There are a number of published papers on the subject -- suggest you do a literature search. No-clean assembly may require tighter process controls and possibly changing to an OSP compatible no-clean flux. I would also recommend working with your PCB shop/OSP supplier to address specific issues. I found our OSP supplier very helpful for providing support on assembly-related technical "roadblocks". Dave Boggs Merix Corporation phone: (503) 359-9300 fax: (503) 359-1181 [log in to unmask] Wrote: | | | I would greatly appreciate any input regarding changing from | HASL to OSP. We assemble heavy copper boards and are | experiencing difficulties as we move to 0805 chip packages. | We | are comtemplating changing to OSP to alleviate some of the | pain. I would appreciate any info regarding process changes | we | may have to make (pad design, pre-heat, flux application | method, etc). A typical application is 4 layer board with 2 | oz. internals and 2 oz. externals plated to 3 oz. Three | thermal cycles (top side reflow, bottom side epoxy cure, and | wave solder). SOIC and SOT-23 on top, 0805 on bottom, plus | through hole components. No-clean paste and wave solder | flux, | wave flux applied by foaming on most machines but spray | fluxer | also available. Assemblies have high thermal mass (large | magnetics and heatsinks). Thanks for your help. | | Pat Bailey | Zytec Corporation | phone 507 637-2966 x355 | fax 507 644-3720 | e-mail [log in to unmask] |