Package-on-Package Underfill Sidewall Protection and Curing
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving high integration density and reliable packaging techniques for semiconductor dies, particularly in Package-on-Package (PoP) technology, where existing underfill processes are limited by low pressure curing and slow void movement, affecting package reliability and singulation efficiency.
Innovation Solution
A full coverage underfill process is introduced, which involves curing the underfill at higher pressures to accelerate void movement and improve throughput, and includes a redistribution structure with multiple dielectric and metallization layers to enhance package protection and singulation simplicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If underfill is cured at low pressure, then package reliability is maintained, but void movement is slow and throughput is reduced
Solution Approach 1:
The patent changes the pressure parameter during underfill curing from low pressure to high pressure (e.g., 5-20 psi or higher). This parameter change accelerates void movement through the underfill material, significantly improving throughput while the controlled pressure application ensures reliable package formation without compromising structural integrity
2Productivity
If conventional underfill processes are used, then processing is simpler, but sidewall protection is insufficient and singulation efficiency is reduced
Solution Approach 1:
The patent applies underfill material to the sidewalls of semiconductor packages before the final curing process. This preliminary action provides protective coverage that simplifies subsequent singulation operations, as the pre-applied underfill reduces the need for complex post-processing steps to protect or handle fragile sidewalls
Solution Approach 2:
The underfill application is segmented into specific regions - primarily targeting sidewall areas that require protection. This selective segmentation allows the process to focus complexity only where needed (sidewall protection zones) while leaving other areas simpler, thereby improving singulation efficiency without uniformly increasing overall process 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 enhanced underfill process improves package reliability, yield, and singulation efficiency by providing increased protection to sidewalls and accelerating the underfill curing process, allowing for higher integration density and more efficient processing.
Implementation Method 1
an underfill between the first package and the second package and surrounding the first set of conductive connectors, the underfill having a first portion extending up along a sidewall of the second package
Implementation Method 2
The underfill may be cured under a higher pressure than other underfill processes. This increase in pressure may accelerate the movement of voids in the underfill during the curing process
Data Source
AI summary
An embodiment is a structure including a first package including a first die, and a molding compound at least laterally encapsulating the first die, a second package bonded to the first package with a first set of conductive connectors, the second package comprising a second die, and an underfill between the first package and the second package and surrounding the first set of conductive connectors, the underfill having a first portion extending up along a sidewall of the second package, the first portion having a first sidewall, the first sidewall having a curved portion and a planar portion.