Once the wave soldering process is optimized (DoE), then the SPC plan should 
monitor the critical parameters.  You might try generating control charts for 
things like preheat temperatures, conveyer speed, flux density, solder 
temperature, etc.  The SPC philosophy is that once these critical parameters 
are in control, your process is in control.  

Monitoring solder defects is a way of determining how well your SPC plan works.  
This also will shed some light on what external factors affect (or effect?) 
your process like solderability, environmental conditions, etc.  What we do is 
inspect the first piece of every lot (or run) and plot % defects based on the 
number of soldering defect opportunities... usually the number of PTHs.

Hope this helps... 

Jim Marsico
(516) 595-5879
[log in to unmask]
		
              ********************************
	      *	      ______   _   _  _____  *
	      *	     / ___  | | | | | _____  *
   	      *	    / /___| | | | | | _____  *
	      *	 __/  ____  | | | | |______  * 
	      * |____/    |_| |_| |________| *
	      *				     *
	      *	        SYSTEMS, INC.	     *
	      ********************************				       


***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to:           *
* [log in to unmask] with <subject: unsubscribe> and no text.        *
***************************************************************************