JP2000087293A - Base sheet for electronic apparatus made of nickel plating aluminum base composite material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a base sheet capable of obtaining good solderability, free from the excessive spread of solder and exhibiting suitable solder wettability by plating the surface of an aluminum base composite material with an Ni metallic layer or an Ni-P alloy layer to the thickness above the specified one as a substrate and plating the surface with Ni-Co, Ni-Co-B and Ni-B alloy layers to the thickness above the specified one as surface layers. SOLUTION: The surface of an aluminum base composite material is plated with an Ni metallic layer or an Ni-P alloy layer to >=3 μm thickness as a substrate, and the surface is preferably plated with one or more kinds among an Ni-Co alloy layer, an Ni-Co-B alloy layer and an Ni-B alloy layer to >=0.01 μm thickness as surface layers. Next, it is subjected to deaerating treatment of executing heating at a temp. rising rate of <=200 deg.C/hr in a reducing or nonoxidizing atmosphere or in a vacuum and executing holding at 200 to 500 deg.C for a prescribed time. The substrate increases the adhesion of the surface layers with the aluminum base composite material and improves the corrosion resistance of the aluminum base composite material, and in the surface layers, good solderability can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base plate for an electronic device made of a Ni-plated aluminum-based composite material, which exhibits good solderability and does not spread excessive solder, exhibits a proper solder wettability, and a method of manufacturing the same. About.

[0002]

2. Description of the Related Art Aluminum-based composite materials are composite materials obtained by dispersing fibrous or particulate ceramics or carbon in aluminum or an aluminum alloy, and have been used in fields requiring strength and wear resistance. Recently, however, it has been adopted as a substrate for large-capacity IGBT (Insulated Gate Bipolar Transister) modules that easily generate heat by utilizing its features of low thermal expansion and high thermal conductivity. By the way, as the substrate, a DBC substrate (Dire
ct Bonding Copper: A board with a ceramic plate coated with Cu) is soldered. However, since the aluminum-based composite material has poor solderability, Ni is plated on the soldered portion of the aluminum-based composite material to improve solderability. It has been improved (JP-A-5-86481).

[0003] However, the Ni plating layer is not exposed to the air.
If left for about a week, an oxide film harmful to soldering is formed, but this oxide film is removed by the chlorine-based flux applied at the time of soldering, and soldering is performed almost satisfactorily. By the way, in recent years, from the viewpoint of environmental protection, the use of the chlorine-based flux has tended to be refrained, and instead, a low-chlorine-based flux or a flux containing rosin as a main component has been used. A non-flux soldering method has been developed in which soldering is performed without using a furnace in a hydrogen gas atmosphere furnace, a mixed gas atmosphere furnace of nitrogen and hydrogen, or an inert gas atmosphere furnace.

[0004]

However, in the above-mentioned non-flux soldering method, since there is no deoxidizing effect as much as that of chlorine-based flux, the presence of a small amount of an oxide film deteriorates solder wettability and deteriorates solderability. There is a problem of doing. For example, after a Ni-plated aluminum-based composite material is left in the air for one week in a factory, a DBC substrate is eutectic soldered (Sn).
When soldering is performed in a reducing atmosphere (hydrogen-10 vol% nitrogen) furnace using (-37 wt% Pb), a non-joined (non-wetting) portion or a portion where a fillet (build-up portion of solder) is not formed may occur. For this reason, surface treatment methods with good solder wettability have been actively studied. On the other hand, if the solder wettability is too good, the solder spreads to the area where the solder is not needed, causing poor appearance and reduced function. Therefore, the spread of the solder is suppressed by masking with a resist (epoxy resin or the like). However, there is a problem that productivity is hindered.

