Homebrew_PCBs

I have a PCB that has a broken copper trace on it. What are some methods of repairing the trace that I could try that would be easy to perform and not break the bank?

Thanks.

Frank P.

On 7/17/2014 2:12 PM, qz9090@... [Homebrew_PCBs] wrote:

>
> I have a PCB that has a broken copper trace on it. What are some
> methods of repairing the trace that I could try that would be easy to
> perform and not break the bank?
>
> Thanks.
>
> Frank P.
>

Hello, Frank and the group--

The easiest and least expensive method is to use either a strand of
enameled magnet wire
or AWG #30 wirewrap wire to bridge the broken trace.

If possible, solder the repair wire to vias or pads on the ends of the
trace. That's
easier than scraping solder mask from the broken area, tinning the
exposed copper
and bridging the gap with solder or a small strand of wire. Holding the
bridging
wire in place, holding the soldering iron and feeding solder requires
three hands<g>.

If the broken trace handled high currents, use larger-diameter wire.

73--

Brad AA1IP

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

That's the gist of it, page 23.
<https://escies.org/download/webDocumentFile?id=49130>

ST


On Thu, Jul 17, 2014 at 8:27 PM, Brad Thompson
brad.thompson@... [Homebrew_PCBs]
<Homebrew_PCBs@yahoogroups.com> wrote:

>
> On 7/17/2014 2:12 PM, qz9090@... [Homebrew_PCBs] wrote:
>>
>> I have a PCB that has a broken copper trace on it. What are some
>> methods of repairing the trace that I could try that would be easy to
>> perform and not break the bank?
>>
>> Thanks.
>>
>> Frank P.
>>
> Hello, Frank and the group--
>
> The easiest and least expensive method is to use either a strand of
> enameled magnet wire
> or AWG #30 wirewrap wire to bridge the broken trace.
>
> If possible, solder the repair wire to vias or pads on the ends of the
> trace. That's
> easier than scraping solder mask from the broken area, tinning the
> exposed copper
> and bridging the gap with solder or a small strand of wire. Holding the
> bridging
> wire in place, holding the soldering iron and feeding solder requires
> three hands<g>.
>
> If the broken trace handled high currents, use larger-diameter wire.
>
> 73--
>
> Brad AA1IP
>
> ---
> This email is free from viruses and malware because avast! Antivirus protection is active.
> http://www.avast.com
>
>
>
> ------------------------------------
> Posted by: Brad Thompson <brad.thompson@...>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
> ------------------------------------
>
> Yahoo Groups Links
>
>
>

This is also a good rework guide I found while looking for the ESA paper:
<www.intertronics.co.uk/resource/guide1.pdf>

Keywords:
Intertronics PCB circuit board repair rework broken trace bow twist
conformal coating removal delamination soldering basics solder joint
acceptability
(just so I can find it again later).

ST

On Thu, Jul 17, 2014 at 8:58 PM, Stefan Trethan <stefan_trethan@...> wrote:
> That's the gist of it, page 23.
> <https://escies.org/download/webDocumentFile?id=49130>
>
> ST
>
>
> On Thu, Jul 17, 2014 at 8:27 PM, Brad Thompson
> brad.thompson@... [Homebrew_PCBs]
> <Homebrew_PCBs@yahoogroups.com> wrote:
>>
>> On 7/17/2014 2:12 PM, qz9090@... [Homebrew_PCBs] wrote:
>>>
>>> I have a PCB that has a broken copper trace on it. What are some
>>> methods of repairing the trace that I could try that would be easy to
>>> perform and not break the bank?
>>>
>>> Thanks.
>>>
>>> Frank P.
>>>
>> Hello, Frank and the group--
>>
>> The easiest and least expensive method is to use either a strand of
>> enameled magnet wire
>> or AWG #30 wirewrap wire to bridge the broken trace.
>>
>> If possible, solder the repair wire to vias or pads on the ends of the
>> trace. That's
>> easier than scraping solder mask from the broken area, tinning the
>> exposed copper
>> and bridging the gap with solder or a small strand of wire. Holding the
>> bridging
>> wire in place, holding the soldering iron and feeding solder requires
>> three hands<g>.
>>
>> If the broken trace handled high currents, use larger-diameter wire.
>>
>> 73--
>>
>> Brad AA1IP
>>
>> ---
>> This email is free from viruses and malware because avast! Antivirus protection is active.
>> http://www.avast.com
>>
>>
>>
>> ------------------------------------
>> Posted by: Brad Thompson <brad.thompson@...>
>> ------------------------------------
>>
>> Be sure to visit the group home and check for new Links, Files, and Photos:
>> http://groups.yahoo.com/group/Homebrew_PCBs
>> ------------------------------------
>>
>> Yahoo Groups Links
>>
>>
>>

 

I have a PCB that has a broken copper trace on it. What are some methods of repairing the trace that I could try that would be easy to perform and not break the bank?

Brad,
Thanks for your input. One of the difficulties I have is that the PCB has a coating (is it call conformal coating) of plastic on it. Obviously, making it difficult to solder anything to it.

Also, since there is a capacitor that has leaked, some of the coating has come off/up, making it difficult to see if the trace is still there or eaten away.

I don't know much about the fluid in caps and assuming it maybe corrosive...

Stefan,
When I first saw your message I was a bit confused, but now that I am looking at your link, I see that it is a 186 page PDF on PCB repair.

Thanks.

Brian,
Thanks for your recommendations, I'll have to think about how I am going to approach this repair.

A few things that are going to cause me some headaches are:

1) the one bad capacitor and the fluid it leaked (would like to remove some of the fluid on the PCB but don't want to damage the board any more).

2) the plastic (conformal?) coating on the board has bubbled up because of the fluid and is making it hard to see the damage and access the PCB

3) the area where the cap is, is in-between two small 2.5cm high boards that are perpendicular to the PCB I am trying to repair, i.e. hard to see and get my hands into for repair (I think I'll be using tweezers).


Any other input on this matter would be greatly appreciated.

Oh, I also forgot to ask. I have seen a Circuit Writer Pen. Is this kind of thing any good?

I have also seen a Green Protective Coating Pen. Does thing kind of thing work? And, is it necessary to use after my repair?

Thanks.

Frank P.

 

The bubbled coating has to go.
Usually it is not necessary to replace the soldermask, acrylic paint or nail polish will serve if you want to protect the area.

ALL the electrolyte definitely has to go and the board must be cleaned really well.
This stuff will keep on eating traces due to electrolytic corrosion.
Make sure to get it out from under components and inside via holes.
It has been known to eat inner layer traces in multi-layer boards.

The most likely spot for a broken trace is where traces connect to pads. The soldermask has to have a slightly oversize window for the pad (due to tolerances), leaving a short piece of trace exposed. This corrodes away first, on the most negative voltage rails due to electrochemistry.
It is not easy to spot the breaks, magnification is recommended.

Ideally the board should be washed (water and detergent) and well rinsed with de-ionised or distilled water, then dried.

ST