Silicon Laboratories SI4734/35-B20 manual Si4734/35-B20, PCB Land Pattern Dimensions

Si4734/35-B20

Table 17. PCB Land Pattern Dimensions

Symbol	Millimeters
	Min	Max
D	2.71	REF
D2	1.60	1.80
e	0.50	BSC
E	2.71 REF
E2	1.60	1.80
f	2.53	BSC
GD	2.10	—

Symbol	Millimeters
	Min	Max
GE	2.10	—
W	—	0.34
X	—	0.28
Y	0.61	REF
ZE	—	3.31
ZD	—	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.

Notes: 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 µm 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 0.125mm (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 stand-off.

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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