Fixing smd pads.

Tool suggestions, soldering tips, general useful electronics knowhow.
User avatar
arkadiusz.makarenko
Posts: 92
Joined: Wed Jun 19, 2019 7:36 am
Location: Edinburgh

Fixing smd pads.

Post by arkadiusz.makarenko » Mon Aug 19, 2019 7:01 pm

Hi
I have one board which I messed up a little.
I took few caps with pads. Now how would I go and fix it?
Do not trust people. They are capable of greatness.
~ Stanislaw Lem

User avatar
exxos
Site Admin
Site Admin
Posts: 7891
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Fixing smd pads.

Post by exxos » Mon Aug 19, 2019 7:21 pm

Probably be a good idea to post images of your exact problem.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

User avatar
arkadiusz.makarenko
Posts: 92
Joined: Wed Jun 19, 2019 7:36 am
Location: Edinburgh

Re: Fixing smd pads.

Post by arkadiusz.makarenko » Mon Aug 19, 2019 7:58 pm

exxos wrote:
Mon Aug 19, 2019 7:21 pm
Probably be a good idea to post images of your exact problem.
Sorry I don't have this board just now.
It is Amiga 1200 board without three capacitor pads. I am slowly getting courage, knowledge and required equipment to fix it.

I was thinking to use UV solder mask to fix in place new cut pieces of copper which would be paid and a little bit of a trace. I am not sure if this would be strong enough to keep cap on place?
Do not trust people. They are capable of greatness.
~ Stanislaw Lem

User avatar
PhilC
Moderator
Moderator
Posts: 1822
Joined: Fri Mar 23, 2018 8:22 pm

Re: Fixing smd pads.

Post by PhilC » Mon Aug 19, 2019 8:38 pm

If you aren't too worried about originality then you could change the caps to a through hole type and solder it to the next good point?
If it ain't broke, test it to Destruction.

go0se
Posts: 94
Joined: Sun Nov 25, 2018 7:55 pm

Re: Fixing smd pads.

Post by go0se » Mon Aug 19, 2019 9:36 pm

arkadiusz.makarenko wrote:
Mon Aug 19, 2019 7:58 pm
exxos wrote:
Mon Aug 19, 2019 7:21 pm
Probably be a good idea to post images of your exact problem.
Sorry I don't have this board just now.
It is Amiga 1200 board without three capacitor pads. I am slowly getting courage, knowledge and required equipment to fix it.

I was thinking to use UV solder mask to fix in place new cut pieces of copper which would be paid and a little bit of a trace. I am not sure if this would be strong enough to keep cap on place?
CW2500 will hold the new pad and trace in place reasonably well. Be sure to give it plenty of time to set i.e. significantly longer than the packaging suggests. It can be baked as well but that's not an effective substitute for time in my experience.

https://www.digikey.co.uk/product-detai ... ND/1929217

You can buy copper foil/tape to create the new pad and trace but most of the available copper tends to be too thick. A more effective method is to peel back a ground strip from an old PCB and use that as the basis for your pad+trace template. It can be tricky to get enough copper off the scrap PCB in one piece however with a few attempts you should manage to get a large enough section.

It's best to use good quality fine/medical scissors to create the pad and trace rather than a blade as fine scissors can be more exact when cutting difficult shapes and the blade tends to crumple and crush the copper layer as it's hard to support.

Clean everything with IPA and make sure everything is dry and free of contamination before you start.

Make a decent overlap between the new and old trace, remove the mask and scrape the underside of the new copper to give a good contact, tin and solder them before applying the epoxy. Continuity test your new pad then leave the whole assembly for several days to a week and don't be tempted to replace the cap too early.

The replaced cap can also be bridge glued to a neighbour if there's another suitable cap or component nearby to give a bit more stability.

Best of luck.

