James, You are correct to assume that the members of the committee included idividuals from most product categories. The participants are listed inside the front cover of the standard. I also have listened to those same arguments, which are valid issues. The first thing that must be understood are the rules that the committee had to meet. Most designers today do not know what soldering process will be chosen for a particular assembly. If the soldering process is at a captive facility, then the decision is relatively simple. However, many products are outsourced, making the designer's choices very difficult. Therefore, the committee was tasked to recommend land pattern design principles that are process independent. The result is land patterns that may just be larger than those used in a captive assembly facility. The product may not pass through the soldering line as fast as the assembler wishes, but the result WILL be high yield and high reliability. The second thing to recognize is that the formulae ask for specific information about component sizes, tolerances, fabrication allowance and assembly accuracy. The user may input any numbers they choose. I'm positive that when your manufacturing people provided their input to the land patterns, you design, they took license to certain criteria. It's possible that they purchase tightly controlled components that never exhibit the tolerance extents shown on an EIA specification drawing. Therefore, they use a reduced number in their calculations. Maybe the pick and place accuracy is better than what the industry considers normal. These are just a couple of examples that would tend to reduce the size of a land pattern. The original IPC-SM-782 gave recommendations, for specific families of components. The user community requested that the principles be specified so that they may apply them to new components that are introduced. There were others that still wanted to know what the rest of the industry was recommending. Therefore, the IPC-SM-782A contains the formulas, explanations, and anaysis for the components that were available at it's writing and the tables with industry assumptions and recommendations. Lastly, you will find that if the same assumptions were applied to the formulae, as were applied to the home grown land pattern, the resulting land pattern sizes would probably be very close to the IPC landpattern. Most of the feedback has been positive, with size being the number one complaint. Very few, if any, complaints about yield or reliability. Regards, Gary Ferrari IPC Staff *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************