Floating Heat Spreader for Semiconductor Package Thermal Management
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Solution Overview
Problem
Conventional semiconductor packages face challenges in heat dissipation due to height variations of semiconductor dies, which require compliant materials with high thermal resistance, leading to increased thermal resistance and inefficiencies in heat management.
Innovation Solution
A semiconductor package design featuring a floating heat spreader with a spreader protrusion that extends into recesses in the mold compound, allowing for thermal coupling without direct contact, thus minimizing thermal resistance and accommodating varying die heights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat spreader is placed directly over semiconductor dies to enhance thermal performance, then heat dissipation is improved, but the height variation of different dies makes it very difficult to directly connect the heat spreader with each semiconductor die
Solution Approach 1:
The patent introduces a compliant layer as an intermediary between the heat spreader and semiconductor dies. This compliant layer accommodates height variations of different dies while maintaining thermal contact, solving the contradiction between improving heat dissipation and accommodating manufacturing precision variations.
Solution Approach 2:
The patent changes the physical state of the interface material from rigid to compliant, allowing the heat spreader to adapt to varying die heights. The compliant layer can deform to match the height variations, enabling direct connection without sacrificing thermal performance.
2Manufacturing precision
If compliant material is applied to each die to eliminate height variation and enable heat spreader contact, then mechanical contact is achieved, but the compliant material has relatively high thermal resistance and significantly increases the thermal resistance of the whole package
Solution Approach 1:
The patent carefully controls the thickness and material properties of the compliant layer to minimize thermal resistance while maintaining mechanical compliance. By optimizing these parameters, the compliant layer achieves height uniformity without significantly increasing thermal resistance.
Solution Approach 2:
The patent applies the compliant material only where necessary - at the interface between the heat spreader and dies - rather than throughout the entire package. This localized application minimizes the overall thermal resistance impact while still achieving the necessary height accommodation.
3Manufacturing precision
If compliant material is applied to each die to accommodate height variations, then mechanical contact is enabled, but due to different amounts of compliant material applied to each die, the increase of thermal resistance for each die will be different
Solution Approach 1:
The patent uses a single type of compliant material with standardized properties for all dies, making the solution universal. This approach ensures consistent thermal resistance characteristics across different dies while still accommodating individual height variations through the compliant nature of the material.
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 floating heat spreader design enhances thermal performance by maintaining thermal conductivity while avoiding the use of compliant materials, ensuring consistent heat dissipation across semiconductor dies with varying heights.
Implementation Method 1
The heat spreader, which includes a spreader body and a first spreader protrusion, hangs over the first flip-chip die. The spreader body is thermally coupled to the top surface of the first die substrate... ensures consistent heat dissipation across semiconductor dies with varying heights
Data Source
AI summary
The present disclosure relates to a semiconductor package, which includes a carrier, a flip-chip die, a mold compound, and a heat spreader. Herein, the flip-chip die includes a device layer over the carrier and a die substrate over the device layer. The mold compound resides over the carrier and surrounds the flip-chip die. The mold compound has a recess adjacent to the flip-chip die, and the recess extends vertically lower than a top surface of the die substrate. The heat spreader hangs over the flip-chip die, and includes a spreader body that is thermally coupled to the die substrate, and a spreader protrusion that extends from the spreader body into the recess. A thickness of the spreader protrusion is shorter than a depth of the recess, and a width of the spreader protrusion is narrower than a width of the recess, such that the spreader protrusion is floating in the recess.