E-NEWSLETTER l SEPTEMBER 2020
A MESSAGE FROM OUR CEO
This is an exciting time for us at American Standard Circuits as we have just released The Printed Circuit Designer’s Guide to Thermal Management: A Fabricators Perspective, our fourth book in what has been a very successful series. Make sure that you don’t leave this newsletter before downloading your free copy of what is being called the most definitive micro book on the fabrication of Thermal Management PCBs. While you’re at it make sure to download our other books in this series, if you have not done so already. You’ll find the links to all our books below as well as an interview I was asked to do about this new book. It will give you a good idea of what the book is about and who it is for.

Our goal at ASC is to educate our customers in what it takes to build various technology PCBs. We feel that it is our responsibility to make sure that you, our customers, have a good understanding of how a PCB is built. We want you to engineer and design the best, most economical, and producible PCBs possible.

Be sure to check out our Wednesday Webinars. We have done 11 Webinars so far and the feedback has been so positive that we plan to keep doing them through the end of the year. If there are any subjects you would like us to cover, please contact us. A link to "on demand" playbacks for all our webinars is included below. Let us know if you want to be notified about future webinars.
Thank you for all your support through these challenging times. Please stay safe, we look forward to seeing you soon.

Sincerely,

Anaya Vardya
President and CEO
American Standard Circuits
ANNOUNCING OUR NEW EBOOK!
Thermal management is one of the fastest-growing areas of the PCB segment, far outpacing the projected growth for the overall industry. While demand was originally driven by high-power telecommunication and mil-aero applications, it has rapidly expanded to include automotive, consumer electronics, and medical sectors.

Written by Anaya Vardya, this book serves as a desk reference for designers on the most current thermal management techniques and methods from a PCB fabrication perspective, including a case study on an extreme mixed-technology design. Vardya also shares considerations designers should discuss with their PCB fabricators to ensure manufacturability, cost-effective solutions, and successful product launches.
An excerpt from Dan Beaulieu’s interview with ASC CEO Anaya Vardya about the new Thermal Management ebook:

Beaulieu: What was your goal in writing this book?
Vardya: Primarily, we wanted to educate our readership when it comes to the various PCB thermal technologies available today. We feel that if we can contribute to the education of our customers, especially the engineers and designers, everything will run more smoothly. We wanted to give our customers insight into what it takes to build a thermal board. In short, the more our customers know about our PCB technology, the better we can work together in the end. We discuss design rules associated with the various different thermal management techniques.

Beaulieu: What is the audience for this book?
Vardya: The book is for professionals who have anything to do with designing PCBs, especially designers and engineers, as well as our customers and people who have an interest in PCBs in general and thermal PCBs specifically.

The interview is a three minute read and you can do so here:
Thermal Design Considerations In Metal Core Boards

Conceptually, a metal-core board is exactly like it sounds—the metal is in the middle of the PCB sandwiched between layers on both sides. Just about any PCBA that will contain active heat-generating components can benefit when designed on a metal-core PCB. On a conventional PCB, the standard FR-4 layers are relatively poor thermal conductors, and heat is normally dissipated from active components using vias and thermal pads. 

A metal core has much greater thermal conductivity, allowing it to easily dissipate heat away from active components. This prevents hot spots that can form in PCBs by dissipating heat evenly across the PCB and increasing performance and lifetime.

Some of the design factors that need to be considered include the following:

Core Materials/Prepregs 
The core materials and prepregs could be any PCB raw material. We have seen metal-core boards manufactured with polyimide, FR-4, or highly thermally conductive materials, but it really depends on the application and what is desired from an electrical/thermal management perspective. 

Metal Core 
Typically, either copper C110 or Aluminum 6061T6 are used with equal frequency, but the cost and weight need to be factored into the decision on which to use. 

Drilling the Metal Core 
The metal-core boards are drilled oversized with the entire drill pattern associated with the PCB—both the PTHs that go from the top layer to the bottom layer and the non-plated holes going from the top layer to the bottom layer. Occasionally, mounting or grounding holes have no clearance in the metal core. 
Insulator/Filler 
The insulator/filler material acts to insulate the PTHs from the metal core, so the entire PCB does not short out. The filler is bought in powder form and then is applied to the surface and holes and put in a multilayer lamination press to cure. This is a critical process because it must ensure there are no voids in the filler because once the PTH are drilled and plated, chemistry can leach back to the metal core through a void and cause a short. The core is then planarized (sanded) to remove the excess filler on the surface. The filler material is a ceramic/epoxy combination. 

Stackup 
It is preferred to be symmetrical in terms of the number of layers on top of the metal core and number of layers below the metal core. Also, copper weight symmetry is preferred between all the layers, like any multilayer PCB, because a lack of symmetry can lead to excessive warpage issues. It is important to note that due to the unique characteristics of metal-core designs, the typical IPC warpage specifications do not apply.
Milling on a metal-core PCB


Milling 
Most metal-core boards have milling associated with the PCB that results in exposing the metal-core layer on the edges or in cavities (Figure 3-4). 

Surface Finish on the Exposed Metal Core 
We recommend putting a surface finish on the exposed metal. Typically, for aluminum, we recommend chromate conversion and for copper a minimum of 50 micro-inches of electroplated nickel.

Excerpted from Chapter 3, “Metal Core Boards” in The Printed Circuit Designer's Guide to Thermal Management: A Fabricator's Perspective.” 
Check out our YouTube page for more information on thermal management
UPCOMING WEBINARS
Copper Foil
September 16
@ 11:00 am (CDT)

We will be discussing the manufacturing process for copper foil and the different kinds of copper foil available. We will cover the pro’s and con’s of the various foils and implications from a design perspective. We will also discuss the advanced copper foil offering such as MicroThin and when these should be utilized.

IMPCB/MCPCB
September 23
@ 11:00 am (CDT)

This webinar will focus on various IMPCB or MCPCB applications, different technologies, critical design parameters and processes. We will also discuss Metal core technologies and critical design parameters, as well as some of the material options available.
IMPCB Materials- Ventec
September 30
@ 11:00 am (CDT)

This webinar will explore the various Ventec materials for IMPCB applications.
CHECK OUT OUR OTHER BOOKS!
Click Here to download our Fundamentals of PCB Technologies e-book
Click Here to download our Fundamentals of RF & Microwave PCB’s e-book
Click Here to download our free Flex & Rigid-Flex Fundamentals e-book
Our Experts are one reason why American Standard Circuits is North America's leading independent PCB fabricator. Our entire experienced and professional staff is ready and able to make your next PCB project easy!