Spring Contact Interconnect for Thermal Stress Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor interconnects face high stresses due to decreasing C4 ball sizes and the use of lead-free materials, which can compromise reliability and thermal performance, and existing stress management methods are not entirely effective.
Innovation Solution
A MEMs-like spring interconnect structure with a beam and a cavity or compressible material below it, allowing for controlled expansion and stress relief, using a conductive material that transitions from solid to liquid at semiconductor operating temperatures for improved flexibility and reduced stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If C4 ball size is decreased to achieve higher density interconnects, then interconnect density is improved, but stress on interconnect increases
Solution Approach 1:
The patent introduces a dynamic spring contact structure that can deform elastically under stress. The spring contact includes a beam that can bend and a compressible material that can change volume, allowing the interconnect to dynamically adapt to thermal expansion and contraction forces, thereby reducing stress while maintaining high density
Solution Approach 2:
The patent changes the physical state parameter of the conductive material from solid at room temperature to liquid at operating temperatures. This phase transition allows the material to flow and redistribute under stress, reducing mechanical stress concentration while maintaining electrical conductivity
2Reliability
If lead-free materials are used to meet reliability requirements, then reliability is improved, but stress on interconnect increases
Solution Approach 1:
The patent introduces a compressible material as an intermediary between the spring contact beam and the solder connection. This intermediary layer absorbs and distributes mechanical stress, reducing the stress transmitted to the lead-free solder joint while maintaining the reliability benefits of lead-free materials
Solution Approach 2:
The patent creates a composite interconnect structure combining the spring contact beam, compressible material, and conductive material. This composite structure integrates the strengths of different materials to achieve both reliability and stress reduction
3Stress or pressure
If thermal levels are limited to manage stress, then stress on interconnect is reduced, but thermal performance deteriorates
Solution Approach 1:
The spring contact structure dynamically responds to thermal expansion and contraction by deforming elastically. The beam bends and the compressible material changes volume in response to thermal cycles, allowing the system to withstand higher operating temperatures without excessive stress accumulation
4Stress or pressure
If thermal cycles are limited to manage stress, then stress on interconnect is reduced, but reliability under thermal demand deteriorates
Solution Approach 1:
The conductive material undergoes a phase transition from solid to liquid at operating temperatures. This phase change allows the material to flow and redistribute stress during thermal cycles, maintaining reliability under thermal demand while reducing stress concentration at critical interfaces
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 stress at the interconnect joint during thermal cycles and reflow, maintaining high reliability and low manufacturing costs, while ensuring electrical continuity and mechanical flexibility.
Implementation Method 1
a compressible material below the beam
Implementation Method 2
allowing for controlled expansion and stress relief
Implementation Method 3
The conductive material is in a liquid state at manufacturing or operating temperatures of the semiconductor device. Thus, the conductive material could be a solid at room temperature and transition to a liquid state at the semiconductor's manufacturing or operating temperatures.
Data Source
AI summary
A semiconductor interconnection comprises a semiconductor device, a substrate adjacent the semiconductor device, and a plurality of spring contacts on the semiconductor device or the substrate. A plurality of solder connections are on the opposite semiconductor device or substrate. Each spring contact comprises a contact surface and a conductive material on the contact surface. Upon assembly of the semiconductor device and the substrate, the conductive material on the plurality of spring contacts makes contact with each of the plurality of solder connections. The conductive material is in a liquid state at manufacturing or operating temperatures of the semiconductor device. Thus, the conductive material could be a solid at room temperature and transition to a liquid state at the semiconductor's manufacturing or operating temperatures.