Conductive Posts for Printed Wiring Board Connection Reliability
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Solution Overview
Problem
Existing printed wiring boards with embedded conductor patterns face challenges in maintaining reliable connections with electronic components due to warping and stress issues, especially when the conductor pattern is embedded within the insulating layer, leading to potential electrical shorts and reduced reliability.
Innovation Solution
A method for manufacturing printed wiring boards with conductive posts involves forming a conductive layer on a metallic foil, laminating a resin insulating layer, creating holes for via conductors, and using electroplating and etching to form conductive posts that protrude from the resin surface, allowing for direct electrical connection to electronic components without joining materials, thereby alleviating stress and preventing shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conductor pattern is embedded within the insulating layer, then the wiring board structure is compact and integrated, but the connection reliability with electronic components deteriorates due to warping and stress issues
Solution Approach 1:
The conductor pattern is segmented into two parts: an embedded portion within the insulating layer and a protruding portion extending outward. This segmentation allows the conductor to maintain both the compact embedded structure and the reliable exposed connection point, resolving the contradiction between embedding precision and connection reliability.
Solution Approach 2:
The conductor pattern transitions from a purely planar embedded structure to a three-dimensional structure with both embedded and protruding portions. This dimensional change enables the conductor to achieve both compact integration and reliable external connections, overcoming the limitations of flat embedded patterns.
2Quantity of substance
If the conductor pattern is embedded in the insulating layer, then the wiring density is increased, but the stress and warping issues increase leading to electrical shorts
Solution Approach 1:
A portion of the conductor pattern is extracted from the embedded structure and extended outward to form protruding conductive posts. This extraction reduces the stress concentration within the insulating layer and prevents warping-induced electrical shorts while maintaining high wiring density through the embedded portions.
Solution Approach 2:
The protruding conductive posts serve as a cushioning mechanism that absorbs stress and prevents warping from causing electrical shorts. By providing this stress relief path beforehand, the structure maintains high wiring density without suffering from warping-related failures.
3Reliability
If conductive posts protrude from the resin surface, then the connection reliability with electronic components is improved, but the manufacturing process complexity increases
Solution Approach 1:
The formation of protruding conductive posts is merged with the existing electroplating process for via conductors. By using the same electroplating step to form both via conductors and protruding posts, the manufacturing process complexity is minimized while achieving improved connection reliability.
Solution Approach 2:
The electroplating process serves multiple functions: forming via conductors within the insulating layer and simultaneously creating protruding conductive posts on the surface. This multi-functionality reduces the need for additional manufacturing steps while improving connection reliability.
4Shape
If the conductor pattern is embedded in the insulating layer, then the wiring board structure is compact, but the risk of electrical shorts increases due to warping
Solution Approach 1:
The protruding conductive posts act as an intermediary between the embedded conductor pattern and the external electronic components. This intermediary structure maintains the compact embedded design while providing a stable connection point that is isolated from warping-induced electrical shorts.
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 method ensures reliable connections between the printed wiring board and electronic components by allowing conductive posts to protrude from the resin surface, reducing stress and preventing electrical shorts, while enabling efficient manufacturing with high reliability and reduced warping risks.
Implementation Method 1
applying electroplating on the portion of the metal film exposed by the pattern of the plating resist film such that an electroplating conductive layer is formed on the portion of the metal film not covered by the plating resist film
Implementation Method 2
applying etching removal on the portion of the metal film exposed by the removing of the plating resist film such that portion of the first metallic foil and second metallic foil below the portion of the metal film exposed by the removing of the plating resist film is removed
Data Source
AI summary
A method for manufacturing a printed wiring board with conductive posts includes forming on a first foil provided on carrier a first conductive layer including mounting pattern to connect electronic component via conductive posts, forming on the first foil a laminate including an insulating layer and a second foil to form the laminate on the first conductive layer, removing the carrier, forming a metal film on the laminate and first film, forming resist on the metal film to have pattern exposing portion of the metal film corresponding to the mounting pattern and portion of the second foil for a second conductive layer, forming an electroplating layer on the portion of the metal film not covered by the resist, removing the resist, and applying etching to remove the first and second foils below the metal film exposed by the removing the resist and to form the posts on the mounting pattern.