Stacked Spiral Inductive Touch Coils for Sensitivity

The patent transitions from planar U-shaped coils to three-dimensional stacked spiral coils. Multiple coil layers are stacked vertically, with each layer containing spiral-shaped coils that connect to X and Y metallic lines. This vertical stacking in the third dimension dramatically increases the number of coils within the same footprint area, resolving the contradiction between coil quantity and structural complexity.

The patent implements nested spiral coil structures where conductive material forms spiral patterns that are stacked and nested across multiple layers. Each spiral coil is connected through via holes to adjacent layers, creating a compact nested arrangement that maximizes coil density while maintaining electrical connectivity, thereby increasing the number of coils without proportionally increasing overall device volume.

The manufacturing process is segmented into distinct sequential steps: forming X and Y metallic line layers, creating insulation layers, depositing transparent conductive material for spiral coils, and establishing electrical connections through via holes. This segmentation of the manufacturing process into modular stages makes the complex multi-layer coil structure manufacturable by breaking down the complex task into manageable, repeatable steps.

The patent employs parameter changes in the manufacturing process, specifically using transparent conductive materials like ITO with controlled thickness and conductivity parameters. The spiral coil geometry parameters (pitch, radius, number of turns) are optimized to achieve desired sensing performance while maintaining manufacturability. These parameter optimizations balance the increased coil quantity with ease of manufacture.