I recently started at a new company. They have a variety of bare PCB's and most have aprox. 20 variations. Maybe about 1/3 of each board on average are non-populated locations. They buy one stencil for each PCB but then use scotch tape to block off most of the unused apertures. They think if they don't, they get bridging on non-populated QFP's. It makes inspection of no-pops easier and they think it makes the board look better. Also sometimes a board will get changed after assembly and it is easier to add a part if they is no solder on the pads. I agree with the last one. Although I want to get things set up so that product will be out the door so fast the engineers won't have time to make such changes.
Does anyone have any comments. We are getting a new machine with lots more feeders and will be able to dedicate almost all parts. Taping the stencil will be the biggest amount of time for changeovers.