[SI-LIST] Re: NELCO N-13ep HiTg > 170C
- From: Richard Jungert <r_jungert@xxxxxxxxxxx>
- To: steve weir <weirsi@xxxxxxxxxx>, <wftinghi@xxxxxxxxxxxxxx>, <bdempsey85@xxxxxxxxx>, <costel_t@xxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Sat, 6 Sep 2008 18:28:00 -0700
Steve.
Thats all basic VSWR stuff where you combine the impedance mismatch on the
source with the mismatch on the end to calculate the total signal loss in the
system.
We did not build a 100 ohm differential system, it was a 50 ohm system. Simply
put our customer wanted accuracy, so we took the exta time to build it with
tighter tolerances. We did pretty much what they wanted and they paid for it.
Sometimes customers are picky about certain things and one just has no choice
but to give what they want.
I agree with you totally when it comes to 100 ohm differential. But 50 Ohm
stuff requires more precision for fast TDR testing apps. 100 ohm differential
stuff is almost a no brainer, its real solid, low loss, noise cancelling
technology. Throw it together and it works kind of stuff. There is still alot
of 50 ohm equipment around these days.
By the way if anyone wants a good wideband, multi-channel 100 ohm diff cable
shoot me an email and I will give info.
I used to test Digital Microwave Radios for ISI in baseband circuits, VSWR on
the RF side and EB/NO in the digital reciever.
Richard Jungert
> Date: Sat, 6 Sep 2008 17:54:31 -0700
> From: weirsi@xxxxxxxxxx
> To: r_jungert@xxxxxxxxxxx
> CC: wftinghi@xxxxxxxxxxxxxx; bdempsey85@xxxxxxxxx; costel_t@xxxxxxxxx;
> si-list@xxxxxxxxxxxxx
> Subject: Re: [SI-LIST] Re: NELCO N-13ep HiTg > 170C
>
> Richard, VSWR causes ISI ( as does frequency dependent loss ): Signal
> energy reflects first off the receiver back up the line to the
> transmitter where it distorts currently transmitted data. Since the
> distortion depends on prior data patterns it manifest as ISI. A simple
> chart for line impedances:
>
> Reflected amplitude: ( Zline - Zload ) / ( Zline + Zload )
> One term pessimistically assumes 0 Ohm driver
> Z Line One term Two term
> 80% -11.1% +1.2%
> 85% -8.1% +0.7%
> 90% -5.3% +0.2%
> 95% -2.6% +0.1%
> 98% -1.0% +0.0%
> 102% +1.0% +0.0%
> 105% +2.4% +0.1%
> 110% +5.8% +0.2%
> 115% +7.0% +0.5%
> 120% +9.1% +0.8%
>
> In older signaling topologies with just one termination, tightening up
> tolerances buys ISI margin. In double terminated topologies there is
> little to gain ISI wise with matches better than 15%. This has some
> nice implications:
>
> 1. We can get away with skinnier traces and thinner dielectrics without
> worrying too much about etch tolerance for Z control, and
> 2. We also don't need to be concerned about placing etch across prepreg
> from return planes for Z control. That makes putting the top power
> cavity on layers 2/3, and the bottom one on N-1/N-2 where they perform
> best and reduce the number of bypass caps needed a no-brainer. With
> older singly-terminated signaling schemes there was an argument for
> putting signal on one side of a core and plane on the other for low-cost
> Z control. Typically that put Gnd on layer 2, signals on layers 3 and
> 4, and the first power cavity down on layers 5/6, which really hurts Z
> axis inductance for both bypass caps and the ICs. It is also
> incompatible with thin core dielectrics for power delivery.
>
> If you are making a piece of measurement equipment then depending on
> what you want to see the extra precision may be justified.
>
> Best Regards,
>
>
>
> Steve.
>
> Richard Jungert wrote:
> > Steve.
> >
> > Its not about ISI, ( intersymbol interference) as I recall. Its all
> > about test equipment, accuracy and precision results in smaller
> > reflections and better VSWR within the bandwidth of interest.. Good
> > quality test equipment is all about precision, but precision costs
> > money as we all know. We were making a tester box that connected to
> > multi channel wide bandwidth cable ( single ended 50 ohms ) and tested
> > with 35ps risetime signaling from Tek equipment. It worked but was
> > expensive to make.
> >
> > Richard Jungert
> >
> >
> >
> >
> > > Date: Sat, 6 Sep 2008 14:44:39 -0700
> > > From: weirsi@xxxxxxxxxx
> > > To: r_jungert@xxxxxxxxxxx
> > > CC: wftinghi@xxxxxxxxxxxxxx; bdempsey85@xxxxxxxxx;
> > costel_t@xxxxxxxxx; si-list@xxxxxxxxxxxxx
> > > Subject: Re: [SI-LIST] Re: NELCO N-13ep HiTg > 170C
> > >
> > > We're not in Kansas anymore. ( Well Eric is but that's only because he
> > > likes watching cows spin in tornadoes. ) The days of TTL/CMOS signaling
> > > with one end terminated at speed are long gone. So, why the drive for
> > > such tight Z control as +/-5%? The difference in ISI energy at the
> > > receiver between a +/-10% match and a +/-5% match for both ends
> > > terminated signaling standards is less than 1%. Why throw any time or
> > > money at such a small improvement?
