How to clean lead-free solder paste after the soldering process is completed?

As we all know, after the welding process is completed,PCBThere might be some impurities remaining on it. So, how to clean it? The following solder paste manufacturer will explain it to you:

First of all, it is necessary to understand why cleaning is needed. After the soldering process of lead-free solder paste is completed, there will be more or less residual impurities, and there are several types of residual impurities:

aParticulate pollutants are prone to cause electrical short circuits.

bPolar contaminants can also cause dielectric breakdown, leakage and corrosion of electronic component circuits, etc.

cNon-polar contaminants can seriously affect the surface, usually consisting of white powder, adhering to dust, and causing poor electrical contact.

On the other hand, even though it was recognized that cleaning was necessary, the wrong cleaning methods were chosen, as follows:

AWhen ultrasound is not included, willPCBThe circuit board can be simply soaked and then taken out to dry.

BDip the brush in the cleaning agentPCBThe circuit board is brushed only a few times.

Lead-free solder pasteThe composition of residual debris is complex. Non-polar contaminants centered on rosin or other synthetic resins encapsulate halogens, organic acids, salts, etc., playing a "plastic sealing" role. As a result, the corrosion of ionic contaminants is significantly reduced, and various problems such as leakage of electricity after moisture absorption are inevitable. During the cleaning process, the resin is selectively removed. At this point, the cleaning operation is completed. If any residue remains on the circuit board, it will be ionic contamination, and the serious consequences can be seen from this. The situation caused by not cleaning in time is always more serious than that of not cleaning at all. Therefore, whenever cleaning is needed, it must be done thoroughly.

In that case, how is it usually cleaned up?

1It needs to be cleaned in a timely manner after the welding process(1Within an hour);

2Strengthen the preheating working temperature of the cleaning agent;

3Extend the cleaning time;

4Change the cleaning agent from time to time.

After cleaning, we'd better check again to see if it has really been cleaned thoroughly. The simple method is to take visual inspection and observe under a microscope.