An automated inspection system for semiconductor package wire bond quality

Abstract

This invention discloses an automated inspection system for semiconductor packaging wire bonding quality, relating to the field of semiconductor packaging technology. It includes: a multi-frequency signal transmitting module for sequentially transmitting high-frequency, mid-frequency, and low-frequency electrical signals to the wire bonding; a receiving module for receiving the multi-frequency electrical signals transmitted by the wire bonding and acquiring the signal strength of each frequency band in real time; a thermal noise detection module for detecting the thermal noise level in the wire bonding; a time-domain reflectometry module for transmitting high-frequency pulse signals to the wire bonding, detecting the reflection time and waveform characteristics of the signals in the wire bonding, and identifying physical defects in the wire bonding; and a data analysis module for comprehensively analyzing the multi-frequency signal strength, thermal noise level, and time-domain reflectometry waveform characteristics after temperature compensation to determine the wire bonding quality. In the comprehensive data analysis, all detection data are integrated and analyzed to achieve comprehensive inspection of wire bonding quality, significantly improving the accuracy and reliability of the inspection.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging technology, and in particular to an automated inspection system for the quality of semiconductor packaging wire bonding. Background Technology

[0002] With the continuous development of semiconductor packaging technology, wire bonding, as a key connector between chips and external circuits, directly affects the reliability and performance of the package. Currently, wire bonding quality inspection technology mainly relies on signal transmission performance testing, wire bonding resistance monitoring, and physical structural defect identification. However, existing testing methods typically focus only on signal transmission in a single frequency band, such as detecting only high-frequency or low-frequency signals. This makes it difficult to comprehensively evaluate the transmission performance of wire bonding at different frequencies. Simultaneously, the impact of thermal noise and temperature changes on signal transmission has not been effectively compensated for, especially in high-speed and high-density packaging applications where the impact of temperature changes on wire bonding electrical performance is increasingly significant, and existing technologies often neglect the necessity of temperature compensation. Furthermore, while traditional time-domain reflectometry (TDR) technology can detect physical defects in wire bonding, its accuracy and reliability still need improvement in complex multi-frequency signal environments.

[0003] The shortcomings of existing technologies are mainly reflected in the following aspects: First, single-band signal detection cannot comprehensively evaluate the transmission performance of the wire bond at different frequency bands, resulting in limitations in the judgment of wire bond quality. Second, existing wire bond inspection systems fail to effectively consider the influence of temperature on signal strength and resistance, lacking a real-time temperature compensation mechanism, which easily leads to inaccurate signal strength measurement results. Finally, TDR technology has certain accuracy bottlenecks in wire bond defect identification, especially in the analysis of high-frequency signal reflection waveforms, where existing technologies struggle to effectively capture subtle waveform feature changes. Therefore, there is an urgent need for an automated inspection system that can integrate multi-frequency signal strength, thermal noise level, temperature compensation, and TDR detection to improve the accuracy and reliability of wire bond quality inspection. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides an automated inspection system for the quality of semiconductor packaging wire bonding, which solves the problems of incomplete detection of multi-frequency signal transmission performance of wire bonding, lack of compensation for temperature changes, and insufficient accuracy of time-domain reflectometry detection in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides an automated inspection system for the quality of bonding wires in semiconductor packaging, comprising a multi-frequency signal transmission module for sequentially transmitting high-frequency, medium-frequency and low-frequency electrical signals to the bonding wires;

[0008] The receiving module is used to receive multi-frequency electrical signals transmitted by the bonding wire and to collect the signal strength of each frequency band in real time.

[0009] The temperature detection module is used to monitor the temperature changes of the bonding wire in real time and generate temperature data;

[0010] The temperature compensation module is used to perform temperature compensation on the received signal strength based on temperature data, and generate temperature-compensated signal strength data.

[0011] Thermal noise detection module, used to detect the thermal noise level in the wire bonding;

[0012] The time-domain reflectometry module is used to transmit high-frequency pulse signals to the bonding wire, detect the reflection time and waveform characteristics of the signal in the bonding wire, and identify physical defects in the bonding wire.

[0013] The data analysis module is used to comprehensively analyze the intensity of multi-frequency signals, thermal noise level, and time-domain reflection waveform characteristics after temperature compensation to determine the quality of wire bonding.

[0014] As a preferred embodiment of the automated inspection system for semiconductor packaging wire bonding quality described in this invention, the sequential transmission of high-frequency, medium-frequency, and low-frequency electrical signals to the wire bonding includes the following steps:

[0015] The frequency range of the signal source is set according to the characteristics of the bonding wire material and the sensitivity of the bonding wire's electrical performance, generating high-frequency, medium-frequency, and low-frequency signals;

[0016] Based on the physical characteristics of the signal and the electrical response speed of the bonding wire, high-frequency signals are preferentially emitted to quickly capture defects in surface and contact resistance;

[0017] After the high-frequency signal transmission is completed, it automatically switches to the medium-frequency signal mode for transmission to evaluate the surface effect and current distribution characteristics of the bonding wire;

[0018] After the intermediate frequency signal is transmitted, it automatically switches to the low frequency signal mode to transmit and detect the overall conductivity and capacitance effect of the bonding wire.

