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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


ESD mats

Hany A. Salam

#8792

ESD mats | 27 October, 1999

Hello there: Currently we are building our own facility for producing electronic assemblies. I had a long discussion with my colleagues concerning the ESD mats surrounding the sensitive components areas such as the pick & place machines, rework & repair, etc. One of the suggested ideas was to use thin metal sheets in combination with ESD foot straps for the operators.

Now I ask if this is accepted technically or not. The reason for this question is the very high prices of the ESD mats.

Best regards. Hany A. Salam

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#8793

Re: ESD mats | 27 October, 1999

well... it might be cheaper. But I think it's a bad idea. First, your operators will hate you by the end of the day with their sore feet, not to mention lost productivity. Second, safety. Even if the plates are connected to ground through a resistor there are any number of ways that they could become connected directly to ground resulting in a dangerous safety condition. Third, what kind of metal? Steel will rust and aluminum will corrode and oxidise. Neither are very good for conductivity or appearance and I wouldn't like the particulates given off in my shop. How will you fasten them down so nobody trips? You mention rework and repair areas. Foot straps are not very effective for sit-down tasks. Better (and cheaper) to use wrist straps. I would pop for mats for stand up tasks. If you implement a rigorous maintenance and testing you probably could get away with a conductive floor finish for stand up tasks but it isn't reliable for that long. If you do go for wax, try to get one without a metals content to reduce disposal problems. Whatever you do, create written policies, enforce the policies and test the equipment. Search there archives for much more info on ESD/EOS prevention good luck - John Thorup

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Jeff Sanchez

#8794

Re: ESD mats | 27 October, 1999

Hany, John is right! How do I know cause I have a metal wire floor. I was faced with the same problem you are faced with now and the price was up there. I had one advantage, My floors where raised wood when we got the shop. This reduced the fatigue of the operators. I used 1/4 inch bird wire. Believe it or not it works great. We then hooked the resistor at the termination points and measured it. We stapeled it down and and added a seam.Yes it looks really back woods and I cringed at the idea of a customer walk through. We did get our walk through from a company that makes high end camaras. These guys did not take our aproach with a warm welcome which is what John was pointing out! But after they reviewed it they told us that it did in fact pass the standards and guidelines that where required. We got the job! Sometimes ya just gotta do with what ya got. All the benches where covered and that is a must but that floor thing is a b@#&h! I think it's a major pain to clean as well but if it means getting a job where I wouldn't have other wise, than any low cost headache is worth it. A few more bucks and the tiles are on there way.........Good luck. Jeff Sanchez

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#8795

Re: ESD mats | 28 October, 1999

Jeff: You are a "wild and crazy guy!!!" Dave F

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Bill Haynes

#8796

Re: ESD mats | 28 October, 1999

Hany, ESD mats, in my opinion, are very important. Why jepordize the quality of your product. We use sheets of stainless steel around all areas that are ESD sensitive and ground them to the machines. Of course they are no good unless the people standing on them have a foot strap on. I would also suggest purchasing a ESD tester for the foot straps to make sure they are good. Yes, the mats may cost a little up front but it beats lost sales because of parts getting zapped and the product not working.

good luck, bill

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Ron T

#8797

Re: ESD mats | 28 October, 1999

How are you going to ground the metal sheets? You certainly don't want to leave these hard grounded; you need to dissipate any static charge over time.

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