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December, 2019


Avoiding Five Common Mistakes in ESD Control


By Kathleen Ranneck, Corporate Marketing Manager, Desco Industries, Inc. M


any companies implement an electrostatic discharge (ESD) control program with the aim


of improving operations. Effective ESD control can significantly im - prove productivity, quality and cus- tomer satisfaction. Problems arise when an organi-


zation invests in ESD protective products or equipment and then mis- uses them. Misuse of an ESD protec- tive product or equipment wastes the investment and can cause more harm than good. For a successful ESD control


program, ESD protection is required throughout the manufacturing pro - cess, from goods-in to assembly and all the way on to inspection. Anyone who handles electrical or electronic parts, assemblies or equipment sus- ceptible to damage by electrostatic discharges should take necessary precautions. Just like viruses and bacteria


can infect the human body, ESD can be a hidden threat that is unable to detect with the naked eye. Hidden viral and bacterial threats in hospi- tals are controlled by extensive con- tamination control procedures and protective measures, such as sterili- zation. The same principles apply to ESD control. Nobody should ever handle, assemble or repair electronic assemblies without taking adequate protective measures against ESD.


Common Mistakes


Ionizers are poorly maintained or out of balance. If an ionizer is out of balance, instead of neutraliz- ing charges, it will produce primarily positive or negative ions. This results in placing an electrostatic charge on items that are not grounded, poten- tially discharging and causing ESD damage to nearby sensitive items. Appropriate tools should be


used to clean emitter pins and filters. A regular maintenance schedule should be created, which will extend the lifespan of ionizers tremendous- ly. Ionizers with “clean me” or “bal- ance” alarms should be considered. These will alert operators when


maintenance is required. According to the ESD TR20.20 handbook, “All ionization devices will


from: wrist straps, ESD footwear/ flooring and hip-to-cuff grounding. Acording to the ESD TR20.20


personal clothing worn under the garment.” ESD clothing loses its ESD


properties over time. It is an impor- tant part of the ESD control program to incorporate periodic checks of ESD garments.


No compliance verification plan or not checking ESD control products. Companies can invest thousands of dollars in purchasing and installing ESD control products but then waste their investment by never checking ESD items. This results in ESD equipment that is out of specification. Without the tools in place to


check their ESD items, companies may have no idea if they are actually working correctly. ESD products (like any other product) are subject to wear and tear. When investing in ESD control products, a compliance verification plan should be estab- lished. This ensures that ESD equip- ment is checked periodically and nec- essary test equipment is available. ANSI/ESD clause 7.4 states, “A


An effective ESD control plan includes proper grounding,


neutralizing insulators with ionizers and shielding ESD-sensitive items during transportation.


require periodic maintenance for proper operation. Maintenance inter- vals for ionizers vary widely, depend- ing on the type of ionization equip- ment and use environment. Critical cleanroom use will generally require more frequent attention. It is impor- tant to set up a routine schedule for ionizer service.”


ESD Garments are ungrounded. Operators wearing an ESD coat, without appropriate wrist straps or footwear, thinking they are properly grounded, is a common occurrence. Without proper electrical bonds to a grounding system, operators are not grounded. Every ESD garment needs to be


electrically bonded to the grounding system of the wearer. Otherwise it just acts as a floating conductor. There are a few options to choose


handbook, “After verifying that the garment has electrical conductivity through all panels, the garment should be electrically bonded to the grounding system of the wearer so as not act as a floating conductor. This can be accomplished by several means: 1. Ground the garment to the body through a wrist strap-direct connec- tion with an adapter. 2. Ground the garment through con- ductive wrist or heel cuffs in direct contact with the skin of a grounded operator. 3. Ground the garment through a typical separate ground cord, directly attached to an identified groundable point on the garment. 4. Garments should be worn with the front properly snapped or buttoned to avoid exposure of possible charge on


compliance verification plan shall be established to ensure the organiza- tion’s fulfillment of the requirements of the plan. Process monitoring (mea- surements) shall be conducted in accordance with a compliance verifi- cation plan that identifies the techni- cal requirements to be verified, the measurement limits and the frequen- cy at which those verifications shall occur. The compliance verification plan shall document the test meth- ods used for process monitoring and measurements. If the organization uses different test methods to replace those of this standard, the organiza- tion shall be able to show that the results achieved correlate with the referenced standards. Where test methods are devised for testing items not covered in this standard, these shall be adequately documented including corresponding test limits. Compli ance verification records shall be established and maintained to provide evidence of conformity to the technical requirements. The test


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