Semiconductor Package Top Layer for Heat Dissipation Without CTE Mismatch
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Solution Overview
Problem
Modern electronic devices require high power density and improved thermal performance, but increasing the thermal conductivity of epoxy molding compounds (EMC) can mismatch the thermal coefficient of expansion (TCE) with other structures, affecting device reliability and manufacturability, and existing testing methods are lengthy and inefficient.
Innovation Solution
Incorporating a thermally conductive layer with a higher thermal conductivity molding compound on the semiconductor die, which does not interface with the substrate or other structures, allowing for enhanced heat dissipation without altering the CTE matching, thus facilitating improved thermal performance without extensive requalification testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thermal conductivity of the epoxy molding compound (EMC) is increased to improve thermal performance, then heat dissipation is enhanced, but the thermal coefficient of expansion (TCE) mismatches with substrates and lead frames, adversely affecting device reliability and manufacturability
Solution Approach 1:
The patent divides the molding compound into two distinct segments: a first molding compound for the package structure with standard thermal properties and TCE matching characteristics, and a second thermally conductive molding compound for the thermally conductive layer with high thermal conductivity. This segmentation allows each material to be optimized for its specific function without compromise.
Solution Approach 2:
The patent applies local quality by placing the high thermal conductivity molding compound specifically in the thermally conductive layer where heat dissipation is most critical, while the surrounding package structure uses standard molding compound with matched TCE. This localized application of enhanced thermal properties achieves thermal performance improvement without introducing TCE mismatch issues in the overall package structure.
2Temperature
If a high thermal conductivity molding compound is used throughout the package structure, then thermal performance is improved, but extensive requalification testing is required to ensure manufacturability and reliability
Solution Approach 1:
The patent segments the molding compound application so that only the thermally conductive layer uses the high thermal conductivity material, while the rest of the package structure uses standard material. This segmentation allows the majority of the package structure to maintain proven compatibility with existing manufacturing processes and reliability standards, minimizing the scope of requalification testing required.
Solution Approach 2:
The patent introduces a thermally conductive layer as an intermediary element between the semiconductor die and the external environment. This layer acts as a dedicated thermal management component that can be optimized independently from the package structure, allowing thermal performance enhancement without requiring comprehensive requalification of the entire package assembly.
3Temperature
If the TCE of the molding compound is changed to improve thermal conductivity, then heat dissipation is enhanced, but mismatches with substrates and lead frames cause adverse effects on component and board level reliability
Solution Approach 1:
The patent segments the molding compound into two functional regions: the package structure using material with TCE matched to substrates and lead frames, and the thermally conductive layer using material with superior thermal conductivity. This segmentation isolates the TCE mismatch issue to a localized region that does not directly interface with critical structures.
Solution Approach 2:
The patent applies local quality by confining the high thermal conductivity material with potentially different TCE properties to the thermally conductive layer, which is positioned away from direct interfaces with substrates and lead frames. The surrounding package structure maintains TCE compatibility, eliminating harmful TCE mismatch effects while preserving thermal performance benefits.
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 approach enhances thermal performance and reliability while maintaining CTE matching, reducing thermal resistance and mechanical stress, and minimizing the need for extensive requalification testing, thus improving component and board level reliability and manufacturability.
Implementation Method 1
the thermally conductive layer includes a second molding compound having a second thermal conductivity that is greater than the first thermal conductivity
Data Source
AI summary
An electronic device includes: a semiconductor die having opposite first and second sides and a conductive terminal along the first side; a conductive lead electrically coupled to the conductive terminal; a package structure that forms a top side of the electronic device and encloses a portion of the semiconductor die, the package structure including a first molding compound having a first thermal conductivity; and a thermally conductive layer on at least a portion of the second side of the semiconductor die, the thermally conductive layer including a second molding compound having a second thermal conductivity that is greater than the first thermal conductivity.