Cantilever Latching Spring for Solder-Free Electrical Interconnects
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Solution Overview
Problem
Conventional electrical interconnects in multi-chip microelectronic assemblies face issues such as damage, misregistration, and the use of toxic lead solder, which are costly and lack reworkability, and require high processing temperatures, while solder-free solutions with single-point contacts can lead to electrical glitches and are difficult to disassemble.
Innovation Solution
A compact latching spring with multiple contact points that can be assembled and disassembled at room temperature, using a cantilever spring design with mating structures that latch onto a contact pad, eliminating the need for solder and adhesives, and allowing for multiple connect-disconnect cycles without temperature-dependent reflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is used for electrical interconnects, then reliable electrical connection is achieved, but toxic lead is used and high processing temperatures are required
Solution Approach 1:
The patent extracts and eliminates the harmful elements (lead and high temperature processing) from the traditional soldering process by replacing them with a mechanical latching spring system that operates at room temperature, thereby maintaining connection reliability without the harmful factors
Solution Approach 2:
The patent replaces the thermal-mechanical soldering process with a purely mechanical latching spring system that uses elastic deformation and mechanical interlocking to achieve reliable electrical connection without heat or toxic materials
2Ease of manufacture
If a cantilever spring with single point contact is used, then solder-free connection is achieved, but electrical glitches occur when contact moves
Solution Approach 1:
The patent segments the single contact point into multiple contact points (at least two) on the spring tip, which distributes the electrical contact load and maintains stable electrical connection even when the spring moves or deflects
Solution Approach 2:
The patent transitions from a single-point contact (zero-dimensional contact area) to a multi-point contact arrangement, effectively increasing the contact dimensionality and providing redundant electrical pathways that prevent glitches during movement
3Force
If conventional bent cantilever springs are used, then spring contact pressure is maintained, but the springs pop off their mating pads without a fastening mechanism
Solution Approach 1:
The patent introduces asymmetric features including a latch protrusion on one side of the spring tip and a corresponding latch recess on the mating pad, creating a mechanically interlocked configuration that prevents the spring from popping off while maintaining contact pressure
Solution Approach 2:
The patent implements a nested latching mechanism where the latch protrusion fits into the latch recess, creating a interlocking structure that secures the spring to the mating pad and prevents detachment while allowing for controlled assembly and disassembly
4Reliability
If solder or adhesive is used to join parts, then permanent connection is achieved, but reworkability is lost
Solution Approach 1:
The patent creates a dynamic, reversible mechanical connection through the latching spring system that can be easily assembled and disassembled multiple times without degradation, replacing the static permanent bonds of solder or adhesive with a controllable mechanical latch that maintains reliability while enabling reworkability
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 provides reliable, solder-free electrical connections with multiple contact points, enabling easy assembly and disassembly, reducing manufacturing costs, and eliminating the need for high-temperature processing, while maintaining contact integrity through repeated cycles.
Implementation Method 1
a cantilever spring, for example, with a fastening mechanism, is used to hold the interconnect together and maintain spring contact pressure
Data Source
AI summary
An electrical interconnect device attaches electrical devices with a cantilever spring with out the use of solder or adhesive. The cantilever spring latches to a contact structure such that there are a plurality of contact points between the spring and the contact structure. The cantilever spring has two tines at a tip end that define an opening in the spring. The contact structure is received by the opening between the two tines so that the spring and the contact structure mate. The spring may engage the contact structure by latching to the contact structure or by a post that urges the tip end of the spring against the contact structure.