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IPC-2581 is rapidly gaining support in the PCB design community as an "intelligent," vendor-neutral format that can bring design data into manufacturing in a single file. The PCB West conference in Santa Clara, California on Sept. 10, 2014 provided an update on this fast-moving standard and the IPC-2581 Consortium that is driving it.
The update was given by Hemant Shah, product marketing group director at Cadence and chair of the IPC-2581 Consortium. Shah talked about the rapidly growing consortium and the "unprecedented collaboration" behind it, the new features in the current RevB of the emerging standard, stackup exchange permitted by IPC-2581 RevB, and what it takes to join the consortium. He also cited ongoing standards work at Cisco System and Fujitsu Networks.
Here's some quick background. The venerable Gerber format (which goes back to the 1960s) can transfer image data to manufacturing, but it can't transfer stackup data, materials information, design intent, or netlists. As a result, PCB designers typically ship multiple files to fabrication and assembly houses, along with documentation explaining what it all means.
One attempt to create a more inclusive, intelligent format was ODB++ from Valor Computerized Systems, but with the 2010 acquisition of Valor by Mentor Graphics, that format came into ownership by Mentor. Thus, there is a renewed push behind IPC-2581—originally released in 2004 but not deployed—as a vendor-neutral data exchange format that will provide a single file for fabrication, assembly, and test.
A Growing Consortium
Last year at PCB West, Shah noted that 46 companies had joined the IPC-2581 Consortium. This year, that figure has grown to 61 companies, along with over 40 associate (individual) members. Company members include OEMs, PCB CAD providers, EMS (electronics manufacturing services) companies, and fabrication companies. Cadence took a leadership role in forming the consortium in 2011. Cadence competitor Zuken was one of the initial members, and Altium, also a competitor, recently joined.
In the first two years of the consortium, Shah noted, consortium members were going out and spreading the word about IPC-2581. During the past year, he said, more companies are coming to the consortium on their own initiative. That's because their customers are asking for IPC-2581 support.
The consortium has allowed PCB design and supply chain companies to work in "unprecedented collaboration," Shah said. When the consortium started, nobody was writing out IPC-2581, nobody was consuming it, and everybody was interpreting the standard differently. "One of the first things we had to do was to figure out a way to make sure that it's interpreted by Cadence in the same way it's interpreted by a consumer such as Adiva," he said. "So we created a technical group that created test cases we could share across the companies, to make sure the outputs were interpreted together."
Software was then made available to PCB design houses. Consortium members held three-way meetings, including a PCB CAD vendor, PCB design house, and EMS, to work through any problems that arose with the use of IPC-2581. Meeting participants identified areas in the spec that were ambiguous, and noted improvements that were needed to make the data handoff even more efficient.
A Fast Revision
Meanwhile, RevB was the fastest revision of a standard in IPC history, Shah said. The consortium went from a list of requirements in July 2012 to balloting and approval in August 2013. Major improvements included the following:
Another important RevB capability is stackup exchange. Today, as shown below, that exchange is done with emails, Excel spreadsheets, and screen shots. This is an error-prone, manual process that may lead to problems after the design goes to manufacturing.
Manual stackup exchange can lead to unpleasant surprises
With IPC-2581 RevB, users can output just the stackup from a fabrication tool or a CAD tool, and do an intelligent stackup exchange in which the data is directly consumed by the tools. (RevA had some stackup support but lacked the details to do this kind of automated exchange).
Automated stackup exchange avoids surprises and errors
Showing that IPC-2581 is real, Shah talked about the experiences of several consortium members. He noted that Cisco Systems has an internal team that is validating IPC-2581 output from layout tools. Cisco worked with Cadence to validate output from the Cadence Allegro PCB layout tools, and this work resulted in some changes to the specification. Further, Cisco has an internal stackup generator tool that is currently being updated to support IPC-2581 input and output.
Fujitsu Network Systems has successfully built baseboards using IPC-2581. The first board, a 12-layer plug-in optical module, was fabricated by CC Electronics (UK). A second board was built by Sanmina, Sierra Circuits, and TTM-OPC. All were successful with no iterations, Shah said.
The IPC-2581 Consortium is looking for more members. Shah noted that individuals can join with an associate membership. There's no cost—you just need to support IPC-2581 and allow the consortium to publish your name, current employer, and a brief statement of why you are joining the consortium. You will be invited (but not required) to participate in bi-weekly technical meetings and/or bi-weekly general meetings. See the IPC-2581 Consortium website for further information.
"It's very simple," Shah said. "If you want an open neutral global standard, join!"
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