JP5856801B2 - Electronic device mounting substrate and heat dissipation device - Google Patents
Electronic device mounting substrate and heat dissipation device Download PDFInfo
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- JP5856801B2 JP5856801B2 JP2011230869A JP2011230869A JP5856801B2 JP 5856801 B2 JP5856801 B2 JP 5856801B2 JP 2011230869 A JP2011230869 A JP 2011230869A JP 2011230869 A JP2011230869 A JP 2011230869A JP 5856801 B2 JP5856801 B2 JP 5856801B2
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- 239000000758 substrate Substances 0.000 title claims description 125
- 230000017525 heat dissipation Effects 0.000 title claims description 24
- 239000000463 material Substances 0.000 claims description 110
- 229910052782 aluminium Inorganic materials 0.000 claims description 99
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 98
- 238000005219 brazing Methods 0.000 claims description 93
- 239000013078 crystal Substances 0.000 claims description 84
- 238000005096 rolling process Methods 0.000 claims description 29
- 229910000838 Al alloy Inorganic materials 0.000 claims description 26
- 238000000137 annealing Methods 0.000 claims description 14
- 239000002648 laminated material Substances 0.000 claims description 13
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 10
- 239000011343 solid material Substances 0.000 claims description 10
- 150000002736 metal compounds Chemical class 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 description 15
- 239000002184 metal Substances 0.000 description 15
- 230000000694 effects Effects 0.000 description 13
- 229910000765 intermetallic Inorganic materials 0.000 description 11
- 239000011888 foil Substances 0.000 description 10
- 239000000945 filler Substances 0.000 description 9
- 238000001816 cooling Methods 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 6
- 239000000956 alloy Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 4
- 238000005098 hot rolling Methods 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229910021364 Al-Si alloy Inorganic materials 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 3
- 238000005097 cold rolling Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000005304 joining Methods 0.000 description 3
- 238000007670 refining Methods 0.000 description 3
- 229910018131 Al-Mn Inorganic materials 0.000 description 2
- 229910018125 Al-Si Inorganic materials 0.000 description 2
- 229910018461 Al—Mn Inorganic materials 0.000 description 2
- 229910018520 Al—Si Inorganic materials 0.000 description 2
- 229910018566 Al—Si—Mg Inorganic materials 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000010292 electrical insulation Methods 0.000 description 2
- 230000003628 erosive effect Effects 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910000861 Mg alloy Inorganic materials 0.000 description 1
- 229910000914 Mn alloy Inorganic materials 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000011162 core material Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 0.000 description 1
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Description
本発明は、絶縁基板の一方の面に電子素子を搭載するためのアルミニウム回路層がろう付けされ、他方の面にアルミニウム層がろう付された電子素子搭載用基板、およびこの電子素子搭載用基板を用いた放熱装置に関する。 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.
電子素子搭載用基板として、絶縁基板の一面側に金属回路層が接合したものが知られている。かかる基板において、絶縁基板は電気絶縁性が優れていることはもとより、熱伝導性が良く放熱性が優れているセラミックが用いられ、前記金属回路層は導電性が高くかつ前記絶縁基板と接合可能な金属として高純度アルミニウムが用いられ、これらはＡｌ−Ｓｉ系合金ろう材によってろう付される。また、前記絶縁基板の他方の面にはヒートシンクを積層して放熱装置が作製されることがある（特許文献１参照）。 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).
前記ヒートシンクは軽量性、強度維持、成形性、耐食性が要求されることから、Ａｌ−Ｍｎ系合金等の強度の高いアルミニウム合金を用いられ、前記絶縁基板とヒートシンクとの間に発生する応力を緩和するために、緩衝層としてのアルミニウム層を介してヒートシンクが接合される。また、前記放熱装置は絶縁基板の両面にアルミニウム回路層と緩衝層を介してヒートシンクを接合した非対称な形状であり、冷熱サイクルにおいて非対称形状に起因する熱ひずみが緩衝層に加わることで絶縁基板の割れや接合界面の剥がれへの影響が大きくなるという背景がある。このため、前記緩衝層は軟質で応力緩和力の大きい高純度アルミニウムが用いられ、前記金属回路層の接合と同じく、絶縁基板と緩衝層はＡｌ−Ｓｉ系合金ろう材によってろう付けされている。 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.
