Solder-Free Rigid-Flex Circuit Assembly with Conductive Substrates
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Solution Overview
Problem
The electronics industry faces challenges in manufacturing rigid flex circuit assemblies due to the limitations of traditional soldering methods, including high temperatures required for lead-free solders, susceptibility to mechanical failure, and environmental impact, which complicates the assembly process and reduces reliability.
Innovation Solution
The development of a method for manufacturing rigid-flex circuit assemblies using thermally and electrically conductive substrates with electronic components interconnected via flexible sections without solder, utilizing plated interconnections and low-temperature processes to reduce weight, improve thermal dissipation, and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-free solder is used for interconnection, then reliability is improved by eliminating lead, but manufacturing temperature must be increased which causes thermal damage to components
Solution Approach 1:
The patent extracts and eliminates the solder material entirely from the interconnection process. Instead of using lead-free solder requiring high temperatures, the invention uses direct mechanical interlocking structures and conductive adhesives that operate at low temperatures, thereby removing the source of thermal damage while maintaining reliable electrical connections.
Solution Approach 2:
The patent replaces the thermal-mechanical soldering process with a purely mechanical interlocking system. The circuit board features integrated mounting structures such as recesses, protrusions, and snap-fit mechanisms that mechanically secure components without requiring high-temperature bonding, thus substituting thermal processing with mechanical assembly.
2Reliability
If traditional soldering process is used, then electrical interconnection is achieved, but assembly complexity increases due to multiple processing steps
Solution Approach 1:
The patent merges the electrical interconnection function with the mechanical mounting function into a single integrated structure. The circuit board incorporates conductive traces, mounting features, and connection interfaces in one unified design, allowing components to be mechanically attached and electrically connected simultaneously, thereby eliminating separate soldering steps and reducing assembly complexity.
Solution Approach 2:
The patent creates multi-functional circuit board structures that simultaneously provide mechanical support, electrical connection, and thermal management. The integrated design serves multiple purposes with single structures, reducing the number of separate components and assembly steps required, thereby simplifying the overall manufacturing process.
3Strength
If high-temperature soldering is used, then strong electrical bonds are formed, but thermal damage to electronic components increases
Solution Approach 1:
The patent prepares the circuit board with pre-formed mechanical interlocking structures and conductive pathways before component assembly. The mounting features and electrical traces are integrated into the board structure in advance, allowing components to be attached at low temperatures using mechanical insertion or low-temperature adhesives, thereby preventing thermal damage while ensuring strong joints through proper mechanical design.
4Productivity
If solder alloy is used for mass joining, then manufacturing efficiency is improved, but susceptibility to mechanical failure increases
Solution Approach 1:
The patent employs conductive adhesives as a low-cost, disposable bonding material that replaces durable but fragile solder joints. These adhesives provide sufficient electrical conductivity and mechanical bonding for the application, and while they may have lower long-term durability than solder, they eliminate the tin whisker problem and provide adequate performance at a fraction of the cost and complexity.
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 results in lighter, more reliable, and cost-effective assemblies with reduced processing steps, eliminating the need for high-temperature soldering and minimizing exposure to heat-related damages, thereby improving the manufacturing efficiency and performance of rigid flex circuit assemblies.
Implementation Method 1
thermally and electrically conductive substrates with electronic components interconnected via flexible sections without solder, utilizing plated interconnections
Implementation Method 2
thermally and electrically conductive substrates with electronic components interconnected
Data Source
AI summary
A rigid flex circuit comprised of high thermal conductivity sections, said sections having components disposed so as to have their contacts substantially planar with the surface of the thermally conductive section and wherein the contacts are interconnected directly to the traces without the use of solder and further having the thermally conductive sections interconnected to one another by means of flexible circuit sections.