Address,
     
     I have a recent lot (100 pieces) of assemblies with enough warp in the 
     longest edge to keep the assembly from plugging into the backplane.  
     As a flag, the warp should have been caught by operators following 
     Wave, but was not.  I have a solution to ensure future assemblies are 
     not affected.  I am also in the process of modifying the Wave fixture 
     for low mass assemblies and the Wave Process Flow Procedures.
     
     There are three options I have come up with to (temporarily) fix the 
     warp problem, such that the field engineers can insert the assemblies.
     
     OPTIONS:
     1. Bake assemblies in oven at X temperature for X time with applied    
        weight; or 
     2. With the modified wave fixture, which ensures rigid stability in    
        all regions, re-solder assemblies via wave soldering; or
     3. Run assemblies through the Convection Reflow Oven at X temp for X   
        time with the modified fixture holding the assembly in place
     
     I have opted to go with Option 3 and would like to hear others 
     experience(s) or any other avenues of thought.  I am thinking the 
     assemblies shall be run at a maximum of 220°C for 55secs max. (ramp up 
     temp/time is not included) at 1.12cm/sec using a Heller 1500 Reflow 
     Oven.  My insanity is to bring the fab temperature as close to the 
     fabs Tg to minimize if not eliminate any Warp Memory.  Granted, this 
     is another thermal excursion, but lets approach as if there are no 
     alternatives and components can withstand.
     
     Thank you
     
     John Gulley 
     Inet Inc.
     Plano, TX 75075
     972-578-3928

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