Hi, I am working on a PCB art project where I have a portion of the solder mask cut out as a graphic element (because the exposed silver traces look cool). I have some traces going through this area, and I’m wondering what kind of clearance I should give them to avoid shorts during the HASL (hot air solder leveling) fabrication process.
Thanks!
Does your board house have any suggestions?
First guess is that SMD pads with a 0.5mm pitch should be able to get through HASL even though HASL is not recommended for SMT IC’s because of nu-evenness.
How many units are you planning to make?
If it’s just a handful, then I would not bother with this at all, and just ad a bit of flux and drag a soldering iron over it if needed.
HASL is really uneven, this going to be very noticeable if you have larger areas. If you want silver color, I’d consider silver plating or chemically plated tin (can be done at home if your fab does not offer it: https://youtu.be/4dZ2LKe7660?t=962) But durability / oxidation of chemical tin/silver is likely worse than HASL.
For clearances with HASL, the normal trace minimum of your fab is going to be fine.
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