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64 DESIGN007 MAGAZINE I AUGUST 2020 ery clock doesn't start until the data package is complete and accepted. That five-day turn is sitting in the starting block waiting for the technical query (TQ) communication chan- nel to do its thing. The CAM engineer notifies the manager of the issue, and the front-end manager notifies the salesperson, who then informs their point of contact at the customer side. Then, that information is conveyed to the designer, and only at this point can the correc- tion and clarification process begin. All of this can easily take several days to resolve, so the designer pays for a five-day turn but gets the boards back in eight days. It's even more problematic if the fabricator misses a discrepancy in the data package and runs with the erroneous set. This raises a lot of questions, such as, "Which is the go-to file: the Gerber data, the drill file, or the netlist?" Do all your fabricators have the same understanding? Who is responsible for the scrap when that does happen? I believe the larger question should be, "Why would you ever leave the potential for that kind of discrepancy in your process?" Shaughnessy: How do Mentor's tools help designers provide solid data packages to their fabricators? McGoff: We understand that a PCB is a prod- uct, and we model it as such. The PCB is con- structed with specific materials, the features are attributed by purpose, and the manufac- turing process to be employed is understood. Properties like build-up layers in the design let the fabricator know the sequential lamination cycles that are needed. Test points are attrib- uted as test points and not merely as another round feature on the Gerber layer. This PCB product model is correct in design, validated in Valor DFM, and sent as a single container to the PCB fabricators. Shaughnessy: How does ODB++ figure into this equation? Do you have any numbers on potential hours saved per design, etc.? McGoff: Using ODB++ design data to transfer to fabrication eliminates the disparities found in legacy data sets. Everything the fabricators need can be found in this single, validated con- tainer: the board layers, drill data, and stackup information, for example. The ODB++ design format even supports the information usually found in the drawings, such as a reference to applicable specifications like IPC-6012A or the UL flammability rating. With all the information the fabricator needs in a single container that has been validated, there is no opportunity for discrepancies, mis- interpretations, or delays. One of our custom- ers, Optimum Design Associates, did a study a couple of years ago that showed using DFM and ODB++ can help reduce the TQs from their sup- pliers by 72%. That's what we call Lean NPI. Shaughnessy: It seems as if most fabricators are content to fix the bad or missing data, just to be sure they get the job. What do you think could be done to help change this situation? McGoff: It's an understatement to say that PCB fabrication is a competitive business. These companies are expected to be the lowest bid- der on a custom product with zero defects and to deliver as quickly as 24 hours. Because PCBs are often considered a commodity, the fabri- Patrick McGoff

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