Edit: I probably should have mentioned to have a few attempts on an old scrap PCB to get the process down before letting loose on your A1200. Old flat screen TVs tend to have plenty of surface mount electrolytic caps for you to rip the pads off and practice repairing. You will have plenty of epoxy to spare so best to get it right first before letting loose on a classic Amiga! :)

User avatar
kludge
Posts: 334
Joined: Thu Nov 08, 2018 2:05 pm
Location: Sweden
Contact:

Re: Fixing smd pads.

Post by kludge » Mon Aug 19, 2019 10:46 pm

I don’t know if this is blasphemy or not, but I wouldn’t bother with recreating the pads unless absolutely necessary. I would stick to patch wire.
A kludge is a workaround or quick-and-dirty solution that is clumsy, inelegant, inefficient, difficult to extend and hard to maintain.

My lack of focus:
[ 3 * Amiga 500 ][ Amiga 500+ ][ Amiga 600HD ][ Amiga 2000 ][ Amiga 4000/030 w/ 64 MB RAM hack ][ CD32 (NTSC) ][ VIC-20 ][ 4 * C64 Breadbin ][ 2 * C64C ][ 2 * C128 ][ Mac Classic ][ Mac Classic II ][ Mac Colour Classic ]

PaulJ_2.0
Posts: 124
Joined: Sat May 11, 2019 11:32 pm

Re: Fixing smd pads.

Post by PaulJ_2.0 » Mon Aug 19, 2019 11:25 pm

kludge wrote:
Mon Aug 19, 2019 10:46 pm
I don’t know if this is blasphemy or not, but I wouldn’t bother with recreating the pads unless absolutely necessary. I would stick to patch wire.
I agree, I just use enamelled wire and run it off to either the trace destination or if it's easier, a bit of exposed trace. recreating pads is all well and good if you want to make it look all pretty, but it serves no real practical purpose.

go0se
Posts: 94
Joined: Sun Nov 25, 2018 7:55 pm

Re: Fixing smd pads.

Post by go0se » Tue Aug 20, 2019 1:32 am

PaulJ_2.0 wrote:
Mon Aug 19, 2019 11:25 pm
I agree, I just use enamelled wire and run it off to either the trace destination or if it's easier, a bit of exposed trace. recreating pads is all well and good if you want to make it look all pretty, but it serves no real practical purpose.
Using an Amiga in 2019 serves no real practical purpose, but yet, here we all are! :lol:

User avatar
kludge
Posts: 334
Joined: Thu Nov 08, 2018 2:05 pm
Location: Sweden
Contact:

Re: Fixing smd pads.

Post by kludge » Tue Aug 20, 2019 7:09 am

go0se wrote:
Tue Aug 20, 2019 1:32 am
Using an Amiga in 2019 serves no real practical purpose, but yet, here we all are! :lol:
That’s a REALLY dangerous statement on, what used to be, a dedicated Atari forum. You have to be careful with that shit :lol:
A kludge is a workaround or quick-and-dirty solution that is clumsy, inelegant, inefficient, difficult to extend and hard to maintain.

My lack of focus:
[ 3 * Amiga 500 ][ Amiga 500+ ][ Amiga 600HD ][ Amiga 2000 ][ Amiga 4000/030 w/ 64 MB RAM hack ][ CD32 (NTSC) ][ VIC-20 ][ 4 * C64 Breadbin ][ 2 * C64C ][ 2 * C128 ][ Mac Classic ][ Mac Classic II ][ Mac Colour Classic ]

terriblefire
Moderator Team
Moderator Team
Posts: 1362
Joined: Mon Aug 28, 2017 10:56 pm
Location: Glasgow, UK
Contact:

Re: Fixing smd pads.

Post by terriblefire » Tue Aug 20, 2019 7:35 am

kludge wrote:
Tue Aug 20, 2019 7:09 am

That’s a REALLY dangerous statement on, what used to be, a dedicated Atari forum. You have to be careful with that shit :lol:
We can all agree that a ZX81 is a great doorstop though right? :)
———
I get cranky when asked to repeat myself.

Post Reply

Return to “ELECTRONICS”