Flip-Chip Interconnect Layout for Faster Underfill Flow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As the density and size of flip-chip device interconnect layers increase, the dispersion of underfill material becomes challenging due to physical properties and manufacturing restraints, leading to limitations in the size of interconnect layers.
Innovation Solution
The electronic package design features an interconnect layer with solder bumps of varying cross-sectional areas, decreasing along the underfill flow direction, which creates a capillary action to enhance the flow rate and filling efficiency of underfill material, allowing for smaller pitches and larger, denser interconnect layers within manufacturability limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the density and size of C4 connection layers increase, then the number of connections and electrical circuitry complexity improve, but the dispersion of underfill material becomes increasingly difficult
Solution Approach 1:
The patent applies local quality by varying the cross-sectional area of individual solder bumps based on their position within the interconnect layer. Solder bumps near the underfill dispensation location have larger cross-sectional areas, while those farther away have progressively smaller areas. This localized variation in geometry creates position-dependent capillary forces that guide underfill material dispersion throughout the dense C4 connection array, resolving the contradiction between high connection density and underfill dispensability.
Solution Approach 2:
The patent implements parameter changes by systematically varying the cross-sectional area parameter of solder bumps across the interconnect layer. This geometric parameter variation creates a gradient in capillary pressure that drives underfill material flow through the connection layer. By changing the physical parameter (cross-sectional area) of the interconnect structures, the patent enables effective underfill dispersion in high-density configurations that would otherwise be manufacturing-challenging.
2Ease of manufacture
If the cross-sectional area of solder bumps is uniform, then manufacturing simplicity is maintained, but underfill material flow rate and filling efficiency are reduced
Solution Approach 1:
The patent applies local quality by varying the cross-sectional area of individual solder bumps based on their position within the interconnect layer. Solder bumps near the underfill dispensation location have larger cross-sectional areas, while those farther away have progressively smaller areas. This localized variation in geometry creates position-dependent capillary forces that guide underfill material dispersion throughout the dense C4 connection array, resolving the contradiction between high connection density and underfill dispensability.
Solution Approach 2:
The patent implements parameter changes by systematically varying the cross-sectional area parameter of solder bumps across the interconnect layer. This geometric parameter variation creates a gradient in capillary pressure that drives underfill material flow through the connection layer. By changing the physical parameter (cross-sectional area) of the interconnect structures, the patent enables effective underfill dispersion in high-density configurations that would otherwise be manufacturing-challenging.
3Strength
If larger cross-sectional areas are used for all solder bumps, then connection strength is improved, but underfill material cannot penetrate through the interconnect layer
Solution Approach 1:
The patent applies local quality by varying the cross-sectional area of individual solder bumps based on their position within the interconnect layer. Solder bumps near the underfill dispensation location have larger cross-sectional areas, while those farther away have progressively smaller areas. This localized variation in geometry creates position-dependent capillary forces that guide underfill material dispersion throughout the dense C4 connection array, resolving the contradiction between high connection density and underfill dispensability.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the interconnect layer with a gradient of cross-sectional areas before underfill dispensation. This pre-established geometric gradient creates inherent capillary pressure differences that automatically guide underfill flow through the entire layer during the dispensation process, eliminating the need for post-assembly adjustments or complex dispensing mechanisms.
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 design reduces the time required for underfill material to fill the interconnect layer, enabling the use of smaller pitches and supporting the assembly of larger electronic packages within existing manufacturing constraints.
Implementation Method 1
The interconnect layer includes a first subset of the plurality of solder bumps which may include a first cross-sectional area, and where the first subset is arranged along a first position at a first edge of the interconnect layer. The interconnect layer also includes a second subset of the plurality of solder bumps may include a second cross-sectional area, where the second subset is arranged at a second position of the interconnect layer, and a third subset of the plurality of solder bumps is arranged between the first position and the second position, where the third subset may include a plurality of cross-sectional areas.
Data Source
AI summary
A flip chip device and methods for fabrication are provided. An interconnect layer for a device include a plurality of solder bumps arranged within the interconnect layer. A first subset of the plurality of solder bumps has a first cross-sectional area, where the first subset is arranged along a first position at a first edge of the interconnect layer. A second subset of the plurality of solder bumps has a second cross-sectional area, where the second subset is arranged at a second position of the interconnect layer. A third subset of the plurality of solder bumps is arranged between the first position and the second position, where the third subset has a plurality of cross-sectional areas.