SMT resistor not wetting - Have you seen this before?

W

William Gr

#1
This is a new on for me (see photo) and I have been doing this for 20 years.
There are 20 of these resistors placed on the board.
This is the only one that did not wet. That rules out contamination.
The solder under the part reflowed just fine, so it is not a heating issue.

Any ideas? :confused:
 

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e006823

#2
Re: Have you seen this before - SMT resistor not wetting

What about contamination on the component terminations or uneven flux application?
 

somashekar

Staff member
Super Moderator
#4
This is a new on for me (see photo) and I have been doing this for 20 years.
There are 20 of these resistors placed on the board.
This is the only one that did not wet. That rules out contamination.
The solder under the part reflowed just fine, so it is not a heating issue.

Any ideas? :confused:
Just one questions ..
1. Is it just in one board ?
 
W

William Gr

#5
Thanks for the reply.

It only occured on one board out of 4000.
Since all other 80,000 resistors soldered OK, and this one resistor did not. I ruled out contamination. Unless someone else has seen one part on a reel of 4000pcs be contaminated.
 

somashekar

Staff member
Super Moderator
#6
Thanks for the reply.

It only occured on one board out of 4000.
Since all other 80,000 resistors soldered OK, and this one resistor did not. I ruled out contamination. Unless someone else has seen one part on a reel of 4000pcs be contaminated.
It will be good to conduct a solderability test on that lifted component and compare same with other components of the same pack. Some local contamination might have happened during the take-up process in the reel or during the pick and place process.
 
W

w_grunfeld

#7
Since it's only 12.5 ppm I wouldn't worry too much whatever the elusive root cause is.
 
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