Ultrathin Chip-in-Coil Document Structure for Robust NFC Embedding
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Solution Overview
Problem
Conventional chips used in documents like banknotes are too small to accommodate an NFC antenna, too thick, and prone to breakage during production or use, limiting the available space for functionality and robustness.
Innovation Solution
A document structure with a ultrathin chip embedded between two paper layers, utilizing a Chip in Coil (CiC) arrangement, featuring a redistribution layer (RDL) for mechanical reinforcement and a flexible carrier with a metallization layer to support NFC communication, and a process that minimizes chip damage during handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a conventional chip is used, then the chip can be embedded in the document, but the chip is too small to accommodate an NFC antenna
Solution Approach 1:
The patent combines the chip and antenna into a single integrated structure where the antenna is formed directly on the chip substrate. This merging allows the NFC functionality to be achieved without requiring a separate antenna component, thus resolving the contradiction between limited chip area and the need for NFC capability.
Solution Approach 2:
The antenna structure is nested within the chip boundaries by forming it on the same substrate. The antenna traces are routed within the available chip area, effectively nesting the antenna function inside the chip footprint rather than requiring external space.
2Ease of operation
If a conventional chip arrangement is used, then the chip can provide functionality, but the arrangement is too thick
Solution Approach 1:
The patent employs a thin-film substrate for the chip that is flexible and can be laminated between paper layers. This thin-film approach reduces the overall thickness of the chip arrangement while maintaining electrical functionality, allowing the document to meet thickness requirements.
Solution Approach 2:
The patent transitions from a three-dimensional stacked chip arrangement to a planar two-dimensional layout where the antenna is formed on the chip surface. This dimensional change eliminates the need for vertical stacking, thereby reducing thickness while preserving functionality.
3Productivity
If a conventional chip arrangement is used, then the chip can be embedded, but it breaks down too quickly during production or use
Solution Approach 1:
The patent uses a composite structure consisting of the chip substrate, antenna traces, and protective paper layers laminated together. This composite construction provides mechanical reinforcement to the fragile chip and antenna elements, protecting them from breakage during high-speed production and subsequent use while maintaining productivity.
Solution Approach 2:
The chip and antenna structure is embedded between protective paper layers before the final document assembly is completed. This beforehand protection cushions the fragile electronic components against mechanical stresses during production handling and later use, preventing breakdowns without slowing down the production process.
4Strength
If two layers of paper are used for securing the chip, then mechanical manipulation is hampered, but only 20-40 μm remains for the chip layer
Solution Approach 1:
The patent utilizes an extremely thin flexible substrate for the chip that can be accommodated within the limited 20-40 μm space between the two protective paper layers. This thin-film approach allows the chip to fit within the constrained thickness while the outer paper layers provide the necessary mechanical security and manipulation resistance.
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 solution provides a cost-effective, robust, and functional document structure that meets thickness and durability requirements while enabling reliable NFC communication, reducing production defects and enhancing yield.
Implementation Method 1
The chip should be able to provide contactless communication, for example as near field communication (NFC), for example as a passive element that receives energy by means of near field communication
Data Source
AI summary
A method for producing a document structure, wherein the method includes producing a chip structure by forming a cavity in a carrier having a top side and an under side, picking up a chip having at least one chip contact and a redistribution layer (RDL) connected to the at least one chip contact by means of a picking-up device detaching the chip from an auxiliary carrier, wherein the chip bears on the auxiliary carrier by way of the RDL, wherein the chip is lifted up from the auxiliary carrier by means of pressure being exerted on the RDL, wherein the lifted-up chip is picked up and inserted into the cavity, and wherein the RDL is oriented on the top side of the carrier, fixing the chip in the cavity by means of an adhesive, electrically conductively connecting the at least one chip contact of the RDL to an electrically conductive region of the carrier by means of an electrically conductive material, and embedding the carrier between a first paper layer and a second paper layer.