Thin Heat Sink with Localized Thickness for Warpage Control
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Solution Overview
Problem
Semiconductor packages with thin or short heat sinks face challenges in thermal dissipation and warpage due to differences in thermal expansion coefficients between the heat sink and resin, leading to potential degradation in thermal performance and mechanical stability.
Innovation Solution
A semiconductor package design featuring a thin and short heat sink with an exposed face for direct contact with an external heat sink, reducing warpage and maintaining thermal resistance by concentrating heat transfer near the die, while using a resin-mounted screw hole for attachment, which accommodates the heat sink's reduced size without significant degradation in thermal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the heat sink is made thin and short to reduce material usage and cost, then copper usage is reduced and cost decreases, but thermal dissipation performance deteriorates and warpage increases
Solution Approach 1:
The heat sink is designed with non-uniform thickness, featuring a thicker portion directly beneath the die for optimal heat extraction and a thinner portion toward the periphery to reduce material usage. This localized variation in thickness allows the heat sink to maintain effective thermal contact with the die while minimizing overall copper consumption and reducing warpage susceptibility.
2Loss of substance
If the heat sink is made thin and short to reduce material usage, then copper usage is reduced, but warpage increases due to thermal expansion differences
Solution Approach 1:
The heat sink features a thicker portion beneath the die that provides sufficient structural rigidity and thermal mass to minimize warpage in the critical heat transfer zone, while the thickness reduces toward the periphery to reduce overall material usage and cost.
3Loss of substance
If the heat sink is made thin and short, then material cost decreases, but thermal resistance increases
Solution Approach 1:
The heat sink is designed with a thicker portion directly beneath the die to maintain low thermal resistance at the critical heat transfer interface, while the overall reduced size and thinner peripheral portions minimize material usage and cost.
4Ease of manufacture
If the heat sink is made thin and short, then manufacturing cost decreases, but mechanical stability deteriorates
Solution Approach 1:
The heat sink features a thicker portion beneath the die that provides sufficient mechanical strength and structural stability in the critical load-bearing zone, while the overall reduced size and thinner portions reduce material cost and simplify manufacturing.
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 design effectively reduces warpage and maintains or slightly improves thermal resistance, achieving mechanical stability and cost reduction by minimizing copper usage, with minimal impact on thermal dissipation performance.
Implementation Method 1
The heat sink 104 may be thinner and/or shorter... The exposed face 114 of the heat sink 104 forms part of the back face 122... to directly contact an external heat sink
Implementation Method 2
Semiconductor packages with thin or short heat sinks face challenges in thermal dissipation and warpage due to differences in thermal expansion coefficients between the heat sink and resin
Data Source
AI summary
A semiconductor device including: a heat sink, a die on the heat sink, resin encapsulating the die, and a mounting aperture in the resin having at least a segment between the heat sink and a first end of the resin, wherein the thickness of the heat sink is no greater than 35% of the thickness of the device.