Hi Nicholas,
The plating pits I mentioned could be caused by several different factors.
More than likely it would be air saturation in the plating baths. But, no
matter what the cause is, they could appear similar to what you described.
Picture an air bubble attaching (lodging) itself on a circuit while in the
copper plating tank (trapped between the resist as it defines the trace).The
bubble inhibits plating allowing little or no copper to deposit (depending
on how soon in the cycle it finds the trace). However, it does take tin or
tin/lead plating after being removed from the copper tank and rinsed. So,
the tin protects the copper trace from complete etch-through yet there has
been no copper plating to build the trace up.
That sort of defect would normally appear circular, like a bubble. If your
defect is more flattened looking or the edges are more "undefined" than
circular, odds are you have resin spots on the foil coming from lamination.
If you need any further help you can reach me off-line whenever you want.
Good luck
Mark Mazzoli
Eng. Mgr.
Circuit Technologies, Inc.
3622 Clearview Pkwy.
Atlanta, GA 30340
770-458-1700
[log in to unmask]
----- Original Message -----
From: Nicholas LAI <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, August 30, 1999 9:25 PM
Subject: Re: [TN] Nick circuit can't detect.. Problem
> Can u illustrate the second point..... I cannot catch the meanings.
> Thanks for ur help.
>
> Best Regard,
> 8/31/99
>
>
>
>
> Mark Mazzoli <[log in to unmask]> on 99/08/30 07:06:09 PM
>
> Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please
respond to
> Mark Mazzoli <[log in to unmask]>
>
> To: [log in to unmask]
> cc: (bcc: Nicholas LAI/CS/Topsearch)
>
> Subject: Re: [TN] Nick circuit can't detect.. Problem
>
>
>
> Hi Nicholas,
> Two ideas as to the "dish down" problem. One, they could be resin spots
> left on after lamination. They will resist subsequent plating and etching
> yet leave the base copper intact after etching. Or, two, plating pits.
> They can (and usually do) span the width of the trace (especially if
they're
> due to air supersaturation in the copper baths). I was unable to open
your
> attached file so these suggestions are based on your description only.
>
> Good luck
>
> Mark Mazzoli
> Eng. Mgr.
> Circuit Technologies, Inc.
> 3622 Clearview Pkwy.
> Atlanta, GA 30340
> 770-458-1700
> [log in to unmask]
> ----- Original Message -----
> From: Nicholas LAI <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Saturday, August 28, 1999 12:32 AM
> Subject: [TN] Nick circuit can't detect.. Problem
>
>
> >
> >
> > There is some problems I cannot be solve... Hope all of your can help
> me...
> >
> > (1)We found that there is many board can be escape from E-test...
> > After micro-section analysis, we found that there is still base copper
on
> trace
> > open location.
> > We can said that the problem is dish down ... There is still connected
but
> the
> > resistance is greater than normal one...
> >
> > What is the cause of this defect?
> > Is there any reliable method to detech it?
> > Is there any apparatus can detech the nick circuit problem expect AOI.?
> >
> > (Embedded image moved to file: pic22705.pcx)
> >
> > Best Regard,
> > nicholas lai
> >
> >
> >
>
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