Selective Underfill Application for Solder Joint Reliability
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Solution Overview
Problem
Conventional methods for applying underfill material in packaging and substrates often result in excessive material consumption and unreliable solder joints, especially under thermal stress or drop tests, due to the full encasement of solder balls.
Innovation Solution
Selective application of underfill material in specific areas between packages and substrates, such as corners or peripheries, to enhance solder joint reliability while reducing material usage, using methods like screen printing or dispensing, and curing the underfill simultaneously with solder reflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire area between the package and the substrate is filled with underfill material, then solder joint reliability is improved, but underfill material consumption increases
Solution Approach 1:
The patent applies underfill material selectively in specific regions (such as corners or areas with higher stress concentration) rather than uniformly across the entire area between package and substrate. This localized application strategy provides enhanced solder joint reliability in critical areas while significantly reducing overall underfill material consumption.
Solution Approach 2:
The patent employs partial action by applying underfill material only to necessary regions rather than the complete area. The underfill is applied in controlled amounts to specific zones where it provides the most benefit, avoiding the waste associated with full-area application while still achieving adequate solder joint protection.
2Reliability
If underfill material is applied to the entire area between package and substrate, then solder joint reliability is improved, but manufacturing complexity increases
Solution Approach 1:
By applying underfill material only to specific regions rather than the entire area, the patent simplifies the manufacturing process. The selective application reduces material handling complexity, decreases curing time for smaller areas, and allows for more efficient production workflows while maintaining solder joint reliability in critical zones.
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 underfill material consumption while maintaining solder joint reliability by strategically placing underfill material in areas prone to failure, thereby improving thermal cycling and drop test performance.
Implementation Method 1
an underfill is drawn by capillary action into the area between the package and the substrate or other package
Implementation Method 2
no-flow underfill material has been applied directly to the substrate or other package, and then the package is pressed onto the underfill
Implementation Method 3
a package is mounted to a substrate (or joined with another package) by reflowing solder bumps between the package and the substrate or other package
Data Source
AI summary
Embodiments include but are not limited to apparatuses and systems including semiconductor packages, e.g. memory packages, having a substrate or a first package, and a second package coupled to the substrate or the first package, wherein the second package includes at least one die and an underfill material disposed in a portion, but not an entirety, of an area between the package and the substrate or the first package. Other embodiments may be described and claimed.