IPC782 and SMT Plus pattern libraries| 8 April, 1999
FYI, Yes, it is true SMT Plus [ http://www.smtplus.com/ ]does not meet IPC 782 standards but is that the goal here or to meet IPC-A-610 standards for manufacturing? I agree that patterns do cause some problems if created to maximum IPC standards but not when made to the IPC782 minimums. We are presently looking at buying SMT Plus libraries. Our manufacture has indicated problems using these smaller size patterns. We currently design all our boards using minimum standard patterns from IPC782 and are finding that we can not compete our competitors with regards to density. We also are pushing the limit for ICT testability using .025 pads on .050 - .075 centers with spacing at least .036 from component bodies. Clamshells are becoming more and more common and expensive. We use the same SMT lines for production and prototypes and need to use patterns that meet IPC-A-610 standards for production. Anyway we have taking the action item to introduce several cards with these smaller patterns and send them through manufacturing. Well to our delight we have 100% testability and no known issue from the SMT lines. With this in hand we worked with our manufactures and we agreed these smaller patterns are fine for production and will start to use several in our new pattern libraries for production shortly. These patterns outlines are to the device manufactures maximum body as well. This is one of my concerns regarding Mr. Blackenhorn pattern. With densely packed card using patterns made to smaller than manufactures guidelines we may encounter problem during ICT. What about differences from supplier to supplier. Jim answer was that the part come in a specific size and he makes the part to that standard size. These are always smaller than the IPC and manufacturers standards and make me uncomfortable. Now we need to ensure the patterns sizes for alternate part for production come it at specific sizes too. IPC make all of this easy and this seems to be ground some of use can not afford to swim in without further research. I have spoken to Mr. Blackenhorn and found his arguments are sound but can't confirm the reliability with our limited research. We are looking at buying these CD's but need more evidence before we start using them in our production designs. I'm interested in others success stories using these patterns and what yields they are experiencing. We also need to know of any bad experience others can share as well. Both are equally important to our efforts to move forward. Please contact me through the forum or email or call off line to discuss further. I would appreciate any and all input.