Hey guys,
I’m going to need to put a few power-pad parts on some circuit boards soon, so I’m thinking this might be a good use for the reflow oven. What resources are out there for figuring out how to do this?
I’ll probably skip the stencil and just use a syringe with paste. The backup plan is hot-air reflow, but if the oven can do a good job, I’d like to try it.
Thanks!
–Daniel
If you can find a reflow profile for the parts you are putting down, that would be the best way to program the oven. Usually there is a ramp up to a soak temperature, a hold at soak for preheat, then a ramp up to the reflow peak, short hold there, and then a controlled ramp down.
You could use this profile as a guide, assuming that you are not going Pb-free solder on your design: Mixed-signal and digital signal processing ICs | Analog Devices
Thanks! Yeah, I’m familiar with recommended solder profiles, but my fear is that I will end up wasting a bunch of hours trying to figure out the specific machine and its quirks. Am I making this too complicated? Is it pretty self-explanatory on that front?
I regret not seeing this thread sooner considering that it’s probably too late now. Nevertheless, I’ll comment for posterity as always.
The oven does have issues you have to account for, but it can still do a good job.
You’re probably still making it more complicated than necessary though, as you suggested. I’d say just use the lead-free profile with leaded solder, don’t do multiple runs without letting the oven cool between runs (10 minutes? 30?) and don’t try to use the outer 2 or 3 inches of the tray. That’s probably sufficient to get good results, but it’s really unfortunate that you can’t see inside to know when/whether all parts have reflowed as there’s still a chance of getting bad joints due to the almost completely open temperature feedback loop. If you have a big part with good insulation and a large heat capacity, you may still have trouble with it.
Worrying about reflow profiles is mostly just for large production runs when you want to maximize yield, which means you refine the process to a point that you minimize as much as possible the number of boards that come out requiring some hand rework. For small runs, your two primary (only) concerns are whether the temperature gets high enough at each joint to melt the solder, and whether the temperature gets high enough on any part to damage it. On this oven, the lead free profile barely gets hot enough to reflow 63/37, so I’d not worry a bit about damaging parts that are lead-free reflow safe. Anyway since the oven doesn’t regulate temperature properly, any profile you program is not going to run as programmed.
If you’re doing so few parts that you don’t mind applying paste with a syringe, then it’s probably just as well to use hot air. But then you wouldn’t get to play with the reflow oven and I wouldn’t be caught dead telling someone to avoid trying something new just because there’s an easier or quicker way.