RFID Tag IC Bonding Using Solder Antenna and Hot Melt Adhesive

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Solution Overview

Problem

Current methods for manufacturing RFID tags using isotropically or anisotropically conductive adhesives are costly, require precise curing processes, are sensitive to transportation, and contain environmentally unfriendly chemicals, with limited shelf life and long curing times.

Innovation Solution

The method involves using a soldering material antenna covered with hot melt adhesive, heating it to melt, placing an IC with melted adhesive, establishing an electrical connection, and cooling to create a soldered joint surrounded by solidified adhesive, which provides mechanical strength without the need for expensive conductive adhesives.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If isotropically or anisotropically conductive adhesive is used to connect IC to antenna, then electrical connection is established, but manufacturing cost increases and curing process becomes complex

Engineering Contradiction:
Improveelectrical connectionVSAvoidcuring process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the fundamental parameter of the adhesive material from conductive adhesive requiring chemical curing to non-conductive adhesive cured by thermal melting and solidification. This parameter change eliminates the need for complex curing processes including pressure, temperature control, and time management, while maintaining reliable electrical connection through the soldering material antenna

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces expensive conductive adhesive with a cheaper non-conductive adhesive that does not require sophisticated curing equipment. The adhesive is applied in solid form, melted during bonding, and solidifies to provide mechanical strength, eliminating the need for costly curing processes and equipment

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Reliability

If conductive adhesive is used for IC connection, then electrical connection is achieved, but manufacturing time increases due to curing requirements

Engineering Contradiction:
Improveelectrical connectionVSAvoidmanufacturing speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent changes the curing mechanism from chemical reaction requiring 6-10 seconds under controlled conditions to physical phase change (melting and solidification) that occurs rapidly at the melting point temperature. This parameter change dramatically reduces the bonding time and eliminates the need for separate curing steps, thereby increasing manufacturing productivity

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If conventional adhesive materials are used, then IC to antenna bonding is achieved, but environmental harm increases due to toxic chemicals

Engineering Contradiction:
Improvebonding processVSAvoidenvironmental pollution
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent replaces hazardous conductive adhesives containing toxic chemicals like epoxies with biodegradable non-conductive adhesives. The new adhesive materials are environmentally friendly, do not require harmful solvents or curing agents, and can be disposed of safely, thereby eliminating environmental pollution while maintaining ease of manufacture

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent converts the previously harmful characteristic of requiring complex curing processes into a benefit by using thermal melting and solidification. This phase change process eliminates the need for toxic chemicals and harmful solvents, transforming an environmental liability into an environmentally friendly manufacturing process

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

4Quantity of substance

If hot melt adhesive is used instead of conductive adhesive, then material cost decreases, but electrical conductivity must be provided by alternative means

Engineering Contradiction:
Improveadhesive material costVSAvoidelectrical connection
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent applies multi-functionality to the antenna by making it not only the RF signal conductor but also the electrical connection path for the IC. The soldering material antenna serves dual purposes: maintaining RF performance and providing electrical connectivity, thereby eliminating the need for expensive conductive adhesive while ensuring reliable electrical connection

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 reduces curing time, lowers costs, eliminates the need for precise temperature control, and uses environmentally friendly materials with longer shelf life, while ensuring a strong and reliable electrical connection between the IC and antenna.

Implementation Method 1

heating the antenna to a temperature above its melting point, wherein the heated parts of the antenna and the hot melt adhesive melt

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

cooling the RFID tag, such that the hot melt adhesive and the antenna solidify

Methodology Applied
Scientific EffectSolidification: Freezing

Data Source

PatentEP3704635B1Method for manufacturing an RFID tag and an RFID tag comprising an IC and an antenna
Publication Date: 2024.11.27 DIGITAL TAGS FINLAND OY

AI summary

Method for manufacturing an RFID tag comprising an IC and an antenna. The method comprising the steps of providing an antenna made of a soldering material,which antenna is at least partly covered with a hot melt adhesive in solid form; heating the antenna to a temperature above its melting point, wherein the heated parts of the antenna and the hot melt adhesive melt,placing an IC in a predetermined position which position is suitable for the IC to connect to the antenna; pressing the IC and antenna together, such that, an electrical connection between the IC and the antenna is established; and cooling RFID tag, such that the hot melt adhesive and the antenna solidify, wherein a soldered joint between the IC and the antenna is achieved and the hot melt adhesive surrounds the joint between the IC and the antenna.