Last word on this subject. I finally got a copy of EN 61340-5-1. Paragraph 5.2.1 "General" says: "Specific ESD protective items when used within an EPA (ESD protected area) shall have the characteristics described in 5.2.2 to 5.2.11..." Note the words "when used". So this document does not require use of conductive chairs, or clothing, or flooring. This is borne out elsewhere in the document, which says for example in Paragraph 5.5: "The primary means of grounding personnel shall normally be by a wrist strap connected to an EBP. When the use of a wrist strap system is impractical, the floor (see 5.2.3 and Table 1) and footwear (see 5.2.8) shall be the primary means of ESD control. When used, garments in accordance with 5.2.5 shall be worn and shall be properly fastened at all times." -Joe -----Original Message----- From: Gene Felder [mailto:[log in to unmask]] Sent: Tuesday, March 22, 2005 12:00 PM To: 'TechNet E-Mail Forum'; Kane, Joseph E (US SSA) Subject: RE: [TN] ESD Issue - non ESD Chairs on Manufacturing Floor I just review a Sanmina - SCI document from Northern California that referenced IEC EN 61340-5-1. This document was British Standard. My copy has IEC 61340-5-1. My understanding that it was adopted as the European Norm so is now EN 61340-5-1. The title of the document is "Electrostatics, Protection of electronic devices from electrostatic phenomena - General requirements." The "User Guide" is -2. We go to market in Europe using our Charleswater brand and we use EN 61340-5-1. It is very similar to ANSI/ESD S20.20. I was surprised when I looked up yesterday and read the "shall be" regarding Seating. I am told that SWAG 50% of users in Europe use ESD chairs. Ron Gibson of Celestica and the ESD Association is the Canadian representative to ISO; he has said that before too long Europe is likely to adopt S20.20. 1. Does the 61340 spec also require grounded floor? If not, each chair would have to be grounded with a wire. Nasty, cumbersome, and a heck of a tripping hazard. Yes, per EN 61340-5-1 section 5.2.3 Floors "All floor surfaces shall have a surface-to-EPA ground resistance in accordance with table 1." [same as S20.20 < 1 x 10^9 ohms]. 2. Does the spec also require conductive clothing? I don't see how else to make electrical contact between the person and the grounded chair. Yes, per EN 61340-5-1 section 5.2.5 Garments "Coats, jackets, smocks and overalls shall completely cover all clothing in the area of the arms and torso. There shall be electrical continuity between all parts of the garment. Garments shall have characteristics on the outward facing surface in accordance with table 1. [Rp =/< 1 x 10^12 ohms vs. S20.20 1 X 10^5 to 1x10^11 ohms] Garments complying with ESD requirements shall be clearly marked." And is it mandated that such clothing cover one's seat when seated? I find no mention regarding this 3. I don't buy the argument that the chair should be grounded because it might be improperly used as a table. By this logic, we should cover every horizontal surface in the shop. If there is sufficient discipline on the shop floor, it would be costly overkill. ESD Association deals with this stating per ESD Protected Workstations ESD-ADV53.1 Electrical Requirements, "Workstation elements shall be connected to, and maintain electrical continuity to, the common point ground as follows: Surfaces of shelves and drawers intended to be used for unprotected ESD sensitive devices - Resistance: Between 1 x 10^6 ohms and 1 x 10^9 ohms." 4. I don't think the reference to two grounded feet means the operator's feet. I believe that conductive heel straps or footwear are designed to meet grounding requirements with the person's full weight on them. If the individual is seated, there is insufficient contact pressure with the floor to make a good ground path. That is my reading "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" is referring to the chair's feet. When seated, the operator should wear a wrist strap. Right. Per EN 61340-5-2 section 5.2.4 "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. S20.20 is even stronger included in section 6.2.2.1. " When personnel are seated at ESD protective workstations, they shall be connected to the common point ground via a wrist strap system." Gene Felder [log in to unmask] -----Original Message----- From: Kane, Joseph E (US SSA) [SMTP:[log in to unmask]] Sent: Tuesday, March 22, 2005 6:08 AM To: [log in to unmask] Subject: Re: [TN] ESD Issue - non ESD Chairs on Manufacturing Floor We don't have grounded chairs either. In my American parochialism, I'd never heard of the 61340 specs, and none of our customers have ever mentioned them either. Still, I'm going to order some copies and have a look. But I'm suspicious of such a "requirement". 1. Does the 61340 spec also require grounded floor? If not, each chair would have to be grounded with a wire. Nasty, cumbersome, and a heck of a tripping hazard. 2. Does the spec also require conductive clothing? I don't see how else to make electrical contact between the person and the grounded chair. And is it mandated that such clothing cover one's seat when seated? 3. I don't buy the argument that the chair should be grounded because it might be improperly used as a table. By this logic, we should cover every horizontal surface in the shop. 4. I don't think the reference to two grounded feet means the operator's feet. I believe that conductive heel straps or footwear are designed to meet grounding requirements with the person's full weight on them. If the individual is seated, there is insufficient contact pressure with the floor to make a good ground path. When seated, the operator should wear a wrist strap. Bottom line, if the person is grounded through a proper wrist strap, it shouldn't matter what they are sitting on. We might get an argument from someone who is selling chairs. Joe Kane BAE SYSTEMS Platform Solutions Johnson City, NY -----Original Message----- From: Gene Felder [mailto:[log in to unmask]] Sent: Monday, March 21, 2005 6:14 PM To: [log in to unmask] Subject: Re: [TN] ESD Issue - non ESD Chairs on Manufacturing Floor 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------