Wire Bonded Electronic Devices to Round Wire on Flexible Substrates
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Solution Overview
Problem
Existing methods for mounting electronic devices on flexible substrates, such as RF transponders and LEDs, are costly due to print-and-etch processes that require expensive chemicals and generate hazardous waste, and often result in higher profiles due to the use of lead frames.
Innovation Solution
A circuit arrangement using a flexible substrate with pressure-sensitive adhesive (PSA) and round cross-section metal foil pads, where electrically conductive wire with weld joints is attached directly to the pads, eliminating the need for lead frames and reducing costs by using wire bonding techniques that avoid hazardous chemicals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If print-and-etch processes are used to create wiring patterns on flexible substrates, then electronic devices can be mounted on flexible substrates, but the manufacturing cost increases due to expensive chemicals and hazardous waste
Solution Approach 1:
The patent extracts and eliminates the print-and-etch process entirely from the manufacturing workflow. Instead of using chemical-based wiring patterns, the invention uses pre-formed conductive traces that are mechanically attached to the flexible substrate, thereby removing the source of hazardous waste and reducing manufacturing costs associated with chemical processing
Solution Approach 2:
The patent employs disposable conductive traces that can be easily attached and removed without requiring expensive chemical processing. These traces are designed for single-use applications where the cost of the trace itself is lower than the cost of the chemical processes traditionally required to create conductive pathways
2Device complexity
If lead frames are used as carriers for electronic devices, then electronic devices can be mounted and connected, but the profile height increases which may not be desired
Solution Approach 1:
The patent extracts and removes the lead frame component from the mounting structure. By eliminating the rigid lead frame carrier, the invention achieves a lower profile while maintaining the necessary electrical connections through alternative mounting methods that directly attach electronic devices to the flexible substrate
Solution Approach 2:
The patent uses flexible conductive traces and thin-film mounting structures instead of rigid lead frames. These flexible components provide the necessary electrical connectivity and mechanical support while maintaining a low profile that conforms to the flexible substrate, eliminating the height penalty associated with traditional lead frames
3Ease of manufacture
If wire bonding techniques are used to connect electronic devices to round wire, then the structure becomes low-cost and low-profile, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-forming the conductive traces and preparing the mounting surfaces before the wire bonding step. The round wire is pre-positioned and secured to the flexible substrate, and electronic devices are pre-aligned, which simplifies the subsequent wire bonding process and reduces overall manufacturing complexity despite adding a wire bonding step
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 low-cost, low-profile, flexible, and durable structures that can withstand hundreds of thousands of flexes, suitable for applications like wearable devices, with reduced environmental impact and improved durability compared to traditional methods.
Implementation Method 1
A first layer of pressure sensitive adhesive (PSA) has third and fourth major surfaces. The third major surface is opposite the fourth major surface, and the fourth major surface is directly adhered to the first major surface of the substrate.
Implementation Method 2
The wire has a round cross-section and one or more portions directly connected to the one or more metal foil pads with one or more weld joints, respectively.
Implementation Method 3
The electronic device is attached directly on the third major surface of the first layer of PSA and is electrically connected to the one or more portions of the round wire by one or more bond wires, respectively.
Data Source
AI summary
A disclosed circuit arrangement includes a flexible substrate. A layer of pressure sensitive adhesive (PSA) is directly adhered to a first major surface of the substrate. One or more metal foil pads and electrically conductive wire are attached directly on a surface of the PSA layer. The wire has a round cross-section and one or more portions directly connected to the one or more metal foil pads with one or more weld joints, respectively. An electronic device is attached directly on the surface of the layer of PSA and is electrically connected to the one or more portions of the round wire by one or more bond wires, respectively.