[SI-LIST] Re: Tip and Ring routing consideration

Etch width requirements in telephone line interfaces stem from the 
requirement that the copper not fuse under fault current conditions.

Steve.
At 08:06 AM 6/29/2005 -0400, k EPD wrote:
>
>
>
>
>
>I don't agree with making the etch wider meets the isoloation prarameters.
>First you have to make an 600 volt isolation criteria dictated by FCC part
>68- that mean keeping the etch between T and R away from each other in all
>directions - Second, these etches should be absolutely kept away from any
>ground or voltage planes after the transformer and/or including the opto
>device (if applicable).    Etch width is totally irrelavant , there is no
>impedance requirements per FCC rules.
>
>
>Keith Kowal
>
>Electronic Product Design epd2001usa@xxxxxxxxxxx[1]   [2]  [3]
>
>
> >From: hariharan <hariharan@xxxxxxxxxxx>
> >Reply-To: hariharan@xxxxxxxxxxx
> >To: suganthi@xxxxxxxxxxxxx, si-list@xxxxxxxxxxxxx
> >Subject: [SI-LIST] Re: Tip and Ring routing consideration
> >Date: Wed, 29 Jun 2005 16:29:30 +0530
> >
> >Hi Suganthi,
> >
> >The traces have to be wide enough (40 mil) to meet the isolation
>parameters.
> >There is a good application note with Intel about Layout consideration for
> >their E1/T1 transceivers, you can use that as reference.
> >
> >Regards
> >hariharan
> >
> >-----Original Message-----
> >From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
> >Behalf Of Suganthi
> >Sent: Wednesday, June 29, 2005 4:13 PM
> >To: si-list@xxxxxxxxxxxxx
> >Subject: [SI-LIST] Tip and Ring routing consideration
> >
> >Hello All,
> >
> >
> >
> >What consideration to be taken care for TIP and Ring (Telecom domain)
> >pair routing in PCB layout , and let me know the reason also.pls send me
> >if u have any guidelines regarding this.
> >
> >
> >
> >Advance thanks for your Help!!
> >
> >
> >
> >Regards
> >
> >Sug
> >
> >
> >
> >
> >
> >
> >
> >-------Original Message-------
> >
> >
> >
> >From: Sol.Tatlow@xxxxxxxxxxxxxxx
> >
> >Date: 06/29/05 15:12:13
> >
> >To: gzilber@xxxxxxxxxx; billw@xxxxxxxxxxx; si-list
> >
> >Subject: [SI-LIST] Re: Fixing a black pad
> >
> >
> >
> >Hi Gil,
> >
> >
> >
> >The 'Black Pad' phenomonen is well known in the industry - the root
> >
> >of the problem is generally the nickel plating applied during the
> >
> >ENIG (electroless nickel immersion gold) plating process, where a
> >
> >corroded nickel layer leads to weak solder joints after assembly.
> >
> >This phenomonen therefore only affects boards with ENIG plating,
> >
> >and although reflow temperature/profiles may exacerbate the problem,
> >
> >they are not the real cause.
> >
> >
> >
> >The worst part is, you cannot detect it optically before assembly -
> >
> >it only becomes apparent when the joints fail, as you found out.
> >
> >And, if you have this problem with one board, you will most likely
> >
> >have more boards coming back to you with the same problem, since it
> >
> >is related to the plating bath (which was no doubt used to produce
> >
> >a whole batch of your boards).
> >
> >
> >
> >AFTER failure, there is not too much you can do about it - with an
> >
> >aggressive flux you may succeed in soldering the component back
> >
> >onto the board, but since the problem is with the nickel plating
> >
> >(which, due to corrosion, allows the copper underneath to interact
> >
> >with the joint), reworks are likely to suffer a similar fate (even
> >
> >if the reworked component SEEMS to be properly soldered). PLUS,
> >
> >even if only one BGA on the board has failed, if there are others,
> >
> >they are also likely to fail at some point. The safest solution,
> >
> >if also the most expensive (short term!), is to replace the board.
