Localized Underfill via Substrate Mesas
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Solution Overview
Problem
The use of underfill materials in semiconductor packaging can lead to issues such as warping and buckling due to thermal expansion differences, and excess underfill can interfere with other components, necessitating improved methods for underfill localization and reduction.
Innovation Solution
A semiconductor package design featuring a substrate with mesas and cavities that localize underfill material between dies and the substrate, preventing continuous underfill formation and mitigating thermal expansion effects, while reducing the overall amount of underfill used.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If underfill material is used between dies and substrate, then adhesion and contact protection are improved, but warping and buckling occur due to thermal expansion differences
Solution Approach 1:
The substrate is segmented into multiple cavities separated by mesas, which divide the underfill material into discrete portions within each cavity. This segmentation prevents continuous underfill from causing package-wide warping while maintaining localized adhesion benefits between dies and substrate in each cavity region.
Solution Approach 2:
Underfill material is applied locally only within specific cavities rather than uniformly across the entire substrate. The mesas create distinct regions where underfill is confined, providing adhesion and contact protection only where needed, while reducing overall thermal expansion effects on the package structure.
2Reliability
If underfill material is used to protect contacts, then contact protection is improved, but excess underfill interferes with other components
Solution Approach 1:
The substrate surface is divided into multiple cavities by mesas, creating discrete containment regions. Underfill material is confined to these individual cavities, ensuring it protects contacts within each cavity while preventing excess underfill from spreading to interfere with adjacent components or structures.
Solution Approach 2:
The mesas are extracted or removed from the substrate surface to create cavities, which then serve as containment structures for the underfill material. This extraction creates physical barriers that prevent underfill from spreading beyond the intended contact protection zones, eliminating interference with other components.
3Reliability
If underfill material is applied extensively, then contact protection and adhesion are improved, but the overall amount of underfill increases causing more thermal expansion issues
Solution Approach 1:
The substrate is divided into multiple cavities separated by mesas, which segment the underfill application into discrete, controlled portions. This segmentation reduces the total quantity of underfill material needed compared to extensive uniform application, while maintaining adequate contact protection and adhesion within each cavity region.
Solution Approach 2:
Underfill material is applied locally only within specific cavity regions rather than extensively across the entire substrate. The mesas define precise boundaries for local underfill application, providing necessary contact protection and adhesion only where contacts exist, thereby minimizing the overall quantity of underfill material required.
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 design effectively reduces the likelihood of warping and buckling, minimizes underfill interference with other components, and optimizes underfill distribution, enhancing the structural stability and thermal management of semiconductor packages.
Implementation Method 1
The underfill material is localized into a plurality of regions using the mesas
Implementation Method 2
The use of underfill materials in semiconductor packaging can lead to issues such as warping and buckling due to thermal expansion differences
Data Source
AI summary
A device and method for localizing underfill includes a substrate, a plurality of dies, and underfill material. The substrate includes a plurality of contacts and a plurality of cavities separated by a plurality of mesas. The plurality of dies is mounted to the substrate using the plurality of contacts. The underfill material is located between the substrate and the dies. The underfill material is localized into a plurality of regions using the mesas. Each of the contacts is located in a respective one of the cavities. In some embodiments, the substrate further includes a plurality of channels interconnecting the cavities. In some embodiments, the substrate further includes a plurality of intra-cavity mesas for further localizing the underfill material. In some embodiments, outer edges of a first one of the dies rest on first mesas located on edges of a first one of the cavities.