JPH01116089A - Rust preventive treating solution - Google Patents

Abstract

PURPOSE:To produce a rust preventive treating soln. suitable for application to an electrical contact part by preparing a treating soln. contg. a PVA type high molecular compd. represented by a specified formula and a sulfur compd. such as thiobarbituric acid. CONSTITUTION:A rust preventive treating soln. contg. a PVA type high molecular compd. represented by the general structural formula (where X is OH, H, acetyl, alkyl or sulfone) and a sulfur compd. having an SH group or a double bond of sulfur, e.g., thiobarbituric acid or aminomercaptothiazole is prepd. PVA, polyvinyl formal or polyvinylcarbazole may be used as the PVA type high molecular compd. The treating soln. enables the rust preventive treatment of the electrical contact part of a connector, etc., with high reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an anti-corrosion treatment liquid used when applying anti-rust treatment to the contact portions of contact parts such as connectors.

(Prior Art) Contact portions of contact parts such as connectors are usually plated with a noble metal such as gold plating, which is stable against the external environment, for the purpose of ensuring electrical connection. However, recently, in order to reduce costs, the thickness of precious metal plating films has tended to be thinner, and as a result, the number of pinholes that occur in the plating film has increased, and corrosion products of the underlying metal are generated from these pinholes. There is a problem in that this increases the reliability of the electrical connection of the contact portion.

Therefore, in order to suppress the corrosion caused by these pinholes, it has been common practice to apply anti-rust treatment to the plating film. This anti-rust treatment is to fill pinholes formed in the plating film with a rust preventive agent (sealing effect) to prevent corrosion products from increasing on the underlying metal. Conventionally used rust-preventing treatment liquids are treatment liquids containing sulfur compounds such as thiobarbic acid and aminomercaptothiazole.

(Problems to be Solved by the Invention) However, in recent years, as the mounting technology for electronic components such as ICs has shifted to surface mounting, IC sockets and connectors used for surface mounting have changed.

Soldering is now subject to a heating process, such as a heating process, or a solvent cleaning process to remove residual solder flux from soldering. Therefore, the above-mentioned rust prevention treatment is required to have sufficient heat resistance and solvent resistance to withstand these heating and solvent cleaning steps. On the other hand, conventionally used anti-rust treatment liquids do not have sufficient heat resistance and solvent resistance, so heating or solvent cleaning can significantly reduce the anti-corrosion effect that suppresses corrosion of contacts. This is considered to be a problem in rust prevention treatment.

Therefore, the present invention was made to solve the above-mentioned problems, and its purpose is to enable rust-preventing treatment with high heat resistance and solvent resistance, and thereby to apply it to electrical contact parts such as connectors. An object of the present invention is to provide a rust-preventing treatment liquid that can perform highly reliable rust-preventing treatment.

(Means for solving problems) The present invention includes the following configuration to achieve the above object.

That is, a polyvinyl alcohol polymer compound having the general structural formula (CIl, CIl) and S such as thiobarbic acid, aminomercaptothiazole, etc.
11 groups or a sulfur compound having a sulfur double bond.

(Summary of the invention) Conventionally, what has been generally used as a rust prevention treatment liquid is:
S such as thiobarbic acid, aminomercaptothiazole, etc.
The present invention is characterized in that the polyvinyl-based polymer compound is added to this conventionally used antirust treatment liquid.

As the polyvinyl-based polymer compound, polyvinyl alcohol, polyvinyl formal, polyvinyl carbazole, polyvinyl pyrrolidinone, polyvinyl potassium sulfate, etc. can be used.

By using a rust-preventing treatment liquid to which these polyvinyl-based polymer compounds are added, the heat resistance and solvent resistance of the rust-preventing coating can be improved.

In addition, according to the rust prevention treatment using this rust prevention treatment liquid, 2
It has sufficient durability against heating at 00°C or higher and chlorocene cleaning, and sufficient rust prevention effect was observed in salt water jet and sulfur dioxide gas corrosion tests.

In addition, paraffins such as cercin can also be added to the above-mentioned anti-rust treatment liquid in order to improve the lubricity of the anti-rust treatment coating.

In addition, like the polyvinyl-based polymer compounds mentioned above, sorbitan ester ether-based surfactants, which have been newly recognized to be added to anti-rust treatment solutions to improve the heat resistance and solvent resistance of anti-rust coatings, have been added. Even if they are added at the same time, it is possible to obtain a rust prevention treatment solution having similar heat resistance and solvent resistance.

