Per ANSI/ESD S20.20 Paragraph 6.2.2.1 Personnel Grounding Requirement "All personnel shall be bonded or electrically connected to ground or contrived ground when handling ESD sensitive items. When personnel are seated at ESD protective workstations, they shall be connected to the common point ground via a wrist strap system." ESD protective Seating is an optional implementing process per Table 1of ANSI/ESD S20.20; if used the minimum recommended technical requirement range is < 1 x 10^9 ohms. Included in the ESD Handbook TR20.20 section 5.3.5 is Static Protective Seating "As mentioned in the floor materials section of this handbook, the principle cause of static electricity in the workplace is cited as the movement of people and materials. This routine movement, particularly from a person seated in a chair or movement of the chair itself across the floor, can generate significant voltages. This section covers the use of seating in an ESD protected area for dissipation of charge. Although not required in ANSI/ESD S20.20 as a primary means of grounding personnel in the workplace, the use of chairs that meet resistive requirements from the seat contact surface to the castors or leg ends, may be an effective means of grounding personnel if a reliable method can be found to bond personnel to the chair. In addition, if the chair is used to connect personnel to ground than the maximum resistance to ground from the person through the chair and flooring system should be less than 35 megohms." However, it is mandated per EN 61340-5-1. Per section 5.2.4 Seating "The resistance from all areas of seating which may have human body contact when in normal use, to either a floor contact point or a groundable point, shall be as specified in table 1. [Rg =/< 1 x 10^10 ohms] When the floor is used as part of a grounding system, a minimum of two wheels or two feet shall provide a path to EPA ground." Its EN 61340-5-2 User Guide states: 5.2.4 Seating "It is important that low charging and grounded seating is used, as although seating should never be used as a primary means of grounding there are occasions where, through human error, equipment breakdown or bad design it can provide an important resistive path to ground. Although not recommended, in some EPA seats may be used as impromptu working surfaces or storage surfaces. If nonconforming seating is used then ESIDS may be damaged in this way. Where grounded, if footwear is used rather than wrist straps, when seated, many operators will spend periods when footwear is not in contact with the ground. Charges and potential can build up where there is no path to ground. In this case, a path may be provided through the garments (see 5.2.5), provided they are in contact with the seating. It should be emphasized that, where operators are seated, a wrist strap approach should be used and seating should form a secondary means of discharge. In the event that an ESID coordinator should decide that there is no suitable alternative to using seating as the primary grounding approach, resistance to ground should comply with the same requirements as wrist strap systems, or for flooring and footwear (i.e. 750 kQ to 35 MQ) (see 5.2.8). Seats in compliance with IEC 61340-5-1 should carry suitable labels (see clause 4) to help with identification. It is permissible for those parts of seats which are unlikely to come into contact with the body or with ESIDS, for example the underside of the seat, to be made of non-compliant materials." Gene Felder [log in to unmask] -----Original Message----- From: Dale Ritzen [SMTP:[log in to unmask]] Sent: Monday, March 21, 2005 2:53 PM To: [log in to unmask] Subject: [TN] ESD Issue - non ESD Chairs on Manufacturing Floor A sister company of ours has just undergone an ESD audit by one of their customers. During the audit, they were cited for allowing non ESD chairs (i.e. no drag chains and/or conductive wheels/legs) in the manufacturing areas. I looked in IPC-A-610, in section 3.2 (ESD/EOS Safe Workstation) and find no reference to non-ESD chair use. Simply put, if a solder operator, assembler, etc. is seated in a non ESD chair, but wearing heel straps (on a dissipative floor) and is jumpered to a grounded jack via a wrist strap my take is that they are sufficiently grounded to perform their work. I have never had any external ESD audit fail for this reason. Anyone else have any experience with this type of call? I don't have a copy of ESD S2020 so I can't refer to it for help in this case. Thanks! Dale Ritzen, CQA Quality Manager Austin Manufacturing Services --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------