Metal packaging is a form of electronic packaging that uses metal as a shell or base, and the chip is mounted on the shell or base directly or through a substrate. Most electronic packaging uses glass-metal packaging technology. It is widely used in the packaging of hybrid circuits, especially microwave devices, and has good air tightness, especially in the aviation field. Traditional metal packaging materials include Fe, Cu, Mo, W, Ni and other alloys, and the shells are mostly gold-plated.

The characteristics of metal packaging are: the packaging shell can integrate some components (such as hybrid integrated A\/D or D\/A converters), which can diversify the package shape, fast heat dissipation, small size, and low cost. In metal packaging, the packaging structure, size and packaging materials should be reasonably designed according to the transmission delay, crosstalk, heat dissipation and other requirements of the packaged circuit or device.

The most commonly used materials in metal packaging are copper, aluminum, Kovar, copper-tungsten and copper-molybdenum alloys. The characteristics of the main metal packaging materials are shown in Table 8. As can be seen from Table 8, Cu and Al have high thermal conductivity and Kovar has the lowest CTE. They have advantages in heat dissipation and matching respectively;

CuMo alloy and CuW alloy have higher thermal conductivity and matching CTE, but their density is very high, so they are not suitable for applications that require weight, especially the packaging of today's popular portable electronic products. Metal packaging shapes include round, diamond, flat, shallow cavity and deep cavity. The main processes of metal packaging are structural design, machining, inspection, pre-processing, shipping, fusion, inspection, and post-processing.