JP2008025004A - Clad material and its manufacturing method, and printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clad material having low thermal expansion coefficient and excellent rolling workability. <P>SOLUTION: In a clad material (10) consisting of a core material and a cladding material on both sides of the core material, the core material (11) is composed of an aluminum alloy composed of, by mass, 11 to 20% Si, 1 to 6% Ni and the balance Al with impurities, and the cladding material (12) is composed of aluminum or aluminum alloy having ductility higher than that of the core material. It is preferable that the cladding material (12) is composed of: aluminum or aluminum alloy having a composition consisting of ≥98 mass% Al and the balance impurities; or an Al-Mg-Si alloy. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a clad material, in particular, a clad material excellent in rolling processability, a manufacturing method thereof, and a printed wiring board using the clad material for a substrate.

  In future automobiles, to reduce the environmental impact of the environment, electronic products with power steering motor-assisted electronics that contribute to energy conservation, such as sensors that control the safety of people and cars, and electronics in many ways to pursue the convenience of passengers It is predicted that there will be more and more progress.

  As automobiles become more electronic, control printed wiring boards will be used more and more. In addition, when the number of printed wiring boards increases, it is considered to place them in the engine room so as not to disturb the living space. A printed wiring board using an aluminum substrate that is more resistant to heat than a conventional glass epoxy substrate is considered suitable for placement in the engine room.

  As shown in FIG. 1, the printed wiring board (1) has an insulating layer (3) laminated on an aluminum substrate (2), and a conductive layer (4) laminated on the insulating layer (3) in a required circuit shape. The electronic component (5) is joined to the conductive layer (4) with solder (6). In general, in such a printed wiring board (1), JIS 1000 series pure aluminum having excellent thermal conductivity is used as the material of the board (2), and copper foil is used as the conductive layer (4).

However, as shown in Table 1 below, the thermal expansion coefficient of the copper foil (4) is about 17 × 10 ⁻⁶ / K, and the thermal expansion coefficient of the aluminum substrate (2) is about 24 × 10 ⁻⁶ / K. There is a difference in thermal expansion coefficient between the two. For this reason, the heat generated from the electronic component (5) that is mounted on the board, and the ambient temperature when installed in the engine room, combine with the low temperature before starting, the high temperature during use, and the low temperature during hibernation from the high temperature state. When the temperature change to the state is repeated, the electronic component (6) and the solder (6) are repeatedly subjected to a cooling / heating cycle, and fatigue cracks are generated. This is because warpage in the opposite direction due to the difference in thermal expansion coefficient between the aluminum substrate (2) and the copper foil as the conductive layer (4) repeatedly occurs. In addition, the thermal expansion coefficient of the electronic component (5) is 2 × 10 ⁻⁶ to 8 × 10 ⁻⁶ / K, and there is a difference between the copper foil (4) and the aluminum substrate (2). When (1) repeated warping, there was a problem that cracks were generated in the solder (6) due to the stress.

  If the base plate of the printed wiring board (1) is made of the same copper as the material of the conductive layer (4), the solder crack problem can be solved. However, copper has a specific gravity approximately three times that of aluminum and is not heavy because it is heavy, expensive, and easily corroded.

  In addition, low-elasticity products of insulating adhesive resins are currently used as a countermeasure against solder cracks caused by a thermal cycle. However, in the related industry of printed wiring boards, an aluminum substrate that is lighter and cheaper than copper is desired so that the selection range of many proven insulating adhesive resins can be expanded.

  In order to solve the above-mentioned problems, it has been proposed to use a rolled plate made of an Al—Si alloy having a lower thermal expansion coefficient than JIS 1000 series aluminum as the aluminum substrate (2) (Patent Document 1). , 2, 3).

  In addition, as another method for producing a low thermal expansion member, a sintered material in which ceramics such as Al and SiC and AlN are mixed, Al-SiC alloy powder is filled in a mold, and Al molten metal or Si-containing Al molten metal is used. A casting method for high-pressure injection has been proposed (see Patent Document 4).

Furthermore, an Al—Si—Ni alloy is known as a low thermal expansion aluminum alloy (Patent Document 5).
JP-A-6-41667 JP-A-2-61025 JP 2001-335872 A JP 2004-128451 A JP-A-2-73937

  However, for the rolled plates described in Patent Documents 1, 2, and 3, the rolling processability of the Al-Si alloy is poor, so that when it is rolled into a thin plate, it is cracked at the edge, and the substrate is produced in a size required for a copper-clad substrate. It was difficult. In the method combining powder metallurgy and casting described in Patent Document 4, it is difficult to manufacture a thin plate having a size required for the substrate, and the productivity is poor and the cost is high. Also, it is very hard and difficult to cut, so it is not suitable for printed wiring boards.

