PCB & environmental problems

[denver56]

HI! I developped an analogic filtering PCB composed by resistor, capacitors (4 of them electrolitics) and operational amplifiers. I have to put it inside an incubator whith 90% humididty, 5% CO2 and temperature 37 °C. Do you know if and how they can affect environment and vicecersa ? Do you have any scientific articles to suggest ?
THX!

 

[jiripolivka]

HI! I developped an analogic filtering PCB composed by resistor, capacitors (4 of them electrolitics) and operational amplifiers. I have to put it inside an incubator whith 90% humididty, 5% CO2 and temperature 37 °C. Do you know if and how they can affect environment and vicecersa ? Do you have any scientific articles to suggest ?
THX!

I am sure you can find manufacturing standards for such case. The rules are- use a PCB material that either does not soak water (Teflon-based laminate), or, treat it so it cannot. You can use paraffine or other wax to wet the PCB or the complete circuit (if the temperature would not go over 37 deg.C). There are varnishes named conformal coat, available in spray which are used to "weatherize" PCB circuits. They can only be applied after the wiring is complete. Difficult to remove but resisting moisture.

 

[denver56]

Notice that PCB have Silver Finishing and Copper 35 um on FR4 1,6 mm.
Do you think is still necessary coating ? If yes, the spray will be enough to coat 95% humidity ? I have bought this one :
**broken link removed**
**broken link removed**
What do you think about it ?

And should I spray it only on IC components and/or passive components and/or solder parts and/or whole PCB ? THX!

 

[jiripolivka]

Notice that PCB have Silver Finishing and Copper 35 um on FR4 1,6 mm.
Do you think is still necessary coating ? If yes, the spray will be enough to coat 95% humidity ? I have bought this one :
**broken link removed**
**broken link removed**
What do you think about it ?

And should I spray it only on IC components and/or passive components and/or solder parts and/or whole PCB ? THX!

Conformal coating should cover the whole thing including wires close to your PCB, like you could mold it into an Epoxy resin or paraffine wax. The cover prevents moisture to enter sensitive places. I do not see any point in silver plating the PCB lines. It is nicer but has nothing to do with corrosion.

 

[denver56]

one other information : the pcb has 30 gold pins spaced 5 mm one each other. If a water drop link two of them a short circuit is made and this MUST'NT happe. Do you think that between them spray will be enough or is better use silicon in order to cover empty spaces between them and avoid drop formation ?
THX

 

[jiripolivka]

one other information : the pcb has 30 gold pins spaced 5 mm one each other. If a water drop link two of them a short circuit is made and this MUST'NT happe. Do you think that between them spray will be enough or is better use silicon in order to cover empty spaces between them and avoid drop formation ?
THX

All options, conformal coat, wax or epoxy potting , prevent moisture from getting to sensitive points.