JPH05175641A - Cleaning method for board - Google Patents

Abstract

PURPOSE:To rapidly conduct the step of heating to dry subsequently to the step of rinsing a board after flux of the board is cleaned to be removed and to obtain the board having excellent cleaning degree by using rosin solder flux cleanser of special nonhalogen and special volatile rinsing agent. CONSTITUTION:Rosin solder flux cleanser of nonhalogen containing at least one type of effective ingredient of glycol ether compounds represented by a formula [R<1> is hydrogen atom or 1-5C alkyl group, R<2> is 1-5C alkyl group, R<3> is hydrogen atom or methyl group, k is integer of 2-4] is brought into contact with a board adhered with rosin solder flux, and the flux is cleaned to be removed from the board. Then, lower alcohol or its aqueous solution or lower alkyl ether is brought into contact with it as rinsing agent. According to this cleaning method, the cleanser can be completely removed from the cleaned board to obtain the board having a high cleaning degree.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of cleaning a substrate using a specific halogen-free rosin-based solder flux cleaner and a specific volatile rinse agent.

[0002]

2. Description of the Related Art Rosin-based solder flux is used for soldering in the production of modules such as printed circuit boards and printed wiring boards. After the soldering is finished, only the flux is selectively removed from the board surface by a cleaning agent. Moreover, it is completely removed. That is, when the cleaning of the flux is insufficient, there is a disadvantage that the corrosion of the circuit occurs as the adverse effect of the residual flux, or the electrical insulating property of the substrate surface deteriorates, and eventually the circuit is damaged.

Conventionally, halogenated hydrocarbon solvents such as so-called CFCs such as trichloroethylene and trichlorotrifluoroethane have been used as cleaning agents for the rosin-based solder flux. Although the halogen-based cleaning agent has the advantage that it is non-flammable and has excellent drying property, its use regulations are becoming full-scale due to the problem of environmental pollution such as ozone layer depletion. Even in Japan, there is an urgent need to develop a cleaning agent for solder flux that replaces CFCs.

Under these circumstances, various halogen-free solder flux cleaners such as saponification type, hydrocarbon solvent type, terpene solvent type, higher alcohol type and glycol ether type have recently been developed. These various CFC substitute cleaning agents require a water rinsing step and a drying step associated with the water rinsing step in order to obtain an object to be cleaned having an excellent cleanliness after cleaning and removing the flux. Here, the processing time of the drying step is rate-determining in the substrate cleaning processing system, and the longer the drying time, the lower the productivity. Therefore, the drying step is usually performed under heating at about 80 ° C. so that productivity is not lowered.

By the way, the printed circuit board and the printed wiring board obtained by washing and removing the solder flux as described above are attached with post-installed parts such as connectors and switches at the final check stage of manufacturing, and the It has been tested for operation. Since these post-installed parts are soldered in the same manner as the above-mentioned board, it is necessary to wash and remove the solder flux. However, since the post-installed parts are already attached to the printed circuit board or the printed wiring board, they are heated and dried at about 80 ° C. A water rinsing process involving a process cannot be adopted. Further, in the operation test, when it is found that a part of the component has a defect, only the component is removed, and a normal component is newly soldered to modify the board. The modified substrate thus obtained also needs to be cleaned with solder flux, and similarly, the water rinsing step involving the heating and drying step cannot be adopted.

[0006]

SUMMARY OF THE INVENTION The present invention uses a non-halogen type rosin-based solder flux cleaner, which is a novel cleaner that replaces CFCs, and heats the substrate after the rinse step after cleaning and removing the flux. It is an object of the present invention to provide a method for cleaning a substrate, which allows a drying step to be carried out quickly and a substrate having excellent cleanliness can be obtained.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that among the halogen-free rosin-based solder flux cleaners, particularly glycol ether-type cleaners are used. The present invention has been completed by finding that the above problems can be completely solved only after a substrate is washed and a specific rinsing agent is applied.

