Pressure Sintering Substrate Recesses Thermal Resistance
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Solution Overview
Problem
The existing pressure sintering method for connecting power semiconductor components with a substrate results in concave areas on the substrate facing away from the components, leading to increased thermal contact resistance and less effective cooling due to different thermal expansion coefficients between the substrate and sintered metal.
Innovation Solution
A pressure sintering method involving a workpiece carrier with recesses, where the substrate is pressed into these recesses during sintering, allowing for a flat surface that can be securely attached to a metallic base plate or heat sink with low thermal contact resistance, reducing the risk of substrate cracking and optimizing thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pressure sintering is applied to connect power semiconductor components to substrate, then mechanical strength and electrical connection are improved, but concave areas form on substrate surface increasing thermal contact resistance
Solution Approach 1:
The workpiece carrier with recesses is prepared in advance to receive and accommodate the substrate. The recesses are pre-formed with specific geometry (depth, width, shape) to match the substrate characteristics, ensuring that when pressure is applied during sintering, the substrate is pressed into the recesses to form a flat outer surface while maintaining strong mechanical connection. This preliminary preparation prevents the formation of concave areas on the substrate surface that would otherwise increase thermal contact resistance.
Solution Approach 2:
The workpiece carrier acts as an intermediary element between the pressure stamp and the substrate. It transfers and distributes the pressing force uniformly across the substrate while providing the recesses that guide the substrate deformation. This intermediary structure enables controlled plastic deformation of the substrate into the recesses, achieving both strong mechanical bonding and a flat external surface for optimal thermal contact with the heat sink.
2Strength
If high pressure is applied during sintering to ensure strong bonding, then connection strength is improved, but substrate cracking risk increases
Solution Approach 1:
The workpiece carrier provides locally adapted pressing surfaces through its recesses. The recess geometry (varying depth, width, and shape in different regions) creates localized deformation zones that distribute the pressing force appropriately across the substrate. This local adaptation allows high pressure to be applied where needed for strong bonding while avoiding concentration of stress that would cause cracking in other regions of the substrate.
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 method ensures a substrate surface that can be efficiently cooled by minimizing thermal contact resistance, thereby enhancing the cooling effectiveness of power semiconductor components.
Implementation Method 1
application of a temperature treatment to the sintering material, wherein in doing so the sintering material is converted into a sintered metal, thereby forming the sintered connection of the power semiconductor components to a substrate
Implementation Method 2
a portion of the first region of the substrate is pressed into the first recess and a portion of the second region of the substrate is pressed into the second recess
Implementation Method 3
different thermal expansion coefficients of the substrate, in particular an electrically non-conductive insulation layer of the substrate (e.g. ceramic plate) and of the sintered metal and the power semiconductor components, as a result of the mechanical stresses arising between these components during the hardening stage
Data Source
AI summary
The invention provides a pressure sintering method including: a) providing a sintered component arrangement with a workpiece carrier having recesses, with a substrate resting on a main surface of the workpiece carrier, wherein a sintering material to be sintered is arranged between the power semiconductor components and the substrate, a first power semiconductor component and a first region of the substrate arranged above the workpiece carrier in the normal direction of the first main side of the insulation layer flush with a first recess of the workpiece carrier, and a second power semiconductor component and a second region of the substrate are arranged above the workpiece carrier in the normal direction of the first main side of the insulation layer flush with a second recess of the workpiece carrier and a step of b) pressurizing the power semiconductor components and applying a temperature treatment.