Hi  Everyone,

I'm new to the Technetters.  I have been a Trainernet for just a short time and have discovered that I also need you as well.

So here goes.

Problem: We ( TRMI ) are periodically experiencing horns on a 
 screw head. After wave solder process.

Information:  
Screw:               Tin plated 
Flux:                   Christopher JF900 2LF
Solder:                Alpha Metals 63%  37%
Process Profile:  Not changed

Self Tapping screw is securing a 4 terminal connector to the PCB. 
 Design indicated this type of screw is to be used to ensure proper 
 torque setting of screw in  finished product.  
 Covering the screw is not an option. Designer has a plating  
 around the screw to aid soldering process.

Questions:
 1) Could Nitrogen be a factor in creating horns during the 
       wave solder process.
  2) Could Nitrogen place a part with other defects as bridges
        and missing solder
  Japan and USA make the same product.  Japan does not have 
 this problem.  Difference in process is Nitrogen.  
   3) Any ideas  on why we get horns. 

Thank you for your time
Nancy

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