Flammability evaluation of clean room polymeric materials for the semiconductor industry

Abstract

A new methodology, identified as the 4910 Test Protocol, has been developed to evaluate the fire propagation and smoke development behaviour of polymeric materials for use in clean rooms for the semiconductor industry. This paper reviews the scientific basis of the concepts and criteria contained in the 4910 Test Protocol. For the acceptance of polymeric materials, two criteria are used: (a) Fire Propagation Index (FPI) less than or equal to 6 (m s(-1/2))/(kWm(-1))(2/3) and (b) Smoke Development Index (SDI) less than or equal to 0.4 (gg(-1)) (ms(-1/2))/(kWm(-1))(2/3). Materials are tested in the ASTM E 2058 Fire Propagation Apparatus (previously identified as the Factory Mutual Research Flammability Apparatus). The Fire Propagation Index (FPI) is formulated from: (a) the Thermal Response Parameter (TRP), which relates the time-to-ignition to the net heat flux to the sample surface, and (b) the chemical heat release rate measured during the upward fire propagation in air having a 40% oxygen concentration to simulate flame heat transfer at large scale. The SDI is related to the smoke release rate and is obtained by multiplying the FPI value by the smoke yield. The smoke yield is defined as the ratio of the total mass of smoke released per unit mass of the vapours of the polymeric material burned. Small and large-scale fire test data have been included in the paper in support of the 4910 Test Protocol criteria. Highly halogenated and high temperature specialty polymeric materials and highly modified ordinary thermoplastics are found to satisfy the criteria.