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Power Management IC - Assembly issues

JimQQ

Apr 18, 2024
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I use Nordic nPM1100 (BGA package) as power management at PCB boards, combining it with 3.7V Li-po batteries and unfortunatelly the malfunctions are very common. Short circuits are created very easily after hours of board's operation or affects the correct operation of other circuit's components. I suspect that the problem lies in its soldering, as its small size (2mm X 2mm) with many pins (25) makes it very difficult to solder it correctly.

Has anyone else used the same Power Management from Nordic before and faced the same problems?
If no, do you have any idea what can solve this problem?

Thank you
 

Delta Prime

Jul 29, 2020
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I suspect that the problem lies in its soldering, as its small size (2mm X 2mm) with many pins (25) makes it very difficult to solder it correctly.
Ball Grid Arrays do not develop shorts over time in the manufacturing process (shorts) bridges occur when extra solder paste is left between paste deposits. Bridges between connection points often result in shorts.
By the time it gets to you it goes through quality control and are thoroughly tested. The only way one can determine for certain if shorts, Bridges are created is for QC uses x-rays to view through the component itself and see solder connections
Only signing off on that particular PCB in the manufacturing process before it goes to calibration on the assembly line.
 

JimQQ

Apr 18, 2024
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Ball Grid Arrays do not develop shorts over time in the manufacturing process (shorts) bridges occur when extra solder paste is left between paste deposits. Bridges between connection points often result in shorts.
By the time it gets to you it goes through quality control and are thoroughly tested. The only way one can determine for certain if shorts, Bridges are created is for QC uses x-rays to view through the component itself and see solder connections
Only signing off on that particular PCB in the manufacturing process before it goes to calibration on the assembly line.
Thank you Delta Prime for your reply!

I have already used X-rays to see solder connections of the component and everything was ok.

To be more specific, the short circuits appeared at many points on the board after hours of operation, without knowing what's wrong. For this reason, I disassembled various parts on the board and the problem was solved when I desoldered the Power Management.
 

Delta Prime

Jul 29, 2020
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Your board may suffer from whiskers.
Excellent point. But one must acknowledge that tin whiskers cannot be stopped until we understand how they form in the first place.
With that said "Empirically" the thread starter had heated up the component to reflow the solder.
Giving credence to the fact that it may very well be tin whiskers. I'm just happy that my unit that I've used for 2 years has not suffered the same fate. ;)
 

JimQQ

Apr 18, 2024
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Thank you for the advice, I didn't know anything about this tin whiskers phenomenon. I made a research and I found out that tin whiskers need time to grow in contitions with enough temperature and humidity.
Since I faced this issue on the Power Manager within a few days after boards assembly, does it make sense that tin whiskers have had time to be created and caused that problem?
Also, can the whiskers be created during board's assembly through the machine that places the components?
 

Harald Kapp

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Nov 17, 2011
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does it make sense that tin whiskers have had time to be created and caused that problem?
The groth rate of whiskers depends on the environment (temperature, humidity, ...). If there are whiskers, you can see them with a bit of magnification.
can the whiskers be created during board's assembly through the machine that places the components?
To my knowledge: no.
 

Delta Prime

Jul 29, 2020
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I made a research and I found out that tin whiskers need time to grow in contitions with enough temperature and humidity
Also altitude, along with combinations of various alloys to suppress said whiskers but to no avail.Excellent subject for research and experimentation especially if you're into metallurgy.
Since I faced this issue on the Power Manager within a few days after boards assembly
I would look into the type of solder you're company purchased. If you notice this right after the production your either going to get a pat on the back & a 5 cent raise or you are going to be labeled a troublemaker.
 
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