{"id":104,"date":"2008-12-19T17:10:22","date_gmt":"2008-12-19T22:10:22","guid":{"rendered":"http:\/\/www.esdpros.com\/?p=104"},"modified":"2008-12-19T17:10:22","modified_gmt":"2008-12-19T22:10:22","slug":"frequency-of-testing-esd-technical-elements-in-an-epa","status":"publish","type":"post","link":"https:\/\/www.gndzero.com\/blog\/frequency-of-testing-esd-technical-elements-in-an-epa\/","title":{"rendered":"Frequency of testing ESD Technical Elements in an EPA"},"content":{"rendered":"

Q<\/strong>:\u00a0 We have a number of carts, racks, and chairs in the clean room. When we do our weekly, monthly and semi-annual checks for ESD and grounding, do we do a statistical sample or do we check all of each item. Is there a standard that explains this?<\/p>\n

A<\/strong>:\u00a0 You ask a very valid question and it just so happens that I received a similar question on this not long ago.<\/p>\n

I wish there was one and only one ESD Bible that\u2019s all inclusive and complete; from design to audit. The ESD Association has the ANSI\/ESD S20.20-2007 document which gives us guidelines in establishing an ESD control program. But as far as a standard explaining when to audit each and every ESD technical element, I have yet to find a good source. The tables contained within 20.20 will give you \u201crequired limits\u201d for various technical elements, but not a frequency of when to audit or test these systems. Between JEDEC Standard 625-A Table 2 of page 9 and other sources, I\u2019ve put together these recommendations, but it\u2019s up to you to implement them and tailor them to your unique processes;<\/p>\n

Typical Facility Areas Requiring ESD Protection:
\n\u00b7 Receiving
\n\u00b7 Inspection
\n\u00b7 Stores and warehouses
\n\u00b7 Assembly
\n\u00b7 Test and Inspection
\n\u00b7 Research and Development
\n\u00b7 Packaging
\n\u00b7 Field Service Repair
\n\u00b7 Offices and Laboratories
\n\u00b7 Clean Rooms<\/p>\n

Elements of Effective Training Programs
\n1. Successful training programs cover all affected employees<\/p>\n

2. Effective training is comprehensive and consistent; Fundamentals of ESD, details of your facility\u2019s ESD Control Program, and each person\u2019s role.<\/p>\n

3. Use a variety of training tools and techniques; equipment product sheets, 20.20, etc.<\/p>\n

4. Test, certify and retrain; motivate and build employee pride and make this an ongoing process, provides opportunity for improved procedures, reminds and reinforces what they\u2019ve learned.<\/p>\n

5. Feedback, auditing, and measurement; use the tools you\u2019ve been given- review, audit, analyze, feedback, and improve. Audits can be internal or 3rd party.<\/p>\n

As far as Periodic Verification\/Testing, you should include these ESD Materials\/Equipment
\nA. Grounding\/Bonding Systems < 1.0\u2126 impedance for equipment gnd conductor and should be checked weekly-visual and quarterly for gnd continuity
\n< 25\u2126 to equip gnd from auxiliary ground
\n< 1.0E9\u2126 for Equipotential ground Per ANSI\/ESD S6.1-2005
\n< 2.0 \u2126 for tools and < 1.0 \u2126 for solder tip to ground, although this value can go to = 1.0E5\u2126 = 0.8E6\u2126 to 1.2E6\u2126 per ANSI\/ESD S1.1 Required to check daily prior to each shift minimum or use constant monitor<\/p>\n

C. Constant Monitors; Manufacturers specs\/User defined; check quarterly<\/p>\n

D. Footwear Method 1: <3.5E7\u2126 in combo with person, floor, footwear to gnd per STM97.1 or Method 2: <1.0E9\u2126 per 97.1 AND < 100 volts per 97.2 Required to check daily before each shift minimum<\/p>\n

E. Flooring and floor mats 2.5E4\u2126 to 1.0E6\u2126 for Static Conductive and 1.0E6 \u2126 to 1.0E9 \u2126 for Static Dissipative, check quarterly, inspect gnd continuity weekly **Note, I like being near ESD conductive for flooring and floor mats, 1.0E6 ohms to less than 1.0E8 ohms for bench mats\/work surfaces**<\/p>\n

