| I've never seen this before. Today, I got this tombstoning on Tantalum Capacitors (Okay, I saw that before) | Here's the part that seems weird to me: | -They didn't tombstone onto a termination - they went onto their sides! That's right, both termination ends are on the pads, but the caps are resting vertically instead of horizontally. They're three sided termiations, so now there's no termination in the solder, just the sides of the cap. | -They all went in the same direction - onto, say, their left sides. | -There's about six per board in different areas and orientations, but they all flipped onto the same side. It's almost as if they were placed that way. | -One of them is even getting placed on an aluminum electrolytic cap footprint - same thing, same side | -Nothing else tombstoned - just this part number | -It didn't happen on all the boards, but where it happened in groups (all six parts would be up on their edge) | Screen prints were good - running a UP3000 with a brand new stencil | Placements were good - from a calibrated, maintained Siemens 80S | Reflow profile is a little aggressive on the ramp (~3C/sec), but gets a thorough soak at 165, spikes to 206-223 for a max of 70 seconds above liquidus. | I didn't see each particular board before it hit the reflow oven, but these are generally no-brainers. A production worker downstream noticed it today (after the run finished up, of course) | Anybody seen anything like this before? Got any insights as to what's going on here? Any info would be appreciated. | Thanks, | Chrys Chrys, I guess you didn't hear about the occurance of the grouping of planetary alignment factor that is matching with the coming of the new moon, it only happens once every 5.25 years...on those days the gravatational forces fluctuate to cause the polarized ends of capacitors to rotate to the left..........not buyin' that huh?...didn't think you would....hehehe. What size are these puppies? Case A, B, C, or D? I've seen something like this before, and you probably got it right when you said that it looked like it was placed that way. There's two things that it could be, one, the feeder was mis-indexed, and the machine picked the part right at the edge, so that when the nozzle was coming back up, gravity or the sides of the pocket caused the part to kinda' rotate to it's side on the nozzle...to a billboard. You seen that happen with smaller parts haven't you? It mostly happens with 0805's or 3216's. One other possibility was that the parts were taped-up that way in the reel...I've seen that happen too. With certain case-sized tantalums, they look the same in the camera whether they're on their sides or facing in the right direction because the outline dimension is the same no matter which way they're on the nozzle...so a camera that is looking at a silouette won't see any difference. Maybe check some other reels of the same part number (if you have any) to see if there are any reels that have that problem. Other than that, I can't think of what in the world would cause something like that! 'Cept the planet alignment thing...(GRIN) -Steve Gregory- PS- Let us know what you find out, this ones a doozy!!!
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