Poor print quality can present itself in many ways; as opens or shorts in traces, as a nozzle scratching the surface or not depositing ink at all. Once you gain intuition with the V-One it is very easy to identify a poor print and correct the problem.
There are two key parameters that dictate your trace quality: your ink pressure and your print height.
This is the amount of force the dispenser exerts on the ink during dispensing. Too much pressure will lead to shorts and potentially a broken nozzle or pierced piston. Not enough pressure will lead to open circuits.
As part of the calibration step, a specific pattern is printed that consists of curved and parallel lines. If traces are too thick or too thin, the pressure buttons ( and ) will adjust the ink flow and control thickness.
You only need to click the pressure buttons once or twice before seeing a difference in trace thickness. If no ink comes out at all or far too much is coming out, then you should return to the priming step.
You can click the pressure buttons while printing to see flow changes in real time!
This is the air gap between the substrate and the tip of the nozzle. The default height is 0.08 mm (80 microns) for the silver ink and 0.14 mm for solder paste. Print height is maintained automatically during a print based on the height map generated through the probing step.
The following sections identify common printing issues you may experience:
Printing too high or ink pressure too low.
The ink does not adhere to the substrate. It balls up on the tip of the nozzle and gets periodically deposited on the substrate in clumps.
Ensure your height is set to 0.08 mm and increase the ink pressure. If this behavior persists then the nozzle might be clogged or the ink might be too cold. Wait until the ink reaches room temperature and try rotating the gear by hand to purge some ink and get good flow.
A little bit subtle but if you look closely, the ink adheres to the substrate but the trace shape doesn't quite match the motion of the nozzle. The traces will also be very narrow and tall.
It's possible you have some dried ink on the limit switches that are throwing the calibration off. Make sure to clean the limit switches. You may want to force the printer to re-calibrate the height by pressing the home icon in the top right corner of the software.
Printing too low
This is dangerous territory and a broken nozzle is usually imminent. Please review the Broken Nozzles article
If you are printing too low the ink will be getting smooshed by the nozzle, and the traces will be as wide or wider than the nozzle. You will also start to see the substrate through the the traces.
Assuming a default print height of 0.08 mm, this indicates the height calibration is incorrect. Please review the Broken Nozzles article
Trapped Air Bubble.
A small gap is seen in a trace during printing, but the nozzle never raises or stops.
Sometimes a small amount of air is trapped in the nozzle when assembling the dispenser. This results in an air bubble being pushed through during dispensing, which will cause a gap in the trace, leaving an open circuit.
Carefully inspect the circuit after printing, and use the selective print function to re-print the trace with the gap. Select the features that contain the broken area in the print preview, and click START.
Want more control when selecting features to print? Try the following!
- Click and drag to select multiple features at once.
- Holding the SHIFT key while selecting features will let you add to the current selection.
- Holding the CTRL key when selecting features will subtract them from the current selection.
Emergency Trace / Via Repair
What happens if the ink is already baked, but you've only just discovered a broken trace or via? What if you don't have time to re-print a board? You have a couple of options:
Bridge the Connection with Solder
If the trace is reasonably large, and the gap is small, you should be able to use solder wire to bridge the gap. See our Hand Soldering Guide for detailed instructions on getting the best soldering quality.
For vias, you can still bridge the gap with solder - however, you will have to drill out the via first, and solder a jumper wire through the board.
- Use a slightly smaller drill bit than you had used originally to drill the board, and carefully drill out the baked conductive ink.
- Tin the pads, as described in the hand soldering guide, on both sides of the board.
- Strip some hookup wire and feed it through the board. Tin the ends.
- Solder the hookup wire to the tinned pads.
Bridge the Connection with Conductive Ink (Hot Air Gun)
For stubborn traces that won't solder, or minor touch-ups on vias, you can bridge the gap in a minute or two with some conductive ink and a hot air gun. Hot-air-cured ink will have very poor solderability and mechanical properties, but will still be conductive.
- Manually dispense conductive ink from the dispenser to bridge the broken connection.
- Place the board on a temperature-resistant surface, and hold it in place.
- Set your hot air gun to between 200-230C (390-450F). Hotter air will cure faster, but may also damage the substrate.
- Taking care to only heat the area with the ink, hold the hot air gun close to the ink for ~ 1 minute.
- Check to see if the connection is restored. If not, repeat step 4. If after a few tries it is still not connected, you will have to re-print the board.