[SI-LIST] Re: AW: Control Impedance testing
- From: "Lee Ritchey" <leeritchey@xxxxxxxxxxxxx>
- To: "Istvan Novak" <istvan.novak@xxxxxxx>
- Date: Mon, 14 Sep 2009 11:46:08 -0700
Istvan,
I agree with you on your points.. If we are lucky we won't find many PCBs
that need such rigorous testing. Diff signaling has gone a long way to
help on that.
> [Original Message]
> From: Istvan Novak <istvan.novak@xxxxxxx>
> To: Lee Ritchey <leeritchey@xxxxxxxxxxxxx>
> Cc: Steven Salkow <steven.salkow@xxxxxxxx>; Gert Havermann
<Gert.Havermann@xxxxxxxxxxx>; si-list@xxxxxxxxxxxxx <si-list@xxxxxxxxxxxxx>
> Date: 9/12/2009 7:53:15 PM
> Subject: [SI-LIST] Re: AW: Control Impedance testing
>
> Lee and All,
>
> If I interpret the question in the original post correctly, one aspect
> of the issue/concern here is whether we can take the test coupon result
> and apply it to the entire board. In other words: assuming that there
> is a test coupon inside our board with traces on all layers and for all
> different geometries/impedances, AND all of these traces are found to be
> within spec, does this guarantee that all of the other similar traces on
> the board are within spec? The answer is NO. This is why on demanding
> boards a periodical full-board scan is a good idea to find out the
> distribution of trace impedances over the various layers.
>
> Regards,
>
> Istvan Novak
> SUN Microsystems
>
>
> Lee Ritchey wrote:
> > It's much more reliable to build test traces right into the PCB. That
way,
> > impedance can be checked anytime. Very easy to do.
> >
> > Lee Ritchey
> >
> >
> >
> >> [Original Message]
> >> From: Salkow, Steven <steven.salkow@xxxxxxxx>
> >> To: Havermann, Gert <Gert.Havermann@xxxxxxxxxxx>; si-list@xxxxxxxxxxxxx
> >>
> > <si-list@xxxxxxxxxxxxx>
> >
> >> Date: 9/11/2009 5:39:54 PM
> >> Subject: [SI-LIST] Re: AW: Control Impedance testing
> >>
> >> Coupons are a practical way to audit Trace impedance. There should be
> >>
> > test coupons for every signal layer and every different type: i.e.
> > differential and single ended as required. Most fabricators can now
> > generate the test coupons too. If going this way, have them serialised
same
> > as board and note lot codes for tracking. See IPC 2221/2222 for more
info.
> > Your fabricator knows all about this - ask for a run down.
> >
> >> Steven Salkow
> >> Lockheed Martin
> >>
> >> -----Original Message-----
> >> From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]
> >>
> > On Behalf Of Havermann, Gert
> >
> >> Sent: Sunday, August 30, 2009 11:54 PM
> >> To: si-list@xxxxxxxxxxxxx
> >> Subject: [SI-LIST] AW: Control Impedance testing
> >>
> >> Dear Liao,
> >>
> >> there are some PCB maker out there with the capability and willingness
to
> >>
> > test all, or selected traces of your board. Of coarse you have to pay
for
> > this service, as well as you have to pay for very tight impedance
control.
> > For mass production this is not the way to go. You have to make shure
that
> > the design works within all production variations. For special test
cards,
> > thats another story. We found a PCB maker in Germany for such test
boards,
> > and they guaratee a 6% tolerance for prototype volumes and test most of
the
> > traces. Unfortunately, they can only test single ended, thus you have to
> > specify both impedances, and they will only guaratee the single ended to
> > come out right.
> >
> >> Let me know if you would like the contact data.
> >>
> >> BR
> >> Gert
> >>
> >>
> >>
--------------------------------------------------------------------------
> >> Absender ist HARTING Electronics GmbH & Co. KG; Sitz der Gesellschaft:
> >>
> > Espelkamp; Registergericht: Bad Oeynhausen; Register-Nr.: HRA 5596;
> > persönlich haftende Gesellschafterin: HARTING Electronics Management
GmbH;
> > Sitz der Komplementär-GmbH: Espelkamp; Registergericht der
> > Komplementär-GmbH: Bad Oeynhausen; Register-Nr. der Komplementär-GmbH:
HRB
> > 8808; Geschäftsführer: Torsten Ratzmann
> >
> >> -----Ursprüngliche Nachricht-----
> >>
> >> Von: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> >>
> > Im Auftrag von BO-LIAO
> >
> >> Gesendet: Sonntag, 30. August 2009 14:09
> >> An: si-list@xxxxxxxxxxxxx
> >> Betreff: [SI-LIST] Control Impedance testing
> >>
> >> Dear Sir,
> >>
> >> My PCB supplier doesn't test control impedance on actual board. They
said
> >>
> > control impedance is measured on test coupon.
> >
> >>
> >> Please advice if it is realistic and reliable to use the test coupon
> >>
> > measured impedance?
> >
> >>
> >> Is this an industry norm, or standard?
> >>
> >> Thank you.
> >>
> >> Best regards,
> >> Liao Bo
> >>
> >>
>
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