Optical Filter Heat Resistance Squarylium Dye Reflow Soldering

Solution Overview

Problem

Optical filters used in imaging apparatuses face heat resistance issues during soldering by the reflow method, leading to thermal deterioration and appearance abnormalities due to the high temperatures affecting the near-infrared absorbing dyes and resins.

Innovation Solution

An optical filter with a squarylium dye having a thermal decomposition temperature of 265°C or higher and a resin with a glass transition temperature of 390°C or higher, ensuring excellent heat resistance and steep spectral transmittance changes near the boundary between visible and near-infrared light regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If soldering by reflow method is performed to achieve automated mounting and weight reduction, then productivity and ease of manufacture are improved, but the absorption layer containing organic dye and resin undergoes thermal deterioration at 260°C or higher

Engineering Contradiction:

Improveautomated mounting capabilityVSAvoidheat resistance of absorption layer

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the thermal parameters of the materials used in the absorption layer. Specifically, it selects a dye with a decomposition temperature of 265°C or higher and a resin with a glass transition temperature of 390°C or higher, thereby raising the thermal stability threshold of the absorption layer to withstand reflow soldering temperatures of 260°C or higher without deterioration.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite absorption layer by combining specifically selected dye and resin materials that together provide both the required optical properties (near-infrared absorption) and thermal stability. The composite structure allows the layer to resist thermal decomposition and maintain adhesiveness during high-temperature soldering processes.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If conventional dyes and resins are used in the absorption layer, then manufacturing cost is reduced, but thermal decomposition occurs generating bubbles and lowering adhesiveness to transparent substrate

Engineering Contradiction:

Improvemanufacturing costVSAvoidthermal decomposition effects

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent changes the thermal parameters of the materials used in the absorption layer. Specifically, it selects a dye with a decomposition temperature of 265°C or higher and a resin with a glass transition temperature of 390°C or higher, thereby raising the thermal stability threshold of the absorption layer to withstand reflow soldering temperatures of 260°C or higher without deterioration.

Inventive Principle:

Principle #35Parameter changes

3Object-generated harmful factors

If the optical filter is designed to shield near-infrared light effectively, then light shielding properties are improved, but the dye may be more susceptible to thermal deterioration at high temperatures

Engineering Contradiction:

Improvenear-infrared light shieldingVSAvoidthermal stability of dye

Core Design Contradiction:

Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent creates a composite absorption layer by combining specifically selected dye and resin materials that together provide both the required optical properties (near-infrared absorption) and thermal stability. The composite structure allows the layer to resist thermal decomposition and maintain adhesiveness during high-temperature soldering processes.

Inventive Principle:

Principle #40Composite materials

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 optical filter achieves excellent heat resistance and light shielding properties for near-infrared light, reducing thermal deterioration and appearance abnormalities during soldering, while maintaining high visible light transmittance and color reproducibility.

Implementation Method 1

the squarylium dye has a maximum absorption wavelength in 650 to 780 nm

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

the resin has a glass transition temperature of 390° C. or higher

Methodology Applied

Scientific EffectGlass transition:

Implementation Method 3

an optical filter, which transmits light in a visible region and shields light in a near-infrared region

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Data Source

PatentUS20220179141A1Optical filter and imaging device

Publication Date: 2022.06.09 AGC INC

AI summary

The present invention relates to an optical filter including an absorption layer containing a near-infrared absorbing dye and a resin, in which the near-infrared absorbing dye contains a squarylium dye having a maximum absorption wavelength in 650 to 780 nm and a thermal decomposition temperature of 265° C. or higher and satisfying IR20−IR80<65 nm, and the resin has a glass transition temperature of 390° C. or higher.