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AN668

APPLICATION NOTE

July 2001

1.

POWER DEVICES AND SURFACE MOUNTING

Use of Surface Mount Technology (SMT) has dramatically increased in the last 20 years, moving from consumer

to professional applications and serving highly demanding markets like telecom, industrial and automotive.

Major advantages expected from SMT are size reduction, automated board mounting, high reliability and cost

effectiveness; larger density of functions is achieved in smaller systems.

Evolution of SMT drove the development of several new packages for discrete and IC devices: SOT23,

SOT194, TO263, SO, PLCC, PQFP with many options in pin pitch, size and thickness.

All of them are compatible with the surface mount technique, based on fast picking and placing from tapes or

trays, followed by mass soldering. Mounting lines are almost totally automated, with high throughput and high

yield.

Only a few devices are not yet compatible with SMT principles: a few "exotic" components like large capacitors,

resistors, inductors, varistors, etc. and almost all the power semiconductor packages. Several drawbacks are

associated with existing power packages:

by P. Casati & C. Cognetti

A New High Power IC Surface Mount Package Family: PowerSO-20™

& PowerSO-36 Power IC Packaging from Insertion to Surface Mounting

A new, high power IC surface mount package family is

introduced in this note. It is called PowerSO family and

has the Jedec registration MO-166.

STMicroelectronics developed PowerSO in order to

answer the increasing demand of miniaturization and

quality in power applications. Automotive, industrial,

audio and telecom markets will take advantage of the

new package, by introducing the use of Surface Mount

Technology in the production of power systems.

PowerSO-20 and PowerSO-36 are the elements of the

MO-166 family having 20 leads at 0.050 inch pitch

(1.27 mm) and 36 leads at 0.026 inch pitch (0.65 mm)

respectively. These packages are in mass production

since 1995.

This note is intended to compare the PowerSO-20/36 with alternative surface mount solutions and to

the existing Multiwatt package, the well known "double TO-220" developed by STMicroelectronics in

late 70s.

Data presented here demonstrates that PowerSO-20 is the real successor of Multiwatt for surface mount

applications and is becoming a milestone in power package technology with PowerSO-36 as Multiwatt

did 20 years ago.

PowerSO-20

™ – Jedec Registration MO-166