QS8M
Soldering Recommendations
Ka-Ro QSCOM modules are compatible with industrial
standard reflow profile for Pb-free solders. Ka-Ro will give
following recommendations 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 recommendations should be taken as a
starting point guide.
•
Refer to technical documentations of particular
solder paste for reflow profile configurations
•
Avoid using more than one flow.
•
A 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.
Recommended stencil design
Aperture size of the stencil is 1:1 with the pad size. Four
1.7mm diameter bumps are used for each of the 4.3mm
square GND pads sections giving a 50% solder paste
padding. The lower component settling with this ensures
that the pads at the edge are always soldered even at
vertical misalignment by distortion or warping.
Thermal Considerations
The QSCOM module consume more than 1 W of DC power.
In any application where high ambient temperatures for
more than a few seconds can occur, it is important that a
sufficient cooling surface is provided to dissipate the heat.
The thermal pad at the bottom of the module must be
connected to the application board ground planes by
soldering. The application board should provide a number of
vias under and around the pad to conduct the produced
heat to the board ground planes, and preferably to a copper
surface on the other side of the board in order to conduct
and spread the heat. The module internal thermal resistance
should in most cases be negligible compared to the thermal
resistance from the module into air, and common equations
for surface area required for cooling can be used to estimate
the temperature rise of the module. Only copper planes on
the circuit board surfaces with a solid thermal connection to
the module ground pad will dissipate heat. For an
application with high load the maximum allowed ambient
temperature should be reduced due to inherent heating of
the module, especially with small fully plastic enclosed
applications where heat transfer to ambient air is low due to
low thermal conductivity of plastic. The module measured
on the evaluation board exhibits a temperature rise of about
20°C above ambient temperature. An insufficiently cooled
module will rapidly heat beyond operating range in ambient
room temperature.
Ka-Ro electronics GmbH - Pascalstr. 22, D-52076 Aachen, Germany - Tel.: +49 2408 1402-0 (FAX -10)
www.karo-electronics.de