Flip Chip Gold Bump Manufacturing Using Unified Seed Layer
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Solution Overview
Problem
The existing flip chip packaging methods using gold bumps require complex processes involving the formation and removal of metal seed layers for electroplating, which complicates the manufacturing process and makes it difficult to evaluate the electrical characteristics of the gold bumps before they are bonded to the substrate.
Innovation Solution
A method where the metal seed layer used for electroplating is directly utilized as a metal pattern for forming electrical connections between gold bumps, allowing for the omission of the processes of forming and removing electrode wires, and enabling the evaluation of electrical functions between bumps, while also unifying the photolithography masks for plating and insulating layer patterning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal seed layer is formed for electroplating and then removed after gold bump formation, then the gold bump can be formed successfully, but the manufacturing process becomes complicated and electrical characteristics cannot be evaluated
Solution Approach 1:
The patent merges the metal seed layer with the final metal pattern by using the same layer for both electroplating and electrical connection. The metal pattern is formed by patterning the seed layer itself rather than adding a separate electrode wire layer, thereby eliminating the need to form and remove temporary electrode wires while maintaining electrical functionality.
Solution Approach 2:
The metal seed layer serves multiple functions: it acts as the electroplating substrate for gold bump formation, provides the final metal pattern for electrical connections between bumps, and enables electrical characteristic evaluation. This multi-functional design eliminates the need for separate electrode wires and simplifies the manufacturing process.
2Ease of manufacture
If electrode wires are formed for electroplating, then the gold bump can be formed, but additional processes are required before and after bump formation causing inconvenience
Solution Approach 1:
The patent combines the electroplating substrate function and the final electrical connection function into a single metal pattern layer. This eliminates the need for separate electrode wire formation and removal processes, reducing the number of manufacturing steps and improving production efficiency.
3Manufacturing precision
If the entire metallic seed layer is etched after gold bump formation, then only the gold bump remains, but it becomes impossible to evaluate electrical characteristics
Solution Approach 1:
The patent merges the metal seed layer with the final metal pattern, so the seed layer remains after electroplating to provide both electrical connections and evaluation pathways. This allows electrical characteristics to be measured while maintaining the precision of gold bump formation.
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 approach simplifies the manufacturing process, reduces material and process costs, and enhances the reliability of flip chip packages by allowing direct evaluation of electrical functions and reducing unnecessary steps, leading to more efficient production with unified mask usage.
Implementation Method 1
A method for forming a gold bump includes an electroplating method
Data Source
AI summary
Disclosed is a method for manufacturing a flip chip, in which a gold typically used in a flip chip manufacturing is adhered by conductive adhesives, wherein the method comprises steps of depositing a metal seed layer on a substrate; applying and patterning a photoresist or a dry film; forming a gold bump by electroplating; patterning the seed layer; forming an insulating layer on the seed layer and upper end of the gold bump; and patterning an insulating layer. Accordingly, it is possible to manufacture a flip chip, in which electrical function between bumps can be evaluated, with less cost.