Flip Chip Flux Printing and Pressure Cleaning for Dense Substrates
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Solution Overview
Problem
Conventional flip chip packaging processes face challenges in effectively cleaning residual adhesive and oxide residues, especially as wiring substrates become denser and components smaller, leading to reduced reliability and environmental concerns.
Innovation Solution
A process utilizing a 3D array nozzle printing device to accurately control the spraying range and dose of welding flux, combined with a liquid material and gas flow fluctuation with intermittent pressure changes, to enhance cleaning efficiency and reduce residual flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cleaning solvents and methods are used to remove residual adhesive and oxide residues, then cleaning can be performed, but cleaning effectiveness deteriorates when wiring substrates become denser and gaps become narrower
Solution Approach 1:
The patent changes the physical and chemical parameters of the cleaning agent by using welding flux with specific acid content and composition parameters. The welding flux contains acids capable of dissolving oxide residues and organic matter, with controlled concentration and viscosity parameters to ensure effective penetration into narrow gaps while maintaining cleaning effectiveness on dense wiring substrates.
Solution Approach 2:
The patent converts the harmful corrosive nature of the welding flux into a beneficial cleaning mechanism. The acid content that would normally be considered harmful is utilized to effectively dissolve and remove adhesive residues and oxide layers from the bonding surfaces, transforming a potential reliability issue into a solution for complete residue removal.
2Strength
If corrosive adhesives with high acid content are used to remove oxide layers, then bonding effectiveness is improved, but component reliability deteriorates due to residual adhesive and corrosion
Solution Approach 1:
The patent converts the harmful corrosive nature of the welding flux into a beneficial cleaning mechanism. The acid content that would normally be considered harmful is utilized to effectively dissolve and remove adhesive residues and oxide layers from the bonding surfaces, transforming a potential reliability issue into a solution for complete residue removal.
Solution Approach 2:
The patent extracts and removes the harmful residual adhesive and oxide residues from the bonding interface using the welding flux. By applying the flux before or during the bonding process, the harmful substances are dissolved and removed, leaving only the desired metal-to-metal bonding without corrosive residues that would compromise component reliability.
3Reliability
If multiple cleaning steps are performed to remove residues, then reliability is improved, but production efficiency deteriorates
Solution Approach 1:
The patent merges the cleaning function with the bonding process by applying welding flux that serves dual purposes: removing oxide residues and facilitating metal bonding. This combination eliminates separate cleaning steps, achieving both reliability improvement through complete residue removal and production efficiency enhancement by reducing process steps.
Solution Approach 2:
The patent performs the cleaning action preliminarily by applying welding flux before or during the bonding process. This preliminary cleaning ensures that all residues are removed before bonding occurs, eliminating the need for subsequent cleaning steps and streamlining the production process while maintaining high reliability standards.
4Manufacturing precision
If conventional cleaning processes are used, then environmental impact is moderate, but cleaning effectiveness on dense substrates deteriorates
Solution Approach 1:
The patent changes the parameters of the cleaning agent by using welding flux with controlled acid content and composition. The flux is formulated to be effective at removing residues from dense substrates while being manageable in terms of environmental disposal, balancing cleaning effectiveness with environmental considerations through optimized chemical parameters.
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 process significantly reduces residual welding flux and improves cleaning benefits, simplifying the flip chip packaging process and enhancing production efficiency while minimizing environmental impact.
Implementation Method 1
a liquid material 410 and gas flow fluctuation with intermittent pressure increasing and reducing to drive the liquid material to cause a rubbing or stirring effect
Implementation Method 2
causing a fluctuation change of the liquid material to generate a back-and-forth rubbing cleaning effect like laundry
Data Source
AI summary
A process for flip chip packaging includes: preparing a chip provided with a plurality of conductive bumps; preparing a wiring substrate, on which a respective welding pad is configured correspondingly to each of the conductive bumps; spraying a welding flux on each of the welding pads by utilizing a 3D array nozzle printing device; flipping and aligning the chip, and performing a metal welding operation to form a flip chip package structure; filling a liquid material to cover a substance to be cleaned on the wiring substrate; placing the flip chip package structure in a closed processing chamber, and heating the processing chamber to a predetermined temperature; and generating intermittent increasing/reducing pressure and/or intermittent vacuumizing for a gas in the processing chamber with a pressure increasing/reducing device and/or a vacuum generator, so that the substance to be cleaned is taken away from the wiring substrate.