Excellent pictures Steve!!!   In my previous life we used Metro circuirts
and there Conductive Epoxy fill and that seemed to work real well.   Before
that we had all kinds of problems making people believe that via's in pads
are bad/  You know that those RF guys like to have every circuit grounded
as many times and often as they can.   Like you said they fill up the pads
with via's and when you tell them it will not work they say "come on you,
you can't be serious".   And when you spend all that time reworking those
spots because Quality saids "Insufficient solder" the engineer says "You
must not have printed your paste right"  And it is then that you pick up
that Ball peen Hammer and chase him around the building.



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                    04/03/02 04:45
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Ahhh vias in pads...what timing. In fact built a board last week that I had
no idea
that they put vias in the pads until the bare fab showed up. Soon as I seen
it I was
screaming like a banshee!!

Them: What's wrong Steve? Why are you so wound-up?

Me: Because there's vias in the pads!!

Them: Is that really a problem? Won't the solder just fill them up?

Me: Yes it will...and take all the solder away from the fillet to do it...

Them: Oh it can't be that bad, the via is so small...

Me: Okay, trust me on this...you'll see.

Go to: http://www.stevezeva.homestead.com   and tell me I was right.

Luckily, this is just a pre-production build of 10 boards...I think there
is going to be a redesign after this...hehehe

-Steve Gregory-


 This problem is never ending. I'm working now on the ugliest R/F board
 imagineable. It too has all your problems. However, I have a forward
 thinking engineer who understands the issues involved as you state them.
 We
 are redesigning and he's recalculating to eliminate those issues. So, it
 can
 be done. No, unless you redesign, you have a lost cause notwighstanding
 rework adn subsequentg chip cracking due to thermal issues related trying
 to
 solder the little mutha's.

 You can add vias in pads only as micro types or those having been plugged
 and plated over. Still a redesign exists.

 On the same note, can someone recommend a good R/F and other electrical
 performance tool that is relatively easy to use? Hell of a question I
 know,
 but consider the source.

 MoonMan

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