Graphite-Lined Thermal Interface Structure for DUT Heat Dissipation
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Solution Overview
Problem
Conventional thermal interface materials (TIM) used in pressing test devices for semiconductor packages suffer from limited thermal conductivity, leading to overheating, contamination, and inaccurate test data due to heat accumulation, which can damage the device under test (DUT) and affect test results.
Innovation Solution
A heterogeneous thermal interface material element comprising a graphite liner and a soft thermal conductive sheet, where the graphite liner has higher thermal conductivity and the soft thermal conductive sheet has higher ductility, forming a C-shaped bag structure with air gaps to enhance heat dissipation and contact area with the DUT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermal interface material is used to fill the gap between pressing connector and DUT, then the gap can be filled and electrical testing can be conducted, but the TIM cannot effectively conduct heat away causing heat accumulation that fuses the TIM and contaminates the DUT surface
Solution Approach 1:
The patent uses a composite thermal interface material consisting of a graphite layer combined with a soft thermal conductive sheet. The graphite layer provides high in-plane thermal conductivity to rapidly conduct heat away from the DUT contact area, while the soft thermal conductive sheet fills gaps and ensures good thermal contact. This composite structure effectively prevents heat accumulation and TIM fusion, solving the contradiction between maintaining test accuracy and preventing overheating.
Solution Approach 2:
The patent changes the thermal conductivity parameter of the interface material by selecting graphite with high in-plane thermal conductivity coefficient. This parameter change enables the TIM to effectively conduct heat away from the pressing connector-DUT interface, preventing the heat accumulation that would otherwise cause TIM fusion and contamination, thereby maintaining both reliable testing and appropriate temperature management.
2Device complexity
If TIM with limited thermal conductivity is used, then the structure remains simple and cost-effective, but heat accumulation occurs causing contamination and potential DUT damage
Solution Approach 1:
The patent applies composite materials by combining graphite with a soft thermal conductive sheet. The graphite layer provides superior in-plane thermal conductivity to prevent heat accumulation and contamination, while the soft sheet ensures good contact. This composite approach addresses the harmful effects of overheating and contamination without excessively complicating the TIM structure, as the layers are simply stacked and pressed into place.
Solution Approach 2:
The soft thermal conductive sheet used in the patent has porous or flexible characteristics that allow it to conform to surface irregularities and fill gaps between the pressing connector and DUT. This porous structure enhances thermal contact area and effectiveness while maintaining relative structural simplicity, preventing contamination and overheating without requiring complex designs.
3Ease of manufacture
If a single-material TIM is used, then manufacturing is simple, but the TIM cannot simultaneously provide high thermal conductivity and high ductility to adapt to surface irregularities
Solution Approach 1:
The patent uses a composite structure where a graphite layer is combined with a soft thermal conductive sheet. The graphite layer provides high thermal conductivity, while the soft sheet provides high ductility and adaptability to surface irregularities. This composite approach enables the TIM to simultaneously achieve both high thermal performance and good conformability without requiring complex manufacturing processes, as the layers are simply stacked and pressed together.
Solution Approach 2:
The patent applies local quality by assigning different functional properties to different layers of the TIM. The graphite layer is positioned to provide high in-plane thermal conductivity where heat conduction is most needed, while the soft thermal conductive sheet is positioned to provide ductility and adaptability to surface irregularities. This functional differentiation within the composite structure allows each material to excel at its specific function while maintaining ease of manufacture through simple layering.
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
The combination of materials with different characteristics improves heat dissipation efficiency, reducing overheating risks and ensuring accurate test data by increasing the contact area and extending the thermal conductivity, thus protecting the DUT from damage.
Implementation Method 1
a thermal conductivity coefficient of the graphite liner is greater than a thermal conductivity coefficient of the soft thermal conductive sheet
Implementation Method 2
a ductility of the soft thermal conductive sheet is greater than that of the graphite liner
Data Source
AI summary
A heterogeneous thermal interface material element includes a graphite liner and a soft thermal conductive sheet. The graphite liner has an upper layer, a lower layer opposite to the upper layer, an arc-shaped portion integrally connected to the upper layer and the lower layer so as to mutually form a C-shaped bag structure, and a sealing portion. The soft thermal conductive sheet is completely received in the C-shaped bag structure and sandwiched between the upper layer and the lower layer. The C-shaped bag structure is formed with a bag mouth sealed by the sealing portion. The soft thermal conductive sheet and the graphite liner are different materials. The thermal conductivity coefficient of the graphite liner is greater than that of the soft thermal conductive sheet, and the ductility of the soft thermal conductive sheet is greater than that of the graphite liner.