JP3298294B2 - Method for cleaning electronic material having microporous structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning electronic materials having a fine pore structure. More specifically, before dirt such as oils and fats, rosin-based flux, etc. attached to an electronic material having a microporous structure is cleaned using a non-halogen-based cleaning agent, the pores of the microporous structure of the electronic material are removed. The present invention relates to a method for cleaning an electronic material having a microporous structure, which is protected by using an inert liquid.

[0002]

2. Description of the Related Art Conventionally, dirt such as oils and fats and flux adhering to electronic materials such as printed circuit boards has various adverse effects such as poor adhesion, circuit corrosion, and insulation failure in each application. The agent has been washed away from the object to be washed.

[0003] As a cleaning agent used for such cleaning, halogenated hydrocarbon solvents such as so-called chlorofluorocarbon such as trichloroethane, methylene chloride and trichlorotrifluoroethane have been used. Although the halogen-based cleaning agent itself has the advantage of being nonflammable and excellent in drying property, it cannot be used due to environmental pollution problems such as destruction of the ozone layer and toxicity. Under such circumstances, an aqueous detergent comprising a mixture of a hydrocarbon solvent, a glycol ether compound, various surfactants, water and the like has recently been used as a non-halogen detergent.

[0004] By the way, these various non-halogen-based detergents are hardly volatile because of problems of toxicity and flammability. After the cleaning process, a water rinsing process is continuously performed as a rinsing process.

However, when the object to be cleaned is an electronic material having a microporous structure, such as a printed circuit board to which a cable using porous polyethylene or the like as an insulating material is connected, the micropores in the cleaning step. The pores of the structure are impregnated with a non-volatile cleaning agent. The non-volatile cleaning agent thus impregnated is difficult to remove in the rinsing step. Also, the pores of the microporous structure are easily impregnated with rinsing water used in the rinsing step. Therefore, the cleaning step is often completed in a state of poor drying in which the cleaning agent and the rinse water cannot be removed. Such a poorly dried object to be cleaned, even if the cleaning agent itself does not have an adverse effect, is impregnated with flux and other stains in the impregnated cleaning agent. There is a problem that causes.

In order to solve such a problem, a cleaning agent which does not degrade the performance such as the insulating property of the object to be cleaned is always used in a new liquid state, or volatilization is carried out with knowledge of danger such as flammability. There was no other means than washing with a highly aggressive cleaning agent.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a non-halogen-based electronic material having a microporous structure capable of efficiently removing dirt components from an object to be cleaned without deteriorating the performance such as insulating properties of the electronic material. An object of the present invention is to provide a method for cleaning an electronic material having a microporous structure using a cleaning agent.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems of the prior art. as a result,
Before cleaning dirt components from an electronic material having a microporous structure with a non-halogen-based cleaning agent, the electronic material is brought into contact with an inert liquid, and the inert liquid is passed through the pores of the microporous structure of the electronic material. If impregnated and protected, it is possible to prevent the cleaning agent and the rinsing agent from entering the holes in the subsequent process, so that the dirt components can be efficiently removed without lowering the performance of the electronic material such as the insulating property. I found that.

That is, according to the present invention, in cleaning an electronic material having a microporous structure with a cleaning agent, and cleaning and removing dirt on the electronic material, the electronic material is brought into contact with an inert liquid before the cleaning treatment. And a method of cleaning an electronic material having a microporous structure, characterized by impregnating an inert liquid into pores of the microscopic structure of the electronic material.

The electronic material having a microporous structure, which is the object to be cleaned of the present invention, is usually called an electronic material, and a microporous material in which a part of the electronic material is impregnated with a cleaning agent or the like. It has a structure. Examples of the electronic material having such a micropore structure include an electronic component in which the electronic material itself has a micropore structure, an electronic component in which the electronic component having the micropore structure is mounted as a part of the electronic material, and a micropore structure. And the like in which the non-electronic material is connected to the electronic material.

More specifically, as electronic components in which the electronic material itself has a microporous structure, there are cement resistors, variable resistors, switches such as dip switches, trimmer capacitors, IC sockets, connectors, transformers, and the like.
Examples include coils. Examples of the electronic component having the microporous structure mounted thereon as a part of the electronic material include a printed circuit board and a hybrid IC on which the electronic component such as the cement resistor is mounted. In addition, as a non-electronic material having a microporous structure connected to an electronic material, it is mounted on a printed circuit board such as a cable to which a cable using a foaming material such as polyethylene or Teflon as an insulating material is connected. Printed circuit boards, hybrid ICs, etc., on which a porous phenol resin or the like is potted to protect the bare chips.

