Thermal stress generated by temperature change is greater than you’d imagine

Hello, everyone. I’m Takemori, manager for a technical department.

We don’t think about it much in our daily lives, but when the temperature of an object changes, it expands and contracts. The magnitude of expansion and contraction depends on the nature of each material (CTE, Coefficient of Thermal Expansion).

In this article, I will talk about the thermal stress caused by this thermal expansion and contraction.

A common design example that takes thermal expansion and contraction into account is the gap between the rails of a train. The rails are designed with gaps between the rails to prevent them from touching each other even if the temperature changes, because the rails are hot in summer and expand, and shrink at low temperatures in winter. If there are no gaps between the rails, there is a danger of the hard rails stretching and pushing against each other and bending during high summer temperatures due to thermal expansion (which can also lead to accidents). Therefore, it is important to take thermal expansion and contraction into account when designing products that are expected to change in temperature.

 

 

In the case of electronic devices, semiconductor components are soldered to PCBs. However, since each of these materials has a different CTE, they can expand or contract due to changes in environmental temperature. Thermal stress is generated in the connections (mainly soldering point) due to different amounts of shrinkage. Even if the thermal stress is small, repeated temperature changes can lead to a malfunction such as crack and fatigue failure at connections. We have received many inquiries about the verification of thermal stress to prevent these failures.

 

4-layered model

 

Based on many years of collaboration with semiconductor vendors and set manufacturers (e.g., automotive equipment, mobile devices, outdoor equipment, etc.), WTI not only knows the inner structure of semiconductor components, but also has the know-how to simulate them in a variety of operating environments. In addition, we have been using MARC by MSC Software as the simulation software for structural analysis, and we newly introduced ABAQUS by Dassault Systèmes (currently using two types of structural analysis software) in order to strengthen structural analysis, including linkage with case design (Pro/ENGINEER) and thermal fluid analysis (FloTHERM). We are ready to help you with all your thermal stress related concerns, so please contact us for a consultation.

 

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