Can HASL finish be used for castellated pads?

I am designing a PCB that uses castellated edges to connect to the parent board. I would like to use hot air solder leveling finish to save on costs for prototyping, but I am concerned that the non-planar surfaces of the module may pose assembly issues. Is it common at all to use HASL for castellated boards, or do I need Electroless Nickel Immersion Gold to ensure successful assembly?

PCB Assembly, PCB Design
December 1, 2023

Yes. Hot air solder leveling works fine for plating through holes, even large holes, I see no reason for it not to work with castelation. It does somewhat bind you to a solder chemistry, (lead or lead-free) and also has a shorter shelf-life than ENIG.

Oliver Smith

Oliver is an experienced electronics engineer skilled in PCB design, analog circuits, embedded systems, and prototyping. His deep knowledge spans schematic capture, firmware coding, simulation, layout, testing, and troubleshooting. Oliver excels at taking projects from concept to mass production using his electrical design talents and mechanical aptitude.

Oliver Smith

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