JPH0119478B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to copper-tin based contacts, and in particular to copper-tin contacts which do not cause peeling problems of the tinned layer at high temperatures and do not deteriorate during use under harsh conditions. ~1% by weight tin and 0.006-0.1% by weight
The present invention relates to a novel contact whose base material is tinned copper containing phosphorus, and a method for manufacturing the same. Background of the Invention Generally, contacts for circuit connections such as terminals and connectors are plated with gold or silver as a surface contact metal on a copper alloy base material to reduce contact resistance. For this reason, it is not suitable for use in general consumer electronic equipment such as automobile junction blocks. Currently, in general consumer electronic devices, inexpensive tin or tin alloys are mainly used as surface contact layers instead of gold or silver. When a contact is incorporated into an automobile junction block, the contact is heated to an ambient temperature of approximately 150° C. and is often exposed to a corrosive atmosphere. In addition, it is subjected to mechanical vibration for a long period of time. Conventionally, brass has been used as a copper alloy base material for contacts in terms of electrical (thermal) conductivity, corrosion resistance, spring properties, etc., which satisfies these requirements.
Balance Zn, Pb≦0.05%, Fe≦0.03%; Electrical conductivity 28%
IACS, thermal conductivity 0.29 cal/cm ² /cm/sec/°C) was used. However, since a large amount of heat is released in an automobile engine compartment, the temperature of the junction block increases as described above. In such an environment, a copper alloy base material with better electrical (thermal) conductivity is desired. Attempts have been made to use phosphor bronze and various other copper alloys, but the tin or tin alloy layer as the surface contact metal does not peel off (no contact failure or disconnection occurs) under the severe conditions mentioned above.
This is an essential requirement for a contactor, and no material that fully satisfies this has yet been obtained. SUMMARY OF THE INVENTION In view of the current situation, the present inventor has conducted extensive research in order to develop a copper-tin based contact particularly suitable as a contact for a junction block for an automobile.
As a result, it was found that it is better to use a copper alloy, generally called tinned copper, containing 0.08 to 1% by weight of tin and 0.006 to 0.1% by weight of phosphorus as the base material. Normal copper-tin contacts are usually plated with copper undercoating to improve their appearance and corrosion resistance, but in the present invention, tin is directly applied onto the base material without applying copper underplating. Alternatively, it has been found that tin alloy plating is better from the viewpoint of preventing peeling. Furthermore, as a manufacturing method of the above-mentioned contact, tin or a tin alloy is electroplated on a copper alloy base material, followed by heat melting (reflow) treatment, or tin or a tin alloy is melt-plated. It has been found that this method has the effect of further enhancing the peeling prevention effect and also improving the drawback of tin or tin alloy plating that contact resistance increases due to surface oxidation in such high-temperature usage environments. Thus, the present invention provides 0.08 to 1% by weight of tin;
Provided is a contact having a base material made of a copper alloy consisting of 0.006 to 0.1% by weight phosphorus, the balance copper and unavoidable impurities, and having a tin or tin alloy plating layer as the surface contact metal. Furthermore, the present invention involves electroplating tin or a tin alloy on a copper alloy base material consisting of 0.08 to 1% by weight tin, 0.006 to 0.1% by weight phosphorus, and the balance copper and unavoidable impurities, followed by heating and melting treatment. The present invention also provides a method for manufacturing a contact, which is characterized by carrying out the above steps or melting and welding tin or a tin alloy. DETAILED DESCRIPTION OF THE INVENTION Contacts are usually produced by plating and heating melting a strip, sheet, etc. of a copper alloy base material, and then molding the base material sheet into a contact. There is no preclude from plating and heating melting after molding into a mold. Here, the explanation will be based on the former. The base material copper alloy strip used in the present invention is
The Sn content is 0.08-1% by weight, and the P content is
0.006-0.1% by weight, and the balance consists of copper and unavoidable impurities. This is commonly called tinned copper. The reason why the Sn content is 1% by weight or less is that if it exceeds 1% by weight, the conductivity will be 60%.
This is because the corrosion resistance becomes lower than IACS and the effect of improving corrosion resistance is saturated. Further, the tin content needs to be 0.08% by weight or more so that the softening temperature does not become too low. P content is required to be 0.006% by weight or more in order to function as a deoxidizing agent, and on the other hand, if it exceeds 0.1% by weight, the conductivity will decrease by 60%.
The corrosion resistance decreases below IACS and the effect of improving corrosion resistance is saturated. The preferred composition is 0.08-0.12 wt% Sn and
It contains 0.006 to 0.012% by weight of P. As mentioned at the outset, brass and phosphor bronze have generally been used as contact base materials for automobile junction blocks. However, although brass is inexpensive, it has drawbacks in terms of thermal conductivity, corrosion resistance, etc., and is particularly susceptible to stress corrosion cracking. In addition, phosphor bronze is expensive and has poor electrical (thermal) conductivity. As a result of many studies, it has been found that tin-containing copper having the above composition is particularly suitable as a contact base material for automobile junction blocks. This copper alloy base material strip is subjected to predetermined purification treatments such as alkaline degreasing, electrolytic degreasing, pickling, and water washing in a known manner, and then is plated with tin or a tin alloy as a contact metal. Conventionally, it has been customary to apply copper underplating to improve the appearance and corrosion resistance of tin or tin alloy plating. Therefore, the inventor initially applied copper plating to tin-containing copper as an intermediate layer, then plated tin or a tin alloy on top of that and molded it into a contact, and used it in a simulated engine room environment. It was observed that the tin or tin alloy plating layer peeled off. In order to solve this problem, after repeated trials, it was surprisingly found that it is better to directly plate the base material with tin or tin alloy without applying a copper undercoat. The copper base treatment that has been conventionally performed is not necessary in the present invention.
