Hybrid PCB Redistribution Layer for Fine Pitch Interconnects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current printed circuit board (PCB) technology is limited in achieving fine feature pad pitches and conductive transmission line traces due to thermal-mechanical stress and requires expensive IC substrates for miniaturization, increasing package height and reducing component density.
Innovation Solution
A hybrid PCB system with a hybrid redistribution layer that balances and dissipates residual stress by combining wafer level packaging and IC substrate technologies within a single PCB, allowing direct attachment of electronic components with pad pitches less than 350 microns without an IC substrate or interposer, reducing the overall package form factor and increasing circuit density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If IC substrates are used for miniaturization, then pad pitch can be reduced below 350 microns, but package thickness increases and component density decreases
Solution Approach 1:
The patent merges the IC substrate redistribution layer functionality directly into the PCB structure by integrating a buffer layer with controlled CTE properties between the rigid PCB and the flexible electronic component. This integration eliminates the need for a separate IC substrate, reducing package thickness while enabling fine pad pitches through the hybrid material structure.
Solution Approach 2:
The patent employs composite materials by combining dielectric materials with specific coefficients of thermal expansion (CTE) in a buffer layer. This composite structure allows the PCB to accommodate thermal-mechanical stress from fine-pitch components without increasing package thickness, resolving the contradiction between precision and volume.
2Manufacturing precision
If IC substrates are used for miniaturization, then pad pitch can be reduced below 350 microns, but component density decreases
Solution Approach 1:
The patent combines the redistribution layer functionality with the PCB structure itself, eliminating the need for separate IC substrates. This merging enables direct mounting of fine-pitch electronic components onto the PCB, increasing component density while maintaining precision through the buffer layer's stress management capabilities.
3Ease of manufacture
If standard PCB materials are used, then manufacturing is simpler, but thermal-mechanical stress degrades interconnection reliability
Solution Approach 1:
The patent changes the physical parameters of the dielectric material by selecting materials with specific coefficients of thermal expansion (CTE) that match or bridge the CTE values of the PCB and electronic component. This parameter adjustment reduces thermal-mechanical stress at the interface, improving interconnection reliability while maintaining manufacturing simplicity through standard PCB fabrication processes.
Solution Approach 2:
The patent uses composite dielectric materials with tailored CTE properties in the buffer layer to mediate thermal-mechanical stress between the rigid PCB and flexible component. This composite approach maintains manufacturing simplicity while significantly improving interconnection reliability through stress distribution.
4Reliability
If hybrid redistribution layer is implemented, then interconnect reliability improves, but manufacturing process becomes more complex
Solution Approach 1:
The patent segments the PCB structure into distinct functional layers: a standard PCB core, a buffer layer with specialized CTE properties, and the electronic component. This segmentation allows each layer to be optimized independently and facilitates manufacturing by enabling the use of standard PCB fabrication processes for the majority of the structure, with only the buffer layer requiring specialized material selection.
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
The hybrid PCB system enhances interconnect reliability and assembly efficiency, reduces component-level interconnects, and miniaturizes line width and spacing, addressing thermal-mechanical stress while maintaining signal integrity and reducing costs.
Implementation Method 1
The attachment between the electronic component and the PCB is subject to many types of stress, any one or combination of which may lead to degradation of the interconnection and eventual failure. One such stress is thermal-mechanical stress, also referred to as residual stress, due to thermal mismatch between the various materials within the PCB
Data Source
AI summary
A hybrid PCB system has a hybrid redistribution layer that redistributes a large pad-to-pad pitch to a smaller, finer pad-to-pad pitch and applies hybrid materials to balance the thermal-mechanical stress. The hybrid PCB system combines wafer level packaging, IC substrate and high density PCB technologies within a single hybrid PCB. The hybrid PCB system addresses the opportunity for interconnect reliability, design and assembly of a electronic components with pad pitches less than 400 microns directly to a PCB without need of an IC substrate or interposer.