Laser Soldering with Dual-Side Preheating to Reduce Substrate Warpage
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Solution Overview
Problem
Existing soldering methods in semiconductor and PCB manufacturing, such as Mass Reflow, result in prolonged processing times and increased risk of thermal deformation and warpage due to differences in thermal expansion coefficients between chips and substrates, leading to defects from uneven soldering temperatures.
Innovation Solution
A laser-based soldering method that preheats both upper and lower substrate portions simultaneously before laser irradiation, using a substrate fixing member with vacuum adsorption and masks to control heat distribution and prevent edge damage, allowing for rapid solder attachment and reduced process time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Mass Reflow or IR lamp heating is used to melt and solidify solder, then electrical connection between substrate and solder is achieved, but processing time is prolonged and thermal deformation and warpage occur
Solution Approach 1:
The patent replaces conventional thermal field methods (Mass Reflow, IR lamp) with a laser beam for localized heating. The laser irradiation system substitutes the broad thermal field with a focused energy source that can rapidly melt solder only at the required positions, significantly reducing processing time while maintaining solder attachment quality.
Solution Approach 2:
The patent applies heating locally only to the solder regions requiring attachment, rather than heating the entire substrate uniformly. The laser beam is directed to irradiate specific solder positions, creating localized melting zones that reduce overall thermal exposure and processing time while ensuring proper solder bonding.
2Manufacturing precision
If high temperature is applied to entire substrate for solder melting, then solder attachment is achieved, but warpage occurs due to difference in coefficient of thermal expansion between chip and substrate
Solution Approach 1:
The patent applies heating locally only to the solder regions requiring attachment, rather than heating the entire substrate uniformly. The laser beam is directed to irradiate specific solder positions, creating localized melting zones that reduce overall thermal exposure and processing time while ensuring proper solder bonding.
Solution Approach 2:
The patent divides the heating process into discrete localized zones using laser irradiation. Each solder joint is treated as a separate heating zone, allowing independent temperature control and minimizing thermal stress on the overall substrate structure, thereby preventing warpage.
3Manufacturing precision
If conventional heating methods are used, then solder melting is achieved, but uneven solder processing temperature causes defects
Solution Approach 1:
The patent replaces conventional thermal field methods (Mass Reflow, IR lamp) with a laser beam for localized heating. The laser irradiation system substitutes the broad thermal field with a focused energy source that can rapidly melt solder only at the required positions, significantly reducing processing time while maintaining solder attachment quality.
Solution Approach 2:
The patent incorporates a temperature detection unit that monitors the temperature of the substrate and solder in real-time during laser irradiation. This feedback mechanism allows the system to adjust laser power dynamically, ensuring uniform solder processing temperature and preventing defects caused by overheating or insufficient heating.
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 significantly reduces warpage, thermal shock, and processing time, while preventing defects caused by uneven soldering temperatures by ensuring uniform heat transfer and precise laser application.
Implementation Method 1
an attachment process in which the upper portion of the substrate is irradiated with the laser so that the solder is melted and attached to the upper portion of the substrate
Implementation Method 2
a substrate fixing member with vacuum adsorption
Data Source
AI summary
Proposed is a solder soldering method using a laser. The solder soldering method performs solder soldering within a few seconds by using the laser so that warpage occurring due to a difference in a coefficient of thermal expansion between a chip and a substrate may be reduced, thermal shock that occurs on the chip and the substrate may be reduced, an entire process time may be reduced, and defects due to an uneven solder processing temperature may be reduced. The solder soldering method includes a supplying process in which a substrate having solder is supplied to a substrate fixing member, a preheating process in which the substrate and the solder are preheated, an attachment process in which the substrate is irradiated with the laser and the solder is melted and attached to the substrate, and a discharging process in which the substrate is moved to a tray.