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up vote 18 down vote favorite
5

I find very difficult to read part numbers. I haven't figured out how which kind the ideal amount of light and inclination would help me.

I also wonder why chipmakers don't paint the numbers in white for a better contrast.

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11  
because 95-99% of parts are sold on reels with bar codes that just get inserted into pick in place machines. Labeling cost increases for the tiny fraction of parts that actually get handled by a human isn't worth it. – Mark Oct 14 '10 at 1:58
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I think most markings now are done by laser engraving, "burning" the epoxy package to make the brownish print, not sure though. – Nick T Oct 14 '10 at 4:48
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@Mark if that's the case why bother to print at all? – Jader Dias Oct 14 '10 at 11:30
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Because people can still read the markings if they need to. Yeah, it's hard, but far from impossible. – Nick T Oct 14 '10 at 21:00
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as Nick said its still "nice to have" for debugging and such. A laser engraver is a really, really cheap addition to the fab process compared to everything else and has zero ongoing costs with the exception of maintenance which probably just goes on as part of the overall system maintenance. White ink, as cheap as it sounds, would be really expensive when talking about parts that often cost pennies to produce, not to mention that an ink stamper that can handle any sort of graphics is WAY more expensive than a laser engraver. – Mark Oct 15 '10 at 1:00

7 Answers

up vote 36 down vote accepted

1. Clean up the text with a cotton swab dipped in rubbing alcohol.

alt text

2. Wait for the alcohol to evaporate and rub yellow or white chalk on markings.

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3. Wipe gently with a cotton swab and bingo!

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Source (in Portuguese): http://www.piclistbr.org/paginas.php?fname=%20dicas.htm%20&autor=%2009/2010%20-%20Luciano%20Sturaro

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4  
+1 for using Microchip parts! (And a good example!) – mjh2007 Oct 20 '10 at 19:05
-1 I am allergic to chalk. – kinokijuf Feb 7 '12 at 18:09
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@kinokijuf not necessary. – Daniel Grillo Feb 7 '12 at 23:36
@DanielGrillo I know it is not necessary to be allergic to chalk. – kinokijuf Feb 10 '12 at 13:33
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@kinokijuf I don't think your reason is a good one to down-vote my answer. I suggest you put a better answer for allergic. – Daniel Grillo Feb 10 '12 at 17:42
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up vote 13 down vote

Use a 10x loupe, very handy.

Occasionally some markings might be illegible after soldering and splattering some flux on them, so flux cleaner can help there.

Sometimes you can change the contrast by wiping the markings with your fingers; the skin oils can change the reflectivity to make it easier (or more difficult) to read.

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1  
Yeah, wiping the part with fingers can also remove flux residues (if it was desoldered from somewhere, which is the most frequent, for me, case when I need to recognize the part name). – whitequark Oct 14 '10 at 7:52
I use magnifying lamp, but the idea is same. I found that a quick rub with alcohol helps a lot. I have not tried, but theoretically a swipe with white chalk marks the rough surface created by the labeling and makes it easily readable :) – csadam Oct 14 '10 at 10:20
Flux can also be scraped off with a knife, and wiping the markings with spit can also help. >.< It even helps with chips that have had the numbers lazily scraped off, strangely enough. – endolith Oct 14 '10 at 13:52
up vote 5 down vote

It sounds obvious, but have you tried a magnifying glass? I always use one when trying to read part numbers.

Once I've done that, I usually print out a sticky label with the same information and stick it to the part.

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up vote 5 down vote

Get an LED torch with blue or clear/blueish LEDs, it works well for highlighting the text on chips - and it's handy to have while rummaging through the dark depths of the parts cupboard!

I rarely have to break out a magnifying glass, unless the print has started to rub off - bad design if you ask me, I've got a load of old 555 timers and 386 amps that are hard to tell apart as there's barely enough print visible to distinguish them.

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1  
Also, shining the light sideways rather than head on tends to help a lot. – Yann Vernier Oct 14 '10 at 14:59
up vote 4 down vote

I use a USB microscope with built in LED lights.

It is very useful for reading part numbers, but also comes in handy when reading values of resistors and small caps. I'm not sure on the magnification range, but I think it's from 5x to 50x. Around 10x-15x works well for reading part numbers.

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I'll second that, I use a cheapo clear/blue LED torch, it works a treat, I've got magnifying glasses but the torch is normally enough – Jim Oct 14 '10 at 10:04
up vote 3 down vote

I usually keep my digital camera with me when I'm working on stuff for this exact purpose. Put it in Macro mode, play with the flash settings as required and take the photo at an angle between 30 and 45 degrees from board level. Not only will the part numbers be plain as day - and you can zoom in for more detail - but the photos tend to look pretty awesome as well.

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it worked with my cellphone camera as well! Thank you! – Jader Dias Oct 26 '10 at 21:43
up vote 1 down vote

The reason it's often hard to read is that the part number is often lasered, not printed. (You wouldn't think manufacturers are idiotic enough to print dark gray on black, would you?)
Though a scanner may be more involved than a magnifier glass, I find that the lighting from my scanner makes the marking very clear, even when lasered. And you also get a higher magnification than any magnifier glass will give you.

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