RFID Inlay Thinning via Direct Chip Bonding

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Solution Overview

Problem

Current methods for manufacturing high-frequency RFID inlays with smaller chips are limited by the need for larger chip modules, which restrict the thickness of the inlays due to the use of chip modules that are much heavier and larger than single chips, making it difficult to achieve thinner inlays.

Innovation Solution

A method of direct bonding a chip to an embedded wire antenna within a substrate, using a tooling system that holds the chip from one side and connects the antenna wires through a welding head from the other side, allowing for thermo-compression bonding and embedding the wire antenna completely within the support layer to achieve a monolayer thickness thinner than the sum of the chip and antenna thicknesses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If chip modules are used to manufacture high-frequency RFID inlays, then the inlays can be produced with established methods, but the inlay thickness increases due to the larger size and weight of chip modules compared to single chips

Engineering Contradiction:
ImprovemanufacturabilityVSAvoidinlay thickness
Core Design Contradiction:
Ease of manufactureVSLength of moving object

Solution Approach 1:

The invention extracts the chip from its traditional module configuration and bonds it directly to the antenna substrate. This removes the unnecessary module housing and additional layers, achieving thinner inlays while maintaining manufacturability through direct bonding processes

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention transitions from a modular three-dimensional structure to a planar two-dimensional integration by bonding the chip directly to the antenna substrate surface, eliminating vertical layering and achieving reduced thickness

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If chip modules are used for RFID inlays, then production can proceed with current technology, but the inlay thickness cannot be reduced below the module dimensions

Engineering Contradiction:
Improveproduction capabilityVSAvoidinlay thickness
Core Design Contradiction:
ProductivityVSLength of moving object

Solution Approach 1:

The invention replaces the mechanical module structure with a direct bonding approach, using thermal and mechanical pressure during bonding to achieve permanent attachment, thereby enabling thinner inlays while maintaining production efficiency

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention merges the chip and antenna substrate into a single integrated structure through direct bonding, eliminating the separation inherent in module-based construction and achieving reduced overall thickness

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If wire antenna ends are left protruding for connection, then the antenna can be properly positioned, but the inlay thickness increases and additional carrier layers are required

Engineering Contradiction:
Improveconnection easeVSAvoidinlay thickness
Core Design Contradiction:
Ease of operationVSLength of moving object

Solution Approach 1:

The invention performs preliminary positioning of the wire antenna ends during the embedding process, ensuring they are correctly located before chip bonding occurs, thereby eliminating the need for protruding ends and additional carrier layers

Inventive Principle:
Principle #10Preliminary action

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 enables the production of thinner high-frequency RFID monolayers, eliminating the need for additional carrier layers and achieving a final thickness corresponding to the chip and wire ends, with the potential for even thinner inlays by flattening the wire connections for improved conductivity.

Implementation Method 1

allowing for thermo-compression bonding and embedding the wire antenna completely within the support layer

Methodology Applied
Scientific EffectThermo-compression bonding:

Implementation Method 2

firstly an antenna is applied to the substrate via a wiring device using ultrasound to attach the wire to the substrate

Methodology Applied
Scientific EffectUltrasound: Ultrasound

Data Source

PatentEP2873031B1Method of manufacturing a functional inlay
Publication Date: 2018.08.22 ASSA ABLOY AB
  • EP2873031B1 patent drawingFigure 1~3
  • EP2873031B1 patent drawingFigure 4~5
  • EP2873031B1 patent drawingFigure 6~8

AI summary

The method of manufacturing a functional inlay comprises the steps of: -) providing a support layer with at least a first and a second side -) embedding a wire antenna in said support layer -) processing said support layer with said embedded wire antenna to a connection station in which -) said support layer is approached on said first side by a holding device holding a chip with a surface comprising connection pads; -) said support layer is approached on said second side by a connection device; and -) said antenna wire is connected to said connection pads by means of a reciprocal pressure exerted between said holding device and said connection device.