The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Hobson's choice on glass-to-ceramic seals

What method I should try in sealing glass to ceramic-package using the H77 EpoTek epoxy (or any soft composition) that cures at 150 °C. The problem is that the expansion of the N2 trapped into the package cavity will lift the window, using mechanical force to keep the glass in place will create voids in the epoxy. Trying to cure into a vacuum oven will out-gas the epoxy creating inconsistent epoxy bead.

Thanks for your input.

Vichente Pantea
electronics mfgr. - Waterloo, Ontario, Canada
2003

Stupid as it sounds, you need a cheap effective way to vent the system during the main cure followed by a low temp cure of the tiny vent space. As for restraint of the glass, you need a system that will restrain the glass in a position and not exert any force into the main body. Vacuum curing is very touchy. There is an extremely small range of what will work and that seems to vary by the makeup of the compound (it is never exactly the same) as well as how much it has pre-cured by the time you get a vacuum on it.

James Watts
- Navarre, Florida
2003