What's wrong with this PCB

cobretti · 11:36 PM

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.

sofaspud · 8th June 2011, 11:24 PM

My guess is it is residue from organic water-soluble flux.

tomchr · 8th June 2011, 11:28 PM

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

cobretti · 8th June 2011, 11:40 PM

here is a different picture, hope you'll see it better

cobretti · 8th June 2011, 11:59 PM

I don't think it's a flux residue. The brownish color reminds me the temperature change when hardening and annealing (steel).

alexcp · 9th June 2011, 03:39 AM

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.

cobretti · 9th June 2011, 11:15 PM

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.

prairiemystic · 10th June 2011, 01:43 AM

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.

marce · 10th June 2011, 10:35 AM

Does it clean of with isopropanol?

cobretti · 10th June 2011, 08:03 PM

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.

8th June 2011, 11:24 PM	#2
sofaspud diyAudio Member Join Date: Nov 2005 Location: San Antonio TX	My guess is it is residue from organic water-soluble flux. __________________ It is error only, and not truth, that shrinks from enquiry. - Thomas Paine

10th June 2011, 01:43 AM	#8
prairiemystic diyAudio Member Join Date: Jul 2004 Location: Edmonton, AB Canada	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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8th June 2011, 11:28 PM	#3
tomchr diyAudio Member Join Date: Feb 2009 Location: Greater Seattle Area	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

8th June 2011, 11:59 PM	#5
cobretti diyAudio Member Join Date: Feb 2011 Location: Taxachusetts	I don't think it's a flux residue. The brownish color reminds me the temperature change when hardening and annealing (steel).

9th June 2011, 03:39 AM	#6
alexcp diyAudio Member Join Date: Jun 2009 Location: Florida Blog Entries: 28	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.

9th June 2011, 11:15 PM	#7
cobretti diyAudio Member Join Date: Feb 2011 Location: Taxachusetts	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.

10th June 2011, 10:35 AM	#9
marce diyAudio Member Join Date: Jun 2007 Location: Blackburn, Lancs	Does it clean of with isopropanol?

10th June 2011, 08:03 PM	#10
cobretti diyAudio Member Join Date: Feb 2011 Location: Taxachusetts	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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