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Re: Cracked Capacitors

John Hardy

#11083

Cracked Capacitors | 11 June, 1999

Our company is experiencing cracked caps at our pick and place operations. The caps are being placed onto epoxy dots for subsequent wave solder operations. At present, be have set the pressure of the head at 2 in/lbs. This being down from manufacturers recommendation of 3.5 to 5 in/lbs. The caps appear to be chipping from the edge of the component toward the center, with the largest mass being chipped near the edge. If anyone has experienced similar problems, would you please contact me with your resolution. This is becoming very frustrating for us. Any help would be greatly appreciated.

Thanks, John

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Dean

#11084

Re: Cracked Capacitors | 12 June, 1999

| Our company is experiencing cracked caps at our pick and place operations. The caps are being placed onto epoxy dots for subsequent wave solder operations. At present, be have set the pressure of the head at 2 in/lbs. This being down from manufacturers recommendation of 3.5 to 5 in/lbs. The caps appear to be chipping from the edge of the component toward the center, with the largest mass being chipped near the edge. If anyone has experienced similar problems, would you please contact me with your resolution. This is becoming very frustrating for us. Any help would be greatly appreciated. | | Thanks, John | Wow! Blast from the past. I haven't seen this problem in ten years. Back then I was a support technician in a shop which used Dynapert 500's and 318's. (Back then this was solid equipment --OK) The component centering technique used "tweezering". Essentially, centering jaws mechanically centered the component on the pickup tool. The jaw centering speed was set by air regulators. If the incomming centering speed was too fast, it could fracture and chip the cap or resistor (or bend leads on IC's). Also, the height at which the jaws contacted the chip was equally important. If too high, it could chip the edges (near the center) of the part. Therefore, the part needed to be lower to contact the jaws in the center of the chip cap to take the brunt of force. Another problem associated was if the pickup tool becam "sticky" and could not travel freely in its bronz shaft. This would affect centering height and give inconsistent results (occasional cracking). Also check your tooling force at the point of placement (mount height). Typicall you get a fracture or divot in the center of the chip if you have excessive tooling force at the mount position (Z height, mount height , tooling force -- all the same thing).

If you have isolated this problem to your P&P equipment, 90 % of the battle is done. Thanks for the trip down memory lane. My last experience with touch centering was a Zervatech PPM9. From there it has been touch-less centering. Cracked parts were a thing of the past (plus placement speeds went through the roof in the industry!) Enjoy, Dean

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JohnW

#11085

Re: Cracked Capacitors | 12 June, 1999

| | Our company is experiencing cracked caps at our pick and place operations. The caps are being placed onto epoxy dots for subsequent wave solder operations. At present, be have set the pressure of the head at 2 in/lbs. This being down from manufacturers recommendation of 3.5 to 5 in/lbs. The caps appear to be chipping from the edge of the component toward the center, with the largest mass being chipped near the edge. If anyone has experienced similar problems, would you please contact me with your resolution. This is becoming very frustrating for us. Any help would be greatly appreciated. | | | | Thanks, John | | | Wow! Blast from the past. I haven't seen this problem in ten years. Back then I was a support technician in a shop which used Dynapert 500's and 318's. (Back then this was solid equipment --OK) | The component centering technique used "tweezering". Essentially, centering jaws mechanically centered the component on the pickup tool. The jaw centering speed was set by air regulators. If the incomming centering speed was too fast, it could fracture and chip the cap or resistor (or bend leads on IC's). Also, the height at which the jaws contacted the chip was equally important. If too high, it could chip the edges (near the center) of the part. Therefore, the part needed to be lower to contact the jaws in the center of the chip cap to take the brunt of force. | Another problem associated was if the pickup tool becam "sticky" and could not travel freely in its bronz shaft. This would affect centering height and give inconsistent results (occasional cracking). | Also check your tooling force at the point of placement (mount height). Typicall you get a fracture or divot in the center of the chip if you have excessive tooling force at the mount position (Z height, mount height , tooling force -- all the same thing). | | If you have isolated this problem to your P&P equipment, 90 % of the battle is done. | Thanks for the trip down memory lane. My last experience with touch centering was a Zervatech PPM9. From there it has been touch-less centering. Cracked parts were a thing of the past (plus placement speeds went through the roof in the industry!) | Enjoy, | Dean | | John, I'm taking it for granted that your checking the component's at the following points 1. As you reel them up to the feeder ( that way you know they r ok going onto the machine) 2. After thay have been placed but prior to the epoxy being cured ( this will rule out the placement machine) 3. After they come out the oven..

