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cracked capacitors at SMT 1&2

M.Enright

#30035

cracked capacitors at SMT 1&2 | 16 August, 2004

Currently we have an issue with cracked capacitors at SMT 1&2. We have seen several different types of capacitors cracked on at least three different products. We are using an "Universal 4796 HSP".This has been checked by a rep from "Universal" who could find nothing wrong with the machine. Support under the board during placement is ok.We are using plastic support pins and not a "Nest fixture". We have seen the cracked capacitors pre-reflow. We have checked the oven and made sure everything was OK there.It was fine. Conveyors etc have all checked out ok.Feeders have been checked to ensure they have been calibrated. It occurrs maybe one in 300 units built. Has any one else had this issue and if so,can you offer some assistance in to how we can eliminate this issue?.

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#30041

cracked capacitors at SMT 1&2 | 16 August, 2004

A little more information, please: * Describe the location and pattern of your cracks * Tell us the type of capacitor that you're destroying

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M.Enright

#30072

cracked capacitors at SMT 1&2 | 17 August, 2004

Some cracks are really obvious,straight down the middle of the capacitor.Some are slight hair line fractures which fail at ICT.In all cases seen,all cracks are through the centre of the cap.My worry is that there may be some which have fractures and are passing test.

Components are cracking on different areas of the boards,at both SMT1&2.Some are found cracked pre-reflow.

The types of capacitors involved are 1206 ceramic caps,ranging in values from 10nf to 330pf.We have indentified at least eight different values so far.

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Rob

#30075

cracked capacitors at SMT 1&2 | 17 August, 2004

Hi,

I'm not the expert DaveF is, however I have seen quite a few cracked chip capaictors in my time - most of these were from lack of Z height adjustment on a turret chipshooter to compensate for various thickness.

Do you have separate 1206 thicknesses in your machine library, or are all of the 1206 Cap treated the same?

Cheers,

Rob

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#30080

cracked capacitors at SMT 1&2 | 17 August, 2004

Do a search on cracked caps in the search bar above. There is lots of past history for alot of us in this area.

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#30086

cracked capacitors at SMT 1&2 | 17 August, 2004

We agree with Rob. It sounds like someone is trying to pound your caps through the board.

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M.Enright

#30101

cracked capacitors at SMT 1&2 | 18 August, 2004

We have Z height adjustment on a turret chipshooter to compensate for various thickness. At the moment all the 1206 Cap are treated the same.It's something we are going to change over the next few weeks. Thanks for your help!.

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pr

#30103

cracked capacitors at SMT 1&2 | 18 August, 2004

Is this the first pass or second? We have found the screen printer on the 2nd pass to be the culprit more often than not.

let us know your results, pr

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M.Enright

#30106

cracked capacitors at SMT 1&2 | 18 August, 2004

We are finding cracked capacitors at both first pass and second pass.

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Art

#30121

cracked capacitors at SMT 1&2 | 19 August, 2004

If you have the placement feedback enabled this should not be an issue. Are all of these parts from the same supplier? If so who is it? We are currently having a very simular issue.

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M.Enright

#30126

cracked capacitors at SMT 1&2 | 19 August, 2004

Are all of these parts from the same supplier? No. We have three different suppliers,AVX,Dublier and Kemet.We have had cracked capacitors from reels of each of these suppliers.

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vickt

#31042

cracked capacitors at SMT 1&2 | 20 October, 2004

M.Enright, Is this problem resolved yet? Please let us know at HSP TECHS@UIC.COM

regards..

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#31048

cracked capacitors at SMT 1&2 | 21 October, 2004

Have been through this before and we resolved our problem as follows: 1.Make sure that the length of your board support pins on Your HSP is correct. On that machine the board support pins depends on the board thickness (+ - some tenth's of a mm). It's in the machine manual. 2. Secondary side mounting: make sure that the location of the support pins are correct, so they don't hit any component. That goes for every machine in the line. 3. Check Z-axis adjustment. 4. The nozzles on that machine is spring loaded; check this also, so that the nozzles can move up/down with correct force.

I Hope this helps, Regards

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Indy

#31054

cracked capacitors at SMT 1&2 | 21 October, 2004

I have seens cracks from AVX capacitors too. The thing is they already have micro cracks that are not visible to naked eye. When the capacitor is stressed the crack expands. One way of mitigating this is by tweeking your process. See how your singulate your PCB array. Check how close your capacitor is to the edge of the PCB.

Indy

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Simon UK

#31065

cracked capacitors at SMT 1&2 | 22 October, 2004

I have experienced this same problem with CECC Type caps, in all sizes.

One cause, which may have not been explored is the component may hav been cracked before you placed it 1 in 300? Hmm..I did this on our products that were showning atleast 5 per board, it turns out our manufacturer's were at fault, but on after expensive cross sectional analysis.

I hope you weed out the root cause! Simon

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Adnahn

#31072

cracked capacitors at SMT 1&2 | 25 October, 2004

I agree with DaveF and Rob.Also check the nozzle for any rough surfaces.

Good Luck.

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bobpan

#31075

cracked capacitors at SMT 1&2 | 25 October, 2004

I have seen tooling cause cracked capacitors.....are the plastic standoffs compliant???? If they are not.....this could be the cause....

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