QSMP

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