Electrical Probe Alignment for Transparent Substrates
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Solution Overview
Problem
Conventional alignment methods for multi-layer articles with transparent or substantially transparent materials face challenges due to lack of optical contrast, making it difficult to align patterns optically, especially when the alignment marks have poor optical contrast with the substrate.
Innovation Solution
The use of electrical measurements to identify the location of alignment structures on substrates with poor optical contrast, employing resistance or capacitance probes to differentiate between the substrate and alignment features, allowing for precise alignment of subsequent patterns based on measured electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If optical alignment methods are used, then alignment precision can be achieved for opaque materials, but alignment becomes difficult or impossible for transparent materials due to lack of optical contrast
Solution Approach 1:
The patent replaces optical alignment methods with electrical measurement methods. Instead of using optical sensors to detect alignment marks, the system uses electrical probes to measure electrical characteristics (such as capacitance or resistance) at different positions on the substrate, thereby identifying the locations of alignment marks through electrical contrast rather than optical contrast.
Solution Approach 2:
The patent changes the detection parameter from optical properties (reflectance, absorption) to electrical properties (capacitance, resistance). By measuring electrical characteristics at multiple positions and identifying locations where these characteristics differ from the surrounding substrate, the system can detect alignment marks on transparent materials that are invisible to optical methods.
2Manufacturing precision
If alignment marks are placed at outside margins for improved angular registration, then registration accuracy improves, but the alignment marks cannot be removed in the finished multi-layer article
Solution Approach 1:
The patent creates local electrical contrast by forming alignment marks with different electrical characteristics than the surrounding substrate. This can be achieved by using conductive materials on insulating substrates or vice versa, allowing the alignment marks to be electrically distinct from their local environment while being positioned at optimal locations for registration accuracy.
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
Enables accurate alignment of patterns on transparent or substantially transparent materials by utilizing electrical contrast, overcoming the limitations of optical alignment methods and ensuring registration within tight tolerances, applicable to various applications including touch-screens and photovoltaic devices.
Implementation Method 1
measuring an electrical characteristic such as resistance
Implementation Method 2
measuring an electrical characteristic such as capacitance
Data Source
AI summary
A system for aligning a first and second pattern based on alignment structures is disclosed. The system comprises a first substrate including the first alignment structure. The alignment structure has a different magnitude of the electrical characteristic than the substrate. The system also includes an electrical probe and a controller for controlling the relative position of the probe with respect to the substrate to measure the electrical characteristic at a plurality of positions proximate the substrate. The measured electrical characteristics are used to identify the location of the alignment structure by identifying a difference between the measured electrical characteristic at pairs of the plurality of positions. A controller identifies the location of a second alignment structure formed on a second substrate. A registration mechanism aligns the two substrates using the identified locations of the first and second alignment structures.