Wire Shape Inspection Using Reflected Light
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Solution Overview
Problem
Conventional wire shape inspection methods, such as the focus method, are unable to detect the shape of the neck portion of a wire bonded between a semiconductor chip and a mounted body, as it is hidden by the lateral portion and cannot be observed directly by the camera.
Innovation Solution
A wire shape inspecting apparatus and method that uses a camera and light sources to capture images of the wire from a first direction, identifying the position of the wire using reflected light, allowing detection of the shape even in areas not visually recognizable, including the neck portion, through specific processing techniques and light source configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the focus method is used to detect wire shape, then the observable lateral portion can be detected, but the neck portion hidden on the back side cannot be detected
Solution Approach 1:
The patent introduces a new detection dimension by capturing reflected light from the wire surface. Instead of relying solely on direct optical observation from above, the system detects light reflected from the wire's lateral surface, which carries information about the hidden neck portion's shape and position. This dimensional shift in detection approach enables observation of previously invisible regions.
Solution Approach 2:
The patent uses reflected light as an intermediary to indirectly detect the neck portion's shape. Since the neck portion is hidden and cannot be observed directly, the system captures light reflected from the wire's lateral surface, which serves as a mediator carrying information about the hidden portion's geometry. This indirect detection method resolves the contradiction between direct observation limitations and complete shape detection requirements.
2Area of stationary object
If multiple images are captured while changing focal distance, then the observable area coverage increases, but the detection completeness of hidden portions remains insufficient
Solution Approach 1:
The patent utilizes changes in light reflection characteristics (analogous to color changes) as the focal distance varies. By capturing images at multiple focal distances, the system observes how reflected light from different wire portions appears and disappears from the image, allowing identification of the neck portion's position and shape through these dynamic reflection pattern changes.
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 reliable detection of the wire shape, including the neck portion, by utilizing reflected light to identify the position of the wire, thereby improving the precision and completeness of the inspection.
Implementation Method 1
a light emitting portion which is an image part of reflected light where light from the light is reflected by the wire is identified in the inspection image
Data Source
AI summary
This wire shape inspecting apparatus comprises a camera which captures an image of a wire from above, a light which illuminates the wire from above, and a control unit, wherein the control unit performs: an inspection image acquiring process of acquiring a plurality of inspection images by causing the camera to capture images of the wire a plurality of times while changing a focal distance; and a first shape detecting process of identifying, in each inspection image, a light emitting portion, which is an image part including reflected light comprising light from the light that has been reflected by the wire, and identifying an actual light emitting portion position, which is the actual position of the light emitting portion, on the basis of the position of the light emitting portion in the inspection image and the focal distance when the inspection image was acquired.