ANSI ESD STM-11.13-2004 pdf download For the Protection of Electrostatic Discharge Susceptible Items Two- Point Resistance Measurement
1.2 Scope This standard test method is intended for measuring the resistance of items in the range of 10*>R<1012 ohms. 2.0 REFERENCES ANSI/ESD STM11.11 Surface Resistance Measurement of Static Dissipative Planar Materials. EOS/ESD Advisory 1.0 Glossary of Terms. ASTM D257-78 (re-approved 1983), Standard Test Method for D-C Resistance or Conductance of Insulating Materials ASTM D2240 Standard Test Method for Rubber Property-Durometer Hardness' 3.0 DEFINITIONS Terms used in this document are in accordance with the definitions found in ESD ADV1.0 Glossary of Tems. 4.0 GENERAL DISCUSSION This method is recommended for testing items with irregularly shaped surfaces. Conventional concentric ring and parallel bar electrode configurations are used for testing planar items only. However, most packaging items are not planar. Examples include shipping tubes, trays, tote boxes and carrier tapes. This probe employs springs to apply consistent contact pressure between the electrode and the item. Force created by springs is subject to variance from wear, contamination and manufacturing tolerance. This variance is acceptable for this application. Elastomeric electrodes compensate for uneven item surfaces. These features yield consistent results between laboratories and test operators. 5.0 EQUIPMENT 5.1 Probe Refer to Figure 1 and Table 1. This two-point probe consists of an insulated metal body with a Teflon° insulator inserted into each end. One insulator holds test leads; the other holds receptacles that accept spring- loaded pins. One receptacle is surrounded by a cylindrical insulator, which is surrounded by a metal shield. The pins are gold plated and have a spring force of 0.465 kg (16.4 ounces) +10% at a travel of 0.00432 m (0. 170 inches). The pin tips are machined to accept friction ftted 0.00318 m (0.125 inch) diameter electrically conductive rubber electrodes. The rubber has a Shore-A (IRHD) durometer hardness of 50-70 (ASTM Method D2240). The electrodes are 0.00318 m (0.125 inches) long. Electrode volume resistivity is <500 ohm-cm. 5.2 Sample Support Surface An insulative surface when used for specimen support. shall have a resistance of greater than 1.0x1013 ohms when measured in accordance with ASTM D-257.