DocID023971 Rev 3

3/13

AN4211

Printing and stencil parameters

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Printing and stencil parameters

The soldering paste thickness and pattern are important for the proper microphone

soldering process. Here below, some recommendations to be followed are listed:



Stainless steel stencils are recommended



Stencil thickness of 75 - 100 µm (2.95 - 3.94 mils) is recommended for screen printing



The final soldering paste thickness should allow proper cleaning of flux residuals and

clearance between the sensor package and PCB



Stencil aperture should have a rectangular shape



The openings of the stencil for the signal pads should be between 70 - 90 % of the PCB

pad



Optionally, for better solder paste release, the aperture walls should be trapezoidal and

the corners rounded



The fine IC leads pitch requires accurate alignment of the stencil to the PCB. The

stencil and printed circuit assembly should be aligned to within 25 µm (1 mil) prior to

application of the solder paste