Flip-Chip Joint Pad and Pillar Structure for Extreme Fine Pitch
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The increasing functionality of ICs in electronic devices necessitates more power and signal connections to PCBs, but existing connectors with large conductive pads on ICs and substrates face reliability issues due to reduced solder volume, leading to potential bridging or low resistance to failure when trying to increase signal density.
Innovation Solution
The design incorporates copper pillars and nickel rings/collars with capillaries to increase solder volume within the FC joint, allowing for smaller pad sizes while controlling solder distribution to prevent bridging and enhance connection reliability, enabling higher signal density by reducing the likelihood of solder spreading outside the connection interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the conductive pads on ICs and substrates are made smaller to increase signal density, then the number of connections per unit area increases, but the solder volume decreases leading to reduced joint reliability and increased risk of bridging
Solution Approach 1:
The patent transitions from two-dimensional pad layouts to three-dimensional vertical structures by forming cavities within the conductive pads and filling them with solder. This vertical dimension allows increased solder volume without increasing pad footprint, thereby maintaining joint reliability while enabling smaller pad sizes for higher connection density.
Solution Approach 2:
The patent implements nested structures by placing cavities within conductive pads, and further nesting solder material within those cavities. This nested arrangement maximizes the use of vertical space, allowing additional solder volume to be contained within the existing pad footprint, thus preventing bridging while supporting reduced pad sizes.
2Productivity
If the conductive pads are made smaller to accommodate more connections, then signal density increases, but the amount of solder available to prevent bridging decreases
Solution Approach 1:
By introducing vertical cavities within the conductive pads and filling them with solder, the patent creates a three-dimensional solder reservoir. This allows the solder to be contained vertically within the pad structure, preventing lateral spreading and bridging between adjacent connections while maintaining adequate solder volume for reliable joints.
Solution Approach 2:
The nested cavity structure within the conductive pad creates a contained space for solder material. This nested arrangement ensures that solder is confined to specific vertical regions within each pad, preventing it from spreading to adjacent pads and causing bridging, while still providing sufficient solder volume for reliable electrical connections.
3Reliability
If traditional large conductive pads are used, then solder joint reliability is maintained, but the number of connections per unit area is limited
Solution Approach 1:
The patent adds a vertical dimension to the conductive pad structure by forming cavities that extend downward from the pad surface. This allows the effective solder volume to be increased without increasing the horizontal pad footprint, enabling smaller pads to be used for higher density connections while maintaining reliability through adequate solder volume.
Solution Approach 2:
By nesting cavities within the conductive pads and filling them with solder, the patent creates a compact three-dimensional structure that maximizes solder volume within the available space. This nested configuration allows smaller pad footprints to accommodate the same or greater solder volume, enabling higher connection density without compromising joint reliability.
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 solution allows for a significantly higher number of connections per unit area, reducing the likelihood of bridging and improving solder joint reliability, enabling a 100-fold increase in connections compared to traditional designs, while accommodating misalignments and maintaining connection integrity.
Implementation Method 1
Each conductive ring includes a capillary formed along an axis of the conductive ring. When the electronic device die is bonded to the substrate, the solder material is reflowed and flows through the capillary to form a conductive joint
Data Source
AI summary
An electronic component includes a device die and a substrate. The device die includes conductive contacts with conductive pillars conductively affixed to conductive contact. The conductive pillars include a cavity formed in an end of the conductive pillar opposite the conductive contact. The substrate includes of conductive pads that are each associated with one of the conductive contacts. The conductive pads include a conductive pad conductively affixed to the substrate, and a conductive ring situated within a cavity in the end conductive rings have a capillary formed along an axis of the conductive ring. A solder material fills the capillary of each of the conductive rings and the cavity formed in the end of the associated conductive pillars to form a conductive joint between the pillars and the conductive pads.