How can I remove tenting on vias after assembly for debugging?

I have two BGA parts on a PCB, with a 32 bit wide bus with a few control lines and a clock line connecting them. Almost all of these traces are only on internal layers. There looks like a signal integrity problem on the bus. The good news is that the board only has parts on one side, and all the vias are through-all. Can anyone suggest good ways to remove the tenting over the vias so they could be probed with an oscilloscope, or at least be able to solder 30 gauge wire to them?

PCB Assembly
December 1, 2023

Use a fiberglass brush pencil.
Or try a small brass wire brush before practicing on a scrap board first. It would be best to get control of the brush by chucking it in a drill press (or mill if you have one) and use a heavy solid block of material (a cast iron angle bracket if you have one) and double-face tape the board to the angle bracket.
Certain more aggressive flux removerswill, with sufficient time and agitation, also remove the solder mask. If very thin traces are involved, this might be safer than using a fiberglass or brass brush.

Oliver Smith

Oliver is an experienced electronics engineer skilled in PCB design, analog circuits, embedded systems, and prototyping. His deep knowledge spans schematic capture, firmware coding, simulation, layout, testing, and troubleshooting. Oliver excels at taking projects from concept to mass production using his electrical design talents and mechanical aptitude.

Oliver Smith

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