Multi-Die Package Layout Using Non-Active Dies for CTE Stress Relief
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Solution Overview
Problem
Multi-die packages experience stress and strain due to coefficient of thermal expansion (CTE) mismatch, leading to warpage, bending, and cracking, which can cause physical damage and failure.
Innovation Solution
Incorporating non-active dies between active IC dies to reduce the amount of encapsulant material and increase gap areas for stress absorption, distributing stress and strain more evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If encapsulant material is used to fill gaps between IC dies, then the IC dies are protected and held in place, but stress and strain accumulate due to CTE mismatch causing warpage and cracking
Solution Approach 1:
A non-active die is introduced as an intermediary component between active IC dies. This non-active die has a CTE that matches the encapsulant material, serving as a buffer that reduces stress concentration at the interfaces between active dies and encapsulant, thereby preventing warpage and cracking while maintaining structural integrity
Solution Approach 2:
The CTE parameter of the die structure is modified by incorporating a non-active die with specific material properties. This non-active die has a CTE matched to the encapsulant material, creating a gradient transition that reduces the overall CTE mismatch in the package structure and minimizes thermal stress
2Reliability
If non-active dies are added to the package, then stress absorption area increases and CTE mismatch is minimized, but device complexity increases
Solution Approach 1:
The non-active die is designed as a sacrificial or passive component that does not require complex interconnections or active circuitry. It serves purely as a mechanical buffer and stress distributor, simplifying its design and reducing overall package complexity despite adding another die to the structure
3Reliability
If non-active dies are positioned between active IC dies, then gap areas for stress absorption increase, but manufacturing precision requirements increase
Solution Approach 1:
The non-active die is positioned to create equipotential stress distribution zones between active IC dies. By strategically placing this buffer die in high-stress regions, the package achieves more uniform stress distribution across the structure, reducing peak stress concentrations and improving overall reliability
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
Reduces the likelihood of warpage, bending, and cracking, enhancing the reliability and yield of the multi-die package by minimizing CTE mismatch.
Implementation Method 1
The gaps may provide areas in the multi-die package that absorb stress and strain experienced by the multi-die package
Implementation Method 2
A CTE mismatch may occur, for example, between the IC dies and the encapsulant material and/or the underfill material. The high magnitudes of stress resulting from CTE mismatch(es) in the multi-die package may cause warpage, bending, and/or cracking
Data Source
AI summary
A multi-die package includes a plurality of non-active dies among the IC dies included in the multi-die package. The non-active dies may be included to reduce the amount of encapsulant material and/or an underfill material that is used in the multi-die package, which reduces the amount of CTE mismatch in the multi-die package. Moreover, a plurality of non-active dies may be positioned in an adjacent manner between two or more active IC dies. The use of a plurality of non-active dies in a particular area of the multi-die package increases the quantity of gaps in the multi-die package. The increased quantity of gaps in the multi-die package provides an increased amount of area in the multi-die package for stress and strain absorption, and enables more even distribution of stresses and strains in the multi-die package.