Hi Bill
Please could you send a link to your paper since SI-List doesn't pass
through attachments?
Regards
Jonathan
On 16 Oct 2017 19:00, "Bill Birch" <bill.birch@xxxxxxxxxxx> wrote:
Hi Alex, Aubrey,
The recently completed HDPUG project comparing "stacked-on" HDI to
"offset-to" HDI did not include staggered structures because the
reliability of the staggered features is not considered a reliability
concern. In the majority of cases the electrical designer does not want to
resort to staggered structures because of signal integrity issues and the
obvious increased density available with stacked configuration. The
attached paper describes the results of testing the two stacked options,
the reliability impact is apparent. We are hoping the industry standards
organizations take these results seriously and introduce "warnings" to
designer that elect to place their HDI feature directly onto the
sub-laminated structures.
I hope you find the paper interesting.
Best regards,
Bill.
-----Original Message-----
From: Aubrey Sparkman [mailto:asparky@xxxxxxxxxxxxxxxxxxxxxxxx]
Sent: Monday, October 16, 2017 9:54 AM
To: alexander.ippich@xxxxxxxxxxxxxxx
Cc: w.maichen@xxxxxxx; Bill Birch <bill.birch@xxxxxxxxxxx>;
dmarc-noreply@xxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: Re: [SI-LIST] Re: Stacked microvia on high speed diff layer
transitions
Alex,
Yes, I'm pretty sure putting stacked microvias on top of a through-hole
via is a no-no from a reliability perspective.
So the real question is whether there is public reliability data for
staggered micro vias vs stacked vias that aren't on top of a through-hole
via.
Thanks,
Aubrey
Sent from my iPhone
On Oct 16, 2017, at 6:29 AM, Alexander Ippich <alexander.ippich@xxxxxxxxxxxxxxx> wrote:
Aubrey,
there was a HDPUG project looking into comparing a stack of microvias
put right on top of a buried via against a stack of microvias put with
an offset on the buried vias. In both cases, all the microvias were
put directly on top of each other (stacked). Only difference was
having the buried vias underneath also being at the same location or
shifted (using a dogbone).
That project was "Reliability of Multi-Lamination Structures in
Pb-Free Assembly" and testing was performed by PWB (actually Bill
Birch reported on this at the EIPC Winter Conference in 2016).
Comparing these two options in fact showed better reliability with the
offset. But please keep in mind, that this was not about staggering
the microvias but just for the one transition 'buried via to micro via'.
Not sure, if Bill has also comparative data between stacked and
staggered microvias and if he would be willing to speak to this here.
Bill - just in case you are - I guess the group would be very happy to
hear from you about this.
Best regards,
alex
----------------------------------------------------------------------
----
--------------------------------------------------------------
Alexander Ippich
Technical Director, Signal Integrity & Advanced Technology OEM
Marketing Europe
e-mail: alexander.ippich@xxxxxxxxxxxxxxx
web: www.isola-group.com
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