Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site rosevax.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!ihnp4!stolaf!umn-cs!mmm!rosevax!hogan From: hogan@rosevax.UUCP (Andy Hogan) Newsgroups: net.micro.mac Subject: Re: RAM ugrades (static damage) Message-ID: <233@rosevax.UUCP> Date: Wed, 6-Nov-85 18:03:39 EST Article-I.D.: rosevax.233 Posted: Wed Nov 6 18:03:39 1985 Date-Received: Sun, 10-Nov-85 09:51:47 EST References: <1058@decwrl.UUCP> <27800002@ada-uts.UUCP> Organization: Rosemount Inc., Eden Prairie, MN Lines: 41 >> 5) RAM chips are easily damaged by static, and most users don't know >> how to properly ground themselves, the memory board, and the RAM >> chips while installing the chips. > >I personally think this static business gets blown out of proportion. >I've handled A LOT of 256k DRAMs without blowing ONE, and I don't take >any elaborate precautions - I just don't do anything blatantly stupid >(like work in a polyester shirt under a wool sweater). There is a widespread but completely mistaken understanding of ESD (static) damage to integrated circuits which says it is an all-or-nothing proposition. You can cause significant damage to an IC by static without "blowing" it completely. This damage takes the form of altered dynamic or static electrical performance (ie, input current, output current, i/o impedance, speed, etc.) and fairly often does not IMMEDIATELY affect the operation of the circuit. However, such damage has been shown to significantly shorten the useful lifetime of the IC. So it is impossible to tell, immediately after installing an IC in a circuit, whether it has been damaged by ESD or not. Also, the word "easily" in the first post is a relative term. 256K RAMs are indeed "easily" damaged with respect to certain other technologies, such as small-scale TTL chips. TTL is not destroyed by static until the applied charge comes from a source of a few kilovolts, whereas a CMOS RAM can be utterly destroyed by a source of less than one KV. Damaged-but-not-destroyed levels show roughly the same magnitude difference. Any system which prevents the buildup of a static field lower than damage levels is sufficient. The choice of prevention measures is an economic one. For one person, with one machine, careful handling, humidification and wearing cotton clothes may be enough. For more than one, you have to make a judgement. We tend to install our own (cheap) chips in PCs here because we have workstations that are available for such occasional use and that are fully protected, but this equipment is moderately expensive, and I doubt we would buy much of it just for our PCs. However, good grounding wrist straps can be had for $15--20 and that cost is easily justified. -- Andy Hogan Rosemount, Inc. Mpls MN path: ...ihnp4!stolaf!umn-cs!mmm!rosevax!hogan Working is not a synonym for Quality.