JPS61118908A - Lead for electric equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a lead wire for electrical equipment such as a lead wire for electronic components, and an inexpensive electrical conductor having excellent characteristics at °C.

[Prior Art] Conventionally, lead wires for electronic components 2 such as solid resistors and diodes, or conductors for wiring electronic devices, have been coated with tin or tin on core conductors such as copper wires, copper alloy wires, or copper-coated steel wires. So-called solder-plated wires have been used which have been subjected to tin-lead alloy plating to improve solderability.

When such solder-plated wire is used as a lead wire for electronic components, it is cut to a predetermined length and then assembled with other materials that make up the electronic component, then molded with ceramic or resin, and then printed or otherwise printed to create a 200mm wire. Subjected to heat treatment at temperatures above ℃. It is known that when a solder-plated wire is subjected to such heat treatment, the copper and tin or tin-lead alloy on the surface of the core conductor of the solder-plated wire easily undergo thermal diffusion, resulting in a decrease in solderability. As a countermeasure to this, heat diffusion is applied to copper or copper-covered steel wires.
, a tin or tin-lead alloy plating with a base layer of Ni-8n or the like was performed. This method was adopted because Ni itself has excellent corrosion resistance and is a relatively inexpensive material.

[Problems to be solved by the invention] However, nickel and tin or tin-lead alloy are
When subjected to heat treatment at 50° C. or higher, a brittle alloy of nickel and tin is formed, and when stress such as bending is applied to the lead wire, the tin or tin-lead alloy layer peels off. In particular, as the range of applications for electronic devices has expanded in recent years, this phenomenon has often occurred not only due to heat treatment during assembly of electronic components, but also due to thermal history in the usage environment.

[Means and effects for solving the problems] The present invention has been made in view of the above-mentioned circumstances, and it not only improves solderability after heat deterioration, but also improves solderability after being incorporated into electronic equipment. The purpose is to provide a lead wire for electronic components that improves mechanical strength, and its gist is to provide a lead wire made of iron or iron alloy on a conductor made of copper, copper alloy, or copper-coated wire. After that, a solder plating or tin plating layer is provided. Here, the thickness of the iron or iron alloy plating layer is preferably 0.05 to 1.0 μm. This is because the plating layer is provided for the purpose of suppressing mutual diffusion between the tin or solder plating layer and the base copper, copper alloy, or copper-coated wire. If the alloy plating layer is provided with a thickness exceeding 1.0μ, the plating layer will crack when subjected to processing such as bending, and if the thickness is less than 0.05μ, it will not have the effect of suppressing diffusion. That's because you get very little.

[Example] Next, the present invention will be explained in more detail with reference to Examples.

Example 1 A 0.6 mφ conductor 1 made of copper was pretreated with degreasing and pickling, and then electroplated with 80% Fe-Ni alloy 2 (nickel sulfate, nickel chloride, ferrous sulfate, boron). A plating bath consisting of acids and additives) was provided at a thickness of 0.3 μm, and a tin plating layer 3 was added at a thickness of 7 μm from a tin borofluoride plating bath.
The first step is to create a lead wire by providing it with a thickness of
(see figure). In addition, as comparative example 1, 0.6Mφ made of copper
After subjecting the conductor 1 to the same pretreatment as described above, a lead wire was prepared having a tin plating 3 of 7 μm thick from a tin borofluoride plating bath (see FIG. 2).

The tin-plated lead wire thus produced was placed in a constant temperature bath at 150° C. to undergo thermal deterioration. Thereafter, it was bent back to 90° C. using a 0.3R jig, and the adhesion was evaluated based on the presence or absence of peeling of the tin plating layer.

On the other hand, the lead wire after thermal deterioration was
Solderability was examined by the method of 02D-208B. Evaluation was performed based on wettability.

Example 2 An iron plating layer was applied to a thickness of 0.2μ by electroplating from a sulfuric acid bath on a copper conductor pretreated in the same manner as in Example 1, and tin plating was further applied to a thickness of 7μ. A plated lead was created.

On the other hand, for comparison, Ni plating, which is used to suppress the diffusion of copper in silver plating, etc., was applied as the base of the tin plating layer to a thickness of 0.2μ by electroplating, and then the tin plating was applied. A tin-plated lead wire was created by providing a thickness of 7 μm (Comparative Example 2).

Adhesion and solderability to these lead wires were evaluated in the same manner as in Example 1.

The results obtained in Examples 1 and 2 are summarized in Table 1.

In Table 1, adhesion is judged by ○: no peeling, ×: peeling of the tinned layer, and solderability is judged by 0295% or more solderability, △: 94-80% solder. Attachability, X: 80%
The solderability was below.

[Effects of the Invention] As explained above, the present invention provides a lead wire that not only improves solderability after heat deterioration but also improves mechanical strength (adhesion) after being incorporated into an electronic device. can be provided.

That is, thermal diffusion between the tin or solder plating layer and copper is fast, and several μm of Cu, Sns (77 layers), and CLJ3 Sn (6 layers) are formed at 150° C. for about 100 hours. Also, when using Ni plating, which is used in silver-plated copper wire, etc., the N1 layer and tin.

Thermal diffusion between NiE and copper is surprisingly fast, and as can be seen from the results shown in Table 1, the solderability is significantly reduced.

On the other hand, the reason why iron or iron alloy is more effective as a thermal diffusion barrier is thought to be because iron is less soluble in copper and tin than j'Ji.

As a result, the heat resistance properties of tin or solder plated lead wires have been significantly improved, and reliability has been significantly improved. Furthermore, since thermal diffusion between the tin or solder layer and copper is suppressed, the plating thickness of the tin or solder layer can be made even thinner, which has an extremely large economical effect.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a lead wire for electronic components according to the present invention, and FIG. 2 is a sectional view showing an example of a conventional lead wire for electronic components. 1... Copper conductor, 2... Fe alloy or Fe plating layer. 3...Tin plating layer

Claims (2)

[Claims] (1) A lead wire for electrical equipment, characterized in that a conductor made of copper, copper alloy, or copper-coated wire is provided with an iron or iron alloy plating base layer, and then a solder plating or tin plating layer is provided. (2) The thickness of the iron or iron alloy plating base layer is 0.05~
The lead wire for electrical equipment according to claim 1, characterized in that the lead wire has a diameter of 1.0μ.