Microelectronic Package Substrate Vents for Encapsulant Flow
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Solution Overview
Problem
In microelectronic packages with multiple chips in a quad face-down orientation, the encapsulant material often fails to completely fill openings due to air entrapment, leading to voids when flowing in a single direction, which is undesirable for manufacturing efficiency and package reliability.
Innovation Solution
The design includes elongated openings in the substrate with specific alignment and vent configurations that allow encapsulant material to flow in a transverse direction, ensuring complete filling and minimizing air entrapment by providing pathways for air to escape, such as bond channel windows and vents, which are in fluid communication with the environment during encapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If encapsulant material is flowed in a single direction over the substrate, then the manufacturing process is simple, but the openings may not be completely filled due to air entrapment
Solution Approach 1:
The encapsulation process is segmented into multiple directional flow stages. The molding compound is first flowed in a first direction to fill openings with contacts, then in a second direction transverse to the first to fill bond channel windows. This segmentation allows air to escape progressively rather than being trapped, ensuring complete filling while maintaining process simplicity.
Solution Approach 2:
The invention introduces a transverse flow direction (second direction) that is perpendicular to the initial flow direction (first direction). This dimensional change in material flow allows encapsulant to access and fill different regions of the package effectively, ensuring complete filling of both openings and bond channel windows without complex tooling.
2Productivity
If openings are configured for quad face-down chip orientation, then multiple chips can be mounted efficiently, but air entrapment occurs during encapsulation
Solution Approach 1:
The invention creates different local flow conditions for different regions of the package. Openings with contacts are filled primarily in the first direction, while bond channel windows are filled in the transverse second direction. This localized quality control ensures that each region is optimally filled according to its specific geometric and functional requirements, preventing air entrapment while maintaining high productivity for quad face-down configurations.
3Productivity
If encapsulant material flows quickly to maintain productivity, then manufacturing speed is high, but air pockets form in openings
Solution Approach 1:
The invention performs preliminary filling action in the first direction before the transverse second direction flow. This preliminary action allows air to be progressively displaced and escape through designated pathways, preventing air pocket formation. The sequence of operations is built into the process design, allowing high speed without sacrificing filling completeness.
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 configuration ensures that encapsulant material can flow into the openings from both ends, preventing air pockets and voids, thereby enhancing the filling process and improving the reliability and efficiency of microelectronic package manufacturing.
Implementation Method 1
the material is typically flowed from a molding tool 30 in a single direction X over the top surface or attachment layer 18 side of the substrate 16
Data Source
AI summary
A microelectronic assembly may include a substrate having an opening extending between first and second oppositely facing surfaces of the substrate, the opening elongated in a first direction; and at least one microelectronic element having a front face facing and attached to the first surface of the substrate and a plurality of contacts at the front face overlying the opening, the microelectronic element having first and second opposite peripheral edges extending away from the front face. The first peripheral edge extends beyond, or is aligned in the first direction with, an inner edge of the opening, and the opening extends beyond the second peripheral edge.