Multi-Layer Substrate Bond Pad Embedding and Cover Metal Barrier
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing surface finish structures of multi-layer substrates face issues with delamination and peeling of bond pad layers due to material stress and humidity, leading to unreliable connections with solder, which compromises the reliability and yield of packaged products.
Innovation Solution
Embedding the bond pad layer within the dielectric layer and forming cover metal layers before coating the solder mask to create a barrier, ensuring the bond pad layer is securely anchored and preventing solder contact, even under environmental stress or delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the bond pad layer is formed on the dielectric surface, then the manufacturing process is simple, but the bond pad layer may peel or delaminate from the dielectric layer due to stress and humidity
Solution Approach 1:
The bond pad layer is embedded within the dielectric layer, with the dielectric layer surrounding and anchoring the bond pad layer. This nested structure prevents peeling and delamination by providing mechanical support from multiple sides, resolving the adhesion reliability issue while maintaining manufacturing simplicity
Solution Approach 2:
The bond pad layer transitions from a surface-mounted 2D structure to a partially embedded 3D structure within the dielectric layer. This dimensional change provides anchoring effect and prevents delamination, improving reliability without significantly complicating the manufacturing process
2Ease of manufacture
If cover metal layers are formed after coating the solder mask, then the manufacturing process follows conventional steps, but delamination may occur due to stress between different materials
Solution Approach 1:
The cover metal layers are formed on the bond pad layer before coating the solder mask. This preliminary action ensures that the cover metal layers are already in place to prevent solder contact and reduce stress-related delamination, improving interface adhesion reliability while maintaining conventional manufacturing steps
Solution Approach 2:
The cover metal layers are formed in advance to provide a protective barrier and stress buffer between the bond pad layer and the subsequent solder mask layer. This beforehand cushioning prevents delamination caused by material stress and humidity, improving long-term reliability
3Ease of manufacture
If the bond pad layer is exposed to solder during processing, then the manufacturing process is straightforward, but wetting phenomenon occurs and IMC layer formation weakens the connection
Solution Approach 1:
The cover metal layers (nickel and gold) serve as intermediary barrier layers between the bond pad layer (copper) and the solder. This intermediary structure prevents direct contact between copper and solder, eliminating wetting phenomenon and preventing fragile IMC layer formation, thereby maintaining connection strength and reliability
Data Source
AI summary
A surface finish structure of multi-layer substrate and manufacturing method thereof. The surface finish structure of the present invention includes a bond pad layer, at least one cover metal layer and a solder mask. The cover metal layer covers the bond pad layer. The solder mask has a hole to expose the cover metal layer. The present invention can form the cover metal layer to cover the bond pad layer and then forms the solder mask. Thereafter, the hole is made to the solder mask at the position of the cover metal layer to expose thereof. Because the bond pad layer is embedded in a dielectric layer of the multi-layer substrate, adhesion intensity between the bond pad layer and the dielectric layer can be enhanced. Meanwhile, contact of the bond pad layer with the solder can be prevented with the cover metal layer.