When troubleshooting non-functional or poor performance circuits, engineers can run simulations or other analysis tools to consider the circuit from the schematic level. If these methods can not solve the problem, even the best engineers may be stumped and frustrated or confused. To avoid a similar dead end, I’ll introduce you to a simple but very important tip: Keep PCB clean.
The surface cleanliness of printed boards is also known as ionic contamination. Cleanliness directly affects the surface insulation resistance of PCB and longlife of PCB.
Poor cleanliness and serious pollution of the ion will cause the weldability and surface insulation resistance of PCB to decrease. In wet environment,conductors will also cause corrosion and affect the life of printed boards.
Especially for the high density wiring board with small wire and small spacing, the effect is more obvious, so it must be cleaned strictly before and after the coating of the printed board to meet the cleanliness requirements.
Cleanliness is to clean the surface of the printed board of the unprinted solder mask film by chemical extraction (usually using isopropanol water extract with a resistivity greater than 6Mg2cm). The resistivity of the extracted solution should be greater than 2MQcm, or equivalent to 156ugcm2 sodium chloride equivalent. We should pay attention to the cleaning and operation of the environment in order to prevent the second time pollution from affecting the results of the determination.
Some materials used during PCB assembly or modification can cause serious circuit functional problems if the PCB is not properly cleaned. One of the most common problems in this type of phenomenon is flux.
Flux is a chemical used to help solder components to the PCB. Unfortunately, if it is not removed after soldering, the flux will deteriorate the surface insulation resistance of the PCB, which will seriously degrade the circuit performance in the process.