[0005] From the above, the present inventors have found that the surface of an aluminum-based composite material which exhibits good solderability even in the non-flux soldering method, does not spread excessive solder, and exhibits appropriate solder wettability. Research was conducted on the treatment method, and as a result, it was found that an appropriate solder wettability can be obtained by plating a predetermined Ni alloy on the aluminum-based composite material, and further research was advanced to complete the present invention. An object of the present invention is to provide a base plate for electronic equipment made of a Ni-plated aluminum-based composite material, which exhibits good solderability and does not spread excessive solder and exhibits appropriate solder wettability, and a method for producing the same.

[0006]

According to the first aspect of the present invention,
Ni metal layer or Ni as underlayer on aluminum matrix composite
-P alloy layer is plated to a thickness of 3 μm or more, and Ni-Co alloy layer, Ni-Co-B alloy layer as a surface layer thereon,
Alternatively, a base plate for electronic equipment made of a Ni-plated aluminum-based composite material, wherein at least one of the Ni-B alloy layers is plated to a thickness of 0.01 μm or more.

According to a second aspect of the present invention, a Ni metal layer or a Ni—P alloy layer is plated as an underlayer on an aluminum-based composite material to a thickness of 3 μm or more, and a Ni—C layer is formed thereon as a surface layer.
o alloy layer, Ni—Co—B alloy layer or at least one of the Ni—B alloy layers is plated to a thickness of 0.01 μm or more, and then plated in a reducing atmosphere, a non-oxidizing atmosphere, or a vacuum. A method for producing a base plate for an electronic device made of an aluminum-based composite material, comprising performing a deaeration process of heating at a heating rate of 200 ° C. or less per hour and maintaining the temperature at 200 to 500 ° C. for a predetermined time.

[0008]

DETAILED DESCRIPTION OF THE INVENTION In the invention as set forth in claim 1, Ni metal or Ni-P plated on an aluminum-based composite material is used.
The base layer of the alloy enhances the adhesion of the surface layer to the aluminum-based composite material, and improves the corrosion resistance of the aluminum-based composite material by plating over the entire surface of the aluminum-based composite material. The surface layer is composed of at least one of a Ni-Co alloy layer, a Ni-Co-B alloy layer, and a Ni-B alloy layer. It does not spread the solder and shows appropriate solder wettability.

When the P content of the Ni—P alloy layer of the underlayer is 5 to 15 wt%, the effect of the underlayer is best exhibited. Also, a Ni—Co alloy layer of the surface layer, N
C in i-Co-B alloy layer or Ni-B alloy layer
The contents of o and B are 10 to 30 wt% and 1 to 5 wt%, respectively.
%, The effect as the surface layer is best exhibited.

In the present invention, the thickness of the underlayer is preferably 3
The reason why the thickness is specified to be not less than 3 μm is that if the thickness is less than 3 μm, the base of the aluminum-based composite material may be exposed and may not serve as a base layer. On the other hand, if the underlayer is too thick, the thermal resistance increases, the heat radiation property decreases, and the cost increases. In the present invention, the reason for defining the thickness of the surface layer to be 0.01 μm or more is as follows.
If the thickness is less than 0.01 μm, the effect cannot be sufficiently obtained. Therefore, a particularly desirable thickness is 0.02 μm or more. If the thickness of the surface layer is more than 5 μm, the effect is saturated and uneconomical, and the thickness is preferably 5 μm or less. The same effect can be obtained even if the surface layer is formed of a plurality of alloy layers. The lower layer is N
It may be formed of an i-metal layer and a Ni-P alloy layer.

