Sinterable Paste and Polymer TIM for Multi-Chip Thermal Management
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Solution Overview
Problem
Multi-chip packages with varying die heights pose challenges in achieving consistent thermal conductivity and compliance, leading to uneven thermal resistance and reduced cooling efficiency due to the limitations of traditional thermal interface materials.
Innovation Solution
A thermally conducting, no-slump sinterable solder paste is applied to create a flat plateau over the dies, followed by a compliant polymer thermal interface material (PTIM) to absorb die height variations and ensure consistent thermal conductivity, while a heat spreader is attached to manage heat effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional thermal interface materials are used on multi-chip packages with varying die heights, then the packaging structure is simple, but the thermal conductivity becomes inconsistent and thermal resistance increases
Solution Approach 1:
A compliant polymer thermal interface material (PTIM) is introduced as an intermediary layer between the heat spreader and the multi-chip package. This PTIM layer accommodates die height variations and maintains consistent thermal contact, resolving the contradiction between thermal conductivity consistency and package structure complexity by adding a functional intermediary that absorbs dimensional variations.
Solution Approach 2:
The patent changes the physical parameters of the thermal interface material by using a compliant polymer material with specific viscosity and thermal conductivity properties. This material can deform to accommodate height variations while maintaining thermal contact, thus improving thermal conductivity consistency without requiring complex active control mechanisms.
2Temperature
If aggressive thermal solutions are implemented to account for different chip heights, then thermal performance improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The thermal management system is segmented into distinct functional layers: a heat spreader layer, a compliant polymer thermal interface material layer, and the multi-chip package layer. This segmentation allows each layer to be optimized independently for its specific function, improving heat dissipation effectiveness while maintaining ease of manufacture through modular assembly.
Solution Approach 2:
The patent employs a thermal interface material with specifically controlled rheological parameters (viscosity, compliance) and thermal properties. By changing these material parameters, the system achieves effective heat dissipation across varying die heights without requiring complex manufacturing processes or active control systems.
3Reliability
If a flat heat spreader is used on uneven die surfaces, then manufacturing is simple, but thermal contact is uneven and thermal resistance increases
Solution Approach 1:
The patent uses a flexible compliant polymer thermal interface material as a thin film between the rigid flat heat spreader and the uneven die surfaces. This flexible material conforms to the varying die heights, ensuring uniform thermal contact across all chips while maintaining a simple flat heat spreader design, thus improving thermal contact consistency without adding interface structure complexity.
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 solution provides high thermal conductivity and compliance, maintaining consistent thermal performance across dies with varying heights, reducing thermal resistance and enhancing cooling efficiency by ensuring uniform bond-line-thickness and accommodating package warpage and lid flatness variations.
Implementation Method 1
A thermally conducting, no-slump sinterable solder paste is applied to create a flat plateau over the dies
Implementation Method 2
A layer of a thermally conducting sintered paste over the top of each die
Implementation Method 3
a compliant polymer thermal interface material (PTIM) to absorb die height variations
Data Source
AI summary
In some embodiments a semiconductor die package includes a package substrate, a plurality of dies each attached to the package substrate, a layer of a thermally conducting sintered paste over the top of each die, a layer of flexible polymer thermal interface material over the sintered paste, and a heat spreader over and thermally connected to the polymer thermal interface material.