Author Archives: ThorMJ

QuickPCB's are printed with a silver-bearing ink; for professional circuits, that means you need to keep a few things in mind:

1. There is *no* heatsink effect. The ink conducts heat very poorly.
2. The traces have resistance (like ohms of resistance -- see below).
   --For Logic, this will work.  For sensors/power, you need to check to see if it works--
3. There is little/no wetting effect of solder; if you're not happy with the resistance of a trace, you'll need to fabricate a piece of wire to lay on top of the trace -- just tinning it won't do.
4. The adhesion of the "ink" is very poor at high temperatures; if you're jumpering something or soldering a wire to the board, it's best to solder to a component lead (the larger the better; 1210 packages are good, 0805 is marginal and 0603 will just give up with any kind of tension).
5. The "ink" is not quite flat either and it's all conductive; a 1206 package makes a good jumper for 1 trace (not two), and an 0805 package is hit or miss.
6. Soldering is more like "leading" of a stained glass -- you have to draw your iron across it to wet an area. Remember to use a low-temp solder and a temperature-controlled iron.
7. Also remember that the solder will try to pull the silver from the "ink" so keep the iron on for just 1-3 seconds per joint.

The R_Check board

I printed the R_Check board to give a real-world gauge of resistance (yes the "ink" does have specs, but toying with Ohms/mm is kind of like working with board feet of lumber); from my testing:

• 0.010" traces have 1.13 Ohms/inch
• 0.012" traces are about the same
• 0.024" traces are 0.50 Ohms/inch

If you tin them:

• 0.010 / 0.012" traces didn't change much (I got ~1.05 Ohms/inch)
• 0.024" traces dropped to 0.39 Ohms/inch (0.30 if you re-tin by hand)

I did the tinning as part of the paste-solder-reflow (I can put parts on the board and send you completed boards, but that's going to cost more than $20 -- and the solder paste has a "stencil time" of 2 hours, so shipping a pasted board won't work very well). I then re-tinned with an iron to "spread the solder by hand."

Close-Up of the tinned traces

If you've wanted a quick-turn PCB (not willing to wait 2 weeks for OSHPark), and are willing to live with some limitations:

• No thru-holes, SMT only, only copper layer (no soldermask or silkscreen)
• Single-Sided, 4" x 5" boards (or 3" x 4" boards)
• Traces are conductive ink (works well, but I wouldn't do high currents without tinning or adding a wire)
• Larger sizes & spacing than a copper PCB: 
  • Minimum trace width: 0.2mm / 8 mil
  • Minimum passive size: 1608 [metric] / 0603 [English]
  • Minimum spacing: 0.8mm / 30 mil
• Need to use a temperature controlled iron (ideally, use Sn62 alloy @ 215c / 420F)

I can get you PCB's in 2-3 days (you send the file and PayPal the money, I drop the boards in USPS post as soon as they're done) -- faster if you're in the Atlanta area, especially if you get me the files before noon!

$20/1, $30/2 and $40/3

Send your inquiry to , and I'll get it shipped to you quickly.

Initial Hello World PCB (a 555 timer blinking some LEDs):