Fred,

The following is my opinion on the term resin recession.  IMO resin 
recession is a poor term.  It infers that the resin has backed away 
fron the hole wall.

When going past the Tg temperature (130 degrees C in most cases), the 
board material becomes very soft.  As the temperature rises, the 
material becomes more flexible.  At soldering temperatures, it  
becomes extremely rubbery.  When you float the sample for testing, 
the temperature is generally 500 F.  The epoxy in the laminate 
material, adjacent to the copper hole wall, becomes extremely hot.  
IMO the area you are calling resin recession, is nothing more than a 
heavy concentration of epoxy caused by the extreme heat next to the 
hole wall.  Remember, with two solder floats, this is the third time 
the board saw extreme heat due to a necessary HASL operation. 

 I beleive that the only problem here is that you can no longer see 
the glass fibers adjacent to the hole wall due to the epoxy becoming 
semi-molten during the extreme heat requirements.  I believe that the 
hole structure has not changed but only the semi-molten epoxy changed 
the appearance.

You may see this same problem after the HASL process only, and 
without your solder float test.  I'm sure that you would not have 
seen the same problem BEFORE the board ever experienced any heat.  
IMO there is absolutely nothing wrong with resin recession!

Regards,

Norm Einarson
Printed Circuit Technology