In order to make up for the defect that Gerber, the traditional PCB data standard, cannot exchange data in two ways, three candidate formats of new PCB data standard are introduced: IPC’s GenCAM, Valor’s ODB + + and EIA’s EDIF400. The research progress of PCB design/manufacturing data exchange technology is analyzed. The key technology and standardization prospect of PCB data exchange are discussed. It is pointed out that the current point-to-point switching mode of PCB design and manufacture must be changed to a single ideal switching mode.

The introduction

For more than 20 years, the domestic and foreign electronic design/manufacturing industry is taking place by high-end Integrated Circuit (IC) chips, high-speed Printed Circuit Board (PCB), PCB) and Electronic Design AutomaTIon (EDA) technology. As a subsystem of electronic products, PCB plays the role of core module unit in electronic manufacturing industry. According to statistics, the design cycle of electronic products accounts for more than 60% of the whole development and production cycle; And 80% ~ 90% of the cost is determined in the design of the chip and PCB subsystem. PCB design/manufacturing data are generated by electronic designers using EDA tools, including fabricaTIon, assembly and test of PCB. PCB data Format standard is a descriptive language to regulate PCB layout design, which is used to realize data transfer between EDA tools or designers, data exchange between schematics and layout, and seamless connection between design and manufacturing test.

Gerber is the de facto PCB data industry standard and is still widely used. From the Gerber prototype in 1970 to the Gerber 274X in 1992, some information related to PCB processing and assembly cannot be expressed or included in Ger2ber format for increasingly complex designs, such as PCB board type, medium thickness and process parameters. Especially after the Gerber file is handed to the PCB processor, problems such as design rule conflict are often found through checking the light drawing effect. At this time, it is necessary to return to the design department to regenerate the Gerber file before PCB processing. This kind of rework takes up 30% of the development cycle, and the problem is that Gerber is a one-way data transfer, not a two-way data exchange. Gerber’s exit from the mainstream of PCB formats is a foregone conclusion, but it is not yet clear which will replace Gerber as the next-generation standard for PCB data.

A new PCB data exchange standard is being actively planned abroad, and the three recognized candidate formats are: The InsTItute for Packaging and Interconnect, IPC), Generic Computer Aided Manufacturing (GenCAM), Val2or’S ODB + + and Electronic Indus2tries AssociaTIon, EDIF400 EIA). The focus on standards comes as millions of dollars have been lost in recent years due to poor data exchange. It is reported that more than 3% of printed board processing costs are wasted each year on processing and validating data. In other words, billions of dollars are wasted on the entire electronics industry every year! In addition to the direct waste, repeated interactions between designers and manufacturers consume a lot of energy and time due to non-standard data. For low-margin electronics manufacturing, this is another invisible cost.

IPC GenCAM is a blueprint of PCB design/manufacturing data exchange standard developed by IPC, which is the ANSI accredited standardization research institute for PCB. The official document of GEN-CAM is named IPC-2511 and contains several sub-standards of the IPC-2510 series (IPC-2512 to IPC-2518). Ipc-2510 series standards are based on GenCAD format (introduced by Mitron), and the sub-standards are interdependent. The documentation of this standard includes the information of board type, pad, patch, insert, signal line, etc. Almost all PCB processing information can be obtained from GenCAM parameters.

GenCAM’s file structure gives both designers and manufacturing engineers access to the data. In the data output to the manufacturer, the data can also be extended, such as adding tolerances allowed by the processing process, giving multiple information for panel manufacturing, etc. GenCAM adopts ASC ⅱ format and supports 14 graphic symbols. GenCAM includes a total of 20 information sections detailing design requirements and manufacturing details. Each section expresses a function or an assignment. The MAssembly SMT knowledge class introduces professional SMT knowledge in colloquial language. Maxam Technology, the first PCB (MaxAM knowledge classroom) sample board, components procurement, and patch one-stop service provider! Each section is logically independent and can be used as a separate file. GenCAM’s 20 information sections are: Header, ordering information administratio, Primitives, graphics, layers, and welded blocks Stacks, Patterns, Packages, families, and devices. Devices, Mechani2Cals, Components, routes, Power, Testconnects, boards, Panels, FlxTUR Es), drawings and changes.

