Solvent cleaning technology for PCB board
Solvent cleaning is mainly the use of solvent solubility to remove pollutants. Using solvent cleaning, because of its rapid volatilization, strong dissolution ability, so the equipment requirements are simple. According to the choice of cleaning agent, can be divided into flammable cleaning agent and incombustible cleaning agent, the former mainly includes organic hydrocarbons and alcohols (such as organic hydrocarbons, alcohols, diol esters, etc.), the latter mainly includes chlorine hydrocarbons and fluorinated hydrocarbons (such as HCFC and HFC) and so on.
HCFC cleaning agent and its cleaning process characteristics
This is a kind of hydrogen-containing chlorofluorocarbon, which has low latent heat of evaporation, good volatility, easy decomposition in the atmosphere, damage to the ozone layer is relatively small, is a transitional product, stipulated before 2040, so we do not recommend the use of this kind of cleaning agent.
There are two main problems: one is transitional. It will only be allowed until 2040 because of its damaging effect on the ozone layer. Second, the price is relatively high, the cleaning ability is weak, increased the cleaning cost.
Characteristics of cleaning process for chlorinated hydrocarbons
Chlorinated hydrocarbons such as dichloromethane and trichloroethane are also non-ods cleaners. The cleaning process features are:
(1) the ability to clean grease and dirt is particularly strong;
(2) like ODS cleaning agent, steam can also be used to wash and dry the gas phase;
(3) cleaning agent does not burn, do not explode, safe use;
(4) cleaning agent can be recovered by distillation, repeated use, relatively economical;
(5) the cleaning process is the same as the ODS cleaning agent.
However, the disadvantages of the first is that chlorinated hydrocarbons are relatively toxic, workplace safety needs special attention; Secondly, the compatibility of chlorinated hydrocarbons with general plastics and rubber is poor. Third, chlorinated hydrocarbons in the stability of the poor, use must be added stabilizer.
Characteristics of hydrocarbon cleaning process
Hydrocarbons, or hydrocarbons, used to be gasoline and kerosene made by distilling crude oil as cleaning agents. The flash point of hydrocarbons increases with the increase of carbon number, which increases the safety. Dry good, use is not too safe, so the two are very contradictory. Of course, as a cleaning agent should try to choose a good fire safety, flash point higher cleaning agent. The cleaning process features are:
(1) strong cleaning ability for grease and grease filth, persistent cleaning ability, low surface tension, good cleaning effect for small cracks and pores;
(2) non-corrosive to metal;
(3) it can be recovered by distillation and used repeatedly, which is relatively 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 shortcomings of hydrocarbon cleaning process, the most important is the safety problem, there must be strict safety methods and measures.
Characteristics of alcohol cleaning process
Ethanol and isopropanol in alcohol are commonly used in industry organic polar solvents, methanol toxicity is greater, generally only as additives. The characteristics of alcohol cleaning process are:
(1) good dissolving ability for ionic pollutants, very good cleaning effect for rosin flux, weak dissolving ability for grease;
(2) good compatibility with metal materials and plastics, without corrosion and expansion;
(3) fast drying, easy to dry or air drying, do not need to use hot air;
(4) good dehydrating ability, commonly used as dehydrating agent.
The main problem of alcohol cleaning agent is high volatility, low flash point, easy to burn, it is necessary to take anti-explosion measures for cleaning equipment and auxiliary equipment.
The above summary of a new generation of circuit board cleaning technology hope to help you.