How can a printed circuit board manufacturer consistently produce board surface coplanality qualities that allow it to precipitate accurate, consistent amounts of solder paste on today's tightly distributed pads of design? The proper selection of materials is fundamental. Factors considered include the physical and electrical properties of the plate, its dimensional stability, impedance characteristics, Z-axis elongation, and uniformity and surface conditions. In fact, the uniformity and surface condition of the selected material may affect the final surface coplanarity.

For multilayer circuit boards mainly composed of ultra-close spacing boards, the choice of raw material layers should not affect the surface coplanarity. However, ultra-dense pitch products, typically characterized by very dense circuits, require the layer to have a smooth surface - often referred to as a "surface reinforced" material. This lamination is characterized by resin-rich prepregs that are backpasted on traditional 0.0007" (0.01778mm) copper foil. Therefore, for the PCB manufacturer, the final smooth surface of the board is completed in the same way as the surface reinforcement material produced by the layer manufacturer -; The copper foil is surrounded by a layer of resin-rich polyester film. When lines and gaps are below 0.004", the use of ultra-thin copper foil (0.00035") will help improve the pass rate.