Flip Chip Thermal Interposer for Heat Dissipation
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Solution Overview
Problem
Existing packaging methods for flip chip mounted semiconductor devices in molded device packages are inefficient in thermal dissipation, particularly for power transistors that generate substantial heat, as the semiconductor die is isolated from the system board by mold compound and ambient atmosphere, leading to inadequate heat transfer.
Innovation Solution
Incorporating a thermal interposer made of thermally conductive material, such as silicon, positioned over the backside surface of the semiconductor die and in thermal contact with it, which is then encapsulated in mold compound along with the semiconductor die and post connects, allowing for enhanced thermal transfer through exposed surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the semiconductor die is isolated from the system board by mold compound and ambient atmosphere, then the package structure is simple and easy to manufacture, but the thermal dissipation performance deteriorates
Solution Approach 1:
A thermal management component is introduced as an intermediary element between the semiconductor die and the system board. This component includes a thermally conductive layer in thermal contact with the backside of the semiconductor die, and a thermally conductive member extending through the mold compound to contact the system board, thereby mediating heat transfer without compromising package simplicity
Solution Approach 2:
The thermal management solution is segmented into distinct functional layers: a thermally conductive layer directly contacting the semiconductor die backside, a thermally conductive member extending through the mold compound, and connection elements that interface with the system board. This segmentation allows each component to be optimized for its specific function while maintaining overall package simplicity
2Device complexity
If the semiconductor die is isolated from the system board by mold compound and ambient atmosphere, then the package structure is simple, but the heat transfer efficiency deteriorates
Solution Approach 1:
Thermal management components serve as intermediaries to bridge the thermal gap created by the mold compound and ambient atmosphere. The thermally conductive layer and thermally conductive member create a dedicated heat transfer pathway that bypasses the thermal resistance of the isolating materials
Solution Approach 2:
The package structure incorporates composite material solutions including thermally conductive materials integrated within the mold compound matrix, and hybrid construction combining different thermally conductive materials (such as metal traces, ceramic layers, or polymer-based thermally conductive compounds) to achieve optimal heat transfer while maintaining structural integrity
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 significantly improves thermal dissipation by providing an efficient thermal transfer path from the semiconductor die to the printed circuit board, enhancing the thermal performance of packaged devices by up to 65% compared to traditional methods.
Implementation Method 1
a thermal interposer made of thermally conductive material, such as silicon, positioned over the backside surface of the semiconductor die and in thermal contact with it
Data Source
AI summary
In a described example, an apparatus includes: a package substrate having a die mount surface; semiconductor die flip chip mounted to the package substrate on the die mount surface, the semiconductor die having post connects having proximate ends on bond pads on an active surface of the semiconductor die, and extending to distal ends away from the active surface of the semiconductor die and connected to the package substrate by solder joints; a thermal interposer comprising a thermally conductive material positioned over and in thermal contact with a backside surface of the semiconductor die; and mold compound covering a portion of the package substrate, a portion of the thermal interposer, the semiconductor die, and the post connects, the thermal interposer having a surface exposed from the mold compound.