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Old 8th June 2011, 11:15 PM   #1
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Default What's wrong with this PCB

I know it's off topic but... can someone tell me what's wrong with this PCB? I know it's not supposed to look like this. It looks like some processes were screwed up during manufacturing. How come those soldering points that should be silver are brownish now? Did someone spill an acid over it?
thanks.
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Last edited by cobretti; 8th June 2011 at 11:36 PM.
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Old 8th June 2011, 11:24 PM   #2
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My guess is it is residue from organic water-soluble flux.
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Old 8th June 2011, 11:28 PM   #3
tomchr is offline tomchr  United States
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It's a bit hard to accurately tell the color from the .jpg image, but it looks to me like a typical dull immersion gold finish.

~Tom
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Old 8th June 2011, 11:40 PM   #4
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here is a different picture, hope you'll see it better
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Old 8th June 2011, 11:59 PM   #5
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I don't think it's a flux residue. The brownish color reminds me the temperature change when hardening and annealing (steel).
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Old 9th June 2011, 03:39 AM   #6
alexcp is offline alexcp  United States
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If the PCB was originally silver plated, which is a cheaper RoHS alternative to gold plating, then this is the way it would naturally look after some time in the open air. The brown stuff can easily be removed, and I believe it does not affect soldered points.
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Old 9th June 2011, 11:15 PM   #7
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Thanks for the answer. Guys, how many of you have seen hard drive from the bottom side gold plated? I have never. From what I can see, it looks to me that the original intention was to do everything silver-tin plated as it usually is on almost all PCB these days in mass production. I still try to find what process was screwed up because half of the board is silver and half is brownish. Thanks anyway.
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Old 10th June 2011, 01:43 AM   #8
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Default I would worry a bit

The PCB industry had problems with tin whiskers and they went to ENIG finish (gold). Your HDD pcb looks oxidized (not like my WD Caviar) but it usually means corrosive gasses (during reflow or use) or a chemical problem with the gold immersion.

I would worry a bit because the connector for the heads is often just pads on the other side of the PCB. Both sides of the PCB would have the oxide. Google a teardown on your drive make/model and check it out.
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Old 10th June 2011, 10:35 AM   #9
marce is offline marce  United Kingdom
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Does it clean of with isopropanol?
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Old 10th June 2011, 08:03 PM   #10
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No it doesn't clean with anything. I think :"prairiemystic" got it right. It's oxidized. I also have another WD caviar and that one is nice and silver clear.
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