Steinbeis experts develop measuring device for assessing the thermal conductivity of printed circuit boards
To a large extent, the service life of mechatronic systems is dictated by thermal loads. Whether it be power electronics, LEDs, or vehicle batteries, systems only work as they should do within specified temperature ranges. In addition to developing a type of innovative measuring device, experts at the Steinbeis Transfer Center for Heat Management in Electronics have also made a significant contribution to the corresponding IPC measurement standard. The new device can be used to determine the exact thermal conductivity of special printed circuit boards known as MBPBs, or metal-based printed boards.
The TIMTester developed by the Steinbeis Transfer Center for Thermal Management in Electronics
New systems are becoming increasingly compact, but also more and more powerful, resulting in continuous improvements regarding power density and waste heat. This heightens the crucial role played by heat management in the development of new technology: Every degree of temperature that can be controlled within a system, even within permissible temperature ranges, extends its service life. Current development efforts focus on new materials cable of removing heat more effectively from systems. This is where so-called thermal interface materials (TIMs) are particularly important in ensuring effective thermal coupling between components, for example by connecting battery cells to housings. To develop those interfacing materials and optimize the thermal performance of systems, it’s crucial to be able to take precise measurements of their thermal conductivity.
TIMTester – a success story
The Steinbeis Transfer Center for Heat Management in Electronics (ZFW) was early to take on this challenge, resulting in the development of a measuring device for characterizing TIMs. The first generation of its so-called TIMTester was awarded the 2013 Steinbeis Foundation Transfer Award – the Löhn Award. Since then, the Steinbeis experts from Walddorfhaslach have been producing and selling the device internationally to well-known companies. Over the years, further customer requests have been taken on and a number of new measurement features have been added. In addition to information on the heat transfer properties of TIMs, the current generation of devices provides valuable insights into aging behavior. For example, a sophisticated measurement technique makes it possible to fast-forward the aging rate of samples and take continuous recordings of their heat transfer properties. Materials can also be teased into failing in specific ways, allowing causes to be analyzed.
The IPC measurement standard
MBPB materials are a particular challenge when it comes to thermal characterization. MBPBs, i.e. metal-based printed boards, are printed circuit boards containing a metallic layer of aluminum or copper to keep materials cool. This technology is used in areas of electronics involving high power densities, such as LED applications. One particular challenge lies in laying precise contacts on samples and determining layer thicknesses. In the past, there have been extraordinarily wide variations in results between measurements taken in different laboratories using different equipment. This has made it difficult for manufacturers to meet required quality standards, and there have been calls from industry for a measurement standard for MBPB materials.
This was also picked up by the IPC, the global trade association that issues industry standards for electrical and electronics manufacturing, which approached the Steinbeis Transfer Center for Heat Management in Electronics with a request to capture the properties of the TIMTester in the form of a measurement standard. Subsequent to this request, discussions were held with international stakeholders in industry and science, and comparative quality assurance measurements were taken.
Steinbeis entrepreneur Professor Dr.-Ing. Andreas Griesinger is satisfied with the outcome: “The outstanding precision of the TIMTester has been confirmed on an international level. Our technology establishes a global basis for the thermal characterization of MBPB materials used in power electronic systems.” The next potential project with the IPC is already lined up, this time focusing on a new system developed by the Steinbeis team to be used for the thermomechanical analysis of thermally conductive materials.
Contact
Prof. Dr.-Ing. Andreas Griesinger (author)
Steinbeis Entrepreneur
Steinbeis Transfer Center Heat Management in Electronics (Walddorfhäslach)
Steinbeis Innovation Center Heat management (Walddorfhäslach)
www.zfw-stuttgart.com