Micro-speaker Pad Plating Segmentation for Welding Quality
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Solution Overview
Problem
Existing micro-speakers face challenges in miniaturization due to the inconsistent thickness of the plating layer on flexible circuit boards, leading to a risk of pseudo welding during spot welding of voice coil lead wires, which affects the quality and reliability of the audio equipment.
Innovation Solution
The micro-speaker design incorporates a pad on the flexible circuit board with a first plating layer of greater thickness than the second plating layer, allowing for effective penetration and coverage of the lead wire, thereby preventing pseudo welding and enhancing the connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single uniform plating layer is used on the flexible circuit board, then the manufacturing process is simple, but the spot welding quality is poor due to inability to meet both penetration and coverage requirements
Solution Approach 1:
The plating layer is segmented into two distinct layers: a first plating layer with thickness of 0.5-1.5μm for insulation penetration, and a second plating layer with thickness of 1.5-3.0μm for coverage and welding quality. This segmentation allows each layer to fulfill specific functional requirements that cannot be met by a uniform thickness design.
Solution Approach 2:
Different regions of the plating layer are assigned different thicknesses to meet local requirements. The first plating layer provides localized thin coverage for effective insulation penetration during spot welding, while the second plating layer provides thicker coverage in areas requiring enhanced welding quality and lead wire coverage.
2Manufacturing precision
If the plating layer is made thin for insulation penetration, then the penetration effect is good, but the coverage and welding quality deteriorate
Solution Approach 1:
The plating layer is divided into two functional segments: the first plating layer (0.5-1.5μm) optimized for insulation penetration with precise thin thickness control, and the second plating layer (1.5-3.0μm) optimized for welding quality with greater thickness for robust coverage.
Solution Approach 2:
The thickness parameter of the plating layer is changed across different layers. The first plating layer uses a thinner thickness parameter (0.5-1.5μm) to achieve effective insulation penetration, while the second plating layer uses a thicker parameter (1.5-3.0μm) to ensure adequate coverage and welding reliability.
3Reliability
If the plating layer is made thick for coverage, then the coverage effect is good, but the insulation penetration capability deteriorates
Solution Approach 1:
The plating structure is segmented into two layers with different thicknesses. The first plating layer (0.5-1.5μm) provides thin coverage that allows effective insulation penetration, while the second plating layer (1.5-3.0μm) provides thick coverage for enhanced lead wire protection and welding quality.
Solution Approach 2:
Different thickness qualities are assigned to different plating layers. The first plating layer has a thinner local quality characteristic (0.5-1.5μm) optimized for penetration precision, while the second plating layer has a thicker local quality characteristic (1.5-3.0μm) optimized for coverage and welding reliability.
Data Source
AI summary
A micro-speaker is provided, including: a vibration unit and a fixed unit. The vibration unit includes a diaphragm, a voice coil located below the diaphragm and driving the diaphragm to vibrate and emit sound, and a flexible circuit board connected to the voice coil. The diaphragm and the flexible circuit board are fixed to the fixed unit. The voice coil includes a body and a lead wire extending from the body. A pad is formed on the flexible circuit board, and includes a base and a plating layer formed on the base. The plating layer includes a first plating layer and a second plating layer extending from the first plating layer. The first plating layer has a greater thickness than the second plating layer. An end of the lead wire away from the body is welded to the pad and covered by the second plating layer.