Board requirements, coating

The first commercial boards usiag electroless plating for connection between the sides were made by Motorola ia 1953 (41). An unclad plastic board was coated with electroless silver, a reverse resist appHed, and copper electroplated to the required circuit thickness. The resist and excess silver were removed. This semi-additive process is stiU used, with copper replacing the silver. 

For board grades, the coat weight depends on the requirements of the final product and on the quality of the base board. Coverage, brightness and smoothness are the main properties that are improved by the coating. Depending on the required coat weight two or three coat layers are applied. 

Almost any substrate that will be powder coated, whether it is metal, medium-density fiberboard (MDF), or some other material, requires some kind of surface freafmenf. Surface preparafion (prefreafmenf) of wood and more specifically, MDF preparation consist of sanding, removal of confami-nanfs, and board condifioning. MDF boards fhaf will be coafed by UV curable powders should have a moisture content of 49%. If is also a common practice fo preheaf MDF boards prior to application of fhe UV powder. Mefal surfaces are always cleaned by washing and usually freated by a phosphafe primer. Conductive plastics are washed and dried and then coated without any further treatment. Nonconductive plastics are made conductive by applying a primer coat or treated by plasma or flame. ... 

Fiber cement siding, which is produced from a blend of cement, sand, and cellulose fibers. This blend is extruded into board, which is then cured by pressurized steam. Unlike composites, fiber cement siding does not require surface treatment. Normally, a primer is applied first, followed by another coating to achieve the desired color. 

For laboratory tests use may be made of a small jacketed metal oven containing heavy mineral oil and coated with asbestos board it is heated by gas and serves to bake loaves of about 150-200 grams prepared by doughing 1 kilo of flour with the required amount of water (about 500 c.c.), 1% of sodium chloride and 20 grams of beer (or pressed) yeast being added and the whole left to rise for 2 hours in an oven at 30-330 C. 

In the L79 design, both the gas flow fields and electrodes are made from single sided copper clad circuit board. Copper clad circuit board comes in a variety of sizes and is either clad with copper on one side only, or both sides. Boards also differ in the type of base material they are made of. This fuel cell requires the FR-4 glass epoxy resin base, clad with copper on one side only. We used a 1 ounce, which is coated with copper to a thickness of. 0014". 

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