図４は、ろう付後の絶縁基板（11）と緩衝層（100）との接合界面の近傍を拡大して模式的に示した図である。図４に示すように、緩衝層（100）の表面を構成する結晶粒（101）（102）（103）（104）は必ずしも同じ高さで並んでいるのではなく不揃いの高さで並んでおり、隣接する結晶粒との間に段差が生じて絶縁基板（11）との間に隙間が生じる。結晶粒が大きくなると、前記隙間は絶縁基板（11）の表面に平行な方向の寸法が大きくなるだけでなく、前記段差（材料の積層方向の寸法）も大きくなることがわかっている。上述したように、絶縁基板（11）にろう付される緩衝層（100）の材料は高純度アルミニウムであって、高純度アルミニウムは再結晶粒が粗大化する傾向があるので隣接する結晶粒との間に生じる段差も大きくなっている。つまりは、結晶粒径が大きいことにより、結晶粒径の細かいものと比較して段差による体積が多くなることとなる。このため、前記緩衝層（100）を絶縁基板（11）にろう付すると、絶縁基板（11）の表面から緩衝層（100）側に退いた結晶粒（101）（103）の部分にろう材溜まり（105）が生じて余剰ろう材が接合界面に残存することになる。 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.
また、Ａｌ−Ｓｉ系合金ろう材は緩衝層を構成する高純度アルミニウムよりも硬質であり、接合界面に硬いろう材溜まりが生じると冷熱サイクルにおいて応力が集中しやすくなるおそれがある。また、放熱装置が絶縁基板の両面で非対称な形状である以上、非対称形状に起因する熱ひずみの発生を防ぐ方策が要求される。このため、電子素子搭載用基板の冷熱耐久性の向上を図るためにも接合界面に余剰ろう材が残存しないこと、あるいは残存する余剰ろう材量が少ないことが好ましい。 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.
本発明は上述した背景技術に鑑み、絶縁基板の両面にアルミニウム回路層とアルミニウム層がろう付された電子素子搭載用基板であって、絶縁基板とアルミニウム層との接合界面に余剰ろう材が残存せず、かつ非対称形状に起因する熱ひずみを低減しうる電子素子搭載用基板およびこの電子素子搭載用基板を用いた放熱装置の提供を目的とする。 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.
即ち、本発明は下記［１］〜［９］に記載の構成を有する。 That is, the present invention has the configurations described in [1] to [9] below.
［１］絶縁基板の一方の面に電子素子を搭載するアルミニウム回路層がろう付され、他方の面にアルミニウム層がろう付された電子素子搭載用基板であって、
前記アルミニウム層の少なくとも絶縁基板側の層が、ろう付後の結晶粒の平均粒径が１０〜５００μｍとなされ、かつ引張強さが１３０Ｎ／ｍｍ２以下となされたアルミニウムまたはアルミニウム合金で構成されていることを特徴とする電子素子搭載用基板。
[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］前記アルミニウム層は、ろう付後の結晶粒の平均粒径が１０〜５００μｍとなされ、かつ引張強さが１３０Ｎ／ｍｍ２以下となされたアルミニウムまたはアルミニウム合金からなる無垢材で構成されている前項１に記載の電子素子搭載用基板。
[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
［３］前記アルミニウム層は、母材の絶縁基板側の面にろう付後の結晶粒の平均粒径が１０〜５００μｍとなされ、かつ引張強さが１３０Ｎ／ｍｍ２以下となされたアルミニウムまたはアルミニウム合金からなる微細結晶層が積層された積層材で構成されている前項１に記載の電子素子搭載用基板。
[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
［４］前記微細結晶層の厚さが５０〜６００μｍである前項３に記載の電子素子搭載用基板。 [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］前記アルミニウム層の絶縁基板側の層を構成するアルミニウムは、アルミニウム純度が９７．５〜９９．９質量％のアルミニウムである前項１〜４のいずれかに記載の電子素子搭載用基板
［６］前記アルミニウム層の絶縁基板側の層を構成するアルミニウム合金は、少なくとも０．０１〜０．８質量％のＦｅを含有するアルミニウム合金である前項１〜４のいずれかに記載の電子素子搭載用基板。
[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］前記アルミニウム層の絶縁基板側の層を構成するアルミニウムまたはアルミニウム合金は金属化合物の平均粒径が３μｍ以下となされている前項１〜６のいずれかに記載の電子素子搭載用基板。 [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］前項１〜７のいずれかに記載の電子素子搭載用基板に用いるアルミニウム層用材料の製造方法であって、
材料塊に対して複数パスの圧延を行う間に、３３０〜４５０℃で１〜８時間の中間焼鈍を行い、仕上げ圧延の圧下率を１５〜４０％とすることを特徴とするアルミニウム層用材料の製造方法。
[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］前項１〜７のいずれかに記載の電子素子搭載用基板の絶縁基板のアルミニウム層を緩衝層とし、この緩衝層上にヒートシンクが接合されていることを特徴とする放熱装置。 [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.