In the present invention, aluminum serving as a matrix of the aluminum-based composite material includes pure Al or Al--Si
Any aluminum alloy such as an alloy or an Al—Mg alloy is used, and SiC, AlN, ZrO ₂ , Si ₃
Ceramics such as N ₄ and SiO ₂ or fibers or particles such as carbon are used, and the combination of the Al alloy and the dispersing material is optional. Since the aluminum-based composite material has excellent thermal conductivity and a small coefficient of thermal expansion, when used as an electronic device base plate, heat generated by the electronic device is radiated well. In particular, since the Al-Si alloy and the carbon fiber both have a small coefficient of thermal expansion and are close to each other, the Al-based composite material composed of the two materials is hardly peeled off between the Al matrix and the dispersing material, and the aluminum alloy is hardly peeled off. High reliability of the base composite material. In addition, since the Al-Si alloy has good flowability, a high-quality aluminum-based composite material can be obtained. Examples of the dispersant having a small coefficient of thermal expansion include SiC, A in addition to carbon fiber (particles).
Fibers (particles) such as 1N and ZrO ₂ are exemplified.

According to a second aspect of the present invention, after a base layer and a surface layer are plated on an aluminum-based composite material, a deaeration treatment is performed under a predetermined heating condition in a reducing atmosphere, a non-oxidizing atmosphere, or a vacuum ( That is, a plating solution that has penetrated into the aluminum-based composite material is removed.) This is a method for manufacturing a base plate for electronic equipment made of a Ni-plated aluminum-based composite material. Wettability is obtained. For the deaeration treatment, a hydrogen gas atmosphere furnace, a mixed gas atmosphere furnace of nitrogen and hydrogen, a non-oxidizing atmosphere furnace, a vacuum furnace, or the like is used.

In the present invention, the reason why the rate of temperature rise in the degassing treatment is set to 200 ° C. or less per hour is as follows.
If the temperature exceeds 00 ° C., the plating solution or the like that has permeated the aluminum-based composite material will rapidly evaporate and the plating layer will swell. In addition, the heating temperature in the deaeration treatment is 200 to 500 ° C.
The reason for this is that if the temperature is lower than 200 ° C., the plating solution or the like that has permeated the aluminum-based composite material is not removed, and if the temperature exceeds 500 ° C., the aluminum-based composite material is altered or melts. If the temperature taken out of the furnace exceeds 100 ° C., the surface layer may be deteriorated.
It is preferable to cool the inside of the furnace to a temperature of not more than ° C. The reason why the deaeration treatment is performed in a reducing atmosphere, a non-oxidizing atmosphere, or a vacuum is to prevent oxidation and deterioration of a surface layer such as a Ni—Co alloy layer.

The underlayer and the surface layer on the aluminum-based composite material are preferably formed by a wet plating method such as an electrolytic plating method or an electroless plating method at a simple and low cost.
It can be formed by PVD method, CVD method, etc.
In this case, degassing is not required.

[0015]

[Ni electrolytic plating]

Plating solution: NiSO ₄ 240 g / liter, NiCl ₂ 45 g / liter,
H ₃ BO ₃ 30g / l, additive A-1 (10ml / l), A-2
(1 ml / liter) (A-1, A-2 are manufactured by Uemura Kogyo Co., Ltd.). Plating conditions: 5A / dm ² , solution temperature 55 ° C, plating thickness 1
12 minutes of energization time at 0 μm. [Ni-Co alloy electrolytic plating] Plating solution: NiSO ₄ 180 g / liter, CoSO ₄ 60 g / liter,
NiCl ₂ 45 g / l, H ₃ BO ₄ 30 g / l. Plating conditions: 5 A / dm ² , solution temperature 55 ° C., plating time 0.5 μm, energization time 30 seconds. [Ni-Co-B alloy electroless plating] Plating solution: NiCl ₂ 10 g / liter, CoCl ₂ 45 g / liter,
NH ₄ Cl 12 g / liter, (C ₂ H ₅ ) ₄ NBr 45 g / liter, N
H ₃ 160 cc / liter, NaBH ₄ 1 g / liter. Plating conditions: immersion in a solution at a temperature of 40 to 45 ° C., immersion time 10 minutes when plating thickness is 0.5 μm. [Ni-B alloy electroless plating] Plating liquid: NiSO ₄ 240 g / l, NiCl ₂ 45 g / l, H ₃ BO ₄ 30g / l, trimethylamine borane 3 g / l. Plating conditions: 1 A / dm ² , solution temperature 55 ° C., plating thickness 0.5 μm, energization time 3 minutes. [Deaeration treatment] Using a 100% hydrogen gas atmosphere furnace, heating rate 50 ° C / hour, holding temperature 300 ° C, holding time 1 hour,
Furnace cooled to 80 ° C.

