Flexible Circuit Assembly with Embedded Power Devices
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Solution Overview
Problem
Existing flexible printed circuit technologies are inefficient in accommodating multiple power devices due to rigidity, heat management issues, and complex, costly manufacturing processes, which hinder their use in compact, high-power applications.
Innovation Solution
A flexible circuit assembly design featuring an insulating cover layer, a flexible conductive layer with islands and conductive traces, and heat-conductive elements, allowing for efficient heat dissipation and bending without cracking, integrated with a roll-to-roll manufacturing process for cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If surface mounted devices (SMDs) are mounted onto the surfaces of the flexible circuit, then electrical or electronic devices can be integrated, but the flexible circuit assembly becomes more rigid and less flexible, and the height substantially increases
Solution Approach 1:
The patent embeds power devices inside openings formed in the flexible circuit layers, nesting them within the circuit structure rather than mounting them on the surface. This allows device integration while maintaining the flexibility of the overall assembly, as the devices are contained within the flexible layers rather than adding external height and rigidity
Solution Approach 2:
The patent uses a flexible circuit assembly with thin flexible layers that can be bent and rolled. By embedding devices within these flexible layers rather than surface mounting, the assembly maintains its flexibility and can achieve bending radii of 3cm or less without cracking, while still accommodating multiple power devices
2Adaptability or versatility
If more layers of metal and non-conductive substrates are added to the sandwich, then the circuit can accommodate more devices, but the flexible printed circuit becomes less flexible
Solution Approach 1:
The patent forms openings through multiple flexible layers and embeds power devices within these openings, allowing multiple devices to be accommodated across different layers while maintaining the flexibility of each layer. The devices are nested within the flexible structure rather than requiring additional rigid support layers
Solution Approach 2:
The patent uses composite flexible circuit structures with multiple flexible layers (including polyimide and other flexible materials) that can be bent and rolled. The combination of flexible layers with embedded devices creates a composite structure that maintains flexibility while accommodating multiple power devices, achieving bending radii of 3cm or less
3Ease of manufacture
If conventional FR4 and adhesive materials are used for PCBs, then manufacturing is straightforward, but they cannot be processed above 270° C. and higher melting, lead-free solders require bonding at higher temperatures that can decompose the materials
Solution Approach 1:
The patent changes the material parameters by using flexible circuit materials with higher temperature resistance (such as polyimide and other high-temperature flexible materials) instead of conventional FR4. This allows the assembly to withstand processing temperatures above 270° C. and enables the use of lead-free solders without decomposing the substrate materials
Solution Approach 2:
The patent uses composite flexible circuit materials that combine high temperature resistance with flexibility. These composite materials can withstand the higher processing temperatures required for lead-free soldering while maintaining the flexibility and workability needed for manufacturing, eliminating the decomposition issue associated with conventional FR4 at elevated temperatures
4Temperature
If bulky metallic copper or aluminum fins heat sinks are attached to transfer heat away from mounted devices, then heat dissipation is improved, but the assembly becomes bulky, heavy, and very inflexible
Solution Approach 1:
The patent replaces bulky metallic heat sinks with thin flexible heat sink layers that can be integrated into the flexible circuit assembly. These thin film heat sink structures maintain heat dissipation functionality while preserving the flexibility and reducing the weight and bulk of the assembly, enabling bending radii of 3cm or less
Solution Approach 2:
The patent embeds heat-conductive elements and thin flexible heat sink layers within the flexible circuit structure, nesting them inside the flexible layers rather than attaching bulky external heat sinks. This integrated approach maintains heat dissipation efficiency while preserving the flexibility and reducing the overall size and weight of the assembly
5Object-affected harmful factors
If additional metal casings are used for electro-magnetic shielding, then EMI protection is improved, but cost, weight, and inflexibility increase, and thermal energy extraction is decreased
Solution Approach 1:
The patent integrates multiple functions into the flexible circuit layers themselves, which provide both structural support and electromagnetic shielding capabilities. The flexible layers with embedded devices and heat-conductive elements serve multiple purposes, eliminating the need for separate metal casings for EMI protection while maintaining shielding effectiveness and preserving flexibility
Solution Approach 2:
The patent merges the electromagnetic shielding function with the structural and thermal management functions of the flexible circuit assembly. By integrating these functions into the flexible layers rather than adding separate metal casings, the assembly achieves EMI protection without increased weight, while maintaining flexibility and improving thermal energy extraction through the embedded heat-conductive elements
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 flexible integration of multiple power devices with enhanced heat management and reduced size and weight, facilitating efficient power dissipation and cost-effective automated manufacturing.
Implementation Method 1
heat-conductive elements arranged inside the second openings, a first thin heat sink layer, the heat-conductive elements arranged to be in contact with an upper surface of the thin heat sink layer and the lower surface of the islands via heat-conductive material
Data Source
AI summary
A flexible circuit assembly for accommodating a plurality of power electronic devices, including an insulating cover layer having first openings for power electronic devices, a flexible conductive layer arranged under the insulating cover layer and attached with a first adhesive to the insulating cover layer, an intermediate insulating layer arranged under the flexible conductive layer and attached with a second adhesive to the flexible conductive layer, the intermediate insulating layer having second openings, a plurality of heat-conductive elements arranged inside the second openings, a first thin heat sink layer, the heat-conductive elements arranged to be in contact with an upper surface of the thin heat sink layer and the lower surface of the islands via heat-conductive material; and a second thin heat sink layer, upper surfaces of the power electronic devices arranged to be in contact with a lower surface of the thin heat sink layer and the lower surface of the islands via heat-conductive material.