F. Personnel grounding with Garment; groundable point to gnd <3.5E7 \u2126 per STM2.1, visual check daily<\/p>\n

G. Garments Sleeve to sleeve at 100 volts or auto ranging: Static Control < 1.0E11 \u2126
\nGroundable Static Control <1.0E9 \u2126, inspect after each wash; test per STM2.1<\/p>\n

H. Air Ionizers < +- 150 Volts per STM 3.1; check charge decay performance and balance to <35volts semiannually unless auto calibrating.<\/p>\n

I. Seating < 1.0E9 \u2126 per STM 12.1; check quarterly<\/p>\n

J. Mobile Equipment\/Carts\/Shelving < 1.0E9 \u2126 per S4.1; Quarterly<\/p>\n

K. Packaging; Manufacturers specs per S541, S11.31, etc.<\/p>\n

L. Awareness\/Signage; verification, User defined<\/p>\n

Special considerations:<\/p>\n

ESD carts racks and chairs being used in your EPA (ElectroStatic Discharge Protected Area) would obviously be used in conjunction with an ESD flooring system; albeit Static Conductive (2.5E4 \u2126 to 1.0E6 \u2126 from Point To Point and\/or Resistance to Ground) or Static Dissipative (1.0E6 \u2126 to 1.0E9 \u2126 PTP and\/or RTG) and that all personnel is utilizing the ESD flooring system by wearing ESD footwear as well.<\/p>\n

More needs to be said about shelving per ESD TR20.20-Handbook: shelving systems are frequently included as part of an ESD protected workstation and are used to store both packaged and unpackaged ESD sensitive products. If that is the case, they should be treated as an ESD worksurface and should be properly covered with the proper resistance matting or esd protective material, grounded, and free of unnecessary static generators. If you have processes at different steps within your EPA Cleanroom, then you should have all of the shelves properly covered and grounded or properly marked as such.<\/p>\n

Mobile equipment such as portable task carts, in-process storage carts, and mechanized skids that are used for heavier assemblies, can take advantage of the flooring system via ESD casters, drag chains (minimum of 12\u201d coverage on ESD flooring system recommended), and cable and ball assemblies. The various surfaces can be measured in combination with the ESD flooring system to earth ground for compliance to 20.20 standards.<\/p>\n

Seating. Another secondary grounding system that can take advantage of the ESD flooring system is seating. The resistance from a person seated in an ESD chair through the ESD flooring system to electrical ground should be less than 3.5E7 \u2126 if it is used as the \u201cprimary grounding source\u201d, or less than 1.0E9 \u2126 as measured per ANSI\/ESD STM 12.1 via ANSI\/ESD S20.20-2007. You can achieve this with an ESD chair with ESD casters or an ordinary task chair with the conductive Chair Cover with drag chain. Personnel would be expected to wear the proper clean room smock for proper contact with the seat and chair back. For non-clean room conditions, cotton shirt and denim jeans are sufficient if it\u2019s within personnel dress code.<\/p>\n

That\u2019s about all I can think of for now. Let me know if you have additional questions. It\u2019s good to see people incorporating this.<\/p>\n","protected":false},"excerpt":{"rendered":"

Q:\u00a0 We have a number of carts, racks, and chairs in the clean room. When we do our weekly, monthly and semi-annual checks for ESD and grounding, do we do a statistical sample or do we check all of each item. Is there a standard that explains this? A:\u00a0 You ask a very valid question […]<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[60,105,140,141],"class_list":["post-104","post","type-post","status-publish","format-standard","hentry","category-esd-compliance","tag-epa","tag-frequency","tag-technical-elements","tag-testing"],"_links":{"self":[{"href":"https:\/\/www.gndzero.com\/blog\/wp-json\/wp\/v2\/posts\/104","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.gndzero.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.gndzero.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.gndzero.com\/blog\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gndzero.com\/blog\/wp-json\/wp\/v2\/comments?post=104"}],"version-history":[{"count":0,"href":"https:\/\/www.gndzero.com\/blog\/wp-json\/wp\/v2\/posts\/104\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.gndzero.com\/blog\/wp-json\/wp\/v2\/media?parent=104"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.gndzero.com\/blog\/wp-json\/wp\/v2\/categories?post=104"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.gndzero.com\/blog\/wp-json\/wp\/v2\/tags?post=104"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}