Comparative Example 1 An electronic device base plate made of an aluminum-based composite material was manufactured in the same manner as in Example 1 except that the thickness of the underlayer, the thickness of the surface layer, and the deaeration conditions were not specified by the present invention. Manufactured.

With respect to each of the Ni-plated aluminum-based composite materials produced in Example 1 or Comparative Example 1, the solder spread ratio and the solder wetting angle were measured to comprehensively evaluate the solderability. N
The same measurement and evaluation were performed on a conventional material in which only i was plated. In addition, the solder spread ratio was as follows. A plate solder was placed on a Ni-plated aluminum-based composite material, and this was heated in a 100% hydrogen gas atmosphere furnace at a heating rate of 40 ° C./hr and heating conditions of 300 ° C.
Heating was performed for 30 minutes, and the solder area after heating was divided by the solder area before heating. The plate solder has a thickness of 0.2 mm,
A Pb-50 wt% Sn alloy having a width of 16 mm and a length of 30 mm was used. As shown in FIG. 1, the solder wetting angle is such that molten solder flows on the surface layer 3 formed on the aluminum-based composite material 1 via the base layer 2 and passes through the center of the solidified solder 4. The average value of the angles α and β formed by the surfaces of both edges of an arbitrary longitudinal section with the surface of the Ni plating layer 2 was shown. Acceptance criteria were a solder spread ratio of 1 to 1.5 and a solder wetting angle of 30 degrees or less.
The results are shown in Tables 1 to 3.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

As is clear from Tables 1 to 3, Nos. 1 to 23 of the present invention (Example 1) all satisfy the acceptance criteria with respect to the solder spread ratio (solder wettability) and the solder wetting angle. It was excellent overall. Also, the surface layer did not peel off. In contrast, No. 1 of Comparative Example 1
24 to 28, and No. 29 of the conventional material, the spread ratio of the solder (solder wettability) and the wettability angle of the solder were lower than the acceptance criteria, and were inferior overall. In Nos. 24 and 25, peeling was partially observed in the surface layer. This is because the underlayer was thin.

Example 2 Al-12 wt% Si-1 wt%
Aluminum-based composite material (thickness 3 mm, width 90 mm, length 150 mm) in which 60 vol% of SiC fibers are dispersed in a Mg-1 wt% Cu alloy
mm) is electroless-plated with a Ni-5 wt% P alloy, and Ni-Co alloy, Ni-Co-B alloy, or Ni-
The B alloy was electroplated and finally degassed to produce an aluminum-based composite electronic device base plate. The plating thickness of the underlayer and the surface layer, and the deaeration conditions were variously changed within the range of the present invention. Except for Ni-5 wt% P alloy plating, it was manufactured in the same manner as in Example 1. The electroless plating conditions of the Ni-P alloy are shown below. [Ni-P alloy electroless plating] Plating solution: DX-M (100 ml / liter) manufactured by Uemura Kogyo Co., Ltd.
X-A (50 ml / liter). Plating conditions: immersion time 30 minutes at a liquid temperature of 90 ° C. and a plating thickness of 10 μm.

(Comparative Example 2) An aluminum-based composite electronic device base plate was manufactured in the same manner as in Example 2 except that the plating thickness of the underlayer and the surface layer and the deaeration conditions were outside the scope of the present invention. Was manufactured.

