Wiring Board Electroplating Void Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wiring board production processes often result in air gaps (voids) within metal layers filled in through holes, reducing the reliability of the wiring board and requiring complex processes to close through holes with metal layers, which increases production time and metal usage.
Innovation Solution
A process involving an insulating substrate with a through hole, where a seed layer is formed and covered with a masking film, allowing electroplating to fill the hole without initially closing it, followed by removing the masking film and forming additional metal layers to prevent voids and reduce metal thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electroplating is carried out to fill the through hole with a metal layer without closing the through hole first, then the void generation is reduced, but the metal layer thickness cannot be controlled and production time increases
Solution Approach 1:
The electroplating process is divided into two distinct stages: first forming a seed layer through the through hole, then forming the final metal layer after closing the through hole with a plug. This segmentation allows each stage to be optimized independently - the seed layer ensures void-free filling while the plug enables precise thickness control of the final metal layer, resolving the contradiction between void prevention and production efficiency
Solution Approach 2:
A plug structure is formed preliminarily to close the through hole before forming the final metal layer. This preliminary action enables precise control of the metal layer thickness in the subsequent electroplating process while maintaining the void-free characteristics established during the seed layer formation stage, thus reducing production time without sacrificing reliability
2Manufacturing precision
If the through hole is closed with a metal layer before electroplating, then the metal layer thickness can be controlled, but voids are generated in the electroplated metal layer
Solution Approach 1:
The metal layer formation is segmented into two parts: a seed layer formed by electroplating through the open through hole (ensuring void-free structure), and a final metal layer formed after the through hole is closed with a plug (enabling precise thickness control). This segmentation resolves the contradiction by assigning different functions to different stages
Solution Approach 2:
The plug is formed preliminarily to close the through hole before the final metal layer is deposited. This preliminary closure enables precise thickness control of the final metal layer while the earlier seed layer formation stage ensures no voids are generated, thus resolving the contradiction between precision and reliability
3Reliability
If a complex process is used to close the through hole with a metal layer, then voids are prevented, but the device complexity and metal usage increase
Solution Approach 1:
The plug formation and metal layer formation processes are merged into a unified two-stage electroplating sequence. The plug is formed by electroplating metal to close the through hole, and the final metal layer is formed by continuing electroplating on the closed structure. This merging simplifies the overall process while maintaining void prevention and enabling thickness control
Solution Approach 2:
The plug is formed as a preliminary structure using the same electroplating process that forms the metal layer. This preliminary action closes the through hole to enable precise thickness control and simplify subsequent processing, while the earlier seed layer formation ensures void-free structure, thus reducing process complexity without sacrificing reliability
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
This process effectively prevents voids in metal layers, reduces production time, minimizes metal usage, and produces a smooth electrode without the need for complex post-processing, enhancing the reliability and efficiency of wiring board production.
Implementation Method 1
carrying out electroplating to form a metal layer in the through hole
Data Source
Figure 1(a)~1(j)
Figure 2(a)~2(g)
Figure 3
AI summary
A process for efficiently producing a wiring board in which an insulating substrate 1 having a through hole 2 is used, which includes forming a seed layer 3 on one surface of the insulating substrate 1, covering the surface of the insulating substrate 1 on which the seed layer 3 is formed with a masking film 4, arranging the insulating substrate 1 and a positive electrode 5 so that the surface of the insulating substrate 1 opposite to the surface of the insulating substrate 1 on which the seed layer 3 of the insulating substrate 1 is formed is faced to the positive electrode 5, carrying out electroplating to form a metal layer 8 in the through hole 2, and then removing the masking film 4.