Small-outline integrated circuit

A Small Outline Integrated Circuit (SOIC) is a surface-mounted integrated circuit (IC) package which occupies an area about 30–50% less than an equivalent dual in-line package (DIP), with a typical thickness that is 70% less. They are generally available in the same pin-outs as their counterpart DIP ICs. The convention for naming the package is SOIC or SO followed by the number of pins. For example, a 14-pin 4011 would be housed in an SOIC-14 or SO-14 package.

SOIC actually refers to at least two different package standards: The EIAJ SOIC body is approximately 5.3 mm (0.21 in) wide, while the JEDEC SOIC body is approximately 3.8 mm (0.15 in) wide. The EIAJ packages are also thicker and slightly longer. Otherwise the packages are similar.

Note that because of this, SOIC is not specific enough of a term to describe parts which are interchangeable. Many electronic retailers will list parts in either package as SOIC whether they are referring to the JEDEC or EIAJ standards. The wider EIAJ packages are more common with higher pin count ICs, but there is no guarantee that an SOIC package with any number of pins will be either one or the other.

The SOIC package is shorter and narrower than DIPs, the side-to-side pitch being 6 mm for an SOIC-14 (from lead tip to lead tip) and the body width being 3.9 mm. These dimensions differ depending on the SOIC in question, and there are several variants. This package has "gull wing" leads protruding from the two long sides and a lead spacing of 0.050 in (1.27 mm).

The picture below shows the general shape of a SOIC narrow package, with major dimensions. The values of these dimensions (in mm) for common SOICs is shown in the table.

Next to the narrow SOIC package (commonly represented as SOx_N or SOICx_N, where x is the number of pins), there's also the wide (or sometimes called extended) version. This package is commonly represented as SOx_W or SOICx_W.

The difference is mainly related to the parameters W_B and W_L.

As an example, the values W_B and W_L are given for an 8-pins wide (extended) SOIC package:

Another SOIC variant, available only for 8-pins and 10-pins ICs, is the mini-SOIC, also called micro-SOIC. This case is much smaller with a pitch of only 0.5mm. See the following table for the 10-pin model:

...
Wikipedia