Sparkfun has a tutorial for reflowing with a skillet, but would a induction cook top work as well? I’m not certain if it would damage components because of the way it works or not. If it wouldn’t damage components somehow I would think it would be perfect for reflow. Does anyone know?
(for example: http://www.newegg.ca/Product/Product.as … 6896112056 )
If you used a suitable pan, it should work, but why would you bother? A $25 electric frypan (skillet) does the job fine…
That’s a neat idea! It would heat up the components before the pcb even gets warm though so you would want to be careful of that. I’m just wondering if that would be bad or good… You’ll have to try it out and tell us how it goes.
Well, the main reason is because I want one anyway 
I had thought that it might be ideal because there are no heating elements. The ‘heating element’ is the pan/pot itself. It should be very uniform heat.
rrpilot:
…It would heat up the components before the pcb even gets warm though so you would want to be careful of that. I’m just wondering if that would be bad or good…
It could be very bad if enough of the magnetic flux got through the pan to heat up the components or PCB directly. Without doing more research I couldn’t guess if this is likely to be an issue…
I tried this before. I would say it’s hard to control the temperature setting because mine comes with a up & down button for the temperature. Not so perfect result and the cooker+pan is not cheap!
But it didn’t inherently harm any components? I would like to get one so I should try to get one that is very accurate. If it doesn’t work I can still cook with it.
There is a possible solution to the components heating before the PCB.
Copper is not ferromagnetic which you could use as an isolator between the pan and the pcb, at least I think that’s how the theory works. The induction stove heats the pan and transfers the heat to a copper sheet and then to the PCB. If you use a large enough copper sheet then you could block any magnetic field from the sides.
I am definitely for the idea of nice even heat, it would be very interesting if this all works out for you.
I may be on the wrong track, did some reading…
Apparently you need a ferromagnetic material to block a magnetic field but in that case wouldn’t the pan itself block it and only heat up the pan…
I am tempted to try this myself.
Unless the parts are magnetic, induction won’t heat them up.
Most induction plates can be set to hold a particular temperature, and the power level can be controlled to set the ramp rate.
JonChandler:
Unless the parts are magnetic, induction won’t heat them up.Most induction plates can be set to hold a particular temperature, and the power level can be controlled to set the ramp rate.
The concern is that a component contains magnetic materials in it or on the leads.
JonChandler:
Unless the parts are magnetic, induction won’t heat them up.
Not quite true - a changing magnetic field (such as that generated by an induction cooker) will induce a current in any conductor in the area, including copper. This current will generate heat. However, the primary manner that induction cookers use to heat is magnetic hysteresis losses, which is why you need to use ferromagnetic materials for the pan (not “magnetic”).
So going by what I have read so far on the net and what has been posted here, this is my guess on how this would work out:
Is that pretty much right? Is there any possibility of the magnetics harming any components?
Nakor:
- Copper will not work particularly well with an induction cooktop, which is actually ideal. - Using a proper pot or pan with the cooktop, copper clad FR4 (I guess?) would accept heat exceptionally well but would not itself generate heat. - Heat should be consistent and uniform. Is that pretty much right? Is there any possibility of the magnetics harming any components?
Copper pans don’t work well with an induction cooker since the primary heating mechanism is hysteresis loses in ferromagnetic material (eg iron or steel).
There will be a residual magnetic field on the top of the pan, and this is oscillating at some tens of kilohertz. This will induce voltages & currents in sections of the components being soldered. As for whether this is enough to damage components, I would guess not, but I would suggest using the thickest pan you have to minimize the residual field.
Ok thank you. I will have to try it with a cheap barebones Arduino clone or something. Cheap parts of some sort anyway.
MichaelN:
Copper pans don’t work well with an induction cooker since the primary heating mechanism is hysteresis loses in ferromagnetic material (eg iron or steel).There will be a residual magnetic field on the top of the pan, and this is oscillating at some tens of kilohertz. This will induce voltages & currents in sections of the components being soldered. As for whether this is enough to damage components, I would guess not, but I would suggest using the thickest pan you have to minimize the residual field.
The primary heating mechanism is the resistance of the pot. The reason that ferromagnetics work vs non ferromagnetic conductive materials has more to do with the skin effect. Ferromagnetic materials like iron and steel have a much shallower skin depth, and as a result convert more of the supplied current to heat. Hysteresis dissipation in the pot is somewhere along the lines of 10% of the total heating capasity.
No, the copper components wouldn’t heat up that much, but the amount of current these cookers are inducing could easily vaporize traces.
So I need a material that will not melt, will not pass current, but will pass heat between the pan and the PCB?
No. What I meant was that you want the pan itself to reduce the strength of the oscillating magnetic field to a level that won't damage the components. Pans designed for cooking on induction hotplates have a decent layer of steel (to absorb the energy from the magnetic field), combined with a layer of copper or aluminum to spread the heat evenly. The more expensive pans tend to be thicker and heavier.Nakor:
So I need a material that will not melt, will not pass current, but will pass heat between the pan and the PCB?
So with a proper pan type and thickness I should get nothing but heat being passed into my PCB?
Nakor:
So with a proper pan type and thickness I should get nothing but heat being passed into my PCB?
That’s the idea. There will be some residual field, but it should be too small to have an effect.