上記［１］に記載の電子素子搭載用基板は、絶縁基板の一方の面にアルミニウム回路層がろう付され、他方の面にろう付されたアルミニウム層の少なくとも絶縁基板側の層は、結晶粒の平均粒径が１０〜５００μｍに微細化され、かつ引張強さが１３０Ｎ／ｍｍ２以下となされている。 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.
前記アルミニウム層は、結晶粒の微細化により、表面において隣接する結晶粒との間に生じる段差が小さいので、絶縁基板との接合界面に生じるろう材溜まりも小さくなる。あるいは、ろう材溜まりが発生しなくなる。また、結晶粒の微細化によって結晶粒界面積率が高くなるので、ろう材が結晶粒界に拡散し接合界面に残存するろう材が減少する。これらによって、接合界面に残存する余剰ろう材の量が抑えられ、あるいは余剰ろう材が残存しなくなる。そして、接合界面にろう材溜まりとして残存する余剰ろう材を減らすことによって冷熱サイクルにおけるろう材溜まりへの応力集中を防ぎ、かつ引張強さが１３０Ｎ／ｍｍ２以下となされていることで十分な応力緩和力を得て非対称形状に起因する熱ひずみを低減することができるので、電子素子搭載用基板の冷熱耐久性を向上させることができる。 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.
上記［２］に記載の電子素子搭載用基板によれば、結晶粒の平均粒径および引張強さが規定された無垢材からなるアルミニウム層によって上記の冷熱耐久性向上効果を得ることができる。 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.
上記［３］に記載の電子素子搭載用基板によれば、母材の絶縁基板側の面に結晶粒の平均粒径および引張強さが規定された微細結晶層を積層した積層材からなるアルミニウム層によって上記の冷熱耐久性向上効果を得ることができる。 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.
上記［４］に記載の電子素子搭載用基板によれば、積層材の微細結晶層の厚さが５０〜６００μｍに設定されているので、接合界面における余剰ろう材の低減効果および結晶粒界へのろう材拡散効果を十分に得て、上記の冷熱耐久性向上効果を得ることができる。 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.
上記［５］［６］に記載の電子素子搭載用基板によれば、規定された組成の材料を用いることによって、ろう付後の結晶粒の平均粒径が１０〜５００μｍであり、かつ１３０Ｎ／ｍｍ２以下の引張強さを有するアルミニウム層を形成できる。 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.
上記［７］に記載の電子素子搭載基板によれば、アルミニウム回路層中の金属間化合物の平均粒径が３μｍ以下となされているため、結晶粒の平均粒径を１０〜５００μｍに制御することが容易である。 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.
上記［８］に記載のアルミニウム層用材料の製造方法によれば、規定された条件で中間焼鈍を行い、かつ規定された圧下率で仕上げ圧延を行うことにより、ろう付後に結晶粒の平均粒径が１０〜５００μｍとなり、かつ１３０Ｎ／ｍｍ２以下の引張強さを有する材料を作製することができる。 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.
上記［９］に記載の放熱装置によれば、電子素子搭載用基板の緩衝層の少なくとも絶縁基板側の層は結晶粒が微細化されかつ引張強さが規制されている。このため、絶縁基板と緩衝層との接合界面に残存する余剰ろう材の量が抑えられ、あるいは余剰ろう材が残存しなくなる。そして、接合界面にろう材溜まりとして残存する余剰ろう材を減らすことによって冷熱サイクルにおけるろう材溜まりへの応力集中を防ぎ、かつ引張強さが１３０Ｎ／ｍｍ２以下となされていることで十分な応力緩和力を得て非対称形状に起因する熱ひずみを低減することができるので、放熱装置の冷熱耐久性を向上させることができる。 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.
図１は本発明の電子素子搭載用基板の一実施形態と、この電子素子搭載用基板を用いて作製する放熱装置の仮組物を、構成部材が積層する方向で切断した断面で示している。 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. .
