The explosion of electronic related technology in recent years has rekindled interest in electrostatic discharge (ESD). The ESD Association (see www.esda.org) released an ESD Technology Roadmap in 2005 that paints a less than rosy picture for ESD protection and ESD susceptibility due to the major advances in electronic device expectations as they relate to cost and performance. Look at the vast array of features offered just in the past year in portable communication devices and personal computers to get an idea about these increases in performance. However, we all need to understand that these performance advances do not come without a price. The price, while it may not have to be paid quite yet, is the loss or at least reduction of on-chip ESD protection. As shown in the ESD Technology Roadmap, on-chip protection devices are left out to give way to space that is needed for active component features. This limits the ability of device designers to provide on-chip protection networks to reduce the riskof ESD damage that can occur in handling and process situations.

Process Considerations
If components are indeed becoming more sensitive, it is important to reduce exposure levels within any handling scenario. The industry has a fairly good understanding of what to do in manual operations where personnel have to handle unprotected ESD susceptible parts. In the fundamental ESD control scenario, all conductive items, including personnel, are interconnected (bonded) and attached to a known ground when possible. These actions equalize the electrostatic potentials between all the conductive items so that there is no difference in potential between items. When the conductive items are grounded, the electrical potential is controlled by the resistance in the ground path. A level of 35 mega ohms or less is the commonly accepted resistance to ground value for most applications. At this level, a person cannot generate more than 100 volts, even with rapid movements. High sensitivity applications require a lower potential; perhaps as low as 5-10 volts in extreme situations. This level may be become the norm in many applications in the near future. This means that standard dissipative shoes, shoe grounders, floors, wrist straps, garments, and many other ESD control technical elements will need to be replaced with items with lower levels of resistance in order to maintainthese very low electrical potentials.

Most processes today use a wide variety of automated handling equipment. ESD Association Standards Working Groups and private companies are developing methods and tools that can make measurements within equipment while the equipment is operating. While there is still work to be done, some recently available measurement tools have allowed practitioners to start developing an understanding of electrostatic risks inside of process equipment. The goal will be to allow manufacturers to state with certainty what their processes are capable of handling from an ESD perspective. In the near future, when a customer asks an Electronic Manufacturing Services company (contract manufacturer) if they can handle a part sensitive to 50 volts Charged Device Model (CDM) or 25 volts Machine Model (MM) the contract manufacturer will be able to give an answer backed by meaningful measurements and statistical data. Up until recently, process lines could only be realistically rated for Human Body Model (HBM) levels since only the human activity could be measured with any degree of certainty. While still important, human activity is limited in many processes today since automated handling equipment adds speed and repeatability to any manufacturing endeavor.

Other Considerations
In addition to process monitoring, facility certification is enjoying resurgence in importance. ANSI/ESD S20.20 — ESD Association Standard for the Development of an Electrostatic Discharge Control Program for — Protection of Electrical and Electronic Parts, Assemblies and Equipment (Excluding Electrically Initiated Explosive Devices) will soon become a global standard as the International Electrotechnical Commission (IEC) adopts its own version of S20.20 in a revision of IEC 61340-5-1. The ESD Association will release a revision of S20.20 later in 2006 or early in 2007. The IEC and ESDA documents are technically identical. The Registrars that provide Certification Audits to S20.20 today will receive training shortly that will allow them to certify against the IEC document as well as the ANSI version. This will greatly expand the reach of the ESD Association’sFacility Certification program and will add credibility and value.

The ESD Association also offers individual certification as ESD Program Manager. A ten class tutorial set prepares individuals to take a comprehensive 8-hour written exam.

Conclusion
Device technology changes to increase performance will also increase ESD susceptibility over the next few years. The ability to monitor processes will go a long way towards reducing manufacturing risks associated with ESD and electrical fields. Standards are keeping pace with process requirements. Facility certification assures that process controls are in place and individual certification helpsto develop knowledgeable personnel.

David E. Swenson is the ESD Association Sr. Vice President and an elected Director. A retired 3M Technical Specialist,he is currently president of AffinityStatic Control Consulting,LLC,Round Rock,TX.He can be reached at inquire@affinity-esd.comor 512-244-7514.