Issue link: https://iconnect007.uberflip.com/i/1276973
AUGUST 2020 I DESIGN007 MAGAZINE 17 difference between a quick turn local PC shop and high-volume offshore company in terms of the difference of materials and the pain that it caused depending on how sensitive the board is. I don't have any notes of any partic- ular references other than, eventually, you'll get around to hole plugging, which has always been a headache from a notes point of view. I always tell people, "Just steal the picture out of the IPC standard and paste that on the drawing so that we can see what it is. Don't make up new words." Especially if you're going to go to Asia, I remind people that English is usually not their native language. A lot of these made-up words that we use to describe PCBs don't translate well into Chi- nese or other languages. It's a source of mis- understanding and error. Shaughnessy: What do you think is one of the biggest mistakes that designers make, and what advice would you give for correcting them? Korf: From a notes standpoint, one of the big- gest reasons I hear for a mistake is that they just cut and pasted from another design. They didn't really read them. They may not really understand the meaning of the notes that they're using. That's probably the number one reason I hear for errors. There's no designer out there that I know of who intentionally designs a bad board. It's just that they don't realize it. You see a lot of ODM designers who are designing a cellphone one day. The next day, they're designing a medical device. They just have no experience. They don't really understand what notes should be or shouldn't be on a drawing. That's probably my number one reason. Holden: One of my biggest issues is that a lot of times in Europe and the U.S., for simplic- ity, you standardize on a standard panel size. But in Asia, because the material is so much of the cost, they're a lot more sophisticated on panel size. Designers, if they know they're going to go offshore, don't find out really what the panel size is and what the border require- ments for a preferred vendor or something like that are. You can easily, in choosing board sizes, screw up the cost because, with 1/4" less in some dimension, we could increase the panel array quantity, reducing the cost per board. Maybe Americans are willing to waste the laminate, but in Asia, they don't like to waste laminate. Korf: That's very true. Also, we're still work- ing in a 1980s Gerber-based world where we have just a plotter language telling you what line and circle to draw. I need a piece of paper to interpret these lines and circles. I'm very active in the IPC-2581 committee. If you look at having intelligent data where you can attri- bute everything, a lot of these notes actually disappear. Like materials, they disappear. You just include the material spec in your stackup data. You don't need a drawing. You don't need a note. There's a lot of notes you don't need telling you what to do because it's already in the data. That's part of the 10-year transition as we move away from Gerber-based data to intelligent data that we can start getting rid of some of these notes. A lot of times, these notes contradict with the picture on the draw- ing and/or the data. If it's included in the data from the CAD system, then we'll start to see the elimination of both the notes and some of the issues. Holden: I can't figure out why Gerber still exists. Nothing else in electronics is 60 years old. If electronics are three years old, they're getting toward obsolescence, yet we're stuck. Korf: …on a plotter format from the 1960s. Exactly. One of the most common issues is that you get a board outline drawing on the fabrication print. You extract it from your data file, and they're different, or you get a netlist that doesn't match the data. I presented at IPC APEX EXPO a couple of years ago. I asked the audience, "When we ask the question, should we use the netlist extracted from the Gerber or the original netlist? What should we use?" Everyone responded, "Gerber," and then laughed. They all realized what a nonsensical answer it was.