in which the surface of the base material (22) on the insulating substrate side is clad with the fine crystal layer (23). is there. The buffer layer (13) shown in FIG. 1 is a punching metal having a plurality of circular through holes as a stress absorbing space, but the buffer layer in the present invention, that is, the aluminum layer is not limited to one having through holes.

  As the base material (20) of the aluminum circuit layer (12), it is preferable to use aluminum having high conductivity and good solderability with an electronic element, and high purity aluminum having a purity of 99.99% by mass or more is particularly recommended. it can.

  The base material of the buffer layer (13) is also preferably made of aluminum having a high thermal conductivity, and the thermal stress generated at the bonding interface between the highly rigid ceramic insulating substrate (11) and the heat sink (16) is generated. Since it is a layer for relaxing, it is preferable to use soft aluminum, and therefore high purity aluminum having a purity of 99.99% by mass or more can be recommended.

  The fine crystal layers (21) and (23) of the aluminum circuit layer (12) and the buffer layer (13) are made of aluminum or an aluminum alloy, and after brazing, the average grain size of the crystal grains is 10 to 500 μm. It becomes a more refined structure.

  FIG. 2 is an enlarged cross-sectional view schematically showing the bonding interface between the insulating substrate (11) after brazing and the fine crystal layer (21) of the aluminum circuit layer (12) and the vicinity thereof. As shown in FIG. 2, the crystal grains (31) (32) (33) (34) (35) (36) constituting the surface of the fine crystal layer (21) are not necessarily arranged at the same height. Since the crystal grains are miniaturized, the level difference between the adjacent crystal grains (dimensions in the material stacking direction) is also reduced, and the aluminum circuit layer (12) side is retracted from the surface of the insulating substrate (11). The brazing material reservoir (37) generated in the portions of the crystal grains (32) and (34) that have been reduced 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. . Although not shown in the drawings, the same applies to the bonding interface between the insulating substrate (11) and the microcrystalline layer (23) of the buffer layer (13), and the amount of the remaining brazing filler metal is suppressed, or the surplus brazing filler metal. No longer remains.

  Further, it is possible to reduce surplus brazing material remaining as a brazing material reservoir at the bonding interface between the insulating substrate (11) and the aluminum circuit layer (12) and the bonding interface between the insulating substrate (11) and the buffer layer (13). This is also preferable for preventing stress concentration in the brazing material reservoir in the cooling cycle, and can improve the cooling durability of the electronic element mounting substrate (1).

  In the fine crystal layers (21) and (23) after brazing, when the average grain size exceeds 500 μm, the above effect is small, and when the average grain size is less than 10 μm, the core material is eroded (melting of crystal grains). Therefore, it is not preferable. Therefore, the average grain size of the crystal grains after brazing the fine crystal layers (21) and (23) 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 an average grain size achieved after brazing, that is, by being subjected to brazing addition heat, the average grain size is not necessarily in the fine crystal layers (21) and (23) before brazing. It is not always within the above range. 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 material constituting the fine crystal layer (21) (23) is not limited as long as it can achieve an average particle size of 10 to 500 μm after brazing, but as one of the materials that can refine crystal grains, Aluminum having an aluminum purity of 99-99.9% by mass can be recommended. As another material, an aluminum alloy containing 0.1 to 0.6% by mass of Fe having an effect of refining crystal grains and the balance of Al and inevitable impurities can be recommended. In these materials, an impurity element other than Fe is allowed if the aluminum purity is 99% by mass or more. Examples of impurity elements other than Fe include 0.05 to 0.6 mass% Si, 0.4 mass% or less Cu, and 0.3 mass% or less Mn. Other impurity elements are permissible as long as they are 0.1% by mass or less.

  The aluminum and aluminum alloy described above have high conductivity and thermal conductivity, and have good brazing properties with the insulating substrate (11), so that the aluminum circuit layer (12) and the buffer layer (13) are partially And satisfies the conditions as a material to be brazed to the insulating substrate (11). Further, it is preferable that the microcrystalline layers (21) and (23) have low strength and can relieve stress generated at the bonding interface with the insulating substrate (11), but the above-described aluminum and aluminum alloy also satisfy the conditions.

  The thickness of the fine crystal layers (21) and (23) is preferably 10 to 200 μm in order to obtain the above-described effects sufficiently. In a thin layer having a thickness of less than 10 μm, the fine crystal layers (21) and (23) may be eroded by the brazing material and disappear, and if it exceeds 200 μm, it is too thick, making cladding difficult and uneconomical. . Particularly preferred thicknesses of the fine crystal layers (21) and (23) are 30 to 150 μm.

  The aluminum circuit layer (12) and the buffer layer (13) can also be used as a three-layer material in which a brazing material is clad on the fine crystal layers (21) and (23). Since the brazing material is integrated with the clad material having the fine crystal layer, the temporary assembly work during brazing is simplified.

