Best way to remove copper from a PC board.

I have a systron donner freq counter I want to modify to use LEDs instaed of nixies. I really like the nixie tube readout but I am having to replace the drivers too often. My plan is to remove the tracks connecting the 7490 counters to the nixie drivers and to etch away the connections to the nixie tubes leaving the pads around the holes for the drivers. Replace the nixie drivers with 7 segment decoder/drivers and rewire wire wirewrap wire. My trouble is removing the old copper. I dont want to dip the whole board. Im thinking of applying small aounts of Nitric acid to the traces.


Reply to
Jimmie D
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Cut the traces with a surgical knife and peel away the copper.


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Or use a Dremel with a very small burr to cut the traces.

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or small amount of ferric chloride painted on with a small paintbrush.

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As others have said, using a small (very sharp) exacto knife to remove the necessary conductors is usually the cleanest way. That is, as long as you don't have a bunch of modifications.

The other thing to note is this: You do not have to remove the entire trace. Just make a big enough cut (interuption) to break the electrical connection between the two pads.

I have fixed MANY PCB's this way. I use to be a manufacturing engineer at a small electronics fabricator.

Reply to
Wayne P. Muckleroy

assemble the new displays/drivers on an ancillary board that fits within the volume/space of the old nixies (they are rather cumbersome eh?)

that can be done wire/wrap or fancy dancy etched effort.

remove the nixies via solder sucker

find the right places to hookup the new displays and point to point connect.

physically secure the new display in place with best method (i use hot melt glue for retrofits on hacked equip/ sometimes brackets as required for strength)

you're doing the fitting, ( so u know best how much G-forces it will sustain)




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The traces are plated, I think Au, Ferric Chloride left on them all weekend did touch it.. I was loking for something easier than cut and peel and wanted all of the old wiring removed if practical. I have used ferric chloride before on bare Cu traces and it works if you can keep it moist and give it enough time.

I have made a display assembly using wirewrap dip sockets and vectorboard. I really dont like the looks of the wire wrap pins and will probably go back to soldertail

I have found some incandescent 7 segment displays, I really like the way these look and will probably go with them instead of LED. I have experience with them and know they can last for decades, much better than the nixies and 74141drivers.

The displayboard will have eight digits, about 60 wires, can you think of anyway to reduce the possibility of wiring errors, I am consideing using color coded wires from the driver to the display.


Reply to
Jimmie D
60 wires?

use a IDE type cable, perhaps 2 32 wire wide floppy disk IDE style.

u can count them as you position to solder and fit

some flat scsi cables have colored codings

some CAT5 network cable has clear color marking on length of entire cableset

make a plan, make a clearly written sheet PRIOR to doing any soldering, check it twice, perhaps three times, (on separate days)

even the new BIG led displays are easier to drive, but you may have trouble finding the right signals to do it if the equip is using nixies (thats pretty old stuff!)







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