-
- News
- Books
Featured Books
- design007 Magazine
Latest Issues
Current IssueBreaking High-speed Material Constraints
Do you need specialty materials for your high-speed designs? Maybe not. Improvements in resins mean designers of high-speed boards can sometimes use traditional laminate systems. Learn more in this issue.
Level Up Your Design Skills
This month, our contributors discuss the PCB design classes available at IPC APEX EXPO 2024. As they explain, these courses cover everything from the basics of design through avoiding over-constraining high-speed boards, and so much more!
Opportunities and Challenges
In this issue, our expert contributors discuss the many opportunities and challenges in the PCB design community, and what can be done to grow the numbers of PCB designers—and design instructors.
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - design007 Magazine
Book Excerpt: The Printed Circuit Designer’s Guide to... Thermal Management with Insulated Metal Substrates, Vol. 2, Chapter 3
March 1, 2024 | I-Connect007 Editorial TeamEstimated reading time: 1 minute
Chapter 3: Thermal Resistance/Impedance and Measurement
Note that several measurement methods are in common use and typically produce different results. Obviously, this can cause confusion. The Rth value of a thermal resistance, or its thermal conductivity, is meaningless if the test method is not specified.
Following is a brief review of the different measurement methods:
ASTM E1461
The image on the left in Figure 3.1 shows the experimental setup and measurement principle for the test method ASTM E1461 (Standard Test Method for Thermal Diffusivity by the Flash Method). This is a contactless test method for high-temperature testing using a laser. One surface of the test sample is irradiated with a flash of the laser and the thermal transfer to the other side is measured using an infrared detector.
A test sample measured according to ASTM E1461 was shown to have thermal conductivity of 3.3 W/mK.
ISO 22007-2
The center diagram in Figure 3.1 describes the test setup and measurement principle for testing according to the ISO 22007-2 transient plane heat source (hot disc) method. This method allows fast testing and high accuracy, eliminating opportunities for measurement failures and yielding a value without transfer losses. The test sample needs to be at least 3 mm thick.
Using this setup to test the same sample as in the previous ASTM E1461 test showed the thermal conductivity to be 5 W/mK.
ASTM D5470
The diagram on the right in Figure 3.1 describes the test method ASTM D5470. A heat flow is set up through the sample, establishing a temperature gradient that is measured in the steady state. The thermal conductivity/resistance of the sample is then calculated using a method described in the standard.
Suggested Items
TRI Opens New Manufacturing Facility
05/16/2024 | TRITest Research, Inc. (TRI), the leading test and inspection systems provider for the electronics manufacturing industry, announced that it has opened a state-of-the-art R&D and manufacturing facility.
Real Time with… IPC APEX EXPO 2024: Circuit Board Testing Strategies and the Impact of AI
05/08/2024 |Editor Marcy LaRont speaks with Bert Horner, president of The Test Connection, about the importance of strategic planning and design-for-test (DFT). Bert touches on some common mistakes that occur when DFT is not adequately considered early on. The discussion outlines an overarching industry need for a culture shift toward increasingly higher levels of integration and collaboration. Bert mentions that AI now has an influence on testing, as everywhere else, and announces his forthcoming book.
Real Time with… IPC APEX EXPO 2024: Understanding Objective Evidence in Manufacturing Processes
05/07/2024 | Real Time with...IPC APEX EXPOGraham Naisbitt explains the importance of objective evidence in manufacturing processes, debunking the common misconception that the ROSE test is a cleanliness test. He also discusses the introduction of Rev J, a requirement for measuring ionic contamination on circuit assemblies, and the challenges in accurately measuring contamination. Alternative methods like ion chromatography and the need for updating standards like the ROSE test are mentioned.
U.S. Air Force Secretary Kendall Flies in AI-Piloted X-62A VISTA
05/06/2024 | Lockheed MartinLockheed Martin Skunk Works joined the U.S. Air Force Test Pilot School and other government and industry partners in hosting U.S. Secretary of the Air Force Frank Kendall to fly in the X-62A Variable In-flight Simulation Test Aircraft (VISTA), a one-of-a-kind aircraft modified to test artificial intelligence (AI) and autonomy capabilities.
Real Time with… IPC APEX EXPO 2024: Software Solutions for Circuit Board Challenges
05/03/2024 | Real Time with...IPC APEX EXPONolan Johnson speaks with Will Webb from Aster Technologies about their software solutions for design teams, manufacturing, test engineers, and process engineers. Aster's software addresses the increasing complexities of circuit boards and the need for alternative testing methods.