Flip-Chip Package Structure With CTE-Matched Thermal Layer
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Solution Overview
Problem
Flip-chip devices face challenges in thermal management due to limited primary heat paths through interconnects, leading to difficulties in effectively directing heat away from the devices while maintaining structural integrity of the packages.
Innovation Solution
The implementation of a package structure that includes a base layer for electrical interconnection and a thermally conductive layer for heat dissipation, with a coefficient of thermal expansion (CTE) matching between the base and thermally conductive layers to maintain structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flip-chip device uses traditional interconnect structures for electrical connection, then the number of connections can be increased for a given die size, but the primary heat path through the interconnects becomes limited and temperature control becomes difficult
Solution Approach 1:
The patent segments the heat dissipation function from the electrical interconnect function by introducing a separate thermally conductive layer. The interconnect structure (solder bumps/pillars) handles electrical connections, while the thermally conductive layer (with high thermal conductivity material) handles heat dissipation. This segmentation allows independent optimization of both electrical connectivity and thermal management.
Solution Approach 2:
The patent introduces a thermally conductive layer as an intermediary between the flip-chip device and the heat sink. This intermediate layer provides a dedicated thermal pathway that mediates heat transfer from the device, separating the thermal management function from the electrical interconnect structure and enabling effective heat dissipation without compromising electrical connection density.
2Adaptability or versatility
If multiple devices are included in a single package to provide more complex electrical systems, then functionality increases, but the risk of package warping due to CTE mismatches increases
Solution Approach 1:
The patent changes the thermal conductivity parameter of the package structure by introducing a thermally conductive layer with high thermal conductivity. This parameter change enables more uniform heat distribution across the package, reducing thermal gradients and their associated stresses. The modified thermal parameter helps compensate for CTE mismatches between different materials in the multi-device package, reducing warping risk.
3Adaptability or versatility
If the primary heat path is limited through interconnects in flip-chip devices, then electrical connection density can be maximized, but effective heat channeling away from devices becomes difficult
Solution Approach 1:
The patent segments the heat dissipation function from the electrical interconnect structure by introducing a separate thermally conductive layer. The interconnect structure (solder bumps/pillars) handles electrical connections, while the thermally conductive layer (with high thermal conductivity material) handles heat dissipation. This segmentation allows independent optimization of both electrical connectivity and thermal management.
Solution Approach 2:
The thermally conductive layer serves multiple functions: it acts as a heat spreader to distribute heat from the flip-chip device, provides a thermal pathway to the heat sink, and serves as part of the package structure. This multi-functionality enables effective heat dissipation while maintaining electrical connection density, addressing both thermal management and electrical connectivity requirements.
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 enhances thermal management by effectively channeling heat away from flip-chip devices, reducing the risk of package warping and maintaining structural integrity across varying operating conditions.
Implementation Method 1
a thermally conductive layer positioned so that the plurality of devices are located between the base layer and the thermally conductive layer, wherein the flip-chip is thermally connected to the thermally conductive layer
Implementation Method 2
a coefficient of thermal expansion (CTE) of the thermally conductive layer is approximately the same as the base layer, and wherein the CTE of the flip-chip is not approximately the same as the CTE of the thermally conductive layer or the CTE of the base layer
Data Source
AI summary
An integrated circuit package is provided. According to some aspects, the integrated circuit package includes a plurality of devices comprising a flip-chip having an active side. The package further includes a base layer configured to electrically interconnect the plurality of devices, wherein the active side of the flip-chip is positioned opposite the base layer and is electrically connected to the base layer; and a thermally conductive layer positioned so that the plurality of devices are located between the base layer and the thermally conductive layer, wherein the flip-chip is thermally connected to the thermally conductive layer. In some embodiments, a coefficient of thermal expansion (CTE) of the thermally conductive layer is approximately the same as the base layer, and wherein the CTE of the flip-chip is not approximately the same as the CTE of the thermally conductive layer or the CTE of the base layer.