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0603 Components

Sal

#3074

0603 Components | 9 September, 2000

Guys

A very concerned engineer. Just been called over look at some PCB's in our diag area for missing components(0603).Too my shock I have just found that these components can be picked off just using a finger and applying some pressure. And apparently this has been going on for some time now. The solder remains on the pads but the components themselves are falling off. Can anyone please explain this phenomenen and what how to rectify this, also do I have a product reliability issue ? The Boards are both Entek and Gold finishes.

Sal.

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david_

#3075

Re: 0603 Components | 10 September, 2000

Just from my experience in seeing a problem like this is as follows

The part has not been centered over the pads when placed, and during reflow the part is dragged over the the side with the most contact. Two, the parts are being dropped into the Pcb durnng placement and might be sitting on top of the paste rather then being seated into the paste. And three, there just might not be enough solder on the pad. I hope this helps and I am sure someone might give you a more definitive answer.

Dave

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Jim Arnold

#3076

Re: 0603 Components | 11 September, 2000

I spent 25 years operating my own hybrid shop working with surface mount components, soldering materials and procedures. Dealing all the while with it's associated surprises and problems such as yours. Now-a-days I get paid to investigate and attempt to cure problems such as yours.

This one's a freebie.

This is the best I can do with the amount of information you supplied. My suggestion is a quick look at the problem that should only take about an hour or two of your time that will hopefully point to a solution.

You have not said what the terminating metalization on the capacitors is. I am assuming solder over nickel barrier.

On a component as small as 0603 gold embrittlement or other contaminant of the solder joint is a prime suspect.

Look closely at the capacitor you say you "popped off" with finger pressure, and the remaining solder on the board.

If solder remains on both, embrittlement is probable. Try a "quick and dirty " test (do this test with some solvent cleaned and some "out of the box" components, to determine if the supplied capacitors are contaminated in some way). Apply some solder to a few land patterns on a test board. Wick off the solder, thus removing the gold or other contaminant from the board and leaving the land tinned. Hand solder capacitors to these AND several other un-tinned lands. Try as best you can to simulate the production soldering conditions ie peak temp & dwell (if these tests yield no results, those factors will bear further looking into). Pop them off the way you did when first discovering the problem. If you see a dramatic difference, embrittlement or other contaminant is at work.

If the metalization has been removed from the end of the capacitor, or the solder remaining on the board shows the impression of the the capacitor terminations (indicating that the solder seperated cleanly from the capacitor)other than a "cold solder joint" (also determined by looking), the capacitor is the prime suspect. Investigate the metalization of that particular lot of capacitors on your own and with your vendor (Mfg.). Do some comparisons of other vendors products or implement component cleaning procedures prior to assembly.

This a "shooting from the hip" reaction to a line down problem. If it restores immediate production, take the time afterwards to refine the solution, improve economies, and QC monitoring (component qualification, incoming inspection, plating selection on the boards, solder selection, process controls, etc.)

I hope this has been some help! Good luck.

Jim Arnold

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#3077

Re: 0603 Components | 11 September, 2000

Adam: I would say that you do have a reliability problem.

- check parts for solderability - check your board finish - check your profiles - check your paste - check your processes with focus on cleanliness - do some mechanical tests, you should rather pull of the pads than damaging the joints - have your joints checked for the resulting structur, that might give more hints than any advice here.

Good luck

Wolfgang

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