Flip Chip Packaging De-void Process for Bubble Elimination
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Solution Overview
Problem
The existing flip chip packaging methods face challenges with bubble formation during the use of non-conductive films, which affects the reliability of the soldering joints and increases manufacturing costs due to high equipment costs and longer processing times.
Innovation Solution
A flip chip package manufacturing method that includes a thermo-compression bonding process with a de-void process in a pneumatic and heatingable chamber to eliminate bubbles between the carrier and non-conductive film, and within the film itself, followed by a high-temperature soldering process to ensure reliable bonding without the need for liquid resin filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-conductive film is used with thermo-compression bonding, then bonding accuracy and reliability are improved, but bubble formation occurs and processing time increases
Solution Approach 1:
The non-conductive film is pre-laminated onto the wafer before the flip chip bonding process, preparing the structure in advance to prevent bubble formation during subsequent bonding operations. This preliminary preparation ensures proper film positioning and reduces processing time during the actual bonding step.
Solution Approach 2:
The patent applies preliminary anti-action by pre-heating and pre-pressing the non-conductive film to eliminate potential bubbles before the main bonding process. This counteracts the bubble-forming tendency that would otherwise occur during thermo-compression bonding, ensuring reliable soldering joints without extending overall processing time.
2Reliability
If non-conductive film is used with high-temperature compression, then adhesion and reliability are improved, but equipment cost and process complexity increase
Solution Approach 1:
The patent merges the non-conductive film application and flip chip bonding processes into a single integrated step. The film is laminated onto the wafer before flipping and bonding, combining multiple functions (insulation, adhesion, and structural support) into one unified process flow, thereby reducing equipment complexity while maintaining high reliability.
Solution Approach 2:
The non-conductive film serves multiple functions simultaneously: electrical insulation, mechanical adhesion support, and bubble prevention. This multi-functionality reduces the need for separate process steps and equipment, lowering overall system complexity while achieving improved mechanical and electrical characteristics.
3Reliability
If multiple reflow heating processes are applied, then soldering is improved, but conductive bump oxidation and adhesion reduction occur
Solution Approach 1:
The patent employs an inert atmosphere (nitrogen or vacuum environment) during the heating and bonding processes to prevent oxidation of conductive bumps. This inert environment allows for effective soldering while protecting the bump surfaces from oxidative damage, maintaining adhesion quality even after multiple heating cycles.
Solution Approach 2:
The patent implements continuous heating without intermediate cooling steps, maintaining the inert atmosphere throughout the entire process. This continuous action prevents oxidation by eliminating exposure to oxygen during transitions, ensuring soldering quality while protecting conductive bumps from harmful oxidation effects.
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 method effectively reduces bubble-related failures, lowers manufacturing costs, and simplifies the packaging process by eliminating bubbles and improving the reliability of the soldering joints while reducing processing time and equipment costs.
Implementation Method 1
a heating process is executed to heat the non-conductive film and melt the conductive bump
Implementation Method 2
transferring the carrier into a chamber, and executing a de-void process in the chamber to eliminate at least one first bubble
Data Source
AI summary
A flip chip package manufacturing method is provided. A non-conductive film is pressed onto a wafer with multiple conductive bumps. The wafer is cut to multiple single chips. A carrier is provided, and a thermo-compression flip chip bonding process is executed to bond the non-conductive film onto the carrier. The carrier is transferred into a chamber with enclosed, pneumatic pressurized and heatingable characteristics to execute a de-void process to eliminate the bubbles and to execute a high-temperature soldering process to solder the single chip onto the carrier. The sequence of the de-void process and the high-temperature soldering process may exchange.