3DIC Package Thermal Path Design for Hot Spot Dissipation
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Solution Overview
Problem
Three-Dimensional Integrated Circuits (3DICs) face challenges in heat dissipation due to non-conductive materials like underfill and molding compound between stacked dies, leading to localized temperature peaks (hot spots) that affect electrical performance and reliability.
Innovation Solution
The implementation of a package with efficient hot spot thermal management features, including a substrate with conductive layers and vias, a high thermal conductivity material, and a contour ring/cover to dissipate heat away from the die stack, utilizing exposed conductive layers for thermal and electrical connections, and a thermal interface material to enhance heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If stacked dies are bonded through bonding to form 3DICs, then integration density is improved, but heat dissipation capability deteriorates due to non-conductive materials trapping heat in inner regions
Solution Approach 1:
The patent segments the thermal management function by introducing separate thermal vias and heat dissipation structures that are distinct from the electrical interconnect structures. This allows independent optimization of thermal pathways without compromising the stacked die integration architecture.
Solution Approach 2:
The patent introduces thermal interface materials and heat spreader layers as intermediary structures between the stacked dies and the heat dissipation system. These intermediaries facilitate efficient heat transfer from the inner dies through the non-conductive underfill and molding compound regions to the external heat sinks.
2Strength
If non-conductive materials like underfill and molding compound are used between stacked dies, then structural support and encapsulation are improved, but thermal conductivity deteriorates causing hot spots
Solution Approach 1:
The patent employs composite material structures combining non-conductive underfill and molding compound with embedded conductive thermal pathways. The composite structure maintains the structural integrity and encapsulation benefits of the non-conductive materials while introducing thermal conduction channels through vias and heat spreaders to prevent hot spot formation.
3Temperature
If heat is trapped in inner region of bottom stacked die, then localized temperature peaks (hot spots) are formed, but electrical performance and reliability of overlaying devices deteriorate
Solution Approach 1:
The patent extracts heat from the inner regions of stacked dies by creating dedicated thermal vias that extend from the inner die interfaces through the underfill and molding compound to external heat dissipation structures. This extraction mechanism removes the harmful thermal accumulation that would otherwise degrade the electrical performance and reliability of overlaying devices.
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 effectively reduces hot spots by conducting heat to peripheral areas, minimizing their impact on overlaying devices and improving the thermal and electrical performance of the 3DIC package, with reduced maximum operation temperatures from 96.1°C to 90.1°C for the bottom die and 93.3°C to 89.3°C for top dies.
Implementation Method 1
a high thermal conductivity material is disposed over the substrate and contacts the exposed portion of the conductive layer
Data Source
AI summary
A package includes a substrate having a conductive layer, and the conductive layer comprises an exposed portion. A die stack is disposed over the substrate and electrically connected to the conductive layer. A high thermal conductivity material is disposed over the substrate and contacting the exposed portion of the conductive layer. The package further includes a contour ring over and contacting the high thermal conductivity material.