Circuit Board Voids

Circuit Board Voids are cavities or air pockets inside the solder joint formed by gases that are released during reflow or by flux residues that fail to escape from the solder before it solidifies.

Process and design-related causes of circuit board voids:

• Improper solder volume due to improper land design
• Improper solder volume due to blocked stencil aperture
• Improper solder volume due to improper stencil design
• Paste viscosity too low
• Paste metal content too low
• Bad or expired solder paste
• Ambient humidity too high for solder paste work envelope

Reflow-related causes of circuit board voids:

• Preheat too aggressive for flux – adjust to manufacturer’s recommendations
• Improper profile for solder paste