Issue link: https://iconnect007.uberflip.com/i/1417991
OCTOBER 2021 I DESIGN007 MAGAZINE 43 e graphic-based Gerber file package is unintelligent and impossible to process auto- matically. A few of the serious limitations of Gerber are that a separate physical file is needed for each layer of PCB information (such as copper images, fabrication notes, assembly drawing layer etc.), the stackup exchange is via electronic paper, and it does not include drill information, which must be sent in a separate file and is oen mistakenly generated to a dif- ferent scale or offset than Gerber. In addition, Gerber-based packages contain no electrical connectivity information, so a separate netlist file must be sent for electrical bare board testing that may not match the Gerber pack- age. Finally, Gerber-based packages contain no component placement or bill of materials (BOM) information, so separate procurement files must be generated for those as well. Using legacy Gerber-based packages for manufacturing handoffs affects both the prod- uct development division and the manufac- turing division. For product development, experts are needed to ensure a successful handoff. On both the design and manufactur- ing sides, there are long process preparation cycles for DFM, design for assembly (DFA), and design for testability (DFT) review, pro- totyping, trials runs, etc., which increase com- munication issues between design and manu- facturing teams. e Gerber files and netlists don't always match. e problem has been compared to the subtle differences in lan- guages such as Spanish and Portuguese, which are almost the same, but not quite. In addition, the mechanical dimensions of the board in the fab document don't always match what is in the Gerber file. is unreliable process results in long pro- cessing times and inaccuracies that affect product quality and time to market. e pro- cesses are not repeatable because every com- pany has its own way of handing off that is not consistent. ODB++ and Other Formats Other formats used for the DFM handoff include GenCAD/FATF, an obsolete stan- dard no longer supported or maintained. e Centroid XY data format, used by some for its assembly information, contains efficient con- tent but can be out of sync with other data, which slows the handoff process. e ODB++ format is used by some designers, but it has compatibility risks over time, uses the same notes/instructions process as Gerber-based packages, doesn't provide stackup exchange, and, because it is a proprietary standard, users who are not customers or owners of the stan- dard may not get the support they need. Figure 2 compares these formats and their business impact. Figure 2: The business impact of various manufacturing handoff file formats.