That is, according to the present invention, a substrate to which a rosin-based solder flux is attached has the general formula (1):

[0009]

[Chemical 1]

A non-halogen type rosin type solder flux detergent containing at least one glycol ether type compound represented by
The present invention relates to a method of cleaning a substrate, which comprises removing flux from the substrate by washing, and then contacting it with a lower alcohol or an aqueous solution thereof or a lower alkyl ether as a rinse agent.

The substrate used in the cleaning method of the present invention is
Examples include printed circuit boards and printed wiring boards to which rosin-based solder flux is attached. In addition, these boards were soldered once, and the solder flux was removed. When it is determined that it has occurred, the repaired board and the like obtained by removing the part and newly soldering the normal part are included.

In the present invention, a substrate such as a printed wiring board is first contacted with a non-halogen rosin-based solder flux cleaner containing at least one glycol ether compound represented by the above chemical formula 1 as an active ingredient. The flux is washed away from the substrate. Here, it is indispensable to use the glycol ether-based compound as the cleaning agent for the rosin-based solder flux. That is, hydrocarbon solvents such as tetralin, decane, dodecane,
This is because a cleaning agent using a terpene-based solvent such as limonene does not have a sufficient cleaning power, the amount of ions remaining on the substrate (residual ion concentration) is large, and it is difficult to obtain a substrate with excellent cleanliness.

Such glycol ether compounds can be used alone or in a mixture of a nonionic surfactant, a polyoxyalkylene phosphate ester surfactant, water and the like in an appropriate combination.

Examples of the glycol ether compound represented by Chemical formula 1 include diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol monopropyl ether, diethylene glycol dipropyl ether, Diethylene glycol methyl propyl ether,
Diethylene glycol ethyl propyl ether, diethylene glycol monobutyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl butyl ether, diethylene glycol ethyl butyl ether, diethylene glycol propyl butyl ether,
Diethylene glycol monopentyl ether, diethylene glycol dipentyl ether, diethylene glycol methyl pentyl ether, diethylene glycol ethyl pentyl ether, diethylene glycol propyl pentyl ether, diethylene glycol butyl pentyl ether; corresponding tri- or tetraethylene glycol ethers; -Or tetrapropylene glycol ethers can be illustrated. These compounds may be used alone or in an appropriate combination of two or more. Among these, preferred are diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, triethylene glycol dimethyl ether and the like.

The nonionic surfactant is not particularly limited as long as its ionicity is nonionic, and various known ones can be adopted. For example, polyethylene glycol ether type nonionic surfactants such as polyoxyethylene alkyl (C ₅ <) ether, polyoxyethylene phenol ether and polyoxyethylene alkylphenol ether; polyethylene glycol ester type such as polyethylene glycol monoester and polyethylene glycol diester. Nonionic surfactants; ethylene oxide adducts of higher aliphatic amines; ethylene oxide adducts of fatty acid amides; polyhydric alcohol type nonionic surfactants such as sorbitan fatty acid esters, sucrose fatty acid esters; fatty acid alkanolamides, etc. Is a polyoxypropylene nonionic surfactant and polyoxyethylene polyoxypropylene copolymer type nonionic surfactant corresponding to these. And the like. These nonionic surfactants may be used alone or in combination of two or more. Among these, polyethylene glycol ether type nonionic surfactants are preferable from the viewpoint of detergency, and those represented by the following general formula (2) are more preferable.

[0016]

[Chemical 2]

As the polyoxyalkylene phosphate ester type surfactant, various known ones can be used without limitation. Preferably, the following general formula (3):

[0018]

[Chemical 3]

The phosphoric acid ester type anionic surfactant represented by or its salt is applicable. Examples of such salts include metal salts such as sodium salts and potassium salts, ammonium salts, alkanolamine salts and the like. In addition, as the phosphoric acid ester-based anionic surfactant represented by the general formula (3) or a salt thereof, there are various commercially available products,
For example, "Prysurf" series manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., "N-1000FC" manufactured by Nippon Emulsifier Co., Ltd.
P "," RA-574 "," RA-579 ", etc. can be illustrated.

