Semiconductor package

The package provides a means for connecting it to the external environment, such as printed circuit board, via leads such as lands, balls, or pins; and protection against threats such as mechanical impact, chemical contamination, and light exposure.

[1] A hermetic package allows essentially no gas exchange with the surroundings; such construction requires glass, ceramic or metal enclosures.

Modern surface mount devices eliminate most of the drilled holes through circuit boards, and have short metal leads or pads on the package that can be secured by oven-reflow soldering.

[4] Some devices, intended for high-reliability or aerospace or radiation environments, use ceramic packages, with metal lids that are brazed on after assembly, or a glass frit seal.

[5][6] A very few early semiconductors were packed in miniature evacuated glass envelopes, like flashlight bulbs; such expensive packaging was made obsolete when surface passivation and improved manufacturing techniques were available.

Such devices are used when requirements exceed the performance (heat dissipation, noise, voltage rating, leakage current, or other properties) available in a single-die integrated circuit, or for mixing analog and digital functions in the same package.

In a technique called flip chip, digital integrated circuit dies are inverted and soldered to a module carrier, for assembly into large systems.

Pressure-sensing integrated circuits require a port on the package that can be connected to a gas or liquid pressure source.

Special isolation amplifier devices include high-voltage insulating barriers between input and output, allowing connection to circuits energized at 1 kV or more.

The very first point-contact transistors used metal cartridge-style packages with an opening that allowed adjustment of the whisker used to make contact with the germanium crystal; such devices were common for only a brief time since more reliable, less labor-intensive types were developed.

[1] Just like vacuum tubes, semiconductor packages standards may be defined by national or international industry associations such as JEDEC, Pro Electron, or EIAJ, or may be proprietary to a single manufacturer.