JPS6019630B2 - contact - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phosphor bronze contact plated with tin or a tin alloy, which is specially heated and melted after plating to have excellent peeling resistance under high-temperature use. The present invention relates to the above-mentioned contactor manufactured by performing a treatment.

Many connector contacts for circuit connection are used in electronic devices.

Materials for connector contacts include base materials such as beryllium steel, titanium steel, and phosphor bronze plated with gold, silver, etc. as surface contact metals, but from the viewpoint of cost and mass production, they are not suitable for consumer use. Not suitable for electronic equipment. In consumer electronic devices, contacts are mainly used in which phosphor bronze is used as the base material and tin or tin alloy is plated as the surface contact metal. However, when these contacts are used inside electronic devices, the temperature inside the device rises to around 10,000 ℃ due to heat generation due to electricity, so the contacts are exposed to such relatively high temperatures for a long time. It turns out.

Additionally, electronic devices are often subject to mechanical vibrations.
It has been recognized that under such usage conditions, the plating peels off from the base plate, resulting in poor contact. Peeling of the plated layer at high temperatures is a problem inherent to phosphor bronze-tin-based materials. As for the cause of this peeling, there is an opinion that a special compound is generated at the interface, but it has not yet been elucidated.

As a measure to prevent peeling, there are attempts to apply nickel underplating or thick copper underplating with two or more peaks, and proposals to use a special tin alloy containing silver, but from an economical point of view, etc. Undesirable.

The inventors of the present invention have found that the above-mentioned peeling problem can be solved by plating tin or a tin alloy onto a phosphor bronze base material and then subjecting the plated layer to heat melting treatment or melt plating.

Thus, the present invention includes plating a phosphor bronze base material with tin or a tin alloy, and then subjecting it to a heating and melting treatment,
provides a contact characterized by comprising a tin or tin alloy layer formed by hot-dip plating.

In the present invention, it is customary to mold a phosphor bronze strip into a contact after plating and heat-melting it. You can also do it.

Phosphor bronze includes various types of phosphor bronze specified by JIS as phosphor bronze for springs, and is in the range of 3 to 10% tin and 0.03 to 0.35% phosphorus. Phosphor bronze strip is
After predetermined purification treatments such as alkaline degreasing, electrolytic degreasing, pickling, and water washing, copper underplating is applied as necessary. In the present invention, peeling of the tin or tin alloy plating layer can be prevented by enhancing the steel subsurface plating. Plating of tin or a tin alloy can be carried out by electrolytic plating, electroless plating or hot-dip plating.

Tin alloys include lead, which is generally known as a solder material,
It includes those containing one or more of bismuth, cadmium, antimony, indium, ariminium, zinc, etc. The plating conditions remain the same as before. Examples of baths that can be used to solve the problem include alkaline baths using potassium stannate, sodium stannate, stannous chloride, etc., oxalate baths, fluoroborate baths, sulfate baths, and phenolsulfonic acid baths. can also be used. For melt plating, use a specified flux aqueous solution (
A typical method is so-called hot melt plating, in which the material is immersed in a 40oBe aqueous solution of ZnC12 for 1 to 2 seconds, then immersed in a hot melt plating tank for about 1 hour, and the thickness of the plating layer is adjusted appropriately by air blowing. Instead of immersing the flux in an aqueous solution, it is also possible to float the flux onto the molten layer and allow the flux to soak through the flux layer into the molten layer. The phosphor bronze strip plated with tin or tin alloy is then subsequently subjected to a heat melting process. The heat dissipation melting process is also called reflow process, and is carried out by heating the sand in a heating furnace such as a burner direct-fired furnace or an erema furnace at a furnace temperature of 550 to 1000 yen. With this process,
Remelting and fluidization of the tin or tin alloy layer takes place. However, it is not necessary to re-melt the melted material. Contacts made according to the present invention do not suffer from peeling of the plating layer during use at high temperatures.

For example, after holding for 60 wind hours at a temperature of 10,530 90
0 No peeling occurs at all even if a bending peel test is performed. Examples will be described below.

Example 1 A phosphor bronze strip for a spring was subjected to alkaline degreasing, electrolytic degreasing, pickling and neutralization, and then tin plating with a tin sulfate rating of 1.5 degrees.

The tin sulfate rating and plating conditions are as follows: tin sulfate sulfuric acid stannous sulfate 72/sulfuric acid
100 evenings / so high temperature
30 current density ships/dm2 The thus tinned strip was held at 650 qC for 5 seconds in a burner direct-fired heating furnace and then dried with warm air.

This strip was then molded into the shape of a contact. The thus prepared contact was heated in the atmosphere at 10500°C for 60 hours, and then subjected to a peel test by bending at 900°C, but no peeling of the plating layer was observed. Comparative Example 1 A contact was produced without subjecting the sample of Example 1 to heat-melting treatment.

When this was subjected to a peel test after being held for 36 hours at 105 oo, the plated layer peeled off. Example 2 A phosphor bronze strip for a spring was subjected to alkaline degreasing, electrolytic degreasing, pickling and neutralization, and then soldering with phenol sulfonic acid.

The plating bath composition and conditions were as follows. Stannous phenolsulfonic acid 160 t/lead phenolsulfonate 160 t/sphenol sulfonic acid
150 evenings/Kuke temperature
3oqo current density
3 A/d and then 650 oo in the Erema furnace.
After heating for 20 seconds, the mixture was allowed to cool.

The obtained mating material was molded into a contact, and after being held at 105 qo for 60 hours, a 90 o bending peel test was conducted.
In neither case did the solder plating layer peel off. Example
3 Phosphor bronze strips for springs are degreased with alkaline, electrolytically degreased, pickled, neutralized, washed with water, coated with a flux of 4 Yamashi zinc chloride aqueous solution, and immersed in molten tin at ordinary temperature at 3.20 pm. It is tinned to the thickness of a Buddha.

Thereafter, after molding into a contact, a peeling test was performed in the same manner as the tip after holding it for 60 hours at 105 pm, but no peeling of the plating layer was observed. Example 4 A phosphor bronze strip for springs pretreated in the same manner as in Example 3 was coated with flux and then immersed in a solder grade of 60% tin to 40% lead at a temperature of 300 qo to achieve two degrees of solder melt plating. went.

A peel test was conducted in the same manner as in Example 3, but no peeling of the plated layer occurred. As explained above, the present invention solves the problem of excessive exfoliation seen in conventional phosphor bronze-tin contacts with a very simple operation.

Claims (1)

[Scope of Claims] 1. It is characterized by comprising a phosphor bronze base material, a tin or tin alloy layer formed by plating tin or a tin alloy thereon, and then subjecting it to a heating and melting treatment. A contact element. 2. A contact comprising a phosphor bronze base material and a tin or tin alloy layer formed by melt-plating tin or a tin alloy thereon.