電子素子搭載用基板（1）は、絶縁基板（11）と、この絶縁基板（11）の一方の面に重ねられた電子素子搭載用のアルミニウム回路層（12）とにより構成されている。図１の仮組物においては、前記絶縁基板（11）とアルミニウム回路層（12）との間にこれらを接合するためのろう材箔（14）が配置されている。また、放熱装置（2）の仮組物は、前記電子素子搭載用基板（1）の絶縁基板（11）の他方の面に緩衝層（13）を介して複数の中空部を有するチューブ型のヒートシンク（16）を重ねたものであり、絶縁基板（11）と緩衝層（13）との間、および緩衝層（13）との間ヒートシンク（16）との間には接合用のろう材箔（15）（17）が配置されている。前記緩衝層（13）は、絶縁基板（11）に対してアルミニウム回路層（12）の反対面にろう付される層であり、本発明におけるアルミニウム層に対応する。 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.
前記放熱装置（2）は前記仮組物を一括してろう付加熱され、その後アルミニウム回路層（12）上に電子素子(18)がはんだ付される。ろう付後の放熱装置（2）において、アルミニウム回路層（12）がろう付された絶縁基板（11）とヒートシンク（16）とは緩衝層（13）を介して熱的に結合され、電子素子（18）が発する熱はヒートシンク（16）に排熱される。 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).
本発明において、電子素子搭載用基板のアルミニウム層（緩衝層）は少なくとも絶縁基板側の層が結晶粒の平均粒径および引張強さが規定されたアルミニウムまたはアルミニウム合金からなる。図１に示した緩衝層（13）は前記アルミニウムまたはアルミニウム合金からなる無垢材であり、図３に示した緩衝層（20）は母材（21）の絶縁基板（11）側の面に前記アルミニウムまたはアルミニウム合金からなる微細結晶層（22）を積層した積層材であり、いずれも本発明の条件を満たしている。 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.
まず、無垢材からなる緩衝層（13）について詳述する。 First, the buffer layer (13) made of a solid material will be described in detail.
前記緩衝層（13）は、ろう付後に結晶粒の平均粒径が１０〜５００μｍとなされ、高純度アルミニウムよりも微細化された結晶組織を有する。 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.
図２は、ろう付後の絶縁基板（11）と緩衝層（13）との接合界面およびその近傍を拡大して模式的に示した断面図である。図２に示すように、緩衝層（13）の表面を構成する結晶粒（31）（32）（33）（34）（35）（36）が必ずしも同じ高さで並んではいなくても、結晶粒が微細化されていることで隣接する結晶粒との間に生じる段差（材料の積層方向の寸法）も小さくなり、絶縁基板（11）の表面から緩衝層（13）側に退いた結晶粒（32）（34）の部分に生じるろう材溜まり（37）も小さくなる。あるいは、段差が無くなってろう材溜まりが発生しなくなる。 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.
結晶粒が小さくなると隣接する結晶粒との間に生じる段差が小さくなる理由は、以下のとおりである。 The reason why the level difference between adjacent crystal grains becomes smaller as the crystal grains become smaller is as follows.
結晶方位の異なる結晶粒は方向によって線膨張係数が異なる。このため、結晶方位の異なる結晶粒が隣接していると、それらの結晶粒はろう付中に線膨張係数の差によって相互に回転力または変形力を受ける。さらに、ろう付中の材料に加わる荷重や摩擦力等は結晶粒を回転させる力または変形させる力となって作用する。そして、結晶粒の回転角度が同じであっても結晶粒が大きくなるほどずれは大きくなり、結晶粒が小さくなるほどずれは小さくなる。また変形力を受ける場合おいても、大きい結晶粒で変形力を受けることで粒界でのずれが大きくなり、小さい結晶粒の粒界ではずれが小さくなる。隣接する結晶粒の段差はこのようなずれによって生じるために、結晶粒が小さくなるほど段差が小さくなる。 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.
従って、結晶粒が小さくなると、接合界面に残存する余剰ろう材の量が抑えられ、あるいは余剰ろう材が残存しなくなって、ろう材の使用量が抑えられる。また、結晶粒が細かいために結晶粒界面積率が高くなるので、結晶粒界に拡散するろう材量が増えることによっても絶縁基板（11）との接合界面に残存する余剰ろう材が減少する。 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. .
また、前記絶縁基板（11）と緩衝層（13）との接合界面にろう材溜まりとして残存する余剰ろう材を減らすことは、冷熱サイクルにおいてろう材溜まりへの応力集中を防ぐ上でも好ましいことであり、電子素子搭載用基板（1）の冷熱耐久性を向上させることができる。 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.
