Ultrasonic Bonding Load Sensor for Mid-Bond Pass/Fail Detection
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Solution Overview
Problem
Existing wire-bonding apparatuses face challenges in detecting defective bonding in real-time during the process, leading to potential chip damage and reduced production yield due to fluctuations in pressing load and mechanical issues, which current methods fail to address before visual inspection.
Innovation Solution
A bonding apparatus with a load sensor and low-pass filter system that continuously detects load changes and determines pass/fail bonding based on impact load, allowing for mid-bonding detection of abnormal ball deformation and chip damage by filtering out resonant frequency signals and analyzing the extracted signal for maximum load values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an encoder is provided in the bonding head to detect the change in the height position of the capillary, then the pressing load fluctuation can be partially controlled through feedback, but the pressing load cannot be suppressed sufficiently because the encoder cannot detect the pressing load on the wire directly
Solution Approach 1:
The patent replaces the mechanical encoder-based detection system with an optical interferometry system. The interferometer uses light interference patterns to directly measure the pressing load on the wire, providing more accurate and direct measurement compared to the indirect mechanical encoder method. This substitution enables sufficient suppression of pressing load fluctuation by providing precise real-time load data for feedback control.
2Reliability
If an impact sensor is attached to the bonding stage to measure the force of impact, then mechanical loosening or wear can be detected, but defective bonding such as abnormal ball deformation and chip damage cannot be detected during the bonding operation before visual inspection
Solution Approach 1:
The patent implements real-time feedback control by continuously monitoring the pressing load during bonding operation using the interferometer. The measured load data is immediately fed back to the control system, which can detect abnormal ball deformation and chip damage as they occur, rather than waiting for post-bonding visual inspection. This enables immediate detection and correction of defective bonding, significantly reducing product revision time.
3Productivity
If multiple pads on the semiconductor chip are connected sequentially to multiple leads on the substrate, then complete bonding can be achieved, but defective bonding cannot be detected before the final visual inspection step, resulting in reduced production yield
Solution Approach 1:
The patent maintains continuous monitoring of the pressing load throughout the entire sequential bonding process. The interferometer continuously measures the load on the wire as each pad is bonded to its corresponding lead, enabling real-time detection of defective bonding. This continuous measurement approach ensures that no bonding defects go undetected during the sequential bonding operation, improving production yield by allowing immediate identification and correction of defects.
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
Enables immediate detection of defective bonding during the process, preventing further damage and improving production yield by allowing for real-time intervention and reducing the need for extensive visual inspection.
Implementation Method 1
an ultrasonic vibrator attached to the ultrasonic horn... the ultrasonic horn is resonated by the ultrasonic vibrator to provide ultrasonic vibration at the tip end of the capillary for bonding operation
Implementation Method 2
an ultrasonic horn configured to vibrate longitudinally in resonance with the vibration of an ultrasonic vibrator
Implementation Method 3
a load sensor attached between the center of rotation of the bonding arm and the flange mounting surface... continuously detecting a load on the bonding tool... defining the maximum value of the detected load as an impact load
Data Source
AI summary
An apparatus for pass/fail determination of bonding used in a bonding apparatus, includes: an ultrasonic horn configured to vibrate longitudinally in resonance with the vibration of an ultrasonic vibrator; a capillary attached at an anti-node of the vibration of the ultrasonic horn; a flange provided at a node of the vibration of the ultrasonic horn; a bonding arm; and a load sensor attached between the center of rotation of the bonding arm and a flange mounting surface in an offset manner from a longitudinal central axis of the ultrasonic horn, in which a load on the capillary in the direction toward and away from the bonding target is continuously detected by using the load sensor during bonding operation and the maximum value of the detected load is defined as an impact load to determine pass/fail of the bonding based on the impact load, thereby allowing a mid-bonding pass/fail determination.