|Name||SOIC (Small Outline Integrated Package)|
|Variants||The SOIC family contains packages with a varying number of pins. There are also two width's for SOIC packages, narrow width (3.9mm wide body, SOICx_N) and wide width (7.5mm wide body, SOICx_W). The width is usually expressed by the addition of _N or _W to the end of the package name. If the width is not mentioned, it is most likely going to be narrow width.|
|Pin Count||8, 14, 16, 18, 20, 24, 28, 32|
|Solderability||Relatively easy to hand solder compared to other SMT packages.|
The dimensions for the SOIC-8N package are shown below:
The dimensions for the SOIC-16N component package are shown below:
Most SOIC packages have a pitch of 1.27mm (50mil) and usually have Gullwing leads. When used for regulators, sometimes the many ground pins are connected internally to the die attach flag, providing better heat sinking capabilities. SOIC packages use leadframe technology.
The SOIC package R-PDSO defined by JEDEC has a non-standard pitch of 0.65mm (and the standard wide body width of 7.5mm).
Pin numbering is the same as a DIP package, in that pin 1 is at the top left, and then pins are numbered sequentially down the left-hand side, then up the right hand-side.
There are three ways of indicating the polarity on a SOIC package. The first two, a dot or a notch, indicate pin 1 or the top of the chip. The third way is not so obvious, and features a beveled edge along the side that pin 1 is on (so for SOIC-8, the bevelled edge would be on the side with pins 1 to 4).
The WSON package by SST is lower in height than a standard SOIC package, but is designed to use the same PCB footprint.
Adapter PCBs for the SOIC family of packages are widely available due to the popularity of the package.
SparkFun makes a SOIC-8 to DIP-8-300 adapter PCB.
Thermal Resistance And Power Dissipation
This graph shows the maximum power dissipation for the SOIC-8N component package, for various PCB copper areas.
Standard Pinout For MOSFETs
The SOIC-8 component package is commonly used for medium-power N and P-channel MOSFETs. Most of these MOSFETs have the exact same pinout (both N and P-Channels!), as shown in the below diagram.
Note: As far I’m aware, this is not specified in any standard, but is just an industry default. Also, this only applies to SOIC-8 packages with 1 MOSFET inside them.