Bridging Knowledge and Understanding of Thermal Management Materials

Estimated reading time: 11 minutes

Mayoh: Yes, we’ve tried to demonstrate the principal design options.

Starkey: And there’s another chapter on specifying the right material for the job, which again is something that we've just discussed as really one of the fundamentals.

Mayoh: Yes, we did try to take a neutral approach on this, but when you're making references, you do need to make some references to products that you know—obviously for Didier Mauve and me, they’re Ventec materials. One point I would like to emphasise is that some clarity is required in the marketplace regarding how these materials are tested and specified, in terms of their thermal conductivity. There are, and I don't think it's any secret, a number of low cost, dare I say, cheap producers of these materials in the marketplace.

Starkey: Don't necessarily take too much notice of their data sheet values?

Mayoh: No, absolutely, and I've been saying that for years. There are also different methods for testing the thermal conductivity of the dielectric, and some companies, some of the lower-volume—dare I again say cheap—producers have their own test methods. So, it's still a case of “buyer beware” and my advice is to work with a reputable source where you know that what it says on the data sheet is what you're going to get!

Starkey: I entirely agree Ian! Looking at the rest of the book, I see that as well as the chapter on the scope for the designer, there’s a summary of the sort of things that ought to be considered in terms of PCB fabrication and PCB assembly and some stuff on reliability. And there's an awful lot of useful technical information as appendices in the back of the book.

Mayoh: Yes, for sure. And that was drawing on the experience not just of myself and Didier, but our colleagues globally. In terms of PCB production, these things are never going to be easy to produce.

 Starkey: Could you expand a little on that?

Mayoh: Because they are full of fillers, which we need to help dissipate the heat, manufacturability will initially present a challenge, although not an insurmountable one. And as you know, we've now removed the glass fabric from our high-end, high thermal conductivity materials, although obviously it's still in the VT-5A2, so that we can produce pre-pregs and cores. But there's no doubt that the amount of fillers in these materials does present some challenges for producers, though with experience, like any new technology, they can be overcome.

Starkey: You mentioned hybrid constructions and bonding the materials.

Mayoh: I suppose we've moved into the hybrid construction scenario by default, in response to customer demand. People saw the advantages of using thermal materials and started producing multilayer constructions and bonding boards themselves, bonding double-sided or four-layer boards onto aluminium using a thermal pre-preg. And really our early materials, the VT-4A series, were designed purely as insulated metal substrates—copper bonded to aluminium—rather than for building hybrid constructions. But we’ve moved on, which is where the VT-5A2 comes in. It’s been designed for building hybrid constructions. It has a very similar thermal conductivity, but from the fabricator's point of view, it's making life a bit easier. However, like any new technology, processing and mechanical processing, will need some modifications! But in terms of bonding characteristics, it is much easier to use than the early-series materials.

Starkey: Ian, in this conversation you've referred to several of Ventec's product designations, but to your credit, you've kept the book completely objective and free from proprietary references, which is one of its great attributes.

Mayoh: Well, thanks Pete. As I say, we started out with trying to make it as neutral as possible but as I said earlier, when you're making references, you have to make references that you know and fully understand.

Starkey: Of course. But certainly, the technical information in the book is clear, objective, generic information, although in this conversation we've talked about some product-specifics.

I like the book; everybody that I've spoken to that has downloaded the book likes the book. And it’s been peer-reviewed by some well-known industry experts, including Alun Morgan, the chairman of the European Institute of Printed Circuits.

Mayoh: Yes, when we were writing this book, we wanted feedback from peer reviewers who were neutral to our company. And this is where Alun and his counterparts have given their objective opinions.

Starkey: Yes, I saw some of the peer reviews and yes, they were very objective, in some cases quite critical, and that's the very reason you asked these guys to review the draft before it was put together for publication. But if I could quote Alun Morgan’s comment: "This book is required reading for designers and end-users wishing to understand the science and practice of using insulated metal substrate materials.” I think that says it all.

Mayoh: I think it does.

Starkey: Thanks, Ian.

Mayoh: Thank you, Pete.

Visit I-007eBooks to download your copy of Ventec International’s micro eBook today: The Printed Circuit Designer's Guide to Thermal Management with Insulated Metal Substrates

• < Previous Page