1.
No-clean solder wire is a kind of solder wire. After the no-clean solder wire is soldered, the residue is not only very small, but almost no need to be cleaned.
2. Some of the flux of ordinary solder wire contains hydrochloric acid, which is easy to corrode the welding components such as circuit boards and pins, so it is troublesome and unsafe to clean the soldered places after welding.
When using no-clean flux, the soldering process is also mainly a cleaning process, or more precisely a neutralization process. Heat energy released during soldering dissipates and neutralizes no-clean flux residues. Solder residues may not be neutralized if the no-clean flux is not sufficiently exposed to peak solder temperatures. This means that untreated raw flux is left on the PCA, and at certain temperatures and humidity, this residue is detrimental.
Flux residues are divided into harmful residues (high risk) and bad residues (low risk):
Harmful residues, in the molten state, the molecules of ions form positively and negatively charged particles (ions), polar molecules have a dipole moment, which is to say the center of the positively and negatively charged particles (polar ) at different times, some polar molecules, when exposed to certain solvents, will decompose to form ions. Ionic and polar molecular remnants are a concern because they can cause leakage between two conductors, insulation failure, severe corrosion and dendrite growth. So these will affect the functionality and reliability of the PCA.
There are also bad residues, which mainly affect the poor connection of electrical plug-ins, and may also attract dust, and even cause ions and extreme pollution. In addition, there are low-risk residues and medium-risk residues.
The no-clean flux used for manual soldering is classified as a high-risk residue because an excess of liquid flux is applied to the solder joint and spreads to a larger area. Hand soldering tools only heat locally, which means that most of the flux residue does not reach the peak soldering temperature. In manual soldering, local cleaning is recommended.