ろう付後の緩衝層（13）において結晶粒の平均粒径が５００μｍを超えると上記効果が少なく、平均粒径が１０μｍ未満ではろう付時にろう材による侵食が大きくなって接合性が低下するおそれがある。よって、本発明における緩衝層（13）のろう付後の結晶粒の平均粒径は１０〜５００μｍとする。好ましい結晶粒の平均粒径は４０〜４５０μｍである。前記結晶粒の平均粒径はろう付後、即ちろう付加熱を受けることによって達成される平均粒径であるから、ろう付前の緩衝層（13）においては必ずしも平均粒径が上記範囲内であるとは限らない。本発明はろう付条件を限定するものではないが、ろう付条件として５９０〜６２０℃で５〜３０分の加熱を推奨できる。 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.
前記緩衝層（13）は、結晶粒の平均粒径とともに引張強さが１３０Ｎ／ｍｍ２以下に規定されている。１３０Ｎ／ｍｍ２以下の引張強さに規定することで十分な応力緩和力を得て非対称形状に起因する熱ひずみを低減することができる。引張強さの低い材料の方が高い応力緩和力が得られるので本発明は引張強さの下限値を規定するものではないが、結晶粒の平均粒径が１０〜５００μｍなる条件を満たす材料は４５Ｎ／ｍｍ２以上の引張強さを有することが多く、材料選定の容易性という観点から４５Ｎ／ｍｍ２以上の引張強さを推奨できる。好ましい引張強さは４５〜１２０Ｎ／ｍｍ２であり、特に好ましい引張強さは５０〜１１０Ｎ／ｍｍ２である。 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 .
以上より、絶縁基板（11）と緩衝層（13）との接合界面にろう材溜まりとして残存する余剰ろう材を減らすことによって冷熱サイクルにおけるろう材溜まりへの応力集中を防ぎ、かつ緩衝層（13）の引張強さが１３０Ｎ／ｍｍ２以下となされていることで十分な応力緩和力を得て非対称形状に起因する熱ひずみを低減することができるので、電子素子搭載用基板（1）および放熱装置（2）の冷熱耐久性を向上させることができる。 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.
前記緩衝層（13）における結晶粒の平均粒径および引張強さを制御する要因として、緩衝層（13）を構成する材料の化学組成、材料中の金属間化合物の粒径、材料の製造条件を挙げることができる。 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.
前記緩衝層（13）を構成する材料の一つとして、アルミニウム純度が９７．５〜９９．９質量％のアルミニウムを推奨できる。アルミニウム純度が９９．９質量％を超えて高くなると結晶粒が粗大化するおそれがあり、アルミニウム純度が９７．５質量％未満では引張強さが高くなって１３０Ｎ／ｍｍ２以下の引張強さを実現することが困難になる。特に好ましいアルミニウム純度は９７．５〜９９質量％である。また、前記緩衝層（13）を構成するもう一つの材料として、結晶粒を微細化する効果のあるＦｅを０．０１〜０．８質量％含有するアルミニウム合金を推奨できる。Ｆｅ濃度が０．０１質量％未満では結晶粒の微細化効果が少ない。一方、０．８質量％を添加すれば十分な結晶粒微細化効果が得られるので、０．８質量％を超えるＦｅの添加は不経済である。特に好ましいＦｅ濃度は０．１〜０．６質量％である。前記アルミニウム合金の残部はＡｌおよび不可避不純物であるが、少なくとも０．０１〜０．８質量％のＦｅを含有していれば結晶粒微細化効果が得られるので、アルミニウム純度が９７．５質量％以上であればＦｅ以外の不純物元素を含有することが許容される。 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.
前記緩衝層（13）を構成するアルミニウムまたはアルミニウム合金において、金属間化合物の平均粒径が３μｍ以下であることが好ましい。金属間化合物の平均粒径が３μｍを超えると結晶粒を所定の大きさに制御することが困難になる傾向があり、また大きな金属間化合物が絶縁基板（11）と緩衝層（13）との接合界面に多く存在する状態はろう付による接合信頼性を維持する上で好ましいことではない。このため、結晶粒制御の容易性および接合信頼性の観点から、金属間化合物の平均粒径は３μｍ以下が好ましい。特に好ましい金属間化合物の平均粒径は１μｍ以下である。 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.
上述したアルミニウムおよびアルミニウム合金は、高い導電性および熱伝導性を有し、かつ絶縁基板（11）とのろう付性が良好であるから、絶縁基板（11）にろう付される材料としての条件を満たしている。 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.
