Author Topic: Lifted pad on PCB  (Read 1881 times)

0 Members and 1 Guest are viewing this topic.

Offline Rob Lo

  • Contributor
  • Posts: 14
  • Country: us
Lifted pad on PCB
« on: August 29, 2016, 12:37:39 am »
I was desoldering a pad this morning and,  unfortunately, lifted it. It was for a 15k resistor.
(R60)

So I was looking to repair and I've done this once before by soldering the lead to the trace the pad was connected to.

This pad, however, has no trace. The left lead of the resistor has a trace that connects to the resistor above it (r59).

I am hoping maybe it's as simple as bridging the lead of the stripped pad to one of the joints on r59?
 

Offline Macbeth

  • Super Contributor
  • ***
  • Posts: 2481
  • Country: gb
Re: Lifted pad on PCB
« Reply #1 on: August 29, 2016, 12:53:49 am »
I can only guess you are having trouble because this is a multilayer board and not just double sided? Have you also stripped the via as well as the pad? Chances are its a ground plane or power its connected to. You should be able to buzz it out with a continuity tester and find an alternative to bridge to.

But the provided information on R59 and R60 is useless without any context like pics of the other side, or what this board is.
 
The following users thanked this post: Rob Lo

Offline Rob Lo

  • Contributor
  • Posts: 14
  • Country: us
Re: Lifted pad on PCB
« Reply #2 on: August 29, 2016, 01:44:57 am »
Ahh very sorry...

It is a synth module. There is a pad on the top side also so it was a via? Not sure if I can just solder it to the top pad? I cannot see any trace from the top side of the board.

I looked at the schems and it appears that r60 is connected to an opamp (in parallel?)

I've attached a pic of the top side of the board and also the schematics.
 

Offline PA0PBZ

  • Super Contributor
  • ***
  • Posts: 3904
  • Country: nl
Re: Lifted pad on PCB
« Reply #3 on: August 29, 2016, 01:49:12 am »
I cannot see any trace from the top side of the board.

I can clearly see a trace from both leads at the top side, so just solder the resistor in and make sure you also solder them on the top side - done!
Keyboard error: Press F1 to continue.
 
The following users thanked this post: Rob Lo

Offline Rob Lo

  • Contributor
  • Posts: 14
  • Country: us
Re: Lifted pad on PCB
« Reply #4 on: August 29, 2016, 01:53:58 am »
I see the trace on the top side now as well! I dodged a bullet it seems. Thanks for the help!
 

Offline Assafl

  • Frequent Contributor
  • **
  • Posts: 577
Re: Lifted pad on PCB
« Reply #5 on: September 02, 2016, 03:32:49 pm »
For the future: If you do a lot of repairs for multilayer boards - especially with ground planes and ROHS solder - you will probably want a high power (regulated temp) soldering iron.

Low power (30W or less) soldering irons take too much time to heat up the connection which ends up with lifted pads or worse.
 

Offline Jeff_Birt

  • Regular Contributor
  • *
  • Posts: 193
  • Country: us
Re: Lifted pad on PCB
« Reply #6 on: September 02, 2016, 10:54:36 pm »
When I used to do component level repair on two sided, through hole PCB we had a repair kit to fix a lifted pad. As I recall the brand name was something like 'Circ-Kit' but I could not find it with a quick search. I did find: http://www.intertronics.co.uk/products/eyelets.htm which is similar. You insert the eyelet through the hole, and use the forming tool to form a dome/hat on the other side of the eyelet (sort of like how you form a rivet. If provides a good mechanical repair and when you solder the component back in you have a good electrical repair.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf