PCB Board Cleaning Technology


Release time:

2020-03-10

PCB cleaning technology for PCB, has a very important position. Because it is necessary to ensure the cleanliness of the circuit board itself in order to accurately scan and generate file maps, the cleaning technology of the circuit board has also become an important "technical activity". Ruibao's own engineers have mainly summarized the current technology. Four ways of a new generation of circuit board cleaning technology.

1. Water cleaning technology for PCB copying

Water cleaning technology is the development direction of cleaning technology in the future, and pure water source and discharge water treatment workshop must be set up. It uses water as a cleaning medium, and adds surfactants, additives, corrosion inhibitors, chelating agents, etc. to form a series of water-based cleaning agents. Water solvents and non-polar contaminants can be removed.

Its cleaning process is characterized:

(1) Good safety, no combustion, no explosion, basically non-toxic;

(2) The formula of the cleaning agent has a large degree of freedom, and it is easy to clean the polar and non-polar pollutants, and the cleaning range is wide;

(3) multiple cleaning mechanism. Water is a polar solvent with strong polarity. In addition to dissolution, it also has the common effects of saponification, emulsification, replacement, 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 source is wide.

The disadvantages of water cleaning are:

(1) In areas where water resources are scarce, because the cleaning method needs to consume a large amount of water resources, it is limited by local natural conditions;

(2) Some components cannot be cleaned with water, and metal parts are easy to rust;

(3) the surface tension is large, it is difficult to clean the small gap, and it is difficult to remove the residual surfactant thoroughly;

(4) the drying is difficult and the energy consumption is large;

(5) The equipment cost is high, wastewater treatment equipment is required, and the equipment occupies a large area.

2. Half water cleaning technology of PCB copying board

Semi-aqueous cleaning mainly uses organic solvents and deionized water, plus a certain amount of active agent, additives composed of cleaning agent. This type of cleaning is intermediate between solvent cleaning and water cleaning. These cleaning agents are organic solvents, flammable solvents, flash point is relatively high, toxicity is relatively low, the use of relatively safe, but must be rinsed with water, and then dried. Some cleaning agents add 5% to 20% of water and a small amount of surfactant, which not only reduces the flammability, but also makes rinsing easier. Semi-water cleaning process is characterized:

(1) The cleaning ability is relatively strong, it can remove polar pollutants and non-polar pollutants at the same time, and the cleaning ability is persistent;

(2) Cleaning and rinsing use two different media, rinsing generally uses pure water;

(3) dry after rinsing.

The disadvantage of this technology is that waste liquid and wastewater treatment is a relatively complex and yet to be completely solved.

3. No-cleaning technology for PCB copy board

In the welding process using cleaning-free flux or cleaning-free solder paste, welding directly into the next process is no longer cleaning, cleaning-free technology is currently the most used alternative technology, especially mobile communication products are basically used to replace ODS. At present, many kinds of free flux have been developed at home and abroad, such as Beijing Jingying company's free flux. No-clean fluxes can be broadly divided into three categories:

(1) Rosin flux: Re-flow soldering uses inert rosin solder (RMA), which can be washed free.

(2) Water-soluble flux: clean with water after welding.

(3) low solid content flux: no cleaning.

The non-cleaning technology has the advantages of simplifying the process, saving the manufacturing cost and less pollution. In the past ten years, the widespread use of no-clean welding 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 cleaning.

 

4. Solvent cleaning technology for PCB copying

 

Solvent cleaning is mainly the use of the solvent dissolving power to remove contaminants. The use of solvent cleaning, because of its volatile fast, strong solubility, so the equipment requirements are simple. According to the choice of cleaning agent, can be divided into flammabilityCleaning agentand non-flammabilityCleaning agentThe former mainly includes organic hydrocarbons and alcohols (such as organic hydrocarbons, alcohols, glycol esters, etc.), while the latter mainly includes chlorinated hydrocarbons and fluorinated hydrocarbons (such as HCFC and HFC).

 

HCFC cleaning agent and its cleaning process characteristics

This is a kind of hydrogen-containing chlorofluorocarbon, its evaporation latent heat is small, good volatility, easy to decompose in the atmosphere, the role of destroying the ozone layer is relatively small, belongs to a transitional product, provisions in 2040 before the phase-out, so we do not recommend the use of this typecircuit board cleaning agent.

There are two main problems: one is the transition. Because it has a destructive effect on the ozone layer, it is only allowed to be used until 2040; second, the price is relatively high, the cleaning capacity is weak, and the cleaning cost is increased.