Monolithic Molded Flexible Electronic Assemblies Without Solder

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Solution Overview

Problem

The electronics industry faces challenges with the assembly of flexible circuits using solder, particularly with lead-free solders, which require high temperatures, are environmentally damaging, and result in less reliable electronic assemblies due to added weight and cost concerns with adhesive and socket solutions.

Innovation Solution

A method involving a mold with two portions that form an interior chamber, where electronic parts with contacts are embedded in a hardened insulating molding material, and solderless conductive circuits are applied to create a monolithic molded electronic assembly, allowing for flexible and robust circuit assemblies without the need for solder.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If lead-free solder is used for assembly, then environmental compliance is improved, but reliability deteriorates due to higher temperatures required

Engineering Contradiction:

Improveenvironmental complianceVSAvoidassembly reliability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent extracts the joining function from traditional soldering processes by using molded assemblies where components are permanently attached during molding, eliminating the need for separate soldering steps and avoiding lead-free solder reliability issues

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the component attachment and circuit board formation processes into a single molding operation, where components are attached and encapsulated simultaneously, eliminating temperature cycles associated with soldering

Inventive Principle:

Principle #5Merging (Combining)

2Ease of operation

If adhesive solutions are used instead of solder, then ease of operation is improved for component removal, but conductivity deteriorates

Engineering Contradiction:

Improvecomponent removalVSAvoidelectrical conductivity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces mechanical/adhesive bonding with permanent molded attachment, where the molding material itself forms the structural and electrical connection, eliminating the need for adhesives while maintaining conductivity through direct metal-to-metal contact in the molded assembly

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If socket solutions are used for separable connections, then adaptability is improved for replacement, but weight increases due to constant applied force requirements

Engineering Contradiction:

Improvecomponent replacementVSAvoidassembly weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent creates permanently attached molded assemblies where the rigid molded structure provides mechanical support and electrical connection simultaneously, eliminating the need for resilient contact structures and constant applied force required by sockets

Inventive Principle:

Principle #15Dynamics

4Manufacturing precision

If traditional soldering processes are used, then manufacturing precision is maintained, but temperature requirements worsen environmental impact

Engineering Contradiction:

Improveconnection precisionVSAvoidenvironmental damage from high temperature

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent performs component attachment and encapsulation in a single preliminary molding action before final circuit board assembly, eliminating subsequent high-temperature soldering operations and their associated environmental impacts

Inventive Principle:

Principle #10Preliminary action

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 enables the creation of reliable, flexible, and cost-effective electronic assemblies with improved reliability and reduced environmental impact by eliminating the need for high-temperature soldering and providing a robust, solderless connection method.

Implementation Method 1

The molding material is hardened from the liquid state to a solid state, thereby embedding the plurality of electronic parts in the molding material as a monolithic sub-assembly

Methodology Applied

Scientific EffectPhase change (liquid to solid): Phase Change

Data Source

PatentUS8093712B2Monolithic molded flexible electronic assemblies without solder and methods for their manufacture

Publication Date: 2012.01.10 FJELSTAD JOSEPH CHARLES

AI summary

A method (10) for manufacturing a monolithic molded electronic assembly (12). A mold (14) having first and second mold potions (14a-b) that mate to form an interior chamber (16) is provided. The mold has an injection port (22) and channel (24) connecting into the chamber. Electronic parts (30) having electronic contacts (32) are populated onto the second mold portion, to be substantially contained in the chamber. The mold potions are mated together and a liquid insulating molding material (36) is injected through the injection port channel to fill the chamber. The molding material is hardened to a solid, thereby embedding the electronic parts in the molding material as a monolithic sub-assembly (40). The monolithic sub-assembly is removed from the mold and one or more solderless conductive circuits (50) are applied to the electronic contacts of the electronic parts, thereby providing the electronic assembly.