Secondary-Side Heatsink Layout for Dense Optical Modules

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Solution Overview

Problem

The challenge in thermal management of high-density electrical and optical hardware modules is exacerbated by the limited space on the secondary side of Printed Circuit Board Assemblies (PCBAs), where components such as Ball Grid Array (BGA) components and pluggable optical modules require effective cooling without the luxury of ample vertical space.

Innovation Solution

The implementation of a secondary side heatsink system that includes a floating heatsink and a height-adjustable coin-style heatsink, which can be positioned to effectively cool components on both the secondary and primary sides of the PCBA, utilizing compact wave springs and adjustable set screws to optimize thermal management within the constrained space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If components are mounted on the secondary side of the PCBA to increase density, then component placement flexibility is improved, but thermal management becomes more difficult due to limited space for heatsinks

Engineering Contradiction:

Improvecomponent placement flexibilityVSAvoidthermal management capability

Core Design Contradiction:

Adaptability or versatilityVSTemperature

Solution Approach 1:

The patent utilizes the vertical dimension by extending the heatsink from the secondary side through the PCBA to contact components on the primary side. This three-dimensional thermal management approach allows effective heat dissipation from high-power components while maintaining the space-constrained secondary side layout for component placement flexibility.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The thermal management system is segmented into two parts: a secondary side heatsink structure that provides thermal contact from the constrained side, and a primary side contact surface that interfaces with high-power components. This segmentation allows each side to be optimized independently for its specific function.

Inventive Principle:

Principle #1Segmentation

2Temperature

If a secondary side heatsink is added to cool components on the secondary side, then thermal management is improved, but the device complexity increases due to additional mounting mechanisms

Engineering Contradiction:

Improvethermal managementVSAvoidmounting mechanism complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent combines the secondary side heatsink mounting structure with the existing PCBA mechanical framework. The heatsink is integrated into the module housing and utilizes the PCBA stack-up structure, merging thermal management functionality with the existing mechanical design rather than adding completely separate mounting mechanisms.

Inventive Principle:

Principle #5Merging (Combining)

3Temperature

If the secondary side heatsink extends through the PCBA to cool primary side components, then thermal management effectiveness is improved, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvethermal management effectivenessVSAvoidheatsink alignment precision

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The patent employs adjustable height mechanisms (such as adjustable standoffs or compliant mounting features) that allow the heatsink contact surface to be positioned at the optimal height for thermal contact. This adjustability compensates for manufacturing tolerances in the PCBA thickness and component placement, maintaining effective thermal management without requiring extremely tight manufacturing precision.

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

This solution enables efficient thermal management of high-power components on the secondary side of PCBAs, maintaining component temperatures within operational limits while minimizing space occupancy on the primary side, thus enhancing the thermal performance and density of hardware modules.

Implementation Method 1

The floating heatsink can be connected through the printed circuit board assembly to the primary side via a compact wave spring

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a secondary side heatsink located on and extending from the secondary side, wherein the secondary side heatsink is disposed to one of i) an electrical and/or optical component disposed on the secondary side

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

The secondary side heatsink can be a coin-style heatsink that extends through the printed circuit board assembly to the optical component disposed on the primary side

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS12288954B2Secondary side heatsink techniques for optical and electrical modules

Publication Date: 2025.04.29 CIENA CORP

AI summary

A module for use in a hardware platform for networking, computing, and/or storage includes a printed circuit board assembly having a primary side and a secondary side, wherein the primary side includes more physical space, in a vertical direction extending out from the printed circuit board assembly, than the secondary side; electrical and/or optical components disposed on the primary side of the printed circuit board assembly; and a secondary side heatsink located on and extending from the secondary side, wherein the secondary side heatsink is disposed to one of i) an electrical and/or optical component disposed on the secondary side, and ii) an optical component disposed on the primary side, for thermal management.