Data Sheet

Bluegiga – A Silicon Labs Company 38
Soldering recommendations
Bluegiga Bluetooth Smart Ready module BT121 is compatible with the industrial standard reflow profile for
Pb-free solders. The reflow profile to be used depends on the thermal mass of the entire populated application
PCB, heat transfer efficiency of the oven and on the particular type of solder paste used. Consult the
datasheet of the particular solder paste used for more detailed information regarding profile configurations.
The following recommendations for soldering the module are to ensure reliable solder joints and operation of
the module after soldering. Since the soldering profile used is process and layout dependent, the optimum
profile should be studied and decided case by case.
The following recommendation should be taken only as a starting point and should be adjusted according to
more detailed instructions of the solder paste and soldering equipment manufacturers.
 Check the recommended soldering profile configuration from the solder paste manufacturers
documentation.
 Avoid using more than one flow.
 Reliability of the solder joints and self-alignment of the component are dependent on the solder
volume. A minimum stencil thickness of 150 m 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 the low mounted height of the module.
 If the vias used on the application board have a diameter larger than 0.3 mm, 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. These phenomena can in some cases cause
problems.