Surface-Mounting Components on Flexible Circuits Using Conductive Adhesives
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Solution Overview
Problem
The production of flexible electronic devices is hindered by the incompatibility of traditional soldering techniques with flexible substrates and the limitations of pick and place machines, leading to high costs and low throughput in manufacturing.
Innovation Solution
A method involving pre-configured arrays of surface-mounted electronic components attached with anisotropic conductive adhesives, allowing for rapid transfer to flexible printed circuits using low temperature and pressure, eliminating the need for high-temperature soldering and pick and place machines, and enabling roll-to-roll production of uniform light sources on flexible substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional soldering techniques are used to join surface mount components, then strong electrical connections are achieved, but the process is incompatible with flexible substrates due to high temperatures and rigidity
Solution Approach 1:
The patent changes the temperature parameter from high-temperature soldering (>200°C) to low-temperature curing (<150°C or room temperature with UV light), and changes the material state from rigid metallic solder to flexible polymer-based conductive adhesive, enabling compatibility with flexible substrates while maintaining electrical connection strength
Solution Approach 2:
The patent replaces the mechanical soldering process with a chemical bonding process using conductive adhesives that cure through chemical reactions (heat or UV-induced polymerization), eliminating the need for high-temperature thermal-mechanical soldering operations
2Manufacturing precision
If pick and place machines are used to place components, then precise component placement is achieved, but the production cost increases and throughput decreases
Solution Approach 1:
The patent pre-arranges components in their final positions on the flexible substrate before the substrate is cured, eliminating the need for subsequent pick-and-place operations. This preliminary positioning is achieved through the flexibility of the substrate during assembly, allowing components to be placed and held in position before permanent fixation
Solution Approach 2:
The patent utilizes the dynamic flexibility of the uncured substrate to enable easy component placement and repositioning, then transitions to a rigid fixed state after curing, thereby achieving both ease of assembly and permanent secure mounting without requiring complex automated placement machinery
3Adaptability or versatility
If conductive adhesives are used instead of solder paste, then compatibility with flexible substrates is improved, but the electrical conductivity decreases
Solution Approach 1:
The patent employs composite conductive adhesives containing conductive fillers (such as metal particles, flakes, or fibers) dispersed in a polymer matrix, combining the flexibility and adhesion benefits of polymers with the electrical conductivity of metallic particles, thereby achieving both substrate compatibility and adequate electrical performance
Solution Approach 2:
The patent optimizes the local concentration, size, shape, and distribution of conductive fillers within the adhesive to achieve sufficient electrical conductivity at the component-substrate interface while maintaining the overall flexibility and processability of the adhesive material
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 method enables fast, economical, and high-throughput production of flexible electronic devices with uniform light output, overcoming the limitations of traditional techniques by using anisotropic conductive adhesives for component attachment and a flexible polymer diffuser for uniform light distribution.
Implementation Method 1
anisotropic conductive adhesives (ACAs) which conduct only in the z-axis when compressed between electrodes
Implementation Method 2
polymer binders packed with conductive materials (conductive binders) largely cure at temperatures lower than 150° C., or at room temperature by application of ultraviolet light
Implementation Method 3
a flexible polymer diffuser for uniform light distribution
Data Source
AI summary
A method of connecting a plurality of electronic components to a flexible circuit board comprises: providing a carrier substrate carrying the electronic components, each of the electronic components having at least one electrical contact coated with electrically conductive adhesive; and applying the carrier substrate to the flexible circuit board such that the electronic components are adhered to the flexible circuit board in electrical contact therewith via the conductive adhesive. The electronic components may comprise LEDs and there may be provided one or more optical layers over the flexible circuit board.