On 24/07/2010 13:26, Carl Denk wrote:
> Why do the PCB's need to be exposed to the high humidity?
>
> On 7/24/2010 8:14 AM, V G wrote:
>> Hi all,
>>
>> As I have mentioned previously, I am designing a temperature and
>> humidity control system for my university lab that I am working in.
>> Several dsPIC controlled remote terminal units (RTUs) will be placed
>> in self contained chambers. These RTUs will provide a means to log and
>> control temperature and humidity. Within the chambers are special
>> fungi that require a high relative humidity (RH) level to grow
>> effectively - sometimes even close to 100% RH.
>>
>> I am concerned that water from the air may condense on the PCBs and
>> cause problems (such as undesirably conducting electricity, and so
>> on). Should I be worried about this? If so, what can I do about it?
>>
>> Also, are there any other potential problems that I should be aware of
>> for running home-made electronic equipment in a high humidity
>> environment?
>>
>> Will a crystal/crystal oscillator deviate enough from it's desirable
>> frequency in a high humidity environment to cause serial communication
>> issues?
>>
Varnish/seal everything. What the army in WWII called "tropicalised".

Also only have probes and moisture/heat source in the high RH=20
environment. Put the electronics elsewhere. Some components don't like=20
fungi. Some fungi may secrete liquids that attack wiring or even insulation=
?



Crystal is more concerned about temperature. But unless you are doing=20
very accurate timing and the crystal has a trimming capacitor to fine=20
tune frequency, it's unlikely to matter.

--=20
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