Once upon a time someone posted that they had found something that really brought out the numbers etc on otherwise difficult to read ICs. Unfortunately I didn't save the post, or the info in it. Anybody have any ideas on what this might have been, or how to read those invisible numbers/letters? Some ICs are no problem, but others... I am getting really tired of trying to get the light just right and halfway guessing at what they say.
TIA,
Dave
-- http://www.doneganoptical.com/optivisor.php JF
Thanks, but I already have a magnifier that will do the job if I choose to use it. Would rather have something that does the job once and for all on each unreadable IC. I'll try google again...
Dave
Nigel Cook mentioned teflon tape:
YES! That was it! THANK YOU!
I had some teflon tape handy, and tried it out, and it works like magic. For me, laying a strip of tape over the IC of intersest and rubing fairly lightly with the ball of my index finger brought the letters and numbers, including the manufacturers logo (which I didn't even know was there) out like magic. Peeling the tape back off, the letters and numbers were still there, and highly visible. Thank you again. I have another trick in my toolkit now.
Dave
Follow up-on some ICs you have to rub with the back of a nail or other rounded, smooth surface, to get an image of the letters/numbers in the teflon tape. Then the image is in the tape, and not on the IC, like the original poster (Nigel Cook) said. But it still works! Damn.
Thanks again,
Dave
high brightness LEDS and low angle lighting are two tricks I use. a magnifier helps too.
Bye. Jasen
That's a great tip. I have to try that sometime. Thanks.
Tom
from one of my tips files, off URL below
How to read unreadable IC/transistor lettering Yes, just like magic. I could not read 3 of the 5 characters on a heat damaged TOP66 power transistor. I wondered if a sort of "brass rubbing" would work. I just happened to have some plummer's PTFE tape to hand ( nominal 0.05 to
0.08 mm thick). Laid a piece over the power tranny, rubbed with a finger nail, and the missing characters came up like magic. As the characters remained on the PTFE, as an image , I realised you could use this technique to read IC lettering where it is imppossible to read, because of constrictions and inability to introduce an inspection mirror or even just where you cannot get the illumination at just the right angle to read. You need access space enough to introduce a piece of PTFE and then rub it with the wooden end of a small artist's brush, or similar, wrapped in some of the PTFE, so it rubs easily without dragging. Don't rub too firmly because you want the relief print to show as clear and the rest of the PTFE becoming translucent rather than the original white. Remove and read with a backlight or against something matt black. Maybe a couple of attempts to get a clear image in all parts of the label. May even be worth trying on reverse-engineering-proofed, rubbed off, IC lettering. Useful for indistinct moulding logos / lettering etc on small plastic parts, gives some contrast.-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
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