Integrated PIC Heater Structure for Solder-Reflow Optical Alignment

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Solution Overview

Problem

In silicon photonic technology, traditional epoxy-based alignment methods are inadequate for maintaining light coupling efficiency due to poor thermal conductivity, moisture sensitivity, and inability to adjust for misalignment, leading to reduced device lifespan and increased manufacturing costs.

Innovation Solution

Integration of a photonic integrated circuit (PIC) with a grating coupler and an optical bench, using a layer of solder and localized heating by an integrated heater to secure and realign the optical bench with the PIC, allowing for precise alignment and heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If epoxy-based alignment methods are used to attach optical components, then alignment is achieved, but thermal conductivity is poor and moisture sensitivity increases

Engineering Contradiction:

Improvealignment precisionVSAvoidmoisture sensitivity

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the material parameter from epoxy to solder, fundamentally altering thermal conductivity and moisture resistance properties while maintaining alignment functionality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/chemical bonding system (epoxy) with a metallurgical bonding system (solder), leveraging phase transition and thermal conduction properties to achieve both alignment and environmental stability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If epoxy-based alignment methods are used, then alignment is achieved, but the ability to adjust for misalignment is lost

Engineering Contradiction:

Improvealignment precisionVSAvoidadjustability

Core Design Contradiction:

Measurement precisionVSEase of repair

Solution Approach 1:

The patent introduces a dynamic heating element that allows the solder to transition between solid (fixed alignment) and liquid (adjustable alignment) states, enabling both precise alignment and subsequent adjustment capability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent performs preliminary alignment while the solder is in liquid state before it solidifies, allowing adjustment opportunities before final fixation occurs

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If traditional attachment methods are used, then manufacturing is simple, but device lifespan is reduced

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoiddevice lifespan

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The patent uses a composite attachment system combining solder material with integrated heating elements, creating a multi-functional attachment structure that provides both mechanical bonding and thermal management for extended device life

Inventive Principle:

Principle #40Composite materials

4Device complexity

If epoxy-based methods are used for heat dissipation, then structure is simple, but thermal conductivity is insufficient

Engineering Contradiction:

Improvestructural complexityVSAvoidthermal conductivity

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent makes the attachment layer (solder) serve multiple functions: mechanical bonding, thermal conduction pathway, and moisture barrier, eliminating the need for separate thermal management components

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent introduces an integrated heater as an intermediary element between the laser diode and heat sink, creating an efficient thermal conduction pathway that actively manages heat flow

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution enhances light coupling efficiency, extends device lifespan, and improves manufacturing yield by enabling re-adjustment of alignment and heat management, overcoming the limitations of epoxy-based methods.

Implementation Method 1

heating by the integrated heater to melt and reflow the solder

Methodology Applied

Scientific EffectResistive heating: Joule Heating

Implementation Method 2

The layer of solder is in thermal communication with the integrated heater

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3857278B1Integrated heater structures in a photonic integrated circuit for solder attachment applications

Publication Date: 2024.01.03 GOOGLE LLC

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AI summary

An apparatus (100) including a photonic integrated circuit (PIC) (120) coupled to an optical bench (160) is disclosed. The PIC (120) includes at least one grating coupler (130) disposed thereon and the optical bench (160) includes an optical system (180) disposed thereon. The apparatus (100) also includes an integrated heater (140) at an upper surface of the PIC (120) under the optical bench (160) or at a bottom surface of the optical bench (160) over the PIC (120). The apparatus (100) also includes a layer of solder (150) disposed between the PIC (120) and the optical bench (160) for coupling the bottom surface of the optical bench (160) to the PIC (120). In some implementations, the layer of solder (150) is in thermal communication with the integrated heater (140).