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Cracks on glass to metal seals (hermetic seals)
Q. Hello,
I am a engineer working in GTMS (glass to metal seal) We have a product that is rectangular in shape with no issues with cracking. We currently have a new product with an oval shaped glass for fusing and we get a large number of parts with the glass cracking. The furnace profiles are all the same and fixture materials are the same. Can anybody please help me out on this one. I am stumped. Thanks all.
Glass to metal seal - Fuzhou, China
2005
A. I manufacture glass to kovar seals. A coworker told me about having a problem with glass cracking on round large diameter(5 inch +) glass to kovar seals. The solution that worked for us was to taper the edge of the kovar where the glass bonds to the kovar. Let me know if this works for you. Hope this helps.
Mario Terrazas- Bolingbrook, Illinois
2005
A. With regard to the oval shape, have you conducted a FEA structural analysis? Even if you do not know all of the inputs (glass properties, neutral stress temperature, etc.) it could provide you some insight regarding the high stress points and of course how you might modify the design to address the problem. In addition you might want to determine if the cracks are meniscus type cracks. These are often hard to eliminate but may not impact hermeticity of the seal.
Jim Donaherbuyer - Landenberg, Pennsylvania, USA
October 25, 2011
Q. We need to have a hermetically sealed quartz window with temperature cycling to cryogenic temperature. How do you solder or braze a quartz window to a Kovar sleeve. Does the quartz have to be metallized around the edge ? How do you prep the quartz to bond and seal properly with the Kovar after the brazing process.
Ravi Bainsproduct designer - Allentown, Pennsylvania, USA
December 20, 2010
A. Hi, Ravi. I don't know much on that subject, but I do understand that kovar should be electroplated with a glass-compatible material like electroless nickel, and then the glass is fused to it. Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
December 21, 2010
Q. Hello,
I am an engineer working on products with glass to metal seal. We have a Dia. 60 mm connector with 70 pins. We have individual glass beads for all the pins (compression seal). We are facing cracks on the glass seals. The combination used is: Body-304L, Pins-Alloy52, and; Glass SO5. After this crack we tried with 316L and still cracks were observed. Can someone help me to solve this problem. Thanks
product designer - Sydney
May 21, 2009
A. The glass is not up to the stress that it is under. How well was the glass annealed after it was made. It makes a massive difference. Also, any microscopic burrs on the metal will break the surface tension of the glass and they will break.
James Watts- Navarre, Florida
May 22, 2009
A. It is necessary to match the coefficient of thermal expansion of the metal (commonly kovar) and the glass (which is not linear). The glass and metal suppliers may be able to provide this information but for reliable production you may need to monitor it yourself. You also have to ensure that the glass chosen will 'wet' the metal surface at the sealing temperature.
One common solution is to buy ready made glass/metal seals and fuse them into your connector/leadthrough.
Geoff Smith
Hampshire, England
June 1, 2009
A. In response to Joseph Smith's inquiry from Sidney, your glass to metal seal is a very common compression seal if you use the correct glass material. Typically when sealing 304 or 316 stainless steel either S-8061 or 9013 glass works excellent. I am not familiar with S05 glass but if you choose a glass material that has an CTE of 88 to 93 x 10 neg. 7 you will be fine.
C. Ambrogio- Seabrook, New Hampshire
March 13, 2012
February 4, 2011
Q. Hi
I'm looking for some information on the properties of Electroless Nickel Plating.
I have been advised that ENP coat is not ideal for the assembly which are leak proof and filled with helium.
The assembly has a lid and housing both been ENP coated with tight tolerance.
Can anyone please guide me with right information.
Appreciate your support.
GH
- UK
Any experience buying glass to metal seals from low labor cost country?
RFQ: Does anyone have experience buying glass to metal seals from a low labor cost country like China, India, Indonesia, etc? If possible I am interested in contact information for a firm that delivers higher end quality products.
Jim Donaherbuyer - Landenberg, Pennsylvania, USA
October 25, 2011
Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)
Q. I am facing a peculiar problem of glass cracking (Radial cracks) of the seals when sealing a thin section (0.5 mm thick) steel frame (formed in the shape of a tray with holes).The materials used are steel (C1010) for frame, alloy 52 for pins and SO5 glass.
We make many seals with similar materials but are not facing this problem. Can somebody suggest a solution?
- Bangalore,Karnataka, India
May 29, 2013
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