Optimizing Inner Layer Copper Aspect Ratios to Prevent Lamination Trace Swim
Prevent inner layer trace swim by maintaining conductor aspect ratios below zero point five zero and pairing heavy copper with high glass fill prepregs.
Organo Metallic Oxide Treatment
Adhesion Promotion
Chemical processes that apply a thin, organo-metallic coating to inner-layer copper surfaces increase the mechanical bond between the copper and the curing prepreg resin. This organo metallic oxide treatment replaces the traditional black or brown oxide processes by offering a more uniform and less brittle surface profile. This treatment provides high thermal stability and prevents the delamination of multilayer boards during lead-free assembly.
Chemical Mechanism
Curing prepreg resin requires a high-surface-area copper finish to ensure strong physical interlocking during the lamination press run. The organo metallic oxide treatment chemically modifies the copper surface by depositing a micro-crystalline layer of copper oxide and organic molecules. This coating is more resistant to the acidic chemicals used in subsequent plating and etching steps, preventing the pink ring defect around drilled holes.
When a board suffers from the pink ring defect, it indicates that the adhesion treatment has dissolved, leaving a gap where moisture and plating solutions can enter. This chemical process is carefully controlled using automated plating lines to ensure consistent coating thickness and complete coverage across the entire panel.
Substrate Reliability
Enhanced adhesion protects the board from the thermal shock of wave soldering and multiple reflow cycles. This treatment is a preferred choice for high-reliability boards in medical and industrial applications where mechanical failure is not tolerated. By providing a stable, high-adhesion surface, this chemical treatment ensures the long-term integrity of the multilayer board.