Interposer Dam Structure for Underfill Control in IPD Integration
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Solution Overview
Problem
In semiconductor package assemblies, the presence of underfill material can degrade the performance of solder portions due to overlap, rendering them inoperable, and existing fabrication processes face challenges in integrating integrated passive devices without compromising the integrity of the assembly.
Innovation Solution
The introduction of a dam structure in the interposer to constrain the spatial extent of the underfill material, preventing it from overlapping with adjacent bonding structures, combined with a method of forming the dam alongside redistribution interconnect layers with minimal modifications to existing fabrication processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If underfill material is applied without constraints, then bonding structures are protected from thermal stress, but underfill material overlaps with adjacent bonding structures degrading performance
Solution Approach 1:
A dam structure is introduced as an intermediary element between the underfill material and bonding structures. The dam acts as a physical barrier that mediates the interaction, allowing thermal stress protection while preventing material overlap. The dam includes a first portion extending above the interposer surface and a second portion embedded below the surface, creating a containment structure that guides underfill material placement.
Solution Approach 2:
The dam structure is formed in the interposer before the underfill material is applied. This preliminary action establishes the spatial boundaries that will constrain the underfill material during subsequent bonding operations, ensuring proper placement accuracy before the actual bonding process occurs.
2Manufacturing precision
If a continuous dam structure is used to constrain underfill material, then placement precision is improved, but thermal stress concentrations increase
Solution Approach 1:
The dam structure is divided into multiple disconnected segments rather than forming a continuous barrier. Each segment independently constrains underfill material in specific regions while the gaps between segments allow stress relief. This segmentation maintains placement precision through localized constraint while reducing overall thermal stress concentrations by breaking the continuous stress path.
Data Source
AI summary
An embodiment semiconductor package assembly may include an interposer, an integrated passive device electrically coupled to a first side of the interposer, an underfill material portion formed between the integrated passive device and the first side of the interposer, and a dam protruding from the first side of the interposer and configured to constrain a spatial extent of the underfill material portion. The dam may include a first portion extending above a surface of the first side of the interposer and a second portion embedded below the surface of the first side of the interposer. The dam may be formed in a dielectric layer that also includes a component of a redistribution interconnect structure. The dam may further be electrically isolated from the redistribution interconnect structure and may be configured to form a connected or disconnected boundary of a two-dimensional region of the first side of the interposer.