Electronics > Projects, Designs, and Technical Stuff
Vapour phase Soldering
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tautech:

--- Quote from: Koen on December 06, 2015, 07:16:00 am ---Hello, I read the thread (but couldn't watch the videos) and couldn't find an answer to this question : in a homemade setup, Galden in a cooking pot for example, at which point is the PCB inserted ? Is it placed above the liquid Galden before heating up so the PCB will slowly warm up with the air ? Or is it dipped after the Galden turned to vapor and if so, is the PCB warmed up on the side before to avoid a thermal shock ? Thank you, Koen.

--- End quote ---
Pretty much as in this post:
https://www.eevblog.com/forum/projects/vapour-phase-soldering/msg596305/#msg596305
IconicPCB:
Some progress...

Tried domestic induction heating hot plate... did not work... not because the fluid did not get hot  but because the source of heat ( ferromagnetic stainless steel base ) but because the power density was too high.

Had to rethink the heating requirement and limit the input power density. So this time with same power input but from a rearranged source have brought the oven temperature up to 230C.

Need to do some mechanical tweaking in the hope of improving heating rate.

I found that LS230 evaporates at lower temp than the notional 230C. Vapor of some lighter fractions seems to evolve at temperatures around 100C. Do not know what they are but.. it is what it is.

A note of WARNING.. GALDEN decomposes into TOXIC compounds if heated above the typical range of operation be careful to manage power input into the boiler zone.

Next step will be to connect cooling fluid pipes and re run the experiment with the view to containing vapor with minimal losses.
uncle_bob:
Hi

All of the Galden fluids evaporate if you leave them in the open. The lower temperature stuff goes faster, but they all "vanish into air" if left out for a while. Best to put them in a tightly sealed bottle when not in use. Unfortunately the way we were using them that was not an option. Galden made a lot of money off of us on that project ..... We got somewhat lower loss rates off of the gear with chilled collars on them. In the end it was not clear if the compromises involved in that made sense or not.

Bob
Kjelt:
Bob do you mean to say that Galden evaporates also at roomtemperatures so you are forced to store it in a tight container after use?
uncle_bob:

--- Quote from: Kjelt on January 31, 2016, 04:39:22 pm ---Bob do you mean to say that Galden evaporates also at roomtemperatures so you are forced to store it in a tight container after use?

--- End quote ---

Hi

Yes, that's exactly correct. They do have a finite vapor pressure (even at room) so they head off into the air. Some of the stuff we used was lower temperature than the 230 so it was what we had the biggest problem with. How tight the container needs to be or if a simple float cover would work ... no idea. We went to bottles. One wise guy suggested a dropping a chunk of lard on top of the hot fluid ...

Bob
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