Wiring Substrate Seed Layer Segmentation for Thermal Stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current multilayer substrates face challenges in forming reliable via conductors that connect through-hole conductors to conductor layers on glass substrates, particularly in maintaining electrical connectivity and mechanical stability under thermal stress.
Innovation Solution
A wiring substrate design featuring a glass core substrate with through-hole conductors, a resin insulating layer, and via conductors formed by a seed layer and electrolytic plating layer, where the seed layer has a smooth, step-shaped cross-section to enhance bonding and reduce peeling, and the via conductors electrically connect through-hole conductors to conductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional seed layer is formed on the inner wall surface of the opening, then the via conductor can be formed, but the seed layer peels off due to thermal expansion difference between glass and resin, causing poor reliability
Solution Approach 1:
The seed layer is divided into two distinct portions: a first portion formed on the inner wall surface of the opening, and a second portion formed on the through-hole conductor. This segmentation allows each portion to independently accommodate thermal expansion differences between glass and resin substrates, preventing peeling and maintaining electrical connectivity reliability under thermal stress.
2Ease of manufacture
If the inner wall surface of the opening is rough, then the seed layer can be formed, but the surface is unsuitable for forming fine signal wirings
Solution Approach 1:
The patent applies different surface quality requirements to different locations: the inner wall surface of the opening is designed with a rough surface to facilitate seed layer formation and ensure good adhesion, while the outer surface of the through-hole conductor is designed with a smooth surface to enable the formation of fine signal wirings. This local differentiation of surface properties resolves the contradiction between ease of manufacture and manufacturing precision.
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 ensures strong electrical connectivity and mechanical stability, reducing transmission loss and maintaining performance under thermal stress, while allowing for the formation of fine signal wirings on smooth surfaces.
Implementation Method 1
a conductor layer formed on the resin insulating layer and including a seed layer and an electrolytic plating layer formed on the seed layer, and a via conductor formed in the resin insulating layer such that the via conductor electrically connects the through-hole conductor and the conductor layer and that the via conductor includes the seed layer and electrolytic plating layer extending from the conductor layer
Data Source
AI summary
A wiring substrate includes a core substrate having a through-hole conductor, a resin insulating layer formed on the core substrate, a conductor layer formed on the insulating layer and including a seed layer and an electrolytic plating layer, and a via conductor formed in the insulating layer. The via conductor electrically connects the through-hole conductor and conductor layer. The via conductor includes the seed layer and electrolytic plating layer extending from the conductor layer. The core substrate includes a glass substrate and has a through hole penetrating through the glass substrate. The through-hole conductor is formed in the through hole. The seed layer is covering inner wall surface of the insulating layer in opening in which the via conductor is formed. The seed layer has a first portion and a second portion electrically connected to the first portion. That part of the first portion is formed on the second portion.