Appendix A. SMT Assembly Application Note
1.0 Solder Pad, Mask and Metal Stencil Aperture
Metal Stencil For
Solder Paste
Printing
1.2 Recommended Metal Solder Stencil Aperture
It is recommended that a 0.11 mm (0.004 inches) thick
stencil be used for solder paste printing. Aperture open-
ing for shield pad is 0.4mm x 0.4mm and 0.2mm x 0.4mm
(as per land pattern). This is to ensure adequate printed
solder paste volume and no shorting.
Stencil
Aperture
Land
Pattern
Solder
Mask
PCBA
Aperture
Opening
0.11
1.6
1.7
Unit: mm
Figure A1. Stencil and PCBA
Figure A3. Solder Stencil Aperture
1.1 Recommended Land Pattern
CL
0.4
0.3
1.3 Adjacent Land Keepout and Solder Mask Areas
Adjacent land keep-out is the maximum space occupied
by the unit relative to the land pattern. There should be no
other SMD components within this area.
The minimum solder resist strip width required to avoid
solder bridging adjacent pads is 0.2 mm.
Note: Wet/Liquid Photo-Imageable solder resist/mask is
recommended.
0.45
0.9
2.6
0.4
Mounting
Center
2.7
0.2
Figure A2. Recommended Land Pattern
0.4
Unit: mm
0.2 MIN.
Figure A4. Adjacent Land Keepout and Solder Mask Areas
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