Photonic Package Micro-Vents for Underfill Void Pressure Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Advanced photonic integrated circuits (PICs) face reliability issues due to macro underfill voids acting as pressure chambers, which can lead to damage during thermal exposure steps like surface mount during module assembly.
Innovation Solution
Incorporating micro vents that connect macro voids in the underfill to the edge of the underfill, allowing outgassed moisture to vent instead of being trapped, thereby preventing pressure buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If macro voids are created in the underfill to avoid underfill dispense over lasers, then laser reliability is improved, but pressure buildup occurs during thermal exposure causing damage to neighboring components
Solution Approach 1:
The patent introduces micro vents as intermediary channels that connect macro voids to the package exterior. These micro vents act as mediators that allow trapped gases and moisture to escape from the macro voids, preventing pressure buildup while maintaining the laser protection function. The micro vents are formed using sacrificial nanowire arrays that are removed after underfill dispensing, creating controlled pathways for pressure relief.
Solution Approach 2:
The patent utilizes a porous sacrificial material (nanowire array) that is temporarily embedded in the underfill. This porous structure serves as a template for creating vent channels. After the underfill cures, the sacrificial nanowires are removed through thermal decomposition or chemical etching, leaving behind porous vent pathways that allow pressure to escape from macro voids during subsequent thermal processing.
2Strength
If underfill is dispensed to support the die and interconnects, then mechanical strength is improved, but underfill must be avoided over lasers creating large voids that trap pressure
Solution Approach 1:
The patent segments the underfill structure by creating controlled void regions (macro voids) around laser areas while maintaining underfill in other regions for mechanical support. Additionally, micro vent channels are segmented throughout the underfill to provide multiple pressure relief pathways. This segmentation allows the underfill to simultaneously provide mechanical strength where needed and prevent pressure trapping where critical.
Solution Approach 2:
The patent incorporates sacrificial nanowire arrays into the underfill before dispensing and curing. This preliminary action creates a built-in pressure relief system that activates automatically during subsequent thermal processing. The nanowires are strategically placed to ensure pressure can escape from all potential trap regions before they cause damage, preventing the need for post-processing interventions.
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 presence of micro vents effectively mitigates the reliability risks associated with macro voids, ensuring that pressure is released and neighboring components are protected from damage during thermal exposure.
Implementation Method 1
the vent is fluidically coupled to the void and extends to an edge of the underfill... allowing outgassed moisture to vent
Implementation Method 2
outgassed moisture to vent instead of being trapped
Data Source
AI summary
Embodiments disclosed herein include electronic packages with vents to prevent pressure buildup below a die. In an embodiment, an electronic package comprises a package substrate and a die attached to the package substrate by interconnects. In an embodiment, an underfill is under the die and surrounds the interconnects. In an embodiment, a void is provided in the underfill, and a vent is in the underfill. In an embodiment, the vent is fluidically coupled to the void and extends to an edge of the underfill.