Underfill Flow Barriers for Void-Free Die Package Assembly
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In the manufacturing of package assemblies, the uneven flow of underfill between a substrate and dies often results in voids, leading to reduced yield and compromised thermomechanical performance due to differences in flow rates along the edges and centers, which existing methods struggle to address effectively, especially in complex die architectures.
Innovation Solution
The use of barriers on the substrate to modulate the flow of underfill by controlling its speed, placed strategically to match edge and center flow rates, thereby preventing voids without reformulating the underfill material or degrading throughput, and facilitating unconventional epoxy dispensing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If underfill is flowed between substrate and die without barriers, then the manufacturing process is simple, but voids form due to uneven flow rates between edges and centers
Solution Approach 1:
The patent applies local quality by placing barriers at specific locations (edges and corners) of the die rather than uniformly across the entire perimeter. These strategically positioned barriers create localized flow modulation zones that address the specific problem of uneven edge flow without adding unnecessary complexity throughout the entire structure.
Solution Approach 2:
The underfill flow control is segmented into distinct regions by placing barriers at specific locations around the die perimeter. This segmentation allows independent control of flow in different areas, enabling precise management of edge versus center flow rates without treating the entire boundary as a uniform control zone.
2Reliability
If barriers are added to control underfill flow, then voids are prevented and yield increases, but device complexity and manufacturing steps increase
Solution Approach 1:
Barriers are implemented only at critical locations (edges and corners) where void formation is most likely to occur, rather than creating a continuous complex barrier structure around the entire die. This localized approach achieves the reliability improvement needed to prevent voids while minimizing the increase in device complexity.
Solution Approach 2:
The barriers are pre-formed on the substrate before die attachment and underfill application. This preliminary action allows the barriers to be integrated into the substrate structure in advance, simplifying the overall manufacturing process despite the added structural element, and ensuring proper positioning without requiring complex real-time control during assembly.
3Manufacturing precision
If barriers are used to slow edge flow, then uniform underfill distribution is achieved, but manufacturing time may increase
Solution Approach 1:
Barriers are placed only at edge and corner locations where flow velocity is highest, rather than creating a continuous barrier that would slow flow across the entire die perimeter. This localized approach provides sufficient flow modulation to achieve uniform distribution while minimizing the impact on overall manufacturing throughput.
Solution Approach 2:
The barrier structure provides more flow resistance than theoretically minimum at critical locations, ensuring that even with variations in underfill viscosity or dispensing parameters, the edge flow is adequately controlled to match center flow rates, maintaining uniform distribution without requiring excessive slowing of the entire flow process.
Data Source
AI summary
Embodiments herein relate to systems, apparatuses, or processes that include barriers, which may be referred to as flow stops, to modulate, or control, the speed of flow of an underfill between the substrate and another object on the substrate, for example one or more dies coupled with the substrate. Moderating the speed of flow of the underfill reduces the number of voids in the underfill after curing. Other embodiments may be described and/or claimed.