  The clad material constituting the aluminum circuit layer (12) and the buffer layer (13) is hot rolled by superimposing a base material and a fine crystal layer material, or further superposing a brazing material on the fine crystal layer material. It is produced by performing multiple passes of cold rolling and finish rolling. In order to refine the crystal grains of the fine crystal layers (21) and (23) after brazing to an average grain size in the range of 10 to 500 μm, the intermediate annealing conditions and the finish rolling reduction ratio are set in this cladding material production process. It is effective to specify. The intermediate annealing is preferably held at 330 to 450 ° C. for 1 to 8 hours, particularly preferably at 370 to 420 ° C. for 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. Further, the rolling reduction of finish rolling is preferably 10 to 40%, particularly preferably 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.

  Preferred materials of the other layers 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 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. The same applies when the brazing material is clad on the aluminum circuit layer (12) and the buffer layer (13).

  The electronic element mounting substrate (1) in FIG. 1 is obtained by laminating an aluminum circuit layer (12) on one surface of an insulating substrate (11) and laminating a buffer layer (13) as an aluminum layer on the other surface. The aluminum circuit layer (12) and the buffer layer (13) are both made of a clad material obtained by cladding a fine crystal layer (21) (23) on a base material (20) (22). An electronic mounting substrate in which only one of (12) and the buffer layer (13) is made of a clad material is also included in the present invention. Further, the aluminum layer brazed to the other surface of the insulating substrate (11) is not limited to the buffer layer premised on brazing the heat sink, and the heat sink is brazed directly to the insulating substrate using the heat sink as the aluminum layer. An electronic element mounting substrate is also included in the present invention. Furthermore, the present invention includes an electronic element mounting substrate in which only an aluminum circuit layer is brazed to an insulating substrate and no aluminum layer is present on the other surface. Furthermore, an electronic element mounting board configured to use an aluminum layer brazed to the other surface of the insulating substrate (11) as a circuit layer and to mount electronic elements on both surfaces of the insulating substrate (11) is also provided. Included in the invention.

  A heat radiating 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 aluminum circuit layer and the buffer 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), a buffer layer (13), a brazing material. The foil (17) and the heat sink (16).

[Aluminum circuit layer and buffer layer]
In Examples 1 to 4, the aluminum circuit layer (12) and the buffer layer (13) were made of a two-layer clad material in which the fine crystal layers (21) and (23) were clad on one side of the base materials (20) and (22). . The material of the base materials (20) and (22) is high-purity aluminum having a purity of 99.99% by mass or more and containing 0.003% by mass of Fe as an inevitable impurity, and is common to the examples. The material of the fine crystal layers (21) and (23) was an aluminum alloy containing Fe at the concentration shown in Table 1, with the balance being Al and inevitable impurities, and different aluminum alloys were used in each example.

  In the two-layer clad material for the aluminum circuit layer (12), the thickness of the base material (20) is finally 0.6 mm and the thickness of the fine crystal layer (21) is as shown in Table 1. Further, the base material and the fine crystal layer material whose thickness was adjusted were stacked, and hot rolling, cold rolling, and finish rolling were performed. Further, in the double-layer clad material for the buffer layer (13), the thickness of the base material (22) is finally 1.6 mm, and the thickness of the fine crystal layer (23) is the thickness described in Table 1. As described above, the base material and the fine crystal layer material whose thickness was adjusted were stacked, and hot rolling, cold rolling, and finish rolling were performed. In these cladding material production steps, Examples 1, 3, and 4 were subjected to intermediate annealing under the conditions shown in Table 1 before finish rolling, and Example 2 was not subjected to intermediate annealing. Moreover, the finish rolling of each Example was implemented with the rolling reduction shown in Table 1.

  The produced two-layer clad material 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). In addition, the double-layer clad material for the buffer layer (13) was cut into 28 mm × 28 mm, and further subjected to cutting to form 12 circular through holes with a diameter of 2 mm as a temporary assembly of the heat dissipation device (2). used.

  On the other hand, the aluminum circuit layer of the comparative example was obtained by cutting a 6 mm thick solid rolled plate made of high-purity aluminum having the same composition as the base material (20) (22) of the double-layer clad material into 28 mm × 28 mm. Used for temporary assembly of heat dissipation device. The buffer layer is a 1.6 mm thick solid rolled plate made of high-purity aluminum having the same composition as the base material (20) (22) of the two-layer clad material, and is further cut into 28 mm × 28 mm. What formed 12 circular holes with a diameter of 2 mm was used for temporary assembly of the heat dissipation device.

[Other parts]
The members excluding the aluminum circuit layer and the buffer layer 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 4 and Comparative Example were vacuum brazed at 600 ° C. for 20 minutes in a vacuum of 7 × 10 ⁻⁴ Pa.

