Deon Response: Hello Will,
Yes, you can reflow a double sided board using 63/37 solder paste on both sides. There are some limitations as far as the mass of the components to reflow the second time. If you have doubts or are concerned that a component will fall off during this secondary reflow, use the following formula: Take the weight of the suspect component in grams and divide it by the total lead to pad area mating surface. If this equals to less than 30gms/sq.in. the surface tension should keep this component in tact during reflow.
As far as your reflow oven is concerned, I would have some board supports made at a machine shop. I would make these out of aluminum or titanium. These should be light and as small as possible this way they will not act as a heat sink during reflow. I have had some made in the past. These were long rods with a long slot where the PCB can be inserted in or on. Nothing too complicated but functional.
Hope this helps.
Deon Nungaray SMT Mfg Process Engineer GMI USA
reply »