People pose the biggest threat to ESD sensitive components. However, when properly trained, operators can become the key weapon in the fight against ESD. Every person coming into contact with ESD sensitive items should be able to prevent ESD related problems before they occur or provide immediate action when they do occur. Today’s blog post will explain in detail the role operators play in ESD Protection and how your company can support them in the fight against ESD.
Introduction
As an employee, the invisible threat of ESD should be of great concern to you. ESD damage can significantly reduce your company’s profitability. This may affect your company’s ability to compete in the marketplace, your profit sharing and even your employment. Everyone likes to take pride in their work, but without proper ESD controls, your best efforts may be destroyed by ElectroStatic discharges that you can neither feel nor see.
Perhaps the most important factor in a successful static control program is developing an awareness of the “unseen” problem. People are often a major factor in the generation of static charges. Studies have shown that personnel in a manufacturing environment frequently develop 5000 volts or more by just walking across the floor. This is “tribocharging” produced by the separation of their shoes and the flooring as they walk.
A technician seated at a non-ESD workbench could easily have a 400-500 volt charge on his or her body caused not only by friction or tribocharging but additionally by the constant change in body capacitance that occurs from natural movements. The simple act of lifting both feet off the floor can raise the measured voltage on a person by as much as 500-1000 volts.
Educating your personnel is therefore an essential basic ingredient in any effective static control program. A high level of static awareness must be created and maintained in and around the ESD protected area. Once personnel understand the potential problem, it might help to reinforce this understanding by hanging up a few static control posters in strategic locations. No technician needs an unprotected person wandering over and touching things on the service bench.
The invisible enemy
The biggest issue with ElectroStatic discharges is that you can neither see nor feel the threat. Daily life has other examples of hidden enemies where careful procedures must be followed to regularly obtain positive results. One example is sterilization which combats germs and contamination in hospitals.
Damage caused by invisible and undetectable events can be understood by comparing ESD damage to medical contamination of the human body by viruses or bacteria. Although invisible, they can cause severe damage. In hospitals, the defense against this invisible threat is extensive contamination control procedures including sterilization.
We are aware of the benefits of sterilization in medicine. We must develop the same attitude towards ESD control and “sterilize” against its contamination. Just as you would never consider having surgery in a contaminated operating room, you should never handle, assemble or repair electronic assemblies without taking adequate measures against ESD. For the hospital to sterilize most of the instruments is not acceptable; actually, it may waste money. Every single instrument needs to be sterilized. Likewise, it is not acceptable to protect the ESD sensitive items most of the time. Effective ESD control must occur at each and every step where ESDS items are manufactured, processed, assembled, installed, packaged, labelled, serviced, tested, inspected, transported or otherwise handled.
Everyone handling sensitive components should:
- “recognize ESD threat
- know what equipment to use, and how to use it
- know the correct ESD procedures, and work to them
- know how to check equipment
- know which packaging to use
- take corrective actions when required.” [Source]
It is obvious that ESD training of personnel is a prerequisite for a functioning ESD control program.
Training
ESD training needs to be provided to everyone who handles ESD sensitive devices – that includes managers, supervisors, subcontractors, cleaners and even temporary personnel. Training must be given at the beginning of employment (BEFORE getting anywhere near an ESDS) and in regular intervals thereafter.
“Initial and recurrent ESD awareness and prevention training shall be provided to all personnel who handle or otherwise come into contact with any ESDS [ESD sensitive] items. Initial training shall be provided before personnel handle ESDS items. The type and frequency of ESD training for personnel shall be defined in the Training Plan. The Training Plan shall include a requirement for maintaining employee training records and shall document where the records are stored. Training methods and the use of specific techniques are at the Organization’s discretion. The training plan shall include the methods used by the Organization to verify trainee comprehension and training adequacy.” [ANSI/ESD S20.20-2007 section 7.2]
ESD training should include:
- an introduction to ESD – what it is, what it’s caused by and how to control it
- how to handle sensitive devices and what precautions to take when coming into contact with them
- how to identify and mark ESD sensitive items
- an overview of the ESD Standard.
For operators working in assembly, repair or field service, job specific training will be required, too.
If visitors are entering an EPA, they must possess basic ESD awareness and understand how to use their wrist straps and footwear.
Operator’s safety comes first
One final word of warning: while ESD control is important, it is of secondary importance to employee safety. ElectroStatic charges or static electricity can be everywhere; however, conductors can be effectively grounded and charges removed to ground. A fundamental rule in ESD control is to ground all conductors, including people. BUT: Personnel should not be grounded in situations where they could come into contact with voltage over 250 volts AC.