Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Unsoldered Component

Dolan

#7507

Unsoldered Component | 31 July, 2001

i have a problem with some units that had one capacitor only soldered in one side, the geometry of the capacitor is 0805, our product during his life suffer a lot of stress (due temperature or vibration), some of those units are already with the costumer, and we are trying to determine the possible risk that this could involve, our experts from germany and United States do not have any idea about the possible risk, so what i want ot know is: It is possible that component fall form the pcb?, due a possible crack of the solder.

Thanks for your help!, i really appreciate it.

reply »

#7512

Unsoldered Component | 31 July, 2001

If you've told your experts in Germany and US as little as you've told us, I'm not surprised they don't know dip.

Sorry, I just snapped there for a moment. That wasn't politic, was it?

Yes, it is possible that the other solder connection on this capacitor could crack as a result of vibratory stress. This would allow the part to break loose and tumble into the innards of your machine, causing untold damage and distruction.

Consider submitting several of these boards to an environmental testing laboratory for accelerated life cycle testing to give you a better idea of the range of possibilities. IPC [http://www.ipc.org] lists organizations capable of performing these tests.

reply »

Brent Taylor

#7523

Unsoldered Component | 1 August, 2001

We have this problem with our High Temp. solder lines. Tombstoning is actually the term used in our facility. We found that the component termination width was a main contributor also profile ramp rates. Visual inspection will catch most of these rejects and electrical testing will catch the rest. If these rejects get into the field they will fail, all of our testing shows this.

reply »

Brent Taylor

#7524

Unsoldered Component | 1 August, 2001

We have this problem with our High Temp. solder lines. Tombstoning is actually the term used in our facility. We found that the component termination width was a main contributor also profile ramp rates. Visual inspection will catch most of these rejects and electrical testing will catch the rest. If these rejects get into the field they will fail, all of our testing shows this.

reply »

mugen

#7552

Unsoldered Component | 3 August, 2001

Well none of us, really know whether, this 0805 CAP is really an unsolder/tombstone defect, coz none of us verfied this with, our own eyes *duh*

Funny, this only happened for us, on 0402 ~ 0201 SMD....

Check your land-pad design specifications, if your design team insists the PCB, is in compliance to IPC design specs, try a switch to the relevant Jap standards, they *jap* have closer footprints specs, that help gap that iffy-pitty gap distance, that could contribute to tombstone/unsolder defects.... (sorry, can't remember exact Jap standards' name)

What also works, is to commission, ur own change of stencil fabrication, by having the problematic PCB pads, changed from one-opening Stencil, into twin-opening Stencil, and pls still retain the orginal, stencil opening area, of the respective problematic aperature....

Basic thing to do though, before you thrash into the bushes, with the above two suggestions, is to confirm what printing parameters, you have established, and what solder paste data readings, you have collected via SPC, and get the QA+process guys, to verify paste volume deposits, are within appropriate levels? (by far the easy step to commence with, each glorious monday morning....)

reply »

Dolan

#17083

Unsoldered Component | 3 August, 2001

Hi again!

First thanks to all for your help. Second, i beleive that i need to clarify something, the unsoldered component was caused due a missing window in the stencil, the process engineer leave the stencil in the production line after it fail the release(well a stupid mistake - and sorry for the word but that is the truth)... so in the pad and of course in the component do not have solder paste. The process engineer believe that the soldered side of the component have a good solder joint, and if it is going to fail is because the component could broke. We already measure the solder paste in this point and the values are acording the specification (150 to 220 micras), and also the solder paste have good weeting. for more information We are using solder paste Kester 256.

Well, again thanks for your help, and for me is possible to send a picture of the unit, if it is necesary.

reply »

SP700avi inline stencil printer

ii-feed SMD Intelligent Feeder