QFN window arithmetic: make the assumptions visibleIllustrative geometry only. Coverage does not predict void fraction, standoff or thermal resistance.QFN window arithmetic: make the assumptions visible4 × 4 mm exposed pad3 × 3 windows; 0.30 mm webs0.20 mm margin on every edgeEach window: 1 × 1 mmNominal coverage: 56.25%At 100 µm foil: 0.90 mm³ geometric volumeVias and rounded corners are not modeled.Illustrative geometry only. Coverage does not predict void fraction, standoff or thermal resistance.