Copper in circuit boards carry the electrical current and signals. The thickness of copper layers in PCB's are typically H oz and 1 oz. Copper thickness is expressed in weight with 1 oz equal to .0014" or 35um nominal thickness. For high current, high amperage applications like power supplies, thicker copper is required. PCB's with >2 oz finished copper are considered heavy copper.
Manufacturing heavy copper boards is not a trivial task. To start, you must have material stock or reliable suppliers for the thicker foils. Design rules must be in place to ensure adequate spacing for etching and dielectric separation. Prepregs must be adjusted to use appropriate glass styles and resin content. Lamination conditions require customization. Soldermask process must be adjusted to provide adequate coverage. Special testing procedures and conditions may be required on the final product.
External copper or Outerlayers are plated up during the plated through hole process, but the etching is for the starting foil only (for pattern plating process). Therefore, the minimum line widths and spacing for inners are not the same as outers. Please see tables below for details and contact us if any questions.
Sunshine Global has experience with this type of product to 20 layers or more (see example on this page). We have UL approval up to 6 oz for internal and external copper and we can support this type of product for QTA as well.