Clean copper clad laminate with an automatic scrubbing machine, scrub manually with acid pumice slurry, or chemically clean. Blow dry with clean, oil free air. Several other cleaning methods work acceptably such as jet pumice scrubbers, Scotch-Brite tm , aluminum oxide spray, pumice brushing, and chemical cleaning. Consult your technical representative for additional assistance. Only use pressures recommended by the laminator manufacturer to assure that the equipment will not be damaged.
Automatic lamination is also acceptable.
Allow the panels to cool for fifteen minutes. Panels should never be stacked on top of each other. This will cause trapped dirt particles to imprint the resist from one board to the next and cause the resist to flow into the holes affecting tenting. Stacking also traps heat and interferes with resist performance during exposure or development. Leave polyester protective sheet on boards to protect photoresist until exposure has been completed and the panels are ready for development.