Plastic MID Circuit Assembly Using SMT on Laser-Plated Substrates
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Solution Overview
Problem
Conventional printed circuit board assemblies (PCBAs) are inflexible and require significant space, making it challenging to integrate electronics into miniature, uniquely shaped devices, which increases costs due to space constraints.
Innovation Solution
A method for forming electronic circuits on two-shot injection molded plastic substrates using surface mount technology (SMT) and laser selective plating (LSP), allowing for the creation of multi-dimensional molded interconnect devices (MIDs) with integrated circuitry and components attached using conductive adhesives at lower temperatures, reducing space requirements and improving flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional soldering techniques are used to assemble PCBA, then reliable electrical connections are achieved, but high processing temperatures (180-250°C) and significant space requirements result
Solution Approach 1:
The patent replaces the thermal soldering process with a mechanical bonding process using conductive adhesives. The conductive adhesive forms mechanical bonds between components and substrate while providing electrical connectivity, eliminating the need for high-temperature soldering. This substitution of thermal-metallurgical bonding with mechanical-adhesive bonding resolves the contradiction between connection reliability and processing temperature.
2Reliability
If rigid PCBA substrates are used for electronic assembly, then stable electrical connections are achieved, but flexibility and space efficiency are reduced
Solution Approach 1:
The patent changes the substrate material parameter from rigid PCB to flexible plastic substrate, and changes the bonding method parameter from soldering to conductive adhesive. This dual parameter change enables the substrate to provide both mechanical stability for reliable connections and flexibility for space-efficient integration into miniature devices, resolving the contradiction between connection stability and substrate flexibility.
3Ease of manufacture
If traditional PCBA assembly methods are used, then proven manufacturing processes are employed, but space requirements increase and integration into miniature devices becomes difficult
Solution Approach 1:
The patent merges the substrate structure with the circuit board function, eliminating the need for separate rigid PCB and housing components. By integrating the circuit traces directly into the flexible plastic substrate and using conductive adhesive for component mounting, the design consolidates multiple functions into a single compact assembly, reducing overall volume while maintaining manufacturability.
4Strength
If conventional soldering processes are used, then strong metallurgical bonds are formed, but processing complexity and cost increase for miniature devices
Solution Approach 1:
The patent replaces complex thermal-soldering processes with simpler mechanical-adhesive bonding. The conductive adhesive provides both mechanical bonding and electrical connectivity in a single step, eliminating multiple process steps required for soldering (solder paste application, reflow soldering, inspection). This substitution reduces processing complexity while maintaining bond strength, making it suitable for miniature device manufacturing.
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
Enables the miniaturization and integration of electronic components into complex shapes, reducing space requirements, lowering processing temperatures, and enhancing flexibility and design options for electronic devices.
Implementation Method 1
utilizing a laser selective plating (LSP) process to form conductive traces and/or interconnects
Implementation Method 2
the at least a portion of the plastic substrate surface is prepared to be electrolessly plated with metal
Implementation Method 3
components can be attached using conductive adhesives at lower temperatures
Data Source
Figure 1
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Figure 3~4
AI summary
An apparatus, system and method for forming a molded plastic substrate product for an electronic circuit for a device, wherein the substrate may include one or more electrically conductive traces that are plated and formed on a laser-etched, activated portion of the molded plastic substrate defining each electrically conductive trace. One or more electrically conductive pads may be placed at one or more predetermined positions at the one or more electrically conductive traces. An electrical component surface may then be mounted to the at least one electrically conductive pad using conductive bonding material.