JP2690614B2 - Method for forming metal plating layer without blister on Cu and Cu alloy rolled material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a metal-plated layer on a surface of Cu and a rolled Cu alloy material, which is free from blistering even in a heating environment. is there.

[Conventional technology]

In general, rolled materials of Cu and Cu alloys are prepared by a normal melting method to prepare a molten metal having a predetermined purity or composition, cast into ingots, hot rolled under the same normal conditions, and then face-cut, and then cut. Cold rolling, annealing, pickling, or mechanical grinding steps are set as one cycle, and usually this is repeated for two or more cycles, and further, finish rolling and strain relief annealing are performed to produce the metal plating. It is well known that metal plating is performed on this surface in a state of being mechanically ground or degreased.

It is also known that these metal-plated Cu and rolled Cu alloy materials are widely used as lead frames and substrates, which are structural members of semiconductor devices, and terminals and connectors.

[Problems to be solved by the invention]

On the other hand, with the recent increase in density and size of semiconductor devices, the heat generation of semiconductor devices tends to increase, but in the lead frame and substrate composed of the above-mentioned conventional metal-plated Cu and Cu alloy rolled material. In the current situation, blisters are likely to occur on the metal-plated surface due to the heat generation, and there is a problem in terms of reliability.

[Means for solving the problem]

Therefore, the present inventors, from the viewpoint as described above, Cu and Cu the metal plating layer that does not generate blisters even when heated.
As a result of conducting research to form on the surface of rolled alloy material, the surface roughness of conventional Cu and rolled Cu alloy material before plating treatment is the center line average roughness of JIS B0601 standard (cutoff value: 0.8 mm): Ra is about 0.15 to 0.3 μm, which is relatively rough, but Ra: Ra: 0.1 μm or less surface roughness (maximum height: Rmax is 1.0
If the metal plating layer formed on the surface of the Cu and Cu alloy rolled material is heated, the blistering will not occur at all if the metal plating is performed under normal conditions after polishing to (μm or less). I got the research result that I could not.

This invention was made based on the above-mentioned research results, and the surface of Cu and Cu alloy rolled material which has been subjected to strain relief annealing after final finish rolling was 0.1 μm or less in Ra of JIS / B0601 standard. It is characterized by a method of forming a metal plating layer on the surface of Cu and Cu alloy rolled material that does not cause blistering even when heated by polishing the surface roughness of I have.

The surface roughness of the Cu and the rolled Cu alloy material in the method of the present invention is empirically determined. As described above, when the surface roughness exceeds Ra: 0.1 μm, the metal plating layer is boiled by heating. Therefore, the surface roughness is set to Ra: 0.1 μm or less so that blisters do not occur in the metal plating layer.

〔Example〕

Next, the method of the present invention will be specifically described with reference to examples.

Cu and Cu alloy melts having the compositions shown in Table 1 were prepared by a normal melting method, and the thickness was 160 mm and the width was 450 mm.
× Length: Cast into an ingot having a dimension of 2400 mm, homogenize the ingot by keeping it at 850 ° C for 1 hour, and then start hot rolling at a predetermined temperature within the range of 850 to 750 ° C. Thickness: 11 mm hot rolled sheet, and the hot rolled sheet is chamfered to remove scales on the upper and lower surfaces to a thickness of 10 mm, then cold rolled at a reduction ratio of 50% or more, 350 After repeating the process twice, one cycle consisting of a series of steps of intermediate annealing under the condition of holding for 2 hours at a predetermined temperature within the range of up to 600 ° C, and pickling, the final reduction rate shown in Table 1 Finish rolling is performed to obtain a cold-rolled sheet having the same thickness as shown in Table 1,
This is subjected to strain relief annealing of holding at 350 ° C for 1050 seconds, and Cu
And rolled Cu alloy rolled material, and further, the surface of these various Cu and Cu alloy rolled material was sprayed with SiC abrasive grains of a predetermined grain size to adjust the surface roughness of the nonwoven fabric, and a pair of upper and lower diameters of 300 mm were used. Using a polishing device attached to the roll surface,
Downstream Polishing under the same conditions (roll rotation and passing direction are the same), roll rotation speed: 950 rpm, roll pressure: 0.5 watts per 1 mm roll width, and the surface roughness shown in Table 1 On the surface of this, by the usual electroplating method,
Inventive methods 1 to 10 and conventional methods 1 to 10 were carried out by forming an Ag, Au, or Ni plating layer having a thickness of 2 μm.

Next, various metal-plated Cu and
The rolled Cu alloy material was also heated under the conditions shown in Table 1, and the number of blisters generated in the metal plating layer after heating was measured, and the number of blisters per unit area is shown in Table 1.

〔The invention's effect〕

As shown in Table 1, in the methods 1 to 10 of the present invention,
A metal plating layer that does not generate blisters even when heated can be formed on the surface of Cu and Cu alloy rolled materials, whereas Cu and Cu alloys with a relatively rough surface roughness of Ra: 0.15 to 0.3 μm Conventional method 1 to form a metal plating layer on rolled material
It is clear that in 10 the generation of many blisters on the metal plating layer cannot be avoided.

As mentioned above, according to the method of the present invention, Cu and Cu
By setting the surface roughness of Ra: 0.1 μm or less on the surface of the rolled alloy material, it is possible to form a metal plating layer that does not generate blisters even when exposed to heating. Therefore, the resulting metal plating Cu and Since Cu alloy does not generate blisters even when it is applied as a structural member exposed to higher heat due to higher density and larger size of semiconductor devices, it is industrially useful, such as contributing to improved reliability. It has an effect.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaaki Otsubo 128-7 Ogimachi, Aizuwakamatsu, Fukushima Prefecture Wakamatsu Seisakusho, Mitsubishi Shindoh Co., Ltd. (56) Reference JP-A-62-267492 (JP, A)

Claims (1)

(57) [Claims] 1. The surface of Cu and Cu alloy rolled material that has been subjected to final finish rolling and then subjected to strain relief annealing is subjected to center line average roughness (cutoff value: 0.8) of JIS B0601 standard.
mm): Ra is polished to a surface roughness of 0.1 μm or less, and the polished surface is plated with metal under normal conditions to form a blistering-free metal plating layer on rolled Cu and Cu alloy materials. Method.