While looking for information on paint on solder mask materials I can on an article with solder masks made out of heat resistant material to assist in the reworking of boards with BGA chips. Now BGA chips are my worst nightmare. I never know if I got a good solder job under the chip. I notice that companies use high $$ x-ray machines to look for dogbone solder balls on the bottoms of their chips. That is clearly out of the league of SparkFanatics.
The URL below is a pdf sales pitch about the solder mask repair product. My thought is, however, why not use the rework mask for the inital chip installation. A movie shows the tech attaching the mask to the board, taping around the chip to keep gunk off the rest of the circuit, mushing solder paste around with a squigee, removing the shielding tape, and poping that BGA right down on the PCB.
I like to make my own laser printer homebrew PCB before I spend the big bucks and time to have a board built in China. When I have the bugs worked out, then I get boards made that I can show off. Most of my first boards go into the recycle pile to be stripped of parts and the board pitched. ( My boards are too small to make into coaster as SparkFun does. ;=)) )
I could imagine using “semi-permanent solder masks” as my prototype standard for my experimental boards. Being able to use BGA chips without having nighmares would be a nice change.
The bad news is that BEST Inc. only sells the masks $70 for 10 masks of one size and type. I would really like to be able to buy two of one type and one of another. They are only listing BGA repair masks. I would see them for 62, 64, and 128 pin chips. Paste on the mask, mush in solder paste, place the parts on top of the solder paste, and pop into your hot air oven until done. I just love the smell of fresh baked PCB in the evening!