  In addition, the aluminum substrate (2) of the printed wiring board (1) is generally subjected to anodizing treatment in order to improve adhesion with the resin constituting the insulating layer (3), and a good surface treatment. However, good surface treatment is difficult with the methods of References 1-4. Furthermore, it is required that the surface of the aluminum substrate (2) is not easily damaged. This is because if the surface is scratched and irregularities are formed, a portion where the thickness of the insulating layer (4) becomes thin is generated and the electrical insulation reliability is impaired. Further, if there is a scratch on the surface without the insulating layer (4), the appearance quality is deteriorated and the product value is lowered.

  In addition, the Al—Si—Ni alloy also has poor rolling processability, and it is difficult to produce a thin plate suitable for a printed wiring board. In Patent Document 5, an Al—Si—Ni alloy is used as a heat roll material for a copying machine, and after extrusion, it is processed to a desired thickness through drawing and surface cutting. However, this method has poor productivity. It is not suitable for the production of printed wiring boards.

  In view of the technical background described above, the present invention is suitable for a printed wiring board, and has a low thermal expansion coefficient and an excellent rolling processability, a manufacturing method thereof, and a printed wiring board using the cladding material. And

  That is, the clad material of the present invention has the configuration described in [1] to [15] below.

[1] In a clad material composed of a core material and a skin material on both sides thereof,
The core material contains Si: 11-20% by mass and Ni: 1-6% by mass, and is composed of an aluminum alloy composed of the balance Al and impurities,
The clad material, wherein the skin material is made of aluminum or aluminum alloy having higher ductility than the core material.

  [2] The clad material according to item 1 above, wherein the skin material is made of aluminum or aluminum alloy containing Al: 98% by mass or more and the balance being impurities.

  [3] The Si concentration in the aluminum or aluminum alloy constituting the skin material is 1 mass% or less, the Fe concentration is 1 mass% or less, the Cu concentration is 0.5 mass% or less, and the Mn concentration is 2 mass% or less. 3. The clad material according to item 2 above.

  [4] The clad material according to 3 above, wherein the Mn concentration is 0.002 to 1.2 mass%.

  [5] The cladding according to item 3 above, wherein the Zn or aluminum alloy constituting the skin material has a Zn concentration of 0.5% by mass or less and a total of elements other than Al and Zn is 0.3% by mass or less. Wood.

  [6] The skin material contains Si: 0.2 to 0.8 mass%, Mg: 0.3 to 1 mass%, Fe: 0.5 mass% or less, and Cu: 0.5 mass% or less. The cladding material according to item 1, further comprising at least one of Ti: 0.5% by mass or less and B: 0.1% by mass or less, and comprising an aluminum alloy composed of the balance Al and impurities.

  [7] The clad material according to 6 above, wherein the Si concentration in the aluminum alloy constituting the skin material is 0.32 to 0.6 mass%.

  [8] The clad material according to 6 or 7 above, wherein the Mg concentration in the aluminum alloy constituting the skin material is 0.35 to 0.55 mass%.

  [9] The clad material according to any one of items 6 to 8, wherein an Fe concentration in the aluminum alloy constituting the skin material is 0.1 to 0.35 mass%.

  [10] The clad material according to any one of items 6 to 9, wherein a Cu concentration in the aluminum alloy constituting the skin material is 0.2% by mass or less.

  [11] The clad material according to any one of items 6 to 10, wherein a Ti concentration in an aluminum alloy constituting the skin material is 0.005 to 0.05% by mass.

  [12] The cladding material according to any one of items 6 to 11, wherein a B concentration in the aluminum alloy constituting the skin material is 0.06% by mass or less.

  [13] The cladding material according to any one of items 6 to 12, wherein the Mn concentration in the aluminum alloy constituting the skin material is 0.04% by mass or less and the Cr concentration is 0.03% by mass or less.

  [14] The cladding material according to any one of items 1 to 13, wherein a cladding ratio of the skin material is 0.5 to 30% per side.

  [15] The clad material according to any one of items 1 to 14, wherein the clad material has a thickness of 0.1 to 5 mm.

  The manufacturing method of the clad material of this invention has the structure as described in the following [16]-[18].

  [16] Si: 11-20% by mass and Ni: 1-6% by mass, both sides of the core material base plate made of an aluminum alloy composed of the remaining Al and impurities are more ductile than the aluminum alloy A method for producing a clad material, comprising: laminating a base material for a skin material made of aluminum or an aluminum alloy, and rolling and press-bonding them.

  [17] The method for producing a clad material according to 16 above, wherein the base material for skin material contains Al: 98% by mass or more, and the balance is made of aluminum or an aluminum alloy made of impurities.

