1
\$\begingroup\$

I have assembled 1000 pcs of PCB. 6/1000pcs have track broken (bottom layer) as pointed in the attached picture. The pad with track connected to an electrolytic capacitor. There are two other capacitors have the same footprints with not track break.

The assembly using wave soldering machine. Temperature 260 C. The board is FR4 1.6mm thickness 1/2 Oz. ENIG surface finish. What could be the cause to avoid track break when go to 300,000 pcs??

Broken Track

Capacitor with the Pad

\$\endgroup\$
9
  • 1
    \$\begingroup\$ Half ounce copper? \$\endgroup\$ Sep 13, 2020 at 8:54
  • \$\begingroup\$ Yes, it is half ounce copper. \$\endgroup\$ Sep 13, 2020 at 9:05
  • 1
    \$\begingroup\$ Maybe try using teardrop shaped pads for through hole parts? Something like this: quadcept.com/en/manual/pcb/images/20151013134916730-19.png It helps with problems related to narrow tracks breaking off from large pads. Altium has inbuilt feature for generating it. \$\endgroup\$
    – desqa
    Sep 13, 2020 at 10:37
  • 1
    \$\begingroup\$ well, thinner things break more easily, and it takes less of a production variation to make it non-functional, too. \$\endgroup\$ Sep 13, 2020 at 10:44
  • 1
    \$\begingroup\$ 1/2 oz, 1 oz? Is the confusion because a board for PTH usually uses 1/2 oz copper laminate, which then gets plated up to 1 oz when the holes are plated through \$\endgroup\$
    – Neil_UK
    Sep 13, 2020 at 11:19

1 Answer 1

3
\$\begingroup\$

Unreliable traces are usually a problem with the PCB itself, not caused by soldering.

So, review your PCB production data (Gerber files) and make sure the copper of that traces continues under the ring of the via. Look at the ring of a board that's not soldered with a strong magnification (microscope?) to see whether there's anything suspicious. Also, look at the whole trace, not just the ring. If that't the case, contact the company that prints your PCBs, and explain the situation.

I really don't see any other reason the trace would break if it was not badly executed by the PCB factory.

\$\endgroup\$
2
  • \$\begingroup\$ I have contacted the PCB factory, however, I am not convinced with their answer. They argued that, the capacitor has gone under mechanical stress (pressed) that make the track in the bottom layer to break. As I mentioned I have 2 other capacitors didn't have trace break. \$\endgroup\$ Sep 13, 2020 at 9:02
  • 3
    \$\begingroup\$ They are implying that their via isn't strong enough for this usual use case; this might be a good argument for switching factories. Contact one of their competitors, and explain that you've been having a problem with your design, and whether they think they'll have the same problem when you order 300,000 or whether they have any feedback how to improve your design for their fabrication process. Your PCB manufacturer should be working with you, not against you. \$\endgroup\$ Sep 13, 2020 at 9:11

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.