PoP Thermal Transfer via High-Conductivity Mold Compound
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Solution Overview
Problem
Package-on-package (PoP) semiconductor packages face challenges with heat dissipation due to reduced thermal transfer, leading to hot spots and premature failure, as conventional methods like capillary underfill systems require larger gaps and are inefficient in heat distribution.
Innovation Solution
A method involving a high thermal conductivity mold compound is used to fill the gap between stacked semiconductor packages, enhancing heat distribution and removal by flowing a material into the gap between the packages, allowing for smaller gaps and improved thermal conductivity in the z-direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional capillary underfill systems are used to fill gaps between stacked semiconductor packages, then the packages can be physically coupled, but the gap size must be larger and thermal conductivity is reduced
Solution Approach 1:
The patent changes the material parameters by using a mold compound with higher thermal conductivity and different flow characteristics compared to conventional capillary underfill materials. This allows the material to effectively fill smaller gaps while providing superior thermal conduction pathways from the first package to the second package, resolving the contradiction between gap size reduction and heat dissipation maintenance.
Solution Approach 2:
The patent employs a composite mold compound formulation that combines materials with high thermal conductivity properties. This composite material achieves both the mechanical function of filling and coupling packages and the thermal function of conducting heat efficiently, thereby resolving the contradiction between structural coupling and thermal management in reduced-gap PoP configurations.
2Length of stationary object
If smaller gaps are used between stacked packages to reduce z-height, then package density increases, but thermal transfer is reduced leading to hot spots
Solution Approach 1:
The patent modifies the thermal conductivity parameter of the gap-filling material by selecting a mold compound with superior thermal conduction properties. This parameter change enables effective heat transfer through the reduced gap distance, maintaining reliability while achieving smaller z-height dimensions for higher package density.
Solution Approach 2:
The mold compound acts as an intermediary material between the stacked packages, providing both mechanical support and thermal conduction pathways. This intermediary substance bridges the thermal gap created by reduced physical distance, ensuring continuous heat flow from the first package through the gap to the second package, thus preventing hot spots while maintaining compact z-height.
3Temperature
If mold compound is flowed into the gap between packages, then thermal conductivity is enhanced, but the process complexity increases
Solution Approach 1:
The patent applies a multi-functional mold compound that simultaneously provides mechanical coupling, gap filling, and thermal conduction. This universal material eliminates the need for separate thermal interface materials or complex multi-step assembly processes, thereby enhancing thermal conductivity without proportionally increasing manufacturing process complexity.
Solution Approach 2:
The patent merges the functions of structural support and thermal management into a single mold compound application step. By combining these functions into one material and one processing operation, the patent achieves enhanced thermal conductivity while avoiding the complexity increase that would result from adding separate thermal management steps to the manufacturing process.
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 provides more uniform heat spreading, increased thermal conductivity, reduced z-height of the PoP package, and higher package density, effectively preventing hot spots and extending the package's lifespan by improving heat dissipation.
Implementation Method 1
improve heat distribution across the upper surface of the first semiconductor package and improve the conduction of heat from the first semiconductor package to the second semiconductor package
Data Source
AI summary
Systems and methods for improving heat distribution and heat removal efficiency in PoP semiconductor packages are provided. A PoP semiconductor package includes a first semiconductor package that is physically, communicably, and conductively coupled to a stacked second semiconductor package. A gap forms between the upper surface of the first semiconductor package and the lower surface of the second semiconductor package. Additionally, interstitial gaps form between each of the PoP semiconductor packages disposed on an organic substrate. A curable fluid material, such as a molding compound, may be flowed both in the interstitial spaces between the PoP semiconductor packages and into the gap between the upper surface of the first semiconductor package and the lower surface of the second semiconductor package.