Here's why I'm asking.... I've seen something similar with MELF packages...we went through the same exercise as dean's suggesting above and got nowhere, we checked the profiles and got know where..turned out it was related to the epoxy. Quick question..are you placing these part's on paste as well at some other point or on some other board??? if so are they cracking then??? We had melf's cracking on epoxy but not on the paste. Turns out what was basically happening was that as the epoxy cures it will loose moisture and the epoxy basically 'shrinks' usually it's already got a pretty good hold on the component at this point and the component actually breaks. A good way to rule this out is paste a board and place the cap's on it, glue a board and place the cap's on it and see what happens at the other end of the oven.

Hope this helps

JohnW

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Adam Pratt

#11086

Re: Cracked Capacitors | 14 June, 1999

| | | Our company is experiencing cracked caps at our pick and place operations. The caps are being placed onto epoxy dots for subsequent wave solder operations. At present, be have set the pressure of the head at 2 in/lbs. This being down from manufacturers recommendation of 3.5 to 5 in/lbs. The caps appear to be chipping from the edge of the component toward the center, with the largest mass being chipped near the edge. If anyone has experienced similar problems, would you please contact me with your resolution. This is becoming very frustrating for us. Any help would be greatly appreciated. | | | | | | Thanks, John | | | | | Wow! Blast from the past. I haven't seen this problem in ten years. Back then I was a support technician in a shop which used Dynapert 500's and 318's. (Back then this was solid equipment --OK) | | The component centering technique used "tweezering". Essentially, centering jaws mechanically centered the component on the pickup tool. The jaw centering speed was set by air regulators. If the incomming centering speed was too fast, it could fracture and chip the cap or resistor (or bend leads on IC's). Also, the height at which the jaws contacted the chip was equally important. If too high, it could chip the edges (near the center) of the part. Therefore, the part needed to be lower to contact the jaws in the center of the chip cap to take the brunt of force. | | Another problem associated was if the pickup tool becam "sticky" and could not travel freely in its bronz shaft. This would affect centering height and give inconsistent results (occasional cracking). | | Also check your tooling force at the point of placement (mount height). Typicall you get a fracture or divot in the center of the chip if you have excessive tooling force at the mount position (Z height, mount height , tooling force -- all the same thing). | | | | If you have isolated this problem to your P&P equipment, 90 % of the battle is done. | | Thanks for the trip down memory lane. My last experience with touch centering was a Zervatech PPM9. From there it has been touch-less centering. Cracked parts were a thing of the past (plus placement speeds went through the roof in the industry!) | | Enjoy, | | Dean | | | | | John, | I'm taking it for granted that your checking the component's at the following points | 1. As you reel them up to the feeder ( that way you know they r ok going onto the machine) | 2. After thay have been placed but prior to the epoxy being cured | ( this will rule out the placement machine) | 3. After they come out the oven.. | | Here's why I'm asking.... | I've seen something similar with MELF packages...we went through the same exercise as dean's suggesting above and got nowhere, we checked the profiles and got know where..turned out it was related to the epoxy. Quick question..are you placing these part's on paste as well at some other point or on some other board??? if so are they cracking then??? | We had melf's cracking on epoxy but not on the paste. Turns out what was basically happening was that as the epoxy cures it will loose moisture and the epoxy basically 'shrinks' usually it's already got a pretty good hold on the component at this point and the component actually breaks. | A good way to rule this out is paste a board and place the cap's on it, glue a board and place the cap's on it and see what happens at the other end of the oven. | | Hope this helps | | JohnW | We have experienced this situation in the past but not with an adhesive process. If you are cracking the caps with paste and adhesive you may need to relocate the coordinate where the head checks the board height. You may also need to re-install the tool that you are using to place the caps.

