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DKE German Commission for Electrical, Electronic & Information Technologies of DIN and VDE

Overview

This Part 61340-5-1 of the IEC 61340 series of international standards "Electrostatics" covers the requirements necessary to design, establish, implement and maintain an electrostatic discharge (ESD) control program for electrical or electronic parts, components and equipment that are manufactured, processed, assembled, installed, packaged, marked, operated, tested, inspected or otherwise handled and which are susceptible to damage from electrostatic discharges equal to or greater than 100 V according to the Human Body Model (HBM), 200 V according to the Charged Device Model (CDM) and 35 V on insulated conductors. Isolated conductors were historically represented by machine model (MM). The 35 V limit is related to the level achievable using ionizers specified in this standard. The MM test is no longer required for qualification of devices, only the HBM and CDM tests are. The requirements relating to MM are retained in this standard for process control of isolated conductors only. Any contact and physical separation of materials or flow of solids, liquids, or particle-laden gases can generate electrostatic charges. Common sources of ESD include charged: personnel, conductors, common polymeric materials, and processing equipment. ESD damage can occur when: - a charged person or object comes into contact with an ESD sensitive device (ESDS); - an ESDS comes into direct contact with a highly conductive surface while exposed to an electrostatic field; - a charged ESDS comes into contact with another conductive surface which is at a different electrical potential. This surface can be grounded or ungrounded. Examples of ESDS are microcircuits, discrete semiconductors, thick and thin film resistors, hybrid devices, printed circuit boards and piezoelectric crystals. It is possible to determine device and item susceptibility by exposing the device to simulated ESD events. The ESD withstand voltage determined by sensitivity tests using simulated ESD events does not necessarily represent the ability of the device to withstand ESD from real sources at that voltage level. However, the levels of sensitivity are used to establish a baseline of susceptibility data for comparison of devices with equivalent part numbers from different manufacturers. Three different models have been used for qualification of electronic components - Human Body Model (HBM), Machine Model (MM), and Charged Device Model (CDM). In current practice devices are qualified only using HBM and CDM susceptibility tests. This standard covers the ESD control program requirements necessary for setting up a program to handle ESDS, based on the historical experience of both military and commercial organizations. The fundamental ESD control principles that form the basis of this standard are as follows: Avoid a discharge from any charged, conductive object (personnel and especially automated handling equipment) into the ESDS. This can be accomplished by bonding or electrically connecting all conductors in the environment, including personnel, to a known ground or contrived ground (as on board ship or on aircraft). This attachment creates an equipotential balance between all conducting objects and personnel. Electrostatic protection can be maintained at a potential different from a "zero" voltage ground potential as long as all conductive objects in the system are at the same potential. - Avoid a discharge from any charged ESD sensitive device. Charging can result from direct contact and separation or it can be induced by an electric field. Necessary insulators in the environment cannot lose their electrostatic charge by attachment to ground. Ionization systems provide neutralization of charges on these necessary insulators (circuit board materials and some device packages are examples of necessary insulators). The ESD hazard created by electrostatic charges on the necessary insulators in the work place is assessed to ensure that appropriate actions are implemented, according to the risk. - Once outside of an electrostatic discharge protected area (hereinafter referred to as an EPA) it is generally not possible to control the above items, therefore, ESD protective packaging can be required. ESD protection can be achieved by enclosing ESD sensitive products in static protective materials, although the type of material depends on the situation and destination. Inside an EPA, static dissipative materials can provide adequate protection. Outside an EPA, static discharge shielding materials are recommended. Whilst all of these materials are not discussed in this standard, it is important to recognize the differences in their application. For more information see IEC 169 61340-5-3. Each organization has different processes, and so will require a different blend of ESD prevention measures for an optimum ESD control program. Measures should be selected, based on technical necessity and carefully documented in an ESD control program plan, so that all concerned can be sure of the program requirements. Training is an essential part of an ESD control program in order to ensure that the personnel involved understand the equipment and procedures they are to use in order to be in compliance with the ESD control program plan. Training is also essential in raising awareness and understanding of ESD issues. Without training, personnel are often a major source of ESD risk. With training, they become an effective first line of defence against ESD damage. Regular compliance verification checks and tests are essential to ensure that equipment remains effective and that the ESD control program is correctly implemented in compliance with the ESD control program plan. This part of IEC 61340 applies to activities involving the manufacture, processing, assembly, installation, packaging, marking, maintenance, testing, inspection, transportation or other handling of electrical or electronic components, assemblies or equipment with withstand voltages equal to or greater than 100 V for HBM, 200 V for CDM and 35 V for insulated conductors. ESDS with lower withstand voltages can require additional control elements or adjusted limits. Processes designed to handle items that have lower ESD withstand voltage(s) may still claim compliance to this standard. This standard provides the requirements for an ESD control program. This standard does not apply to electrically initiated explosive devices, flammable liquids, gases and powders. The purpose of this standard is to provide the administrative and technical requirements for establishing, implementing and maintaining an ESD control program (hereinafter referred to as the "program"). Isolated conductors were historically represented by machine model (MM). The responsible committee is DKE/K 185 "Elektrostatik" ("Electrostatics") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.

Document: references other documents

Document: referenced in other documents

Responsible national committee

DKE/K 185 - Elektrostatik