JPH0465497A - Flux-cleaning agent - Google Patents

Abstract

PURPOSE:To obtain a flux-cleaning agent substitutable for conventional fluorocarbon-based or chlorine-based solvent having low toxicity and a high flash point without fear of ozone decomposition nor environmental pollution of water system containing a nonionic surfactant and dimethyl adipate as essential components. CONSTITUTION:The aimed cleaning agent for removing flux after soldering contains (A) preferably 1-30 wt.% polyoxyethylene-based nonionic surfactant such as preferably a polyoxyethylene alkyl ether or polyoxyethylene fatty acid ester and (B) preferably 50-99 wt.% dimethyl adipate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flux cleaning agent for removing flux applied during solder bonding to strengthen the bonding force between the solder and a base material after solder bonding.

[Conventional technology]

Conventionally, in the field of electrical and electronic industries, flux is applied in advance in order to firmly bond solder and base material in the manufacturing process of printed circuits or printed wiring boards. If this flux remains on the printed circuit or printed wiring board, it will cause poor conductivity or corrosion, so it is usually washed off with an organic cleaning agent after soldering. Freon 113 or methyl chloroform has conventionally been used as this cleaning agent. These solvents have a great ability to dissolve flux and are nonflammable, so they are widely used.

[Problem that the invention is trying to solve]

However, as society's awareness of environmental issues increases, there is a movement to regulate the discharge of environmentally destructive substances into the atmosphere and water systems. For example, fluorocarbon solvents (5 types of specified fluorocarbons:
CFCII, CFCl2, CFCII3, CFCII
4, CFCII5) and methylchloroform are being restricted in their use as ozone layer depleting substances.

Under such circumstances, the industry that uses Freon 113 or methyl chloroform is in urgent need of a flux cleaning agent that can replace these solvents.

[Means to solve problems]

The present inventors have discovered that Freon 1 used in flux cleaning agents.
13. As a result of repeated research on cleaning agents to replace methyl chloroform, we found that a composition containing a nonionic surfactant and dimethyl adipate as essential components is comparable to conventional flux cleaning agents (Freon 113 and methyl chloroform). We have discovered that this is a cleaning agent that exhibits moderately high cleaning performance and good finish, and based on this knowledge, we have accomplished the present invention.

That is, the present invention is a flux cleaning agent characterized by containing (1) a nonionic surfactant and (2) dimethyl adipate as essential components.

The concentration of the nonionic surfactant used in the present invention is 1 to 3.
Preferably, it is in the range of 0% by weight.

Examples of nonionic surfactants used in the present invention include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyethylene nonylphenyl Ether, polyoxyethylene alkylphenyl ether such as polyoxyethylene octylphenyl ether; polyoxyethylene polyoxypropylene block polymer, polyoxysorbitan fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, etc. polyoxyethylene derivatives; examples include sorbitan fatty acid esters and glycerin fatty acid esters. Although each of these can be used alone, a combination of two or more types is preferably used.

More preferably, a combination containing one or more polyoxyethylene nonionic surfactants such as polyoxyethylene alkylethyl or polyoxyethylene fatty acid ester is used. The number of moles of the ethylene oxide moiety added in the polyoxyethylene nonionic surfactant is preferably 3 to 40, more preferably 10 to 2.
It is 0.

The concentration of dimethyl adipate used in the present invention is 50
It is preferably in the range of 99% by weight.

In the combination of dimethyl adipate and nonionic surfactant in the present invention, the type and concentration of the surfactant depend on the material and form of the object to be washed, the type of dirt, etc.
It can be changed arbitrarily. If any one of the essential components is missing, the finish will deteriorate due to poor flux cleaning performance or water rinsing performance. or,
Only by combining two essential components can a practical cleaning agent that is environmentally safe, pose no problems in terms of occupational hygiene, and rival the conventional fluorocarbon-based and chlorine-based flux cleaning ability be obtained. Furthermore, it is possible to add various stabilizers and additives to the composition of the present invention in order to maintain the stability of the liquid and improve the stability against the objects to be washed, or to improve the dissolving power. Examples of agents and additives include hydrocarbons, alcohols, ethers, acetals, esters, ketones, fatty acids, nitroalkanes, amines, amides, glycols, aminoethanols, and benzotriazole. etc.

