PCB Contact Pad Segmentation for Via Isolation
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Solution Overview
Problem
Conventional printed circuit boards (PCBs) face challenges in signal and voltage transfer due to limited surface area, requiring multiple layers and large contact pads that can cause via shorting, necessitating keep-out areas and complex manufacturing processes for blind or buried vias.
Innovation Solution
The PCB design incorporates coextensive electrical connectors and contact pad areas by etching voids into contact pads to ensure electrical isolation, allowing vias to be formed within the pad areas, reducing the number of layers needed and simplifying the trace and via layout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large contact pads are used to match the size of surface mounted contacts, then reliable electrical connection is achieved, but via shorting occurs when vias are formed through the substrate
Solution Approach 1:
The contact pad is segmented into multiple isolated regions by etching grooves through it. This segmentation allows vias to be formed in areas that would otherwise be part of the continuous contact pad, preventing via shorting while maintaining reliable electrical connections through the remaining pad segments.
Solution Approach 2:
Material is extracted from the contact pad by etching grooves through it, creating voids or channels. This removal of material prevents the formation of short circuits between vias while preserving the essential electrical connection function through the remaining pad structure.
2Reliability
If keep-out areas are defined around contact pads to prevent via shorting, then via shorting is avoided, but the number of vias that can be formed is reduced and layout complexity increases
Solution Approach 1:
Instead of creating keep-out areas that exclude vias from contact pad regions, the contact pad itself is segmented into multiple isolated regions. This allows vias to be positioned throughout the entire contact pad area without risk of shorting, eliminating the need for complex layout restrictions and keep-out zones.
3Quantity of substance
If multiple layers are used to provide sufficient surface area for signal and voltage transfer, then adequate electrical connection capacity is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of increasing the number of layers to provide sufficient electrical connection capacity, the invention utilizes the vertical dimension by etching grooves through the contact pad. This creates additional pathways and surface area within the same layer, allowing adequate electrical connection capacity without increasing layer complexity.
Data Source
AI summary
A printed circuit board is disclosed having coextensive electrical connectors and contact pad areas. Areas of the contact pads where the traces and/or vias are located may be etched away to ensure electrical isolation between the traces, vias and contact pads.