We have been encountering diminishing ball shear readings these past few weeks, despite the fact that we did not change any ball shear tester parameter. Our reflow parameters are also within spec limits. ( 210-220 deg C max temp. and 40-60 sec dwell time ) Beforehand we use to clean the substrates with water (from defluxer), but now we returned to the old procedure of cleaning with acetone. This has promted me to suspect that acetone , someway or the other, effects solderability/wetting. Can I ask your help in the analysis of solder land before and after acetone cleaning ?.