Induction Heater Soldering

[mfgeng10]

I am trying to solve a puzzling problem and need some help/insight. We manufacture circuit breakers. We use an induction heater to solder some small thin walled steel cans to a "header" bottom plate. The induction heater works fine for a double or triple pole unit(larger mass) but frequently fails on single pole units. What factors are critical to this operation and would cause this effect? What factors could be changed to achieve beter results?

 

[IRstuff]

How does it "fail?" Does the solder melt at all?

There might simply be insufficient coupling with a small mass to overcome convective cooling.

TTFN

 

[mfgeng10]

Just to give some more background: We are using a Ameritherm Induction Heater
Power: 3 kW
Model: Nova Star 3L
Frequency: 50-485 kHz
AC kVA: 4.5
VAC Line Input: 3-phase, 220-240
Input Circuit
Breaker: 15 A

When I say it fails, what I mean is that only half (or less) of the solder melts and flows. Sometimes the units(on ly single pole) don't heat up at all and the solder paste just sits there. You can take them out of the nest and they are barely warm. We are using a 63/37 Sn-PB rosin solder paste. I know there are many variables in this process. I'm hoping someone has had a similar problem or can point me in the direction of a solution.

 

[hacksaw]

skin depth/material thickness is a big player

 

[IRstuff]

I just spoke with an Ameritherm rep:
Gary Smith: Tel: 562-463-0677 or gsmith@ameritherm.com

He says they have an applications lab where you can try out their equipment. I would take them up on that offer and see if they can help you figure out what the actual problem is, whether it's geometry, materials, size, surface prep or whatever.

TTFN

 

[nbucska]

You may have to use a concentrator -- a specially shaped
HF transformer

<nbucska@pcperipherals.com>