Capillary Vibration Measurement Using Split Beam Reference
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Solution Overview
Problem
Existing devices for measuring the vibration amplitude of capillaries in wire bonders suffer from limited accuracy due to temperature fluctuations and high noise levels, leading to inconsistent bond quality.
Innovation Solution
A device that splits the light beam into a measuring beam and a reference beam, with the capillary partially shading the measuring beam while the reference beam remains unshaded, using imaging optics and detectors to generate a differential signal that is amplified, reducing noise and maintaining accuracy across temperature fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light barrier measurement device is used to measure capillary vibration amplitude, then the measurement function is provided, but temperature fluctuations cause light output changes that reduce measurement accuracy
Solution Approach 1:
The patent introduces a reference beam as an intermediary element that does not pass through the capillary but travels through the same optical path as the measuring beam. This reference beam serves as a mediator to compensate for temperature-induced light output changes by providing a baseline signal that can be used to normalize the measuring beam signal, thereby maintaining measurement accuracy despite temperature fluctuations.
Solution Approach 2:
The patent implements a feedback mechanism where the reference beam signal is continuously monitored and used to adjust or compensate for changes in the measuring beam signal caused by temperature variations. The system uses the reference signal to calculate compensation factors that are applied to the measurement signal, creating a closed-loop feedback system that maintains measurement precision under varying temperature conditions.
2Device complexity
If a single beam is used for measurement, then the device complexity is reduced, but the measurement accuracy is compromised due to temperature-induced light output variations
Solution Approach 1:
The patent segments the single light beam into two separate beams: a measuring beam that passes through the capillary and a reference beam that does not. This segmentation allows the system to separate the measurement function (detecting capillary vibrations) from the reference function (monitoring temperature-induced light output changes), enabling accurate measurements while maintaining relatively simple device architecture.
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 device provides low-noise, error-free measurement of capillary vibration amplitude, allowing for precise determination of both fundamental and harmonic vibrations, even under temperature changes, thereby enhancing bond quality reproducibility.
Implementation Method 1
The capillary is placed between a light source and a detector arrangement. The vibration amplitude can be determined from the shadowing of a beam of rays by the capillary.
Implementation Method 2
A piezo actuator A generates an axial ultrasonic wave with a frequency of approx. 100 kHz in the wire bonder.
Implementation Method 3
Devices are known for measuring the oscillation amplitude of capillaries of a wire bonder, in which the capillary is placed between a light source and a detector arrangement.
Data Source
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AI summary
The invention relates to a device for measuring the vibration amplitude of a capillary of a wire bonder. The capillary is placed between a light source and a detector assembly such that the vibration amplitude can be determined from the blocking of a beam by the capillary. The beam emitted by the light source is split into a measurement beam and a reference beam. In the vibrating state, an edge of the capillary at least partially blocks the measurement beam, while the reference beam is not blocked. The detector assembly comprises a measurement detector associated with the measurement beam and at least one reference detector associated with the reference beam. The vibration amplitude of the capillary can be determined from the output signals of the measurement detector and of the reference detector, which output signals are connected to each other.