  [18] The base material for skin material is Si: 0.2 to 0.8 mass%, Mg: 0.3 to 1 mass%, Fe: 0.5 mass% or less, and Cu: 0.5 mass% or less. The cladding material according to item 16 above, further comprising at least one of Ti: 0.5% by mass or less and B: 0.1% by mass or less, and comprising an aluminum alloy composed of the balance Al and impurities. Production method.

  The printed wiring board of the present invention has the configuration described in [19] to [21] below.

  [19] A printed wiring board characterized in that the clad material described in any one of 1 to 15 above is an aluminum substrate, an insulating layer is provided on the aluminum substrate, and copper is provided on the insulating layer. .

  [20] The printed wiring board according to [19], wherein the insulating layer includes an insulating resin or an insulating resin composition in which a thermally conductive filler is blended with the insulating resin.

  [21] The printed wiring board as described in 19 or 20 above, which has an anodized film on the surface of the aluminum substrate.

  Since the clad material according to the invention of [1] is obtained by clad a highly ductile skin material on both sides of the core material, the workability is good, and a low thermal expansion coefficient as the clad material is ensured by the core material while being thin. Can be rolled. In addition, a good surface treatment property can be obtained by the skin material.

  According to the invention [2], good processability and surface treatment can be obtained.

  According to the invention of [3], good workability of the clad material is further ensured.

  According to the invention of [4], an excellent surface treatment property of the clad material can be obtained.

  According to the invention of [5], the workability of the clad material is further ensured.

  According to the invention of [6], high surface hardness can be obtained in addition to good processability and surface treatment.

  According to the inventions [7] to [10], good workability of the clad material is further ensured.

  According to the inventions [11] and [12], castability is particularly good, and good workability is further ensured.

  According to the invention [13], particularly excellent thermal conductivity can be obtained.

  According to the invention of [14], good processability and low thermal expansion coefficient of the clad material are further ensured.

  The clad material according to the invention of [15] is suitable as a member material that causes a problem due to thermal expansion of an aluminum substrate or the like of a printed wiring board.

  According to the method for producing a clad material according to the invention of [16], the clad material according to the above [1] to [15] can be produced.

  According to the method for producing a clad material according to the invention of [17], the clad material according to the above [2] to [5] can be produced.

  According to the method for producing a clad material according to the invention of [18], the clad material according to the above [6] to [13] can be produced.

  Since the printed wiring board according to the invention of [19] uses the clad material described in any of the above [1] to [15] as an aluminum board, thermal expansion between the aluminum board and the conductive layer There is little difference in coefficients, and even when heating and cooling are repeated, there is little warping. As a result, the generation of cracks in the solder for mounting the electronic components is suppressed.

  According to the invention [20], the bondability between the insulating layer and the aluminum substrate and the bondability between the insulating layer and the conductive layer are good.

  According to the invention [21], the adhesion between the aluminum substrate and the insulating layer is good.

  FIG. 2 shows a cross-sectional view of the clad material (10) of the present invention.

The clad material (10) has good rolling workability as a clad material by clad a highly ductile skin material (12) on both sides of a core material (11) that is low in thermal expansion but difficult to roll by itself. Thus, it has both a low thermal expansion coefficient and good rolling workability. Moreover, since the Al-Si-Ni alloy used as the core material (11) has an equivalent thermal expansion coefficient at a lower concentration of Si than the Al-Si alloy, it is more than an Al-Si alloy having an equivalent thermal expansion coefficient. Rollability is improved. Hereinafter, the core material and the skin material will be described in detail.
[Heart]
The aluminum alloy used for the core material (11) is an aluminum alloy containing Si: 11 to 20% by mass and Ni: 1 to 6% by mass, the balance being Al and impurities. The reasons for limiting the content and concentration of Si and Ni are as follows.

  Si is an element necessary for reducing the thermal expansion coefficient of an aluminum alloy. The higher the Si concentration, the lower the thermal expansion coefficient. In the present invention, an aluminum alloy having an Si concentration of 11 to 20% by mass is used. If it is less than 11% by mass, the expected low coefficient of thermal expansion cannot be obtained, and if it exceeds 20% by mass, the coefficient of thermal expansion is further reduced, but rolling is performed even if the ductility is reduced and the skin material (12) is clad. And post-processing such as cutting and drilling becomes difficult. Further, since the thermal conductivity decreases as the Si concentration increases, it is not suitable for applications that require heat dissipation such as a printed wiring board. Considering both the thermal expansion coefficient and the rolling processability, the more preferable Si concentration is 18 to 20% by mass.