Furthermore, it is also possible to add an anionic surfactant or a cationic surfactant to the composition of the present invention, if necessary.

〔Example〕

Hereinafter, the present invention will be specifically explained using Examples and Comparative Examples. The cleaning methods in Examples and Comparative Examples are as follows.

Cleaning method in Examples (Fig. 1) - ■ Ultrasonic cleaning machine charged with the composition of the present invention [Yamato Scientific Co., Ltd., trade name: BRANSONIC220] 2
A water rinsing tank (first tank, second tank) and two water rinsing tanks (third tank, fourth tank) were prepared, and the temperature of the washing tank was set to 40°C. In addition, the temperature of the water rinsing tank was set to room temperature.

■ Apply various types of flux (manufactured by Tamura Seisakusho, product name: Flux F-2) to the item to be washed (glass epoxy printed circuit board).
30V and MH-320V) and melted solder bath (
Soldering was carried out at 260°C for 5 seconds.

■ The items to be washed were immersed in the first tank for 1 minute and then in the second tank for 1 minute to perform ultrasonic cleaning.

(2) Next, the items to be washed were sequentially immersed in the third tank and the fourth tank for 1 minute each, and the items to be washed were lightly shaken for water rinsing.

■ Finally, the items to be washed were dried in a dryer set at 110°C (drying time: 5 minutes).

■ Ion residue on the printed circuit board was measured using an omega meter.

Cleaning method in a comparative example (Figure 2) (When volatile solvent is used) ■ Three hard glass washers (1st tank, 2nd tank, 3rd tank) with a capacity of 10007 nl equipped with cooling pipes were installed. Prepare and put 300 d of comparative solvent into each tank, the first tank is a boiling tank (temperature of the boiling point of the comparative solvent), the second tank is a cooling bath (room temperature), and the third tank is a steam tank (temperature of the boiling point of the comparative solvent). And so.

(1) Each type of item to be washed was immersed in order for 1 minute (however, in the third tank, the items to be washed were simply put into the steam tank).

■ Thereafter, the ion content remaining on the printed circuit board was measured using an omega meter.

In addition, when using a high-boiling solvent in the comparative example, the "cleaning method in the example" was followed.

Examples 1-7 A cleaning experiment was conducted on the compositions shown in Table 1.

The results are shown in Table 4.

Comparative examples 1 and 2 Cleaning experiments were conducted using the solvents shown in Table 2.

The results are shown in Table 4.

Comparative example 3 Cleaning experiments were conducted using the solvents listed in Table 3.

The results are shown in Table 4.

(Hereinafter in the margins) Table 1 Table 1 (hereinafter in the margins) [Effects of the invention] The flux cleaning agent of the present invention has cleaning performance and finish quality comparable to conventional fluorocarbon-based and chlorinated solvents, and also Since it does not destroy ozone and has high biodegradability, even if it is mixed into wastewater, it can be easily decomposed by ordinary microbial treatment. Therefore, there is no fear that the water environment will be contaminated by wastewater. It is also a very safe cleaning solvent due to its low toxicity and high flash point.

Therefore, the flux cleaning agent of the present invention is practically an excellent flux cleaning agent that can replace conventional fluorocarbon-based and chlorinated solvents.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a method of cleaning an object to be washed using a cleaning agent of an example, and FIG. 2 is a schematic diagram of a method of cleaning an object to be washed using a volatile solvent of a comparative example. Patent applicant Asahi Kasei Industries, Ltd.

Claims (2)

[Claims] 1. (1) Nonionic surfactant, and (2) A flux cleaning agent characterized by containing dimethyl adipate as an essential component.