Good Luck

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Marshall

#11087

Re: Cracked Capacitors | 14 June, 1999

| | | | Our company is experiencing cracked caps at our pick and place operations. The caps are being placed onto epoxy dots for subsequent wave solder operations. At present, be have set the pressure of the head at 2 in/lbs. This being down from manufacturers recommendation of 3.5 to 5 in/lbs. The caps appear to be chipping from the edge of the component toward the center, with the largest mass being chipped near the edge. If anyone has experienced similar problems, would you please contact me with your resolution. This is becoming very frustrating for us. Any help would be greatly appreciated. | | | | | | | | Thanks, John | | | | | | | Wow! Blast from the past. I haven't seen this problem in ten years. Back then I was a support technician in a shop which used Dynapert 500's and 318's. (Back then this was solid equipment --OK) | | | The component centering technique used "tweezering". Essentially, centering jaws mechanically centered the component on the pickup tool. The jaw centering speed was set by air regulators. If the incomming centering speed was too fast, it could fracture and chip the cap or resistor (or bend leads on IC's). Also, the height at which the jaws contacted the chip was equally important. If too high, it could chip the edges (near the center) of the part. Therefore, the part needed to be lower to contact the jaws in the center of the chip cap to take the brunt of force. | | | Another problem associated was if the pickup tool becam "sticky" and could not travel freely in its bronz shaft. This would affect centering height and give inconsistent results (occasional cracking). | | | Also check your tooling force at the point of placement (mount height). Typicall you get a fracture or divot in the center of the chip if you have excessive tooling force at the mount position (Z height, mount height , tooling force -- all the same thing). | | | | | | If you have isolated this problem to your P&P equipment, 90 % of the battle is done. | | | Thanks for the trip down memory lane. My last experience with touch centering was a Zervatech PPM9. From there it has been touch-less centering. Cracked parts were a thing of the past (plus placement speeds went through the roof in the industry!) | | | Enjoy, | | | Dean | | | | | | | | John, | | I'm taking it for granted that your checking the component's at the following points | | 1. As you reel them up to the feeder ( that way you know they r ok going onto the machine) | | 2. After thay have been placed but prior to the epoxy being cured | | ( this will rule out the placement machine) | | 3. After they come out the oven.. | | | | Here's why I'm asking.... | | I've seen something similar with MELF packages...we went through the same exercise as dean's suggesting above and got nowhere, we checked the profiles and got know where..turned out it was related to the epoxy. Quick question..are you placing these part's on paste as well at some other point or on some other board??? if so are they cracking then??? | | We had melf's cracking on epoxy but not on the paste. Turns out what was basically happening was that as the epoxy cures it will loose moisture and the epoxy basically 'shrinks' usually it's already got a pretty good hold on the component at this point and the component actually breaks. | | A good way to rule this out is paste a board and place the cap's on it, glue a board and place the cap's on it and see what happens at the other end of the oven. | | | | Hope this helps | | | | JohnW | | | We have experienced this situation in the past but not with an adhesive process. If you are cracking the caps with paste and adhesive you may need to relocate the coordinate where the head checks the board height. You may also need to re-install the tool that you are using to place the caps. | | Good Luck | John, Here may be the simplest checks. 1. Check the support pins inside your work nest. 2. Verify that you are not exceding 2 degrees C per sec. in reflow and that your peak temps are not over 215 degrees C. You may also be using some other reflow oven than a BTU or Conceptronic. 3. Verify that your pre-heat temps inside your wave are not exceding 190-200 degrees C just before the product goes over the wave. It's not the adhesive and glass is alot more brittle than ceramic.

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Ron G. Belliard, EET

#11088

Re: Cracked Capacitors | 17 June, 1999

RE: Cracked Capacitors: I have worked for 3 1/2 yrs with SMTA and have found a similar problem with capacitors. Throughout my studies of the problem, I have discovered three contributing factors that caused this cracking either individually or in combination. 1) The moisture levels in the warehouse were too high. We ended up solving this problem by sealing our reels after each use by using an impulse sealer. 2) The peak temperature of the oven surpassed the requirements of the capacitor manufacturer and we were forced to re-profile the oven's performance. 3) The supplier had sub-standard storage environments and the components were contaminated before we even received them. An inspection of their premises (ISO) lead us to contracting a new supplier.