The proportion of the above-mentioned detergent to be used is usually about 10 to 100% by weight, preferably 50 to 95% by weight, of the glycol ether compound, and the nonionic surfactant and / or polyoxyphosphate ester surfactant is 0%. ~
It is about 90% by weight, preferably 5 to 50% by weight.
When the cleaning agent is used by dissolving it in water, the concentration of the active ingredient is usually adjusted to about 10% by weight or more, preferably 50% by weight or more.

The following means can be adopted to bring the cleaning agent into contact with the rosin flux on the substrate. For example, a method of cleaning with a hand brush, a method of cleaning with a roll brush, a method of directly immersing the substrate in the cleaning agent itself, a method of flushing the cleaning agent with a spray device, and a method of brushing with a mechanical means. Various methods such as an ultrasonic cleaning method and a method of supplying a cleaning agent from a can as an aerosol or foam can be appropriately selected and adopted.

The conditions for applying the detergent may be appropriately selected depending on the concentration of the active ingredient in the detergent, the usage ratio of the ingredient, the type of flux to be removed, and the like. Generally, the flux to be removed is washed. Contact the cleaning agent with the flux at a temperature and for a time effective to remove it. The temperature at the time of using the cleaning agent is usually room temperature to 80 ° C.
It is preferable to set the temperature to about ° C. Especially when applied to a modified substrate or the like, the temperature is preferably from room temperature to about 50 ° C.

In the present invention, after removing the rosin-based solder flux from the substrate by the non-halogen-based cleaning agent as described above, lower alcohol or its aqueous solution or lower alkyl ether is further contacted as a rinse agent. Such a rinse agent can completely remove the non-halogen type cleaning agent which may remain.
Further, it has excellent drying property, and the drying time can be shortened.

Examples of the lower alcohol include alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propanol, iso-propanol and n-butanol. Further, the lower alcohol may be used as an aqueous solution, and usually, it can be used as an aqueous solution having a concentration of about 5% by weight or more, preferably a concentration of 30% by weight or more. Further, examples of the lower alkyl ether include diethylene glycol dimethyl ether, diethylene glycol diethyl ether, ethyl ether and the like. Of these, a lower alcohol aqueous solution having a concentration of 30 to less than 60% by weight is preferable from the viewpoint of volatility and safety.

The conditions for using the rinsing agent include a method of directly immersing the substrate in the rinsing agent, a method of flushing the rinsing agent with a spray device, a method of irradiating ultrasonic waves, and a method of using vapor of the rinsing agent. The rinsing treatment can be effectively performed by adopting at least one of the methods of supplying from a can as aerosol, foam, and the like. The temperature when using the rinse agent is usually from room temperature to about 50 ° C. Further, the temperature of the drying step following the rinsing step is usually about room temperature to 50 ° C., and the drying time is relatively short.

In addition to the case of using a single rinsing tank in the rinsing process, a plurality of rinsing tanks can be used, and the specifications are appropriately determined in consideration of the processing cost, the processing time, the life of the rinsing solution, etc. All you need to do is It is also possible to wash with water before using the rinsing agent and then drain with the rinsing agent.

[0027]

According to the cleaning method of the present invention, the cleaning agent can be completely removed from the substrate cleaned with the non-halogen type cleaning agent, and a substrate having a very high cleanliness can be obtained. Moreover, due to the volatility of the rinse agent, the time required for the drying step is extremely reduced, and further, the drying can be performed even at room temperature, the workability is greatly improved, and the productivity is improved. The effect of. In particular, the present invention is advantageous in that it can be dried even at room temperature when it is applied to a modified substrate to which a retrofit component is attached.

