I measured some tin/lead thickness on some 20 mil pitch pads (12 mil width, 8mil spacing) on some raw fabs and found the largest majority of the measurements to fall in the 450-600 microinch range (These measurements were made on a SFT 7455 X-ray fluorescence system.) However, there were a number of isolated pads with thicknesses exceeding 850 microinches which were were considerably more 'dome' shaped compared to those pads in the nominal 450-600 microinch range. SMT is decidedly having more problems (i.e., shorts) with the boards with the isolated 'thick' pads, but incoming QA says the boards are within spec. Can anyone share their experiences or data on an upper threshold thickness for tin/lead on 20 mil pitch boards? I'm not sure whether we have a part problem, process problem or both. Ed Tidwell DSC Analytical Lab [log in to unmask]