Repair of corroded PCB traces.

[fastline]

Dealing with some rather poorly manufactured PCBs in a servo amp board in CNC equipment. I can see a trace was previously repaired in which they were able to "tin" the trace with solder it appears. I found another trace that was suffering and had to point-to-point wire it because I could not get the copper trace to take solder at all! Under the scope, the copper was in very poor condition and was mostly powder but i abraded the trace and found some shiny copper under it, I then applied flux to the trace but only the vias would take solder.

Is there a better flux/solder/procedure to do these repairs? I know there is a tinning solution for proto boards and I considered painting some on the trace and then soldering to that?

 

[gophert]

What kind of flux are you using? What make and model soldering iron? What kind of s9lder are you using?

 

[Pommie]

Are you saying the traces are bare copper? Can you upload a picture?

Mike.

 

[fastline]

I won't be able to produce a good pic without use of the microscope. The traces indicates are those that typically hide under the solder mask of a PCB. The mask was peeling off because the trace under it has deteriorated. If PCB traces are typically tinned before the mask, that didn't happen, but I don't think I commonly see that.

The flux tested was a flux pen, type RMA rosin.

Solder tested was #66/44, 44 rosin core, and Kester 62/36/2 silver solder.

Seeing as a pro was able to successfully tin a trace, it must be possible and I am missing either some prep steps or the right solder materials.

I cannot recall my solder station brand but is a good quality hot air and desolder station. I believe I was running at 380C. It is a small trace but was still fighting to get enough heat in the trace, but I don't think increasing temp would have worked. It seemed the solder just did not want to flow into the copper. I am wondering if there is a fluid or other aid that can better prepare the copper or another combo that I could try?

 

[tomizett]

I usually find that getting good, clean, metal is the key - a fibreglass pencil (a small, stiff, abrasive brush) is really good for leaning up traces after you've scraped away the resist with a small screwdriver etc. An aggressive flux (someone may have recommendations) will help, too, as long as you clean it off properly afterwards.

I'll have to get myself some of that 110% solder....

 

[Pommie]

110% solder?

Mike.

 

[fastline]

Wow, I didn't know ball busting came standard here these days.

I guess someone should call Kester and let them know because that is WHAT THEY CALL IT. I have no idea what the numbers mean.

 

[Pommie]

Wow, I didn't know ball busting came standard here these days.

It doesn't, I was just curious what 110% solder was.

Mike.

 

[dr pepper]

Judicial use of a brass and or nylon brush on the end of a dremel might do the trick.

 

[fastline]

Mike, here ya go. You figure out why Kester uses 66/44 on their solder. Not sure it means much of anything but excuse the hell out of me for quoting it.
https://www.ebay.com/p/Kester-24-60...-Cored-Wire-Solder-Roll-Sn60-Pb40/20012037742

 

[JonSea]

I don't know what "#66/ 44" refers to, but it's not the composition of the solder.

The solder is 60% tin and 40% lead.

 

[fastline]

Yes, well aware now. I wish I could turn back time so we can all sleep better!

 

[JonSea]

Chill out guy. People asked an honest question.

 

[tomizett]

Wow, I didn't know ball busting came standard here these days.
I guess someone should call Kester and let them know because that is WHAT THEY CALL IT. I have no idea what the numbers mean.

Sorry ! Sorry! My fault - no offence was meant.
I didn't know if it was a typo on your part or what they called it - it just made my chuckle. I think everyone knew what you meant though.

Didn't mean to start a fight!

 

[JimB]

I was just curious what 110% solder was.

It is a special solder for the go-getters, the sort of people who try to impress the boss by emphasising that they are giving 110% to the job.


JimB