0.635 mm Pitch SSOP
- Pin pitch (e): 0.635 mm
- Lead width (b): 0.18 – 0.30 mm
- Recommended pad width: ~0.25 mm
- Recommended pad length: 1.30 – 1.50 mm
0.65 mm Pitch SSOP
- Pin pitch (e): 0.65 mm
- Lead width (b): 0.22 – 0.38 mm
- Recommended pad width: 0.30 mm (nominal)
- Recommended pad length: 1.40 – 1.60 mm
- Pad-to-pad spacing: 0.35 mm (center-to-center 0.65 mm minus pad width 0.30 mm)
SSOP-16 (0.635 mm pitch) Stop Mask Guidelines
- Copper pad width: ~0.25 mm (typical)
- Solder mask expansion: +0.05 – 0.07 mm per side
- Mask opening width: ~0.35 – 0.39 mm
- Pad-to-pad spacing (center-to-center): 0.635 mm
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Mask dam (between pads):
- 0.635 – (0.25 + 0.25) – (2 × expansion 0.05–0.07)
- ≈ 0.08 – 0.10 mm left as mask dam
- Fabrication note: Some fabs require ≥0.10 mm mask dam, so if your fab’s capability is 0.10 mm, you are right at the limit.