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'[EE] Repairing lifted PCB pads'
2010\11\30@133444 by Philip Pemberton

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Hi guys,

Does anyone know what type of glue is typically used for reattaching lifted PCB pads?

I've got a batch of boards which are having pad-lift issues when parts are removed and replaced. These are boards from Gold Phoenix; the boards from Eurocircuits are fine (and seem to have a FAR better quality solder mask -- not as nice looking, but MUCH more resistant to heat -- and they don't tend to delaminate like the GP boards).

This means I have a board where I've had to replace the FPGA (bad soldering blew the chip) and where a few pads have lifted as a result. Given the option, I'd rather greenwire the broken pads (they're nearly all grounds near decoupling caps), glue the lifted pads back down and put the boards back into use. Scrapping a board with nearly £100 worth of parts on it seems really, REALLY wasteful when the only problem is a few lifted pads.

Thanks,
-- Phil.
spam_OUTpiclistTakeThisOuTspamphilpem.me.uk
http://www.philpem.me.uk/

2010\11\30@134841 by Mike Harrison

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On Tue, 30 Nov 2010 18:34:40 +0000, you wrote:

{Quote hidden}

I don't think there is anything practical that will re-fix small pads and also withstand soldering
heat - I'd just cut any lifted copper to stop any further peeling and hardwire where necessary.

2010\11\30@150427 by Dave Tweed

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Philip Pemberton wrote:
> Does anyone know what type of glue is typically used for reattaching
> lifted PCB pads?

You should check out Circuit Rework (http://www.circuitrework.com/). These
guys can perform miracles solving problems like these, and they also sell
the tools and supplies required to do it. They happen to be local to me, and
I'm a very satisfied customer.

> This means I have a board where I've had to replace the FPGA (bad
> soldering blew the chip) and where a few pads have lifted as a result.
> Given the option, I'd rather greenwire the broken pads (they're nearly
> all grounds near decoupling caps), glue the lifted pads back down and
> put the boards back into use. Scrapping a board with nearly =A3100 worth
> of parts on it seems really, REALLY wasteful when the only problem is a
> few lifted pads.

On the other hand, if the board isn't repaired to a level of reliability
comparable to a virgin board, how do you know it isn't going to cost you a
similar amount (or more) in support later? Normally, you'd only do this kind
of repair on a board that's worth 10x to 100x as much.

If you're getting a significant number of boards that have problems like
these, then you need to fix the problems in the manufacturing process first..

-- Dave Twee


'[EE] Repairing lifted PCB pads'
2010\12\01@114945 by RussellMc
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Phil says:

> I've got a batch of boards which are having pad-lift issues when parts
> are removed and replaced. These are boards from Gold Phoenix; the boards
> from Eurocircuits are fine (and seem to have a FAR better quality solder
> mask -- not as nice looking, but MUCH more resistant to heat -- and they
> don't tend to delaminate like the GP boards).

This is an area where others will have more day to day expertise so if any
real experts pop their heads up listen to them instead. That said ...:

My comment is re the nature of the PCB, not re repairing it.

Unless something very unusual was specified the PCB material should have
been specified as FR4, and a reputable manufacturer should have used FR4
regardless if there was no spec

         http://en.wikipedia.org/wiki/FR-4

FR-4 uses multiple layers of "prepregs" which are bonded with epoxy resin

        http://en.wikipedia.org/wiki/Epoxy_resin

The only sensible probable alternative is CEM3 which is unlikely from China
(see prior post reference below)

"Proper" FR-4 is UL rated and the certification is shown within the layers
of the4 PCB.
While it is conceivable that bdifferences in manufacturing parameters of
legitimate FR-4 may make one source of material inferior, it is at least
worth considering that the PCBs may not be FR-4 at all. This leads to an
interesting chain of "what if's".
Is it certified at all, and does that matter here?
Is it made by a low cost source who does not care about materials

Gold Phoenix say  " ... All of our PCB board products are in compliance with
UL and GB (China National Standard Committee) GB4588.2, GB4588.4 and
IPC-600E standards."

Yo say "...tend to delaminate ...". Under what conditions. This sounds like
a major materials issue - certainly not one which yuou'd expect from a
certified product as claimed above.

On their technical guide page at http://www.goldphoenixpcb.biz/tech.php
they say:


CEM-3 FR4(130℃ Tg)
Rogcrs4003 FR4(140℃ Tg)
FR4(150-170℃ Tg)

Equating CEM-3 and FR4 is not encouraging as the two are fundamentally
different in layup PLUS use different chemistry resins.
I posted a longish post a few months back covering matters related to
different PCB materials and characteristics. It included some references and
may be worth looking at. I've just reposted it under subject line Re: [EE];
PCB Materials (was Parallel passives and sprinkled vias?)

Note that they list 3 different "FR4's" with temperature ratings of 130, 140
and 150-170 C.
What that means in practice may be worth finding out.
I don't know how old your PCBs are or what paperwork is still available, but
seeing what material the manufacturer used and / or if it was listed and/or
what they use or say bthey use if you don't ask or "just" say "FR-4" may be
worth knowing.
Is the base material semi-translucent / whitish / brown ? (FR4/CEM3/ugh)

If not certified FR-4, is it flame retardant? Do you care. (eg G-10).
Hopefully it is actually  fibreglass and not a paper/phenolic material.

Their "partners" Spark Fun may be able to comment usefully if GP can't or
won't.

The PCB maker MAY have some liabiliy, or MAY be prepared to provide useful
input, even if, as is likely, they both have contracted out of
responsibility as much as is possible and are not realistically approachable
legal. Reputation sometimes works and Spark Fun may provide some gentle
leverage. Maybe.


           Russell McMahon


{Quote hidden}

> few lifted pads.