[0028]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Reference Example 1 65 parts by weight of diethylene glycol dimethyl ether and a nonionic surfactant of polyethylene glycol alkyl ether type (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name "Neugen ET-135", R ⁴ in the general formula (2) is carbon. Number 1
2 to 14 branched chain alkyl groups, m is 9) 2
A cleaning agent A was prepared by mixing 0 part by weight and 15 parts by weight of pure water.

Reference Examples 2 to 6 Detergents A to F were prepared in the same manner as in Reference Example 1 except that the composition of the detergent was changed as shown in Table 1.

Reference Examples 7 to 9 As in Reference Example 1, a rinse agent G having the composition shown in Table 2 was used.
~ I was prepared.

[0032]

[Table 1]

[0033]

[Table 2]

In Tables 1 and 2, DEGDME: diethylene glycol dimethyl ether, DEGMBE: diethylene glycol monobutyl ether, TEGDE:
Triethylene glycol diethyl ether, POEAP
E: Phosphate ester type anionic surfactant (in the general formula (3), R ⁵ is a linear alkyl group having 12 carbon atoms, n
Is 10, X is a hydroxyl group, and general formula (4): (R ⁶ has 1 carbon atom
2 is a linear alkyl group, and n is a mixture of 10)).

Example 1 A rosin-based flux (trade name "Resin Fl" manufactured by LONCO Co., Ltd.) was formed on the entire surface of a printed wiring board (copper clad laminate).
ux # 77-25 ″), dried at 130 ° C. for 2 minutes, and then solder-flowed at 260 ° C. for 5 seconds to prepare a test substrate. The cleaning agent A was applied at room temperature and rubbed with a solder brush. This was repeated twice and then rinsed with the rinse agent G at room temperature to rinse the remaining cleaning agent on the substrate. Furthermore, this substrate was dried at room temperature or under a temperature condition of 40 ° C., and the time required for drying was measured. Further, the degree of flux removal of the obtained substrate was visually determined based on the following criteria. ◯: Can be removed well. Δ: Some remains. X: Remains considerably. Then, the above substrate is attached to the Omega meter 600SE (KEN
The cleanliness (residual ion concentration) of the substrate was measured by using KO, trade name. The results are shown in Table 3.

Examples 2 to 15 Evaluations were made in the same manner as in Example 1 except that the types of cleaning agents and rinsing agents were changed to those shown in Table 3. The results are shown in Table 3.

Example 16 In Example 1, 90 parts of detergent A and 10 parts of carbon dioxide gas were used.
Part aerosol cans were filled and sealed to be used as an aerosol type, 90 parts of rinse agent I and 10 parts carbon dioxide gas were filled and sealed in an aerosol can to be used as an aerosol type. evaluated. The results are shown in Table 3.

Comparative Example 1 Example 1 is the same as Example 1 except that water is used as the rinse agent.
I went the same way. The results are shown in Table 3.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the cleaning agent and the rinsing agent in Example 1 were replaced with Freon 113. The results are shown in Table 3.

Comparative Example 3 The same procedure as in Example 7 was carried out except that the cleaning agent in Example 1 was replaced with limonene. The results are shown in Table 3.

[0041]

[Table 3]

Claims (3)

[Claims] 1. A substrate represented by the general formula (1): A non-halogen rosin-based solder flux cleaner containing at least one glycol ether compound represented by as an active ingredient is contacted, the flux is washed off from the substrate, and then a lower alcohol or its rinse is used as a rinse agent. A method of cleaning a substrate, which comprises contacting with an aqueous solution or a lower alkyl ether. 2. The cleaning treatment method according to claim 1, wherein the rinse agent is a lower alcohol or an aqueous solution thereof. 3. The cleaning method according to claim 1, wherein the substrate is a substrate obtained by soldering and removing a rosin-based solder flux, and a retrofit component attached to the substrate.