Composite
FR-4 laminate
Glass-reinforced epoxy, panelised and depanelised. Scrap is panel yield and the boards that fail at test after every component on them has already been paid for.
Typical scrap rate
2.5%
Yield multiplier
1.0256x
Effect at 1,000 units
At 1,000 units it adds $0.11 to a $14.06 landed unit. It is the latest-occurring scrap of the six: it is lost after assembly, not before.
Notes
Board scrap is the most expensive kind on this list because of when it happens. A panel that fails at electrical test has already been drilled, plated, populated with every component on the bill of materials, reflowed and inspected.
Yield at test is therefore a component-cost problem wearing a material-cost label. Improving it moves a larger number than the 2.5% suggests, and worsening it moves that number the other way just as fast.