JPH03799A - Aqueous detergent composition for flux - Google Patents

Abstract

PURPOSE:To obtain the title composition having detergency at least equal to that of a fluorohydrocarbon compound without using said compound by using a diazabicyclo compound as a constituent. CONSTITUTION:The title composition contains at least one diazabicyclo compound preferably selected from among 1,4-diazabicyclo(2,2,2)octane, 1,5- diazabicyclo(4,3,0)nonane-5, and 1,8-diazabicyclo(5,4,0)undecane-7.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a flux cleaning agent for removing flux residue adhering to wiring boards after soldering, which is particularly a cause of depletion of the earth's ozone layer. The present invention relates to an epoch-making flux cleaning agent that does not use a fluorine-based hydrocarbon compound (hereinafter abbreviated as ``Freon J'') and has a cleaning power comparable to or greater than that of fluorocarbons.

Conventional technology Conventionally, flow-type automatic soldering equipment uses flux to apply flux to the surface of the wiring board prior to preheating, preheating, and then soldering to molten solder. Soldering was performed with the surfaces in contact, but since soldering leaves a considerable amount of flux residue on the surfaces, this flux residue must be removed.
Rosin-based flux is usually used, but
Conventionally, a fluorocarbon-based flux cleaning agent has been used in most cases to remove the rosin-based flux. Freon for flux cleaning is trifluorotrichloroethane (
Based on Freon-113), it has been mainly used either alone or in combination with ethanol as an azeotropic mixture, but it is non-flammable, has low toxicity, and has an excellent ability to dissolve flux well. It is known as having properties.

On the other hand, CFCs are expensive, and they also reach the ozone layer, which is located outside the Earth's atmosphere and acts as a barrier to create a calm atmosphere by absorbing the intense ultraviolet rays that fall on the Earth from space, destroying it. It has recently become clear that chlorofluorocarbons are a major problem worldwide, and it is well known that a complete ban on the use of fluorocarbons is in progress.

Therefore, there is an urgent need to develop a flux cleaning agent to replace CFCs, but for the time being, 1-1-1-) A proposal to use a fluorine-free chlorine solvent based on 1-1-1-) Lichloroethane; There have also been proposals to use oil (Bioac LEC-7), which is an extract from citrus fruits, but all of these have performance that surpasses CFCs in terms of cleaning power and safety. There is no flux cleaning agent that can replace Freon at present.

Purpose The present invention has been made in order to eliminate the drawbacks of the prior art described above, and its purpose is to have a cleaning power comparable to or better than that of Freon, and also to have fire safety. An object of the present invention is to provide an epoch-making flux cleaning agent that can excellently replace Freon.

Structure In short, the flux cleaning composition of the present invention (claim 1) is characterized in that it contains a diaza-bicyclo compound.

Further, the flux cleaning composition of the present invention (claim 2) comprises 1
．． 4-Diazabicyclo(2,2,2)octane, 1,
5-Diazabicyclo(4,3゜0)nonane-5 and 1
．． 8-Diazabicyclo(5,4,O)undecane-7
It is characterized by containing a diaza-bicyclo compound consisting of one type selected from the group of , or a mixture thereof.

The inventors of the present application have conducted intensive research to develop a flux cleaning agent that can replace Freon, and have found that it is best to use an aqueous solution or an aqueous solution containing a strongly basic diaza-bicyclo compound as a flux cleaning agent. This has led to the present invention.

It has been known that rosin, a component of flux, reacts with inorganic alkalis such as caustic soda (NaOH) and lime water to produce rosin soap, which dissolves in water. Such inorganic alkaline substances were not used for cleaning. The reason for this is thought to be that if inorganic alkali remains on the surface of the wiring board or the surface of the electronic component, the reliability of the wiring board may deteriorate.

Therefore, the inventors of the present application searched for organic alkalis that can be used as flux cleaning agents, avoiding inorganic alkalis that are thought to cause reliability problems.

As a result, it was discovered that among organic alkalis, strong basic diaza-bicyclo compounds are effective in removing rosin-based flux residues, while aliphatic amines and the like are ineffective, leading to the completion of the present invention. .

