|
I keep hearing folks here mentioning water penetration
toggle quoted message
Show quoted text
of circuit board substrates, I think I can help you lay that myth firmly to rest. The process of making pcb's has always involved many long steps where the board is entirely immersed in water or water based solutions. Between each of these steps, the board is immersed in pure clean water as the etchants, and plating solutions are rinsed off of the board. One poster mentioned a board losing its high insulation value due to water washing. I think the resistance was damaged not from the water, but rather from what was in the water, and not from what soaked into the board, but rather from what was left behind on the surface of the board. Detergents come in two basic types, ionic and non ionic. Ionic based surfactants are great cleaners, but are also highly conductive of electricity. If not rinsed fully, they leave a conductive film. This film is often used to dissipate static charge from plastic surfaces, like meter windows. Also, not all water is equal. Hard waters, and acid neutralized waters, have high mineral content, which is in the form of salts. If the water is allowed to evaporate on the board, it will leave a conductive residue of a particularly nasty type: one that changes its resistance with ambient humidity. -Chuck Harris Adrian Nicol fenland787a@... [hp_agilent_equipment] wrote: I understand the desire to try and get the insides to look like new! Like Paul, I guess I have 50+ bits of oldish HP and Tek equipment, but I'm not sure I would do what you intend, especially with water! |
