In the 1993 training manual "Mass Flow Control in a Semiconductor Process," Sematech, Austin, Texas, reported that 70 of mass flow controllers (MFCs) replaced by semiconductor fabs were later found to work perfectly. While results vary from study to study and industry to industry, it's clear that too many MFCs are being replaced needlessly, because of misdiagnosed gas-flow problems that masquerade as MFC failures but lie elsewhere in the gas delivery system. Understanding how a MFC works can help fix blame where it belongs.
展开▼
