If they've not applied the finish they should be able to gently remove the
ink with a razor. Make sure they use caution to not gouge the copper
however.
On areas where not contact is made (i.e. vias) I would leave those areas
alone.
If it is only affecting test points, and not solderable areas, and the ink
is near the pad edge it also may be better to do nothing. The key factor of
course that the test probe has sufficient space to make good contact.
It may be a case where their software did not clip the symbol away from the
vias as it did not recognize them as component areas. I would certainly ask
them for the results of their thorough investigation of how this occurred.
Franklin
-----Original Message-----
From: Black, Paul [mailto:[log in to unmask]]
Sent: Tuesday, May 16, 2006 8:16 AM
To: TechNet E-Mail Forum; Franklin D Asbell
Subject: RE: [TN] Silkscreen on pads
Hi Franklin,
I am trying to find out from the supplier how many pads are affected. Since
I sent out the original posting, they have attached a picture of the board,
and from what I can see, all of the affected pads are vias that may also
double as test points, but it is a double-sided board and they only included
a picture of one side (I am going to request more detailed info, but they
are in Taiwan, so it will take another day before I receive an answer). It
looks like there may be about 30 of these via/test points, but so far I
don't see any component pads that are affected. Looking at the picture, the
final finish hasn't been applied yet (it will be ImAg). The silkscreen is on
bare copper. The assembly process doesn't use wave solder. It is almost all
reflow, with a few hand installed components. So, you think that I can just
have them remove it with a razor knife and then apply the final finish?
Thank you,
Paul Black
Manufacturing Engineer
Kronos
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Franklin D Asbell
Sent: Tuesday, May 16, 2006 8:59 AM
To: [log in to unmask]
Subject: Re: [TN] Silkscreen on pads
How many pads on the 1000 boards are affected? What is the final finish?
It could be as easy as returning them to the supplier, have them remove the
ink with a razor knife and recoat the boards covering any exposed copper.
If they are using lead free HASL and you're using a wave solder process,
and, the ink is not on the pads to a great degree it may not present any
problems.
Franklin
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Black, Paul
Sent: Tuesday, May 16, 2006 7:46 AM
To: [log in to unmask]
Subject: [TN] Silkscreen on pads
Hi Fellow TechNetters,
I am expecting a fabbed board for our first leadfree production build next
month and have just been informed by the supplier that the artwork contained
silkscreen on quite a few of the solderable SMT pads. They didn't catch it
in time, so now they are asking is we could accept the boards (qty = 1000)
this one time. My PCB spec does not allow silkscreen on any solderable
surface, so I could reject the boards, but my concern is that there may not
be enough time to have more boards fabricated in time for this build. I know
that the boards wouldn't be acceptable per IPC-A-610, but does anyone have
any experience with this situation and the best way to handle it?
Thank you,
Paul Black
Manufacturing Engineer
Kronos
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