On a HASL board that has poor wetting on the pad, consider looking further downstream in the process than your assembly shop. For instance, take a look at the bare boards. Look for solder mask bleed onto the pads. This will show-up on the outside edges of the pads. Don't expect the bleeding to be the same color as the solder mask. Expect to see incomplete solder coverage on the pads after running the board over the wave solder machine.
Q1: 6 thou stencil acceptable? A1: Sure that's fine
Q2: Issues with Kester 256 no clean? A2: None. Although if you're leaning towards chasing solder paste issues, handling and storage of the paste might be a more fruitful direction to head rather than Kester.
Q3: Can thin plating on HASL boards cause dewetting? A3: Probably not, but other fabrication issues could. Think of thin HASL as a symptom. What do you mean by "thin"?
Q4: Is it standard to run mole profiles after every changeover to different products during the production day? Q4: Sounds reasonable to expect something like that. While not "standard", it IS good practice. Since not all products have the same profile, checking that the oven is at temperature before running product seems like a good thing.
reply »