Overmoulded Printed Electronics Using Sintered Molecular Inks
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Solution Overview
Problem
Current methods for manufacturing overmoulded printed electronic parts face challenges such as limited formability, high resistivity, and visual defects due to the use of metal flake inks, leading to heavy and thermally poor performing parts, primarily suited for non-structural interior applications.
Innovation Solution
A method involving the deposition of molecular ink on a substrate, followed by sintering to form a conductive silver trace, and subsequent injection and hardening of an overmoulding resin, which can include using low temperature molecular inks, nanoparticle inks, thermoset resins, glass microspheres, or foamed resins to enhance conductivity and reduce part thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal flake inks are used in printed electronics, then conductivity can be achieved, but the parts have high resistivity and limited formability
Solution Approach 1:
The patent changes the material parameters by transitioning from metal flake inks to molecular inks that sinter into conductive silver traces. This parameter change enables both adequate conductivity and superior formability, as the sintered silver traces can be deformed without breaking unlike rigid metal flakes.
Solution Approach 2:
The patent employs a disposable substrate film approach where the substrate with printed conductive traces is discarded after transfer to the overmoulded part. This eliminates the need for durable, reusable substrate materials and allows use of thinner, more formable films that serve their purpose during manufacturing.
2Ease of manufacture
If standard types of molten resin are injected into the cavity, then overmoulding can be achieved, but visual defects such as ghosting or circuit printing appear
Solution Approach 1:
The patent changes the resin parameters by using specially formulated overmoulding resins with optimized viscosity and curing characteristics. These resins flow better to avoid trapping air bubbles and cure more uniformly to prevent ghosting and circuit printing defects while maintaining ease of injection moulding.
3Strength
If ribs and increased part thickness are used to increase rigidity, then structural strength is improved, but the parts become heavy and use significant quantities of thermoplastic resin
Solution Approach 1:
The patent uses composite construction by overmoulding a thin printed electronic substrate with a structural thermoplastic resin. This composite structure provides the necessary rigidity and strength through the overmoulded resin while keeping the overall part thickness and weight minimal, as the substrate itself remains thin.
Solution Approach 2:
The patent segments the part into two functional zones: a thin substrate layer containing the printed electronic traces and a separate overmoulded structural layer providing rigidity. This segmentation allows each layer to be optimized independently - the substrate for electrical functionality and the overmoulded resin for mechanical strength.
4Ease of operation
If the final thickness is increased to create space for LEDs and connectors, then component stand-off is achieved, but thermal performance deteriorates
Solution Approach 1:
The patent applies local quality by creating localized stand-off features only where LEDs and connectors are positioned, rather than uniformly increasing the entire part thickness. This allows adequate space for components in specific areas while maintaining thin overall dimensions to preserve thermal performance.
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 production of lighter, more rigid, and thermally improved overmoulded printed electronic parts suitable for structural applications by minimizing material thickness and optimizing electrical performance.
Implementation Method 1
sintering the non-conductive trace of the ink on the substrate to form a conductive silver trace on the first surface of the substrate
Implementation Method 2
hardening the overmoulding resin or curing the precursor thereto to obtain the overmoulded printed electronic part
Data Source
AI summary
The present application relates to overmoulded printed electronic parts as well as to methods for preparing overmoulded printed electronic parts using conductive trace inks such as molecular inks, thermoset resins, and reinforcing materials such as glass microspheres and glass fabric.