Integrated circuit packaging

Integrated circuit packaging is the final stage of semiconductor device fabrication, in which the die is encapsulated in a supporting case that prevents physical damage and corrosion.

The case, known as a "package", supports the electrical contacts which connect the device to a circuit board.

The current-carrying traces that run out of the die, through the package, and into the printed circuit board (PCB) have very different electrical properties compared to on-chip signals.

[1] The integrated circuit package must resist physical breakage, keep out moisture, and also provide effective heat dissipation from the chip.

[1] The materials of the package are either plastic (thermoset or thermoplastic), metal (commonly Kovar) or ceramic.

[4] Early integrated circuits were packaged in ceramic flat packs, which the military used for many years for their reliability and small size.

[6] Surface mount packaging appeared in the early 1980s and became popular in the late 1980s, using finer lead pitch with leads formed as either gull-wing or J-lead, as exemplified by small-outline integrated circuit—a carrier which occupies an area about 30–50% less than an equivalent DIP, with a typical thickness that is 70% less.

[10] Traces out of the die, through the package, and into the printed circuit board have very different electrical properties, compared to on-chip signals.

Combining multiple dies on a small substrate, often ceramic, is called an MCM, or Multi-Chip Module.

[14] In high-powered applications, the die is usually eutectic bonded onto the package, using e.g. gold-tin or gold-silicon solder (for good heat conduction).

For low-cost, low-powered applications, the die is often glued directly onto a substrate (such as a printed wiring board) using an epoxy adhesive.