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. Traditional Sn/Pb soldering processes have a peak reflow 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 optimal profile must take a few factors into account:
• Solder paste flux used
• Size of the board
• Density of the components on the board
• Ratio of large and small, lighter components (the mixture)
Chapter 3: Mechanical Design Considerations
UG1091 (v1.0) April 20, 2021
Carrier Card Design for Kria SOM
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