As a strong basic diaza-bicyclo compound, 1.4
-Diazerbicyclo(2,2,2)octane, 1.5-
Diazarbicyclo(4,3,0)nonane-5,1,8-
Three types of diazerbicyclo(5,4,0)undecane-7 are commercially available, and any of them can be used in the present invention.

These diaza-bicyclo compounds are used as flux cleaning agents by being dissolved in water or a mixture of water and a soluble lower alcohol in a range of 0.5 to 10%.

Here, the lower limit of the concentration of the diaza-bicyclo compound (0,5
%) is because if the concentration is lower than this, a sufficient cleaning effect cannot be obtained within the practical cleaning time (about 10 minutes) even if the cleaning concentration is increased. The upper limit (10%) was determined because these compounds are expensive, and if the concentration is too high, it would be uneconomical and the detergency would become saturated.

As the water-soluble lower alcohol, methanol, ethanol, propatool, etc. are preferable, and the mixing ratio of this and water is arbitrary, but care must be taken because if the alcohol content increases, flammability problems will occur.

Incidentally, in order to lower the surface tension and improve the wettability of the aqueous flux cleaning agent containing the diaza-bicyclo compound, it is also possible to blend a surfactant.

This surfactant, when added to an aqueous solution of a diaza-bicyclo compound, must meet two requirements: alkali resistance and a reduction in surface tension. Therefore, in the present invention, for example, the following is used.

Fluorine-containing surfactants such as perfluoroalkyl sulfone ML perfluorocarboxylate, perfluoroalkyl phosphate, perfluoroalkyl polyoxyethylene ethanol, fluorinated alkyl ester, perfluoroalkyl betaine, or (CH, CH20 ) L H [R-N-(CH,CH,O). H co 0 ・
Alkyltrioxyethylene ammonium hydroxide, etc., represented by OH (cHz CHz o) lI H.

According to this flux cleaning agent, due to the action of surfactants, conventionally used methanol, isopropyl alcohol (IPA) or trifluorotrichloroethane (
It was found that the surface tension was comparable to that of cleaning liquids such as Freon-113), and that it exhibited extremely excellent cleaning power. It has also been found that by adding a surfactant to an aqueous solution containing a diaza-bicyclo compound, the wettability between the object to be cleaned and the cleaning liquid is improved, and the ability of the cleaning liquid to penetrate into narrow gaps is improved.

Effects As described above, the present invention has the effect of providing an innovative flux cleaning agent that has a cleaning power as good as or better than that of Freon, has excellent fire safety, and can replace Freon.

Example 1 A commercially available rosin flux (Speedy Flux AGF-200-J 3, manufactured by Asahi Chemical Research Institute) was applied to a printed wiring board, and after preheating, soldering was performed at 260°C for 5 seconds. This was immersed for 1 minute in each of the various cleaning solutions shown in Table 1, washed with water, dried, and visually evaluated for cleaning properties of Franks residue.

The cleaning rate by visual inspection is 100% (◎), which is the best, and 9, which is good.
5-99% (O), effective 90-94% (Δ), defective 50-89% (×), and worst 50% or less (XX)
The results are shown in Table 1 along with comparative examples.

In Table 1, each compound is as follows.

Compound (1): l,8-diazabicyclo (5°4.0
) undecane-7 Compound (II): 1,5-diazabicyclo(4゜3
．． 0) Nonane-5 Compound (III) 71. 4-Diazerbicyclo(
2゜2.2) Octane Example 2 2 g of 1,8-diazabicyclo(5,4,O)undecane-7 was dissolved in 98 g of the following aqueous solution to prepare a flux cleaning agent.

(1) Water (2) Water/methanol - 70/30 (3) Fluorosurfactant (Surflon S-121, perfluoroalkyl quaternary ammonium salt, Asahi Glass product) (30% aqueous solution) Aqueous solution containing 0.3% Using these, a cleaning test similar to that in Example 1 was conducted (however, the cleaning liquid temperature was 20°C and the time was 1 minute).
In both cases, the cleaning rate was the best, 100%.

Claims (1)

[Scope of Claims] 1. An aqueous flux cleaning composition characterized by containing a diazabicyclo compound. 2 1,4-diazabicyclo(2,2,2)octane, 1,5-diazabicyclo(4,3,0)nonane-5
and 1.8-diazabicyclo(5,4,0)undecane-7, or a mixture thereof. .