++++++++++++++++++++++ Date: Fri, 14 Mar 2003 19:42:24 -0700 From: "James R. Duffey" To: Elecraft at mailman.qth.net, rondec at easystreet.com, rohre at arlut.utexas.edu Subject: [Elecraft] Humidity and ESD High humidity is not guaranty against electrostatic Damage. When I worked at Hughes Aircraft in LA, 2 miles form the ocean, we had mandatory ESD training oncew a year. George Bryan ran it. I took the course one rainy January day. With an ESD meter, Dr. George measured 500 V of static electricity from a tech putting on a non ESD treated lab jacket, and 900 V from putting an untreated fiberglass parts tray down on a formica lab table and raising it up. That made a believer out of me. High humidity is no assurance that ESD won't occur. About 10 years later, I relocated to New Mexico. Lots of static electricity here at any season. Now working for Maxwell, I had an engineer building a data acquisition system for me in San Diego. I visited him one day when the marine layer was in thick. The first thing I noticed was that there was no anti-static pad or ESD precautions on the bench. An interesting conversation followed: Me: "You don't have any antistatic protection here." Charlie: "We don't need it, the ocean is close by and it is very humid. Static Electricity has no chance here." Me: "What are you doing now?" Charlie:"Changing this latch that failed." Me: "Is it a CMOS part?" Charlie: "Yep." Me: "How did it fail?" Charlie: "I don't know, sometimes these things just fail, you know like infant mortality. It is easier to replace it." Me: "Do you think it could be ESD?" Charlie: "No, maybe in New Mexico, but like I said, it is too humid and we are too close to the ocean here." Me: "Get an anti-static pad and wrist straps." When my colleague came back from a visit to the home office several weeks later, he said that I had a reputation for being an ESD fanatic. Better safe than sorry. When working with ESD parts, use anti-static protection. Latent damage is possible; the part may fail long after it has been hit by a static discharge. - Dr. Megacycle KK6MC/5 ______________________ James R. Duffey KK6MC/5 Cedar Crest NM 87009 DM65 ++++++++++++++++++ Date: Fri, 14 Mar 2003 23:56:37 -0500 To: elecraft at mailman.qth.net From: Kevin Cozens Subject: Re: [Elecraft] Humidity and ESD At 07:42 PM 03/14/2003 -0700, you wrote: >Better safe than sorry. When working with ESD parts, use anti-static >protection. Latent damage is possible; the part may fail long after it has >been hit by a static discharge. - Dr. Megacycle KK6MC/5 Always a good policy to err on the side of caution. Some years ago I either read or was told that as little as 50V of static can cause damage. Just because you didn't feel a shock when you touch something it doesn't mean there was no static discharge. Cheers! Kevin. (http://www.interlog.com/~kcozens/) Owner of Elecraft K2 #2172 |"What are we going to do today, Borg?" E-mail:kcozens at interlog dot com|"Same thing we always do, Pinkutus: Packet:ve3syb at ve3yra.#con.on.ca.na| Try to assimilate the world!" #include | -Pinkutus & the Borg +++++++++++++++++ Reply-To: From: "Ron D'Eau Claire" To: Subject: RE: [Elecraft] Humidity and ESD Date: Sat, 15 Mar 2003 15:59:41 -0800 Today a package arrived from Mouser. One of the things inside were some packages of common rectifier diodes. What I noticed was that the seal on the packets read "ATTENTION! OBSERVE PRECAUTIONS WHEN HANDLING ELECTROSTATIC SENSITIVE DEVICES". True enough. But that doesn't mean that the contents of those packages are "electrostatic sensitive" by any normal definition of the term. Oh, I guess if I'm hit with lightning while holding the package, neither I or the diodes might be much good afterwards. My point is that manufacturers and distributors are labeling many things that we'd never have considered sensitive it the past. It helps mask those items (like IC's with unprotected CMOS gates at the inputs) that really ARE sensitive. Because of that we must either be aware of what is or is not sensitive, or take extreme precautions about everything. The latter may work, but it's sort of like wearing a crash helmet when sitting on the couch. Ron AC7AC K2 # 1289 ++++++++++++++++++ From: "Don Brown" To: , Subject: Re: [Elecraft] Humidity and ESD Date: Sat, 15 Mar 2003 18:26:08 -0600 A few years ago (15?) I ran the engineering department of a semiconductor burn in lab in Dallas. I had to implement an anti-static program. Wrist straps, mats, chairs with metal fibers in the fabric with little drag chains on the floor and special antistatic floor wax. The operators even wore smocks with stainless steel thread woven into them. The shipping department only had antistatic bags and labels. When something is packaged up the shipping clerk didn't know anything about static sensitive parts so everything went into a static shielding bag with static labels because that's all she had to use for packaging. I think that is what is going on here with Mouser and other suppliers. We burned in mostly 2N2222 and 2N2907 (by the millions) in the military TO18 package. Not normally considered static sensitive but we also burned in CMOS parts and FET's so everything got lumped into the same category. I get resistors and capacitors shipped in antistatic bags with labels from FAI Electronics! Don Brown ----- Original Message ----- From: "Ron D'Eau Claire" To: Sent: Saturday, March 15, 2003 5:59 PM Subject: RE: [Elecraft] Humidity and ESD > Today a package arrived from Mouser. One of the things inside were some > packages of common rectifier diodes. > > What I noticed was that the seal on the packets read "ATTENTION! OBSERVE > PRECAUTIONS WHEN HANDLING ELECTROSTATIC SENSITIVE DEVICES". +++++++++++++++++++ From: "Don Brown" To: "Steve & Anne Ray" , "Elecraft" , Subject: Re: [Elecraft] Parts Storage Date: Sat, 22 Mar 2003 10:06:23 -0600 Hi I'm a little surprised after all the discussion about static problems the last few weeks that people would not realize that styrofoam blocks and plastic boxes are the worst possible thing you can use to store electronic parts in. The static fields that can build up on a styrofoam block can reach up into the 10's of Kilo volts. Even if the parts you are storing are not static sensitive just having such materials around the work bench is not a good idea. Taping the parts to a sheet of paper is also not wise. I have seen a demo of a strip of scotch tape after removing from the roll can have several Kilo volts on the tape. I leave the parts in the antistatic bags until ready to use or inventory and place them into an anti static tray or metal tray. I always ground myself to the tray before touching the part. Don Brown KD5NDB +++++++++++++++++