Underfill Layer Profile for Thin-Chip Package Warpage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As semiconductor chip thickness decreases, issues such as warpage during solder ball reflow processes become prevalent, affecting the reliability and mass production of semiconductor packages.
Innovation Solution
A semiconductor package design featuring stacked chips with underfill material layers having specific slope configurations and a mold layer, along with a method involving solder reflow and underfill material reflow processes to form reflowed chip bumps and underfill material layers, ensuring chip attachment and improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder balls are reflowed to attach semiconductor chip to printed circuit board, then chip attachment is achieved, but warpage occurs during the reflow process
Solution Approach 1:
The underfill material is applied to the substrate before the chip mounting process. This preliminary application of underfill material creates a supportive layer that prevents warpage during subsequent solder reflow, while still allowing the chip to be attached reliably through the solder balls.
Solution Approach 2:
The underfill material layer acts as a cushioning layer applied beforehand to compensate for the warpage that will occur during solder reflow. This cushioning effect maintains chip flatness while allowing the attachment process to proceed successfully.
2Length of moving object
If chip thickness is reduced, then device miniaturization is achieved, but warpage problems increase during solder reflow
Solution Approach 1:
The underfill material is applied to the substrate before mounting thin chips, providing immediate support that prevents warpage during solder reflow. This preliminary action enables the use of thinner chips without compromising attachment reliability.
Solution Approach 2:
The invention changes the physical state and distribution of the underfill material through controlled application and curing processes, creating a supportive matrix that maintains structural integrity of thin chips during the thermal stress of solder reflow.
3Stability of the object's composition
If underfill material is applied to prevent warpage, then chip flatness is maintained, but additional process steps are required
Solution Approach 1:
The underfill material application process is merged with the chip mounting process flow, where the underfill is applied to the substrate before chip placement. This integration allows warpage prevention to be achieved as part of the standard mounting sequence rather than as a separate additional process.
Solution Approach 2:
The underfill material serves multiple functions: it provides mechanical support to prevent warpage, acts as a adhesive layer, and provides stress relief. This multi-functionality reduces the need for separate process steps dedicated to each function.
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 solution enhances the reliability and productivity of semiconductor packages by preventing warpage and ensuring robust chip attachment, facilitating high-reliability mass production.
Implementation Method 1
the solder balls may be reflowed while applying pressure to the semiconductor chip under a temperature atmosphere in which the solder balls may be reflowed
Implementation Method 2
performing a solder reflow process and an underfill material reflow process in the process chamber to reflow the preliminary chip bumps and the non-conductive film
Data Source
AI summary
A semiconductor package and a method of forming the same are provided. The semiconductor package includes one or a plurality of chips on a substrate, bumps disposed below each of the one or plurality of chips, an underfill material layer on the substrate, on a side surface of each of the bumps, and extending to side surfaces of the one or plurality of chips, and a mold layer on the substrate and contacting the underfill material layer. The underfill material layer includes a first side portion, a second side portion on the first side portion and having a slope, steeper than a slope of the first side portion, and a third side portion on the second side portion and having a slope that is less steep than a slope of the second side portion.