Optoelectronic Packaging Assemblies Underfill Dam Alignment
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Solution Overview
Problem
Optoelectronic packaging assemblies face challenges in thermal management, materials compatibility, optical alignment, and cost effectiveness, particularly in high-bandwidth applications such as data centers and server boards, where traditional packaging methods struggle to meet size, integration, and performance demands.
Innovation Solution
The development of optoelectronic packaging assemblies that include a thinned driver IC chip directly bonded to a laser chip with thermal management components and underfill dams to prevent underfill flow into optical overhang areas, using thermocompression or epoxy bonding for electrical connections, and passivation layers to manage solder and underfill layers, enabling efficient thermal management and alignment while reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional packaging methods are used, then manufacturing simplicity is maintained, but thermal management and integration density cannot meet high-bandwidth performance demands
Solution Approach 1:
The patent combines multiple functions into integrated structures: the driver IC chip is directly bonded to the laser chip, thermal management components are integrated with the laser chip assembly, and electrical interconnects are formed through direct bonding rather than separate packaging steps. This merging enables high bandwidth performance while managing the complexity through functional integration.
Solution Approach 2:
The patent employs nested packaging where the driver IC chip is positioned and bonded directly onto the laser chip, which itself is mounted on the packaging substrate. Multiple layers of functionality are nested within compact vertical space, achieving high interconnect density and integration efficiency without excessive horizontal expansion.
2Volume of moving object
If chip size is reduced for smaller form factors, then packaging area is reduced, but thermal management and alignment precision become more challenging
Solution Approach 1:
The patent transitions from two-dimensional planar packaging to three-dimensional vertical stacking. The driver IC chip is bonded directly to the top surface of the laser chip, utilizing the vertical dimension to achieve compact form factor while maintaining adequate separation for thermal management and optical alignment through precise z-height control of bonding layers.
Solution Approach 2:
The patent applies different material properties and structural characteristics to specific regions: the underfill material provides mechanical support and thermal pathways in regions away from optical paths, while the optical overhang area maintains precise clearance for light propagation. This localized differentiation enables small form factor with maintained alignment precision.
3Productivity
If high interconnect density is achieved through direct bonding, then integration efficiency improves, but thermal management challenges increase
Solution Approach 1:
The patent introduces underfill material as an intermediary substance between the driver IC chip and packaging substrate. This underfill serves multiple functions: it provides mechanical support for the bonded chips, creates thermal pathways to conduct heat away from the high-density interconnect regions, and maintains precise spacing for optical alignment while allowing thermal expansion.
Solution Approach 2:
The patent employs composite material structures combining different thermal and optical properties: the laser chip itself is a composite of semiconductor materials with specific thermal conductivity, the underfill is a composite polymer matrix with thermal pathways, and thermal management components are integrated with these composite structures to conduct heat away from high-density interconnect regions.
4Ease of manufacture
If underfill is allowed to flow freely during packaging, then manufacturing simplicity is maintained, but optical alignment is compromised due to underfill intrusion into optical overhang areas
Solution Approach 1:
The patent creates preliminary protective structures (such as dams or barriers) around the optical overhang areas before applying the underfill material. These pre-formed barriers prevent underfill intrusion into critical optical regions while allowing the underfill to freely fill the remaining packaging space, thus maintaining manufacturing simplicity without compromising optical alignment precision.
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 small form factors, improved reliability, and cost-effectiveness for high-performance optical data transfer applications by enhancing thermal management and alignment while maintaining high interconnect density and integration efficiency.
Implementation Method 1
a thermal management component in thermal contact with a surface of the laser chip
Implementation Method 2
using thermocompression or epoxy bonding for electrical connections
Data Source
AI summary
Optoelectronic packaging assemblies are provided that are useful for optical data, transfer In high performance computing applications, board to board in data centers, memory to CPU, switch/FPGA (field programmable gate array) for chip to chip interconnects, and memory extension. The packaging assemblies provide fine pitch flip chip interconnects and chip stacking assemblies with good thermo-mechanical reliability. Underfill dams and optical overhang regions and are provided for optical interconnection.