Multi-Surface Compliant Heat Removal for Semiconductor Packages
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Solution Overview
Problem
Conventional semiconductor packages face challenges in achieving precise bond line thickness (BLT) of thermal interface materials, leading to inefficient thermal management and increased thermal resistance, particularly when dealing with components of varying heights and designs.
Innovation Solution
A semiconductor package assembly process that involves attaching dies to a substrate, applying a lid-attach thermal interface material after heating the die to a target temperature, and using a multi-surface compliant heat removal process with phase change materials and non-adhesive films to achieve controlled BLT and thermal efficiency across multiple components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lid attach process is used, then assembly is simple, but bond line thickness control is poor leading to increased thermal resistance
Solution Approach 1:
The die is pre-heated to a target temperature (e.g., 100°C to 200°C) before applying the lid-attach thermal interface material. This preliminary heating action modifies the die's physical state to improve subsequent TIM application and bonding, ensuring better BLT control and thermal contact without requiring complex assembly adjustments
Solution Approach 2:
The process changes the temperature parameter of the die from ambient to a target temperature range before TIM application. This parameter change affects the die's thermal expansion, surface properties, and TIM rheology, enabling precise BLT control and reduced thermal resistance through optimized thermal interface
2Reliability
If multiple heat rejecting devices are used for multiple components, then thermal management is effective, but device complexity and power consumption increase
Solution Approach 1:
Multiple heat-generating components (e.g., CPU, GPU, memory) are thermally coupled to a single shared heat rejecting device through各自的TIM layers. This merging approach consolidates multiple thermal management paths into one unified system, reducing the total number of heat sinks while maintaining effective heat removal from all components
Solution Approach 2:
A single heat rejecting device performs multiple functions by serving as the thermal management solution for multiple different components simultaneously. The heat sink is designed to accommodate various component geometries and thermal requirements through a common mounting interface and thermal path
3Adaptability or versatility
If components of varying heights are cooled by a single heat rejecting device, then design is simplified, but achieving uniform bond line thickness becomes difficult
Solution Approach 1:
A compliant lid or intermediate layer is introduced between the heat rejecting device and components of varying heights. This intermediary element deforms to conform to the different component topographies, maintaining uniform TIM thickness and optimal thermal contact across all components despite their height variations
Solution Approach 2:
The lid or mounting structure is designed with dynamic compliance, allowing it to deform and adapt to different component height profiles during assembly. This dynamic adjustment enables the system to maintain consistent BLT across components with varying geometries without requiring precise pre-positioning
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 process results in a more controlled BLT, reduced thermal resistance, lower junction temperatures, and the ability to use a single heat rejecting device across multiple components, simplifying design and reducing power consumption and fan speeds.
Implementation Method 1
applying a phase change material on each of the one or more components other than the primary component
Implementation Method 2
placing a lid-attach thermal interface material on the one or more die
Data Source
AI summary
A multi-surface compliant heat removal process includes: identifying one or more components to share a heat rejecting device, applying non-adhesive film to the one or more components, identifying a primary component of the one or more components, and applying phase change material on each of the one or more components other than the primary component. The phase change material is placed on top of the non-adhesive film. The process further includes placing the heat rejecting device on the corresponding one or more components and removing the heat rejecting device from the corresponding one or more components. The phase change material and the non-adhesive film remain with the heat rejecting device. The process also includes reflowing the phase change material on the heat rejecting device, removing the non-adhesive film from the heat rejecting device, placing a heatsink-attach thermal interface material on the one or more components, and placing the heat rejecting device on the corresponding one or more components.