Semiconductor Lead Bonding by Laser Welding Without Ultrasonic Damage
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Solution Overview
Problem
The reliability of semiconductor devices is compromised due to damage caused by ultrasonic bonding, which applies pressure and vibrations that can harm the semiconductor element during the bonding process of the strap to the source electrode.
Innovation Solution
A semiconductor device and bonding method that utilize laser welding with two laser beams of different wavelengths to bond a connecting member to the electrode member, avoiding the use of ultrasonic bonding and thereby reducing the risk of damage to the semiconductor element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ultrasonic bonding is used to join the strap to the source electrode, then electrical connection is ensured, but the semiconductor element may be damaged due to pressure and vibrations
Solution Approach 1:
The patent replaces the mechanical ultrasonic bonding system with a laser welding system. Instead of using mechanical pressure and ultrasonic vibrations to join the strap to the source electrode, the invention uses laser energy to melt and fuse the materials together, thereby eliminating the harmful mechanical effects on the semiconductor element while maintaining reliable electrical connection
Solution Approach 2:
The patent changes the bonding parameters from mechanical (pressure, vibration frequency) to optical/thermal (laser wavelength, power, pulse duration). By using specific laser parameters such as wavelength selection and pulse control, the bonding process achieves reliable electrical connection without subjecting the semiconductor element to damaging mechanical stress
2Object-affected harmful factors
If laser welding is used to bond the connecting member to the electrode member, then damage from pressure and vibrations is avoided, but the bonding process complexity increases due to use of two laser beams
Solution Approach 1:
The patent divides the bonding process into two sequential stages using two different laser beams: first laser beam for initial bonding and second laser beam for reinforcement or finishing. This segmentation allows each laser to be optimized for its specific function, achieving effective bonding while managing process complexity through structured multi-step approach
Solution Approach 2:
The patent employs two laser beams with different wavelengths that can be selectively applied based on material properties and bonding requirements. This multi-functional approach allows the same laser welding system to handle different material combinations and bonding conditions, reducing overall process complexity despite using multiple beams
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 approach enhances the reliability of the semiconductor device by preventing damage from pressure and vibrations, ensuring a more robust electrical connection without compromising the integrity of the semiconductor element.
Implementation Method 1
bonding the connecting member to the electrode member by laser welding
Implementation Method 2
The ultrasonic bonding involves pressing the strap against the source electrode and applying ultrasonic vibrations
Data Source
AI summary
Semiconductor device A1 of the disclosure includes: semiconductor element 11 having element obverse surface 11a and element reverse surface 11b spaced apart from each other in z direction (first direction) with first region 111 formed on the element obverse surface 11a; metal plate 31 (electrode member) disposed on the element obverse surface 11a and electrically connected to the first region 111; electrically conductive substrate 22A (first conductive member) disposed to face the element reverse surface 11b and bonded to the semiconductor element 11; electrically conductive substrate 22B (second conductive member) spaced apart from the conductive substrate 22A (first conductive member); and lead member 5 (connecting member) electrically connecting the metal plate 31 (electrode member) and the conductive substrate 22B (second conductive member). The lead member 5 (connecting member) is bonded to the metal plate 31 (electrode member) by laser welding. The semiconductor device of this configuration provides improved reliability.