Looks like "step plating". Residue from the resist developer were not removed by the pattern plate Pre-clean,. Hence copper does not plate right away and you end up with low spots. Eventually it starts plating so you don't end up with a total etchout. Small amounts around the edges of pads (seen only under magnification & a horizontal light source) is not that uncommon. ENIG of course makes any defect look worse. However this is pretty gross by any standards. Could also be some type of etch resist breakdown, but doubt it.
Hope they are not ours!
Robert E. Welch
Senior Process Engineer
Moog Components Group
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
Sent: Wednesday, July 15, 2015 10:36 AM
To: [log in to unmask]
Subject: Re: [TN] MYSTRY DEFECT
Some kind of weird pattern plating process defect?
Light makes all defects of this type LOOK huge. IF the plating where the defects are is thinner than your specification for surface plating thickness, then it's rejectable. Measuring is easiest with a high resolution (>200X) optical microscope with a calibrated focus height readout. If used by a skilled operator, you can get a resolution of 3 microns or even a little better. If that's not good enough, you need to section and probably use SEM.
Wayne
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Wednesday, July 15, 2015 10:16 AM
To: [log in to unmask]
Subject: Re: [TN] MYSTRY DEFECT
Hi Ong Seet Leng,
I got your photos and have them posted now, the links are here:
https://urldefense.proofpoint.com/v2/url?u=http-3A__stevezeva.homestead.com_Mystery-5FDefect-5F1.jpg&d=AwICaQ&c=ByDrzdYw8tO08sJlHDO_Vg&r=LW2JrkDqJ9rzfIEkoxZO_Q&m=jV6Qtbo-FApi-4a8NyqLiVdC-eocoheTAn7TCwH0-ZQ&s=9cXwBtf2TlJi1ADXmcnJ5CqFruSEe4Wm0xxOaCT-0Lk&e=
https://urldefense.proofpoint.com/v2/url?u=http-3A__stevezeva.homestead.com_Mystery-5FDefect-5F2.jpg&d=AwICaQ&c=ByDrzdYw8tO08sJlHDO_Vg&r=LW2JrkDqJ9rzfIEkoxZO_Q&m=jV6Qtbo-FApi-4a8NyqLiVdC-eocoheTAn7TCwH0-ZQ&s=0c9kfnMi1Sy9OTIiPx0gJ2S1omgi-Ya2-hPd5umWKHc&e=
Looks like there was some sort of problem with the etch resist, can't say exactly what that was though. I definitely would be kicking these back to the vendor!
Steve
On Tue, Jul 14, 2015 at 2:15 AM, Ong Seet Leng <[log in to unmask]> wrote:
> Afternoon,
>
> I had checked a bare printed wiring board and attached a photograph on
> one of the defect found. I would like to seek advice from you gurus'
> out there on what to call this defect? For the life of me, I can't
> find the definition of it. Appreciate if someone can guide me. Thanks
> in advance.
>
> Regards,
> Ong Seet Leng
>
>
>
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