Table 15: Board to Board Connector Recommended Stencil Design
Aperture Shape Pitch Diameter Stencil Thickness
Round 25 mils and 37.8 mils 14 mils 5 mils
Figure 9: Board to Board Connector Recommended Stencil Design
Recommended Pb-free Reflow Soldering
Profile
Xilinx does not support soldering SnAgCu BGA connectors with Sn/Pb solder paste during the
soldering process. Tradional Sn/Pb soldering processes have a peak reow temperature of
220°C. At this temperature range, the SnAgCu BGA solder balls cannot properly melt and wet to
the soldering surfaces. As a result, reliability and assembly yields can be compromised.
The opmal prole must take a few factors into account:
• Solder paste ux used
• Size of the board
• Density of the components on the board
• Rao of large and small, lighter components (the mixture)
Chapter 3: Mechanical Design Considerations
UG1091 (v1.0) April 20, 2021 www.xilinx.com
Carrier Card Design for Kria SOM 47
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