An arboron sheet is made from a composite laminate of melamine-faced kraft paper that has been impregnated with phenolic thermosetting resins and then compressed through high pressure and heat. Arboron sheet offers an exceptional anti-static dissipative material that has excellent dimensional stability and superior machining capabilities. Arboron sheet is widely used as substrate for printed circuit broads because of the assurance that their components will be protected from heat and static discharge. Increased productivity and output is also achieved from reduced soldering defects.
Materials for used for printed circuit boards
The substrate that is typically used in making printed circuit boards is fiberglass that is reinforced with epoxy resin with copper foil bonded to one or both sides. There are also circuit boards that are made from paper reinforced phenolic resin with a bonded copper foil. This type of substrate is less expensive and it is widely used for household electrical devices. Another option is arboron sheet that is not made from polyester resins or reinforced with glass filament; it is made from a high density compressed paper based phenolic impregnated sheet material with a melamine surface.
The printed circuits are made from copper that are either plated or etched away on the surface of the substrate according to the pattern desired. The copper circuits are coated with layer of tin lead in order to prevent oxidation. The contact fingers are also coated with tin lead after which it is coated with nickel and then gold to achieve excellent conductivity.
The manufacturing process for circuit boards
It is important to ensure that there is a clean environment in the processing and assembly of printed circuit boards. In the process of making a substrate, the material which is either fiberglass or high density compressed paper passes through rollers so that the desired thickness for the finished substrate will be achieved. It is then impregnated with epoxy resin through the process of dipping or spraying. The substrate is semi-cured in an oven and excess resins are removed. After curing, the substrate is cut into large panels that are stacked in layers. Alternating with the layers is the adhesive-backed copper foil. The stacks are placed in a press where they are treated with pressure at 1500 psi and temperature at about 170oC for an hour to fully cure the resin and tightly bond the copper foil to the surface of the substrate.
Several panels of the fully cured substrate with sizes that are large enough for a circuit board will be stacked one on top of the other before they are placed into a CNC machine for holes to be drilled according a specific pattern. The inside surfaces of the holes will be designed to provide a conductive circuit from one side of the board to the other and are plated with copper. The printed circuit pattern will then be created through an additive or subtractive process. In the additive process, copper is plated or added to the surface of the substrate in a desired pattern while in the subtractive process, the entire surface is plated and then the areas that are not part of the design are etched.