Material Transport
Uncontrolled liquid movement is a process deviation where molten alloy escapes through gaps in protective fixtures or resist barriers during wave soldering. When solder bypass leakage occurs, the liquid metal makes unintended contact with areas that must remain free of solder. This contact can create short circuits or prevent the proper seating of mechanical housings.
Maintaining tight seals on selective soldering pallets prevents this escape of molten metal.
Liquid Behavior
High hydrostatic pressure within the solder wave forces the liquid metal through any available opening between the pallet and the board surface. This issue frequently arises when the board exhibits bow or twist that prevents the fixture from sitting flush against the solder mask. If the pressure exceeds the mechanical clamping force, the alloy sweeps past the sealing gaskets and spreads across the component side of the assembly.
Fabricators must select fixtures with flexible silicone seals that conform to the board contours even under high thermal loads. Regular inspection of the clamping hardware is necessary to prevent these leaks.
Circuit Damage
Unintended solder deposits on gold edge connectors render the board unusable unless expensive manual rework is performed. These deposits form hard metallic bonds that cannot be removed without damaging the underlying gold plating.
