@DM_Ronin ah you see, QFP has fooled you into thinking that it is neutral, when in fact it is a snake in the grass!
QFP is one of those packages that seems just like SOIC on paper but turns out to be a huge pain in the ass to assemble and rework in practice. so many solder bridges hiding under those legs.
@erincandescent@DM_Ronin also quite annoying but with QFN you usually get the extra complexity of it being hard to grip with tweezers, plus the two different dimensions of alignment so if you slip in any direction you end up creating bridges.
@DM_Ronin lol yeah some of these seem to be categorised by just the perception of what they're like, or how weird the package looks. the wire bonded CoB package being chaotic evil is definitely true though.
@gsuberland seems that way. Though I'd have assigned Soviet one as a solid contender to be a chaotic neutral - considering they have gold-plated lead frames, according to some descriptions (although it might be they meant gold color)
@DM_Ronin they're gold plated. Soviet ICs were almost exclusively produced out of state operated facilities that primarily serviced the military and aeronautic sectors, and there wasn't really any point in retooling the leadframe production lines for cheaper metals at the scales they operated at.
"Oh, you've used 2% too much paste there"
"Oh, you've placed that resistor too close to the QFN, it shielded the heat and didn't reflow properly"
🔥 😡
I think most, almost all of my assembly failures were QFN-related. The other ones were either just stupid (orientation, etc.) or legit solder bridges on QFP.
@manawyrm@DM_Ronin ah I just tend to hand solder QFNs. preheat board with hot air, plenty of flux, tin the pads, hot air again, iron on the ground pad, drop the QFN on, then drag solder the edges to get good contact. mop up any extra with wick.
the main trick I've used when sending boards for assembly is to split the ground pad paste mask into a grid instead of using one big square. usually 3x3 or more separate paste mask apertures.
@gsuberland@manawyrm@DM_Ronin
That seems to often be the suggested paste mask by manufacturers as well.
3x23 or the lesser 2x2 grid instead of on large plate.
I have extremely good yield on QFN, most of my problems have been on QFPs. It's one of the reasons that I have a soft ban on TQFP/TSSOP packages in my designs (only consider a TQFP/SSOP if no QFN/BGA packaged part can be found that meets the requirements).
And when I do have a problem on a QFN it's usually very obvious.
@azonenberg@ftg@manawyrm@DM_Ronin on this note, d'you know what the actual justification for using aperture grids is over one single large aperture? I always assumed it was just about ensuring paste uniformity and avoiding excess application, and maybe providing some channels for offgassing if the paste is older or the part wasn't properly humidity controlled, but I never looked into the details.
@niconiconi@gsuberland@DM_Ronin I can do CT inspection on small boards (small enough to fit in all rotations into the chamber), but that's not often the case.
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