Polymer Core Interconnects for IC Package Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As integrated circuit (IC) dies shrink, the pitch between first-level interconnect structures decreases, leading to process and reliability risks such as solder bridging, voids, and delamination due to contraction and inter-metallic compound reactions during reflow, which current technologies struggle to mitigate effectively.
Innovation Solution
The implementation of interconnect structures with a polymer core, where the polymer core is composed of hyper-branched polymers and coated with electrically conductive materials, allowing for controlled collapse and reduced stress during thermal processes, thereby preventing defects like solder bridging and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pitch between first-level interconnect structures is reduced to accommodate smaller IC dies, then the integration density is improved, but solder bridging and void defects occur due to contraction and inter-metallic compound reactions during reflow
Solution Approach 1:
The interconnect structure is segmented into multiple functional layers: a polymer core providing structural support, an intermediate metal layer (e.g., nickel) as a diffusion barrier, and an outer solder layer. This segmentation prevents unwanted interactions between solder and substrate metals, eliminating inter-metallic compound formation that causes voids and bridging at tight pitches
Solution Approach 2:
The invention uses composite material structures combining polymer and metal layers. The polymer core (e.g., epoxy or polyimide) provides mechanical support and stress relief, while the metal layers provide electrical conductivity and solderability. This composite structure maintains reliability at reduced pitches by decoupling the mechanical and electrical functions
2Productivity
If bulk solder interconnect structures are used with tighter pitch, then the interconnect density is improved, but solder wicking and void formation occur due to contraction during reflow
Solution Approach 1:
The invention changes the physical parameters of the interconnect structure by introducing a polymer core with specific mechanical properties (modulus, thermal expansion coefficient) that differ from traditional bulk solder structures. This allows control over solder collapse behavior during reflow, preventing excessive wicking while maintaining precise height control through the polymer core's dimensional stability
Solution Approach 2:
The polymer core acts as an intermediary between the substrate and the solder layer, controlling the collapse behavior of the solder during reflow. The intermediate metal layer (nickel) serves as a mediator preventing direct contact between solder and substrate metals, eliminating the root cause of wicking and void formation
3Length of stationary object
If through-mold interconnects are used to reduce package assembly height, then the overall package height is reduced, but solder collapse and ball merging defects occur
Solution Approach 1:
The polymer core's mechanical properties (modulus, diameter) are specifically engineered to control solder collapse during reflow. By adjusting these parameters, the structure achieves controlled collapse that prevents ball merging while still reducing overall height, maintaining solder joint integrity in through-mold interconnect applications
Solution Approach 2:
The polymer core functions as a flexible structural element that can deform controllably during reflow. This flexibility allows the interconnect to adapt to thermal expansion differences and control solder flow, preventing defects while achieving the height reduction needed for through-mold configurations
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 solution enables precise control of solder height and collapse, reducing defects and stress in IC package assemblies, improving reliability and flexibility of interconnects, and facilitating tighter pitch assemblies without solder bridging.
Implementation Method 1
the polymer core is configured to control a collapse of the electrically conductive material during heating of the electrically conductive material to define a gap distance between the first die and the second die
Implementation Method 2
heating of the electrically conductive material to define a gap distance between the first die and the second die
Data Source
AI summary
Embodiments of the present disclosure are directed towards techniques and configurations of interconnect structures having a polymer core in integrated circuit (IC) package assemblies. In one embodiment, an apparatus includes a first die having a plurality of transistor devices disposed on an active side of the first die and a plurality of interconnect structures electrically coupled with the first die, wherein individual interconnect structures of the plurality of interconnect structures have a polymer core, and an electrically conductive material disposed on the polymer core, the electrically conductive material being configured to route electrical signals between the transistor devices of the first die and a second die. Other embodiments may be described and/or claimed.