Package Substrate Build-Up Layers for Planarity and Fine Interconnects
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Solution Overview
Problem
Conventional package substrates face limitations in achieving high-density interconnect geometries and planarity due to the properties of pre-impregnated composite fibers and Ajinomoto Build-up Film, which restrict device miniaturization and lead to thermal expansion issues causing substrate damage.
Innovation Solution
The use of multiple dielectric materials with different compositions around a core with electrically conductive vias, where pre-impregnated composite fibers provide rigidity and Ajinomoto Build-up Film enables finer interconnect geometries, allowing for simultaneous support of dense interconnects and increased substrate planarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pre-impregnated composite fibers are used for build-up layers, then the rigidity of the package substrate is increased, but the ability to support high density wiring schemes is limited
Solution Approach 1:
The build-up structure is segmented into multiple layers with different dielectric materials. Pre-impregnated composite fibers are used in outer layers to provide rigidity, while ABF is used in inner layers to enable high-density interconnects. This segmentation allows each layer to optimize for its specific function without compromising the other.
Solution Approach 2:
Different regions of the build-up structure use different dielectric materials based on local requirements. Areas requiring high interconnect density use ABF, while areas requiring structural support use pre-impregnated composite fibers. This local quality approach ensures optimal performance in each region.
2Manufacturing precision
If Ajinomoto Build-up Film is used for build-up layers, then high density wiring schemes are supported, but the coefficient of thermal expansion increases causing bowing and cracking
Solution Approach 1:
The build-up structure is divided into multiple layers with different dielectric materials. ABF is used in inner layers where high-density interconnects are required, while pre-impregnated composite fibers with lower thermal expansion are used in outer layers to provide thermal stability and reduce overall thermal expansion of the substrate.
Solution Approach 2:
The build-up structure uses a composite of different dielectric materials (ABF and pre-impregnated composite fibers) to combine the advantages of each material. ABF provides excellent interconnect formation capabilities, while pre-impregnated composite fibers provide thermal stability and structural support, creating a composite structure that mitigates the thermal expansion issues of ABF.
3Ease of manufacture
If a single dielectric material is used throughout the build-up layers, then manufacturing is simplified, but the ability to achieve both fine interconnect geometries and package planarity is compromised
Solution Approach 1:
The build-up structure is segmented into multiple layers with different dielectric materials optimized for specific functions. This segmentation enables simultaneous achievement of fine interconnect geometries and package planarity while maintaining reasonable manufacturing complexity through standardized layering processes.
Solution Approach 2:
The multi-layer dielectric structure serves multiple functions simultaneously: it provides electrical insulation, enables high-density interconnects, maintains package planarity, and provides structural support. This multi-functionality is achieved through the coordinated use of different dielectric materials in different layers, each contributing specific properties to the overall system.
Data Source
AI summary
Embodiments of the invention generally relate to package substrates for integrated circuits. The package substrates each include a core having electrically conductive vias therethrough. Build-up layers formed from dielectric materials having different compositions are disposed around the core and include interconnects formed therein for facilitating electrical connections between integrated circuits coupled to the package substrate. The dielectric materials are selected to allow finer interconnect geometries where desired, and to increase the rigidity, and thus planarity, of the package substrate. Exemplary dielectric materials include pre-impregnated composite fibers for increasing the rigidity of a package substrate, and Ajinomoto Build-up Film for allowing the formation finer interconnect geometries.