> > >
> > > Steve
> > >
> > > Richard Jungert wrote:
> > > > Steve.
> > > >
> > > > Yes, +/- 5% is higher, how much depends on your fab house. I would
> > have to shop around if we needed lower cost. At the time 3 years ago I
> > was building test equipment and yes the board was expensive. The
> > application we were working on demanded tight impedance control.
> > > >
> > > >
> > > > BTW.
> > > >
> > > > This guy..
> > > > Vince BeusanMEI Inc(949)460-9500www.mei4pcbs.comTells me in a
> > recent email that his fab shop can do +/-5% all day long no problem
> > but I have not worked with them in the past. Maybe these guys have an
> > updated fab process set up where they can do tighter tolerance at
> > lower cost. Only way to find out is to try it.
> > > > Richard
> > > >
> > > >
> > > >
> > > >
> > > >> From: wftinghi@xxxxxxxxxxxxxx
> > > >> To: r_jungert@xxxxxxxxxxx; bdempsey85@xxxxxxxxx;
> > costel_t@xxxxxxxxx; si-list@xxxxxxxxxxxxx
> > > >> Subject: RE: [SI-LIST] Re: NELCO N-13ep HiTg > 170C
> > > >> Date: Sat, 6 Sep 2008 10:22:01 +0800
> > > >>
> > > >> Richard,
> > > >>
> > > >> So how about the cost? I feel +/-5% tolerance impedance control will
> > > >> increase the PCB cost a lot.
> > > >> The most local FAB houses I worked with will increase the cost if
> > we are
> > > >> trying to specify tolerance less than 10% due to their worse
> > yield rate.
> > > >> Specifying 5% tolerance can easily double the cost according to their
> > > >> feedbacks.
> > > >>
> > > >> Steve
> > > >>
> > > >> -----Original Message-----
> > > >> From: si-list-bounce@xxxxxxxxxxxxx
> > [mailto:si-list-bounce@xxxxxxxxxxxxx] On
> > > >> Behalf Of Richard Jungert
> > > >> Sent: Saturday, September 06, 2008 5:12 AM
> > > >> To: Bill Dempsey; costel_t@xxxxxxxxx; si-list@xxxxxxxxxxxxx
> > > >> Subject: [SI-LIST] Re: NELCO N-13ep HiTg > 170C
> > > >>
> > > >> I promote Data Circuits Systems/Merix because they can spec 50
> > ohms +/- 5%
> > > >> tolerance which in my experience is rare in the high speed pcb
> > fab business.
> > > >> Or at least it was 3 years ago.. Tektronix also uses this material in
> > > >> building fast TDR test equipment last I heard.
> > > >>
> > > >> Richard
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>> From: bdempsey85@xxxxxxxxx
> > > >>> To: r_jungert@xxxxxxxxxxx; costel_t@xxxxxxxxx; si-list@xxxxxxxxxxxxx
> > > >>> Subject: RE: [SI-LIST] Re: NELCO N-13ep HiTg > 170C
> > > >>> Date: Fri, 5 Sep 2008 16:02:59 -0500
> > > >>>
> > > >>> 13EP is available as 13EP-SI as well and is used for higher temp
> > > >>>
> > > >> processing
> > > >>
> > > >>> used in lead-free assembly.
> > > >>> *Most* customers I deal with are moving over to EP and EP-SI for
> > RoHS
> > > >>> products. Something to consider.
> > > >>>
> > > >>> -----Original Message-----
> > > >>> From: si-list-bounce@xxxxxxxxxxxxx
> > [mailto:si-list-bounce@xxxxxxxxxxxxx]
> > > >>>
> > > >> On
> > > >>
> > > >>> Behalf Of Richard Jungert
> > > >>> Sent: Friday, September 05, 2008 3:58 PM
> > > >>> To: costel; si-list@xxxxxxxxxxxxx
> > > >>> Subject: [SI-LIST] Re: NELCO N-13ep HiTg > 170C
> > > >>>
> > > >>> Costel.
> > > >>>
> > > >>> I would talk to the engineers at Data Circuits in San Jose about
> > this
> > > >>> material. Merix recently bought them out but in the old days it
> > was Data
> > > >>> Circuits Systems Inc who built equipment with this type of material.
> > > >>>
> > > >>> Have you considered Nelco N4000-13SI ? This is also a very high
> > > >>>
> > > >> performance
> > > >>
> > > >>> material and in my recent designs/projects have found this
> > material works
> > > >>> clear up to 15Ghz bandwidth.
> > > >>>
> > > >>> I recommend calling the FAB house your working with. These folks
> > have that
> > > >>> info readily available.
> > > >>>
> > > >>> Richard Jungert
> > > >>>
> > > >>>
> > > >>>
> > > >>>
> > > >>>> Date: Fri, 5 Sep 2008 03:31:05 -0700
> > > >>>> From: costel_t@xxxxxxxxx
> > > >>>> Subject: [SI-LIST] NELCO N-13ep HiTg > 170C
> > > >>>> To: si-list@xxxxxxxxxxxxx
> > > >>>>
> > > >>>> Can anybody tell me the prepreg thicknesses for NELCO N4000-13EP
> > > >>>> much apreciated
> > > >>>>
> > > >>>>
> > > >>>>
> > > >>>>
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