„Machine-Model“ („MM“)

The so-called "machine-model" ("MM") was originally developed as a "worst-case" human-body-model (HBM) with negligible body resistance, increased body capacitance and reduced charging voltage. It was first standardized 1981 in Japan. Starting in the mid-1980s this "worst-case" human-body-model was increasingly used to model discharges between metallic conductors and erroneously denoted as "machine-model" ("MM"). In the following years, the "MM" was claimed to describe the discharge of charged machines, machine parts, cables and printed circuit boards (PCB). However, such discharges are in fact more realistically described by the charged-device-model (CDM), cable-discharge events (CDE) and the charged-board-model (CBM), respectively. At the same time, the results obtained with "MM" testers were found to suffer strongly from parasitic effects. As a result, the "MM" standards of JEITA, JEDEC, ESDA and AEC have meanwhile been demoted, decommissioned or abolished.