Ni is an element that forms an intermetallic compound of Al ₃ Ni and lowers the thermal expansion coefficient of the aluminum alloy. Although primary crystal Si has a relatively large effect on rolling workability in aluminum alloys, the addition of Ni forms an intermetallic compound of Al ₃ Ni and low thermal expansion even if the Si concentration is set in the above range. While ensuring the coefficient, the rolling workability is prevented from being lowered to facilitate the rolling of the clad material. Compared with the thermal expansion coefficient of the Al—Si alloy shown in Table 1, the same thermal expansion coefficient can be ensured with a low concentration of Si by the addition of Ni. In addition, workability such as drilling can be ensured. When the Ni concentration is less than 1% by mass, the effect of lowering the thermal expansion coefficient is poor, and when the Ni concentration exceeds 6% by mass, the melting point of the alloy becomes high and the melting temperature during casting must be increased. Therefore, in the present invention, the Ni concentration is 1 to 6% by mass. The Ni concentration is preferably in the vicinity of 5% by mass where the melting point is relatively low in the vicinity of the ternary eutectic point of Al—Si—Ni, and the more preferable Ni concentration is 4 to 6% by mass.

  The balance composition of the aluminum alloy is Al and impurities. Impurities are elements other than Si, Ni and Al, elements added for the purpose of improving the characteristics of the alloy, elements allowed to be contained within a range that does not impair the characteristics of the alloy, and contained inevitably in production. It contains an element.

As shown in Table 1, the thermal expansion coefficient of the aluminum alloy having the above composition is about 17 × 10 ⁻⁶ / K to about 20 × 10 ⁻⁶ / K, but the thermal expansion coefficient of copper is 17.0 ×. 10 ⁻⁶ / K, and when the aluminum alloy plate manufactured in the present invention is used as the substrate of the printed wiring board (1), the difference in coefficient of thermal expansion with the copper foil (4) is made as much as possible. It is possible to reduce the size, and the occurrence of cracks can be reduced. Further, as shown in Table 1, the aluminum alloy has high thermal conductivity and excellent heat dissipation.

[Skin]
On the other hand, the skin material (12) has higher ductility than the core material, and prevents or reduces ear cracks during clad rolling to ensure ductility as a clad material. A skin of composition can be recommended.

[Skin made of pure aluminum]
As one skin material, aluminum or an aluminum alloy (hereinafter abbreviated as “pure aluminum”) having an Al concentration of 98% by mass or more can be used. If the Al concentration is less than 98% by mass, the ductility is insufficient and ear cracks are likely to occur during clad rolling. The preferable Al concentration of the skin material is 99% by mass or more. Further, if the Al concentration is 98% by mass or more, the surface treatment is superior to the Al—Si alloy, so that the surface treatment is improved over the core material (11) by cladding the skin material (12). .

  Si, Fe, Cu, and Mn can be listed as elements that may impair the ductility of the skin material (12), and the Si concentration is 1 mass% or less, the Fe concentration is 1 mass% or less, and the Cu concentration is 0, respectively. It is preferable that it is 0.5 mass% or less and Mn concentration is 2 mass% or less. A particularly preferable Si concentration is 0.6% by mass or less, a particularly preferable Fe concentration is 0.7% by mass or less, a particularly preferable Cu concentration is 0.2% by mass or less, and a particularly preferable Mn concentration is 1.2% by mass or less.

  Furthermore, Zn can be listed as an element that may hinder the ductility of the skin material, and the Zn concentration is preferably 0.5% by mass or less. Further, impurity elements other than Al and Zn, such as Cr and Ti, are preferably 0.3% by mass or less in total. A particularly preferable Zn concentration is 0.1% by mass or less, and a particularly preferable total of elements other than Al and Zn is 0.15% by mass or less.

  Among the above elements, even when Mn is contained in a relatively large amount, scratch resistance after rolling (hardness to scratch) without sacrificing surface treatment properties such as anodizing treatment or chemical conversion treatment of the clad material. There is an effect of improving. In order to ensure ductility, it is preferable that the amount of Mn is small. However, the above effect can be imparted even in a range that does not inhibit clad rolling, specifically in a range where the Mn concentration is 0.002 to 1.2% by mass. . Considering only the ductility of the skin material, the Mn concentration is preferably 0.05% by mass or less, and when priority is given to improving the scratch resistance of the surface, 0.3 to 1.2% by mass is preferable.

[Skin made of Al-Mg-Si alloy]
As another skin material, an aluminum alloy containing a predetermined amount of Si, Mg, Fe, Cu, Ti, and B (hereinafter abbreviated as “Al—Mg—Si alloy”) can be used. In addition to high ductility, the Al-Mg-Si-based alloy is superior in surface treatment and hardness to the core material (11), so that the surface treatment and scratch resistance can be obtained by cladding the skin material (12). Is improved.

  In the Al—Mg—Si based alloy, the reason for limiting the content and concentration of the above elements is as follows.