As the inert liquid used in the present invention, even when impregnated into the fine pores of the electronic material having the fine pore structure, it is electrically neutral and has problems such as poor insulation and corrosion. That can be easily dried and removed after cleaning and removing dirt from the electronic material. As such an inert liquid, a liquid generally having a boiling point of about 20 to 150 ° C. and being incompatible with the detergent used can be used. Specific examples include various non-flammable fluorocarbons and hydrofluorocarbons.
Examples include perfluoroalkanes such as 2-methylpentane, perfluorocyclohexane, perfluoromethylcyclohexane, perfluoro-1,3-dimethylcyclohexane, and perfluoro-N-methylmorpholine. Examples of commercially available fluorocarbons include the "Fluorinert" series manufactured by Sumitomo 3M Limited.
The inert liquid to be used differs depending on the shape and properties of the electronic material having a fine pore structure, which is an object to be cleaned, and it is necessary to appropriately select the inert liquid according to the object to be cleaned.

As the cleaning agent used in the present invention, various known non-halogen cleaning agents can be used. Examples of non-halogen detergents include, for example, terpenes such as limonene, hydrocarbon solvent types such as petroleum solvents such as dodecane, higher alcohol types such as glycol ether compounds, and mixtures thereof, as well as various solvents and interfaces. Activators, mixtures with water and the like can be exemplified.

In the present invention, among the above-mentioned non-halogen-based detergents, those containing a glycol ether compound are preferable. In addition to the glycol ether compound, any one of water, a surfactant and a hydrocarbon is preferable. Mixtures containing seeds can also be used preferably. In addition, it is necessary to appropriately select the type and composition of these non-halogen-based cleaning agents depending on the shape and properties of the object to be cleaned.

As the glycol ether compound, for example, diethylene glycol monomethyl ether,
Diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol monoethyl ether acetate, 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 monobutyl ether acetate, diethylene glycol monopentyl ether, diethylene glycol dipentyl ether, diethylene glycol Methylpentyl ether, diethylene glycol ethyl pentyl ether, diethylene glycol propyl pentyl ether,
Diethylene glycol butyl pentyl ether; tri- or tetraethylene glycols corresponding thereto; di-, tri- or tetrapropylene glycols corresponding thereto.

As the surfactant, various anionic surfactants, nonionic surfactants and the like can be used.

The general steps of the cleaning method of the present invention will be described below.

In the present invention, first, an electronic material having a fine pore structure to be cleaned is brought into contact with an inert liquid,
The inert liquid is impregnated into the pores of the microporous structure of the object to be cleaned and protected. As a condition for bringing the object to be cleaned into contact with the inert liquid, generally, a method of directly immersing the object to be cleaned can be adopted. Further, depending on the shape and properties of the object to be cleaned, temperature conditions or reduced pressure conditions may be appropriately controlled, and as a mechanical method, a method of jetting the object to be cleaned in liquid, a method of flashing with a spray, A method of irradiating a sound wave or the like can be appropriately adopted. Furthermore, by preheating for about several minutes at a high temperature of about 50 to 100 ° C. before bringing the object to be cleaned into contact with the inert liquid, it is possible to impregnate the pores of the microporous structure with the inert liquid efficiently. It can be impregnated quickly even when the micropore structure is large.

Next, in the present invention, the dirt component of the object to be cleaned, whose pores of the microporous structure are protected by the inert liquid, is dissolved and dispersed by the cleaning agent. Conditions for applying the cleaning agent may be appropriately selected depending on the type of the cleaning agent, the concentration of the active ingredient in the cleaning agent, the use ratio of the component, the type of the dirt component to be removed, and the like. The washing is performed at a temperature and for a time effective to wash and remove the components. Generally, if a cleaning agent is brought into contact with an object to be cleaned at a temperature of about room temperature to about 80 ° C. for about 1 to 10 minutes, an object to be cleaned having a good cleanness can be obtained. As a contact method, a method of jetting in a liquid, a method of irradiating an ultrasonic wave,
A flash method using a spray device or the like can be adopted. In particular, when it is not desired to attach a cleaning agent to a portion other than a portion where dirt is attached, a method of flushing in the air by spraying is good, and a nozzle having high straightness is particularly effective. The above nozzle is a LECHL having a multi-orifice structure.
A multi-channel flat jet nozzle manufactured by ER GmbH + CO KG can be exemplified.

Next, the mixture of the dirt component and the cleaning agent on the surface of the object to be cleaned is completely removed by a rinsing agent.
Examples of the rinsing agent include alcohols and deionized water. In consideration of safety and the like, it is preferable to use deionized water. As conditions for applying the rinsing agent, the same conditions as those for applying the cleaning agent can be adopted. Further, the rinsed object is finally dried in the drying step together with the rinsing agent to remove the inert liquid, thereby completing the cleaning. The washing step and the rinsing step can be appropriately performed as a plurality of washing steps and a plurality of rinsing steps depending on the shape and properties of the object to be cleaned and the properties and amounts of the stain components.

[0021]

According to the cleaning method of the present invention, the following effects can be obtained.

(1) In a cleaning step and a rinsing step of an electronic material having a microporous structure, it is possible to prevent a cleaning agent or a rinsing agent from entering the pores of the microporous structure, thereby preventing poor drying of the object to be cleaned. .

