Printed Wiring Board Metal Posts with Flared Bottoms
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Solution Overview
Problem
Existing printed wiring board manufacturing processes face challenges in maintaining the thickness and adhesion of peeling prevention layers during etching, leading to potential short circuits and reduced connection reliability due to the removal of copper-based seed layers.
Innovation Solution
A printed wiring board design featuring a resin insulating layer with exposed pads, via conductors, metal posts with flared bottoms, and plating films covering the metal posts and resin insulating layer, which prevents partial removal of metal posts during etching and ensures high adhesion and connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If copper-based seed layers are used for metal posts, then ease of manufacture is improved, but the seed layers are partially removed during etching leading to thinning of metal posts and reduced connection reliability
Solution Approach 1:
The patent applies preliminary action by forming a protective film on the metal posts before the etching process. This protective film is formed in advance to prevent the harmful effect of etching solution contact, thereby preventing partial removal of the metal posts during subsequent etching operations while maintaining ease of manufacture
Solution Approach 2:
The patent introduces an intermediary substance (protective film) between the etching solution and the metal posts. This protective film acts as a mediator that allows the etching process to proceed while preventing direct contact between the etching solution and the metal post surface, thus preventing thinning and maintaining connection reliability
2Ease of manufacture
If metal posts are formed with standard geometry, then ease of manufacture is improved, but partial removal during etching causes short circuits
Solution Approach 1:
The protective film is formed on the metal posts before etching as a preliminary protective measure. This preliminary action prevents the harmful effect of etching solution contact, thereby preventing partial removal that could lead to short circuits while maintaining standard manufacturing simplicity
Solution Approach 2:
The patent converts the potentially harmful etching process into a beneficial operation by using the protective film to prevent unwanted etching of the metal posts. The etching solution is allowed to contact the structure, but the protective film ensures that only non-critical areas are etched, preventing short circuits while maintaining manufacturing efficiency
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 solution effectively suppresses the thinning of metal posts and enhances connection reliability between metal posts, via conductors, and pads, while preventing short circuits by covering the metal posts and resin insulating layer with plating films.
Implementation Method 1
plating films covering the metal posts and resin insulating layer, which prevents partial removal of metal posts during etching
Implementation Method 2
a side surface having a flared bottom extending toward the uppermost resin insulating layer
Data Source
AI summary
A printed wiring board includes a resin insulating layer, pads formed on the resin insulating layer, an uppermost resin insulating layer formed on the resin insulating layer such that the uppermost resin insulating layer is covering the pads and has openings exposing the pads, respectively, via conductors formed in the uppermost resin insulating layer such that the via conductors are formed on the pads exposed from the openings in the uppermost resin insulating layer, respectively, and metal posts formed on the via conductors such that each of the metal posts has a portion on a surface of the uppermost resin insulating layer around the via conductors and a side surface having a flared bottom extending toward the uppermost resin insulating layer.