[SI-LIST] Re: Impedance Controlled Board Production Vs Normal Board Production

  • From: "Jayasuryan KG" <suryan_tvm@xxxxxxxxxxx>
  • To: <si-list@xxxxxxxxxxxxx>
  • Date: Mon, 9 Jan 2012 23:13:03 +0530

Dear All,

Thanks for your valuable reply! Its really help me to solve some confusions.
Once again, thanks for your time and consideration!

Best Regards,
Jayasuryan

-----Original Message----- 
From: Lee Ritchey
Sent: Saturday, January 07, 2012 4:51 AM
To: Scott McMorrow ; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Impedance Controlled Board Production Vs Normal Board 
Production

Good reply!

Lee


-----Original Message-----
>From: Scott McMorrow <scott@xxxxxxxxxxxxx>
>Sent: Jan 6, 2012 6:45 AM
>To: si-list@xxxxxxxxxxxxx
>Subject: [SI-LIST] Re: Impedance Controlled Board Production Vs Normal 
>Board Production
>
>Did I just see an eye diagram in the sky?  To the simulation cave ....
>
>Scott McMorrow
>Grand Poobah
>  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
>
>
>On 1/6/2012 3:44 AM, Tom Dagostino wrote:
>> This is a job for Simulation Man.
>>
>> One needs to look at the spec for any particular application and 
>> determine
>> through analysis what the tolerance can/should be.  There is no rule of
>> thumb that works.
>>
>> Tom Dagostino
>>
>> Teraspeed Labs
>> 9999 SW Wilshire St.
>> Suite 102
>> Portland, OR 97225
>> USA
>>
>> 971-279-5325  Office
>> 971-279-5326   FAX
>> 503-430-1065  Cell
>>
>> tom@xxxxxxxxxxxxx
>> www.teraspeed.com
>>
>> Teraspeed Consulting Group LLC
>> 121 North River Drive
>> Narragansett, RI 02882
>> 401-284-1827
>>
>>
>> -----Original Message-----
>> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] 
>> On
>> Behalf Of Rajan Hansa
>> Sent: Thursday, January 05, 2012 11:46 PM
>> To: si-list@xxxxxxxxxxxxx
>> Cc: David Siadat (dsiadat)
>> Subject: [SI-LIST] Re: Impedance Controlled Board Production Vs Normal 
>> Board
>> Production
>>
>> guys don't you think that if impedance variation is under 10 % then we
>> shouldn't worry much about it.
>> My analogy is that for 10 % impedance variation return loss is more than
>> -20 db and effect of this return loss is less than 0.5 db on insertion 
>> loss
>> which is quite acceptable when we compare it with losses due to 
>> attenuation
>> on  insertion loss.
>>
>> Correct me if i am wrong or am I missing something ???
>>
>>
>> On Fri, Jan 6, 2012 at 3:51 AM, David Siadat (dsiadat)
>> <dsiadat@xxxxxxxxx>wrote:
>>
>>> I agree with Aubrey's statement.
>>> If you do not specify Impedance Control design (possibly for each
>>> layer), then traces on the layer with not enough copper material will
>>> have more than +/-10% impedance variations even if you specified its
>>> characteristic impedance in your request!
>>>
>>> -David
>>>
>>> -----Original Message-----
>>> From: si-list-bounce@xxxxxxxxxxxxx
>>> [mailto:si-list-bounce@xxxxxxxxxxxxx]
>>>   On Behalf Of Aubrey K Sparkman
>>> Sent: Thursday, January 05, 2012 11:49 AM
>>> To: Michael Greim
>>> Cc: Ken Cantrell; Mikhail Matusov; si-list@xxxxxxxxxxxxx
>>> Subject: [SI-LIST] Re: Impedance Controlled Board Production Vs Normal
>>> Board Production
>>>
>>> Michael,
>>>
>>> A fab house only has to meet the specifications in the contract.  I
>>> would say the company got what they specified.
>>>
>>> My point was that an impedance only specification is often inadequate.
>>>
>>>
>>> Aubrey
>>>