2010\12\01@115955 by RussellMc

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Here's an 'independent' US rep' who lists some good claims re Gold Phoenix.
This tells what you SHOULD be able to expect

     http://www.mcdonnellenterprises.com/pcb_manufacture_assembly.htm

2010\12\01@120032 by Bob Blick

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On Thu, 2 Dec 2010 05:48:48 +1300, "RussellMc" said:
> Phil says:
>
> > I've got a batch of boards which are having pad-lift issues when parts
> > are removed and replaced. These are boards from Gold Phoenix; the boards
> > from Eurocircuits are fine (and seem to have a FAR better quality solder
> > mask -- not as nice looking, but MUCH more resistant to heat -- and they
> > don't tend to delaminate like the GP boards).
>
> This is an area where others will have more day to day expertise so if
> any
> real experts pop their heads up listen to them instead. That said ...:
>
> My comment is re the nature of the PCB, not re repairing it.
>
> Unless something very unusual was specified the PCB material should have
> been specified as FR4, and a reputable manufacturer should have used FR4
> regardless if there was no spec

I know he said "delaminate" but what I understood was not that the board
material itself was having problems, it was the copper pulling away from
the board. Both the Eurocircuits and Golf Phoenix boards could be fine
quality FR4 but the copper layer on the Gold Phoenix not attached as
well. I remember the 2-day boards from AP Circuits having copper like
that, it did not like any rework, and even before soldering you could
peel it off quite easily.

Friendly regards,

Bob

-- http://www.fastmail.fm - Send your email first class

2010\12\01@120658 by Bob Blick

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On Thu, 2 Dec 2010 05:54:02 +1300, "RussellMc" said:
> Here's an 'independent' US rep' who lists some good claims re Gold
> Phoenix.

Like an independent used car salesman?

-- http://www.fastmail.fm - Accessible with your email software
                         or over the web

2010\12\01@125148 by RussellMc

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> > Here's an 'independent' US rep' who lists some good claims re Gold
> > Phoenix.

> Like an independent used car salesman?

No. It's all in the punctuation :-).

        R

2010\12\01@133522 by M.L.

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On Wed, Dec 1, 2010 at 11:48 AM, RussellMc <apptechnzspamKILLspamgmail.com> wrote:
> CEM-3 FR4(130℃ Tg)
> Rogcrs4003 FR4(140℃ Tg)
> FR4(150-170℃ Tg)
>
> Equating CEM-3 and FR4 is not encouraging as the two are fundamentally
> different in layup PLUS use different chemistry resins.
> I posted a longish post a few months back covering matters related to
> different PCB materials and characteristics. It included some references and
> may be worth looking at. I've just reposted it under subject line Re: [EE];
> PCB Materials (was Parallel passives and sprinkled vias?)

Everything I've seen, dozens of boards from Gold Phoenix in the last
couple years has been what appears to be real FR-4.
I've not noticed any copper pull-up problems on boards that are gently
reworked a couple times. When you start getting into higher
temperatures, larger parts, larger holes, there are always issues with
reworking too much.

--
Martin K.

2010\12\01@140537 by RussellMc

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>> Equating CEM-3 and FR4 is not encouraging as the two are fundamentally
>> different in layup PLUS use different chemistry resins.
>> I posted a longish post a few months back covering matters related to
>> different PCB materials and characteristics. It included some references and
>> may be worth looking at. I've just reposted it under subject line Re: [EE];
>> PCB Materials (was Parallel passives and sprinkled vias?)
>
> Everything I've seen, dozens of boards from Gold Phoenix in the last
> couple years has been what appears to be real FR-4.
> I've not noticed any copper pull-up problems on boards that are gently
> reworked a couple times. When you start getting into higher
> temperatures, larger parts, larger holes, there are always issues with
> reworking too much.

Good to hear re GP.
Interestingly, he notes that PCB's from Eurocircuits do not have the
same problem.
Murphy says that there may be relevant missing information but it does
sound from what's said that E' do something differently.


     Russel

2010\12\01@194129 by M.L.

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On Wed, Dec 1, 2010 at 2:05 PM, RussellMc <.....apptechnzKILLspamspam.....gmail.com> wrote:

> Good to hear re GP.
> Interestingly, he notes that PCB's from Eurocircuits do not have the
> same problem.
> Murphy says that there may be relevant missing information but it does
> sound from what's said that E' do something differently.
>
>
>      Russell

Of course, I never have to do much reworking because my boards are
perfect the first time every time*
--
Martin K.
50% of the time * every time.

2010\12\01@195840 by peter green

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RussellMc wrote:
{Quote hidden}

>

2010\12\02@091948 by Olin Lathrop

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peter green wrote:
> Personally I suspect he just got a bad batch. While GP are cheap and
> generally provide good boards I think thier quality control may leave
> something to be desired. I know someone at uni got a four layer board
> from them supposedly electrically tested but that turned out to have a
> load of bad vias on it.

Interesting you should mention that.  We built 10 prototypes for a customer
using Gold Phoenix 4-layer boards.  These are supposedly electrically tested
by default.  We gave the customer several of these prototypes that we had
individually bench tested here.  Yesterday the customer brought one back
where a particular feature didn't work.  We traced it down to a bad via.
Making the connection by soldering down some thin wire fixed the problem.

This board did work originally, and was supposedly electrically tested at
Gold Phoenix.  Apparently the via was marginal, and opened up after a little
handling.

This is the first time in a bunch of years and dozens of different boards
I've seen this problem from Gold Phoenix, except one time I accidentally
forgot to check off electrical testing on a two layer board.

Is Gold Phoenix going downhill?  Do we need to look for another place to get
all our prototypes done?


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Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000

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