Circuit Board Conductive Terminal Embedded Structure
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Solution Overview
Problem
The existing circuit board joining methods using solder balls are prone to breakage and require precise alignment, leading to reliability issues and reduced yield due to the exposure of pads.
Innovation Solution
A circuit board structure with a conductive terminal design featuring a first portion protruding from the insulating layer and second and third portions embedded within, utilizing a narrow top and wide bottom structure to enhance fixation and alignment tolerance, along with a manufacturing method involving wet etching to form openings for the conductive terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solder ball is used for joining, then the connection between pads is achieved, but the solder ball is easy to break at the interface resulting in reduced reliability
Solution Approach 1:
The conductive terminal is divided into three portions: a first portion protruding from the insulating layer, a second portion embedded in the insulating layer, and a third portion between the line portion and the second portion. This segmentation distributes mechanical stress across multiple interfaces rather than concentrating it at a single solder ball interface, thereby improving reliability while maintaining connection strength.
Solution Approach 2:
The conductive terminal is nested within the insulating layer, with the second portion embedded in the insulating layer and the third portion disposed between the line portion and the second portion. This nesting structure provides mechanical support and protection, preventing the conductive terminal from breaking at the interface while maintaining electrical connection.
2Manufacturing precision
If the opening of the solder mask is used to define the pad, then the pad location is defined, but precise alignment is required otherwise the pad is exposed causing abnormality and drop in yield
Solution Approach 1:
The conductive terminal has different width characteristics at different portions: the second portion has a greater width than the third portion, and the third portion has a first width greater than a second width. This local quality variation provides alignment tolerance, allowing the conductive terminal to be properly positioned without requiring precise alignment like traditional solder mask openings, thereby increasing yield.
3Reliability
If the conductive terminal has a narrow top and wide bottom structure, then the fixation is enhanced and alignment tolerance is increased, but the manufacturing process becomes more complex
Solution Approach 1:
The conductive terminal extends in the vertical dimension with three distinct portions at different heights: the first portion protrudes from the insulating layer surface, the second portion is embedded in the insulating layer, and the third portion is disposed between the line portion and the second portion. This multi-dimensional structure provides both fixation reliability and alignment tolerance without requiring complex lateral features.
Data Source
AI summary
The invention provides a circuit board structure and a manufacturing method thereof. The circuit board structure includes a line portion, a first insulating layer, and a conductive terminal. The first insulating layer is disposed on the line portion. The conductive terminal is disposed on the first insulating layer and embedded in the first insulating layer to be electrically connected with the line portion. The conductive terminal includes a first portion, a second portion, and a third portion. The first portion protrudes from a surface of the first insulating layer. The second portion is embedded in the first insulating layer and connected to the first portion. The third portion is disposed between the line portion and the second portion. A width of the second portion is greater than a width of the third portion.