Mike,
I also agree. How the via is formed is not that important. In fact
there are applications were a combination of mechanical and Laser are
being used. On the aspect ratio side we have had a number of discussions
with customers and labs on how to accurately measure the aspect ratio.
Is it the aperture of the hole at the surface, at the target land or
some combination? As these holes are very small and it is difficult to
grind to the exact center of the hole it makes it very hard to measure;
especially at the bottom were the hole has some slant or curve to it. As
you know what size laser aperture or drill you are using it makes it
easy and straight forward for the board shop to use the top surface
diameter.
Wendi
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Mike Hill
Sent: Monday, April 27, 2009 11:49 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] controlled depth, tapered drill 'micro' vias
Fritz,
I agree. the method to make the hole is not important, since the
reliability
of such holes is mainly dependent on copper thickness and the amount of
dielectric that can expand. I would hope us folks in the 6012 committee
could agree that a microvia is something like "any hole 10 mils or less
with
an aspect ratio under 1.5 with the copper requirements presently in
6012".
Mike Hill
Colonial Circuits
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]]On Behalf Of Francis
Byle
Sent: Monday, April 27, 2009 10:36 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] controlled depth, tapered drill 'micro' vias
I am in complete agreement with Chris. Whether a via is ablated,
drilled, or nibbled by microorganisms, the quality and performance
standards should be the same. This needs to be addressed in 6012/6013,
not just in T50.
Regards,
Fritz
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Chris
Mahanna
Sent: Monday, April 27, 2009 09:29
To: [log in to unmask]
Subject: Re: [IPC-600-6012] controlled depth, tapered drill 'micro' vias
Hey John,
Yes. Thanks for posting the proposed 'current' definition. IMO the
mechanical drill exclusion will cause us more problems than it's worth,
in the long run. Keep in mind for instance- sometimes we can't
determine for sure whether it is a taper drill or ablation.
The only benefit of using the mechanical drill exclusion is that we
don't have to define a new upper limit diameter. The irony is that my
customers already routinely use the HDI design standard(s) to circumvent
the (what appears to them as an arbitrary) 6 mil limit. But, the design
standard didn't know that 6012 was going to define a microvia and allow
it to have 1/2 the plating/wrap. So who's driving :) ?!
With 6016 inactive, I suppose it is left to 6012/6013/Via Reliability
Committee/T-50 to reconcile. Definitely beyond the scope of just T-50.
We can put it on the list for next time.
Chris
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of John Perry
Sent: Friday, April 24, 2009 3:25 PM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] controlled depth, tapered drill 'micro' vias
Hi Chris,
What do you have for the current definition? Does it match the
following: "Microvias are defined as less than or equal to 1:1 aspect
ratio (excludes mechanical drill) or mechanically drilled < 0.15 mm
[0.006 in]."? This is what I have in the new IPC-6012C tables for
minimum plating in the microvia as result of the Las Vegas APEX-Expo
meetings.
I could ask Mike Green and Vicka White if we could steal the next 2-30
Terms and Definitions conference call on April 28th at 11AM Eastern if
they agree this is something we should work to finalize.
Best Regards,
John Perry
Technical Project Manager
IPC - Association Connecting Electronics Industries(r) 3000 Lakeside
Drive # 309S Bannockburn, IL 60015-1249 USA
+1 847-597-2818 (tel)
+1 847-615-7105 (fax)
+1 847-615-7100 (Main)
[log in to unmask]
www.ipc.org
-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Chris
Mahanna
Sent: Friday, April 24, 2009 9:12 AM
To: [log in to unmask]
Subject: [IPC-600-6012] controlled depth, tapered drill 'micro' vias
Hello everyone,
I've got some Friday fun.
Some of you will recall that I was rather irritated by the outcome of
the "redefining microvia" vote.
Time is running short for me to make a final plea to the group before
6012C release. Maybe time is up? (sorry John) Assuming that some of
these will eventually be classified as microvias, it seems
counterproductive to run with our new definition in 6012 and T-50.
I believe that we need to decouple the formation technique from the
aspect ratio and micro via classification.
The argument against my definition was that there is no peer reviewed
data or publications about the reliability of capture side diameters
greater than 6 mils.
The attached images are cherry-picked to spur conversation. BTW- there
are no dielectric violations from these samples.
Thanks,
Chris
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