Fine Diameter Wire Bonding Acceptance Using Thermal Field Measurement
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Solution Overview
Problem
Conventional methods for determining the acceptance/rejection of fine diameter wire bonding in electronic components face issues with uniformity in quality, reliability, and high costs, and are unable to accurately evaluate the bonding state using image inspection methods.
Innovation Solution
A method and apparatus that measure the heat conducted between bonding members using a two-wavelength infrared thermometer to determine the bonding area, allowing for high-speed temperature measurement with emissivity correction, and comparing the results to acceptable criteria for accurate acceptance/rejection determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If visual inspection or image processing methods are used to determine acceptance/rejection of wire bonding, then automation can be achieved, but the bonding state cannot be accurately evaluated
Solution Approach 1:
The patent replaces visual inspection methods with a thermal field-based measurement system. A laser heater heats the bonding portion, and an infrared thermometer measures the temperature distribution. This thermal field measurement substitutes for optical field-based visual inspection, enabling accurate evaluation of the bonding state through temperature characteristics rather than appearance geometry.
Solution Approach 2:
The patent changes the measurement parameter from geometric appearance (visual inspection) to thermal characteristics (temperature distribution). By measuring how temperature distributes and conducts through the bonding portion, the system can accurately evaluate bonding quality. The temperature change rate and distribution patterns serve as new parameters that directly reflect bonding state.
2Measurement precision
If X-ray radiographic test is used to directly observe the bonding portion, then the bonding state can be evaluated, but higher resolving power is required
Solution Approach 1:
The patent substitutes X-ray radiographic testing with infrared thermal measurement. Instead of using electromagnetic radiation in the X-ray range to image the bonding portion, the system uses infrared radiation to measure temperature distribution. This replacement eliminates the need for high resolving power while maintaining the ability to evaluate bonding state, as thermal characteristics provide direct information about bonding quality.
3Measurement precision
If emissivity variation due to surface conditions is considered in infrared measurement, then measurement accuracy is affected, but correction complexity increases
Solution Approach 1:
The patent creates a reference temperature distribution pattern from a known good bonding portion. This reference pattern is stored and used for comparison with actual measurements. By comparing the measured temperature distribution against the reference, the system can evaluate bonding quality without needing to explicitly correct for emissivity variations, as the comparison inherently accounts for surface condition differences.
Solution Approach 2:
The patent shifts from absolute temperature measurement (which requires emissivity correction) to relative temperature distribution comparison. By measuring temperature changes relative to a reference pattern and evaluating the temperature change rate, the system eliminates the need for absolute emissivity values. The evaluation is based on how the temperature distribution evolves over time rather than absolute temperature values.
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 provides high evaluation reliability and low-cost determination of fine diameter wire bonding, unaffected by surface conditions, improving the accuracy and reliability of bonding assessments in semiconductors and LEDs.
Implementation Method 1
performing a temperature measurement at high speed with correction of the emissivity on the basis of a minute amount of infrared rays radiated from a heated portion
Implementation Method 2
heating the bonding portion of a fine diameter wire with a laser device of a fine spot diameter
Implementation Method 3
the quantity of heat conducted is in proportion to the bonding density and the bonding area between the bonding members
Data Source
Figure 1
Figure 2(A)~2(B)
Figure 3~4
AI summary
Disclosed are a method and an appartus for determining acceptance/rejection of fine diameter wire bonding of semiconductor devices, LED devices, and the like at a high accuracy without contact, said acceptance/rejection having not been determined by conventional image inspecting methods and the like. The appartus is configured of a heating laser device (1) which spot-heats the bonding portion of the fine diameter wire; a two-wavelength infrared radiation thermometer (2), which corrects an emissivity and measures a temperature at a high speed on the basis of a minute amount of infrared rays radiated from the heated portion of the fine diameter wire; and a correcting/determining means (4), which corrects the measurement results obtained from the two-wavelenght infrared radiation thermometer (2) to a temperature change with reference heating power, then determines acceptance/rejection of the bonding by comparing the corrected temperature change or a value correlated to a bonding area obtained on the basis of the corrected temperature change with a temperature change indicated by an acceptable reference product having the temperature change corrected with the reference heating power or a value correlated to a bonding area obtained on the basis of the temperature change indicated bye the acceptable reference product.