  For the brazed heat dissipation device (2), the average grain size of the aluminum circuit layer (12) and the fine crystal layers (21) and (23) of the buffer layer (13) of Examples 1 to 4, and the comparative example When the average grain size of the crystal grains of the aluminum circuit layer and the buffer layer made of high-purity aluminum was examined, the values shown in Table 1 were obtained. In addition, while observing the presence or absence of excess brazing material (brazing material reservoir) at the bonding interface between the insulating substrate (11) and the aluminum circuit layer (12), and the bonding interface between the insulating substrate (11) and the buffer layer (13), The durability in the cooling and heating cycle was evaluated by the following method. The evaluation results are shown in Table 1.

[Cooling durability test]
The thermal cycle test (125 ° C.−40 ° C.) was performed 2000 cycles, and the bonding area of the bonding interface between the insulating substrate (11) (AlN), the aluminum circuit layer (12) (Al), and the buffer layer (13) (Al) was determined. Measurement was performed with an ultrasonic flaw detector, and the area ratio of the peeled portion was measured and evaluated. The case where cracks occurred in AlN or the peeling at the AlN / Al bonding interface peeled 5% or more with respect to the bonding area was Δ, the case where it was 3% or more and less than 5%, and the case where it was less than 3%.

  As shown in Table 1, in the brazed heat dissipation device, the fine crystal layer of the two-layer clad material used in Examples 1 to 4 compared to the high-purity aluminum constituting the aluminum circuit layer and the buffer layer of the comparative example The crystal grains are extremely fine. And in Examples 1-4, although the excess brazing material was not recognized by the joining interface of an insulating substrate, an aluminum circuit layer, and a buffer layer, the excess brazing material was recognized in the comparative example. Moreover, Examples 1-4 confirmed that the durability in a cooling-heat cycle was improving rather than the comparative example.

  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)
14, 15, 17 ... brazing foil
18 ... Electronic elements
16… heat sink
20, 22 ... Base material
21, 23 ... Fine crystal layer
31, 32, 33, 34, 35, 36, 101, 102, 103, 104 ... crystal grains
37, 105 ... Brazing material reservoir (excess brazing material)
100 ... Aluminum circuit layer (high purity aluminum)

Claims (11)

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,
The aluminum circuit layer and the base material, the insulating substrate side of the base material is composed of a clad material with fine crystal layer, the microcrystalline layer is Fe: it includes 0.1 to 0.6 mass%, the balance being A substrate for mounting an electronic device, comprising an aluminum alloy composed of Al and inevitable impurities , wherein an average particle size of crystal grains of the fine crystal layer after brazing is 10 to 500 μm. 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,
Wherein at least one of aluminum circuit layer and aluminum layer, and the base material, the insulating substrate side of the base material is composed of a clad material with fine crystal layer, the microcrystalline layer is Fe: 0.1 to 0.6 mass %, And the balance is made of an aluminum alloy consisting of Al and inevitable impurities, and the average grain size of the crystal grains of the fine crystal layer after brazing is 10 to 500 μm . Electronic device mounting board according to claim 1 or 2 thickness of the fine crystal layer is 10 to 200 [mu] m. The clad material, the base material, and the base material of the insulating substrate side of the fine crystal layer of the fine crystal layer side of the base material opposite a three-layer clad material of the brazing material is as claimed in claim 1 to 3 of The electronic device mounting substrate according to any one of the above. A method for producing a clad material constituting an aluminum circuit layer of 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,
While performing multiple passes of rolling with the base material and the fine crystal layer material, intermediate annealing is performed at 330 to 450 ° C. for 1 to 8 hours, and the rolling reduction of finish rolling is 10 to 40%. A method for producing a clad material.   Construct at least one of the aluminum circuit layer and the aluminum layer of 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 A method for producing a clad material,
  While performing multiple passes of rolling with the base material and the fine crystal layer material, intermediate annealing is performed at 330 to 450 ° C. for 1 to 8 hours, and the rolling reduction of finish rolling is 10 to 40%. A method for producing a clad material.   The method for producing a clad material according to claim 5 or 6, wherein the fine crystal layer material is made of aluminum having a purity of 99 to 99.9 mass%.   The method for producing a clad material according to claim 5 or 6, wherein the fine crystal layer material includes Fe: 0.1 to 0.6 mass%, and the balance is made of an aluminum alloy including Al and inevitable impurities.   The method for producing a clad material according to any one of claims 5 to 8, wherein the thickness of the fine crystal layer material after finish rolling is 10 to 200 µm.   The method for manufacturing a clad material according to any one of claims 5 to 9, wherein a plurality of passes of rolling are performed by further overlapping a brazing material on the fine crystal layer material side.   The heat dissipation device, wherein the aluminum layer of the electronic element mounting substrate according to claim 2 is a buffer layer, and a heat sink is bonded to the buffer layer.

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