Printed Wiring Board Metal Post Adhesion via Segmented Seed Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing printed wiring boards face issues with adhesion between the seed layer and the outermost insulating layer due to excessive etching of the seed layer, leading to poor contact and reliability with external components.
Innovation Solution
A printed wiring board design featuring a metal post with a seed layer and an electrolytic plating layer, where the seed layer has a first layer and a second layer, and the electrolytic plating layer is formed to exceed the height of the outermost insulating layer, with the width of the first layer being larger than the second layer and the electrolytic plating layer being wider than the first layer, ensuring improved adhesion and connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the seed layer is etched to form the metal post structure, then the metal post can be formed with distinct layers, but excessive etching causes poor adhesion between the seed layer and the outermost insulating layer
Solution Approach 1:
The seed layer is designed with non-uniform thickness where the first region (at the interface with outermost insulating layer) has greater thickness than the second region. This local quality variation ensures strong adhesion at the critical interface while allowing sufficient etching to form the metal post structure, resolving the contradiction between manufacturing precision and adhesion reliability.
2Reliability
If the metal post height exceeds the outermost insulating layer, then connection reliability with external components is improved, but the surface finish becomes rough
Solution Approach 1:
The metal post is segmented into distinct functional regions: the electrolytic plating layer forms the protruding connection portion exceeding the insulating layer surface, while the seed layer forms the base structure within the insulating layer. This segmentation allows the connection portion to provide reliable external connections while the base structure maintains a smooth surface finish, resolving the contradiction between connection reliability and surface quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design enhances adhesion between the metal post and external components, reduces excessive etching, and maintains a smooth surface finish, resulting in improved connection reliability and quality of the printed wiring board.
Implementation Method 1
an electrolytic plating layer formed on the seed layer
Data Source
AI summary
A printed wiring board includes a conductor layer, an outermost insulating layer formed on the conductor layer and having an opening exposing a portion of the conductor layer, and a metal post formed in the opening of the outermost insulating layer and including a seed layer and an electrolytic plating layer formed on the seed layer such that the metal post has a height exceeding a surface of the outermost insulating layer and has a portion exceeding a height of the outermost insulating layer, the seed layer of the metal post has a first layer and a second layer formed on the first layer. The portion exceeding the height of the outermost insulating layer is formed such that a width of the first layer is larger than a width of the second layer, and a width of the electrolytic plating layer is larger than the width of the first layer.