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Today I received some PCBs I ordered, and they look like they are missing the gold from the ENIG process in some areas. Am I correct? What is the cause, and should I be concerned? They seem to still be conductive, but I am worried about in field failures and what I can't see, which is under the solder mask.

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    \$\begingroup\$ Did you try scraping off the grey stuff to see if there is gold underneath? Regardless of what it is, this is an issue that you should take up with the manufacturer because their processes are poor. This could create problems for the assembly processes because the solder might not stick. But we can't tell you because we aren't holding the PCB's in our hand, its your call: be cognizant. \$\endgroup\$
    – Voltage Spike ♦
    Commented Nov 3, 2016 at 21:46
  • \$\begingroup\$ I did try scraping it, and neither the grey or the gold material will come off. I am going to contact the manufacturer. \$\endgroup\$
    – user1080943
    Commented Nov 4, 2016 at 0:33
  • \$\begingroup\$ I like the ENIG vs HASL or others but it may be harder to control. there are many different ENIG processes. \$\endgroup\$
    – D.A.S.
    Commented Nov 4, 2016 at 0:46

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These gold skip-plating anomalies appear to be exposing a immersion Ni layer.

Test for high humidity temp corrosion and solderability and complain if correction required. Send back photos at least.

It may be insufficient rinsing between Cu microetch and catalyst ... or over-dip/rinsing between catalyst and EN..

just a guess or a SWAG

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  • \$\begingroup\$ sorry about the echo.. mouse button has contact bounce now.. (solder joint?) needs to be fixed. \$\endgroup\$
    – D.A.S.
    Commented Nov 4, 2016 at 0:31
  • \$\begingroup\$ I agree. At a minimum, it is not to spec. I am going to contact the manufacturer. \$\endgroup\$
    – user1080943
    Commented Nov 4, 2016 at 0:35

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