  Si and Ti are elements necessary for improving the hardness. If the Si concentration is less than 0.2% by mass or the Mg concentration is less than 0.3% by mass, sufficient hardness cannot be obtained. On the other hand, when the Si concentration exceeds 0.8 mass% and the Mg concentration exceeds 1 mass%, the rolling load of hot rolling becomes high, and the effect of preventing ear cracks becomes poor as a cladding material of the clad material. A more preferable Si concentration is 0.32 to 0.6% by mass, and a more preferable Mg concentration is 0.35 to 0.55% by mass.

  Fe and Cu are effective elements from the viewpoint of moldability, but if they are contained in a large amount, the corrosion resistance is lowered and the practicality as an alloy plate becomes poor. For this reason, each of the Fe concentration and the Cu concentration is set to 0.5 mass% or less. A preferable Fe concentration is 0.1 to 0.35% by mass, and a preferable Cu concentration is 0.2% by mass or less. Moreover, the preferable lower limit of Cu concentration is 0.001 mass%.

  Ti and B have an effect of miniaturizing crystal grains and preventing solidification cracking when an aluminum alloy is cast into a slab. The effect is obtained by adding at least one of Ti or B, and both may be added. However, if it is contained in a large amount, the amount of the crystallized product increases and a large crystallized product is formed, so that the rolling processability of the product is lowered. In addition, thermal conductivity and conductivity are reduced. For these reasons, the Ti concentration is 0.5% by mass or less. A preferable Ti concentration is 0.005 to 0.05 mass%. The B concentration is 0.1% by mass or less. A preferable B concentration is 0.06% by mass or less. Moreover, the preferable lower limit of B concentration is 0.001 mass%.

  In addition, various impurity elements are unavoidably contained in the aluminum alloy ingot, but Mn and Cr are preferably as small as possible because they cause a decrease in thermal conductivity and conductivity. It is preferable to regulate the Mn concentration as an impurity to 0.1% by mass or less and the Cr concentration to 0.1% by mass or less. A particularly preferable Mn concentration is 0.05% by mass or less, and a particularly preferable Cr concentration is 0.03% by mass or less. Moreover, it is preferable that other impurity elements are 0.05 mass% or less as each density | concentration.

[Clad material]
In the clad material of the present invention, the clad rate of the skin material is represented by clad rate (%) = (thickness of skin material / clad material) × 100. Although the said cladding rate is not limited, It is preferable to set it as 0.5 to 30% about one side. If the clad rate is less than 0.5%, the rolling processability as a clad material is insufficient, and the effect of preventing the ear cracks during clad rolling is poor. On the other hand, if the clad rate is 30% or less, the rolling processability can be sufficiently improved, so that the merit of setting the clad rate exceeding 30% is poor. Further, since the skin material has a larger thermal expansion coefficient than the core material, if the cladding ratio exceeds 30%, the thermal expansion coefficient as the cladding material also increases. A particularly preferable cladding ratio is 5 to 10% per side.

  Moreover, although the thickness of a clad material is not limited, since the rolling workability is improved by clad the skin material, it can be processed into a thin plate of 0.1 to 5 mm. The thin plate having the above thickness can be suitably used as an aluminum substrate of a printed wiring board, and particularly preferable thickness is 0.5 to 4 mm for use as a substrate.

  Since the clad material of the present invention has a low thermal expansion property, it can reduce solder cracks, and its use is not limited as a base for a printed wiring board, but it is particularly suitable as a base for an in-vehicle printed wiring board that is repeatedly subjected to a thermal cycle. . As other applications, it is also suitable as a substrate for in-vehicle use, LED use, PDP driver use, liquid crystal driver use, and various power transistors. Further, it can be widely used for various applications such as a case or a structural member such as a chassis for mounting various electronic components that generate heat, and other parts and members for alleviating problems caused by thermal expansion.

  In addition, since the surface treatment is enhanced by the skin material as compared with the core material, the adhesion with the anodized film and the chemical film is superior to that of the conventional product. For this reason, in the said use, surface treatment can be given as needed.

  In particular, when an Al—Mg—Si alloy is used as the skin material, the surface hardness is high depending on the composition, in other words, the surface hardness of the clad material is high. Due to the high surface hardness of the clad material, it is difficult to be damaged during handling and processing. For this reason, the appearance quality is good. In addition, when there are few surface irregularities due to scratches on the surface on which the insulating layer is to be formed, an insulating layer having a uniform thickness can be formed, and thus a highly reliable insulating layer having excellent dielectric strength can be formed. Moreover, although it becomes easy to produce a dielectric breakdown in the edge part of a damage | wound, it can prevent by making a clad material hard to get damaged. Further, even when pure aluminum added with Mn is used as the skin material, the scratch resistance is improved.

  Further, the composition and clad rate of the skin material on both sides may be the same or different, but it is easy to make the composition and clad rate the same on both sides.

