i assume you meant '99SE' ?

the autorouter for it's time (which was not new even at that time)
actually wasn't too bad, but it certainly was not made to do BGAs

it did do a decent job at lined up rows of random wired DIPS  :)

i wouldn't get my hopes up about autorouting that thing

to do a solder mask opening smaller than the pad use a negative expansion

my brain is wired in mils so...
for a 40 mil pad with a 30 mil opening use
solder mask expansion of -5 mils

what is driving the 'solder mask defined' ?
i have read both pros and cons about that but everyone i know does not do it

.125mm is 4.9 mils
5 mil trace/space is almost ordinary these days

for BGAs depending on the pitch we sometimes need to go to 4mil trace 
4mil space AKA 4/4


Dennis Saputelli


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Stephen R Phillips wrote:
> I've made LFBGA PCB parts in protel 98 SE and I'm rather concerned or
> is that befuddled? hmmmm
> in any case what I have done I've been experimenting with a 4 layer
> board and the (miserable) autorouter that came with it.
> I've made the layer type of the pads multilayer so that each layer of
> the board can connect to a pin.
> Right so what's the problem?
> 
> Well there are several options for the solder mask and yet I can't see
> where to specify them in the package information.  IE in the LFBGA144
> package I should be able to specify a solder mask defined pad with a
> solder mask hole of 0.38mm and a pad size of 0.48 mm.  I also should be
> able to specify a non solder mask defined pad with solder mask hole of
> 0.50mm and a solder pad of 0.35mm.  
> 
> Next comes .. what trace width should I use. Currently (rightly or
> wrongly) I'm attempting to use 0.125mm trace widths for connecting to
> the pads.  Too large? Too small? I have been setting that as the
> smallest but I'm thinking that is not as wise as I had thought before. 
> 
> Is it possible to associate a set of rules WITH a package? IE LFBGA
> package automatically defines the rules for the nets that connect too
> it.  Hints pointers appreciated.  I would like to have the design rules
> twisted.. err pushed toward sane directions before the autorouter goes
> insane err begins it's job.
> 
> In summary, how do I define the solder masked used with a specific
> package, what is a proper trace width too use with 0.8 mm pitch BGA
> packages, and is it possible to semi automate setting the design rules
> based on package used with a net?
> 
> Stephen
> 
> Stephen R. Phillips was here
> Please be advised what was said may be absolutely wrong, and hereby this 
> disclaimer follows.  I reserve the right to be wrong and admit it in front of 
> the entire world.
> 
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