(2) The impregnated inert liquid does not change the properties of the object to be cleaned and has good volatility, so that it can be easily removed by a drying step or natural drying. The performance of the electronic material as the cleaning object can be maintained for a long time. In particular, the present invention can be effectively applied to electronic components that require high insulating properties and electronic materials such as a printed circuit board having a porous insulating material.

(3) Further, since an electronic material having a fine pore structure, which has conventionally been considered to be able to be cleaned only with a safe and volatile solvent such as chlorofluorocarbon, can be cleaned with a non-halogen-based cleaning agent, the ozone layer destruction and the like can be prevented. Can also contribute to the problem of global environmental pollution.

[0025]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Comparative Examples and Examples, but the present invention is not limited to these Examples.

Comparative Example 1 70% by weight of diethylene glycol monobutyl ether
Diethylene glycol monoethyl ether acetate 2
A cleaning agent A having a composition of 5% by weight and 5% by weight of water was prepared.

The flux residue of a printed circuit board (hereinafter, referred to as a cable board) to which a cable having an expandable polyethylene insulating material is connected is heated by a cone type shower system using the cleaning agent A having the above composition. 40
It wash | cleaned on condition of 3 degreeC for 3 minutes. Next, the cable substrate was rinsed with deionized water by a cone-type spray shower method at room temperature for 3 minutes. Further, after the final rinsing was performed using deionized water under the same conditions, the substrate was dried in a hot-air circulation type drying tank at a temperature of 60 ° C. for a drying time of 15 minutes to complete the cleaning.

The above-mentioned cleaned cable substrate was evaluated according to the following method. Table 1 shows the results.

(Flux removal degree) UV lamp (36)
5 nm), and the degree of light emission by the flux residue was visually evaluated. ：: excellent removal △: slight residual ×: residual

(Evaluation of Insulation) The insulation resistance (Ω) between the insulation material and the signal line in the cable before and after cleaning was determined by measuring the cable length by 2.
Cut to 5cm, 25 ° C, 50% RH, applied voltage 500
V was measured under the conditions of an application time of 30 seconds. As a measurement model, insulation resistance measuring instrument TR-8601 (Advantes
t) was used.

Example 1 In Comparative Example 1, the cable substrate was immersed in perfluorooctane (trade name “Fluorinert FC75”, manufactured by Sumitomo 3M Ltd.) at 20 ° C. for 3 minutes before cleaning with a cleaning agent. Was evaluated by performing the same cleaning as in Comparative Example 1. Table 1 shows the results.

Examples 2 to 5 The same cleaning as in Example 1 was performed, except that the type of the cleaning agent was changed to the composition shown in Table 2, and the evaluation was performed. Table 1 shows the results.

Example 6 The same cleaning as in Example 1 was performed, except that the cable substrate was preheated at 80 ° C. for 5 minutes before the cable substrate was immersed in perfluorooctane. And evaluated. Table 1 shows the results.

Example 7 In Example 1, the cleaning method was changed to a nozzle (L
ECHLER GmbH + CO KG, product name "Multi-channel flat jet nozzle: FL-600
A)), except that the cleaning was carried out in the same manner as in Example 1, except that the evaluation was changed. Table 1 shows the results.

[0035]

[Table 1]

[0036]

[Table 2]

In Table 2, DEGMB: diethylene glycol monobutyl ether, DEGME-Ac: diethylene glycol monoethyl ether acetate, DEGD
B: diethylene glycol dibutyl ether, DEGM
P: Diethylene glycol monopentyl ether is shown.

From the results in Table 1, it can be seen that, as in Comparative Example 1, when the cleaning was performed by the cleaning method without the protective processing step using an inert liquid, the insulation between the insulating material in the cable and the signal line was reduced. Although it is recognized that the cleaning treatment method of the present invention shown in the examples is significantly reduced, the reduction is hardly recognized. Examples 6 and 7
As shown in the above, further improvement is recognized by devising the preheating method and the cleaning method, and the effectiveness of the cleaning treatment method of the present invention for an electronic component having a microporous structure is recognized. It is also recognized that the use of the non-halogen-based cleaning agent employed in the examples allows the flux residue to be efficiently removed from the object to be cleaned.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B08B 3/10 C11D 7/26 H05K 3/26

Claims (4)

(57) [Claims] An electronic material having a microporous structure is washed with a cleaning agent, and in cleaning and removing dirt on the electronic material, the electronic material is brought into contact with an inert liquid before the cleaning process. A method for cleaning an electronic material having a fine pore structure, characterized by impregnating an inert liquid into the pores of the fine pore structure. 2. The cleaning method according to claim 1, wherein the cleaning agent contains a glycol ether compound, and further contains one or more of water, a surfactant, and a hydrocarbon as needed. 3. The cleaning method according to claim 1, wherein the inert liquid is a non-flammable fluorocarbon and / or hydrofluorocarbon. 4. An electronic material having a microporous structure is heated at 50 ° C.
The cleaning method according to claim 1, wherein after preheating to a temperature of about 100C, the cleaning liquid is brought into contact with the inert liquid.