JP2726434B2 - Sn or Sn alloy coating material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is based on Cu or Cu alloy,
The present invention relates to a Sn or Sn alloy coating material for electronic components and equipment, which has a coating layer of i, Co or an alloy containing them, and a coating layer of Ag or an Ag alloy and has an outermost layer provided with a coating layer of Sn or a Sn alloy.

[Conventional technology and its problems] Composite conductors coated with Sn or Sn alloy on Cu or Cu alloy substrate have excellent solderability and corrosion resistance such as Sn in addition to the characteristics of the substrate, and electrical connection characteristics Is also excellent,
It is used as electronic and electric parts such as connectors, terminals and other contact parts, lead parts such as lead frames and lead wires, board circuits and wiring cable conductors.

These materials are usually coated directly on a Cu or Cu alloy substrate with Sn or Sn alloy by electroplating, hot-dip plating, cladding, etc., or after providing a Cu, Ni layer etc. as an intermediate layer, n or Sn alloy Is used.

When the above materials are used for electronic and electric parts, the temperature of the materials is 100 ℃ due to external or self-generated heat during use.
In general, the temperature rises to about 120 ° C or more due to circumstances such as the increase in self-heating, the difficulty in dissipating heat, and the proximity to other heat-generating parts, etc. It is being used.

However, at this operating temperature, in conventional Sn or Sn alloy coating materials using Cu as an intermediate layer, Cu reaches the surface due to the diffusion of Cu and Sn and causes oxidation, and the pure Sn layer or pure solder layer is diffused. The alloy layer is lost and becomes an alloy layer, the appearance is impaired, and the characteristics are deteriorated such as an increase in contact resistance. In the case where the intermediate layer is made of Ni, N
There was a problem that an i-Sn diffusion layer was formed and contact resistance increased.

[Problems to be solved by the invention]

As a result of studying the above problems, the present invention provides a Sn or Sn alloy coating material having good appearance and contact characteristics over a long period of time, with little increase in contact resistance without oxidative discoloration of the surface, regardless of use at high temperatures. It was developed.

[Means and actions for solving the problem]

The present invention provides a first coating layer of Ni, Co or an alloy containing these on a Cu or Cu alloy substrate surface, and on the surface thereof, Ag or
A second coating layer of an Ag alloy is provided, and Sn or Sn is further provided on the surface thereof.
Sn or a Sn alloy coating material provided with a Sn alloy coating layer, wherein the thickness of the first coating layer is 0.05 to 1.0 μm and the thickness of the second coating layer is 0.005 to 0.5 μm. .

That is, the present invention provides a first coating layer of Ni, Co or an alloy containing these on the surface of a substrate made of Cu or Cu alloy, and the Cu or Cu alloy of the substrate is coated on the outermost Sn or Sn alloy coating layer. It prevents diffusion and further provides a second layer of Ag or an Ag alloy coating layer to prevent the metal or alloy of the first coating layer from diffusing into the outermost Sn or Sn alloy layer. The outermost Sn or Sn alloy coating layer is not subjected to diffusion alloying for a long period of time, preventing oxidative discoloration of the surface and reducing an increase in contact resistance.

In the present invention, the Cu or Cu alloy base material, other than pure copper, brass, bronze, copper bronze, phosphor bronze, cupronickel, copper alloys for various lead frames, and the like, and Sn or Sn
As the alloy, a normal solder alloy other than Sn can be used. As the coating method of the above-mentioned coating layer, electroplating, electroless plating, vapor deposition, PVD, CVD and the like can be applied. It is necessary that the thickness of the first coating layer of Ni, Co or an alloy containing them is 0.05 to 1.0 μm, and if the thickness is less than 0.05 μm, the effect of preventing diffusion is small, and if the thickness is more than this, workability is reduced. . Also
It is necessary that the thickness of the Ag or Ag alloy coating layer be 0.05 to 0.5 μm. If the thickness is less than this, the diffusion preventing effect is not sufficient, and if it exceeds 0.5 μm, it is economically undesirable. Further, the thickness of the outermost Sn or Sn alloy coating layer is a thickness of a conventionally used material, and is suitably in the range of 0.5 to 10 μm.

In addition, as the first coating layer, other than Ni and Co, Ni-Cu, Ni-C
r, Ni-Zn, Ni-P, Ni-Cu-P, Co-P, Ni-Co, Ni
-Alloys such as -Fe can be applied, and Ag as well as Ag is used as the second coating layer.
Alloys such as -In, Ag-Sn, Ag-Zn, and Ag-Ni can be applied.

