?

Please excuse my ignorance. Can someone tell me what a framed solder mask stencil is?? My suspicion is that it is a stencil that fits into some kind of contact frame like screen printing but I have not found an explanation that makes sense to me.? If I am correct then where does one find these contact frames and what are they called?

I asked because I was looking to order some smt boards from one of the Chinese board houses and for $7 I can get a frameless stencil but for $9.20 or so I can get one for a frame.? To me it would be ideal to have a frame since registration would be easier.

Also I have not figured out why all the board houses send a 380mm x 280mm even if the board it is for is small like 32mm x 22mm and that confuses me. Why isn't the stencil a few mm larger than the pc board but not gargantuan like it is?

Again what are the solder mask stencil frames called and where can I get one?? What is a stencil for frames compared to frameless?? Why are the board house stencils so huge compared to the actual size of the pc board the stencil is for?

Thank you.

Jim Pruitt