The Museum of HP Calculators

HP Forum Archive 21

[ Return to Index | Top of Index ]

OT: Cal-Tex or "How to remove the lid of an old IC"?
Message #1 Posted by Joerg Woerner on 6 May 2012, 2:11 p.m.

Still puzzled about the manufacturer of the weird Unitrex 800K calculator chip and we decided to sacrifice one...

Short question: How to we remove the lid of a DIL package w/o destroying the chip?

Suggestions welcome.

Have a great week.

Regards, Joerg

      
Re: OT: Cal-Tex or "How to remove the lid of an old IC"?
Message #2 Posted by Frank Boehm (Germany) on 6 May 2012, 2:15 p.m.,
in response to message #1 by Joerg Woerner

I think a sharp knive will work out fine - at least that's how I did it before. If you trash your IC, I'll find another...

            
Re: OT: Cal-Tex or "How to remove the lid of an old IC"?
Message #3 Posted by Joerg Woerner on 6 May 2012, 2:20 p.m.,
in response to message #2 by Frank Boehm (Germany)

Frank,

Sounds great. We could trade the chip for a TI-88 ;-))

Dir noch einen schoenen Sonntag / Have a great Sunday.

Joerg

      
Re: OT: Cal-Tex or "How to remove the lid of an old IC"?
Message #4 Posted by Martin Paech on 6 May 2012, 2:23 p.m.,
in response to message #1 by Joerg Woerner

From experience, that could be a very risky task: In doubt ask Peter Nusser, cpu-galaxy.at.

"Nobody does it better..." Look and see!

http://www.cpu-galaxy.at/Article/Articles_startpage.htm

Martin

Edited: 6 May 2012, 2:26 p.m.

      
Re: OT: Cal-Tex or "How to remove the lid of an old IC"?
Message #5 Posted by Luiz C. Vieira (Brazil) on 6 May 2012, 6:25 p.m.,
in response to message #1 by Joerg Woerner

Hi.

I have seen some IC's being cut and have their lid removed (Martin's proposed link to www.cpu-galaxy.net in one of the follow-ups has some very good examples), but what are the odds of having a sealing resin compound glued to the lid that would destroy the chip if the lid is removed? Isn't there a way to check for solid contents with some modern scan technology prior to try to remove it? If the chips are rare and one can be sacrificed, why not to make sure it is done accordingly?

My thoughts, though.

Luiz (Brazil)

Edited: 6 May 2012, 6:27 p.m.

            
Re: OT: Cal-Tex or "How to remove the lid of an old IC"?
Message #6 Posted by Eric Smith on 6 May 2012, 10:39 p.m.,
in response to message #5 by Luiz C. Vieira (Brazil)

I've never yet heard of a metal-lid package that didn't have an open cavity containing the part. That's the reason the metal lid is necessary. If you seal it in resin, it doesn't need a metal lid.

            
The chip is not too rare.
Message #7 Posted by Frank Boehm (Germany) on 7 May 2012, 4:11 a.m.,
in response to message #5 by Luiz C. Vieira (Brazil)

I'm not sure if the value justifies a former non-destructive inspection - as long as you don't have you own x-ray equipment ;)

      
Re: OT: Cal-Tex or "How to remove the lid of an old IC"?
Message #8 Posted by robert rozee on 7 May 2012, 8:01 a.m.,
in response to message #1 by Joerg Woerner

if you can get the lid to tin (just with normal solder), then a hot soldering iron will heat it up sufficiently to melt any gold-based solder OR soften the resin that appears to be holding it in place.

a neat trick with 2-part epoxies (araldite) is to place the glued item in boiling water - the epoxy will (often) disintegrate.


[ Return to Index | Top of Index ]

Go back to the main exhibit hall