>>> On 1/5/12 1:16 PM, "Michael Greim"<mgreim001@xxxxxxxxx>  wrote:
>>>
>>>> There needs to be an interlock between the fab house and design team.
>>>> If different construction methods are employed and they aren't
>>>> checked then offending engineer is really getting what they deserve.
>>>> Check twice, or more, and cut once is a lesson often learned quite
>>>> painfully.
>>>> -Michael
>>>>
>>>> On Thu, Jan 5, 2012 at 10:27 AM, Aubrey K Sparkman<
>>>> asparky@xxxxxxxxxxxxxxxxxxxxxxxx>  wrote:
>>>>
>>>>> Ken,
>>>>>
>>>>> What you say is true.   What hasn't been mentioned is the risk behind
>>>>> specifying only the impedance.
>>>>>
>>>>> Mikhail makes a good point about specifying the board stackup
>>>>> CONSTRUCTION.  I have seen failures when impedance only was
>>> specified.
>>>>> The design went out as a dual stripline with 4 mil cores between
>>>>> the  signals and their respective reference planes and a 12 mil
>>>>> prepreg between  the two signal layers.  The pcb house was given
>>>>> permission to use 5
>>> mil
>>>>> cores since they didn't have 4 mil cores in stock.  For the 2nd
>>> build,
>>>>> the
>>>>> pcb house outsourced the design to another house which used 8 mil
>>> cores.
>>>>> Trace widths and prepreg thickness were adjusted appropriately so
>>> that
>>>>> both board thickness and impedance specifications were met.
>>>>>
>>>>> Any guesses about the performance of the boards in the 2nd build?
>>>>>
>>>>> Aubrey Sparkman
>>>>> SparkRight Solutions
>>>>>
>>>>> On 1/5/12 10:36 AM, "Ken Cantrell"<Ken.Cantrell@xxxxxxxxxxxxxxxx>
>>>>> wrote:
>>>>>
>>>>>> Mikhail,
>>>>>> I'm not disputing anything that you said, just pointing out that:
>>>>>> "If I, as a designer, know the process and materials used by the
>>>>>> particular manufacturer well enough" is a big If.  That's a mature
>>>>>> designer talking.  Not something a relative beginner would know or
>>>>>> even be able to accomplish.
>>>>>>
>>>>>> 2cents
>>>>>> Ken
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: si-list-bounce@xxxxxxxxxxxxx
>>>>>> [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Mikhail Matusov
>>>>>> Sent: Thursday, January 05, 2012 9:05 AM
>>>>>> To: si-list@xxxxxxxxxxxxx
>>>>>> Subject: [SI-LIST] Re: Impedance Controlled Board Production Vs
>>> Normal
>>>>>> Board Production
>>>>>>
>>>>>>
>>>>>> I don't think those who responded understood the question correctly.
>>> I
>>>>>> think
>>>>>> the OP was asking whether some degree of impedance control can be
>>>>> achieved
>>>>>> by precisely specifying the board's stackup, width of the traces,
>>> and
>>>>>> process tolerances without explicitly asking the manufacturer to
>>>>> control
>>>>>> impedance. For some applications it just boils down to the cost.
>>>>>> If
>>> I,
>>>>> as
>>>>>> a
>>>>>> designer, know the process and materials used by the particular
>>>>>> manufacturer well enough I should be able to specify the board in
>>>>>> such a way that
>>>>> the
>>>>>> impedance will end up in  the right ballpark. In fact, I use this
>>>>> method
>>>>>> for
>>>>>> non-critical designs.
>>>>>>
>>>>>> =======================
>>>>>> Mikhail Matusov
>>>>>> Senior Hardware Design Engineer
>>>>>> Square Peg Communications
>>>>>> Tel.: +1 (613) 271-0044 ext.231
>>>>>> Fax: +1 (613) 271-3007
>>>>>> http://www.squarepeg.ca
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> ----- Original Message -----
