Via Trace Connection for High Routing Density Circuit Boards
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Solution Overview
Problem
Conventional circuit board designs face challenges in increasing routing density due to the limitations of via and via land sizes, which restrict the placement of additional traces and can lead to device failure from excessive current densities, while attempts to shrink via sizes are hindered by design rules and the need for larger via hole sizes.
Innovation Solution
The method involves forming interconnect layers with conductor traces that do not include via lands, allowing vias to be positioned directly on these traces, enabling the nesting of multiple traces between via segments without increasing package substrate size, thus enhancing routing density without exceeding current density thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If via sizes are shrunk to accommodate additional trace routing, then routing density is improved, but current density increases and can cause device failure
Solution Approach 1:
The via structure is segmented into two distinct components: a reduced-size via hole for routing and a separate via land pad for current distribution. This segmentation allows the via hole to be small enough for high routing density while the via land provides sufficient area for current dissipation, resolving the contradiction between routing density and device reliability.
Solution Approach 2:
The via land acts as an intermediary element between the via hole and the trace routing. It serves as a current distribution node that decouples the via hole size from the current carrying requirements, allowing small via holes to be used without compromising current handling capability.
2Reliability
If via hole sizes are increased to avoid current density issues, then device reliability is improved, but routing density decreases due to larger via occupancy
Solution Approach 1:
By segmenting the via structure into a small via hole and a separate via land, the current distribution function is separated from the routing function. This allows the via hole to be minimized for high routing density while the via land provides the necessary area for current dissipation, maintaining device reliability.
Solution Approach 2:
The solution moves from a single-dimension via size parameter to a two-dimension structure with distinct via hole and via land components. This dimensional change allows independent optimization of routing density (via hole size) and current handling (via land area).
3Reliability
If conventional via lands are used with traces, then current distribution is improved, but routing flexibility and density are reduced due to via land footprint
Solution Approach 1:
The via structure is segmented into a via hole and a via land, allowing the via land to be optimized for current distribution while the via hole positioning provides routing flexibility. This segmentation enables independent optimization of current distribution and routing adaptability.
Solution Approach 2:
The via land is designed with specific local properties (larger area) optimized for current distribution, while the via hole maintains a small size for routing flexibility. This local quality differentiation allows simultaneous achievement of good current distribution and high routing density.
Data Source
AI summary
Various circuit boards and methods of manufacturing the same are disclosed. In one aspect, a method of manufacturing is provided that includes forming a first interconnect layer of a circuit board. The first interconnect layer includes a first conductor trace with a first segment that does not include a via land. A first via is formed on the first segment.