Microwave Solder Bump Reflow to Limit Warpage and Voids
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Solution Overview
Problem
The formation of solder bumps through thermal convection heating in semiconductor devices leads to warpage issues due to mismatch in thermal expansion coefficients, affecting device performance and fabrication processes.
Innovation Solution
A method involving microwave radiation to reflow solder paste with simultaneous vacuum pressure application to remove voids, ensuring uniform heating and void removal, resulting in solder bumps with reduced defects and improved joint reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal convection heating is applied to reflow solder paste, then solder bumps are formed for electrical connection, but warpage issues occur due to CTE mismatch between materials
Solution Approach 1:
The patent replaces thermal convection heating with microwave radiation heating to reflow solder paste. Microwave radiation directly heats the solder paste through dielectric heating, eliminating the need for uniform thermal convection across the entire substrate. This substitution resolves the warpage issue caused by CTE mismatch while maintaining effective solder reflow and electrical connection reliability.
Solution Approach 2:
The patent changes the heating parameter from thermal convection (bulk heating) to microwave radiation (direct electromagnetic heating). This parameter change allows selective heating of the solder paste without uniformly heating the entire substrate and component assembly, thereby preventing warpage while achieving proper solder reflow.
2Reliability
If thermal convection heating is used to reflow solder paste, then solder bumps are formed, but voids are trapped within the solder paste affecting joint quality
Solution Approach 1:
The patent replaces thermal convection heating with microwave radiation heating, which provides more uniform and penetrative heating throughout the solder paste. This eliminates temperature gradients that cause premature solidification and void trapping, resulting in more uniform solder bumps with fewer voids and improved joint reliability.
Solution Approach 2:
The patent utilizes controlled phase transition of solder paste from solid to liquid and back to solid through microwave heating. The rapid and uniform heating ensures complete melting without localized overheating, and the subsequent controlled cooling allows proper void elimination during the liquid phase before solidification, resulting in high-quality solder joints.
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 method reduces warpage and enhances the reliability of electrical joints by forming uniform solder bumps with fewer defects, improving the overall performance and efficiency of semiconductor devices.
Implementation Method 1
applying microwave radiation to the substrate to reflow the solder paste
Implementation Method 2
applying a vacuum pressure to the substrate to remove voids formed within the solder paste during the reflowing of the solder paste
Data Source
AI summary
A method and an apparatus for forming an electronic device is provided. The method comprises: providing a substrate; disposing at least one electronic component on the substrate via a solder paste; applying microwave radiation to the substrate to reflow the solder paste; applying a vacuum pressure to the substrate to remove voids formed within the solder paste during the reflowing of the solder paste; solidifying the solder paste into solder bumps between the substrate and the at least one electronic component.