>>>>>> From: "Loyer, Jeff"<jeff.loyer@xxxxxxxxx>
>>>>>> To:<si-list@xxxxxxxxxxxxx>
>>>>>> Sent: Thursday, January 05, 2012 10:22 AM
>>>>>> Subject: [SI-LIST] Re: Impedance Controlled Board Production Vs
>>> Normal
>>>>>> Board
>>>>>> Production
>>>>>>
>>>>>>
>>>>>>> Perhaps I'm the only one who is finding it ironic that, on a
>>> "Signal
>>>>>>> Integrity" reflector list, "Impedance Controlled" isn't
>>>>>>> considered "Normal".  I haven't had the luxury of not specifying
>>>>>>> impedance
>>>>> control
>>>>>>> since a small 33MHz PCI card design, many years ago.
>>>>>>>
>>>>>>> I'm afraid Jayasuryan that you won't find the answer you're
>>> looking
>>>>> for
>>>>>>> on
>>>>>>> an e-mail thread, or it is going to be a long, drawn out,
>>>>>>> painful affair.
>>>>>>> You have a lot of work to do to understand what impedance
>>>>>>> control
>>> is
>>>>> and
>>>>>>> how it relates to signal integrity.  I would recommend starting
>>> with
>>>>> the
>>>>>>> books that have been listed many times on this list.  You can
>>>>>>> also search  the archives for "impedance control" to find
>>>>>>> discussions about
>>>>> different
>>>>>>> opinions on how much is enough.
>>>>>>>
>>>>>>> Good luck in the new year,
>>>>>>> Jeff Loyer
>>>>>>>
>>>>>>> -----Original Message-----
>>>>>>> From: si-list-bounce@xxxxxxxxxxxxx
>>>>> [mailto:si-list-bounce@xxxxxxxxxxxxx
>>>>> ]
>>>>>>> On Behalf Of steve weir
>>>>>>> Sent: Monday, January 02, 2012 6:23 AM
>>>>>>> To: si-list@xxxxxxxxxxxxx
>>>>>>> Subject: [SI-LIST] Re: Impedance Controlled Board Production Vs
>>>>> Normal
>>>>>>> Board Production
>>>>>>>
>>>>>>> Suppose as you like.  Hope as you might.  What you don't
>>>>>>> contract
>>> is
>>>>> not
>>>>>>> guaranteed.
>>>>>>>
>>>>>>> Steve.
>>>>>>> On 1/2/2012 5:56 AM, Jayasuryan KG wrote:
>>>>>>>> Dear Experts,
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Happy New Year!!
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> I have question regarding the impedance controlled board
>>> production!
>>>>>>>> Is there any special process to produce impedance controlled
>>> board
>>>>>>>> rather than the normal production?
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Suppose if I go with normal production for a  impedance
>>> controlled
>>>>>>>> board
>>>>>>>> (the design has been done to meet the impedance) what are the
>>>>> possible
>>>>>>>> issues can happen?
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Looking for your immediate response. Thanks in advance.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Best Regards,
>>>>>>>>
>>>>>>>> - Jayasuryan
>>>>>>>>
>>>>>>>>
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>>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Steve Weir
>>>>>>> IPBLOX, LLC
>>>>>>> 150 N. Center St. #211
>>>>>>> Reno, NV  89501
>>>>>>> www.ipblox.com
>>>>>>>
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>>>>
>>>> --
>>>> -Michael.
>>>>
>>>> We will either find a way or make one   - Hannibal
>>>>
>>>> In the middle of every difficulty lies opportunity   - Al Einstein
>>>>
>>>> If you think you can do something or you think
>>>> you can't, in both cases you are probably right   - H Ford
>>>>
>>>> If you're not getting the results you want with the current approach,
>>>> move on and try something else.  - A. Fleischmann
>>>>
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