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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Chrys

#16021

Wierd Tombstoning on Tant Caps | 1 May, 1998

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

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Earl Moon

#16027

Re: Wierd Tombstoning on Tant Caps | 1 May, 1998

| 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, Check devices for oxidation or other contamination - solderability - "wetting." Just a thought as though device termination areas may be contaminated exhibiting the same characteristics effecting them to "jump" off their specified placement areas. Earl Moon

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Steve Gregory

#16026

Re: Wierd Tombstoning on Tant Caps | 1 May, 1998

| 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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D.Lange

#16025

Re: Wierd Tombstoning on Tant Caps | 1 May, 1998

| 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 Yep! Know what you are talkin. Have had the same problem with other packages. May not be noticeable to the naked eye but if you pull up gerbers and note if there are any thermal masses common to "the left side" of these parts then these parts will pull towards these masses. Are there power planes or ground planes or any other thermal masses (copper) common to these locations. talk to your design engineer and have him view the locations which this is occurring I'd be willing to bet your paycheck that there are common thermal masses associated with these locations.

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Rick

#16024

Re: Wierd Tombstoning on Tant Caps | 2 May, 1998

I agree with Steve...most certainly a placement occurance. I've seen this on many occasions with Panasonic equip. Change your feeder first and then check your component packaging. | 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

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ETS, LLC

#16023

Re: Wierd Tombstoning on Tant Caps | 4 May, 1998

As an employee of a Reflow Oven Manufacturer I can only make suggestions on the oven portion of your process: As I was reading through your posting I started wondering if you are using a convection or IR based oven. If you are using Convection I would consider the way that the boards are loaded vs. the direction that the RHA blower wheels force the air to move. In addition I was concerned with your ramp rate. Why such a quick rise? Is your oven too short. I was also concerned with the NON-Uniformity in temperatures. Can you explain your statement of peaks being 206 - 223C ? Is this recorded on various points of the same board or is this temps recorded on a couple different boards? If these temps are recorded off different points of the same board then I would have to agree with the statement about thermal masses near to the problem. Hope this helps, Brian Stumm ETS, LLC 509-483-0900 (voice) 509-483-0331 (fax) ets@eznet.com (e-mail)

| 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

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Dave F

#16022

Re: Wierd Tombstoning on Tant Caps | 4 May, 1998

| 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: Contining with the thought that you are picking-up mis-oriented components, I've seen two types of cover tape problems that may help explain what you are seeing: 1. Cover tape does not release properly, causing components to "hop" 2. Cover tape is electrostaiclly charged, causing components to be "attached" to the tape Dave

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Chrys

#16028

Re: Wierd Tombstoning on Tant Caps | 5 May, 1998

| | 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, | Check devices for oxidation or other contamination - | solderability - "wetting." | Just a thought as though device termination areas | may be contaminated exhibiting the same characteristics | effecting them to "jump" off their specified placement | areas. | Earl Moon Thanks for all your inputs! My favorite theory is the planetary alignment one. It could actually be used to explain a lot of odd phenomena around here. The thermal masses are a bit odd in this board (as witness during wave solder profiling, as well), but I've inherited it from another factory an don't have a full set of documentation. I think the most probable place to look is in the placement. Now that you folks, have mentioned it, I have seen similarly goofy placement when my nozzles need replacement. And since we have an automatic nozzle changers that rotates through the set, it would explain why I saw it on every componenet for a string of baords, but not the whole run. Thanks again. I'm off to replace some dirty, old, worn nozzles now.

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Earl Moon

#16029

Re: Wierd Tombstoning on Tant Caps | 15 May, 1998

| | | 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, | | Check devices for oxidation or other contamination - | | solderability - "wetting." | | Just a thought as though device termination areas | | may be contaminated exhibiting the same characteristics | | effecting them to "jump" off their specified placement | | areas. | | Earl Moon | Thanks for all your inputs! My favorite theory is the planetary alignment one. It could actually be used to explain a lot of odd phenomena around here. | The thermal masses are a bit odd in this board (as witness during wave solder profiling, as well), but I've inherited it from another factory an don't have a full set of documentation. I think the most probable place to look is in the placement. Now that you folks, have mentioned it, I have seen similarly goofy placement when my nozzles need replacement. And since we have an automatic nozzle changers that rotates through the set, it would explain why I saw it on every componenet for a string of baords, but | not the whole run. | Thanks again. I'm off to replace some dirty, old, worn nozzles now. Chrys, The answer always lies in the stars - unless you had the answer all the time. Your just toying with the rest of us. Go chase the dirt wherever it is found, Earl

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