1) Run your boards through a reflow oven, and then use a wiper/scraper system in the peak temp section to rub the parts off the board and onto a metal screen conveyor. The wiper is a silicone rubber (or woven metal wool) squee-gee and reciprocates with each board. You can even have an array of these squee-gees to work the boards in succession (first line does big stuff, and the subsequent lines knock off progressively smaller components. I'll post a hand drawing of this later.
2) Use an air knife to:
- A cause preheating of downstream boards
- Melt the solder and blow components off up-close board.
So in other words, you feed hot compressed air into an air knife, and use this hot air to knock components off (and into a catch bin or metal screen conveyor). You'd likely also have a preheat section that works in conjunction with spent hot air, but that hot air can do a lot of preheating by itself. mainly preheat lamps or elements just help to smooth out preheat/post heat temp gradients.
3) Use a centrifuge with convection heating. The boards go in with a metal mesh catch bag that fits over the boards. You circulate air that heats up progressively while you gently spool up the centrifuge. Each board/bag fits into a locking carrier. The carriers themselves latch into slots provided every n/360 degrees, where n is the number of boards to desolder per batch (I'm thinking n=10 to 20 for now). The centrifuge is about 3 foot in diameter, and spins up to such a speed as to give a maximum g acceleration of between 5-100 (g's) (or in other words 50-1000 m/s^2).
4) Use a reflow oven again like in #1, but this time you use a spinning sweeper, a lot like the sweepers used to clear snow on sidewalks. Except this booger uses music wire or other hardened steel wires instead of fiberglass/thermoplastic, and the diameter is smaller. The sweeper sweeps the components off into a bin or metal screen conveyor.
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