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lexx21
Joined: 10 Oct 2008
Posts: 119
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| Posted: Sat Jan 09, 2010 3:32 pm Post subject: |
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I used to work for a telecom equipment manufacturer many moons ago. Anyway, it was during the winter and cold air was blowing in constantly across one of these industrial throw rugs (the kind to keep you from slipping when you walk in the door). I walked across the rug on the way to the bathroom and across it again on the way back. I walked up to a piece of equipment that I was working on and the static discharge was so intense it hurt my arm all the way to the elbow. I was wearing static grounding straps for my shoes at the time and they had tested as good at the start of my shift.
Anyway, I ended up blowing out $200k worth of equipment with that one static blast. The equipment was powered up and running at the time and was very well grounded, but still ended up getting fried all he way back to the power supply.
That incident made me a believer in ESD protection considering I was supposedly grounded as was the equipment itself.
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westom
Joined: 14 Dec 2009
Posts: 56
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| Posted: Sat Jan 09, 2010 5:34 pm Post subject: |
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| lexx21 wrote: | | That incident made me a believer in ESD protection considering I was supposedly grounded as was the equipment itself. |
Being grounded does not solve problems. Grounded equipment can still be easily damaged. Grounding so that a finger tip is electrically connected to the bottom of shoes is protection. Grounded equipment can still be damaged if the fingertip touches that equipment. Then a static discharge current goes through electronics, then out via the equipment ground, then completes the current to shoe bottoms. Grounding equipment does not necessarily provide protection. Grounding out the charge (from fingertip to shoe bottom) is protection.
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Ile
Joined: 09 Mar 2006
Posts: 1491
Location: Jyväskylä, Finland
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| Posted: Mon Jan 11, 2010 5:58 pm Post subject: |
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Found this from my scopes service manual.
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westom
Joined: 14 Dec 2009
Posts: 56
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| Posted: Mon Jan 11, 2010 6:30 pm Post subject: |
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| Ile wrote: | | Found this from my scopes service manual. |
Which defines semiconductors limited to a few hundred volts. Meanwhile, view the 1st page of a semiconductor datasheet.
http://datasheets.maxim-ic.com/en/ds/MAX1487E-MAX491E.pdf
These CMOS parts repeatedly are defined by the phrase "+-15kV ESD-Protected".
Risk must be determined by the individual part and how it is integrated into a larger system.
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macgyver655
Joined: 22 Aug 2007
Posts: 8508
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| Posted: Mon Jan 11, 2010 8:14 pm Post subject: |
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Hmmmmmmmmmmmmmmmmmmmmm............................. 
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