Phosphor-Loaded Waveguide for Secure PCB Authentication
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Solution Overview
Problem
Conventional waveguides used in printed circuit boards for creating unique digital identifiers are difficult to manufacture and require complex processes, and their light patterns are not significantly affected by the insertion of probes, making them less secure for authentication purposes.
Innovation Solution
A waveguide design incorporating a luminescent material along its perimeter or within its layers, which emits additional light and increases the sensitivity of the light pattern to probe insertions by altering the light path and production of secondary light, enhancing the uniqueness and detectability of the identifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional waveguide construction methods are used with inner core and outer cladding, then the waveguide structure is simple to manufacture, but the light pattern is not significantly affected by probe insertion reducing security
Solution Approach 1:
The patent applies composite materials by combining the traditional inner core and outer cladding with a luminescent material layer. This composite structure creates multiple light paths - both direct light transmission and luminescent material-mediated light paths - which significantly increases the sensitivity to probe insertion while maintaining manufacturability through layered construction
Solution Approach 2:
The luminescent material acts as an intermediary between the light source and the final light pattern. When light passes through or near the luminescent material, it creates additional light paths and patterns that are highly sensitive to probe insertion, thereby enhancing security without requiring complete redesign of the waveguide structure
2Reliability
If luminescent material is added to the waveguide, then the light pattern sensitivity to probe insertion is significantly improved, but the manufacturing process becomes more complex
Solution Approach 1:
The waveguide is segmented into distinct functional layers: the inner core for light transmission, the outer cladding for structural definition, and the luminescent material layer for enhanced sensitivity. This segmentation allows each layer to be optimized independently and manufactured using standard layered PCB processes
Solution Approach 2:
The patent utilizes parameter changes by selecting luminescent materials with specific emission characteristics and positioning them at optimal locations within the waveguide structure. This allows tuning of the light pattern sensitivity without fundamental changes to the manufacturing process
3Productivity
If traditional manufacturing processes are used for creating unique digital identifiers, then the manufacturing is straightforward, but creating unique and uncopyable identifiers is difficult and time consuming
Solution Approach 1:
The waveguide structure with luminescent material provides self-service for unique identifier generation. The physical variations in the manufactured waveguide structure automatically create unique light patterns that serve as uncopyable identifiers, eliminating the need for additional programming or configuration steps
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 luminescent material significantly changes the reflected light pattern upon probe insertion, improving the security and uniqueness of the digital identifier, making it more difficult to replicate or access without authorization.
Implementation Method 1
A luminescent material may be disposed along the outer edge of these layers. When light from within the waveguide strikes the luminescent material, it emits light, thereby adding to the light in the waveguide.
Implementation Method 2
The luminescent material may be a phosphor.
Implementation Method 3
Light is reflected at the boundary between the inner core 21 and the outer cladding 22 or at the boundary between the outer cladding 22 and the silver layer 24.
Implementation Method 4
The inner core 21 may have a higher refractive index (n) than the outer cladding 22. For example, the inner core 21 may have a refractive index of 1.59, while the outer cladding has a refractive index of 1.49.
Implementation Method 5
an absorptive layer of material 25 absorbs the light in the outer cladding 22
Implementation Method 6
Light in the inner core 21 is not coupled to the image sensor 12, but inhomogeneities 27 in the inner core 21 scatter light into the outer cladding 22 where some fraction of this light is received by the image sensor 12.
Data Source
AI summary
An improved waveguide is disclosed. The waveguide utilizes a luminescent material disposed within or around its perimeter to introduce additional light into the waveguide. For example, the waveguide may include a plurality of planar layers having different refractive indexes. A luminescent material may be disposed along the outer edge of these layers. When light from within the waveguide strikes the luminescent material, it emits light, thereby adding to the light in the waveguide. Not only does the luminescent material introduce more light into the waveguide, it also introduces more light sources, thereby making it more difficult to introduce a probe without blocking at least a portion of the light destined for the image sensor. The luminescent material may be a phosphor.