4 ms·

Depends. New work versus rework versus what-is-this-piece-of-crap?

exmadscientist 4y ago
Ding ding ding. Production soldering isn't easy, but it's much easier to dial in than rework jobs. It's definitely a desirable goal to not need flux for production work. Rework... good bloody luck.
- lightedman 4y ago
  I most certainly do not use flux in my rework. I am in a zero-clean facility, the only flux allowed is that which comes with the solder paste for stencil and SMT placement - on initial production work. Fluxless rework isn't difficult at all. I do it dozens of times a day.
  - exmadscientist 4y ago
    I'm having a little trouble believing you unless by "rework" you meant "reflow". Production reflow without extra added flux is normal. It's the goal for every assembly line anywhere and is almost always achieved. Rework of existing joints after assembly without flux is just about impossible. The oxidation of the joints guarantees it. Many times the flux in the paste or wire is sufficient, but this is more true for through-hole than for surface-mount, mainly due to joint geometry and available volumes. If you are regularly reworking old fine-pitch surface mount joints previously assembled with no-clean flux, without flux of your own... then I'd like to know what materials you're using, because that is not possible in general. The "no-clean" fluxes are notorious for causing rework trouble, and they are difficult to clean off once reflow temperatures have been achieved (that's why we call them "can't-clean"). They are never active twice, so they must be removed and replaced once heated the first time. We have to use special solvent flux removers around here (based on DuPont's hellish Vertrel XF) to get the crap off just to be able to access joints again. (This is on assembly work done out-of-house or on COTS devices, made with who-knows-what.)
    - lightedman 4y ago
      "I'm having a little trouble believing you unless by "rework" you meant "reflow"." Nope, we don't use flux at all for rework. As the majority of our boards are solid metal, we just slap them on a heater and poke the components down or slide them into place. Flux isn't needed. Even with crappy RoHS tin solder. If you're getting significant-enough oxidation that interferes with rework with the product fresh out of the oven, or even a day or two later, you're doing something extremely wrong. Check and make sure your production paste isn't contaminated.

Ding ding ding. Production soldering isn't easy, but it's much easier to dial in than rework jobs. It's definitely a desirable goal to not need flux for production work. Rework... good bloody luck.

lightedman 4y ago
I most certainly do not use flux in my rework. I am in a zero-clean facility, the only flux allowed is that which comes with the solder paste for stencil and SMT placement - on initial production work. Fluxless rework isn't difficult at all. I do it dozens of times a day.
- exmadscientist 4y ago
  I'm having a little trouble believing you unless by "rework" you meant "reflow". Production reflow without extra added flux is normal. It's the goal for every assembly line anywhere and is almost always achieved. Rework of existing joints after assembly without flux is just about impossible. The oxidation of the joints guarantees it. Many times the flux in the paste or wire is sufficient, but this is more true for through-hole than for surface-mount, mainly due to joint geometry and available volumes. If you are regularly reworking old fine-pitch surface mount joints previously assembled with no-clean flux, without flux of your own... then I'd like to know what materials you're using, because that is not possible in general. The "no-clean" fluxes are notorious for causing rework trouble, and they are difficult to clean off once reflow temperatures have been achieved (that's why we call them "can't-clean"). They are never active twice, so they must be removed and replaced once heated the first time. We have to use special solvent flux removers around here (based on DuPont's hellish Vertrel XF) to get the crap off just to be able to access joints again. (This is on assembly work done out-of-house or on COTS devices, made with who-knows-what.)
  - lightedman 4y ago
    "I'm having a little trouble believing you unless by "rework" you meant "reflow"." Nope, we don't use flux at all for rework. As the majority of our boards are solid metal, we just slap them on a heater and poke the components down or slide them into place. Flux isn't needed. Even with crappy RoHS tin solder. If you're getting significant-enough oxidation that interferes with rework with the product fresh out of the oven, or even a day or two later, you're doing something extremely wrong. Check and make sure your production paste isn't contaminated.