IC Card Viscous Layer for Flat Surface and Chip Strain Relief

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Solution Overview

Problem

Conventional IC cards experience surface irregularities and strain on the embedded IC chip due to the thickness mismatch between the IC chip and other components, leading to potential breakage and instability.

Innovation Solution

The IC card design incorporates a viscous layer with varying thickness and fusiform shape, allowing the module to be disposed parallel to the base materials without bending, and an adhesive layer is formed around the module, ensuring a flat surface and stable adhesion without strain on the IC chip.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If hot-melt adhesive agent is used to bond the module to the base material, then adhesion strength is improved, but the adhesive flows during hot-press treatment causing module position shift and surface irregularities

Engineering Contradiction:

Improveadhesion strengthVSAvoidmodule position precision

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

A positioning protrusion is introduced as an intermediary element between the module and the base material. This protrusion fits into a corresponding positioning recess, creating a mechanical positioning system that prevents module displacement during hot-press treatment while allowing the use of hot-melt adhesive for bonding.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The adhesive layer thickness is controlled to be within a specific range (0.01mm to 0.05mm) to prevent excessive adhesive flow during hot-press treatment. By optimizing the thickness parameter, the adhesive maintains sufficient bonding strength while minimizing position shift and surface irregularities.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If the IC chip thickness is greater than other components, then the IC chip can accommodate the circuit components, but surface irregularities occur and strain is applied to the IC chip

Engineering Contradiction:

ImproveIC chip component accommodationVSAvoidIC chip reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A viscous layer with spatially varying thickness is introduced beneath the module. The layer has greater thickness at the IC chip location (where thickness is 0.03mm to 0.08mm) to provide cushioning and strain relief, while being thinner in other areas to maintain overall flatness. This local variation in layer quality compensates for the IC chip thickness without causing surface irregularities.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The viscous layer acts as a pre-installed cushioning element that absorbs and distributes the strain caused by the IC chip thickness difference. This cushioning is built into the structure before the IC chip is subjected to operational stresses, preventing breakage and ensuring reliability.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If the module is not disposed parallel to the base materials, then thickness variation can be accommodated, but the IC chip may bend and break

Engineering Contradiction:

Improvethickness variation accommodationVSAvoidIC chip integrity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The viscous layer thickness is optimized to a specific range (0.03mm to 0.08mm at the IC chip location) that provides sufficient cushioning to absorb thickness variations while maintaining the module in a parallel disposition. This parameter optimization allows the system to adapt to thickness variations without compromising IC chip integrity.

Inventive Principle:

Principle #35Parameter changes

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 results in a stable IC card with a flat surface, preventing IC chip breakage and ensuring long-term reliability by maintaining the module's position during manufacturing and use.

Implementation Method 1

a viscous layer 21, 22 and 23 having a thickness that varies according to the thickness at each area of the module 12; the module 12 is disposed on a face 14a of the first base material 14 with interposition of the viscous layer 21, 22 and 23

Methodology Applied

Scientific EffectViscous layer cushioning effect:

Implementation Method 2

an adhesive layer 13 covering this module 12, a first base material 14 and second base material 15 sandwiching the module 12 with interposition of the adhesive layer 13

Methodology Applied

Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentEP2093704B1IC card and method for manufacturing the same

Publication Date: 2012.05.30 TOPPAN FORMS CO LTD

Figure 1A~2
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Figure 4~6

AI summary

This IC card is provided with a module having an inlet, an adhesive layer covering the module, and a first base material and second base material sandwiching the module with interposition of the adhesive layer. The module is disposed on one face of the first base material with interposition of a viscous layer which has a thickness that varies according to the thickness at each area of the module, and its two ends are narrower than its other parts when viewed from the outer face side of the first base material or the outer face side of the second base material. According to this IC card, it is possible to offer the IC card with a flat surface, and without occurrence of strain in the embedded IC chip.