SI4720-B20 Datasheet, PDF (46/48 Pages) Silicon Laboratories – BROADCAST FM RADIO TRANSCEIVER FOR PORTABLE APPLICATIONS

Si4720/21-B20
Table 23. PCB Land Pattern Dimensions
Symbol
D
D2
e
E
E2
f
GD
Millimeters
Min
Max
2.71 REF
1.60
1.80
0.50 BSC
2.71 REF
1.60
1.80
2.53 BSC
2.10
—
Symbol
GE
W
X
Y
ZE
ZD
Millimeters
Min
Max
2.10
—
—
0.34
—
0.28
0.61 REF
—
3.31
—
3.31
Notes: General
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and tolerancing is per the ANSI Y14.5M-1994 specification.
3. This land pattern design is based on IPC-SM-782 guidelines.
4. All dimensions shown are at Maximum Material Condition (MMC). Least Material
Condition (LMC) is calculated based on a fabrication allowance of 0.05 mm.
Note: Solder Mask Design
1. All metal pads are to be non-solder-mask-defined (NSMD). Clearance between the
solder mask and the metal pad is to be 60 mm minimum, all the way around the pad.
Notes: Stencil Design
1. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should
be used to assure good solder paste release.
2. The stencil thickness should be 0.125 mm (5 mils).
3. The ratio of stencil aperture to land pad size should be 1:1 for the perimeter pads.
4. A 1.45 x 1.45 mm square aperture should be used for the center pad. This provides
approximately 70% solder paste coverage on the pad, which is optimum to assure
correct component standoff.
Notes: Card Assembly
1. A No-Clean, Type-3 solder paste is recommended.
2. The recommended card reflow profile is per the JEDEC/IPC J-STD-020C
specification for small body components.
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