また、図１に示した緩衝層（13）は応力吸収空間として複数の円形貫通穴を有するパンチングメタルであるが、本発明において緩衝層における応力吸収空間の有無や形状は任意に設定することができる。 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.
前記緩衝層（13）は薄板状であり、例えば、材料塊に対して熱間圧延、冷間圧延、仕上げ圧延の複数パスの圧延を行うことにより作製される。結晶粒の平均粒径を１０〜５００μｍの範囲に微細化しかつ１３０Ｎ／ｍｍ２以下の引張強さを発現させ、かつ金属間化合物の平均粒径を１μｍ以下に制御するには、この作製工程において中間焼鈍条件および仕上げ圧延の圧下率を規定することが有効である。中間焼鈍は３３０〜４５０℃で１〜８時間保持することが好ましい。３３０℃未満または１時間未満の焼鈍では結晶粒が過度に微細化されるおそれがあり、４５０℃超または８時間超の焼鈍はエネルギーコストの点で不経済である。中間焼鈍の特に好ましい条件は３５０〜４２０℃で２〜６時間である。また、前記条件による中間焼鈍を行う時期は熱間圧延後もしくは仕上げ圧延前が好ましい。仕上げ圧延の圧下率は１５〜４０％が好ましい。１５％未満の圧下率では再結晶せずろう付時に侵食が大きくなるおそれがあり、４０％超の圧下率では結晶粒が過度に小さくなるおそれがある。特に好ましい圧下率は１５〜３０％である。仕上げ圧延は単パス、複数パスのどちらで行っても良く、仕上げ圧延を複数パスで行う場合の圧下率は合計の圧下率である。 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.
余剰ろう材および非対称形状に起因する熱ひずみは絶縁基板と緩衝層との接合界面で生じる問題であるから、緩衝層は少なくとも絶縁基板側の層における結晶粒径および引張強さが上述した範囲内となされた材料で構成されていれば、接合界面で生じるこれらの問題を解消することができる。従って、緩衝層として図１の無垢材（13）の他に、図３に示した積層材（20）を用いることができる。 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.
図３に示した緩衝層（20）は、母材（21）の絶縁基板（11）側の面に微細結晶層（22）が積層された積層材であり、微細結晶層（22）は上述した無垢材による緩衝層（13）と同じく、ろう付後の結晶粒の平均粒径が１０〜５００μｍとなされ、かつ引張強さが１３０Ｎ／ｍｍ２以下となされたアルミニウムまたはアルミニウム合金で形成されている。このような積層材はクラッド圧延材であっても良いし、２つの層をろう付したろう付積層材であっても良い。 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.
前記緩衝層（20）において、母材（21）の材料は微細結晶層（22）よりも軟質で応力緩和力の大きい材料で形成されていることが好ましく、アルミニウム純度が９９．９９質量％以上の高純度アルミニウムを推奨できる。また、前記微細結晶層（22）の厚さ（ｔ）は接合界面における余剰ろう材の低減効果および結晶粒界へのろう材拡散効果を得るためには５０μｍ以上であることが好ましい。また、厚さ（ｔ）が６００μｍあれば十分に効果が得られるので、それ以上厚くするのは不経済である。特に好ましい微細結晶層（22）の厚さ（ｔ）は１５０〜４００μｍである。前記母材（21）の厚さに制限はなく適宜設定すれば良い。 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.
前記緩衝層（20）がクラッド圧延材の場合は、周知のクラッド圧延材の製造方法に従い、母材材料と微細結晶層材料とを重ねて複数パスの圧延を行うことにより作製する。この工程において、無垢材の製造工程と同じく、３３０〜４５０℃で１〜８時間の中間焼鈍を行い、１５〜４０％の圧下率で仕上げ圧延を行うことによって微細結晶層（22）の結晶粒の平均粒径、引張強さ、金属間化合物の平均粒径を本発明が規定する範囲内に制御することができる。 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.
また、前記緩衝層（20）がろう付積層材である場合は、所定厚さに加工した母材（21）と微細結晶層（22）との間にろう材箔を挟んでろう付するか、微細結晶層（22）を心材としてろう材層をクラッドしたブレージングシートを作成し、このブレージングシートを母材（21）にろう付する方法を推奨できる。前者の場合は微細結晶層を作製する工程でにおいて、後者の場合はブレージングシートを作製する工程において、無垢材の製造工程と同じく、３３０〜４５０℃で１〜８時間の中間焼鈍を行い、１５〜４０％の圧下率で仕上げ圧延を行うことによって微細結晶層（22）の結晶粒の平均粒径、引張強さ、金属間化合物の平均粒径を本発明が規定する範囲内に制御することができる。また、前記ろう材はＡｌ−Ｓｉ系合金、Ａｌ−Ｓｉ−Ｍｇ系合金等のろう材を用いる。上述したろう付積層材のろう付は、図１に示した電子素子搭載基板（1）、あるいは放熱装置（2）を仮組みする際に他の部材とともに一括してろう付することができる。 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.
