Electronics > Beginners
Manual (dumb) toaster-oven reflow parts recommendations?
jmelson:
--- Quote from: RL_Tracksuit_Electro on January 19, 2020, 06:46:25 pm ---Thanks for the tip, I want to try this but you seem to imply leaded paste is necessary...
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Nope, I use mostly lead-free solder. Some work well, some don't. I have found GC10 to be simply amazing, and now even use it where leaded solder could be used, as it works so well. You do have to get just a little hotter for the lead-free to reflow. I peak at 235 C to 245 C depending on the board
with the GC10 paste.
Jon
jmelson:
--- Quote from: RL_Tracksuit_Electro on January 19, 2020, 06:46:25 pm ---
I have lead free but advertised as "low temp", the tube says melting point 137C/278F.
https://www.amazon.com/gp/product/B017RSGPI8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
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I tried some of this with a temperature-sensitive component, it was horrible. It was so brittle that a mere touch with a fingernail would flick the
part off the board.
Jon
jmelson:
--- Quote from: Peabody on January 20, 2020, 02:58:04 pm ---
And finally, what I've found is that even with a syringe it's almost impossible to keep from putting too much paste on. So if you can use a stencil, that will really help.
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YES, paste application is the SECRET to reflow! I have to reduce the size of the stencil apertures smaller than the pads, and the smaller the
lead pitch, the more the apertures need to be reduced. Then, I use a 3 mil brass stencil (~0.075 mm) to keep the paste volume down. SOIC parts are really forgiving, but anything smaller, like SSOP or QFP parts are likely to form bridges with too much solder.
Jon
RL_Tracksuit_Electro:
--- Quote from: Peabody on January 20, 2020, 02:58:14 am ---It was shorthand for the melting point. For leaded solder that's 183°C, which is a lot higher than your low-temp paste. So the hot plate would certainly be hot enough. You would probably want to cut back on the "on" time periods. I don't know if low-temp paste is any good.
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I have only done about 100 joints with the stuff I linked to, but with the hot air station I've been satisfied with the results with this solder, and even did some very tight pitches I was nervous about. Once I learned the right airflow, distance, etc. (the right "touch") seems fine. Just tedious.
I'm hoping the hotplate approach will make it easier, we'll see how it goes as opposed to the hot air approach.
Peabody:
If you're going to use the low-temp paste, then I think you may need to recalibrate my On times. Basically, the solder should not melt during the soak phase, and actually should not melt until just after the second On stage has shut down - the temperature will still be increasing at that point (see my graph in the repo). And for each test, you have to start with everything at room temperature.
I don't think you have to do the tests using SMD parts. I think you can just put a few small blobs of solder on an old piece of PC board, and see when they reflow. They would reflow at about the same time if a part was present - maybe just a hair later. Anyway, if the low-temp stuff works, you'll have plenty of leeway on temperature without damaging any parts.
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