Titanium Copper Foil Plating Structure for Solder Adhesion and Etching
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Solution Overview
Problem
Conventional titanium copper foils for autofocus camera modules face challenges with etching processability, adhesiveness to solder, and resistance to high temperature and humidity environments, leading to discoloration and reduced adhesive strength.
Innovation Solution
A titanium copper foil with a laminated structure comprising an underlying Cu plated layer and a Sn plated layer on its surface, enhancing resistance to acid or alkaline solutions and improving etching processability while maintaining high adhesive strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If titanium copper foil is used for spring materials in AFMs to reduce cost, then raw material cost is reduced, but etching processability and adhesiveness to solder deteriorate
Solution Approach 1:
The patent applies segmentation by dividing the protective coating into two distinct layers: a Cu plated layer (5-20 μm) and a Sn plated layer (1-10 μm). This layered structure separates the functions of etching resistance (Cu layer) and solder adhesion (Sn layer), allowing each layer to be optimized for its specific purpose while maintaining overall manufacturability
Solution Approach 2:
The patent uses composite materials by combining titanium copper base metal with a laminated plated layer structure. The composite consists of the Ti-Cu alloy substrate plus Cu and Sn plating layers, creating a multi-material system that exhibits properties superior to any single material, particularly in etching resistance and solder adhesion
2Device complexity
If conventional titanium copper foil is used without plated layer, then manufacturing simplicity is maintained, but resistance to discoloration and adhesive strength to solder are insufficient
Solution Approach 1:
The patent applies composite materials by combining titanium copper base metal with a laminated plated layer structure. The composite consists of the Ti-Cu alloy substrate plus Cu and Sn plating layers, creating a multi-material system that exhibits properties superior to any single material, particularly in etching resistance and solder adhesion
Solution Approach 2:
The patent applies preliminary action by pre-plating the titanium copper foil with Cu and Sn layers before etching and soldering processes. This preliminary protective and functional coating prevents discoloration during manufacturing and ensures good solder adhesion, addressing reliability issues before they arise
3Reliability
If Ni plated layer is used to prevent discoloration, then resistance to acid or alkaline solution is improved, but etching processability deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the protective coating into two distinct layers: a Cu plated layer (5-20 μm) and a Sn plated layer (1-10 μm). This layered structure separates the functions of etching resistance (Cu layer) and solder adhesion (Sn layer), allowing each layer to be optimized for its specific purpose
Solution Approach 2:
The patent applies parameter changes by selecting Cu and Sn as plating materials with specific thickness ranges (Cu: 5-20 μm, Sn: 1-10 μm). These parameter selections optimize the balance between chemical resistance, etching processability, and solder adhesion, overcoming the limitations of Ni plating
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 titanium copper foil with the laminated structure exhibits improved etching processability, resistance to discoloration, and increased adhesive strength, making it suitable for use as a spring material in autofocus camera modules.
Implementation Method 1
a plated layer in which an underlying Cu plated layer and a Sn plated layer have been laminated in this order on a surface of the base metal
Data Source
AI summary
The present invention provides a titanium copper foil having improved adhesion to solder and higher resistance to discoloration due to a high temperature and high humidity environment, an acid solution or an alkaline solution, and as well as having improved etching processability. The present invention provides a titanium copper foil comprising a base metal, the base metal having a composition containing Ti of from 1.5 to 5.0% by mass, the balance being copper and inevitable impurities, and having a thickness of from 0.018 to 0.1 mm, wherein the titanium copper foil has a plated layer in which an underlying Cu plated layer and a Sn plated layer have been laminated in this order on a surface of the base metal, and has an adhesive strength of 1 N or more as measured by a solder adhesive strength test according to the definition in the specification.