Avoid Overbuilding your RF Printed Circuit Board

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Hofer: We're a quick-turn manufacturer in prototyping, and in many good R&D processes, an engineer can run a little bit late, because you always think of a way to do it better or something that you didn't address, and you have to go back and fix it. We find an incredible amount of demand for RF products in five days or less. The biggest problem that we run up against is a lot of the advanced dielectric manufacturers have lead times that exceed 20 or 30 days.

Rogers is a big name, but there's also Taconic out there, there's Isola making high-frequency products, and actually we're very excited by some of the products that Isola is developing. You've got Nelco in that arena as well, and the issue comes when somebody needs a board in five days; if you have to wait 10 or 15 or 20 business days to get material, it throws the whole project out the door. We combat that by stocking a lot of that material and taking it upon ourselves to make sure that we keep a min/max stock on hand so we can eliminate that lead time.

Matties: That's good. Not everybody has that ability.

Hofer: No, and I think that sets us apart. We got an engineer who needs to put a satellite up next year, and he's got this last board in design and he says, “I need this one in three days.” No problem, just hold on three weeks while I get the material. It just doesn't go over well.

Matties: Isn't part of the problem that we see, though, is these OEMs and engineers are spec’ing that material? Are you seeing a shift where they're giving you second-source approvals?

Hofer: With customers that are repeat customers, we're finding that they understand that we offer help at the beginning when they're doing that stack-up. We can then say, “Okay, if you run with this material, you might have a lead time of 20 business days. Here's two options. This one has a lead time of 5–7 days, this one we stock, or this one has a lead time of 10 days. Here are the performance differentials.”

Typically, between high-performance material manufacturers, you can see Dks within 0.1 between differing materials and loss tangents between 0.001 between different materials, and sometimes your design can handle that. If it can and the lead-time is much less, it's nice to have that option.

Matties: In terms of bringing new customers into the business, one of the things that we're looking at is the process of qualifying a vendor. There was a day when audits were just mandatory. Are you seeing a lot of audits demanded in your situation?

I think the industry is moving towards allowing the AS9000 certification and the MIL-certification to circumvent the audits. We still see some of the bigger OEMs maintaining an in-house auditor that goes out and does auditing. We've had a couple of smaller aerospace customers hire a third-party auditor to come in and audit, but I can say as an average, on-site audits are trending downward, because with the AS9100 certification, you've got audits every year. With the MIL-spec certification, we've got audits every two years, and those audits aren't just come in for a day like the old ISO audit. It's a three-day, two-man party that comes in and thoroughly vets the system. They're allowing your internal process controls and the certifications to suffice versus on-site audits.

Matties: Regarding the topic of lowering costs, there's obviously a big demand for lowering costs.

Hofer: There's always a demand for lowering costs.

Matties: What strategies do you bring, not necessarily to take the profit out of what you're doing, but to help your customers lower their costs?

Hofer: That's a very good question and difficult for a quick-turn prototype house, because one of the best ways to lower cost is have it built slower—increase your lead time. What we do is offer lower-cost alternatives. We help with the stack-up and the DFM at the beginning. We try to run some processes as lean as possible. It would be great if I could run my raw material very lean and just bring in material as I need it, but unfortunately the cost versus gains on lead times is not there.

What we try to do is offer design assistance and stack-up assistance to help use the most cost-effective performance materials and to make sure that the design is robust and gets you what you want the first run.

Matties: Don't overbuild it, and don't over-materialize it.

Hofer: I've had several people say, “Wow, why don't they just build the whole board out of Rogers?” Well, it's not cost-effective. Run some FR-4 in there. That's a fifth to a tenth of the price of the Rogers, where you don't need the Rogers. I've had other customers come up and say, “I've heard Rogers doesn't bond well with FR-4.” Well, as a manufacturer who has run literally every part number of Rogers that they've made, I've mixed 90% of them with FR-4 and they all work great.

I think there are also some misconceptions with some designers not understanding that they can mix and match materials to make the most cost-effective package.



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