Equipping the PCB Design and Supply Chain with 21st Century Data Print E-mail
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Written by Keith Felton and Hemant Shah   
Thursday, 28 July 2011 15:36
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Equipping the PCB Design and Supply Chain with 21st Century Data
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A new, broad industry consortium drives for standardization across design, fabrication, assembly and test.

PCBs have changed significantly over the past three decades, yet to the surprise of many, we still commonly use 30-year-old ways of communicating design intent to manufacturing. These decades’ old data-communication formats were originally conceived to drive the emerging numerically controlled machines. Adoption of these formats was further driven by the growth of computer-aided design tools in the early 1980s and the need to move from reprographic photography artwork to digital data-driven manufacturing.

Many formats were created by hardware manufacturers themselves, or derived from broader standards, and over time became commonplace. Such numerically controlled equipment included photoplotters, drill/mill machines, assembly (insertion/pick-and-place), test, etc. The Gerber Scientific Corp., a photoplotter hardware manufacturer, created one of the industry’s best-known de facto standards, Gerber RS-274-D, which later evolved into RS-274X.1 But Gerber data alone were not enough to produce a completed PCB assembly, so other data formats were created, again to drive specific numerically controlled manufacturing equipment.

Using multiple formats to fabricate, assemble and test a PCB is fraught with issues. For starters, there are data inconsistencies caused by the CAD software when producing all the different file formats, especially when data files are not from the same revision of a PCB design. Most formats in use today were designed to drive machines, not to provide a complete relational view of the design data. Over the past three decades, this has been compounded by the evolution of PCB design, manufacturing and test capabilities. Consider just a few of the technology advances since the humble Gerber came about: surface mount components, JTAG test circuits, BGAs, blind and buried vias, microvias, buildup layers, embedded components (discrete and active), and embedded waveguides. The list will continue to grow as designers struggle to address consumer desires for more (functionality, reliability) from less (size, power, weight, cost, etc.).

IPC, the trade group, has been aware of the challenges and dynamics of the PCB design and manufacturing segment and has been an ardent advocate for the replacement of Gerber for more than 30 years. Over that time, IPC has defined and published multiple data format specifications that vied to streamline the process of transferring data from design tools to numerically controlled manufacturing and test equipment. In the late 1990s, it began looking at a single open, nonproprietary, holistic definition for printed board manufacturing, assembly, inspection and testing. That project was known as “Generic Requirements for Implementation of Product Manufacturing Description Data and Transfer Methodology” or GenCAM.

GenCAM, which under the IPC taxonomy is also known as IPC-2511, was first published in early 2000. It was a revolutionary step beyond Gerber, and, as such, was a stretch for many to adopt. Instead, companies in the PCB supply chain took a passive approach to adoption, waiting for others to take the lead, while continuing to use Gerber despite the known costs incurred from its inadequacies.

In early 2001, iNEMI (the International National Electronics Manufacturing Initiative) stepped in to lead a broad, industry-wide project to define the definitive data exchange convergence specification. The goal was to enable accurate, efficient data exchange between designers and manufacturers of printed circuit boards (PCB) and assemblies using a single XLM-based data exchange format. From this effort, an IPC committee developed a new standard, IPC-2581, Generic Requirements for Printed Board Assembly Products Manufacturing Description Data and Transfer Methodology; it was released in March 2004.

A New Consortium

With IPC-2581, the industry finally has a global opportunity to replace Gerber and save millions of dollars wasted by its inadequacies. But as usual with data format specifications, nothing can be done until the supply chain produces, consumes and supports such a specification. This is where a new consortium of PCB design software (EDA) and supply chain companies fits in: to bring companies together to enable, facilitate and drive use of IPC-2581. The charter is simple: “To accelerate the adoption of IPC-2581 as an open, neutrally maintained global standard to encourage innovation, improve efficiency and reduce costs. The members of the consortium will openly support and promote the adoption and usage of IPC-2581 by enabling their products, offerings and services to import/export/consume IPC-2581.”


Last Updated on Wednesday, 10 August 2011 14:26
 

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