Hope this information is helpful.

| Our company is experiencing cracked caps at our pick and place operations. The caps are being placed onto epoxy dots for subsequent wave solder operations. At present, be have set the pressure of the head at 2 in/lbs. This being down from manufacturers recommendation of 3.5 to 5 in/lbs. The caps appear to be chipping from the edge of the component toward the center, with the largest mass being chipped near the edge. If anyone has experienced similar problems, would you please contact me with your resolution. This is becoming very frustrating for us. Any help would be greatly appreciated. | | Thanks, John |

reply »

Brian Wycoff

#11089

Re: Cracked Capacitors | 17 June, 1999

| | | | | Our company is experiencing cracked caps at our pick and place operations. The caps are being placed onto epoxy dots for subsequent wave solder operations. At present, be have set the pressure of the head at 2 in/lbs. This being down from manufacturers recommendation of 3.5 to 5 in/lbs. The caps appear to be chipping from the edge of the component toward the center, with the largest mass being chipped near the edge. If anyone has experienced similar problems, would you please contact me with your resolution. This is becoming very frustrating for us. Any help would be greatly appreciated. | | | | | | | | | | Thanks, John | | | | | | | | | Wow! Blast from the past. I haven't seen this problem in ten years. Back then I was a support technician in a shop which used Dynapert 500's and 318's. (Back then this was solid equipment --OK) | | | | The component centering technique used "tweezering". Essentially, centering jaws mechanically centered the component on the pickup tool. The jaw centering speed was set by air regulators. If the incomming centering speed was too fast, it could fracture and chip the cap or resistor (or bend leads on IC's). Also, the height at which the jaws contacted the chip was equally important. If too high, it could chip the edges (near the center) of the part. Therefore, the part needed to be lower to contact the jaws in the center of the chip cap to take the brunt of force. | | | | Another problem associated was if the pickup tool becam "sticky" and could not travel freely in its bronz shaft. This would affect centering height and give inconsistent results (occasional cracking). | | | | Also check your tooling force at the point of placement (mount height). Typicall you get a fracture or divot in the center of the chip if you have excessive tooling force at the mount position (Z height, mount height , tooling force -- all the same thing). | | | | | | | | If you have isolated this problem to your P&P equipment, 90 % of the battle is done. | | | | Thanks for the trip down memory lane. My last experience with touch centering was a Zervatech PPM9. From there it has been touch-less centering. Cracked parts were a thing of the past (plus placement speeds went through the roof in the industry!) | | | | Enjoy, | | | | Dean | | | | | | | | | | | John, | | | I'm taking it for granted that your checking the component's at the following points | | | 1. As you reel them up to the feeder ( that way you know they r ok going onto the machine) | | | 2. After thay have been placed but prior to the epoxy being cured | | | ( this will rule out the placement machine) | | | 3. After they come out the oven.. | | | | | | Here's why I'm asking.... | | | I've seen something similar with MELF packages...we went through the same exercise as dean's suggesting above and got nowhere, we checked the profiles and got know where..turned out it was related to the epoxy. Quick question..are you placing these part's on paste as well at some other point or on some other board??? if so are they cracking then??? | | | We had melf's cracking on epoxy but not on the paste. Turns out what was basically happening was that as the epoxy cures it will loose moisture and the epoxy basically 'shrinks' usually it's already got a pretty good hold on the component at this point and the component actually breaks. | | | A good way to rule this out is paste a board and place the cap's on it, glue a board and place the cap's on it and see what happens at the other end of the oven. | | | | | | Hope this helps | | | | | | JohnW | | | | | We have experienced this situation in the past but not with an adhesive process. If you are cracking the caps with paste and adhesive you may need to relocate the coordinate where the head checks the board height. You may also need to re-install the tool that you are using to place the caps. | | | | Good Luck | | | John, | Here may be the simplest checks. | 1. Check the support pins inside your work nest. | 2. Verify that you are not exceding 2 degrees C per sec. in reflow and that your peak temps are not over 215 degrees C. You may also be using some other reflow oven than a BTU or Conceptronic. | 3. Verify that your pre-heat temps inside your wave are not exceding 190-200 degrees C just before the product goes over the wave. | It's not the adhesive and glass is alot more brittle than ceramic. | | We had the problem in two places. One side of the component cooled faster than the other, providing the mechanical stress. The part did not tombstone. The other cause was from mechanical stress from the separation of the panel or the installation of the board into the housing. The same components on each board cracked along the board flex line.

