Stepped Package Lid Compression for TIM Edge Coverage
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Solution Overview
Problem
Large package assemblies face challenges in heat dissipation due to high coefficient of thermal expansion (CTE) mismatch, leading to poor thermal interface material (TIM) film coverage at the edge regions of semiconductor dies, which can result in delamination.
Innovation Solution
Incorporating a stepped package lid with either an upper or bottom step region to enhance TIM film coverage at the edge regions, providing improved thermal dissipation by ensuring uniform attachment and compression of the TIM film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large package assembly is used to accommodate multiple semiconductor dies, then the quantity of semiconductor components is improved, but heat dissipation performance deteriorates due to CTE mismatch causing poor TIM film coverage at edge regions
Solution Approach 1:
The package lid is segmented into multiple height levels through step regions, creating different elevation zones that allow selective compression of the TIM film. This segmentation enables the lid to apply differentiated pressure to different areas of the semiconductor dies, ensuring adequate TIM coverage at edge regions while maintaining overall package integrity for multi-die configurations
Solution Approach 2:
The step regions create local variations in the package lid's height and compression force distribution. Areas with step regions provide enhanced localized compression to the TIM film at critical edge regions, while other areas maintain standard compression levels, thereby improving thermal contact quality where it is most needed without compromising the entire package structure
2Ease of manufacture
If uniform compression force is applied to the TIM film across the entire package lid, then ease of manufacture is improved, but TIM film coverage at edge regions deteriorates due to CTE mismatch in large packages
Solution Approach 1:
The package lid is divided into distinct height zones using step regions, which segment the compression force distribution. This allows the manufacturing process to apply a generally uniform compression force while the step regions automatically create localized high-compression zones at edge regions, thereby maintaining manufacturing simplicity while improving TIM film coverage reliability
Solution Approach 2:
The step regions act as mechanical intermediaries that translate a relatively uniform applied compression force into differentiated local compression forces. The stepped structure mediates between the simple uniform application method and the complex differential compression requirement, achieving reliable TIM coverage without complicating the manufacturing process
3Temperature
If the package lid is designed with step regions to improve TIM film coverage, then thermal dissipation is improved, but device complexity increases
Solution Approach 1:
The step regions segment the package lid into functional zones that improve thermal dissipation through enhanced TIM compression. While this does increase structural complexity, the segmentation is achieved through relatively simple geometric modifications to the lid profile rather than complex mechanisms, providing a pragmatic balance between thermal performance and manufacturing complexity
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
The stepped package lid design improves TIM film coverage and thermal dissipation, reducing the risk of delamination and enhancing the overall thermal management of large package assemblies.
Implementation Method 1
the TIM film may be compressed between the step region and the edge region of the interposer module
Data Source
AI summary
A package assembly includes an interposer module on a package substrate, a thermal interface material (TIM) film on the interposer module, and a package lid that includes a plate portion on the TIM film and a step region projecting away from the plate portion and located over the TIM film and over an edge region of the interposer module.