0

I have some PCB's that I have ordered from China. The PCB has a BGA component along with traces which go from the BGA component to another BGA IC(USB controller) and finally to USB. Right now I am very interested in 2 lines on a PCB. I think I can find the trace which is going but it is insulated. I dont want to cut the trace and bring out a wire and reattach the wire to the other part of a trace to probe the line on my Logic Analyzer. Is there any other chemical which will easily remove the insulation and expose the copper and help me probe the trace? What are the alternative I have?

red car
  • 345
  • 1
  • 2
  • 11
  • 2
    Add probe points in your next design, especially when prototyping. – Arsenal Nov 23 '15 at 09:18
  • I am reverse engineering a working I2C interface. It isnt my PCB, and the register set isnt working for me correctly. I want to see the actualy I2C data which I am supposed to send – red car Nov 23 '15 at 09:23
  • 3
    Possible duplicate of [How to remove solder mask?](http://electronics.stackexchange.com/questions/81723/how-to-remove-solder-mask) – Arsenal Nov 23 '15 at 09:30
  • Not really. Even if I remove the solder mask, how do I get the probe to clip correctly? I have to solder a wire which is tough given traces are so small – red car Nov 23 '15 at 09:36
  • There must be some vias I believe. – Oshi Nov 23 '15 at 09:55
  • You can imitate an oscilloscope probe with a probe holder (if you can't use that) by clipping a sharp cut wire into your clip and put that on the copper trace - not the best and most reliable solution, but it gets the job done. After removing the solder mask there is a tiny step against which the wire can hold. But that isn't part of your question (maybe implied by the title, but the body doesn't contain it). – Arsenal Nov 23 '15 at 09:57
  • I²C requires pullup resistors. That would provide you with easy to reach probe points. – Turbo J Nov 23 '15 at 10:13
  • Internally pulled up by the IC – red car Nov 23 '15 at 10:19
  • @Arsenal, It is a Logic analyzer, and it requires it to be pretty steady. clip the probe to a wire, and glue the wire to the board – red car Nov 23 '15 at 10:21
  • 1
    Best chemical for the job is iron with 1% or so of carbon. Heat treat to harden and temper, and use abrasives to bring it to a sharp edge. Then you can scrape the insulation off and solder to the copper. –  Nov 23 '15 at 10:58

1 Answers1

1

Solder mask is some sort of thermoset polymer. Solvents for that sort of stuff are nasty. Look for a mechanical solution instead. Steel tools can scratch the mask off without damaging much the copper.

Ricardo
  • 6,134
  • 19
  • 52
  • 85
Jasen Слава Україні
  • 31,874
  • 1
  • 31
  • 65