Glazing Panel Antenna Connector Using Lead-Free Solder
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Solution Overview
Problem
Existing lead-based solder materials used in connecting electrically functional components to glazing panels in vehicles cause mechanical stress due to thermal expansion differences, leading to potential damage and are environmentally hazardous, while lead-free alternatives often result in poor solderability and cohesive strength.
Innovation Solution
A flat electrically conductive connector with laminated resilient material and a lead-free solder material, such as SAC305, is used to connect antennas to coaxial cables, minimizing thermal expansion differences and ensuring strong bonding and fatigue resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-based solder material is used to connect the connector to the antenna, then the mechanical stress between the connector and the substrate is minimized due to deformability of lead, but the environmental hazard increases and the use is prohibited by EU legislation
Solution Approach 1:
The invention changes the material parameters of the solder material by incorporating specific amounts of indium (0.1-10 wt%) and bismuth (0.1-10 wt%) along with tin and silver. This parameter change allows the lead-free solder to achieve both low melting point (for stress absorption) and good solderability (radical reaction control), while meeting environmental requirements by eliminating lead.
Solution Approach 2:
The invention uses a composite solder material system comprising multiple elements (Sn, Ag, In, Bi) working together. The multi-element composition creates a synergistic effect where indium provides low melting point and ductility, bismuth suppresses radical reactions, tin provides base solderability, and silver enhances electrical conductivity and strength, collectively replacing lead's functions without its environmental harm.
2Object-affected harmful factors
If conventional lead-free solder materials (high tin with silver, copper, indium, and bismuth) are used to replace lead, then the environmental hazard is reduced, but the radical reaction rate between tin and silver increases resulting in poor solderability
Solution Approach 1:
The invention optimizes the compositional parameters by limiting indium to 0.1-10 wt% and bismuth to 0.1-10 wt%, with silver at 0.1-5 wt%. This precise parameter control balances the competing effects: enough indium for low melting point but not so much as to cause excessive softness, and controlled bismuth to suppress radical reactions between tin and silver, thereby achieving both environmental compliance and good solderability.
3Object-affected harmful factors
If conventional lead-free solder materials are used, then the environmental hazard is reduced, but the mechanical stress between the connector and the substrate is not absorbed resulting in cracking or damage to the substrate
Solution Approach 1:
The invention changes the thermal and mechanical parameters of the solder material by incorporating indium (0.1-10 wt%) which has a very low melting point (157°C) and high ductility, and bismuth (0.1-10 wt%) which provides thermal expansion compatibility. This parameter modification enables the solder joint to absorb thermal expansion differences between the copper connector and glass substrate during temperature cycling, preventing substrate cracking while maintaining environmental compliance.
4Object-affected harmful factors
If alternative materials for the connector are used to replace lead-based connectors, then the environmental hazard is reduced, but the solderability and adhesion to the electrically functional component deteriorates
Solution Approach 1:
The invention employs a composite solder material system with controlled composition ratios where tin (60-95 wt%) provides base adhesion, silver (0.1-5 wt%) enhances electrical conductivity and bond strength, indium (0.1-10 wt%) improves ductility and wetting, and bismuth (0.1-10 wt%) suppresses harmful radical reactions. This composite approach achieves strong adhesion to alternative connector materials while meeting environmental requirements.
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 solution provides a reliable and environmentally friendly connection for high-frequency antennas, maintaining signal integrity and preventing damage to the glazing panel while adhering to EU regulations by reducing mechanical stress and improving solderability.
Implementation Method 1
differences in coefficients of thermal expansion between the connectors, which are typically made of a good conductive material such as copper, and the substrates cause the mechanical stress
Implementation Method 2
an electrically conductive connector provided with solder material is placed on the contact surface of the glazing panel and is then heated so that the solder material melts with the contact surface of the glazing panel
Data Source
AI summary
A glazing panel comprising (i) a pane of glass, (ii) an antenna, (iii) an electrically conductive connector joined to the antenna by a solder material, and (iv) a coaxial cable joined to the electrically conductive connector. The electrically conductive connector is a flat connector comprising first and a second electrically conductive portions laminated between two films of a resilient material.