Issue link: https://iconnect007.uberflip.com/i/1401769
AUGUST 2021 I PCB007 MAGAZINE 13 everything. It doesn't ex- ist out there. I worked with a large CAD soware compa- ny and I said, "Here are the design rules for routed edge trace and scored edge trace to punched edge." ey're going, "We only have trace to edge." ose three profiling meth- ods may have different rules, but they can't even check it. Probably about half of the rules that I went through with them don't exist. Holden: And that technology can change so rapidly in so many different directions. e only place where it comes together is at the fabricator. Korf: Each fabricator can have a different set of rules based on how their factory process is and the rules that govern it. One OEM challenge is how to integrate the multiple sets of rules into a common set for the designer. Holden: And each OEM is pushing for some direction other than what another OEM is. And fortunately, the assembly industry is di- verse enough to have specialists, but the fab- ricators, through consolidation, come togeth- er in a much smaller group of people. Espe- cially in prototype, we're down to 290 facilities in North America from what used to be 3,000, and those 290 have to do more variety to han- dle the increasing number of OEMs, and the permutations and combinations that come to- gether. And no DFM soware or sets of ERFs can cover all the different ones. It still comes back to that CAM engineer. Thompson: CAM operators are very literal peo- ple. So don't induce rounding errors by mix- ing Imperial versus metric. If you're exporting your drill format as 2:4 trailing, and you output your Gerber 2:6 leading, it takes a little while for the CAM operator to fish through those things and fig- ure out what is the actual for- mat to be able to place that data. Additionally, there are those discrepancies, those rounding errors, that happen for drawings. For instance, if you call out an eight-mil line for 50 ohms, and you actual- ly output it as 0.2 millimeters, and it's true, it's 0.0078." So what is that 0.0002" going to do to the impedance? Proba- bly nothing. But as a very literal person, such as a CAM operator, they're going to look at it and say, "ere aren't any eight-mil traces." en they're going to make a phone call, and it's going to waste time. Holden: e thing I used to love the most was in China reading all the manufacturing instruc- tions that are in English, and the CAM engi- neer is constantly asking you what this means because people weren't using proper English. ey're using slang or undefined terms that hadn't been defined by the IPC yet. I was try- ing to emphasize to everybody that, although you understand the English, to get it translated into Chinese, it may not be the same. But if you translated English into German or Russian, it will have exactly the same meaning. Korf: I worked in China for many years, where front-end engineers are working in non-native languages. For example, you have an engineer in France whose native language is French. He translates the TQ question or note into what- ever version of English he learned—whether the queen's English, American English, South- ern English, a French version of English. A Chinese engineer then interprets the note in the version of English that they learned and then into Chinese. Sometimes a planner would bring me a note from a customer, and it was in English. I'd read it and say, "I have no clue Mark Thompson