Solder Cavity Interconnects for Bridging and Cracking Prevention
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Solution Overview
Problem
Current microelectronic packaging technologies face challenges in increasing interconnection density and reliability, particularly due to issues like bridging and cracking failures in solder connections, which affect the performance and cost-effectiveness of smaller microelectronic devices.
Innovation Solution
The formation of cavities with sloped sidewalls in a dielectric layer on a substrate, allowing for the deposition and reflow of solder paste to create solder structures that can form interconnects with either contact lands on the same or another substrate, enhancing connection reliability and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional flat solder connections are used, then the manufacturing process is simple, but bridging and cracking failures occur reducing reliability
Solution Approach 1:
The solder connection is segmented into multiple components: a solder structure with a base portion on the first substrate, a cavity portion extending from the base, and a bridge portion spanning to the second substrate. This segmentation allows the solder to accommodate thermal stress and mechanical loading separately in each region, preventing bridging and cracking failures while maintaining connection reliability.
Solution Approach 2:
The invention transitions from a traditional two-dimensional flat solder connection to a three-dimensional structure with vertical and horizontal extensions. The cavity portion extends downward from the base, and the bridge portion extends horizontally to the second substrate, creating a spatial configuration that reduces stress concentration and prevents failures.
2Productivity
If interconnection pitch is reduced to increase density, then more connections fit in smaller area, but bridging failures increase
Solution Approach 1:
The solder structure is divided into distinct functional segments: a base portion for attachment to the first substrate, a cavity portion that provides structural support and stress relief, and a bridge portion for connection to the second substrate. This segmentation allows each part to be optimized for its specific function, enabling higher density while preventing bridging failures.
Solution Approach 2:
The cavity portion acts as an intermediary element between the base portion and the bridge portion. It provides a transition zone that accommodates thermal expansion and mechanical stress, preventing direct stress transmission that would cause bridging failures in high-density configurations.
3Weight of moving object
If solder joint size is reduced for smaller devices, then device size decreases, but cracking failures increase
Solution Approach 1:
The solder joint is designed with three-dimensional geometry including a base portion with a first area on the first substrate, a cavity portion extending from the base, and a bridge portion with a second area on the second substrate. This vertical and horizontal expansion within a compact footprint increases the effective bonding area and structural strength without increasing the device's overall footprint, preventing cracking failures in miniaturized devices.
Solution Approach 2:
The solder structure functions as a composite configuration combining different geometric forms (base, cavity, and bridge portions) with potentially different material properties or microstructures optimized for each region. The base portion provides attachment strength, the cavity portion provides stress relief, and the bridge portion provides connection strength, collectively preventing cracking failures.
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 bridging and cracking failures, allows for smaller interconnection pitch, and improves the reliability and strength of solder joints, particularly under lateral loading, thereby enabling more efficient and cost-effective microelectronic device manufacturing.
Implementation Method 1
allowing for the deposition and reflow of solder paste to create solder structures
Data Source
AI summary
The present disclosure relates to the field of fabricating microelectronic packages, wherein cavities are formed in a dielectric layer deposited on a first substrate to maintain separation between soldered interconnections. In one embodiment, the cavities may have sloped sidewalls. In another embodiment, a solder paste may be deposited in the cavities and upon heating solder structures may be formed. In other embodiments, the solder structures may be placed in the cavities or may be formed on a second substrate to which the first substrate may be connected. In still other embodiments, solder structures may be formed on both the first substrate and a second substrate. The solder structures may be used to form solder interconnects by contact and reflow with either contact lands or solder structures on a second substrate.