Mold Trench Structure for IC Package Warpage Relief
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Solution Overview
Problem
The challenge of IC package warpage due to mismatched coefficients of thermal expansion (CTE) between dies and encapsulating mold materials, exacerbated by miniaturization demands and higher soldering temperatures, leads to issues like poor solder joints, yield losses, and increased costs in heterogeneous packages.
Innovation Solution
Incorporating trenches in the mold material surrounding the dies to relieve thermal stress, which are designed to expand and counteract warpage, thereby maintaining package flatness and improving assembly reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional mold material is used without trenches, then the package structure is simple and easy to manufacture, but thermal stress causes warpage and reliability issues
Solution Approach 1:
The mold material is segmented by introducing trenches that divide the continuous mold material into separate regions. These trenches create discrete stress management zones that allow differential thermal expansion without causing overall package warpage, thus improving reliability while maintaining manufacturing feasibility.
Solution Approach 2:
The trenches act as intermediary stress-relief elements between the die and the surrounding mold material. They provide a controlled interface that absorbs and redistributes thermal stress, preventing direct stress transmission that would cause warpage and reliability issues.
2Volume of moving object
If miniaturization is pursued to meet demand, then device size is reduced, but warpage and stress issues are exacerbated
Solution Approach 1:
The trench structure introduces local variations in the mold material properties at strategic locations around the die. These localized features create stress management zones that compensate for the reduced overall device size, maintaining adequate stress relief and flatness even as the device is miniaturized.
3Ease of manufacture
If higher soldering temperatures are used, then soldering process is improved, but thermal stress and warpage increase
Solution Approach 1:
The trenches are pre-formed in the mold material before the soldering process. This beforehand structural preparation creates stress accommodation zones that cushion against the thermal stress generated during high-temperature soldering, allowing improved soldering processes without exacerbating warpage issues.
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 introduction of trenches in the mold material effectively reduces warpage, enhancing the flatness and reliability of IC packages, leading to improved solder joint quality and reduced yield losses, thus addressing the cost and performance issues associated with package warpage.
Implementation Method 1
mold material with a stress-relief trench... designed to expand and counteract warpage
Data Source
AI summary
Disclosed herein are microelectronic assemblies, as well as related apparatuses and methods. In some embodiments, a microelectronic assembly may include a first die having a first surface, an opposing second surface, and a first footprint; a second die electrically coupled to the second surface of the first die and having a second footprint, wherein the second footprint is smaller than the first footprint; and a mold material on the second surface of the first die and surrounding the second die, the mold material including a trench.