1. Water cleaning technology
As the future development direction of water cleaning technology, it is necessary to set up pure water source and discharge water treatment workshop. It uses water as the cleaning medium, and adds surfactants, additives, corrosion inhibitors, chelating agents, etc. to the water to form a series of water-based cleaning agents. Can remove non-polar contaminants and water solvents. The characteristics of the cleaning process are:
1) Good safety, non-burning, basically non-toxic;
2) The formulation of the cleaning agent has a large degree of freedom, a wide cleaning range, and it is easy to clean both polar and non-polar pollutants;
3) Multiple cleaning mechanisms. Water is a very polar solvent. In addition to dissolving, it also has saponification, displacement, and dispersion. The use of ultrasound is much more effective than in organic solvents;
4) As a natural solvent, its price is relatively low and its sources are wide.
1) In areas where water resources are scarce, because this cleaning method consumes a lot of water resources, it is limited by the local natural conditions;
2) Departmental components cannot be cleaned with water, and metal parts are easily rusted;
3) The surface tension is large, it is difficult to clean the small gaps, and it is difficult to completely remove the residual surfactant;
4) It is difficult to dry and consumes a lot of energy;
5) The cost of the equipment is high, a wastewater treatment device is required, and the equipment occupies a large area.
2. Semi-aqueous cleaning technology
Semi-aqueous cleaning mainly uses deionized water and organic solvents, and then adds a cleaning agent composed of some appropriate active agents and additives. This type of cleaning is between solvent cleaning and water cleaning. These cleaning agents are all organic solvents and are flammable solvents with relatively high ignition point and relatively low toxicity. The characteristics of the semi-aqueous cleaning process are:
1) The cleaning ability is relatively strong, which can remove polar and non-polar pollutants at the same time, and the cleaning ability is strong;
2) Two different types of media are used for cleaning and rinsing, and pure water is generally used for rinsing;
3) Dry after rinsing.
The disadvantage of this technology is that the treatment of waste liquid and wastewater is a relatively complicated problem that has yet to be completely solved.
3. Solvent cleaning technology
Solvent cleaning mainly uses the solvent's solvency to remove contaminants. Solvent cleaning is used, because it evaporates quickly and has a strong dissolving ability, so the requirements for the equipment are very simple. And his cleaning agent can also be divided into flammable cleaning agent and non-flammable cleaning agent, flammable cleaning agent mainly includes organic hydrocarbons and alcohols (such as organic hydrocarbons, alcohols, glycol esters, etc.), non-flammable The properties mainly include chlorinated hydrocarbons and fluorinated hydrocarbons (such as HCFC and HFC).
HCFC cleaning agent and its cleaning process characteristics:
This is a hydrogen-containing chlorofluorocarbon with low latent heat of evaporation and good volatility. It is easily decomposed in the atmosphere and has a relatively small effect on destroying the ozone layer. It is a transitional product and is scheduled to be phased out before 2040. Recommended Use.
Chlorinated hydrocarbons such as dichloromethane and trichloroethane are also non-ODS cleaning agents. The characteristics of the cleaning process are:
1) The ability to clean grease and dirt is particularly strong;
2) Like the ODS cleaning agent, it can also be washed with steam and dried in the gas phase;
3) The cleaning agent does not burn or explode, and is safe to use;
4) The cleaning agent can be distilled and recycled and used repeatedly, which is more economical;
5) The cleaning process is also the same as the ODS cleaning agent.
However, its shortcomings are that the toxicity of chlorinated hydrocarbons is relatively high, and safety issues in the workplace should be paid special attention; the second is that the compatibility of chlorinated hydrocarbons with general plastics and rubber is poor; the third is that chlorinated hydrocarbons are not disorderly. The above is relatively poor, so you must add no messy agent when using it.
Hydrocarbons are hydrocarbons. In the past, gasoline and kerosene obtained by distilling crude oil were used as cleaning agents. With the increase of carbon number, the flash point of hydrocarbons increases, which increases safety, but the dryness is not good; the dryness is good, and it is not safe to use, so the two are very contradictory. Of course, as the cleaning agent, a cleaning agent with good fire safety and high flash point should be used as much as possible. The characteristics of the cleaning process are:
1) It has strong cleaning ability for grease and dirt, strong long-lasting cleaning ability, and low surface tension, which has a good cleaning effect on crevices and pores;
2) Does not corrode metals;
3) It can be distilled and recycled and used repeatedly, which is more economical;
4) Low toxicity and less environmental pollution;
5) The same medium can be used for cleaning and rinsing, which is convenient to use.
The most important of the shortcomings of the hydrocarbon cleaning process is the problem of safety, which requires strict safety methods and measures.
Characteristics of alcohol cleaning process:
Among the alcohols, ethanol and isopropanol are organic polar solvents commonly used in the industry. Methanol is more toxic and is generally only used as an additive. The characteristics of the alcohol cleaning process are:
1) It has a good dissolving ability for ionic pollutants, and the cleaning effect of rosin flux is very good, and the dissolving ability for oils is weak;
2) It has good compatibility with metal materials and plastics, and does not produce erosion and swelling;
3) Fast drying, easy to dry or air drying, no need to use hot air;
4) It has good dehydration properties and is often used as a dehydrating agent.
The main problem of alcohol cleaning agents is high volatility, low flash point, and easy combustion. It is necessary to take explosion-proof measures for cleaning equipment and auxiliary equipment.
4. No-cleaning technology
No-clean flux or no-clean solder paste is used in the soldering process. After soldering, it will go directly to the next process and no longer be cleaned. No-clean technology is currently the most commonly used alternative technology, especially mobile communication products. Wash method to replace ODS. At present, many kinds of no-clean fluxes have been developed at home and abroad. No-clean fluxes can be roughly divided into three categories:
1) Rosin type flux: Inert rosin solder (RMA) is used for reflow soldering, which can be free of cleaning.
2) Water-soluble flux: clean with water after welding.
3) Low solid content flux: no cleaning.
No-clean technology has the advantages of simplifying the process flow, saving manufacturing costs and reducing pollution. In the past ten years, the widespread use of no-clean soldering technology, no-clean flux and no-clean solder paste is a major feature of the electronics industry at the end of the 20th century. The ultimate way to replace CFCs is to achieve no-clean.
The above four cleaning methods have their own advantages and disadvantages. I like that you can choose the method according to your actual situation.