In the near future, there is a proposal to develop new solder joint goal rules using the pin pitch and terminal height for pad calculations. You think the IPC-7351C 3-Tier system is complex? Wait for the new J-STD-001 / IPC-610 land pattern standard for SMD proportional pad stacks. I can't mention much of this new standard, but it will be in the Library Expert Pro as an alternative calculator in our V2016 release. I personally believe the new SMD proportional standard will eventually replace the 3-Teir system with one golden pattern for all density levels and fabrication classes. It's different strokes for different folks. Examples: I worked at Applied Medical Resources (AMR) and they used an AMR part number for every mfr. part number. They had 3,000 ARM part numbers for just resistors and capacitors. The AMR part number was the footprint name and went into the schematic symbol that way. Honeywell has 100,000 mfr. part numbers in their library and they assign a Honeywell part number to every mfr. part number just like AMR however, they use the IPC-7351 land pattern naming convention for most of their footprint names. Flextronics has over 2 million mfr. part numbers in their library, each with a unique footprint. I'm trying to give you the BIG picture where mfr. part numbers each have a unique set of package dimensions and tolerances and the footprint is unique for each package. It seems like a lot of work, but PCB Libraries, Inc. will soon be providing a global solution that will dramatically simplify this task of organizing and maintaining large libraries. It was mentioned that "What if my component goes obsolete and I need to find a replacement that fits the footprint". Well, I hope there's not to many PCB's in stock because the obsolete part needs to be designed out of the project and replaced with new Gerber's for new boards. In the meantime I hope you find a suitable replacement. If you used "Silicon Expert" to source your parts, they would alert you to upcoming obsolescence a year in advance and recommend alternate sources. If your company requires 2 or 3 sources for a single footprint, find 3 packages that have very similar package dimensions and tolerances and disqualify all manufacturer's that produce unique packages. Component manufacturer's are doing their best to create unique packages to corner the market into single sourcing their package. Get used to it, this is a trend that is growing at a rapid pace. For those who want to take short cuts and use 1 pattern for every 1206 chip capacitor, resistor and inductor in the industry, I wish you the best of luck with that option. It might work most of the time. But if you do 3D STEP modeling, you're going to need several options due to height.
------------- Stay connected - follow us! https://twitter.com/PCBLibraries" rel="nofollow - X - http://www.linkedin.com/company/pcb-libraries-inc-/" rel="nofollow - LinkedIn
|