> >
> >
> >
> >For the future, since finding a PCB manufacturer who can produce a
> >
> >reliable ENIG finish is easier said than done (not because they
> >
> >don't exist, rather, because you only know if they weren't reliable
> >
> >when they prove it!!), for the future you may want to consider
> >
> >immersion tin or silver. These have other disadvantages (there is no
> >
> >perfect surface finish), but they tend to give overall better results.
> >
> >The best thing to do is do some Googling/reading about the subject,
> >
> >and decide on the basis of your specific needs.
> >
> >____________________________________
> >
> >Sol Tatlow, M.Eng. (Oxon)
> >
> >ProDesign Electronic &CAD Layout GmbH
> >
> >Product Developer
> >
> >Albert-Mayer-Str. 16
> >
> >D-83052 Bruckmuehl
> >
> >Phone: +49 (0) 8062-808-302
> >
> >Fax: +49 (0) 8062-808-333
> >
> >Mailto:sol.tatlow@xxxxxxxxxxxxxxxxxxxx
> >
> >www.prodesign-europe.com
> >
> >____________________________________=20
> >
> >
> >
> >
> >
> >
> >
> >-----Urspr=FCngliche Nachricht-----
> >
> >Von: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
> >
> >Im Auftrag von Zilber Gil
> >
> >Gesendet: Dienstag, 28. Juni 2005 16:33
> >
> >An: billw@xxxxxxxxxxx; si-list
> >
> >Betreff: [SI-LIST] Re: Fixing a black pad
> >
> >
> >
> >
> >
> >Hello Bill,
> >
> >Thanks for the response. The pad finishing was ENIG and the BGA have
> >
> >SnPb solder balls. I saw the Black pad only after removing the BGA
> >
> >components that was mounted more then a year ago (due to
> >
> >disconnections). Is it possible that it is not a real black pad but too
> >
> >low reflow temp in this components (partially could soldering) causing
> >
> >to oxidation of the Ni?
> >
> >
> >
> >Thanks,
> >
> >Gil=20
> >
> >
> >
> >-----Original Message-----
> >
> >From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> >
> >On Behalf Of Bill Wurst
> >
> >Sent: Tuesday, June 28, 2005 2:46 PM
> >
> >To: si-list
> >
> >Subject: [SI-LIST] Re: Fixing a black pad
> >
> >
> >
> >Gil,
> >
> >
> >
> >I'm wondering if the black pad is silver (Ag) oxide. Have you recently
> >
> >switched to lead (Pb) free processing? Or worse, has your BGA vendor
> >
> >begun to supply you with lead free parts without your knowledge?=20
> >
> >Unfortunately, I'm not very knowledgeable when it comes to silver solder
> >
> >processes, but would like to hear from anyone else with more knowledge
> >
> >than I in this area. We may all need to learn about this quickly as the
> >
> >electronics industry makes the lead-free transition.
> >
> >
> >
> >-Bill
> >
> >
> >
> >
> >
> >/************************************
> >
> >/ billw@xxxxxxxxxxx /
> >
> >/ /
> >
> >/ Advanced Electronic Concepts, LLC /
> >
> >/ www.aec-lab.com /
> >
> >************************************
> >
> >=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
>
> >
> >=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
>
> >
> >=3D=3D=3D=3D=3D=3D=3D
> >
> >Zilber Gil wrote:
> >
> >>Hello all,
> >
> >>After removing a BGA components a black pads was seen on some of the=20
> >
> >>pads. Is it possible to fix it? If trying to use activated flux it is=20
> >
> >>possible to coat the pad with solder (receive back the wetting). Does=20
> >
> >>the black pad phenomenon will appear again on this pad (will I=20
> >
> >>encounter it later on other pads?)?
> >
> >>=20
> >
> >>=20
> >
> >>=20
> >
> >>Thanks,
> >
> >>=20
> >
> >>Gil Zilber
> >
> >>=20
> >
> >>Elta systems
> >
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