Issue link: https://iconnect007.uberflip.com/i/1038326
40 PCB007 MAGAZINE I OCTOBER 2018 ables reliable transport in our systems and is supported by many con- trol devices. We control the solution level in the process area of the mod- ules, and the pressure of the solution flow from the pumps through the fluid devices to the pan- els. With this, we can as- sure the latest require- ments for transport ca- pabilities. Foley: Additionally, we implemented fine filtra- tion systems for all lines. This was required because GreenSource also wanted to process fine-line structures on these lines. To allow this, we have a fine filtration concept for all modules—not only active mod- ules—and on rinses and plating modules. Our horizontal acid copper system comes next in the process sequence. We have sever- al mixes of acid copper there, depending on needs (e.g., conformal plating, microvia fill, or through-hole fill). This adds up to three or four different acid coppers. Finally, we have the electroless nickel immersion gold (ENIG) line, which is currently a surface finishing line but will be electroless nickel electroless palla- dium immersion gold (ENEPIG). Holden: Why did GreenSource switch from di- rect metallization to electroless copper? Kuldip Johal: The direct metallization produc- tion line was designed for simpler double- sided products. However, for HDI products with wide product specifications as required by GreenSource, strong interconnect reliabili- ty and BMV coverage are needed—hence the palladium-based electroless copper process is preferred instead of the conductive polymer- based direct plating process. In the case of GreenSource, they planned for the highest flex- ibility with both capabilities in one manufac- turing location. Dreiza: They also needed throwing power in the finer, smaller vias. The electroless copper, called Printoganth T1, has that name because it has a throwing power of 1. This means the thickness of electroless copper that you get on the surface of the panel versus the bottom of the wedge of the blind microvia is almost the same. Holden: When the barcoder reads the barcode for jobs as they move through, what parame- ters are adjusted for differences in the process- es, conveyor speed, pressures, etc.? Foley: The recipe might change temperature, pressures, or dosing frequencies. Panel size is a factor in recipe tuning, too. Depending on copper thickness requirements and panel spec- ifications, the conveyor speed in the plater— as well as current densities and pulse forms— might change too. Our alternative oxide line was originally brought to market as an inner layer bonding system, but Alex is using it two- fold; he's using it for solder-mask adhesion and dry-film adhesion. He's roughening up the sur- face with the BondFilm, which provides better adhesion with the solder mask and dry film. Holden: Are they also using it for lamination adhesion promotion? Foley: That's correct. Figure 4: The Atotech Uniplate Cu at GreenSource Fabrication.