Preventing Cleanroom fires

In the past, cleanrooms and wet benches (plastic or stainless steel workstations upon which computer chips are manufactured) often needed to be protected by sprinklers or more expensive special fire-protection systems like carbon dioxide, fine-waterspray, or halon. By the time a cleanroom fire propagated and triggered a sprinkler or special fire protection system, millions of dollars in property damage could already have occurred in the rest of the cleanroom. With FM4910, wet-bench manufacturers and users can now develop plastic materials and equipment capable of resisting fire and emitting little, if any,smoke.

Due to such factors as potential lost earnings, chip makers are requiring suppliers to use materials in wet-bench fabrication that are less flammable. This should reduce the need for additional—and costly—fire protection systems because the materials will be inherently safe when they arrive in the cleanroom. Consequently, interest in cleanroom plastics with low fire risk has soared among semiconductor manufacturers and tool providers since the turn of the millennium. During that time, an increasing amount of tools constructed of FM4910 fire-safe materials have been installed in semiconductor cleanrooms and the frequency of devastating cleanroom fires has plummeted by approximately75 percent.

FM4910 measures two crucial fire-related elements of a product or material:

[b]-The Fire Propagation Index (FPI), an indicator of the tendency of a material to ignite and propagate fire, and

-The Smoke Development Index (SDI), an indicator of the amount of smoke generated.[/b]

For material to be considered fire-safe under FM4910, its FPI must be equal to or less than 6 and its SDI equal to or less than 0.4. Today, scores of FM4910-listed materials and products made with such materials are available from nearly two dozen anufacturers. While FM4910 materials are prevalent in semiconductor cleanrooms, they can easily be applied in other industries that utilize cleanrooms (pharmaceutical, biotech, food processing, etc.). FM4910 fire-safe materials are helping preventcleanroom fires. But they can’t do it alone.

Codes and Standards

The following codes and standards have significantly improved cleanroom fire prevention:

[b]-National Fire Protection Association (NFPA) 318 “Standard for the Protection of Semiconductor Fabrication Facilities”

-Semiconductor Equipment Materials International (SEMI) S2 “Environmental, Health, and Safety Guideline for Semiconductor Manufacturing Equipment”

-SEMI S14 “Safety Guidelines for Fire Risk Assessment and Mitigation for Semiconductor Manufacturing Equipment”

-FM Global Property Loss Prevention Data Sheet 7-7 “Semiconductor Fabrication Facilities”[/b]

Each of these documents recommends the use of fire-safe construction materials for cleanroom applications. In cases where such materials are not used, fixed fire detection and suppression units are the recommended alternative. If neither measure is taken, the results can be catastrophic

In December 2002, FM Approvals issued the Approval Standard for Wafer Carriers for use in Cleanrooms (Class 4911) . This standard provides testing criteria similar to FM4910 in order for a fire-safe wafer carrier to earn FM Approval. This new product test standard will address design and construction features of semiconductor production equipment including:

Control and/or safety interlocks