Guidelines For Installing Hermetic GPO And GPPO Connectors

Introduction:

Microelectronic packaging applications often require the package to be hermetically sealed to protect the delicate and sensitive components installed within. Many applications also require that the packages be light and compact. To meet these goals Corning Gilbert has developed single component hermetic versions of our popular GPO and GPPO connectors. They are small, lightweight, and hermetically sealed.

Construction

In order to properly use the hermetic connectors it is necessary to understand their basic construction. The material used for the housing and pin is a nickel-iron-cobalt sealing alloy per ASTM F15 and is commonly known as Kovar™. The dielectric support is made of Corning 7070 lithia potash borosilicate glass. It is necessary to use these materials mainly because these materials have a similar coefficient of thermal expansion (CTE). Since the CTE's are closely matched, the type of seal that these connectors provide is known as a "matched" seal as opposed to a compression seal. In the manufacturing process, a preform of the Corning 7070 glass is fired into the connector and fills the space between the Kovar pin and the Kovar housing. The glass does not adhere directly to the Kovar. It actually adheres to an oxide layer developed in a process prior to the glassing process. Figure 1 shows the general hermetic connector construction. As far as electrical performance goes, the materials used are not ideal. Kovar is magnetic and the glass has a high loss tangent. Dielectric constant is also considered high for connectors. These materials represent the compromises necessary to achieve a hermetically sealed package using one piece connectors.

Click here to download the complete application note in PDF Format.