1. Many board shops will do a final clean operation (typically a saponifying
heated detergent spray rinse, tap water and final DI water rinse), just prior
to the boards being packaged and shipped to the customer. This is done to
remove any contaminants that can arise from handling when the panels are
routed into boards,   electrically tested, etc.This is primarily done to make
sure the boards are clean when they leave the board shop, look good and will
meet ionic cleanliness requirements if a random sample is selected. You might
want to contact your board supplier(s) to see if the do this final clean
step. If so, you probably would not need a pre clean prior to assembling the
boards.

2. There are some assemblers that do use dish washer type machines to clean
fully assembled boards. In fact, ECD in Oregon makes a dish washer type
machine specifically for cleaning assembled boards. The down sides are that
the machines will only hold a few boards (no good for any kind of volume
production), the cycle time is quite long (up to 1 hour - similar to a dish
washer) and the assembled board is subjected to long exposure in a very high
temperature/high humidity environment. I would think the solvent
cleaning/vapor degreasing you are now using would be a better approach,
especially with the RMA solder pastes you are now using.

Hope this helps.

Larry Fisher

Allen Woods & Associates