SOIC COMPONENT PACKAGE

SOIC Component Package

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Overview

NameSOIC (Small Outline Integrated Package)
Synonyms
  • 11-4M1S (Toshiba SO-4, 4.55mm wide body)1
  • 751EP (onsemi SOIC4 W2)
  • R-PDSO (JEDEC wide body SOIC, 7.5mm width, 0.65mm pitch)
  • S8 (SOIC-8, Analog Devices)
  • S8E (Linear Technologies, SOIC-8 with exposed pad)
  • SO (ST Microelectronics)
  • SOIC8E (SOIC-8N with exposed pad, Monolithic Power Solutions3)
  • SOT162-1 (SOIC-16W, NXP4)
  • SSOP4/LSOP04 (onsemi, SO-4, 7.5mm wide body)5
  • WSON (SST, this is a package which shares the same footprint as a SOIC but has a smaller height, not to be confused with the different SON package)
Similar To

SOJ

VariantsThe 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.
MountingSMD
Pin Count8, 14, 16, 18, 20, 24, 28, 32
Pitch

  • 0.65mm (e.g. R-PDSO)
  • 1.27mm (50mill)
SolderabilityRelatively easy to hand solder compared to other SMD packages.
Thermal ResistanceDepends on variant, see below.
Package LxWxHLength and width depends on variant, height is usually between 1.50-2.54mm.
Typical PCB Land AreaDepends on variant, see below.
3D Modelsn/a
Common Uses
  • Linear regulators.
  • Drivers/buffers.
  • High-power MOSFETs (normally in a SOIC-8N, with one pin for the gate, and either 3 or 4 pins for the drain and source).

Overview

WARNING

There are are three different widths of SOIC packages, all which can be referred to as just SOIC by manufacturers in component datasheets! When designing a PCB, make sure to double-check the exact package width matches the PCB footprint/land pattern you’ve chosen.

  1. Package body width of 3.80mm (0.150"). JEDEC standard, commonly used for SOIC packages with a small pin count (16 or less).
  2. Package body width of 5.30mm (0.208"). EIAJ standard[^bib-dexpcb-soic], used for SOIC packages with higher pin counts (>16) or for isolated ICs (e.g. Maxim package SOIC [W8][^bib-maxim-soic-w8]).
  3. Package body width of 7.52mm (0.300"). JEDEC standard, commonly called SOIC Wide or SOIC-W (e.g. Maxim package SOIC (W) variant W20+6)[^bib-maxim-soicw-20-28].

More on these different width SOIC packages below.

SOIC (JEDEC, 0.150" Package Body Width)

The JEDEC version of the SOIC (a.k.a SOIC-xN (SOIC narrow)) family of packages is governed by the JEDEC MS-012-AA standard. There are non-exposed (normally just referred to as SOIC-x or SOIC-xN) and exposed pad versions (which are normally indicated with an “E” in the package name3).

The dimensions for the SOIC-8N package are shown below:

The dimensions for the SOIC-8N component package.

The dimensions for the SOIC-8N component package.

The dimensions for the SOIC-16N component package are shown below:

The dimensions for the SOIC-16N component package.

The dimensions for the SOIC-16N component package.

Land area:

  • SOIC-8: 29.4mm2

Thermal resistance:

  • SOIC-8: 70.6K/W (pads only, no copper fill)
  • SOIC-8: 55K/W (6cm2 of copper, ground pins attached internally to die)
  • SOIC-8: 33.5K/W (1 square inch of copper surrounding package, connected to ground)

SOIC (EIAJ, 0.208" Package Body Width)

Confusingly, the EIAJ standard defines a different body width of 5.3mm (0.208") for the `SOIC`` package, compared to the 3.8mm body width as defined in the JEDEC standard6. Generally used for ICs with a larger number of pins (>16).

SOIC-W (JEDEC, 0.300" Package Body Width)

The SOIC-W (SOIC wide) family of packages is governed by the JEDEC MS-013 and IEC 075E03 standards. NXP’s SOT-162-1 package is a SOIC-16W4.

Package NameLand Area
SOIC-16W136.3mm² (11.9x11.45mm)4
SOIC-28W186.4mm² (10.3x18.1mm)

Pitch

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

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.

Polarity Marks

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 bevelled 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

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.

A SOIC-8 to DIP-8-300 adapter PCB by SparkFun.

A SOIC-8 to DIP-8-300 adapter PCB by SparkFun.

Thermal Resistance And Power Dissipation

This graph shows the maximum power dissipation for the SOIC-8N component package, for various PCB copper areas.

Maximum power dissipation graphs for the SOIC-8N component package.

Maximum power dissipation graphs for the SOIC-8N component package.

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.

The standard pinout for a single MOSFET (N or P-channel) in a SOIC-8 package.

The standard pinout for a single MOSFET (N or P-channel) in a SOIC-8 package.

Examples that follow this pinout include the ST STS25NH3LL (N-channel), the International Rectifier IRF8721PbF-1 (N-channel), and the Vishay SI9407BDY-T1-GE3 (P-channel).

SOIC-4 (SO-4)

The SO-4 package is quite unique from other SO packages. It typically has the same mechanical dimensions as a SO-6 package, but has the two middle pins on either side removed. Typically the SO-6 pin numbering is also kept, such that the remaining pins are numbered 1, 3, 4 and 6. Due to the large clearances between the pins and on the package, this SO-4 package is used for optical isolators.

The SO-4 package is different to the SOIC-4 package, even though these two different names refer to the same package at higher pin counts.

ON Semiconductor uses the case code 751EP for the SOIC-4W package2.

References

  1. Retrieved 2021-12-08, from https://media.digikey.com/pdf/Data%20Sheets/Toshiba%20PDFs/TLP185_04-27-17.pdf. ↩︎

  2. On Semiconductor (now onsemi) (2019, Sep). Bridge Rectifiers, 0.5 A: MB10S (datasheet). Retrieved 2022-03-08, from https://www.mouser.com/datasheet/2/308/1/MB10S_D-2314909.pdf. ↩︎ ↩︎

  3. Monolithic Power Solutions (2012, May 30). MP2497-A: 3A, 50V, 100kHz Step-Down Converter with Programmable Output OVP Threshold. Retrieved 2022-01-20 from https://www.monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/MP2497A/document_id/1972. ↩︎ ↩︎

  4. NXP (2016, Feb 8). SOT162-1: Plastic small outline package; 16 leads; body width 7.5 mm (package information). Retrieved 2022-01-25, from https://www.nxp.com/docs/en/package-information/SOT162-1.pdf. ↩︎ ↩︎ ↩︎

  5. Retrieved 2021-12-08, from https://nz.mouser.com/datasheet/2/308/1/FODM1009_D-2313636.pdf. ↩︎

  6. DEX PCB. Device Overview > SOIC. Retrieved 2022-03-08, from https://dexpcb.com/manual/device_overview.htm. ↩︎

Authors

Geoffrey Hunter

Dude making stuff.

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