Power Module Support Pillars Matched for Thermal Expansion
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Solution Overview
Problem
Power modules experience defects in pin connections due to thermal expansion differences between the casing material and pin material, leading to mechanical stress and potential damage during thermal cycling.
Innovation Solution
Incorporating support pillars with coefficients of thermal expansion matching those of the pins, which are either unitary and separate from the casing or integrated with it, to absorb thermal expansion forces and prevent damage to connection points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If support pillars with different thermal expansion coefficients are used, then the structural support function is achieved, but thermal stress damages the connection points during thermal cycling
Solution Approach 1:
The support pillars are made from a material having a coefficient of thermal expansion that is substantially the same as the coefficient of thermal expansion of the pins. This homogeneity in thermal expansion properties between the support pillars and pins eliminates differential thermal stress during temperature cycling, preventing damage to the solder joints while maintaining structural support functionality.
2Reliability
If the casing material has different thermal expansion properties than the pins, then the casing provides structural enclosure, but thermal cycling causes mechanical stress and connection defects
Solution Approach 1:
The support pillars are made from a material having a coefficient of thermal expansion that is substantially the same as the coefficient of thermal expansion of the pins. This homogeneity in thermal expansion properties between the support pillars and pins eliminates differential thermal stress during temperature cycling, preventing damage to the solder joints while maintaining structural support functionality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces or eliminates defects in pin connections by minimizing thermal expansion-induced forces, thereby enhancing the performance, lifetime, and reliability of power modules across a wide temperature range.
Implementation Method 1
The support pillars have a coefficient of thermal expansion that approximately equals a coefficient of thermal expansion of the pins. The approximately equal thermal expansion coefficients can prevent damage to any of the connection points when the power module and an electronic substrate, which is press-fit with the pins and supported by the support pillars, are thermally cycled
Data Source
AI summary
A power module can include a casing mounted to a baseplate that contains a substrate with circuitry. The circuitry can include pins for coupling signals to/from the circuitry. These pins can extend through a cover portion of the casing so that an electronic substrate, such as a printed circuit board (PCB) can be press-fit onto the pins. When press-fit, the electronic substrate is supported and positioned by support pillars that extend from the base plate to above the cover portion of the casing. If the pins and the support pillars have different coefficients of thermal expansion, damage to connection points between the pins and the circuitry may occur. Here, a power module is disclosed that has thermally matched pins and support pillars so that when the system is thermally cycled over a range of temperatures, the connection points are not damaged by forces induced by thermal expansion.