glass to stainless

[cambria]

I need to hermetically seal a small glass lens to a metal base. Base can be in SS or similar. Environment is in water or alcohol or hydrocarbons, moderate temp range. I have 40,000 pieces to seal.

thanks

dj

 

[arunmrao]

You can use Invar metal for such applications

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[cambria]

Invar is very high temp I believe. I am looking for a preform or a paste that will form the hermetic seal, and that has a low melting temp - say 200 C (if at all possible).

dj

 

[arunmrao]

Invar can be used in low temperature applications too. It has nearly zero coefficient of expansion.hence ideally suited for glass joinery.

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[EdStainless]

What temp range is this supposed to work over? SS have very high thermal expansion and glass is very low. You may need an intermediate layer to minimize the strain on the joint.

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Plymouth Tube

 

[cambria]

Temp range fairly mild, -40 to +60C, but really more typically -20 to +50C, no shock temp change, ie 0 to 25C over a couple hours.

We can use aluminum, invar or kovar (a bit pricey. We have been using aluminum.

dj

 

[unclesyd]

You might want to look at Indium Solders for your application.
There is considerable information on this site but it is a little convoluted.

http://www.indium.com/techlibrary/nonmetallicbonding.php

 

[cambria]

Thanks. Looks like Indium is not so good with some chemicals (halogens, halides, etc) but I have a sample coming up as of 2 minutes ago. I would have to metalize the edge of the little glass lens (pure indium will wet to glass but not the solders)which in itself will be a challenge at 40,000 pieces per year.