Underfill Void Removal Using Alternating Vacuum-Pressure Cycles
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Solution Overview
Problem
The capillary underfill process in electronic component assembly often results in voids due to variations in underfill solution speed and distribution, which are exacerbated by the increasing integration and miniaturization of solder balls, affecting the reliability of the product.
Innovation Solution
A device utilizing a chamber with a gas supply and vacuum system to alternately create pressurizing and vacuum atmospheres, along with optional heating, to manipulate the voids within the underfill material, facilitating their contraction and expansion for removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the capillary underfill process is used to fill the space between substrate and electronic component, then the underfill solution can move forward by capillary force, but voids occur due to speed differences caused by solder balls
Solution Approach 1:
The patent applies periodic vacuum and pressure cycles to the underfill material. The vacuum device creates negative pressure to draw out air and volatiles from voids, while the pressure device applies positive pressure to force the underfill material into void spaces. This periodic alternation continues for multiple cycles to progressively eliminate voids while maintaining the capillary filling action
Solution Approach 2:
The patent changes the pressure parameter of the underfill material during the filling process. By alternating between vacuum (negative pressure) and pressure (positive pressure) conditions, the physical state of the underfill material and the voids within it are modified, enabling void removal while maintaining effective filling
2Adaptability or versatility
If solder ball size is decreased and number is increased for higher integration, then electronic component integration improves, but void occurrence probability increases
Solution Approach 1:
The periodic vacuum-pressure cycling addresses void formation issues that arise with higher integration and more numerous solder balls. Each cycle draws out air and volatiles from the increased number of smaller voids created by the higher density of solder balls, maintaining product reliability despite increased integration
Solution Approach 2:
The multiple cycles of vacuum and pressure application ensure continuous action to eliminate voids. Rather than a single treatment, the process repeats several times to progressively remove voids that form during filling of highly integrated components with numerous small solder balls
3Reliability
If vacuum and gas supply devices operate alternately to create vacuum and pressurizing atmospheres, then voids can be removed through pressure changes, but device complexity increases
Solution Approach 1:
The chamber structure serves multiple functions: it contains the substrate during filling, accommodates the vacuum device for void removal, and provides the sealed environment needed for pressure cycling. This multi-functionality reduces the need for separate dedicated structures for each function
Solution Approach 2:
The vacuum device and gas supply device are integrated into a coordinated system that operates through the same chamber. The controller synchronizes both devices to work together in alternating cycles, combining what could be separate independent systems into a unified void removal 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
Efficiently removes voids in the underfill material by rapidly changing internal pressures and temperatures, ensuring uniform distribution and enhancing the reliability of electronic component assembly.
Implementation Method 1
a vacuum device connected to the chamber and configured to exhaust a gas from the inside of the chamber to outside of the chamber to create a vacuum atmosphere inside the chamber
Implementation Method 2
a gas supply device connected to the chamber and configured to inject a heated gas into the chamber to create a heating atmosphere and a pressurizing atmosphere inside the chamber
Implementation Method 3
a heating device disposed inside the chamber and configured to heat the substrate by irradiating light to the substrate
Implementation Method 4
The vacuum device and the gas supply device are configured to alternately operate for one or more cycles to create the vacuum atmosphere and the pressurizing atmosphere inside the chamber
Data Source
AI summary
A device for removing a void in an underfill material is described. The device includes a chamber configured to accept a substrate applied with an underfill material therein; a gas supply device connected to the chamber and configured to inject a heated gas into the chamber to create a heating atmosphere and a pressurizing atmosphere inside the chamber; and a vacuum device connected to the chamber and configured to exhaust a gas to the outside of the chamber to create a vacuum atmosphere inside the chamber. The vacuum device and the gas supply device are configured to alternately operate once during each cycle of one or more cycles to create the vacuum atmosphere and the pressurizing atmosphere inside the chamber, and during each cycle of the one or more cycles, the vacuum device and the gas supply device are configured to alternately operate once. Related methods are also described.