[Clad material manufacturing method]
The manufacturing method of the clad material of the present invention is not limited, and can be manufactured by a method similar to a known clad material as an example. For example, a core material base plate and a skin material base plate having a predetermined composition are manufactured by an arbitrary method such as casting, rolling, and extrusion, and these are overlapped and clad rolled and pressure bonded, and if necessary, further to a required thickness. Roll. The rolling conditions are not limited in any way, and rolling workability is ensured as a clad material by the skin material, so that it can be rolled into a thin plate even by cold rolling. Moreover, since the production is performed by rolling, it is possible to produce a clad material having a large size. In addition, the core material and the skin material are pressure-bonded by clad extrusion, or a sheet-like skin material separately manufactured while casting the core material by clad casting is fused, and if necessary, further rolled to the required thickness. Can also be manufactured.

[Printed wiring board]
As shown in FIG. 1, the printed wiring board of the present invention uses the clad material of the present invention described above as a substrate (10), and an insulating layer (3) is laminated on the aluminum substrate (10). A copper foil is laminated on the insulating layer (3) as a current-carrying layer (4) having a required circuit shape. In the printed wiring board (1), since the thermal expansion coefficient of the aluminum substrate (10) is low, the difference in thermal expansion coefficient from the conductive layer (4) is small. For this reason, even if heating and cooling are repeated by heat generated from the electronic component (5) mounted on the energization layer (4), there is little warpage and the occurrence of cracks in the solder (6) is suppressed.

  The insulating layer (3) is made of an insulating material bonded directly or indirectly to the clad material (10). The insulating material is not particularly limited as long as it has insulating properties, but an insulating resin or an insulating resin composition in which a thermally conductive filler is blended with the insulating resin can be recommended. These resin-based insulating layers have good bondability with the aluminum substrate and the current-carrying layer, and are less likely to break than ceramics, and can produce a large-area substrate. In the present invention, the insulating layer (3) is not limited to the insulating resin or the insulating resin composition, and ceramic can also be used. In the case of ceramic, it is bonded to the clad material (10) with an adhesive, for example.

  The insulating resin is not limited, but is preferably a resin having excellent heat resistance, a low coefficient of thermal expansion, and being in close contact with the clad material (10) and excellent adhesion. An epoxy resin or a polyimide resin can be recommended as a resin that satisfies these conditions. Furthermore, epoxy resin can be recommended because it has particularly good adhesion to copper foil, low hygroscopicity, and is inexpensive. Polyimide resin is recommended because it has excellent chemical resistance and has a small coefficient of thermal expansion in the thickness direction, and deformation is suppressed.

Further, by using an insulating resin composition in which a heat conductive filler is blended with the insulating resin, the heat conductivity of the insulating layer can be increased, and the heat dissipation performance can be improved. The thermally conductive filler is preferably an insulator and has a high thermal conductivity, and examples thereof include metal oxides or metal nitrides. Specifically, SiO ₂ , Al ₂ O ₃ , BeO, MgO , Si ₃ N ₄ , BN, and AlN. These heat conductive fillers may be used alone or in combination of any plural kinds. The heat conductive filler has a higher thermal conductivity of the insulating layer (3) as the concentration in the resin composition is higher, and is preferably 40 to 90% by volume. If it is less than 40% by volume, the effect of improving the thermal conductivity is poor, and if it exceeds 90% by volume, the adhesion with the clad material (10) is lowered and the heat dissipation performance is lowered. A particularly preferred concentration is 60 to 80% by volume. Moreover, the particle size of a heat conductive filler should just be smaller than the thickness of an insulating layer, and 10-40 micrometers is preferable.

  The thickness of the insulating layer (3) is preferably 0.01 to 0.5 mm in any of the above two types.

  The joining of the clad material (10), the insulating layer (3), and the energization layer (4) is appropriately performed by a known method such as hot pressing.

  For example, to explain an example of hot pressing using a thermosetting resin as the insulating resin of the insulating layer (3), the conductive layer (4), the insulating layer (3), and the cladding material (10) are overlapped, and It is sandwiched between stainless steel plates, further pressed through a cushion material, and heated. By this hot pressing, the insulating layer (3) is cured and bonded to the clad material (10) and the energizing layer (4), and these are integrated. Further, when the energization layer (4) is bonded to a part of the insulating layer (3), the bonding may be performed using an alignment sheet and a backing plate. That is, the current-carrying layer (4) is attached to the alignment sheet, and is placed on the insulating layer (3) through a contact plate having a hole in a position corresponding to the current-carrying layer (4) and overlapped with the clad material (10). . These may be sandwiched between stainless steel plates and further heated by pressing through a cushioning material. As a result, the energization layer (4) is bonded to a predetermined position of the insulating layer (3). Copper used for the energization layer may be pure copper or a copper alloy, and is not limited by the manufacturing method or shape such as a copper plate, copper foil, copper plating layer, or the like.

