Wiring Substrate Metal Post Oxidation Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The oxidation of copper metal posts on wiring substrates for semiconductor elements reduces the reliability of connections between the metal posts and electronic components due to exposure of their surfaces, leading to potential corrosion and adhesion issues during semiconductor mounting.
Innovation Solution
A wiring substrate design featuring an outer coating plating layer that entirely covers the upper and side surfaces of copper metal posts, formed through an electrolytic plating process with a thinner side portion to prevent oxidation and corrosion, and includes a seed layer and diffusion prevention layers to enhance connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the surfaces of copper metal posts are exposed to the outside, then the connection terminals can be easily formed, but the surfaces of the metal posts easily oxidize which lowers connection reliability
Solution Approach 1:
A plating layer is introduced as an intermediary substance between the copper metal post and the external environment. This plating layer serves as a protective barrier that prevents direct contact between oxygen and the copper surface, thereby preventing oxidation while allowing the metal post to function as a connection terminal. The plating layer acts as a mediator that maintains both the electrical connectivity function and the protection from environmental degradation.
2Reliability
If the metal posts are completely covered to prevent oxidation, then connection reliability improves, but the structural complexity and manufacturing process become more complex
Solution Approach 1:
The plating layer thickness is optimized to provide sufficient protection against oxidation while maintaining manufacturing feasibility. By carefully controlling the thickness parameter of the plating layer, the solution achieves adequate corrosion protection without excessive material usage or manufacturing complexity. The thickness is sufficient to prevent oxidation but thin enough to be applied through standard plating processes.
3Object-affected harmful factors
If a thick plating layer is applied to entirely cover the metal post, then oxidation prevention is effective, but galvanic corrosion and adhesion issues may occur
Solution Approach 1:
The plating layer is applied with varying thickness across different regions of the metal post. The thickness is optimized locally to provide adequate protection where needed while minimizing the risk of galvanic corrosion. This local variation in plating quality allows the structure to achieve effective oxidation prevention without creating conditions favorable for galvanic corrosion or adhesion problems.
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 limits oxidation of the metal posts, improves connection reliability by reducing galvanic corrosion and adhesion issues, and maintains the structural integrity of the metal posts during semiconductor mounting.
Implementation Method 1
a metal layer formed by an electrolytic copper plating layer on the seed layer located in the opening
Implementation Method 2
the surfaces of the metal posts easily oxidize. Oxidation of the metal posts lowers the reliability of the connection
Data Source
AI summary
A wiring substrate includes a wiring layer and an insulation layer covering the wiring layer. The insulation layer includes an opening partially exposing the wiring layer. A seed layer continuously covers a wall surface of the opening and an upper surface of the insulation layer. The wiring substrate also includes a metal layer, a metal post, and an outer coating plating layer. The opening is filled with the seed layer and the metal layer formed on the seed layer. The metal post is formed on the metal layer and on the seed layer that is located on the insulation layer. The outer coating plating layer includes an upper portion, entirely covering an upper surface of the metal post, and a side portion, entirely covering a side surface of the metal post and exposing an outer end surface of the seed layer. The side portion is thinner than the upper portion.