Conductive ink stops dispensing on long jobs

[Steven_Hines]

I have a board the takes about 32 minutes to print. For the first 13 minutes everything is fine, but then at some point the ink slows down and ultimately stops dispensing. I was lucky once and caught the problem quickly. I stopped the job, removed and reprinted the conductive ink, and restarted the print, and it ran fine and completed. So, it’s not a clogged nozzle. Another time, it stopped twice, once at 14 minutes and again 4 minutes from the end, with the same solution. The first time this happened I wasn’t watching and I had to wipe off the entire board and start from scratch.

From this point on, I will print the board in 3 sections to avoid this problem. But is there anything I can do to the ink settings to fix this? I assume it has something to do with the pressure in the ink cartridge slowly falling during the print.

[jazozaya]

Hi @Steven_Hines,

32 minutes ? That’s awesome.

Can you take apart your dispenser and take a look at your ink cartridge? It is possible the piston seal in that cartridge has broken. A little bit of ink crawling up the piston edges is normal, but excessive amounts of ink is not. From your description I do not think this is happening but just in case.

One parameter that you can adjust is the Rheological setpoint. We explain what each parameter does here. But long story short - increasing this parameter will increase the ink flow over time.

This parameter is quite sensitive, in the example below I’ve increased it to 0.20 for the ExcitableSnail profile. Can you give this a try? If you still have issues - try 0.21 or 0.22.

One important thing:

I stopped the job, removed and reprinted the conductive ink, and restarted the print

The V-One can detect when the probe is ON or OFF but it cannot detect when the dispenser is mounted/removed. So if the system has performed the switch calibration and you then physically remove the dispenser, it is important to force the system to re-calibrate. If it does not re-calibrate, your height will be off and you risk broken nozzles.

Clicking the ‘Home’ icon or pressing Alt+R to release the motors will force the system to re-calibrate the next time you click ‘Start’

[Steven_Hines]

Great, thanks for the quick reply. I’ll try changing that set point and see if that fixes it.

Also, yes, when I remove and replace the ink cartridge I do hit “home” so it recalibrates.

On a side note, there’s a small bug in the software during the print workflow: if you go all the way to the ink dispensing step and find that alignment is not good enough (happens to me a lot), you have to go back to the alignment stage and re-align, and then test alignment by moving to a few features. All that works fine. But the next step is to probe height. The software allows you to skip this probe step (because you already did it first time through). If you do skip, the carriage is not returned to it’s home location. Thus, when you are later prompted to put the ink dispenser in for printing, you can’t, because the carriage is so close to the PCB. Instead you have to hit Home to return the carriage first. (Given that changing alignment can change the location of holes encountered during the z probe step, it might be better to force a reprobe.)

[troy]

Thanks for the bug @Steven_Hines. I’ll prioritize it highly.

[sh00ter]

I’m facing some similar issues. Here is my point:

• After calibration the printing start correctly
• After a while the ink seems to flow to much and I’m forced to reduced the flow
• After small lines are printed, the flow is too low and stops for the big parts (components footprint for example)

During printing I’m forced to adjust every minute the flow rate of the ink. I’m not sure I’m doing it right…

I’m working on large boards with small nozzle (blue one, 150µm) to print boards with small pitches.