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Five Reasons to Consider Polycrystalline Ceramic Seals Instead of Glass Seals for Hermetic DC Connectors
Rick Kalkowski, Marketing Administrator, PA&E, a Division of Hermetic Solutions Group
1. More Pin Material Options
The glass sealing process for hermetic DC connectors requires the use of extremely heat-resistant pin materials that can survive the melting temperature of glass fully intact, and Kovar, a ferrous nickel/cobalt alloy, is one of the most popular. Polycrystalline ceramics seal at a lower temperature than glass, which accommodates the use of copper alloy pins, such as beryllium copper and chrome copper, as well as platinum, platinum clad, or Inconel pins.
Figure 1: Yellow ceramic-to-metal seals surround high-reliability BeCu pins in a hermetic Micro-D connector.
2. Higher Electrical Conductivity
Beryllium copper (BeCu) is a popular pin material in connectors that use ceramic-to-metal seals. In a Micro-D format, for example, a Kovar pin with a 0.018” diameter will carry 0.45A while a BeCu pin of the same pin size will carry 2.58A. BeCu pins also exhibit high contact force, high reliability, and long-lifetime performance, which makes them well suited for use in harsh environments.
3. Crack-Proof Seals
If you’ve ever had a stone strike and crack the top your car windshield, you know that it’s only a matter of time before that crack makes its way across the glass. The same thing happens with glass-sealed connector pins. If a ssure starts at the top of a glass seal, it is very likely to follow a path to the bottom and result in a hermetic failure. Ceramics like PA&E’s patented Kryo ex® polycrystalline ceramic, which is a multiple-phase derivative of ceramic oxide crystalline silicates, have a randomized crystalline structure that allows the material to effectively relieve
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