Ok, so I've been reading the manual of the weller WAM3000 very carefully, and here is my
guess at how it works. Also, nailed down some parameters I think would be reasonable to aim for. See attached for the diagram taken from the weller manual here:
http://www.egmont.com.pl/cooper/instrukcje/OI_WAM3000_GB.pdfThe weller machine supports a 300x300x55mm board. I'm guessing the air space cross section in the chamber is maybe 350x350mm ? It also supports a load of maximum 1kg. I have some medium sized steppers lying around from a different project which are rated at about ~3 Nm, so with a small sprocket and chain drive it should easily be able to lift 1kg+1kg platform. This seems like a pretty good target load.
The machine drawing appears to be to scale (all of the external dimension ratios match the machine specs). From this, I have the following very rough measurements:
Full chamber (including gated zone but not including fluid container): 360mm high, 350mm square
Gated location: 120mm from the top of the fluid container
Fluid container: 40mm high, 200mm square
First, you have three sensors. I'm going to assume these are thermocouples, given that the vapour is optically transparent and is extremely chemically inert. The right thermocouple should hopefully have a fast enough response time. (Maybe using those fairly recent 4x4 thermopiles or something could be interesting here. melexis is the company iirc?). Level 1 is closest to the heater at the bottom.
Here are the basic steps:
- Heat the vapour phase fluid until Level 1 reaches the defined preheat temperature
- Open the top door, put your populated board onto a mesh platform. Close the door and press go
- The board is lowered approximately to the level 2 sensor and the gate above the level 3 sensor is closed
- Heat is applied to the fluid until Level 3 reaches the defined finish temperature. The vapour will not rise that high unless the PCB is unable to absorb any more heat; this means that basically condensation has stopped and the solder should be fully reflowed
- Heat is reduced and external cooling fans are turned on. After level 2 drops below a defined temperature, the gate will be opened and the mesh platform will be lifted
- Enjoy your freshly soldered PCB!
PS while I'm not saying anyone should throw out your soldering irons, have you seen the price of the high end weller/pace/ersa/metcal gear? It makes the fluid look very cheap in comparison!
I think that an entire DIY vapour phase setup (with fluid) would cost less than one of my weller stations, and I have two of them!