Hi Gebhard, Mr. Zuverlässigkeit is here; Lee gave an excellent answer, so I did not see the need for my 5-cents. At this moment, you have stomped my with IPC White Paper called "Design for Success"—when and where was it published? And I do not see the need to specify a maximum barrel wall thickness, 38 [µm] or otherwise. Typically copper thicknesses are too low. In order to get knee/corner/shoulder cracks you need a large amount of land rotation; if you have large plating thickness in the PTH you also have a great Cu thickness at the surface pad—this would resist land rotation. Now, if you prevent plating on the surface, then...yes Just like Lee, I have seen PCB reliability to suffer with the higher LF soldering temperatrures and the demand on PCB quality [drilling, Cu plating uniformity, copper plating ductility, adequate copper thickness (1 mil or better yet 1.2 mil)] go up. That is why I have written my White Paper "Recommendations for PCB FAB Notes and Specifications in Printed Circuit Board Drawings for SnPb and Lead-Free Soldering Assemblies, the Qualification of PCB Shops and Activities to Assure Continued Quality." Werner ************************************** Get a sneak peek of the all-new AOL at http://discover.aol.com/memed/aolcom30tour