Electronics Forum | Wed Aug 07 17:20:17 EDT 2019 | orbitcoms
The aperture over the pads is set to 95% coverage of the pad. The stencil is 0.12 mm thick.
Electronics Forum | Wed Aug 07 18:32:22 EDT 2019 | orbitcoms
How would I measure/observe coplanarity issues ?
Electronics Forum | Wed Aug 07 01:41:27 EDT 2019 | orbitcoms
Hi I am having trouble getting solder bridges on TQFP-100 (0.5mm pitch) components. The boards are pasted on semi-auto printer using laser-cut 0.12mm stencil and SN63 NC257-2 T4 paste. The components are placed using Samsung CP40LV and tghen reflow
Electronics Forum | Wed Aug 07 12:41:58 EDT 2019 | slthomas
Are the apertures on the stencil reduced in width or 1:1 with the pads? It depends on the pad width and foil thickness but we usually reduce aperture width for any part that results in an aperture wall spacing of less than 8.5 mils.
Electronics Forum | Wed Aug 07 18:00:56 EDT 2019 | orbitcoms
I am doing another run today. I'll check how central the machine is placing the components onto the pads. I wonder if the part is off slightly and smudges past across the pins? What about if the part is being placed too deep into the paste?
Electronics Forum | Wed Aug 07 22:40:03 EDT 2019 | slthomas
Most placement machines will do a check for that prior to placement and reject the parts. I just wondered if that was something that you'd experienced while also seeing the bridges.
Electronics Forum | Thu Aug 08 22:22:05 EDT 2019 | sssamw
Did you solved this issue? I would recommend you track online station by station, until you detected the solder bridge, so you can narrow down the analysis scope and focus on potential causes.
Electronics Forum | Wed Aug 07 17:55:33 EDT 2019 | slthomas
You should be well within area and aspect ration guidelines with that. Are you printing and placing close to center on the pads? Sometimes operators will "bump" the parts to center them on the pads if they're not placed correctly, and if they've bee
Electronics Forum | Thu Aug 08 13:05:45 EDT 2019 | horchak
What is your pad width? What is lead width? Is the part gang masked, or has masking between the pads? Pads plated or HASL, if HASL how thick? What is board thickness and size? Does it need to be fixtured for support thru out the process. Semi auto sc
Electronics Forum | Thu Aug 08 22:41:30 EDT 2019 | orbitcoms
The pick n place height for component was set to 1.4mm but I had not allowed for pin thickness. I added this (total height now 1.6mm) and I get very few solder bridges now. I might try 1.7 and see if it makes any further differnce
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