Optical Semiconductor Package With Femtosecond Laser Air Gap Reflector

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Solution Overview

Problem

Existing optical semiconductor packages face challenges in achieving high light use efficiency while maintaining a compact, low-profile design, as previous solutions like metallic reflectors, extended sealing layer portions, and spherical structures either increase manufacturing complexity, accuracy issues, or insufficiently control light reflection.

Innovation Solution

The use of a cylindrical air gap formed within the optical transparency sealing layer by femtosecond laser processing, which acts as a built-in reflector to enhance light takeoff efficiency without increasing component count or complexity, allowing for precise positioning and improved manufacturing accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a metallic reflector is buried in the optical transparency sealing layer, then light takeoff efficiency is improved, but manufacturing cost increases and device profile increases

Engineering Contradiction:

Improvelight takeoff efficiencyVSAvoidmanufacturing process complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent extracts the reflector function from a separate metallic component and integrates it directly into the optical transparency sealing layer through laser processing. The laser creates a reflective interface by modifying the sealing layer material itself, eliminating the need for a separate metallic reflector component and simplifying the manufacturing process.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the reflector function with the optical transparency sealing layer by creating a laser-induced reflective interface within the sealing layer material. This combines the sealing function and the light reflection function into a single integrated structure, reducing component count and manufacturing complexity.

Inventive Principle:

Principle #5Merging (Combining)

2Loss of energy

If a metallic reflector is used, then light reflection is improved, but bonding wire routing becomes complicated and profile increases

Engineering Contradiction:

Improvelight reflection efficiencyVSAvoidbonding wire routing

Core Design Contradiction:

Loss of energyVSEase of operation

Solution Approach 1:

The reflector function is merged into the sealing layer, allowing bonding wires to be routed freely without avoiding separate reflector components. The laser-induced reflective interface is created within the sealing layer material itself, eliminating spatial conflicts with bonding wire routing.

Inventive Principle:

Principle #5Merging (Combining)

3Length of stationary object

If the reflector height is reduced to accommodate bonding wires, then profile is improved, but light reflection amount decreases

Engineering Contradiction:

Improvepackage profileVSAvoidlight reflection amount

Core Design Contradiction:

Length of stationary objectVSLoss of energy

Solution Approach 1:

The patent replaces the mechanical reflector structure with a laser-induced optical interface within the sealing layer. This substitution allows the reflective function to be achieved without the height constraints of traditional mechanical reflectors, maintaining low profile while preserving light reflection efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical state of the sealing layer material through laser processing, creating a reflective interface by modifying the material's optical properties. This parameter change allows the reflective function to be achieved within the sealing layer without requiring additional height.

Inventive Principle:

Principle #35Parameter changes

4Loss of energy

If spherical structures are buried in the sealing layer, then light takeoff efficiency is improved by refraction and diffraction, but manufacturing accuracy becomes difficult to control

Engineering Contradiction:

Improvelight takeoff efficiencyVSAvoidassembly position accuracy

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The patent extracts the light control function from separate spherical structures and integrates it directly into the sealing layer through laser processing. The laser creates the reflective interface at the exact position needed, eliminating assembly position accuracy issues associated with burying separate spherical components.

Inventive Principle:

Principle #2Taking out (Extraction)

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 creation of a compact, low-profile optical semiconductor package with significantly improved light use efficiency, allowing for longer detection distances and enhanced component detection, while simplifying manufacturing and reducing costs.

Implementation Method 1

an interface in the optical transparency sealing layer which acts as a reflector

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

cylindrical air gap formed within the optical transparency sealing layer by femtosecond laser processing

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentEP2688115B1Optical semiconductor package, optical semiconductor module, and manufacturing method of these

Publication Date: 2019.06.12 OMRON CORP

Figure 1
Figure 2(A)~2(C)
Figure 3~4

AI summary

This optical semiconductor package (1A) is provided with an interposer (10), an LED chip (20) arranged on a principal surface (10a) of the interposer (10) and emitting light, and an optical transparency sealing layer (30) which covers the principal surface (10a) of the interposer (10) and seals the LED chip (20). Inside of the optical transparency sealing layer (30), a cylindrical air gap (31) surrounding the optical axis of the LED chip (20) is formed by a laser processing using an ultrashort pulsed laser having a pulse width of 10-15 to 10-11 seconds. By this means, of the interface formed by the air gap (31) and the optical transparency sealing layer (30), the light emitted from the LED chip (20) is reflected at the part of the interface corresponding to the inner circumferential surface of the air gap (31).