前記電子素子搭載用基板（1）および放熱装置（2）を構成する他の部材の好ましい材料は以下のとおりである。 Preferred materials for the other members constituting the electronic element mounting substrate (1) and the heat dissipation device (2) are as follows.
絶縁基板（11）を構成する材料としては、窒化アルミニウム、酸化アルミニウム、窒化ケイ素、酸化ジルコニウム、炭化ケイ素等のセラミックを例示できる。これらのセラミックは電気絶縁性が優れていることはもとより、熱伝導性が良く放熱性が優れている点で推奨できる。 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.
アルミニウム回路層（12）は、導電性が高くかつ絶縁基板（11）との接合界面に発生する応力を緩和できるアルミニウムを用いることが好ましく、前記緩衝層（13）と同等のアルミニウムまたはアルミニウム合金、あるいは高純度アルミニウムを使用することが好ましい。 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.
ヒートシンク（16）を構成する金属は、軽量性、強度維持、成形性、耐食性に優れた材料を用いることが好ましく、これらの特性を有するものとしてＡｌ−Ｍｎ系合金等のアルミニウム合金を推奨できる。ヒートシンク（16）は緩衝層（13）側の外面がフラットであれば緩衝層（13）と広い面積でろう付して高い放熱性能が得られるので、緩衝層（13）側の面以外の外部形状や内部形状は問わない。ヒートシンクの他の形状として、平板、平板の他方の面にフィンをろう付したヒートシンク、平板の他方の面にフィンを立設したヒートシンク、中空部内にフィンを設けたチューブ型ヒートシンク等を例示できる。 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.
前記ろう材箔（14）（15）（17）の材料は限定されないが、上述したアルミニウム回路層（12）、絶縁基板（11）、緩衝層（13）、ヒートシンク（16）の材料の接合に好適なろう材としてＡｌ−Ｓｉ系合金、Ａｌ−Ｓｉ−Ｍｇ系合金を推奨できる。 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.
図１に参照される積層構造の電子素子搭載用基板（1）を含む放熱装置（2）を、緩衝層およびアルミニウム回路層の材料を変えて作製した。前記放熱装置（2）において積層した部材は、積層順に、アルミニウム回路層（12）、ろう材箔（14）、絶縁基板（11）、ろう材箔（15）、緩衝層（13）（20）、ろう材箔（17）、ヒートシンク（16）である。使用した部材の詳細は以下のとおりである。 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.
［緩衝層］
実施例１、２、比較例１、２の緩衝層（13）は図１に参照される無垢材で構成され、それぞれ表１に記載した濃度のＦｅを含み、残部がＡｌおよび不可避不純物からなるアルミニウム合金を用いた。緩衝層（13）用材料として、材料塊に対し、熱間圧延、冷間圧延、仕上げ圧延を施し、厚さ１．６ｍｍの薄板を作製した。これらの薄板を作製する工程において、仕上げ圧延前で板厚が２．１３ｍｍのときに４２０℃×４時間の中間焼鈍を行い、仕上げ圧延を２５％の圧下率で実施した。
[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%.
作製した緩衝層（13）用の薄板は２８ｍｍ×２８ｍｍに切断し、さらに切削加工を施して直径２ｍｍの円形の１２個の貫通穴を形成したものを放熱装置（2）の仮組みに使用した。 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). .
実施例３の緩衝層（20）は図３に参照される積層材の薄板で構成され、母材（21）の材料としてＡｌ純度が９９．９９質量％の高純度アルミニウムを用い、微細結晶層（22）の材料として表１に記載したＦｅを含み、残部がＡｌおよび不可避不純物からなるアルミニウム合金を用いた。前記積層材はクラッド圧延材であり、最終的に母材（21）の厚さが１．３ｍｍ、微細結晶層（22）が３００μｍとなるように厚さを調節した母材材料と微細結晶層材料を重ね、複数パスの圧延を施して厚さ１．６ｍｍのクラッド圧延材を作製した。このクラッド圧延材を作製する工程において、仕上げ圧延前で板厚が２．１３ｍｍのときに４２０℃×４時間の中間焼鈍を行い、仕上げ圧延を２５％の圧下率で実施した。 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%.
