Bonded Body with Infiltrating Elastomer Layer for Metal-Resin Joints
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Solution Overview
Problem
Existing methods for bonding metal to resin using laser welding result in insufficient bonding strength due to voids in the metal surface and limited shape flexibility, leading to low quality stability and high waste generation.
Innovation Solution
A bonding method involving an injection-molded bonding layer with a tensile elastic modulus of 1200-2000 MPa, containing 5-75 wt% elastomer, which infiltrates into metal surface pores, enhancing bonding strength and allowing for three-dimensional shape compatibility without the need for custom laser bonding sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If laser welding is used to bond metal and resin, then bonding speed is improved, but bonding strength deteriorates due to voids remaining in metal surface gaps
Solution Approach 1:
The bonding layer is applied to the metal surface before the final bonding process. This preliminary action allows the bonding layer to infiltrate and fill the gaps and pores on the metal surface in advance, preventing void formation during subsequent bonding operations and ensuring complete coverage without compromising bonding speed
Solution Approach 2:
A bonding layer serves as an intermediary material between the metal and resin components. This bonding layer with specific elastic modulus (1200-2000 MPa) acts as a mediator that fills surface irregularities, accommodates thermal expansion differences, and creates a reliable bonding interface that eliminates voids while maintaining efficient bonding processes
2Ease of manufacture
If a flat laser bonding sheet is used, then manufacturing simplicity is improved, but adaptability to three-dimensional shapes deteriorates
Solution Approach 1:
The bonding layer's physical parameters, particularly its elastic modulus (1200-2000 MPa), are optimized to enable it to conform to three-dimensional surfaces while maintaining structural integrity. This parameter optimization allows the bonding layer to adapt to complex geometries without requiring custom manufacturing for each shape, balancing manufacturing simplicity with shape versatility
Solution Approach 2:
The bonding layer is designed as a composite material system with specific mechanical properties (tensile elastic modulus of 1200-2000 MPa) that combines the benefits of flexibility for shape adaptation with sufficient strength for reliable bonding, eliminating the need for shape-specific custom bonding sheets
3Device complexity
If laser bonding sheet is simply interposed between members, then process complexity is reduced, but position holding properties deteriorate leading to quality instability
Solution Approach 1:
The bonding layer is positioned and secured to the metal surface through preliminary actions such as adhesion or mechanical interlocking before the final assembly. This preliminary positioning ensures stable location retention throughout the bonding process and subsequent handling, eliminating quality instability without adding complex positioning mechanisms
Solution Approach 2:
The bonding layer acts as an intermediary that provides inherent position holding through its adhesive properties and mechanical interlocking with the metal surface. This intermediary function stabilizes the assembly during processing and ensures consistent bonding quality without requiring additional complex positioning devices or procedures
4Manufacturing precision
If custom laser bonding sheets are manufactured to match bonding surfaces, then bonding precision is improved, but waste generation and processing costs increase
Solution Approach 1:
The bonding layer's mechanical parameters, specifically its tensile elastic modulus range of 1200-2000 MPa, are optimized to enable it to conform to various bonding surfaces while maintaining adequate bonding precision. This parameter optimization allows a standardized bonding layer to achieve precise bonding results without requiring custom manufacturing for each application, thereby reducing waste and processing costs
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 method significantly enhances bonding strength, reduces voids, and stabilizes bonding quality while minimizing waste and processing costs, allowing for effective bonding of metal and resin with three-dimensional shapes.
Implementation Method 1
the material of the laser bonding sheet does not infiltrate into gaps such as pores formed on the surface of the first member formed of metal
Implementation Method 2
melting the laser bonding sheet through laser light irradiation
Implementation Method 3
melting the laser bonding sheet through laser light irradiation
Implementation Method 4
the linear expansion relaxation effect of the bonding layer is decreased
Data Source
Figure 1
Figure 2(a)~2(d)
Figure 3(a)~3(b)
AI summary
In a bonded body (1), a first member (2), and a second member (3) formed of a material different from that of the first member (2) are bonded to each other via a bonding layer (4) interposed therebetween. In a range of 13 µm in a cross-section of a bonding interface between the first member (2) and the bonding layer (4), the number of air bubbles having a void area of 1.5×10-3 µm2 or greater is 100 or less.