GenCAM allows the above 20 information sections to appear only once in the file, providing different information to the manufacturing process through changes in combination. GenCAM preserves the hierarchy and structure of information semantics, and each manufacturing device processes only the information section content relevant to its job.

Previous versions of GenCAM 2.0 files comply with bacos normal Form (BNF) rules. GenCAM 2.0 adopts the XML file format standard and XML scheme, but the fundamental information model in IPC-2511A has hardly changed. The new version only rewrote the organization of information, but the content of information has not changed.

At present, many CAM software vendors of EDA and PCB support GenCAM as data exchange format. These EDA companies include Mentor, Cadence, Zuken, OrCAD, PADS and Veribest. PCB CAM Software vendors include ACT, IGI, Mitron, RouterSolutions, Wise Software and GraphiCode, etc.

Valor ODB + + Open Data Base (ODB + +), launched by Israel Valor Computing Systems, allows design for Manufacturing (DFM) rules to be embodied in the design process. ODB + + uses extensible ASC ⅱ format to store all engineering data necessary for PCB manufacturing and assembly in a single database. A single database contains graphics, drilling information, wiring, components, netlists, specifications, drawings, engineering process definitions, reporting functions, ECO and DFM results, etc. Designers can update these databases during DFM design to identify potential layout and wiring problems prior to assembly.

ODB + + is a bidirectional format that allows data to be passed down and up. Once the design data is transferred to the PCB shop in ASC ⅱ form, the processor can carry out process operations such as etching compensation, panel imaging, output drilling, wiring and photography.

ODB + + adopts more intelligent explicit structure, specific measures are: (1) including impedance, gold-plated/non-gold-plated hole, specific hole connection plate layer and other system attributes; (2) Use WYSIWYG to eliminate ambiguous information description; ③ The attributes of all objects are at the single feature level; ④ Unique plate layer and sequence definition; Accurate device packaging and pin modeling; ⑥ Support the embedding of BOM data.

ODB + + uses a standard file structure that represents a design as a file path tree, with a series of subfolders containing related design information under the design folder. The path tree can be migrated between different systems without losing data. This tree structure allows some data in the design to be read and written individually without reading and writing the entire large file, as opposed to a single large file. The 13 layers of ODB ++ file path tree are steps, matrix, symbols, Stackups, Work Forms, and Work Flows, Attributes, Aperture tables, input, output, user, extension, log, etc.

A normal ODB + + design can contain up to 53 design files in the above folder, plus 2 more files in the ODB + + library design. ODB + + supports a total of 26 standard graphic symbols.

Because of the particularity of PCB design, some large files in database are not suitable for structured storage. For this purpose, ODB + + uses a file style of recording text in lines, each line containing multiple bits of information separated by Spaces. The order of lines in a file is important, and a particular line can require that subsequent lines follow a certain order form. The character at the beginning of each line defines the type of information that the line describes.

Valor was released to the public in 1997. In 2000, ODB + + (X) 1.0 supported XML standard was released. ODB + + (X) 3.1A was released in 2001. ODB + + (X) rewrites the information organization of ODB + + in order to facilitate the data exchange between design and manufacturing, while its information model does not change much. An ODB + + (X) file contains six large child elements, That is, content (ODX-contents), Bill of Materials (ODX-BOM), Authorized vendor (ODX-AVL), Auxiliary design (ODX-CAD), supply information (ODX-Logistics -HEADER) and change (ODX-HistoryREC), etc. To form a high-level element (ODX).

EDA software vendors such as Cadence, Mentor, PADS, VeriBest and Zuken, among others, have begun to support ODB + + / ODB + + (X). PCB CAM software vendors such as Mitron, FABmaster, Unicam and Graphic have also adopted ODB + + technology. Among these software companies, Valor user alliance is formed. As long as EDA data is exchanged and neutral files are processed, device drivers and detection programs can be formed.

EIA EDIF400 Electronic Design InterchangeFormat (EDIF) was developed and published by EIA.It is actually a modeling language description scheme. EDIF is a structured ASC ⅱ text file with BNF description mode. Versions of EDIF300 and later use the EXPRESS3 information modeling language. EDIF300 describes information including hierarchy information, connectivity information, library information, graphic information, instantiable object information, design management information, module behavior information, simulation information and annotation information.