For regular VIAs, everywhere I look, here in MTL & TOR, the typical standard
is 10 mil with a 5 - 10 mil angular ring.
_____________
Brian Guralnick
----- Original Message -----
From: "Dennis Saputelli" <[EMAIL PROTECTED]>
To: "Protel EDA Forum" <[EMAIL PROTECTED]>
Sent: Monday, May 14, 2001 8:06 PM
Subject: Re: [PEDA] What size is a micro VIA
> micro vias (laser type) at least as explained to me DO NOT go all the
> way thru
>
> they only go from an outside layer to the next adjacent inner layer
> to me this seems to limit their usefulness because you then have to
> typically transition to a standard via which would have to be buried to
> be useful, esp. in the case of a dense bgas
>
> micro vias do allow hole in smd pad, they are too small to bother the
> paste much
>
> I think they were 5 mil dia and 2 mils deep, consult shop
>
> the smallest mech via I have found running around here is 18 mil via
> diameter, finished hole size should be spec'd as 0 to 10 mils, this
> allows vendor choice and means they don't need to guarantee that the via
> is not plugged or blocked by plating.
>
> these feature sizes are associated with 4/4 rules which are to be
> avoided if possible
> more buildable minimums would be 20 mil via, 5/5 rules
>
> we just did a job with a bunch of big dense 1mm BGAs and the trace
> density was such that we had to go to 4/4 to minimize layers to a
> thickness which would still insert into a PCI conn!
>
> protel could not route this board but spectra could (service was by Mike
> Reagan who did a very nice job)
>
> someday it would be nice to have variable trace/gap rules by area so
> that the rest of the board didn't also have to be 4/4
>
> Dennis Saputelli
>
> John Haddy wrote:
> >
> > I don't know whether there is a standard definition, but I
> > would regard it as a hole that couldn't be made reliably
> > using a standard drill-then-plate process.
> >
> > i.e. smaller than about 0.25mm finished hole size in a
> > 0.5mm diameter land.
> >
> > John Haddy
> >
> > > -----Original Message-----
> > > From: Brian Guralnick [mailto:[EMAIL PROTECTED]]
> > > Sent: Tuesday, 15 May 2001 8:05 AM
> > > To: Protel EDA Forum
> > > Subject: [PEDA] What size is a micro VIA
> > >
> > >
> > > Hi all,
> > >
> > > What diameter is considered a micro-Via?
> > >
> > > Thanks,
> > > _____________
> > > Brian Guralnick
> > >
> > >
> > >
> > >
>
> --
>
___________________________________________________________________________
> www.integratedcontrolsinc.com Integrated Controls, Inc.
> tel: 415-647-0480 2851 21st Street
> fax: 415-647-3003 San Francisco, CA 94110
>
>
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