Adjust the Bake time of the Conductor Ink?

[kwon]

I understand that it takes about 50 minutes for the conductor ink to cure.
I want to experiment.
Can I do soldering even if it is bake by manual at 210 ℃ and 20 minutes?

[mewertow]

Hi @kwon,

Our standard conductive ink takes 30 minutes to cure, the additional 20 minutes is accounted for the heater to cool down. I have had mixed results with curing for shorter periods of time - in some cases I’ve had solderable ink at 12 minute cure times, but it wasn’t particularly consistent. I can say that the conductivity of the ink itself is mostly set within the first 5 minutes of curing, the rest of the curing time will ensure the resin that binds the ink together is properly set. So, it may be possible to solder to ink that’s been cured for a shorter period if the ink layer is relatively thin, though the mechanical stability might not be up to scratch.

If you’d like to try it out, best I can say is to give it a go and let us know what you find!

• Matt

[Rocksetta]

@mewertow can you use a temperature controlled hot air gun to manually cure short traces of conductive ink? Is there a visual way under a microscope to tell when the ink is cured enough?

[TSS_Bill]

@Rocksetta Im sure you could cure the ink using a hot air gun but Im not sure how effective that would be. Our ink takes at least 30 minutes to cure. We have some details about that here: https://docs.voltera.io/v-one/v-one-fundamentals/curing-conductive-ink

Im very confident that you can see if an ink is cured under a microscope but I dont have any examples of that handy. If you’ve completed a Hello World then you could take a look at the cured ink on that as an example.

[Rocksetta]

Thanks @TSS_Bill I am just getting used to a 2 year old borrowed V-One.

[Rocksetta]

@kwon @mewertow

The microscope idea is a good one. I will see what I can do for pictures. If you have a well cured an OK cured and a poorly cured image that would be really useful. Like always I am messing around with settings to see if I can get better prints.

What do people think is the best test of how well the ink is cured?

1. Look under a microscope (What are you looking for?)
2. Try to solder it, well cured will be easier to solder
3. Try to scrape it off, well cured will be hard to scrape off.

Any other tests I have not thought of.

[Rocksetta]

@TSS_Bill and @cborn

So here is a microscope image ofa properly baked, new ink (The one starting with T^2). Not really sure what I am looking for but the ink does kind of look multicolor melted like a metal. I burnished it for a while, but also not really sure how to tell when it is fully burnished.

I have been trying soldering, but I think my solder tip is a bit too hot as the conductive ink sometimes pulls off the board (melts). Wondering if anyone has a method to estimate the top end temperature, as my solder iron only has a temperature dial, no estimate of the actual tip temperature.

Obviously the low end temperature would be to just melt the Voltera solder. I am wondering what a high end temperature limit test would be. I probably have some high temperature solder which perhaps the soldering iron should not be hot enough to melt the other solder.

here are a few good reads

Automatically tin prior to hand-soldering using V1-applied paste & reflow?

Got dem rewetting blues

Any other suggestions?

[Rocksetta]

@TSS_Bill @cborn

So I am doing a bit better.

When wetting the conductive ink pads I can use a super low temperature and as mentioned above no flux is needed. The iron just has to be hot enough to melt the solder. When wetting the through hole pins I used flux and a much higher solder temperature to get the solder to stick to the pin. The following image I forgot to reduce the iron temperature and melted a pad when I tried to solder the wetted parts together, but as long as I go back to a super low temperature (just enough to melt the Voltera solder I can re-solder the pin to pad without melting the pad.

A side note here: Is there a way to improve the conductive ink adhesion to the FR1 boards. Does anyone do a pre-wash with a particular solvent?

…

Day later:

Using a temperature adjustable iron. I am getting the solder to melt at 250 Degrees Celsius. But best soldering at 275 degrees. This is not even hot enough to melt regular solder, but is easier on the conductive ink. Unfortunately at that low temperature everything becomes a heat sing. flux and header pins absorbs too much of the heat. As soon as you crank the temperature to deal with the heat sinks then the conductive ink melts or comes off the board.

What I am having success with is the very low temperature and only a miniature amount of flux. Also pre-wetting headers then soldering at the lowest temperature.

Any suggestions for getting better adhesion to the FR1 boards with the conductive ink? When the ink fails it seems to pull off the board before the ink dissolves. Better adhesion would allow a slightly higher soldering temperature.