Abstract

In the past and currently, people have always been the main sources of electrostatic charges. All movements generate electrostatic body voltages. Employees of an electronic manufacturer must be aware of this. Normally, sufficient ESD control steps are already realized to discharge possible existing electrostatic charges and to avoid generation. People may be controlled. Machines, and the automatic handling process as well, become more and more important as another risk source of electrostatic charges. Caused by the permanent movement of electronic components, charges are divided (charge separation) and electrostatic charges are generated. The movement processes are realized quickly. PWBs are also significant charge sources. Their large surfaces and capacity may store large charges. New failure models (CBM, FICBM) are just the beginning.

Introduction

All electronic components and assemblies are at risk for electrostatic discharges. Producers, suppliers, distributors and users have to realize the ESD control system during the entire manufacturing process, measurements and application. All active electronic components, beginning with simple diodes, transistors or complex inner circuits, require an external ESD control system. In the next step, SMD resistors and condensers, and prospectively NEMS and MEMS, will be included in this danger category. Initial tests show that these passive components can be damaged through electrostatic discharges.

The structures of electronic components are becoming smaller. Already 5 volts of an electrostatic charge are enough to change the structures in small electronic components. The structures will achieve such small dimensions, so electrostatic charges can cause permanent damages. In the year 2020, the sizes of the electronic components will be less than 15 nm. Electrostatic charges of 0.04 nC and electrostatic fields of 15 V/cm will be enough to damage electrostatic sensitive devices (ESDS) permanently.

Basics

In the last few years, many directions and worldwide standards for the static control handling of ESDS have been created. The basic principles of all steps are the safe (and slow) electrostatic discharge, as well as the avoidance of electrostatic charge developments. These basic principals are necessary. They are included in all directions and standards. The international standards IEC 61340-5-1 and IEC 61340-5-2 contain these basic requirements for the protection of electronic devices and components against electrostatic discharges. Additionally, users can find an entire section with directions for an ESD control system in the American Standard ANSI/ESD S20.20.

Both standards are confined to the main reason--"the human being." The requirements to machines are not considered, although such special requirements must be created in the future. A start is the standard ANSI/ESD SP10.1-2007, "Automated Handling Equipment (AHE)." This standard only describes the requirements to the grounding of machines and the handling of materials, which may not be charged, as well. Another document is already prepared in the International Electrostatic Committee (IEC). This will describe special requirements.