Stacked RFID Inductor Modules with Conductive Adhesive
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Solution Overview
Problem
Existing antenna designs for radiofrequency identification (RFID) systems fail to achieve high inductance values, typically requiring microHenries, while maintaining a small size and low cost, as they only achieve low values of inductance, such as a few nanoHenries.
Innovation Solution
The integration of multiple BGA/LGA substrates with conductive adhesive regions for both mechanical and electrical connections, allowing for the stacking of modules with multiple metallization layers to achieve higher inductance values, with each module forming a coil and using conductive glue or solder paste for coupling, enabling a simple layout and reduced area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a miniaturized loop antenna is formed on a BGA/LGA substrate using conventional single-layer or multi-layer PCB techniques, then the device complexity and manufacturing process are relatively simple, but the inductance value is limited to only a few nanoHenries
Solution Approach 1:
The patent transitions from planar 2D PCB traces to 3D stacked modular coils, utilizing the vertical dimension to multiply inductance. By stacking multiple modules with metallization layers separated by insulating layers, the inductance increases from nanoHenries to microHenries while maintaining manufacturing simplicity through standardized module assembly.
Solution Approach 2:
The patent employs composite structures combining conductive metallization layers with insulating material layers in a stacked configuration. Each module integrates copper or aluminum traces with dielectric materials, and the stacked assembly creates a composite electromagnetic structure that achieves high inductance values while maintaining electrical isolation between layers.
2Reliability
If multiple substrates or modules are superimposed to increase inductance value, then the inductance can reach microHenry range, but the device complexity and manufacturing complexity increase
Solution Approach 1:
The patent divides the high-inductance antenna into multiple identical or similar modules, each containing a subset of the total inductance. These modules are stacked vertically with standardized interfaces, allowing the complex high-inductance structure to be assembled from simpler, repeatable units. This segmentation reduces design complexity and enables modular manufacturing.
Solution Approach 2:
The patent combines multiple separate modules into a unified stacked structure where the metallization layers of adjacent modules are electrically connected through conductive vias or contact pads. This merging of modules creates a continuous current path through all layers, achieving the cumulative inductance effect while maintaining the benefits of modular construction.
3Reliability
If more metallization layers are added to each module to increase inductance, then the inductance value increases, but the manufacturing precision requirements and cost increase
Solution Approach 1:
The patent achieves the required inductance value by stacking multiple modules with a moderate number of metallization layers (e.g., 2-4 layers per module), rather than attempting to achieve the full inductance in a single complex layer. This partial action approach distributes the inductance requirement across multiple simpler layers, reducing the precision demands on each individual metallization layer while achieving the cumulative inductance target.
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 allows for the attainment of inductance values on the order of one microHenry with a compact footprint and reduced manufacturing costs, effectively addressing the limitations of prior art by enhancing both mechanical and electrical connections.
Implementation Method 1
first adhesive conductive region that achieves the mechanical connection with an adjacent substrate (module)
Implementation Method 2
second adhesive conductive region that achieves the electric connection with the coil formed in the adjacent substrate (module)
Implementation Method 3
an inductor device that overcomes the drawbacks of the prior art... an inductance value on the order of microHenries (μH)
Data Source
AI summary
An embodiment of integrated inductor device, comprising a plurality of modules overlaid to each other, each module including at least one coil of conducting material. The directly overlaid pairs of coils are coiled in opposite directions. The directly overlaid modules are mechanically coupled through first adhesive conductive regions and the coils of the directly overlaid modules are electrically coupled to each other through second adhesive conductive regions. The first and the second adhesive conductive regions coupling directly overlaid modules are formed in the same step of the process, are of the same material and are arranged at a same level.