Substrate Defect Attributable Scrap Clawback Formulas in High Density Interconnect Quoting
HDI scrap clawback formulas isolate raw substrate flaws from process loss to recoup unrecovered value-add costs across sequential lamination steps.
Microvia Plating Dropouts
Discontinuity Event
Incomplete copper coverage within a laser drilled blind via occurs when the electrolytic or electroless process fails to coat the entire hole wall. While microvia plating dropouts typically appear as small voids in the copper layer, they can lead to total electrical open circuits. The risk increases as the aspect ratio of the hole becomes more aggressive.
Deposition Failure
Air bubbles trapped at the base of a blind hole often prevent the plating solution from reaching the target pad. These microvia plating dropouts happen most frequently during the initial strike when chemistry must displace air in a very small volume. Without a continuous metal path, the interconnect cannot support the current density required for signal transmission.
Inspection Method
High magnification visual inspection and electrical continuity testing identify these gaps in the vertical interconnect structure. Because microvia plating dropouts often hide beneath the top surface of the copper, x-ray or cross sectioning remains the most reliable way to confirm the integrity of the wall. A single dropout on a high density interconnect layer renders the entire circuit board unusable because it compromises the reliability of the high speed signal path.
Technicians look for patterns in the deposition that suggest poor fluid agitation or improper desmear before the plating step.