Examples of sorbitan ester ether surfactants include: - polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, and the like.

(Example) Examples of the antirust treatment liquid according to the present invention will be described below.

[Example 1] - Polyvinyl alcohol 0.01 mg/doaminomercaptothiazole 0.01 mg/1 [
Example 2] Polyvinyl formal 0.01mg/1
5-amino-1,3,/I thiadiazole-2thiol 0,01 mg/1 ・t) Li 0.01 mg/1 [Example 3] ・Polyoxyethylene Sorbitan monolaurate O,01 mg/Topolyvinyl Rubazole O,01mg/1・
5-amino-1,3,4thiadiazole-2thiol 0
, 01mg/ Tocercin 0.01mg/ 1
[Example 4] ・Polyoxyethylene sorbitan monolaurate 0.01mg/Topolyvinyl pyrrolidinone 0.01mg/1.5
-amino-1,3,4thiadiazole-2thiol0.
01mg/tocercin 0.01mg/1 Among the above-mentioned Examples, Example 1 and Example 2 contain a polyvinyl polymer compound and a conventionally used sulfur compound, and Example 3 and Example 4 contain a polyvinyl polymer compound and a conventionally used sulfur compound. is an example containing a polyvinyl-based polymer compound and a sorbitan ester ether-based surfactant. In addition, Example 2.3
．． In No. 4, cercin was added to improve the lubricity of the anticorrosive coating. When paraffins are added in this way, they are added after being dissolved in an organic solvent such as chlorocene or freon in advance.

In addition, in each of the above-mentioned Examples, 50% ethanol,
50% water was used as solvent.

In addition, sulfur compounds that are commonly used as antirust treatment solutions include 5-amino-1,3,4thiadiazole-2thiol, NN-diethyldithiocarbamic acid, aminomercaptothiazole, etc. Paraffins added to improve the lubricity of the coating include cercin, paraffin, and beeswax. In addition to the above-mentioned examples, these drugs can be used as appropriate.

Table 1 shows phosphor bronze base metal plated with nickel base plating.
Furthermore, the results of a salt water splash test were conducted using a gold-plated sample as a sample.The salt water splash test was performed when the sample was washed with 5% salt water for 48 hours, and when this salt water washing was performed while heating. The results were visually evaluated for each case in which no salt water washing was performed.

Among the treatment solutions in the table, "No treatment" means that the gold plating was tested without any rust prevention treatment, and "Conventional solution A" and "Conventional solution B" contain sulfur compounds that are conventionally used. In Example 1.2.3.4, the rust prevention treatment was performed using the rust prevention treatment liquid of each of the above-mentioned Examples. .

Table 1 In the table, O indicates that there is no corrosion at the visual level, Δ indicates that there is corrosion in some areas, and × indicates that there is corrosion throughout. It was found that for all of the products that were subjected to rust prevention treatment using the treatment liquid, the rust prevention effect did not deteriorate when washed with salt water, and that the rust prevention effect did not deteriorate even when heated.

In addition, the anti-corrosive coating formed using the anti-corrosive treatment solution of the above example is durable against heating at 200°C or higher and chlorocene cleaning, and is resistant to sulfur dioxide gas corrosion test (10 ppm, 96 It was confirmed that the rust prevention effect did not deteriorate even in tests such as (time).

(Effects of the Invention) As described above, the antirust treatment liquid according to the present invention has the following remarkable effects.

■ A rust-preventive coating that has a high pinhole sealing effect during rust-preventing treatment and has excellent heat resistance and solvent resistance can be obtained. As a result, the rust prevention effect does not deteriorate even after solder reflow, solvent cleaning, etc. are performed.

(2) Furthermore, by applying rust prevention treatment to the contact portions of connectors and the like using the above rust prevention treatment liquid, it is possible to improve the reliability and durability of the electrical connection of the contact portions.

Claims (1)

[Scope of Claims] 1. A polyvinyl alcohol polymer compound whose general structural formula is represented by ▲There are mathematical formulas, chemical formulas, tables, etc.▼;
A rust prevention treatment liquid characterized by containing a sulfur compound having an SH group or a sulfur double bond, such as thiobarbituric acid and aminomercaptothiazole. 2. Claim 1, wherein X is OH, H, an acetyl group, an alkyl group, or a sulfone group
Rust prevention treatment liquid described in section.