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 Jan 12 14:43:54 EST 2000 | JAX
Doug, Jedec has this info. Here is a few for you to use. LENGTH, L+LEADS, WIDTH, W+LEADS, PITCH, AVG. HEIGHT. 1. CQFP100AC: 17.28,22.35,17.28,22.35,.635,4.92 2. CQFP100AF: 32.52,37.59,32.52,37.59,1.27,4.92 3. PQFP100AD: 19.05,22.35,19.05,22.35,.
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 15 05:19:14 EDT 2001 | hardy boy
Hi, I have a fine pitch QFP (TQFP100) and after reflow soldering, i got less solder ( not enough fillet) on the toe area but have good fillet at the heel. Does this mean that I have a weak solder joint or is my process not too good ? What is importa
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
