Precompressed Contact Pad Direct Sintering Assembly
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Solution Overview
Problem
Current methods for assembling large-section electrical contact pads on metal supports are costly and time-consuming, with issues such as high manufacturing costs, lengthy processes, and quality control challenges due to the use of undercoats and silver-based solders, leading to irregularities and decohesions during the assembly of copper-based contacts.
Innovation Solution
A direct cold sintering process is used to assemble a precompressed contact pad with a conductive silver layer, a reactive underlayer containing a pseudo-alloy of silver and copper, and a stripping agent, along with refractory, anti-welding, and gas-generating elements, directly onto a copper metal support, utilizing induction heating and compression forces to form metallurgical bonds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resistance welding methods with solder addition are used to assemble contact pads on metal supports, then the quality of connection and mechanical strength are improved, but the manufacturing cost increases significantly
Solution Approach 1:
The invention extracts and eliminates the solder layer from the traditional multi-layer contact pad structure. By using a copper support with a copper-rich underlayer instead of silver-based solder, the patent removes the expensive material while maintaining assembly quality through direct metallurgical bonding between copper layers.
Solution Approach 2:
The invention changes the material composition parameters of the underlayer, making it copper-rich (≥80% copper) rather than silver-based. This parameter change allows the underlayer to bond metallurgically with the copper support directly, eliminating the need for solder while reducing manufacturing cost.
2Reliability
If traditional multi-step processes including co-rolling, bi-extrusion, or sintering are used to obtain contact pads, then the assembly quality can be maintained, but the overall manufacturing time increases
Solution Approach 1:
The invention merges the underlayer formation with the contact pad manufacturing process itself. The underlayer is created as an integral part of the contact pad during the same sintering or extrusion process, eliminating separate undercoat application steps and reducing overall manufacturing time.
Solution Approach 2:
The invention performs preliminary action by pre-forming the copper-rich underlayer as an integral part of the contact pad during manufacturing. This preliminary formation of the bonding layer eliminates the need for subsequent undercoat application and solder deposition steps.
3Reliability
If manual operations of laying flux and soldering are used during assembly, then the bonding quality can be improved, but the manufacturing time and process complexity increase
Solution Approach 1:
The invention enables self-service by designing the underlayer with self-fluxing properties through its copper-rich composition and controlled oxygen content. The material itself provides the necessary chemical reactivity for bonding without requiring external flux application, eliminating manual fluxing operations.
Solution Approach 2:
The invention replaces the manual mechanical operations of flux application and soldering with a materials-based solution. The copper-rich underlayer's inherent chemical properties enable direct metallurgical bonding through controlled heating, substituting complex manual processes with a simpler thermal treatment.
4Shape
If cutting operations are performed on co-rolled or bi-extruded pellets to obtain final contact pads, then the desired shape and dimensions are achieved, but decohesions occur at the cutting edge due to differential thermal expansion
Solution Approach 1:
The invention applies homogeneity by using a copper-rich underlayer (≥80% copper) that has similar thermal expansion characteristics to the copper support and contact material. This compositional homogeneity reduces differential thermal expansion during annealing, preventing edge decohesion during cutting operations.
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 method reduces manufacturing time and costs while improving the quality and reliability of the electrical contact assembly by ensuring consistent bonding and high mechanical strength, even for large-section contacts, effectively addressing the limitations of existing assembly techniques.
Implementation Method 1
said underlayer having a melting temperature lower than that of the layer of contact
Implementation Method 2
utilizing induction heating and compression forces to form metallurgical bonds
Implementation Method 3
applying a compressive force through the bits
Data Source
Figure 1~2
AI summary
The contact has a metallic support (1) assembled in a precompressed contact chip (2). The contact chip includes a contact layer (8) with conducting agent made of silver whose weight percentage is between 92 to 99 percent of total mass, nickel whose weight percentage is between 0 to 3 percent and carbon whose weight percentage is between 0.5 to 5 percent. A reactive sub-layer (9) includes silver and copper based pseudo-alloy mixed with phosphorus based stripper agent, where fusion temperature of the sub-layer is lower than that of the contact layer. The contact layer includes a fraction of refractory particles such as tungsten carbide particles, tungsten particles and titanium nitride particles, an anti-soldering element such as nickel particles or graphite particles, or gas-producer elements such as carbon fibers. An independent claim is also included for a method for assembling a precompressed contact chip on a metallic support by direct sintering.