Homemade multilayer PCB and surface finishing

[hv222]

Hi,

Is someone here with experience with 4+ layer PCB? I making 2-layer PCB boards for over one year with very good results. I'm using electroless copper proces from DOW Electronic Materials and galvanic copper plating solutions from Schloetter. Basically I need add only copper oxide, lamination and desmear processes. What copper oxidation process is better for home production - brown (organic) or black(inorganic) or it is not necessary and can be replaced by mechanical process (ex. sand paper)? What cheap press can be used for lamination process? I thing about buy something like this: https://www.amazon.com/Promo-Heat-Sublimation-Transfer-Machine/dp/B005Y2C8XG. Typically desmear process is most important in multilayer process due to providing best copper to copper contact while plating. Is it possible to replace it by some mechanical process (plasma desmear is to expensive) if not, maybe is it possible to make chemical process less complicated? Typically there are 3 chemical baths, 1st  - epoxy softener 2nd - alkaline permanganate solution and 3rd - neutralization solution.
Currently I'm manually add solder over all pads and control it height with desoldering wire or using galvanic gold (directly over copper). Both ways need lot of time. What other processes can be used in home? I heard about Sterling Silver from Mac Dermid, but it's hard to order it in small quantity and some same situation with TINPOSIT LT34. I looking for some flat surface finishing for BGA components. ENIG is too much complicated (requires about 22 baths).