Brian

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Ian Clelland

#11090

Re: Cracked Capacitors | 17 June, 1999

| | | | | | Our company is experiencing cracked caps at our pick and place operations. The caps are being placed onto epoxy dots for subsequent wave solder operations. At present, be have set the pressure of the head at 2 in/lbs. This being down from manufacturers recommendation of 3.5 to 5 in/lbs. The caps appear to be chipping from the edge of the component toward the center, with the largest mass being chipped near the edge. If anyone has experienced similar problems, would you please contact me with your resolution. This is becoming very frustrating for us. Any help would be greatly appreciated. | | | | | | | | | | | | Thanks, John | | | | | | | | | | | Wow! Blast from the past. I haven't seen this problem in ten years. Back then I was a support technician in a shop which used Dynapert 500's and 318's. (Back then this was solid equipment --OK) | | | | | The component centering technique used "tweezering". Essentially, centering jaws mechanically centered the component on the pickup tool. The jaw centering speed was set by air regulators. If the incomming centering speed was too fast, it could fracture and chip the cap or resistor (or bend leads on IC's). Also, the height at which the jaws contacted the chip was equally important. If too high, it could chip the edges (near the center) of the part. Therefore, the part needed to be lower to contact the jaws in the center of the chip cap to take the brunt of force. | | | | | Another problem associated was if the pickup tool becam "sticky" and could not travel freely in its bronz shaft. This would affect centering height and give inconsistent results (occasional cracking). | | | | | Also check your tooling force at the point of placement (mount height). Typicall you get a fracture or divot in the center of the chip if you have excessive tooling force at the mount position (Z height, mount height , tooling force -- all the same thing). | | | | | | | | | | If you have isolated this problem to your P&P equipment, 90 % of the battle is done. | | | | | Thanks for the trip down memory lane. My last experience with touch centering was a Zervatech PPM9. From there it has been touch-less centering. Cracked parts were a thing of the past (plus placement speeds went through the roof in the industry!) | | | | | Enjoy, | | | | | Dean | | | | | | | | | | | | | | John, | | | | I'm taking it for granted that your checking the component's at the following points | | | | 1. As you reel them up to the feeder ( that way you know they r ok going onto the machine) | | | | 2. After thay have been placed but prior to the epoxy being cured | | | | ( this will rule out the placement machine) | | | | 3. After they come out the oven.. | | | | | | | | Here's why I'm asking.... | | | | I've seen something similar with MELF packages...we went through the same exercise as dean's suggesting above and got nowhere, we checked the profiles and got know where..turned out it was related to the epoxy. Quick question..are you placing these part's on paste as well at some other point or on some other board??? if so are they cracking then??? | | | | We had melf's cracking on epoxy but not on the paste. Turns out what was basically happening was that as the epoxy cures it will loose moisture and the epoxy basically 'shrinks' usually it's already got a pretty good hold on the component at this point and the component actually breaks. | | | | A good way to rule this out is paste a board and place the cap's on it, glue a board and place the cap's on it and see what happens at the other end of the oven. | | | | | | | | Hope this helps | | | | | | | | JohnW | | | | | | | We have experienced this situation in the past but not with an adhesive process. If you are cracking the caps with paste and adhesive you may need to relocate the coordinate where the head checks the board height. You may also need to re-install the tool that you are using to place the caps. | | | | | | Good Luck | | | | | John, | | Here may be the simplest checks. | | 1. Check the support pins inside your work nest. | | 2. Verify that you are not exceding 2 degrees C per sec. in reflow and that your peak temps are not over 215 degrees C. You may also be using some other reflow oven than a BTU or Conceptronic. | | 3. Verify that your pre-heat temps inside your wave are not exceding 190-200 degrees C just before the product goes over the wave. | | It's not the adhesive and glass is alot more brittle than ceramic. | | | | | We had the problem in two places. One side of the component cooled faster than the other, providing the mechanical stress. The part did not tombstone. The other cause was from mechanical stress from the separation of the panel or the installation of the board into the housing. The same components on each board cracked along the board flex line. | | Brian |

One thing to look for nowadays is the habit of MLCC makers to substitute Nickel based electrodes for the older, and more dutile palladium/silver electrodes and termination systems. We have noticed the newer nickel based chips are far more fragile than in the past. They are also shorting and blowing up, but this is another matter entirely. Ian Clelland

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