With respect to each of the Ni-plated aluminum-based composite materials produced in Example 2 or Comparative Example 2, the solder spread ratio and the solder wetting angle were measured to comprehensively evaluate the solderability. N
The same measurement and evaluation were performed on a conventional material in which only i was plated. The spread ratio of the solder was determined by placing a plate solder on a Ni-plated aluminum-based composite material, and heating it in a mixed gas furnace of 90 vol% nitrogen and 10 vol% hydrogen at a heating rate of 40 ° C / hr and heating conditions of 400 ° C x 30 ° C. And the solder area after heating and cooling was divided by the solder area before heating. The plate solder has a thickness of 0.2 mm, a width of 16 mm, and a length of 30 mm.
An -10 wt% Al alloy was used. The solder wetting angle is
The measurement and evaluation were performed in the same manner as in Example 1. Acceptance criteria were a solder spread ratio of 1 to 1.5 and a solder wetting angle of 30 degrees or less. The results are shown in Tables 4 to 6.

[0025]

[Table 4]

[0026]

[Table 5]

[0027]

[Table 6]

As is clear from Tables 4 to 6, in Nos. 41 to 63 of the present invention (Example 2), no swelling of the plating layer was recognized, and the solder spread was satisfied. And had excellent solderability. Also, the surface layer did not peel off. On the other hand, Nos. 64 to
Both No. 68 and No. 69 of the conventional material were below the acceptance criteria, and the solderability was totally poor. In Nos. 64 and 65, peeling was partially observed in the surface layer. This is because the underlayer was thin.

[0029]

As described above, the base plate for an electronic device made of an aluminum-based composite material according to the present invention has an N-based composite material on an aluminum-based composite material.
The i-layer is plated with an appropriate thickness, and Ni-C
Since the surface layer of the o-alloy layer, the Ni-Co-B alloy layer or the Ni-B alloy layer is plated to an appropriate thickness, the surface layer adheres well to the aluminum-based composite material, and the surface layer Exhibits appropriate solder wettability, so that good solderability can be obtained and unnecessary solder spread is suppressed, so that the number of soldering steps and cost can be reduced. Further, the base plate of the present invention can be easily formed by plating a base layer and a surface layer to a predetermined thickness and then performing deaeration treatment under a predetermined heating condition in a reducing atmosphere, a non-oxidizing atmosphere, or a vacuum. Can be manufactured. Therefore, it is useful for a substrate of a large-capacity IGBT module which easily generates heat, and has an industrially remarkable effect.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a wetting angle of solder.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Aluminum-based composite material 2 Underlayer 3 Surface layer 4 Solder after solidification α, β Angle between the edge surface of solder after solidification and Ni plating layer surface

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Morimasa Tanimoto 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. F-term (reference) 4K024 AA03 AA14 AB02 BA06 BB09 BB11 BC01 DA04 DA06 DA07 DA08 DB01 GA14 4K044 AA06 AB02 BA06 BB03 BC08 CA04 CA18 CA62

Claims (2)

[Claims] A Ni metal layer or a Ni-P alloy layer is plated as an underlayer on an aluminum-based composite material to a thickness of 3 μm or more, and a Ni—Co alloy layer or a Ni—C is formed thereon as a surface layer.
A base plate for electronic equipment made of a Ni-plated aluminum-based composite material, wherein at least one of the o-B alloy layer and the Ni-B alloy layer is plated to a thickness of 0.01 μm or more. 2. An aluminum base composite material is plated with a Ni metal layer or a Ni—P alloy layer to a thickness of 3 μm or more as a base layer, and a Ni—Co alloy layer or a Ni—C layer is formed thereon as a surface layer.
At least one layer of the o-B alloy layer or the Ni-B alloy layer is plated to a thickness of 0.01 μm or more, and then reduced to 200 ° C. or less per hour in a reducing atmosphere, a non-oxidizing atmosphere, or a vacuum. 200-500 ° C by heating at heating rate
A method for producing a base plate for an electronic device made of an aluminum-based composite material, comprising performing a deaeration treatment for maintaining the temperature at a predetermined temperature for a predetermined time.