Electronic Design

Consortium Drives Open PCB Design-Data Standard

The IPC-2581 Consortium, an industry group aimed at promoting adoption of the IPC-2581 standard for transfer of printed-circuit-board (PCB) design data, seems to be gaining momentum with the addition of ScanCAD International, Ucamco (formerly Barco ETS), and Aegis Software as new members. Spearheaded by Cadence Design Systems, the IPC-2581 group spans EDA vendors, CAD/CAM houses, OEMs, and contract manufacturers, all of whom the group claims stand to benefit from an open standard for transfer of PCB design data (see the figure).

The consortium formed in late July, went public with its mission in early August, and had a coming-out party of sorts at last week’s PCB West conference in Santa Clara. At that conference, attendees witnessed a demo in which PCB data was transferred between tools from Cadence and Zuken without a glitch.

The demo used data for a golden-reference board developed by Fujitsu Network Communications (another consortium member). In the demo, data was output in IPC-2581 format by Cadence’s Allegro PCB Designer and read in by Zuken’s CR-5000 suite. “We demonstrated this in an engineering-change-order (ECO) type of activity to show the tools’ ability to detect changes between two iterations of a design,” says Gary Carter, senior manager for CAD engineering at Fujitsu Network Communications. “We have interest in leveraging this capability during definition of our board stack up, so we’re working with suppliers to bring them over from legacy formats.”

What’s behind the sudden interest in IPC-2581, a design-data transfer format that’s been around since 2004 and a standard since 2005 but had largely been ignored? For one thing, the tried-but-true Gerber format for design data still works, but it is quite outdated. Properly implemented, Gerber is perfectly adequate to transfer image data, but it does not transfer board stackup data, materials, design intent, or netlist.

A more recent alternative to Gerber is the ODB++ format pioneered by Valor Computerized Systems. But when Valor was acquired by Mentor Graphics early in 2010, some quarters of the PCB industry became wary. “ODB++ is a widely used format used by many of our customers and Cadence’s customers,” says Steve Chidester, head of product marketing at Zuken. “Valor controlled ODB++ fairly tightly, but as long as they were independent, that’s worked well enough. But with it coming under Mentor’s control, their non-customers are nervous about it. History shows when a vendor controls something they use it to their advantage.”

For its part, Mentor Graphics rejects the notion that its stewardship of ODB++ is anything less than benign. “We’ve all been working to solve the same problems, to find a way to give PCB designers a cleaner, faster output to manufacturing that speeds design time and minimizes risk,” says David Wiens, business development manager for Mentor’s Systems Design Division. “We also want to solve the same problem on the manufacturing side; those are the guys that have to prep the design. That process can introduce quality issues and impact cost.”

With its acquisition of Valor and ODB++, Mentor inherited stewardship of an existing ecosystem that surrounds ODB++ and is not likely to abandon support of customers that are invested in that ecosystem. “It would run counter to logic to say that we would retire ODB++,” says Wiens. Mentor has no plans at present to support the IPC-2581 format, but Wiens says, “if our major customers came to us and asked us to support IPC-2581, guess what would happen? We want to solve the problem and not get into a format war.”

It’s worth pointing out that the IPC-2581 standard in part owes its existence to Valor’s technology donation of ODB++. Both formats have evolved since then, but none of the parties in the ensuing debate can categorically state that one is technically superior to the other. “The relationship between the formats is very close because IPC-2581 is based on the public domain version of ODB++,” says Humair Mandavia, senior product marketing manager at Zuken. “New enhancements to both formats are continuing, so there are probably some differences. But we are not aware of any significant gaps between the two.”

Mandavia opined that users are not fully sold on ODB++’s ability to replace the venerable Gerber format. “In our conversations with attendees at the PCB Design Conference, they tell us they still find it necessary to provide Gerber and NC drill data whenever they send ODB++ to a manufacturer. This is because it is the only method for validating both sets of data. Gerber has one common flavor, which is RS274X; ODB++ translation can be of different versions or contain key words that may not be interpreted by manufacturers in the same way.”

Nevertheless, the IPC-2581 Consortium’s goal is to rally behind an open format that would seem more resistant to any one entity’s influence. “Our motivation was to have a more intelligent way to produce design data without so many variables,” says Hemant Shah, director of product marketing for silicon realization at Cadence. “We wanted a more intelligent data-export format that eliminates a lot of extra drawings and spreadsheets outside of the central format that we’ve historically provided.”

Cadence will provide support for IPC-2581-formatted data output with the next release of the Allegro PCB Designer suite. Support in the OrCAD PCB Designer is pending. For Zuken, support is already built into its flagship CR-5000 PCB design suite, with support in the CADstar tool coming later.

IPC-2581 Consortium
www.ipc2581.com

Cadence Design Systems
www.cadence.com

Mentor Graphics
www.mentor.com

Zuken
www.zuken.com

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