Titanium-Copper Alloy Plating for Solder Adhesion
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Solution Overview
Problem
Titanium-copper alloys used in autofocus camera modules exhibit low adhesion strength with solder, which affects the reliability of the joined parts and requires improvement for both adhesion and etching properties.
Innovation Solution
A titanium-copper alloy with a plating layer, specifically a Ni plating, Co plating, or Co-Ni alloy plating, is applied to enhance solder adhesion and etching properties, where the plating layer thickness is optimized to achieve significant improvements in adhesion strength and maintain excellent etching properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If titanium-copper alloy is used as spring material for AFM, then material cost is reduced compared to Cu-Ni-Sn alloy, but adhesion strength with solder becomes low
Solution Approach 1:
The invention applies a plating layer (Ni, Co, or Co-Ni alloy) on the titanium-copper alloy surface, creating a composite structure that combines the low-cost titanium-copper base material with a solder-adhesive plating layer, thereby reducing overall material cost while ensuring high adhesion strength with solder
Solution Approach 2:
The plating layer acts as an intermediary between the titanium-copper alloy and the solder, mediating the adhesion interface. The plating layer provides good adhesion to both the base material and the solder, solving the low adhesion problem without requiring changes to the cost-effective titanium-copper alloy composition
2Reliability
If plating layer is applied to improve solder adhesion, then adhesion strength increases, but etching properties may deteriorate
Solution Approach 1:
The invention optimizes plating layer parameters including thickness (1 μm or less) and composition (Ni, Co, or Co-Ni alloy with specific ratios) to achieve the balance between solder adhesion and etching properties. By controlling these parameters, the plating layer provides sufficient adhesion while maintaining etchability for spring material fabrication
Solution Approach 2:
The plating layer is applied selectively on the surface of the titanium-copper alloy, providing localized solder adhesion enhancement only where needed for joining, while the bulk material retains its etching properties. The plating thickness is controlled to be thin (1 μm or less) to preserve etching capability in areas requiring fabrication
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 alloy with a plating layer achieves adhesion strength 10 times or more than conventional methods, ensuring reliable soldering and maintaining excellent etching properties, making it suitable for use as a spring material in autofocus camera modules.
Implementation Method 1
a plating layer provided on a surface of the base material, wherein the plating layer is selected from the group consisting of a Ni plating layer, a Co plating layer, and a Co—Ni alloy plating layer
Implementation Method 2
it has been found that a diffusion layer of Cu—Sn—Ti is formed by the heat from soldering to a titanium-copper alloy and that the diffusion layer causes significant reduction in adhesion
Data Source
AI summary
There is provided a titanium-copper alloy in which the adhesion strength with solder can be increased. The titanium-copper alloy comprises a base material and a plating layer provided on a surface of the base material, wherein the base material contains 1.5 to 5.0% by mass of Ti with a balance consisting of copper and unavoidable impurities, and the plating layer is selected from the group consisting of a Ni plating layer, a Co plating layer, and a Co—Ni alloy plating layer.