Can Microwaves Fuse Metal Particles on a Plastic Substrate?

[taylaron]

Greetings!
I'm interested in depositing a Line of fine copper powder on a plastic substrate. Due to Limitations of my situation, I want to explore the possibility of using tuned microwaves to fuse the copper particles to form a continuous conductive path. I'm aware microwaves bounce off metal. Is this a property of all microwave frequencies and Wavelengths or can I tune my magnetron to the resonant frequency of copper atoms like existing microwaves vibrate Hydrogen atoms in Water at their resonant frequency to heat the object?

Thanks,

 

[berkeman]

Greetings!
I'm interested in depositing a Line of fine copper powder on a plastic substrate. Due to Limitations of my situation, I want to explore the possibility of using tuned microwaves to fuse the copper particles to form a continuous conductive path. I'm aware microwaves bounce off metal. Is this a property of all microwave frequencies and Wavelengths or can I tune my magnetron to the resonant frequency of copper atoms like existing microwaves vibrate Hydrogen atoms in Water at their resonant frequency to heat the object?

Thanks,

There are other ways to put down a copper line on a plastic substrate. Using microwaves and high power to do it seems a bit dangerous and overkill. Have you considered alternate ways to accomplish your goal? Can you say a bit more about your project?

 

[taylaron]

Hi Berkeman. In short, I'm exploring possible methods of creating traces for 3D printable circuit boards. I tried to focus my question because 3D printed PCB's could consume a whole website, let alone a thread. It's out of the scope of this thread...

Conductive ink or filament for FDM printing is very expensive, so I'm trying to avoid it. I've explored alternatives such as using a roller to apply copper wire or ribbon (at room temp), but the intricacies and points of failure are very numerous in addition to simple limitations.

If I printed a layer of ABS plastic with recesses wherever there are copper traces and then fill those recesses with copper powder. Because the layer doesn't need to be that thick, it should quickly fuse under exposure to microwaves. ABS plastic doesn't fare well under microwaves, so I'm hoping the ABS won't get too hot or burn before the copper fuses.

-Tay

 

[SteamKing]

Hope is not a plan.

Does the plastic have to be ABS? Do you absolutely need copper for the conductor? What about using solder? You realize, of course, that solder has a lower M.P. than copper? How about conductive ABS filament?

https://www.amazon.com/dp/B00AF2L0W0/?tag=pfamazon01-20

 

[sophiecentaur]

Problem is that you are dealing with a good conductor and a good insulator, neither of which will absorb EM well. Is there not some approach involving electrolytic deposition I.e. using some Chemistry to help you?
Sounds a really attractive goal, though. The Philosopher's Stone, almost.

 

[berkeman]

Hi Berkeman. In short, I'm exploring possible methods of creating traces for 3D printable circuit boards. I tried to focus my question because 3D printed PCB's could consume a whole website, let alone a thread. It's out of the scope of this thread...

Conductive ink or filament for FDM printing is very expensive, so I'm trying to avoid it. I've explored alternatives such as using a roller to apply copper wire or ribbon (at room temp), but the intricacies and points of failure are very numerous in addition to simple limitations.

If I printed a layer of ABS plastic with recesses wherever there are copper traces and then fill those recesses with copper powder. Because the layer doesn't need to be that thick, it should quickly fuse under exposure to microwaves. ABS plastic doesn't fare well under microwaves, so I'm hoping the ABS won't get too hot or burn before the copper fuses.

-Tay

Have you looked at PCB Milling Machines? I've used them in the past for prototypes in our R&D Lab, and they work pretty well for simple 2-layer PCBs:

http://www.lpkfusa.com/pcb/?gclid=CLGZlpmturkCFYZ_Qgod1DgAdg

 

[taylaron]

How about this:
A wire traces are formed out of copper powder on top of an ABS 3D printed part. The entire part (ABS & copper) are then exposed to an inductive heater which will only heat the copper because ABS is not conductive. After a short time when the ABS powder has fused into a continuous trace, the inductive heater is switched to 180 degrees out of phase (still exposed to the ABS and Copper) and the part is then cooled* using induction.

After heating something can I take the heater 180 degrees out of phase and cool it? The vibrating molecules would still be vibrating in the orientation of the propagating EM waves, so taking the EM waves 180 out of phase should return the part to it's original temperature, correct?

-Tay

 

[sophiecentaur]

You cannot cool by antiphase excitation because the heating is due to quadrature (lossy) components. It cannot operate like laser cooling. If this system.worked, they'd have fridges based on it.