Multi-Level Circuit Board Pads for Fine-Pitch Short Prevention
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Solution Overview
Problem
As semiconductor packages become more high-performance and miniaturized, the reduced bonding pad pitch leads to deterioration in connection characteristics, requiring improved methods to maintain stable connections while preventing short circuits.
Innovation Solution
A circuit board design featuring multiple pad portions with varying thicknesses and metal layers, including copper, nickel, and gold, buried and protruding from insulating layers, connected via a via layer to ensure stable connections and prevent shorts, along with a manufacturing method that forms these layers and insulating structures to maintain pitch reduction without compromising connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the bonding pad pitch is reduced to increase I/O connection terminals, then the density of the package is improved, but the connection characteristics deteriorate
Solution Approach 1:
The pad structure transitions from a conventional single-layer configuration to a multi-layer vertical structure. The first pad portion is formed in the first insulating layer, the second pad portion is formed in the second insulating layer, and they are electrically connected through a via layer. This three-dimensional arrangement allows multiple I/O terminals to be stacked vertically, increasing terminal density without reducing the horizontal pitch between pads, thereby maintaining connection characteristics while increasing the number of I/O connections.
Solution Approach 2:
The pad structure embeds multiple functional layers within each other: the first pad portion is embedded in the first insulating layer, the second pad portion is embedded in the second insulating layer, and the via layer connects them through the first insulating layer. This nested configuration allows multiple pad portions to occupy different vertical levels while maintaining electrical connectivity, effectively increasing the number of I/O terminals without compromising connection reliability.
2Quantity of substance
If the bonding pad pitch is reduced, then the number of I/O connection terminals increases, but short circuits may occur
Solution Approach 1:
By stacking pad portions in the vertical dimension rather than arranging them horizontally, the invention increases terminal density without reducing horizontal spacing. The via layer provides a controlled vertical connection path that is isolated from adjacent pads by insulating layers, preventing short circuits while enabling more I/O terminals.
Solution Approach 2:
The via layer acts as an intermediary connection element between the first pad portion and the second pad portion. It provides a controlled electrical connection through the first insulating layer while being surrounded by insulating material that prevents unwanted electrical contact with adjacent pads, thereby enabling increased terminal count without short circuit risks.
3Reliability
If multiple metal layers with different thicknesses are used in pad portions, then connection reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention applies different metal layers with different thicknesses locally to different pad portions based on their specific functional requirements. The first pad portion and second pad portion can have different metal compositions and thicknesses optimized for their respective connection needs, while sharing common manufacturing processes for forming the multi-layer structure and via connections.
Solution Approach 2:
The pad structure is segmented into multiple functional layers (first pad portion, second pad portion, via layer) with different metal compositions. Each layer can be independently optimized for its specific function while being formed through a systematic multi-step manufacturing process that deposits and patterns each metal layer separately, allowing for tailored connection properties without overwhelming complexity.
Data Source
AI summary
A circuit board includes: a first insulating layer; a second insulating layer positioned on the first insulating layer; and a first pad portion and a second pad portion which are partially buried in the first insulating layer, protrude from the second insulating layer, and have different thicknesses. The first pad portion and the second pad portion each include a first layer and a second layer positioned on the first layer, and heights of the first layer of the first pad portion and the first layer of the second pad portion are lower than a height of the first insulating layer.