Microwave Solder Reflow for Low-Warpage Semiconductor Packaging
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Solution Overview
Problem
Semiconductor devices face challenges in manufacturing as they become smaller, leading to increased susceptibility to warpage during the manufacturing process, which traditional packaging techniques struggle to control effectively.
Innovation Solution
The use of microwave soldering for reflowing solder bumps, which applies volumetric heating to minimize substrate warpage by selectively heating polar materials like flux and solder without significantly heating the substrate, allowing for more precise heat control and reduced warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional packaging techniques are used for smaller semiconductor devices, then manufacturing complexity increases, but warpage control deteriorates
Solution Approach 1:
The patent replaces traditional mechanical/conductive heating systems with microwave electromagnetic radiation for heating. This substitution enables volumetric heating of solder and flux without significantly heating the substrate, thereby reducing thermal stress and warpage while maintaining effective solder reflow for complex packaging structures
Solution Approach 2:
The patent changes the heating parameter from conventional conductive/convective heat transfer to microwave electromagnetic radiation. This parameter change enables selective heating of polar materials (solder, flux) based on their dielectric properties, achieving precise thermal control that minimizes substrate warpage while enabling advanced packaging techniques
2Volume of moving object
If smaller semiconductor devices are manufactured, then device size decreases, but susceptibility to warpage increases
Solution Approach 1:
The patent replaces traditional heating methods with microwave radiation to achieve volumetric heating that is selective to solder and flux materials. This substitution reduces overall thermal exposure to the substrate, minimizing thermal expansion and warpage in smaller device structures
Solution Approach 2:
The patent applies local quality by selectively heating only the polar materials (solder and flux) that require thermal processing, while leaving the substrate relatively cool. This localized heating approach prevents uniform thermal expansion that causes warpage in miniaturized devices
3Manufacturing precision
If conventional heating methods are used for solder reflow, then heating uniformity is insufficient, but energy consumption increases
Solution Approach 1:
The patent substitutes conventional conductive/convective heating with microwave electromagnetic radiation. This enables direct volumetric heating of the solder and flux throughout their volume simultaneously, achieving superior heating uniformity while reducing the total energy required compared to heating entire substrates or using prolonged conventional heating cycles
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
Microwave soldering enables the production of smaller and more complex semiconductor packages with reduced warpage, facilitating faster and more uniform heating, thereby enabling package-on-package or system-in-package structures and reducing manufacturing costs.
Implementation Method 1
applies volumetric heating to minimize substrate warpage by selectively heating polar materials like flux and solder without significantly heating the substrate
Implementation Method 2
The use of microwave soldering for reflowing solder bumps, which applies volumetric heating to minimize substrate warpage
Data Source
AI summary
A semiconductor device has a semiconductor package and a flux disposed on the semiconductor package. A solder ball is disposed on the flux. The solder ball is reflowed using microwave energy. The microwave energy is applied until a temperature of the flux reaches between 200 and 220° C. The flux and solder ball both include polarized molecules. The substrate is devoid of polarized molecules.