Wafer-Level Thermal Sheet for Chip Scale Package Heat Dissipation
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Solution Overview
Problem
Wafer level chip scale packages lack effective thermal dissipation mechanisms, limiting their use to low-power, slow-speed applications due to the absence of thermal conductive media on their back surface, which increases manufacturing costs and complexity.
Innovation Solution
A thermal sheet with a thermal interface material layer and a conductive layer is attached to the non-active side of the wafer, providing an alternative path for heat dissipation and maximizing surface contact for thermal transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wafer level chip scale package is used to minimize packaging process complexity and package dimensions, then manufacturing cost is reduced and package size is minimized, but thermal dissipation capability deteriorates due to absence of thermal conductive medium on back surface
Solution Approach 1:
The thermal management solution is segmented into two distinct functional layers: a thermal interface material layer for direct thermal contact with the wafer, and a thermally conductive layer for heat dissipation. This segmentation allows each layer to be optimized independently while maintaining the simplicity of the wafer-level packaging process.
Solution Approach 2:
A thermal sheet comprising a thermal interface material layer and a thermally conductive layer is introduced as an intermediary structure between the wafer back surface and the ambient environment. This intermediary provides the necessary thermal conductive medium without requiring modifications to the wafer itself, thus maintaining manufacturing simplicity while improving thermal dissipation.
2Temperature
If thermally conductive materials are attached to the back surface of the wafer to improve thermal dissipation, then thermal dissipation capability is improved, but manufacturing cost increases and process complexity increases due to additional processing steps
Solution Approach 1:
The thermal interface material function and the thermal conduction function are merged into a single integrated thermal sheet structure. This combination eliminates the need for separate processing steps to apply different thermal management materials, reducing both process complexity and manufacturing cost while maintaining effective thermal dissipation.
Solution Approach 2:
The thermal sheet serves multiple functions simultaneously: it provides thermal interface contact, conducts heat away from the wafer, and can be applied using standard lamination processes already present in wafer-level packaging. This multi-functionality reduces the need for additional specialized processing steps.
3Temperature
If thermally conductive materials are attached to the back surface of the wafer to improve thermal dissipation, then thermal dissipation capability is improved, but manufacturing cost increases
Solution Approach 1:
The thermal sheet uses cost-effective materials including thermally conductive polymers and metal foils that can be applied as a disposable layer during the packaging process. This approach avoids the need for expensive permanent thermal management solutions while providing adequate thermal dissipation for the application lifecycle.
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 enables flexible and scalable thermal management, reduces manufacturing costs, and improves thermal dissipation efficiency, supporting higher chip densities and performance while maintaining a low-cost, compact package design.
Implementation Method 1
attaching the thermal sheet on a non-active side of the wafer, wherein the thermal sheet comprises a thermal interface material layer and a thermal conductive layer
Data Source
AI summary
A wafer level chip scale package system is provided forming a wafer having an interconnect provided on an active side, forming a thermal sheet having a first thermal interface material layer and a thermal conductive layer, and attaching the thermal sheet on a non-active side of the wafer.