  It is also preferable to form an anodized film on the surface of the clad material (10) in order to improve the adhesion between the clad material (10) and the insulating layer (3). An insulating resin enters the pores of the anodized film, and a high adhesive force due to the anchor effect can be obtained. The kind of film is not limited, and as an example, a film made of phosphoric acid, a film made of sulfuric acid, or the like can be used as appropriate. The clad material of the present invention is excellent in adhesion to the anodized film because the surface treatment is enhanced by the skin material.

  Nine types of Al-Si-Ni alloys A to I shown in Table 1 are used as the core material, and four types of pure aluminum (a4 is a comparative composition) shown in Table 2 and Table 3 as the skin material. The clad materials shown in Tables 4 to 7 were manufactured using four types of Al-Mg-Si based alloys b1 to b4 (b4 is a comparative composition).

  For the core material, an ingot is produced by the book mold method, and a plate having a thickness of 15 mm is obtained by double-side chamfering from the ingot that has been heated and held at 490 ± 10 ° C. for 10 hours and then air-cooled. Used as a base plate. As the skin material, a base material for a skin material was obtained by rolling an ingot. The thickness of the base plate for skin material is 2 mm (cladding rate 10.5%), 1.5 mm (cladding rate 8.3%), 0.5 mm (cladding rate 3.1%) in order to change the cladding rate. ).

  And in all the Examples of Tables 4 and 6, Comparative Examples Nos. 41 to 49 in Table 5, and Comparative Examples Nos. 101 to 109 in Table 7, skin material base plates are provided on both surfaces of the core material base plate. It was repeatedly heated at 500 ° C. for 2 hours, and rolled at a reduction ratio of about 2 to 10% up to a sheet thickness of 9 mm, and further clad rolled at a reduction ratio of 10 to 20% up to a sheet thickness of 3 mm. Further, the clad material (10) as shown in FIG. 2 was produced by cold rolling to a thickness of 1 mm. Tables 4 to 7 show the alloy symbols of the core material and the skin material, and the cladding ratio on one side.

  Further, in Comparative Examples Nos. 50 to 57 in Table 5, the core material was rolled alone to a thickness of 1 mm.

  The thermal expansion coefficient and thermal conductivity of each clad material were measured and compared with the case of the core material alone. In addition, the thermal expansion coefficient and thermal conductivity of the core material alone in Tables 4 to 7 are quoted from Table 1.

  The rolling processability, surface treatment property and surface hardness of each clad material were tested and evaluated by the following methods. An evaluation result is combined with Tables 4-7, and is shown.

(Rolling workability)
The clad rolling was evaluated according to the following criteria based on the length of the ear crack (the length of the ear crack from the side edge) generated at the side edge in the width direction of the clad material.
○: Less than 4 mm △: 4 mm or more and less than 6 mm △: 6 mm or more and less than 9 mm Δ △: 9 mm or more and less than 12 mm Δ ×: 12 mm or more and less than 15 mm × Δ: 15 mm or more and less than 20 mm ×: 20 mm or more

(Surface treatment-Anodizing treatment)
The clad material was anodized at a current density of 1.5 A / dm ² in a sulfuric acid bath at 20 ° C. and 15 V / V% to form a film having a thickness of 1 μm. The formed anodized film was magnified 100 times with an optical microscope, and the number of pits in a 10 mm square field of view was counted. It can be evaluated that the smaller the number of pits, the better the surface treatment.
◎: 3 or less ○: 4 to 10 ×: 11 or more

(surface hardness)
Brinell hardness (H _B ) was measured.

From the results of Tables 4 to 7, the clad material of each example has better rolling processability than the core material alone, and can produce a thin plate. In addition, the thermal expansion coefficient and thermal conductivity of the core material are substantially maintained, and the aluminum plate has low thermal expansion and high thermal conductivity. The thermal expansion coefficient of the clad material is about 17 × 10 ⁻⁶ / ° C. to about 20 × 10 ⁻⁶ / ° C., and these thermal expansion coefficients are lower than 24 × 10 ⁻⁶ / ° C. of pure Al. Close to thermal expansion coefficient. Moreover, compared with Comparative Example No. 50-57, surface treatment property improved rather than the core material alone by cladding the skin material, and the adhesion of the resin insulating layer was enhanced by forming the anodized film, and the electrical insulating property was improved. Reliability can be improved. By cladding the skin material defined in the present invention and forming an anodic oxide film with higher adhesion, a good withstand voltage can be realized. Furthermore, a clad material using pure aluminum or Al—Mg—Si alloy with Mn added to the skin material has high surface hardness and is hardly scratched.