作製した緩衝層（20）用のクラッド圧延材は２８ｍｍ×２８ｍｍに切断し、さらに切削加工を施して直径２ｍｍの円形の１２個の貫通穴を形成したものを放熱装置（2）の仮組みに使用した。 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.
［アルミニウム回路層］
アルミニウム回路層（12）の材料として、実施例１、２、比較例１、２はそれぞれの緩衝層（13）と同じ組成のアルミニウム合金を用い、実施例３は緩衝層（20）の微細結晶層（22）と同じ組成のアルミニウム合金を用いた。
[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.
アルミニウム回路層（12）用材料として、材料塊に対し、熱間圧延、冷間圧延、仕上げ圧延を施し、厚さ０．６ｍｍの薄板を作製した。これらの薄板を作製する工程において、緩衝層用材料と同じく、４２０℃×４時間の中間焼鈍を行い、仕上げ圧延を２５％の圧下率で実施した。 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%.
作製したアルミニウム回路層（12）用の薄板は２８ｍｍ×２８ｍｍに切断したものを放熱装置（2）の仮組みに使用した。 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).
［他の部材］
前記緩衝層（13）（20）およびアルミニウム回路層（12）を除く部材は各例で共通のものを用いた。
[Other parts]
The members other than the buffer layers (13) and (20) and the aluminum circuit layer (12) were the same in each example.
前記絶縁基板（11）は窒化アルミニウムからなる３０ｍｍ×３０ｍｍ×厚さ０．６ｍｍの平板である。前記ヒートシンク（16）はＡｌ−１質量％Ｍｎ合金からなる扁平多穴チューブである。前記ろう材箔（14）（15）（17）は厚さ３０μｍのＡｌ−１０質量％Ｓｉ−１質量％Ｍｇ合金箔である。 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.
［ろう付］
実施例１〜３および比較例１、２の仮組物を７×１０−４Ｐａの真空中で６００℃×２０分で真空ろう付した。
[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.
［評価］
ろう付した放熱装置（2）について、実施例１、２、比較例１、２の緩衝層（13）、実施例３の緩衝層（20）の微細結晶層（22）の結晶粒の平均粒径、引張強さ、金属間化合物の平均粒径を調べた。また、断面観察により、絶縁基板（11）と緩衝層（12）（20）との接合界面における余剰ろう材（ろう材溜まり）の有無を調べた。
[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.
さらに、ろう付した放熱装置（2）に対して１２５℃と−４０℃の冷熱サイクル試験を２０００サイクル行い、冷熱サイクル試験後の絶縁基板（11）と緩衝層（13）（20）との接合界面近傍の疲労破断を調べ、下記の基準で評価した。 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.
◎：破断がほとんど見られず極めて良好である
○：僅かに破断が見られるが良好である
×：破断が激しい
これらの評価結果を表１に示す。
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.
表１に示したように、緩衝層の絶縁基板側の面の材料として結晶粒の平均粒径および引張強さを所定範囲に制御することによって、絶縁基板との接合界面における余剰ろう材を無くし、かつ熱ひずみを十分に解消できることを確認した。 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.
本発明の電子素子搭載基板は、絶縁基板の一方の面にアルミニウム回路層がろう付され、他方の面に緩衝層を介してヒートシンクがろう付された放熱装置の製造に好適に利用できる。 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…電子素子搭載用基板
2…放熱装置
11…絶縁基板
12…アルミニウム回路層
13…緩衝層（アルミニウム層、無垢材）
14、15、17…ろう材箔
18…電子素子
16…ヒートシンク
20…緩衝層（アルミニウム層、積層材）
21…母材
22…微細結晶層（絶縁基板側の層）
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)
前記アルミニウム層の少なくとも絶縁基板側の層が、ろう付後の結晶粒の平均粒径が１０〜５００μｍとなされ、かつ引張強さが１３０Ｎ／ｍｍ２以下となされたアルミニウムまたはアルミニウム合金で構成されていることを特徴とする電子素子搭載用基板。 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:
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.
材料塊に対して複数パスの圧延を行う間に、３３０〜４５０℃で１〜８時間の中間焼鈍を行い、仕上げ圧延の圧下率を１５〜４０％とすることを特徴とするアルミニウム層用材料の製造方法。 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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