Mark your calendars to join our LIVE Q&A on material selection!
Post your questions in this thread and our experts will reply during this live Q&A which will be hosted on Zoom.
Notes:
This is not a webinar. There will not be any presentation. We will only answer questions during this session.
I often design power and analog electronics that work in lower frequency domain, but have to operate in high RF environments and therefore require strong RF immunity. Would it be beneficial to always use lower end (not smooth) copper layers to help increase higher frequency loss in an attempt to improve HF immunity results?
I’m designing a 5G antenna module with operating frequencies in the millimeter-wave range. SI is crucial, I need a material with a low dielectric constant and minimal loss tangent. I’ve considered Rogers 4350B, but I’m worried about its manufacturability. What other materials should I consider that balance performance with fab yields?
My current project involves a power amplifier board that handles high current and generates a lot of heat. I’m using 2 oz copper for the power planes, but I’m unsure which material offers the best thermal conductivity while still being cost-effective. How do materials like FR4 or metal-backed PCBs compare in this scenario?
I’m designing a high speed data transfer circuit that needs to operate at 10Gbps. I need controlled impedance and I know the Dk of the material has some impact. I’ve been looking at Isola and Panasonic materials, but I’m not sure how much the Dk variation impacts real world signal speed. Any advice?
Immersion silver finish: Is there anything special that I should consider before reflow soldering? It would be for a 2-sided board. I am worried about tarnish on the silver, especially after the first-side reflow.
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I am designing a 100A PCB do you have any recommendations for PCB foil and stack-up?
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I am looking to design some ceramic PCBA. What are the options for it. I can find many vendors from china doing this, but I have trouble finding a vendor in USA. What are the challenges?
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Can you explain about FR4 material and how we can identify the surface finish on the bare PCB after fabrication?
I’ll attempt to summarize, both for my own understanding and for helping later searches.
(1) If your signals are lower frequency but you have to reject high-frequency interference, should use you use intentionally lower-quality/rougher copper? This seems to be an empirical question without a well-known answer.
(2) Rogers 4350B isn’t super-easy to work with, but Sierra (and Rogers) have done it enough by now that you can safely choose it without worrying about the effects on yield.
(3) Thermal: Metal-backed PCBs can work, so can metal core with flanges at the sides. There are also some Rogers materials with better (about double?) thermal conductivity through the dielectric. But without specific numbers for exactly how much heat, the first thoughts should normally be whether you have sufficient copper and thermal vias and spacing, rather than about about which material to use for the dielectric.
(4) 10 Gbps is now fairly routine. You do need a high-speed material, but don’t worry too much about which high-speed material.
(5) 100 amps is a lot. Enough that they have many followup questions before they can really answer. You’ll need thick copper, but the stackup may be the least of your problems – what sort of connector are you using to get that in and out of your board?
(6) Immersion Silver should generally be avoided, but sometimes it is needed. It has a short shelf life and can be fragile, but it does solder OK if it is fresh. Also talk to the assembly guys (Tony and Mehdi?)
(7) Ceramic – why is it hard to find US vendors? Because it is a very different process, which requires different machinery and tools and different expertise. (Print and fire in a furnace/kiln instead of plating and etching off?)
(8) How to ID the surface finish? Why do you want to know? [My assumption had been “someone handed me a board to learn from or reverse engineer”, but maybe that isn’t the sort of question which gets escalated to the experts.] Were you looking for a specific test, or is this an audit on the fab house, or what?
(9) What is FR-4? Too broad of a question, like asking a homebuilder to explain “wood”. FR-4 covers a lot of very different materials. As a starting point, they tend to be strong and fire-resistant when solid, but to have an epoxy component that flows to fill in gaps when you heat it during board fabrication.
off-topic: Who is the interviewer, and where is her accent from? It somehow sounds both Indian and French, which is a combination I hadn’t heard elsewhere.
What are the reasons that you would use Immersion Silver? From a web search, it sounds like it is slightly cheaper than ENIG, but tarnishes easily.
There are also suggestions (but I didn’t find clear answers) of other advantages/disadvantages. flatter? better electrical connection? Works better at fine pitch? Works better for high-speed signals?
Less durable, both mechanically and electrically?
It’s me. Just French. But I did live in India for 5 years so might have picked up a bit of an accent there. 