Issue link: https://iconnect007.uberflip.com/i/1509257
36 DESIGN007 MAGAZINE I OCTOBER 2023 I had to explain something so many times out of frustration, "Hey, these are the rules, and if you don't follow them, I'll give you examples of what happens." Now, when somebody calls me with a question, I can reply with, "Let me give you this write-up." It helps them and gives them something to fall back on. Matties: We know that many designs go through respin after respin. How do you help your customers reduce respins? It's important for them to collaborate with the fabricator, whoever it is. It's important for them to understand their IPC design rules. One clas- sic mistake is not having enough annular ring for the class 3 that you said you want. You may have a 7-mil annular ring, and yes, that's fine for the finished hole size, but the rule is based on the mechanical drill that I have to use to fin- ish at that size. If it's immer- sion gold or ENIG, you've lost two mils of annular ring. If we can have that collaboration and share our expertise with them as they're laying it out, it reduces failures and respins. For instance, with rigid-flex boards, IPC- 2223 says that vias have to stay 125 mils away from the transition area from the rigid to flex. Customers ask if they can go down to 100 mils or 30 mils. No, but you can go to 200 mils all day long. Here's what happens: Designers see the big strip of open area, and they think, "Let's put vias there." But land voids exist there, and if you drill and hit a void, the chemistry will go in and short out to another plane. If the clearance was just another 20 or 30 mils away, this would never have happened. Or you end up with final drill in the transition area that's too close to the bend area, and those are the ones that fail. e whole landscape gets affected. But if you know the rules and apply them, it's like butter. Designers would benefit greatly if they read the design specs too. ey don't have to mem- orize them; just know the sections. When they think they need to bend a rule here or there, they can go read what the rule says, possibly even look at IPC-6012, and see what the fabri- cator has to say. If it looks like a challenge, then call a fabricator and ask if they can do this. Matties: Do your customers come to you requesting feedback about their designs? Sure. I had a customer who asked if we could review six part numbers that had been under development for three years. ey were going to production now. is was our last chance to change anything, because aer that it's going to b e f light- cer t if ied and then it would be impossible to change. I thought, "Man, now I have to do more homework." This is where we use intelligent data. I wanted to look at stackup. What was the major fallout cro ss-s ec- tion? But our automation team can provide all of this, and it was very valuable to the customer when I said that we could do this systematically. Our IT guy said that we are really programmers who data-mine our ERP soware. On a post-DFM build, I just put in the tool number, hit "Make a report," and I get all that information in about a minute: Yields are 95%. Here are the questions, and make sure you fix these so we don't have these same questions again. Go back and fix your drawing, because a lot of times, they don't, and we'll have the same question on the next rev. Matties: That's one of the greatest challenges the industry faces. Obviously, you have resources, but when you consider the smaller companies, many of them won't have resources for systems like this. If we can have that collaboration and share our expertise with them as they're laying it out, it reduces failures and respins.