Silver-Tin Plating Reflow Using Infrared Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for producing silver-plated products with tin-plating films on terminal parts, such as connectors, often result in increased contact resistance and surface color changes after reflow treatment, and require costly low-oxygen atmosphere heating or excessive peeling processes.
Innovation Solution
A method involving forming a nickel-plating film on a copper or copper alloy base material, followed by a silver-plating film on one portion and a tin-plating film on another, with infrared radiation used to reflow-treat the tin-plating film without melting it, thereby maintaining low contact resistance and surface color stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reflow treatment is carried out after tin plating to suppress whisker occurrence and reduce resistance, then reliability is improved, but contact resistance increases and surface color changes occur
Solution Approach 1:
The invention changes the heating method from conventional furnace heating to infrared radiation heating, and controls the heating temperature to be below the melting point of tin (232°C). This parameter change allows reflow treatment to suppress whiskers while preventing excessive oxidation that causes contact resistance increase and color change
Solution Approach 2:
The invention performs reflow treatment in an inert atmosphere (nitrogen or vacuum) to prevent oxidation of the tin-plated surface. This inert environment prevents the formation of oxide layers that would increase contact resistance and alter surface color, while still allowing the tin to be softened for good adhesion
2Reliability
If reflow treatment is carried out after tin plating to reduce resistance, then electrical characteristics are improved, but production cost increases due to low-oxygen atmosphere requirement
Solution Approach 1:
The invention replaces the conventional furnace heating system with an infrared radiation heating system. This substitution eliminates the need for complex low-oxygen atmosphere control in furnaces, as infrared heating can be performed more simply with localized heating, thereby reducing production costs while maintaining electrical characteristics
Solution Approach 2:
By changing the heating method to infrared radiation and controlling temperature below tin's melting point, the invention achieves reflow treatment with simpler equipment requirements, reducing production costs while still improving electrical characteristics through whisker suppression
3Reliability
If tin plating is applied to aluminum or aluminum alloy for swaging portions, then corrosion resistance is improved, but resistance value becomes high requiring reflow treatment
Solution Approach 1:
The invention changes the heating parameters to infrared radiation with temperature control below 232°C (tin's melting point). This allows the tin-plated aluminum to undergo reflow treatment that reduces resistance value while maintaining the corrosion resistance provided by the tin plating layer
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 approach produces an inexpensive plated product with contact resistance not exceeding 1 mΩ and prevents surface color changes, reducing production costs and improving reliability.
Implementation Method 1
irradiating with infrared rays to heat the surface
Data Source
AI summary
There is provided an inexpensive plated product, which can prevent the increase of the contact resistance of a silver-plating film and the change of the color of the surface thereof after reflow-treating a plated product wherein the silver-plating film is formed on a portion of the surface thereof and wherein a tin-plating film is formed on a portion of the other portion of the surface thereof, and a method for producing the same. The plated product is produced by a method including the steps of: forming a nickel-plating film 12 on a surface of a base material 10 of copper or a copper alloy; forming a silver-plating film 16 on a portion of a surface of the nickel-plating film 12, and forming a tin-plating film 20 on a portion of the other portion of the surface of the nickel-plating film 12, to prepare a plated product which has the silver-plating film 16 and the tin-plating film 20 on the surface of the nickel-plating film 12 formed on the base material 10; and irradiating the surface of the plated product with infrared rays to heat the surface thereof to reflow-treat the tin-plating film 20 to cause the tin-plating film 20 to be a reflowed tin-plating layer 22.