[SI-LIST] Re: Causes of Phase Differences in stripline construction
- From: csullivan@xxxxxxxxxx
- To: Scott McMorrow <scott@xxxxxxxxxxxxx>, Craig Sullivan <csullivan@xxxxxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Fri, 9 Oct 2009 00:26:11 GMT
Hi Scott,
The material is Arlon 25N. Cores are 2113. Prepregs are 2112. Dk according
to the data sheet and data provided by Arlon is 3.38 +/- 0.06.
I will have to get the frequency when I get to work tomorrow.
Thanks,
Craig
> Craig
>
> It would help to know what material is being used, and the frequency
> specified for measurement of phase delta.
>
> Scott
>
> --
> Scott McMorrow
> Teraspeed Consulting Group LLC
> 121 North River Drive
> Narragansett, RI 02882
> (401) 284-1827 Business
> (401) 284-1840 Fax
>
> http://www.teraspeed.com
>
> Teraspeed® is the registered service mark of
> Teraspeed Consulting Group LLC
>
>
>
> Craig Sullivan wrote:
> > Hello,
> >
> >
> > I have a 2 part problem. Our customer has informed us they are seeing phase
> > errors in the assemblies we build for them. The requirement is all channels
> > need to have a phase delta of < 14.5 degrees. In other words, the max phase
> > - the min phase across 48 channels.
> >
> >
> >
> > Part 1 of the problem is a phase delta in excess of 30 degrees. We have
> > found the root cause of this problem to be PCB delamination.
> >
> >
> >
> > Part 2 of the problem is the phase delta around 15-18 degrees. This is
> > usually brought back into tolerance by changing an SMT capacitor.
> >
> >
> >
> > Finding the root cause of part 2 is proving to be rather challenging.
> > Originally the specification was < 8 degrees. When the customer started
> > seeing failures, they increased the specification to < 14.5. When they saw
> > even more failures in addition to the delam, they finally brought it to our
> > attention.
> >
> >
> >
> > In my opinion the stripline construction "should" be rather forgiving. It's
> > 1/2 oz, 19.4 mils wide surrounded by ~18 mil dielectrics on each side.
> > Though one of my concerns is each trace length is around 14.5 inches and is
> > serpentined. In addition, no two serpentine designs exhibit the exact same
> > pattern.
> >
> >
> >
> > Another concern I have is the channels are spread across 3 different layers
> > in the stackup (16 channels each on layers 2, 7, and 11). The PCB is 12
> > layers.
> >
> >
> >
> > Layers 2 and 11 have the same stackup:
> >
> > ==================== Ref
> >
> > 18 mil core
> >
> > -------------------- Signal
> >
> > 5.8 mil pp
> >
> > 6 mil core
> >
> > 5.8 mil pp
> >
> > ==================== Ref
> >
> >
> >
> > Layer 7 is slightly different:
> >
> > ==================== Ref
> >
> > 12 mil core
> >
> > 5.8 mil pp
> >
> > -------------------- Signal
> >
> > 18 mil core
> >
> > ==================== Ref
> >
> >
> >
> > Also to toss another variable in the mix. This board is completely round
> > with each channel beginning at the perimeter of the PCB and equidistant
from
> > the next channel. So with that said, I am aware of the trace orientation in
> > regard to weave/glass/resin now becomes a factor as well.
> >
> >
> >
> > So my question to the list is: What are some causes of an increased phase
> > spread? Also, any reference material recommendations are welcomed.
> >
> >
> >
> > Thank you,
> >
> > Craig Sullivan
> >
> > Manufacturing Engineer
> >
> > MPL Incorporated
> >
> > P: 607.266.0480
> >
> > F: 607.266.0482
> >
> > csullivan@xxxxxxxxxx
> >
> >
> >
> > Export Control:
> > This message is intended only for the addressee and may contain information
> > that is company confidential or privileged. Any technical data in this
> > message may be exported only in accordance with the U.S. International
> > Traffic in Arms Regulations (22 CFR Parts 120-130) or the Export
> > Administration Regulations (15 CFR Parts 730-774). Unauthorized use is
> > strictly prohibited and may be unlawful. If you are not the intended
> > recipient, or the person responsible for delivering to the intended
> > recipient, you should not read, copy, disclose or otherwise use this
> > message. If you have received this email in error, please delete it, and
> > advise the sender immediately.
> >
> >
> >
> >
> >
> > ------------------------------------------------------------------
> > To unsubscribe from si-list:
> > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
> >
> > or to administer your membership from a web page, go to:
> > //www.freelists.org/webpage/si-list
> >
> > For help:
> > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
> >
> >
> > List technical documents are available at:
> > http://www.si-list.net
> >
> > List archives are viewable at:
> > //www.freelists.org/archives/si-list
> > or at our remote archives:
> > http://groups.yahoo.com/group/si-list/messages
> > Old (prior to June 6, 2001) list archives are viewable at:
> > http://www.qsl.net/wb6tpu
> >
> >
> >
> >
>
---------------------------------------------
This message was sent using Endymion MailMan.
http://www.endymion.com/products/mailman/
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
