Kovar has a wide usage in the electronics industry, such as metal parts bonded to hard glass envelopes. These parts are used for such devices as power tubes and X-ray tubes, etc. In the semiconductor industry, Kovar is used in hermetically sealed packages for both integrated and discrete circuit devices. Kovar is provided in a variety of forms to facilitate efficient manufacturing of various metal parts. It has thermal expansion characteristics matching those of hard glass. Used for matched expansion joints between metals and glass or ceramics.