What is SEMI F47?
SEMI, the industry association for the semiconductor industry, has developed the SEMI F47 voltage sag immunity standard. Information about SEMI F47 - The Voltage Sag Immunity Standard.

What does SEMI F47 Do?

  1. SEMI F47 sets out the required voltage sag tolerance for semiconductor fab equipment.
  2. The latest edition is SEMI F47-0706. PSL led the team that wrote this update.
  3. The main change in SEMI F47-0706 is that the old SEMI F42 testing standard has been eliminated. Instead, IEC 61000-4-34 is used as the test standard.

SEMI F47 is an industry standard that sets out, in 6 pages, the requirements for voltage sag immunity in semiconductor fab equipment.

Learn More about SEMI F47

You can purchase copies of these standards from SEMI for $50 each, or you can quickly and easily obtain a free set of Application Notes on a CD-ROM from PSL -- just send us an e-mail at [email protected] with your name and address. (Trouble with this link? Just give us a call and we'll take care of it.)

What Are The Requirements?

In essence, SEMI F47 requires that semiconductor processing equipment tolerate voltage sags on their ac power line. Specifically, they must tolerate sags to 50% for up to 200 ms, sags to 70% for up to 0.5 seconds, and sags to 80% for up to one second. In addition to these requirements, SEMI F47 recommends that equipment tolerate sags to 0% for one cycle, sags to 80% for 10 seconds, and continuous sags to 90%, but these are not part of the requirements.

SEMI F47 graphs sag depth vs. duration, in a similar curve to the CBEMA curve. This F47 graph includes both requirements and recommendations.

Who Uses The SEMI F47 Standard?

SEMI F47 suggests that semiconductor manufacturers may use this sag standard whenevery they purchase equipment. Major semiconductor manufacturers require compliance, including Texas Instruments, Freescale, IBM, and others.

SEMI F47 says that you must use IEC 61000-4-34 (an international standard that PSL helped to write) to test compliance. It describes safety procedures, processing modes, test sequences, phase connections, test equipment, and reporting requirements.

PSL's sag generators are designed specifically to test according to SEMI F47 and IEC 61000-4-34.


Use IEC 61000-4-34 as the test standard for verifying compliance with SEMI F47. For more information, contact PSL.

Useful SEMI F47 Links

Sag sensitivity - Five ways equipment fails during voltage sags
CBEMA curve - voltage sag depth and duration at world-wide semiconductor plants
Sag immunity - Inexpensive, simple ways to increase sag immunity

Alex McEachern, 9/2007

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