Reflow-Compatible Optical I/O Adapter for SiP Assembly

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Solution Overview

Problem

The assembly of silicon photonic (SiP) chips with external optical fibers is challenging due to micron-scale alignment requirements, mechanical support issues, and contamination risks, with current techniques prone to damaging fragile components and lacking reflow compatibility for high-temperature soldering processes.

Innovation Solution

A reflow-compatible assembly adapter with coarse-alignment structures, a clamp, and dust protection features, made from materials like liquid-crystal polymer (LCP) or metal, which encloses a packaged optoelectronic module (POeM) and includes a mechanical transfer (MT) ferrule cavity to guide optical fibers, ensuring robust mechanical support and thermal dissipation during assembly and operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a passive optical connector is used to connect optical components on SiP chip to external optical fiber, then optical signal transmission is enabled, but the assembly process becomes challenging due to required micron-scale alignment and handling of optical fibers

Engineering Contradiction:

Improveoptical signal transmissionVSAvoidassembly process

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent introduces an assembly adapter as an intermediary component that mediates between the optical connector and the SiP chip. The adapter provides coarse alignment features and mechanical support, making the assembly process easier while maintaining optical signal transmission reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent divides the assembly into separate functional components: the optical connector, the assembly adapter with coarse alignment features, and the SiP chip. This segmentation allows each component to be optimized independently and simplifies the overall assembly process.

Inventive Principle:

Principle #1Segmentation

2Strength

If clamping force is applied to secure MT ferrule to optical connector, then mechanical connection is achieved, but critical optical coupling interfaces and fragile components can be damaged

Engineering Contradiction:

Improvemechanical connectionVSAvoiddamage to optical interfaces

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent incorporates protective features in the assembly adapter that cushion and distribute the clamping force before it reaches the fragile optical interfaces. The adapter's structural design prevents concentration of stress on critical coupling areas.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The assembly adapter uses flexible or compliant structural elements that can deform under clamping force, absorbing the stress and preventing damage to rigid optical interfaces and fragile components.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If fine-precision mating structures are used to guarantee low-loss optical coupling, then optical performance is improved, but the structures are prone to damage after multiple assembly insertions

Engineering Contradiction:

Improveoptical coupling performanceVSAvoiddurability of mating structures

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent implements coarse alignment structures in the assembly adapter that perform the preliminary alignment function before the fine-precision mating structures engage. This preliminary action prevents misalignment stress and wear on the delicate fine-precision features during insertion.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The alignment function is segmented into two stages: coarse alignment provided by the adapter's mechanical features, and fine alignment provided by the precision mating structures. This segmentation protects the fine structures from damage by handling the rough alignment separately.

Inventive Principle:

Principle #1Segmentation

4Adaptability or versatility

If MT ferrule is assembled last to enclose optical fibers, then flexibility in assembly is maintained, but the interface of passive optical connector remains exposed to contamination

Engineering Contradiction:

Improveassembly flexibilityVSAvoidcontamination of optical facets

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The assembly adapter is designed with nested protective features where dust caps or protective covers can be inserted into the adapter housing to protect the optical connector interface. This nested structure maintains assembly flexibility while preventing contamination when the ferrule is not installed.

Inventive Principle:

Principle #7Nested doll (Nesting)

5Reliability

If advanced socket technologies are used to connect optoelectronic modules to PCB, then reliability is improved, but footprint size increases due to low I/O density

Engineering Contradiction:

Improveconnection reliabilityVSAvoidfootprint size

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent changes the connection technology parameter from advanced sockets to solder I/Os, which have higher I/O density and smaller footprint. The assembly adapter is designed to be compatible with soldering processes, enabling this parameter change while maintaining reliability through proper thermal and mechanical design.

Inventive Principle:

Principle #35Parameter changes

6Area of stationary object

If solder I/Os are used instead of advanced sockets, then footprint size is reduced, but reflow compatibility becomes challenging for optical components

Engineering Contradiction:

Improvefootprint sizeVSAvoidreflow compatibility

Core Design Contradiction:

Area of stationary objectVSAdaptability or versatility

Solution Approach 1:

The patent changes the material parameter of the assembly adapter to use reflow-compatible materials that can withstand the high temperatures of solder reflow processes. This enables the use of solder I/Os with smaller footprint while maintaining compatibility with standard PCB assembly processes.

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 provides a seamless assembly process with enhanced mechanical protection, reduced risk of contamination, and improved thermal dissipation, enabling durable and efficient optical connectivity compatible with reflow soldering processes.

Implementation Method 1

ensuring the assembly process compatibility with reflow solder I/Os... providing adequate thermal dissipation for ICs (electronic and optoelectronic)

Methodology Applied

Scientific EffectThermal dissipation: Conduction (thermal)

Data Source

PatentUS10591689B2Reflow-compatible optical I/O assembly adapter

Publication Date: 2020.03.17 ORACLE INT CORP

AI summary

The disclosed embodiments provide an apparatus for connecting one or more optical fibers to an optoelectronic system. This apparatus includes a packaged optoelectronic module (POeM) comprising an optical connector, a silicon photonic (SiP) chip, an integrated circuit (IC) chip, at least one laser chip and a package substrate. The apparatus also includes an assembly adapter enclosing the POeM, wherein the assembly adapter includes a mechanical transfer (MT) ferrule cavity, which includes one or more coarse-alignment structures to guide an MT ferrule enclosing at least one optical fiber during assembly of the apparatus. The assembly adapter is comprised of a solder-reflow-compatible material to facilitate bonding the assembly adapter to a circuit board.