Regarding HASL thickness, here are the parameters that
          my company adheres to.  All measurements are taken at the
          geometric pad center.  We read every 50th panel coming off
          of our horizontal leveller.  Horizontal levelling helps to
          more evenly disperse the solder and fights a pronounced
          "north-south-east-west bias" on QFP's.  The boards enter the
          solder pot horizontally cocked at 45 degrees.
               .025" pitch or less = .00008" - .001"
               .050" pitch = .00007" - .001"
               discretes = .00005" - .001"
          This shows that solder thickness is dependent upon pad
          geometry; i.e., the greater the area for the solder to
          retreat onto, the thinner the solder tends to be.  I should
          add that in all cases, HADCO guarantees solderability.
               Concerning scoring, make sure that your fabricator does
          simultaneous scoring (V-grooves from both sides at the same
          time), and not flip scoring.  I say this because boards have
          a thickness tolerance, .062" (+/-.007") for instance.  This
          means that the end user will accept a .055" thick board, a
          .069" thick board, or anything inbetween.  Spec out your
          remaining board thickness after scoring and this will
          prohibit flip scoring.  Here are the parameters that we
          recommend:
               .062" thk bds. = .012" (+/-.002") remaining thickness
               .031" or less = .010" (+/-.002") remaining thickness
          Of course, depending upon the components used, you may have
          to adjust this (i.e., heavy components may cause you to beef
          up the remaining thickness by .002" or so).  Most end users
          are now using some sort of fixturing when depanelizing
          scored boards.  This helps eliminate cracking peripheral
          capicitors and such.
          Regards,
          Tom Coyle
          Field Services Engineer
          HADCO Corporation