Composite PCB Layout With Embedded HDI Modules for Signal Integrity
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Solution Overview
Problem
Type-III printed circuit boards (PCBs) experience signal degradation due to impedance discontinuities and reflections from un-terminated transmission lines, which can reduce memory performance, while higher-cost Type-IV PCBs with HDI technologies offer better signal integrity but come with increased costs and assembly challenges.
Innovation Solution
A composite PCB design combining a Type-III motherboard with embedded Type-IV translator modules, utilizing micro-via technology and zero-ohm resistors for improved signal integrity and reduced z-height, allowing for high-density interconnects and power delivery without open-ended PTH stubs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Type-III PCB with PTH vias is used, then cost is reduced, but signal integrity deteriorates due to impedance discontinuities and reflections from unused stubs
Solution Approach 1:
The PCB is segmented into different via types (PTH vias for power/ground, blind vias for signal routing) and functional zones (memory I/O region with HDI, other regions with standard PTH). This segmentation allows signal-critical paths to use stubless blind vias while non-critical paths use simpler PTH vias, resolving the contradiction between cost and signal integrity.
Solution Approach 2:
Different via technologies are applied locally based on functional requirements: blind vias are used in the memory I/O region where signal integrity is critical, while PTH vias are used in other regions where cost is more important. This local differentiation resolves the contradiction by applying high-performance features only where necessary.
2Reliability
If Type-IV PCB with HDI and blind vias is used, then signal integrity is improved by eliminating PTH stubs, but manufacturing cost increases
Solution Approach 1:
Instead of implementing HDI blind via technology across the entire PCB (excessive action), the patent applies it partially only to the memory I/O region where signal integrity is most critical. This partial application achieves the necessary signal quality improvement while avoiding the excessive cost increase of full-PCB HDI implementation.
3Reliability
If translator module board is used, then memory signal routing is improved, but device complexity and assembly challenges increase
Solution Approach 1:
The patent merges the translator module functionality directly into the main PCB by creating a composite structure with integrated blind via regions, rather than using a separate translator module board. This integration eliminates the need for additional interconnects and reduces assembly complexity while maintaining the signal routing benefits.
Solution Approach 2:
The composite PCB structure serves multiple functions simultaneously: it provides both standard PTH via connections for cost-effective routing and blind via connections for high-speed memory signals, all within a single board architecture. This multi-functionality eliminates the need for separate translator modules while achieving both cost and performance goals.
Data Source
AI summary
The present disclosure is directed to a printed circuit board having a composite upper surface with a first section of a first-type of printed circuit board and a second section of a second-type of printed circuit board, for which the first section of the first-type of printed circuit board and the second section of the second-type of printed circuit board are coupled, respectively, to at least one device that is configured to abridge the first and second sections of the composite upper surface. In an aspect, the second-type of printed circuit board is configured to be embedded in the first-type of printed circuit board and the first-type of printed circuit board is configured to receive the second-type of printed circuit board.