RFID Card Transparent Window Lamination Method

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Solution Overview

Problem

The existing methods for manufacturing RFID cards with transparent windows often result in defects due to material collapse during lamination, especially when an inner layer with an opening is covered by thicker layers, leading to uneven surfaces and increased production costs.

Innovation Solution

A method involving a pre-lamination step where a second layer with a recess is formed to create a raised portion, which is then placed over the opening in the first layer, ensuring the raised portion fills the opening during lamination, preventing material collapse and maintaining a flat surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If layers are laminated together with heat and pressure to form an inlay, then the layers are joined together, but material collapse occurs in the region where the opening is located, resulting in defective inlays with uneven surfaces

Engineering Contradiction:
Improvebonding strengthVSAvoidsurface flatness
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The method applies a preliminary lamination step before the final lamination. In this first lamination step, the inlay is laminated onto the support layer at a first position, creating a raised portion that will later fill the opening. This preliminary action prepares the structure to prevent material collapse during subsequent lamination steps.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The lamination process is divided into multiple separate steps rather than being performed in a single operation. The first lamination step creates the raised portion, while subsequent steps complete the lamination. This segmentation allows the raised portion to be properly formed and positioned to prevent material collapse in the opening region.

Inventive Principle:
Principle #1Segmentation

2Length of stationary object

If the thickness of the inner layer is larger than the thickness of the covering layers, then the opening can be better supported, but material still flows into the opening during lamination, causing local collapse and defective surfaces

Engineering Contradiction:
Improvelayer thicknessVSAvoidsurface uniformity
Core Design Contradiction:
Length of stationary objectVSManufacturing precision

Solution Approach 1:

The raised portion is created in advance through the first lamination step, before the final lamination occurs. This preliminary formation of the raised portion ensures that when the opening is covered in subsequent steps, there is already material in place to prevent collapse, regardless of the relative thicknesses of the layers.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The raised portion acts as an intermediary element between the opening and the covering layers. It provides structural support and prevents direct material flow from the covering layers into the opening, thereby preventing local collapse and maintaining surface uniformity.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If a filling part is added in the opening to support the cover layers, then material flow and surface collapse are prevented, but the manufacturing process becomes more complex and costly

Engineering Contradiction:
Improvesurface flatnessVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The method eliminates the need for separate filling parts by using the inlay material itself to form the raised portion that fills the opening. The filling function is extracted from being a separate component and integrated into the inlay structure through the preliminary lamination step, thereby simplifying the manufacturing process.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The inlay serves its own filling function by forming the raised portion from its own material during the preliminary lamination step. Instead of requiring an external filling part to be added, the inlay creates its own structural support, reducing manufacturing complexity and costs.

Inventive Principle:
Principle #25Self-service

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 simplifies and stabilizes the production process, reducing defects and costs by ensuring an even surface on the final product, applicable to various layer configurations including those with RFID transponders and multiple layers.

Implementation Method 1

they are laminated together with heat and pressure

Methodology Applied
Scientific EffectHeat and pressure lamination:

Implementation Method 2

the material of both cover layers 1 and 2 filling the opening 4 as a result of the heat and pressure applied in the lamination step

Methodology Applied
Scientific EffectMaterial flow:

Data Source

PatentEP3421235B1Method of manufacturing cards with a transparent window
Publication Date: 2024.03.20 HID GLOBAL CID SAS
  • EP3421235B1 patent drawingFigure 1~4
  • EP3421235B1 patent drawingFigure 5~6
  • EP3421235B1 patent drawingFigure 7

AI summary

The method comprises a pre-lamination step wherein a layer is placed in contact at least on one side with a lamination plate having a recess and the layer undergoes lamination such that a raised portion is formed on the layer; an assembling step wherein another layer is placed in contact with the layer, and the raised portion of the layer is at least partially placed in an opening of the other layer; and a lamination step wherein said layers are laminated together.