All solder joint goal default values for Toe, Heel and Sideare best industry guidelines derived from IPC-J-STD-001 Standard for AssemblyAcceptability. The calculator mathematical model for land pattern calculationis derived from IPC-7351, which uses the Terminal Lead Tolerance, aManufacturing Tolerance and the default Solder Joint Goals derived fromIPC-J-STD-001 (not IPC-7351). If you want to use the IPC-7351B solder jointgoals, then you should select the IPC-7351B_DefaultPreferences.dat Preferencefile and then save as your personal Preference file to edit all the DraftingOutlines, Rules and Pad Shapes. In the new upcoming V2020 of Library Expert, wewill drop the Manufacturing Tolerance to 0.00 as this only has a slight impacton the resulting pad size. But the user can add the Manufacturing Tolerance backif you want to use it. Also, all negative solder joint goals will be changed to0.00 as the negative values were created to compensate for the ManufacturingTolerance.

Note: The Library Expert default values have beenused to create millions of land patterns worldwide without any complaints fromany user. We believe that the values provide best industry practice for padsize and spacing calculations. However, every user, has the opportunity tochange any of the solder joint goal values for toe, heel and side, themanufacturing tolerances and the terminal lead tolerance to calculate a landpattern that best fits their unique assembly process. We urge all LibraryExpert users to consult with your assembly shop to evaluate all the numbersthat they need for the best package attachment to the PCB.