sterilization of circuits

[JayLau]

Hi,

I'm currently doing a project which involves sterilization of circuitry.
How are circuits normally sterilized?
Can anyone provide met with more info.

Thx in advance,

Jay

 

[nbucska]

search for "chemical sterilization"

<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[JayLau]

Hmm sorry uh I know the steps,

but what I mean is how are the circuitry normally protected when they need to be sterilized? special material coating or something like that?

Jay

 

[IRstuff]

Depends on the process used.

There are environmental, conformal coatings that are often used such as parylene

TTFN

 

[itsmoked]

There are three standard techniques for sterilizing
stuff.

1) Radiation, generally using Cobalt 60 which generates major ionizing radiation that would probably injure some ICs. This also heats the product up. Product coming out of a CO60 sterilizer is generally very warm.

2) Autoclaving: Essentially a pressure cooker. While IC's are relatively well protected from water these days a pressurized steam environment WILL drive H2O into ICs. Which definitely will wreck them.

3) ETO: Ethylene Oxide. Which is considered a cold sterilizing procedure, though it isn't "cold" ~110F. ETO will attack circuit board substrate but slowly.
The general process is to package the "to be" sterilized product in a gas permeable bag that gas can go through but viruses cannot. This allows easy handling after sterilization.

So if you really need sterilized circuits you will probably need to look into the ETO process. There are many ETO contract sterilizers out there.