Ultrasonic Standing Wave Apparatus for Bonding Stage Turbulence
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Solution Overview
Problem
Existing bonding apparatuses face challenges in maintaining accurate image position detection due to air turbulence caused by temperature differences, which can be exacerbated by the use of nitrogen gas or air to clear turbulence, and may negatively impact bonding quality, especially in wire bonding processes where ultrasonic discharge forms a free-air ball.
Innovation Solution
A mounting apparatus that incorporates an ultrasonic standing wave generating device, comprising an ultrasonic speaker and a reflection surface, such as a flat plate, to create a standing wave in the space between the mounting stage and the imaging device, effectively reducing air turbulence and improving image position detection accuracy without the need for extensive gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If nitrogen gas or air is blown into the field of view to clear air turbulence, then image position detection accuracy is improved, but large amounts of nitrogen gas are required and bonding quality deteriorates due to temperature decrease
Solution Approach 1:
The patent replaces the pneumatic system (blowing nitrogen gas or air) with an ultrasonic standing wave generation system. The ultrasonic speaker generates ultrasonic waves that form a standing wave pattern, creating a virtual wall effect that prevents air turbulence from entering the imaging field of view, thereby eliminating the need for large amounts of nitrogen gas while maintaining detection accuracy
Solution Approach 2:
The patent changes the physical state and parameters of the ultrasonic waves by adjusting frequency and amplitude to create a standing wave pattern with specific node and antinode positions. This parameter control allows the ultrasonic waves to form an effective barrier against air turbulence without requiring gas flow, solving both the gas consumption and temperature maintenance problems
2Measurement precision
If nitrogen gas or air is blown into the field of view to clear air turbulence, then image position detection accuracy is improved, but bonding quality deteriorates due to free-air ball temperature decrease
Solution Approach 1:
The patent replaces the pneumatic clearing method with ultrasonic standing wave generation. The ultrasonic waves create a pressure node barrier that physically prevents air turbulence from reaching the imaging field and the free-air ball, thereby maintaining both detection accuracy and bonding quality without the harmful cooling effect of gas flow
Solution Approach 2:
The ultrasonic standing wave acts as an intermediary barrier between the heat source (bonding stage and free-air ball) and the cold air turbulence. The standing wave pattern, particularly the pressure nodes, creates a virtual wall that mediates the interaction between hot and cold air, preventing direct contact and heat loss while allowing optical imaging to proceed
3Temperature
If the bonding stage is heated to 200 degrees C for bonding, then bonding process is enabled, but air turbulence is generated over the bonding stage
Solution Approach 1:
The patent employs periodic ultrasonic vibrations at high frequency to generate standing waves. This periodic action creates stable pressure nodes and antinodes that form a consistent barrier against the thermal convection currents, allowing the bonding stage to maintain high temperature for bonding while preventing air turbulence from reaching the imaging field
Solution Approach 2:
The ultrasonic speaker generates mechanical vibrations in the form of ultrasonic waves that propagate through the air above the bonding stage. These vibrations create a standing wave pattern with pressure nodes that act as barriers to air flow, suppressing the harmful air turbulence caused by thermal convection while allowing the bonding process to proceed at required temperatures
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 implementation of the ultrasonic standing wave apparatus enhances the accuracy of image position detection and maintains bonding quality by minimizing air turbulence and temperature-induced fluctuations, thereby improving the overall precision and reliability of the bonding process.
Implementation Method 1
an ultrasonic standing wave generation device that generates an ultrasonic standing wave in a space between the upper surface of the mounting stage and the imaging device
Implementation Method 2
generating an ultrasonic standing wave in the space between the upper surface of the mounting stage and the imaging device
Implementation Method 3
a substrate sucked and fixed to a bonding stage or a semiconductor die mounted on a substrate is heated up to about 200 to 250 degrees C.
Implementation Method 4
the air over the bonding stage is heated by the bonding stage to move upward. The surrounding cold air then comes over the bonding stage and is heated by the bonding stage to move upward again, causing a circulation of air. Upon this, airs of different temperatures, that is, different densities due to rising air are mixed to cause air turbulence over the bonding stage.
Data Source
AI summary
Provided is a bonding apparatus including a bonding stage 83 for heating a substrate (lead frame) 61 placed on the upper surface thereof or a semiconductor die 63 mounted on the substrate (lead frame) 61, an imaging device 20 arranged above the bonding stage 83 to image the substrate 61 placed on the bonding stage 83 or the semiconductor die 63 mounted on the substrate 61, and a standing wave generating device 35 for generating an ultrasonic standing wave in the space between the upper surface of the bonding stage 83 and the imaging device 20. This improves the accuracy of image position detection by the imaging device with a simple structure.