Spacer-Guided Underfill Flow for Air-Pocket-Free Die Assembly
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Solution Overview
Problem
Current underfill processes for electronic circuit assemblies result in high spillage and air pockets, leading to manufacturing yield loss, increased time in removing excess underfill, and a less uniform coating due to excess underfill curing on outer surfaces, which renders assembled products unusable.
Innovation Solution
The method involves mounting spacers on a substrate to create narrower passages between electronic devices and the substrate, enhancing capillary action and reducing the volume of underfill needed, while applying a vacuum to remove air pockets and ensuring a smoother surface for coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If underfill is dispensed into the open space between electronic devices and substrate, then the electronic circuit assembly gains stability and rigidity, but spillage and air pockets occur leading to manufacturing yield loss
Solution Approach 1:
The patent divides the large open space into multiple smaller passages by placing spacers between electronic devices and the substrate. This segmentation allows underfill to flow more uniformly through controlled narrow paths, preventing air pockets and spillage while ensuring complete filling, thereby maintaining structural integrity and improving manufacturing yield
Solution Approach 2:
The patent introduces spacers as intermediary elements between the electronic devices and the substrate. These spacers create defined passages that guide underfill flow, prevent direct contact between underfill and outer surfaces (reducing spillage), and eliminate air pockets by controlling the filling process, thus resolving the contradiction between achieving proper filling and avoiding defects
2Manufacturing precision
If excess underfill is dispensed to ensure complete filling, then air pockets are reduced, but spillage increases causing manufacturing yield loss and additional removal time
Solution Approach 1:
The patent applies local quality by creating different passage widths through spacer placement - narrow controlled passages in critical areas prevent spillage while ensuring complete filling, and allows precise control of underfill distribution in different locations, achieving complete filling without excess spillage
3Area of stationary object
If underfill is dispensed in large volumes to fill open spaces, then coverage is improved, but the surface becomes non-uniform requiring removal and rework
Solution Approach 1:
The patent segments the filling process into multiple controlled passages, allowing underfill to be distributed uniformly across the coverage area. This prevents excessive underfill from pooling and creating non-uniform surfaces, eliminating the need for removal and rework while maintaining complete coverage
4Manufacturing precision
If spacers are added to create narrower passages, then underfill flow control is improved and spillage reduced, but device complexity increases
Solution Approach 1:
The patent uses spacers as simple intermediary elements that provide precise flow control without complex mechanisms. The spacers are straightforward components that create defined passages, offering excellent underfill control while adding minimal complexity to the device structure
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
This approach reduces air pockets and spillage, enhances the uniformity of the underfill flow, and minimizes the amount of excess underfill, thereby increasing manufacturing efficiency and product reliability by preventing unusable assemblies and reducing the need for repetitive manufacturing processes.
Implementation Method 1
mounting one or more spacers to the substrate at one or more positions, respectively, to form one or more passages between the one or more spacers and the one or more structures, dispensing underfill to the one or more passages
Implementation Method 2
applying a vacuum to remove air pockets
Data Source
AI summary
A method for underfilling an electronic circuit assembly may include mounting one or more structures to a substrate, mounting one or more spacers to the substrate at one or more positions, respectively, to form one or more passages between the one or more spacers and the one or more structures, dispensing underfill to the one or more passages, and curing the underfill to secure the one or more structures to the substrate. The one or more structures may include one or more dies.