Polymer Bump Structure with Grooves for Coupling Strength
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Solution Overview
Problem
Conventional gold bump structures on silicone substrates have insufficient contact area and are prone to displacement issues during bonding, leading to reduced coupling strength and potential short circuits, while also being costly due to the use of gold.
Innovation Solution
A bump structure comprising polymer blocks, grooves, an under bump metallurgy layer, and a connection metal layer, where the polymer blocks and grooves enhance contact area and prevent displacement by allowing the contact to be inserted into grooves and slots, and the polymer blocks serve as cost-effective base materials for electroplating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional gold bump structure is used, then the coupling strength is sufficient, but the production cost is high
Solution Approach 1:
The bump structure uses a composite design combining polymer blocks (first and second polymer blocks) with metal layers (under bump metallurgy layer and connection metal layer). This composite structure replaces expensive gold bumps while maintaining coupling strength through the combination of polymer's mechanical properties and metal's electrical conductivity and bonding strength.
Solution Approach 2:
The structure employs a nested configuration where the under bump metallurgy layer is formed over the polymer blocks and bond pad, and the connection metal layer is formed over the under bump metallurgy layer. This multi-layer nested structure achieves both mechanical support and electrical connection functions without requiring expensive gold material throughout.
2Device complexity
If a conventional gold bump structure is used, then the structure is simple, but the contact area is insufficient leading to reduced coupling strength
Solution Approach 1:
The connection slots extend vertically through multiple layers (polymer blocks, under bump metallurgy layer, and connection metal layer), creating a three-dimensional connection path. This vertical dimensionality increases the contact area between the bump structure and the contact, improving coupling strength while maintaining structural organization.
Solution Approach 2:
The bump structure is segmented into distinct functional layers: polymer blocks for mechanical support, under bump metallurgy layer for electrical connection, and connection metal layer for enhanced bonding. The connection slots are also segmented to pass through each layer sequentially, allowing each segment to contribute to the overall coupling strength.
3Ease of manufacture
If a conventional gold bump structure is used, then the manufacturing process is simple, but displacement occurs during coupling causing short circuits
Solution Approach 1:
The polymer blocks are positioned at two sides of the first groove and disposed on the bond pad and protecting layer before the metallurgy layers are formed. These polymer blocks act as cushioning elements that absorb and distribute mechanical stress during the coupling process, preventing displacement of the bump structure and avoiding short circuits between adjacent contacts.
Solution Approach 2:
The polymer blocks provide localized mechanical support and stress distribution at critical positions (sides of the groove), while the metallurgy layers provide electrical connection. This local differentiation of material properties addresses displacement resistance where needed without complicating the overall manufacturing process.
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 enhanced contact area and structural design increase coupling strength, prevent displacement, and reduce production costs by utilizing polymer blocks for electroplating, while also preventing short circuits by allowing anisotropic conductive film to flow freely between bumps.
Implementation Method 1
the bump structure may utilize the first polymer block and the second polymer block as base materials for cost savings of electroplating
Data Source
AI summary
A bump structure comprises a first polymer block, a second polymer block, a first groove, an under bump metallurgy layer and a connection metal layer, wherein the first polymer block and the second polymer block are individual blocks. The first polymer block and the second polymer block are located at two sides of the first groove, the first polymer block comprises a first connection slot, and the second polymer block comprises a second connection slot communicated with the first connection slot and the first groove. The under bump metallurgy layer covers the first polymer block and the second polymer block to form a second groove, a third connection slot and a fourth connection slot communicated with each other. The connection metal layer covers the under bump metallurgy layer to form a third groove, a fifth connection slot and a sixth connection slot communicated with each other.