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Yeah, he definitely should use a sous vide circulator the next time.

by jsight 8y ago

SlowRobotAhead 8y ago
Too hot. Water would be violently boiling and fat too much contact on the parts in a bag under vacuum. Reflows ovens work because they allow nothing touching the parts on a level board, the solder paste melts into solder pools and the parts center themselves by surface tension over each pad. Most of the time if you are hot air soldering and the solder, flux, pad shape, and part are good, you need no positioning tool at all. The solder melts and the part just wiggles itself into place.
- jsight 8y ago
  I'm not sure why you'd say "too hot". Most sous vide circulators cannot even boil water, so it definitely wouldn't be "violently boiling". The general use is to hold a low temp (eg, 130F) for an extended period of time with little variation (ideally <1 degree F of variation). Getting the temperature stable without putting pressure on the parts, and also not getting them wet would be challenging, but probably not that much more challenging than doing the same thing in a toaster oven or other regular oven.
  - blattimwind 8y ago
    130 degrees freedom is about 55 °C which is way too cold for any reflowing to occur. Consider that the failed joints in question will routinely see 70-90 °C in normal operation.
    - jsight 8y ago
      Doh, of course. He actually needs >100 °C which would be impossible with the average sous vide circulator. Oops.
  - SlowRobotAhead 8y ago
    As someone that has done a LOT of reflow work, I'm a little confused why you are arguing such a ridiculous notion. First off, I think you confused C and F. The author wanted 170ºC in his oven, would would be outside the range of any existing sous vide and would be violent boil. Second, reflow only works because of the perfectly level and no contact of parts, they need to be free to FLOAT to their destination guided by surface tension.
    - jsight 8y ago
      Oh, sorry, I was joking initially and misinterpreted your remark about it being too hot. You meant that the required temps are too hot for the circulator, which is obvious in hindsight. Thanks for setting me straight. :) I'd still argue that a sous vide type circulator with a slight modification, a liquid with a higher boiling point, and a container for the board that doesn't involve vacuum sealing, would be better than the raw, unreliable oven in the OP. I bet it would end up costing about as much as a better solution, though.

Yeah, he definitely should use a sous vide circulator the next time.

by jsight 8y ago

Yeah, he definitely should use a sous vide circulator the next time.

Too hot. Water would be violently boiling and fat too much contact on the parts in a bag under vacuum. Reflows ovens work because they allow nothing touching the parts on a level board, the solder paste melts into solder pools and the parts center themselves by surface tension over each pad. Most of the time if you are hot air soldering and the solder, flux, pad shape, and part are good, you need no positioning tool at all. The solder melts and the part just wiggles itself into place.

jsight 8y ago
I'm not sure why you'd say "too hot". Most sous vide circulators cannot even boil water, so it definitely wouldn't be "violently boiling". The general use is to hold a low temp (eg, 130F) for an extended period of time with little variation (ideally <1 degree F of variation). Getting the temperature stable without putting pressure on the parts, and also not getting them wet would be challenging, but probably not that much more challenging than doing the same thing in a toaster oven or other regular oven.
- blattimwind 8y ago
  130 degrees freedom is about 55 °C which is way too cold for any reflowing to occur. Consider that the failed joints in question will routinely see 70-90 °C in normal operation.
  - jsight 8y ago
    Doh, of course. He actually needs >100 °C which would be impossible with the average sous vide circulator. Oops.
- SlowRobotAhead 8y ago
  As someone that has done a LOT of reflow work, I'm a little confused why you are arguing such a ridiculous notion. First off, I think you confused C and F. The author wanted 170ºC in his oven, would would be outside the range of any existing sous vide and would be violent boil. Second, reflow only works because of the perfectly level and no contact of parts, they need to be free to FLOAT to their destination guided by surface tension.
  - jsight 8y ago
    Oh, sorry, I was joking initially and misinterpreted your remark about it being too hot. You meant that the required temps are too hot for the circulator, which is obvious in hindsight. Thanks for setting me straight. :) I'd still argue that a sous vide type circulator with a slight modification, a liquid with a higher boiling point, and a container for the board that doesn't involve vacuum sealing, would be better than the raw, unreliable oven in the OP. I bet it would end up costing about as much as a better solution, though.