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Path: utzoo!mnetor!uunet!husc6!cmcl2!brl-adm!umd5!purdue!i.cc.purdue.edu!j.cc.purdue.edu!pur-ee!iuvax!inuxc!ihnp4!ihlpf!straka
From: straka@ihlpf.ATT.COM (Straka)
Newsgroups: rec.ham-radio,sci.electronics
Subject: Re: build-it-yourself EPROM erasers
Message-ID: <3709@ihlpf.ATT.COM>
Date: 16 Feb 88 17:46:49 GMT
References: <8802091255.AA23298@ucbvax.Berkeley.EDU> <12@ucsd.EDU> <41487@sun.uucp>
Reply-To: straka@ihlpf.UUCP (55223-Straka,R.J.)
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 25

In article <41487@sun.uucp> bobc@sun.UUCP (Bob Clark) writes:
>In article <12@ucsd.EDU> brian@ucsd.edu (Brian Kantor) writes:
>A few details:
>	Most EPROMs have a sensititity to a specific wavelength,
>	e.g. 253.7 nanometers for the TI TMS2732A.

Not really true.  253.7 nanometers just happens to be the primary wavelength
of the short-wave UV emitted by the typical lamps used for this application.

What this spec really means is that you can't use long-wave UV lamps (like
black lights, or mercury-vapor sun lamps) to do the job.  It also means that
you can't put ordinary glass or plastic in the light path either.  Only
special materials, such as fused quartz or some boro-silicate glasses have
the necessary transmissivity at that particular wavelength.

As for protection from light as to the erasing of your data, unless the EPROM
is marginal, the danger from typical light sources is grossly exaggerated by
most people.  When I was MAKING EPROMS back about 10 years ago (w/ Nat'l
Semi), once we put a THIN coating of polyimide on the chip as a contamination
barrier.  You could NEVER erase the data.  Same thing with Nitride
passivation.
-- 
Rich Straka     ihnp4!ihlpf!straka

Advice for the day: "MSDOS - just say no."