Wall Pillar Interconnect Assembly Without Underfill
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Solution Overview
Problem
There is a need to improve the performance of integrated devices and packages while maintaining a small form factor, and existing technologies face challenges in achieving effective mechanical coupling between passive devices and substrates without the need for underfill materials.
Innovation Solution
The use of wall pillar interconnects and wall under bump metallization interconnects provides improved mechanical coupling between passive devices and substrates, eliminating the need for underfill materials by enhancing the vertical overlap and overlap dimensions of interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional interconnect structures are used, then the package can be assembled with standard materials, but mechanical coupling between passive devices and substrates is insufficient requiring underfill materials
Solution Approach 1:
The interconnect structure transitions from a planar two-dimensional configuration to a three-dimensional structure with vertical pillars extending through the substrate. This dimensional change creates overlapping regions where passive devices can be mechanically coupled to the substrate through the pillars, eliminating the need for underfill materials while strengthening the mechanical bond.
Solution Approach 2:
The wall pillar interconnects are formed by nesting conductive materials within recesses or trenches in the substrate. The passive devices are then positioned to overlap with these nested pillar structures, creating a mechanically coupled assembly where the pillars are embedded within the device substrate, similar to nested dolls.
2Reliability
If underfill materials are used to ensure mechanical coupling, then assembly reliability is improved, but the form factor increases and performance is compromised
Solution Approach 1:
The underfill material, which is typically used to provide mechanical coupling and reliability in packaged devices, is completely removed from the design. Instead, the mechanical coupling function is achieved through the wall pillar interconnect structure itself, which provides direct structural support and bonding between the passive device and substrate without requiring additional underfill materials.
3Productivity
If the number of interconnects is increased to improve performance, then electrical function is enhanced, but the form factor increases
Solution Approach 1:
The interconnect design utilizes the vertical dimension by extending pillars through the substrate thickness, allowing multiple interconnect functions to be achieved within a compact lateral footprint. The overlapping configuration enables electrical pathways to be established in the vertical direction rather than requiring extensive lateral spreading, thus improving performance while maintaining a small form factor.
Data Source
AI summary
A package comprising a substrate and a passive device coupled to the substrate through a plurality of solder interconnects. The substrate comprises at least one dielectric layer; and a plurality of interconnects. The passive device comprises a die substrate; a plurality of under bump metallization interconnects; and a plurality of pillar interconnects coupled to the plurality of under bump metallization interconnects, wherein at least one pillar interconnect comprises a wall pillar interconnect.