Si7050/1/3/4/5-A20

Rev. 1.14

21

10. PCB Land Pattern and Solder Mask Design

Figure 4. Si705x PCB Land Pattern

Table 14. PCB Land Pattern Dimensions

Symbol

mm

C1

2.90

E1.00

P1

1.60

P2

2.50

X1

0.45

Y1

0.85

Notes:

General

1.

All dimensions shown are at Maximum Material Condition (MMC). Least Material

Condition (LMC) is calculated based on a Fabrication Allowance of 0.05 mm.

2.

This Land Pattern Design is based on the IPC-7351 guidelines.

Solder Mask Design

3.

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.

Stencil Design

4.

A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls

should be used to assure good solder paste release.

5.

The stencil thickness should be 0.125 mm (5 mils).

6.

The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pins.

7.

A 2x1 array of 1.00 mm square openings on 1.30 mm pitch should be used for the

center ground pad to achieve a target solder coverage of 50%.

Card Assembly

8.

The recommended card reflow profile is per the JEDEC/IPC J-STD-020

specification for Small Body Components.