  On the other hand, in Comparative Examples Nos. 49 and 109, since the amount of Si in the core material was excessive, rolling workability was still insufficient even when the skin material was clad. Further, as shown in Comparative Examples Nos. 50 to 57, with the core material alone, an ear crack occurred during rolling into a thin plate. In addition, as shown in Comparative Examples Nos. 41 to 48 and 101 to 108, when a skin material that deviates from the composition in the present invention is used, rolling workability as a clad material is insufficient, and a good clad material is manufactured. I couldn't.

  The clad material of the present invention can be manufactured as a thin plate because of its low thermal expansion and good rolling workability, and can be widely used as a member material that causes problems due to thermal expansion of an aluminum substrate of a printed wiring board.

It is sectional drawing of a printed wiring board. It is sectional drawing of the clad material concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Printed wiring board 2 ... Aluminum substrate 3 ... Insulating layer 4 ... Current carrying layer (copper foil)
10 ... Clad material
11 ... Heartwood
12… Skin

Claims (21)

In the cladding material consisting of the core material and the skin material on both sides,
The core material contains Si: 11-20% by mass and Ni: 1-6% by mass, and is composed of an aluminum alloy composed of the balance Al and impurities,
The clad material, wherein the skin material is made of aluminum or aluminum alloy having higher ductility than the core material.   The clad material according to claim 1, wherein the skin material is made of aluminum or an aluminum alloy containing Al: 98% by mass or more, and the balance being impurities.   3. The Si or aluminum alloy constituting the skin material has an Si concentration of 1% by mass or less, an Fe concentration of 1% by mass or less, a Cu concentration of 0.5% by mass or less, and an Mn concentration of 2% by mass or less. The clad material described in 1.   The clad material according to claim 3, wherein the Mn concentration is 0.002 to 1.2 mass%.   The clad material according to claim 3, wherein a Zn concentration in aluminum or aluminum alloy constituting the skin material is 0.5 mass% or less, and a total of elements other than Al and Zn is 0.3 mass% or less.   The skin material contains Si: 0.2 to 0.8 mass%, Mg: 0.3 to 1 mass%, Fe: 0.5 mass% or less, and Cu: 0.5 mass% or less, and further Ti The clad material according to claim 1, comprising at least one of: 0.5% by mass or less and B: 0.1% by mass or less, and made of an aluminum alloy composed of the balance Al and impurities.   The clad material according to claim 6 whose Si concentration in the aluminum alloy which constitutes the skin material is 0.32-0.6 mass%.   The clad material according to claim 6 or 7, wherein the Mg concentration in the aluminum alloy constituting the skin material is 0.35 to 0.55 mass%.   The clad material according to any one of claims 6 to 8, wherein an Fe concentration in the aluminum alloy constituting the skin material is 0.1 to 0.35 mass%.   The clad material according to any one of claims 6 to 9, wherein a Cu concentration in the aluminum alloy constituting the skin material is 0.2 mass% or less.   The clad material according to any one of claims 6 to 10, wherein a Ti concentration in an aluminum alloy constituting the skin material is 0.005 to 0.05 mass%.   The clad material according to any one of claims 6 to 11, wherein a B concentration in the aluminum alloy constituting the skin material is 0.06% by mass or less.   The clad material according to any one of claims 6 to 12, wherein the Mn concentration in the aluminum alloy constituting the skin material is 0.04 mass% or less and the Cr concentration is 0.03 mass% or less.   The cladding material according to any one of claims 1 to 13, wherein a cladding ratio of the skin material is 0.5 to 30% per one surface.   The clad material according to any one of claims 1 to 14, wherein a thickness of the clad material is 0.1 to 5 mm.   Aluminum or aluminum having ductility higher than that of the aluminum alloy on both sides of the core material base plate made of an aluminum alloy containing Si: 11 to 20% by mass and Ni: 1 to 6% by mass, and the balance Al and impurities. A method for producing a clad material, comprising: laminating a base material for a skin material made of an alloy and rolling and crimping the same.   The method for producing a clad material according to claim 16, wherein the base plate for skin material is made of aluminum or aluminum alloy containing Al: 98% by mass or more and the balance being impurities.   The base material for skin material contains Si: 0.2 to 0.8 mass%, Mg: 0.3 to 1 mass%, Fe: 0.5 mass% or less, and Cu: 0.5 mass% or less. The method for producing a clad material according to claim 16, further comprising at least one of Ti: 0.5% by mass or less and B: 0.1% by mass or less, and comprising an aluminum alloy composed of the balance Al and impurities. .   A printed wiring board, wherein the clad material according to claim 1 is an aluminum substrate, an insulating layer is provided on the aluminum substrate, and copper is provided on the insulating layer.   The printed wiring board according to claim 19, wherein the insulating layer includes an insulating resin or an insulating resin composition in which a thermally conductive filler is blended with the insulating resin. The printed wiring board according to claim 19 or 20, further comprising an anodized film on a surface of the aluminum substrate.

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