On the contrary, it is harmful. Plating of tin or a tin alloy can be carried out by electrolytic plating, electroless plating or hot-dip plating. Tin alloys include lead, bismuth, cadmium, which are generally known as solder materials,
It includes those containing one or more of antimony, indium, aluminum, zinc, etc. The plating conditions remain the same as before. Electrolytic plating baths include alkaline baths using potassium stannate, sodium stannate, stannous chloride, etc., oxalate baths,
Any of a boaring bath, a sulfate bath, a phenolsulfonic acid bath, etc. can be used. For melt plating, use a specified flux aqueous solution (40°Be aqueous solution of ZnCl ₂ ).
A typical method is so-called hot-melt plating, in which the plated layer is immersed in water for 1 to 2 seconds, then immersed in a hot-melt plating bath for about 10 seconds, and the thickness of the plated layer is adjusted appropriately by air blowing. Instead of dipping into an aqueous flux solution, the flux may be floated onto the melted layer and immersed through the flux layer into the melted layer. The copper alloy strip plated with tin or tin alloy is then subjected to a heat melting process. Heat melting treatment is also called reflow treatment, and involves heating the material in a heating furnace such as a burner direct-fired furnace or an Elema furnace at a temperature of 500 to 800 degrees Celsius above the melting point of tin, that is, 231 degrees Celsius, for an appropriate period of 3 to 20 seconds. It is carried out by. This treatment causes remelting and fluidization of the tin or tin alloy layer. However, it is not necessary to re-melt the melted material. The heat-melting treatment described above further improves the heat-resistant peelability and also prevents an increase in contact resistance due to surface oxidation during high-temperature use. Contacts made in accordance with the present invention do not suffer from peeling of the plating layer during use at high temperatures. for example,
After holding at temperature of 105℃, 150℃, 180℃ for 600 hours
Even when a 90° bending peel test is performed, no peeling occurs at all.
Furthermore, there is almost no increase in contact resistance due to surface oxidation. Furthermore, in actual tests where it was incorporated as a connector into an automobile electrical circuit junction block, it exhibited extremely good conductive performance. Effects of the Invention The present invention provides a contact that does not cause long-term failure under harsh operating environments including heat, vibration, and corrosive atmospheres, such as automobile junction blocks. Examples and Comparative Examples Copper alloys with various components that are the base materials of the contacts of the present invention shown in Table 1 were rolled into plates with a thickness of 1.0 mm.
After annealing this, the thickness is further reduced by cold rolling.
A 0.8mm plate was used. Next, this was subjected to the steps of alkaline degreasing, electrolytic degreasing, pickling, and neutralization, and then various platings shown in Table 1 above were applied. The plating conditions are shown below. Electro-tinning bath composition: tinnous sulfate 55g / sulfuric acid 100g / cresolsulfonic acid 100g / gelatin 2g / beta-naphthol 1g / bath temperature 25°C current density 3A/dm ^2Electric solder plating bath composition stannous phenolsulfonic acid 160g / Lead phenolsulfonate 160g / Phenolsulfonic acid 150g / Bath temperature 30℃ Current density 3A/dm ² Hot-dip tin plating bath Temperature 320℃ Flux 40゜Be zinc chloride aqueous solution copper plating (base plating shown in comparative example) Bath Composition: 210 g of copper sulfate / 100 g of sulfuric acid / Bath temperature: 30°C Current density: 5 A/dm ² Reflow treatment The plated plate was held at 650°C for 5 seconds in a small Matsufuru heating furnace, and then cooled with water. The various plating materials thus created were further molded into the shape of a contact. Table 1 shows the results of a peel test performed by bending the contacts at 90° after heating them in the atmosphere at 105°C, 150°C, and 180°C for 600 hours. Regarding the contacts heated to 105℃, we measured the contact resistance due to the oxide film formed by heating in the air for 600 hours, and also measured the strength of the base material by tensile testing, and measured the electrical conductivity (heat dissipation). %
IACS) and similarly shown in Table 1. As is clear from the above Examples and Comparative Examples, the contact produced according to the present invention can be heated at 105°C, 150°C and
The plating layer does not peel off even after heating at 180°C for 600 hours. It has high electrical conductivity and does not reduce contact reliability even when used at high temperatures for long periods of time. In particular, those in which the plating layer has been subjected to reflow treatment or melt plating are extremely excellent, as there is little increase in contact resistance due to surface oxidation.

[Table] * Electricity refers to electroplating, and fusion refers to fusion plating.

Claims (1)

[Claims] 1. A copper alloy consisting of 0.08 to 1% by weight of tin, 0.006 to 0.1% by weight of phosphorus, and the balance copper and unavoidable impurities as a base material, and a tin or tin alloy plating layer as a surface contact metal. Contactor included. 2 Electroplating tin or a tin alloy on a copper alloy base material consisting of 0.08 to 1% by weight tin, 0.006 to 0.1% by weight phosphorus, and the balance copper and unavoidable impurities, followed by heating and melting treatment, or A method for manufacturing a contact, which comprises melt-plating tin or a tin alloy.