According to the present invention, as described above, the first coating layer prevents the diffusion of the Cu or Cu alloy base material and the outermost Sn or Sn alloy coating layer, and the second coating layer further comprises the first coating layer and the outermost layer. The purpose of the present invention is to prevent the Sn or Sn alloy coating layer from diffusing to eliminate the oxidative discoloration of the surface of the outermost Sn or Sn alloy coating layer and to prevent an increase in contact resistance, and thus to significantly reduce the deterioration of contact characteristics.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described.

Example 1 A 0.3 mm thick 7/3 brass strip was subjected to electrolytic degreasing, pickling, and water washing.
Using a sulfamic acid bath, plating thickness 0.05, 0.2, 0.5,
Apply 1.0μm Ni plating, and further use a bluing bath on this surface to make the plating thickness 0.005, 0.05, 0.2, 0.5μm Ag
Plating is applied, and the thickness of this surface is increased to 1.
A bright Sn plating of 0 μm was performed to produce a Sn plating coating material.

Comparative Example 1 An Sn plating coating material was produced in the same manner as in Example 1 except that the Ni plating thickness was 1.2 μm and that Ag plating was not performed.

Comparative Example 2 An Sn plating coating material was produced in the same manner as in Example 1 except that the Ni plating was not applied and the Ag plating thickness was changed to 0.2 μm.

Comparative Example 3 An Sn plating coating material was produced in the same manner as in Example 1, except that the Ni plating thickness was 0.03 μm and the Ag plating thickness was 0.2 μm.

Comparative Example 4 An Sn plating coating material was produced in the same manner as in Example 1 except that the Ni plating thickness was 0.5 μm and the Ag plating thickness was 0.001 μm.

Comparative Example 5 An Sn plating coating material was produced in the same manner as in Example 1 except that Ni and Ag plating were not performed and Cu was plated to a thickness of 0.6 μm in a bluing bath.

Comparative Example 6 An Sn plating coating material was produced in the same manner as in Example 1 except that the plating thickness of the Ni plating was 2.0 μm.

Example 2 A phosphor bronze strip having a thickness of 0.2 mm was electrolytically degreased, pickled, and washed with water.
Using a Watt bath, Ni was plated 0.5 μm, and the surface was Ag-I
The n-plating was applied in a bluing bath at 0.2 μm, and the surface thereof was subjected to solder plating using a phenolsulfonic acid bath to a thickness of 1.2 μm to produce a Sn alloy coating material.

Example 3 A Sn alloy-coated material was produced in the same manner as in Example 2, except that 0.5 μm of Sn—Ni alloy plating was applied using a chloride-fluoride bath instead of Ni.

Each sample prepared in the above Examples and Comparative Examples was subjected to a 90 ° bending test of appearance, contact resistance, pure Sn layer thickness, and 0.2R after heating in air in a 150 ° C. air bath for 4 weeks. . Table 1 shows the results.

As is clear from Table 1, all of the coating materials of Examples 1 to 3 of the present invention have good appearance without discoloration of the surface in appearance, have low contact resistance, and have a large residual Sn thickness.
On the other hand, in each of Comparative Examples 1 to 5, it can be seen that the discoloration of the appearance surface is large, the contact resistance is large, and the residual Sn thickness is very small.

Comparative Example 6 was not so good in 90 ° bending cracks.

〔effect〕

As described above, according to the present invention, the surface discoloration is small even at a high temperature, and the contact characteristics are extremely deteriorated. It is a material that can obtain a Sn or Sn alloy coating material and has industrially remarkable effects.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location H01L 23/50 H01R 13/03 A H01R 13/03 H05K 1/09 C H05K 1/09 H01G 1 / 14 F

Claims (1)

(57) [Claims] 1. A first coating layer of Ni, Co or an alloy containing them is provided on the surface of a Cu or Cu alloy substrate, a second coating layer of Ag or an Ag alloy is provided on the surface, and Sn or Sn is further provided on the surface. Sn or a Sn alloy coating material provided with a Sn alloy coating layer, wherein the thickness of the first coating layer is 0.05 to 1.0 μm and the thickness of the second coating layer is 0.005 to 0.5 μm. Or
Sn alloy coating material.