Ethylene Oxide cleaning of printed circuit boards

Yes. I came close to needing that stuff for a synthesis once, but found an alternative approach that spared the need for this.

There is something screwy with the practice of gassing items with EtO for medical sterilization when it has such low TLV/PELs and is a "de minimis" carcinogen.

Something like a PCB with components would certainly retain trace amounts of the stuff, unless baked out afterward in vacuum.

Is a vacuum bakeout part of the normal procedure for EtO sterilizations?

Good day!

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Christopher R. Carlen
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Chris Carlen
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Hi All,

Has anybody experience with Ethylene Oxide cleaning of a PCB containing SMD parts and connectors? Is a coating necessary? Will connectors stand up (over time) after cleaning?

We are building a PCB that will be incorporated in a larger assembly for medical application - hence the EtO cleaning...

TIA!

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 - René
Reply to
René

EtO, nice stuff....

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martin

"An eye for an eye makes the whole world blind" Gandhi

Reply to
martin griffith

OK - so I will not inhale.....:-)

Anyway - we have to supply the PCB's - our customer does the dangerous stuff. All we must do is to make the product survive the EtO.

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 - René
Reply to
René

snip

Isn't that what US president's claim?

martin

"An eye for an eye makes the whole world blind" Gandhi

Reply to
martin griffith

Ha! that's what all Americans claim. :)

Reply to
Mark Jones

Remember, just because it is sterile doesn't mean that it is not contaminated.

Al

Reply to
Al

Hello René,

EtO is very corrosive. I have dealt with a lot of electronics that got sterilized that way. There isn't much else you can do with electronics. Radiation, for example, will destroy most of the stuff. Same with processes that require high temperatures.

We had potted and non-potted designs. However, it was all disposable so there were no repeat sterilization although we did have to do those to validate margins etc.

Also, keep in mind that you will have to do other stuff as well, such as passing the biocompatibility test. That starts with lots and lots of paperwork. Keep in close contact to the Regulatory/QA folks of your client.

And never, never, touch anything before the outgassing phase is completed. But people who work under a proper QA system normally won't let you anyway.

Regards, Joerg

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Reply to
Joerg

Given the fact that the PCB will be disposable and will contain fine pitch tracks and several connectors (micromatch, slotted 1/10" headers), what is advisable relative to coatings, connector pin materials (gold, tin etc.)

Thanks for answering!

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 - René
Reply to
René

Hello René,

Our circuit boards were regular issue, no fancy coatings. But with respect to surface coating and connectors I would study a bit, especially if you are facing multiple EtO cycles. This may be a start:

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For connectors, gold plating is popular. But always get the manufacturers blessing first. Here is a start:

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Most major connector manufacturers and especially the ones catering to the medical device industry (such as LEMO S.A.) can guide you. As I said before, a very important aspect is that you receive sufficient data for bio burden. Without such data a connector may be useless no matter how good it is. Med is a heavily regulated industry, and it should be. So, the QA folks are going to want to know what's in your design from a chemistry point of view.

Regards, Joerg

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Reply to
Joerg

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