So the stencils for the (first) test boards arrived – yay! The stencils were from OSH Stencils and of the polyimide film type. I had no need to invest in stainless steel versions, and if the polyimide film works for test purposes then all the better! Solder was ChipQuick SMD291AX50T3 Sn63/Pb37 No-Clean T3 solder paste – liquidus temperature @ 183 °C – what I have at hand.

Thus to the question: does the oven work? Yes! 

The board in question is an NMdS HV Nixie PSU that I had made up a little while back – see: http://desmith.net/NMdS/Electronics/NixiePSU.html. I had ordered a couple of boards and two board’s worth of parts, and therefore already have an operational version that I had soldered by hand.

(This “spare” board is basically the result of a glass or two too many of wine from the effort for the first board. For the first board I soldered both the IC and the electrolytic cap around the wrong way. The cap blew, and no doubt also did the switching converter. Thus I replaced both parts on the first board from the parts for the “second” board, and everything was fine. But it left me short for parts for this second board without ordering more parts… And thus ripe for a test through the oven!)

For viewing interest I’ve attached some photos. I don’t have either a macro lens, nor a photographic microscope set-up, which is a pity! Upon looking at the solder joints with a 20x loupe under a 7x magnifying lamp they look good indeed. So it’s a   result for a first board through an oven. Indeed where is the ‘happy dance’ emoticon when one needs it!

 

Below is the temperature profile for the soldering run.

The figure is much the same as the other figures, but I’ve not included the raw profile temperature delta/differential trace. It was simply too noisy, so only the 0.01 Hz filtered trace. The only explanation I have for the “noise” in the signal is that the oven now has its hood on (read: external case). I can’t say why it has this effect, but it certainly didn’t seem to affect the final result of what appeared to be a well soldered board.

 

See the next post: Reflow oven – real board 2