What are the odds of solder mask defined pads ?
I sometimes hear people say it's better to use solder mask defined pads
because they allow you to use
larger drill diameters ( ans thus a lower aspect ratio etc...).
Today's reflow technology should be able to cope with a certain amount of
heat leakage from the
BGA solderlands towards internal planes of full copper along the via, that
is so closely attached to the solderland of
a soldermask define pad.

Thanks in advance to anyone who can help me to clear out this item of
debate.

Cor Coolen
LAYERS/The House of PCB Design
De Vunt 13  B-3220 HOLSBEEK - Belgium
tel: +32-16-441414
fax: +32-16-441416
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data transfer: [log in to unmask]
http://www.layers.be

----- Original Message -----
From: Ed Valentine <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, September 22, 2000 10:22 PM
Subject: Re: [DC] uBGA


> Tony -
>
> As with other surface mount components, I strongly recommend that you
don't
> use solder mask defined pads if at all possible.
>
> Ed Valentine
> Electronics Manufacturing Solutions
> 8612 Mourning Dove Road, Raleigh, NC 27615
> Phone: (919) 270-5145, Fax: (919) 847-9971
> Email: [log in to unmask]
> Website: http://www.ems-consulting.com
>
> ----- Original Message -----
> From: "Huffman, Tony" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Friday, September 22, 2000 11:43 AM
> Subject: [DC] uBGA
>
>
> > Greetings,
> >         I am gearing up for my first BGA design and it is a .8mm pitch
> uBGA.
> > Any help for me to find literature on-line that will help me gear up for
> > this would be appreciated. There are things like Solder Mask Defined
pads
> > vs. Non Solder Mask Defined pads that I am not sure on which way to go.
> > Thanks in advance.
> >
> > > Tony G. Huffman
> > > PC Board Layout Specialist
> > > Hunter Engineering Company
> > > 11250 Hunter Drive
> > > Bridgeton, Mo. 63044
> > > [log in to unmask]
> > > (314)731-0000 ext.330
> > > (314)731-9932 FAX
> > > http://www.hunter.com
> > >
> > >