Reactive Hot-Melt Adhesive Lamination for Multilayer Bus Bars
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Solution Overview
Problem
Current methods for assembling high-power multilayer bus bars are time-consuming, energy-intensive, and labor-intensive, with difficulties in controlling adhesive thickness and requiring additional hardware, which limits their efficiency and performance in high-power applications.
Innovation Solution
The use of a reactive hot-melt adhesive to bond conductive subassemblies to a dielectric layer, allowing for rapid lamination at lower temperatures and pressures, resulting in improved bonding strength and reduced assembly time, while maintaining high cleavage strength and environmental resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermoplastic film adhesives are used to assemble bus bars, then bonding between subassemblies is achieved, but assembly time increases to 30-45 minutes and energy consumption increases due to heating requirements
Solution Approach 1:
The patent changes the adhesive from thermoplastic to reactive hot-melt adhesive, which undergoes chemical crosslinking at lower temperatures (60-100°C) compared to thermoplastic adhesives requiring higher temperatures and longer times. This parameter change in adhesive chemistry enables faster curing while maintaining bonding strength.
Solution Approach 2:
The patent replaces the thermal-mechanical bonding process of thermoplastic adhesives with a chemical bonding process using reactive hot-melt adhesives that cure through crosslinking reactions. This substitution eliminates the need for prolonged heating and pressure application, reducing assembly time significantly.
2Strength
If thermoset B-staged bondply is used to assemble bus bars, then bonding between subassemblies is achieved, but assembly time increases to 1-2 hours and energy consumption increases due to curing requirements
Solution Approach 1:
The patent changes from thermoset bondply requiring extended curing (1-2 hours) to reactive hot-melt adhesive that cures rapidly at lower temperatures through crosslinking. This chemical parameter change reduces the curing time and energy input required while achieving equivalent or superior bonding strength.
Solution Approach 2:
The reactive hot-melt adhesive is applied in a pre-heated molten state that facilitates immediate wetting and initial bonding upon contact with substrates. This preliminary action of pre-heating the adhesive before application enables faster overall curing compared to cold-application thermoset systems that require extended curing from ambient temperature.
3Strength
If two component liquid epoxy adhesive is used to assemble bus bars, then bonding between subassemblies is achieved, but adhesive thickness control becomes difficult and labor requirements increase
Solution Approach 1:
The patent changes from two-component liquid epoxy requiring manual mixing and application to hot-melt adhesive applied in a controlled molten state. The temperature-controlled application process enables precise thickness control through parameters like application temperature, pressure, and speed, eliminating the thickness variability inherent in manual liquid adhesive application.
Solution Approach 2:
The patent replaces manual brushing or spreading of liquid epoxy with a controlled hot-melt adhesive application system. The molten adhesive can be applied using rollers, extruders, or spray systems that provide consistent thickness control, replacing the manual labor-intensive process with a more controllable mechanism.
4Strength
If mechanical fasteners are used to secure bus bar subassemblies, then structural integrity is achieved, but additional hardware requirements and labor requirements increase
Solution Approach 1:
The patent merges the bonding function with the adhesive layer itself, eliminating the need for separate mechanical fasteners. The reactive hot-melt adhesive provides both bonding and structural integrity functions that would otherwise require additional hardware, simplifying the overall assembly.
Solution Approach 2:
The patent extracts and removes mechanical fasteners (nuts, bolts, rivets) from the assembly process, relying solely on the chemical bonding capability of the reactive hot-melt adhesive to provide structural integrity. This extraction eliminates hardware requirements and associated labor.
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
The reactive hot-melt adhesive method significantly reduces assembly time, enhances bonding strength, and improves electrical performance, drop test performance, and thermal aging of the bus bars, making them suitable for high-power applications with lower production costs.
Implementation Method 1
a reactive hot-melt adhesive adapted to bond the first and second subassemblies to the dielectric layer
Implementation Method 2
coating a dielectric layer with a molten reactive hot-melt adhesive
Data Source
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AI summary
A method of assembling a multilayer bus bar assembly includes coating a dielectric layer with a molten reactive hot-melt adhesive, placing the dielectric layer between first and second subassemblies, wherein the first and second subassemblies comprise a conductive element, adhering the molten reactive hot-melt adhesive to the subassemblies by applying a pressure of at least about one bar to the multilayer bus bar assembly for at least about one minute prior to the adhesive cooling to room temperature to provide a bonding strength between the dielectric material and a selected one of the first and second subassemblies of at least 1500 Newtons on a 25 millimeter by 25 millimeter sample when tested in accordance with ASTM D- 1062.