Comprehensive Analysis of Misjudgment Factors in Scanning Acoustic Microscopy (SAT & SAM)

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Ultrasonic scanning (including SAT and C-SAM technologies), as a non-destructive testing method, has been widely used in the quality inspection of integrated circuit a……

Ultrasonic scanning (including SAT and C-SAM technologies), as a non-destructive testing method, has been widely used in the quality inspection of integrated circuit and discrete device packaging due to its advantages of high sensitivity, high resolution, and real-time imaging. However, ensuring the reliability of the test results must be based on strict procedural standards. From a professional perspective, it is necessary to identify and avoid numerous factors that may lead to misjudgment. A lack of understanding of these factors can significantly increase the risks of imaging distortion and defect omission. Misjudgments in ultrasonic scanning are mainly influenced by material types, defect categories, equipment conditions, and operational subjectivity. The following sections will elaborate on these factors in detail.

Analysis of Comprehensive Factors Related to Packaging, Defect Types, and Delamination “Composite” Phenomena

Surface Wave Loss Caused by Uneven Surfaces: Uneven surfaces on integrated circuits and discrete devices can cause scattering and refraction of ultrasonic waves during propagation, directly affecting the accuracy and reliability of test results.

Lead Frame Echo Loss: As one of the key components of integrated circuits, the echo from the lead frame is crucial for ultrasonic scanning results. If the echo signal weakens or disappears, it may lead to deviations or misjudgments in the test results.

False Waveforms: External interference or internal circuit defects can generate false waveforms during ultrasonic scanning. These waveforms may be confused with actual defect signals, thereby affecting the accuracy of the test results.

Void at Chip Edge: Voids located at the edges of integrated circuit chips can affect the propagation path and scattering pattern of ultrasonic waves, negatively impacting the accuracy and reliability of the test results.

Delamination Phenomenon: During manufacturing and usage, integrated circuits and discrete devices may experience delamination, which can cause attenuation or refraction of ultrasonic waves during propagation, reducing the accuracy and reliability of test results.

Delamination “Composite” Phenomenon: It is common practice to use ultrasonic scanning to eliminate products with delamination defects to improve quality. However, after multiple scans in coupling liquid (e.g., deionized water), the delamination phenomenon may change as soaking time increases, either gradually disappearing or worsening.

Excessive Mold Compound Thickness: For integrated circuits and discrete devices with thick mold compounds, it is difficult for ultrasonic scanning microscopes to detect small defects. The imaging effect depends on the detection depth and sensor frequency: the greater the depth, the more significant the signal attenuation; the higher the frequency, the greater the attenuation at the same depth.

Equipment Factors

The key components of ultrasonic scanning equipment, including the ultrasonic generator, probe, and receiver, directly determine the accuracy of the test results based on their performance and condition.

Equipment Aging: Over time, electronic components and probe crystals in the equipment may experience wear or performance degradation. This aging can lead to a decline in the stability and clarity of ultrasonic signals, increasing the risk of misjudgment.

Improper Maintenance: As a core component of ultrasonic scanning equipment, the probe requires regular calibration and cleaning to maintain optimal performance. If the probe surface becomes contaminated or damaged, or if the internal components of the equipment are not properly maintained, image quality will deteriorate, leading to misjudgments.

Unreasonable Parameter Settings: Ultrasonic scanning equipment offers various adjustable parameters, such as gain, frequency, and depth. These settings are critical to the test results. If the parameters are improperly configured, the signal may become either too strong or too weak, failing to accurately reflect the true condition of the object being tested, ultimately resulting in misjudgment.

Environmental Factors

1.The conditions of the testing environment have a significant impact on ultrasonic scanning results. The following points are particularly important:

2. Temperature and Humidity: Changes in environmental temperature and humidity can affect the propagation speed and attenuation of ultrasonic waves, leading to variations in ultrasonic images. Conducting tests in environments with significant fluctuations in temperature and humidity may reduce the stability of ultrasonic scanning results, affecting the accuracy and reliability of the final test outcomes.

3. Noise Interference: Sources of interference such as electromagnetic noise and mechanical vibrations in the environment can disrupt ultrasonic scanning equipment, causing distortion or deviation in ultrasonic signals and increasing the risk of misjudgment. Therefore, ensuring a relatively quiet and stable testing environment is crucial for obtaining high-quality ultrasonic scanning results.

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Comprehensive Analysis of Misjudgment Factors in Scanning Acoustic Microscopy (SAT & SAM)

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Comprehensive Analysis of Misjudgment Factors in Scanning Acoustic Microscopy (SAT & SAM)

Analysis of Comprehensive Factors Related to Packaging, Defect Types, and Delamination “Composite” Phenomena

Surface Wave Loss Caused by Uneven Surfaces: Uneven surfaces on integrated circuits and discrete devices can cause scattering and refraction of ultrasonic waves during propagation, directly affecting the accuracy and reliability of test results.

Lead Frame Echo Loss: As one of the key components of integrated circuits, the echo from the lead frame is crucial for ultrasonic scanning results. If the echo signal weakens or disappears, it may lead to deviations or misjudgments in the test results.

False Waveforms: External interference or internal circuit defects can generate false waveforms during ultrasonic scanning. These waveforms may be confused with actual defect signals, thereby affecting the accuracy of the test results.

Void at Chip Edge: Voids located at the edges of integrated circuit chips can affect the propagation path and scattering pattern of ultrasonic waves, negatively impacting the accuracy and reliability of the test results.

Delamination Phenomenon: During manufacturing and usage, integrated circuits and discrete devices may experience delamination, which can cause attenuation or refraction of ultrasonic waves during propagation, reducing the accuracy and reliability of test results.