Die Preform Grooves for Solder Void Reduction
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Solution Overview
Problem
Solder voids often form during the attachment of semiconductor dies to substrates due to the non-wettability of solder-to-die backside metal, particularly around vias, leading to trapped air and reduced solder flow, which can result in voids and increased thermal resistance.
Innovation Solution
The introduction of grooves extending from vias to the edges of the die or die-attach preforms, allowing air or gas to escape during solder reflow, thereby preventing void formation. These grooves can be intersecting, u-shaped, or spiral, and are designed to facilitate the flow of air or gas, ensuring that the solder can fill the area without trapping air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is used to attach dies to substrates, then bonding is achieved, but solder voids form due to non-wettability and trapped air around vias
Solution Approach 1:
The patent extracts the trapped air from the solder joint area by creating grooves that extend from vias to edges, allowing air to escape during reflow. This removes the harmful factor (air) that causes void formation, thereby improving bonding quality without sacrificing reliability
Solution Approach 2:
The patent segments the solder joint area by introducing grooves that divide the space around vias. This segmentation creates escape paths for air bubbles, preventing them from aggregating into large voids. The grooves segment the harmful air pockets into smaller, manageable sections that can be evacuated
2Reliability
If air is trapped around vias during solder reflow, then air expands at elevated temperatures, but this limits solder flow and creates voids
Solution Approach 1:
The patent performs preliminary action by pre-forming grooves in the die or preform before solder attachment. These grooves are预先 designed to provide air escape paths during reflow, preventing air trapping before it becomes a problem. The grooves are created in advance to guide air flow and prevent void formation during the soldering process
3Object-affected harmful factors
If grooves are introduced to allow air escape, then void formation is prevented, but the structure becomes more complex
Solution Approach 1:
The patent applies local quality by introducing grooves only in specific locations where vias are present and void formation is most problematic. The grooves are not applied uniformly across the entire die surface but are localized to areas needing air escape paths. This targeted approach reduces overall structural complexity while effectively preventing voids
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 effectively reduces the occurrence of solder voids, enhancing the bonding quality and reducing thermal resistance, particularly beneficial for high-power applications where voids can lead to device failure.
Implementation Method 1
allowing air or gas to escape during solder reflow
Implementation Method 2
the solder material may flow into the grooves, filling the grooves and at least partially filling the voids
Implementation Method 3
During solder reflow at elevated temperatures, the air around the vias expands, limiting the flow of solder to the area around the vias
Data Source
AI summary
Embodiments include but are not limited to apparatuses and systems including a die or a preform including at least one groove configured to extend from at least one via of the die to an edge of the die. Other embodiments may be described and claimed.