Data Sheet
Table Of Contents
- 1 Design guidelines
- 2 Ordering Information
- 3 Pinout and Terminal Descriptions
- 4 Packaging
- 5 Power control
- 6 Interfaces
- 7 Block diagram
- 8 Example schematics
- 9 802.11 Radio
- 10 Firmware
- 11 Host interfaces
- 12 Electrical characteristics
- 13 RF Characteristics
- 14 Physical dimensions
- 15 Layout guidelines
- 16 Soldering recommendations
- 17 Certifications
- 18 Qualified Antenna Types for WF121-E
Silicon Labs
Page 39 of 45
16 Soldering recommendations
WF121 is compatible with industrial standard reflow profile for Pb-free solders. The reflow profile used is
dependent on the thermal mass of the entire populated PCB, heat transfer efficiency of the oven and
particular type of solder paste used. Consult the datasheet of particular solder paste for profile configurations.
The following recommendations apply for soldering the module to ensure reliable solder joint and operation of
the module after soldering. Since the profile used is process and layout dependent, the optimum profile should
be studied case by case. Thus following recommendation should be taken as a starting point guide.
• Refer to technical documentations of particular solder paste for profile configurations
• Avoid using more than one flow.
• Reliability of the solder joint and self-alignment of the component are dependent on the solder
volume. Minimum of 150µm stencil thickness is recommended.
• Aperture size of the stencil should be 1:1 with the pad size.
• A low residue, “no clean” solder paste should be used due to low mounted height of the component.
• If the vias used on the application board have a diameter larger than 0.3mm, it is recommended to
mask the via holes at the module side to prevent solder wicking through the via holes. Solders have a
habit of filling holes and leaving voids in the thermal pad solder junction, as well as forming solder
balls on the other side of the application board which can in some cases be problematic.