[0019] As a preferred embodiment of the automated inspection system for semiconductor packaging wire bonding quality described in this invention, the following steps are included: receiving multi-frequency electrical signals transmitted through the wire bonding and acquiring the signal strength of each frequency band in real time.

[0020] The receiver synchronously receives signals from various frequency bands and adjusts the signal levels of different frequency bands in real time through an automatic gain control mechanism.

[0021] The regulated signal is amplified by a low-noise amplifier, and a bandpass filter is used to suppress noise in the amplified signal.

[0022] After the signal is amplified and noise is suppressed, the receiver measures the signal power and phase for each frequency band to evaluate the signal transmission loss in the bonding wire.

[0023] The measured power and phase are converted from analog to digital by a data acquisition card, thus obtaining the signal strength of each frequency band.

[0024] As a preferred embodiment of the automated inspection system for semiconductor packaging wire bonding quality described in this invention, the real-time monitoring of wire bonding temperature changes and the generation of temperature data includes the following steps:

[0025] During the transmission and reception of multi-frequency signals, the temperature changes of the welding wire and its surrounding environment are continuously monitored, the temperature data of the welding point is obtained in real time, and a simulated temperature signal is generated.

[0026] The analog temperature signal is converted into a digital signal to generate temperature data;

[0027] The generated temperature data is synchronized with the signal strength of each frequency band and then stored.

[0028] As a preferred embodiment of the automated inspection system for semiconductor packaging wire bonding quality described in this invention, the process of generating temperature-compensated signal strength data by performing temperature compensation on the received signal strength based on temperature data includes the following steps:

[0029] Extract temperature data, and calculate the actual resistance at the current temperature based on the characteristics of the wire bonding material. The expression is as follows:

[0030] R(T) = R0[1 + α(T - T0)];

[0031] Where R(T) is the wire bonding resistance at the real-time wire bonding temperature T, R0 is the resistance at the reference temperature T0, α is the temperature coefficient of the wire bonding material, T is the real-time wire bonding temperature, and T0 is the reference temperature.

[0032] In a preferred embodiment of the automated inspection system for semiconductor packaging wire bonding quality described in this invention, the change in received signal power is calculated based on the change in resistance, expressed as:

[0033]

[0034] Where ΔP(T) is the change in power, G r It is the receiver gain.

[0035] As a preferred embodiment of the automated inspection system for semiconductor packaging wire bonding quality described in this invention, wherein: based on the received signal power and its variations, signal strength compensation is performed for each frequency band, expressed as:

[0036]

[0037] in, It is the compensated signal received power, P r This is the original signal received power.

[0038] As a preferred embodiment of the automated inspection system for semiconductor packaging wire bonding quality described in this invention, detecting the thermal noise level in the wire bonding includes the following steps:

[0039] Convert the generated temperature data points into absolute temperatures;

[0040] Based on the temperature and bandwidth of the bonding wire, the thermal noise power of each frequency band is calculated using the following expression:

[0041]

[0042] Where N is the thermal noise power, k B It is the Boltzmann constant, T C It is the converted absolute temperature, and Δf is the signal bandwidth;

[0043] Set thermal noise thresholds based on the material properties of the bonding wire, environmental conditions, and historical data;

[0044] The calculated thermal noise power for each frequency band is compared with the thermal noise threshold to determine whether there is any noise anomaly.

[0045] As a preferred embodiment of the automated inspection system for semiconductor packaging wire bonding quality described in this invention, the following steps are included: transmitting a high-frequency pulse signal to the wire bonding, detecting the reflection time and waveform characteristics of the signal in the wire bonding, and identifying physical defects in the wire bonding.

[0046] Start the time-domain reflectometer, send a high-frequency pulse signal to the starting point of the bonding wire, collect the reflected signal generated in the bonding wire in real time, and record the time difference between the reflected signal and the transmitted signal and the voltage change of the reflected waveform to generate waveform data;

[0047] The collected reflected waveforms are compared point by point with the standard waveforms in the historical database to analyze the differences in waveform amplitude, phase change and reflection time.

[0048] Based on the analysis results, the location of defects in the solder wire is determined, and the type of defect is identified.

[0049] As a preferred embodiment of the automated inspection system for semiconductor packaging wire bonding quality described in this invention, the method for determining wire bonding quality by comprehensively analyzing the intensity of multi-frequency signals after temperature compensation, thermal noise level, and time-domain reflection waveform characteristics includes the following steps.

[0050] The signal strength of each frequency band after temperature compensation is compared with the reference signal strength of that frequency band to evaluate the transmission performance of the bonding wire at different frequencies.

[0051] Compare the actual measured thermal noise power of each frequency band with the theoretical thermal noise power to determine whether the wire bonding resistance performance is normal.

[0052] Review the time-domain reflectance test results to confirm whether there are any abnormalities in the reflected waveform;

[0053] If the multi-frequency signal performs stably across all frequency bands during transmission, the thermal noise level is normal, and no abnormalities are detected by time-domain reflection detection, the wire bonding quality is deemed acceptable.

[0054] If any signal frequency band exhibits instability, excessive thermal noise, or defects detected in time-domain reflection, the wire bonding is deemed unqualified.

[0055] The beneficial effects of this invention are as follows: By introducing multi-frequency signal transmission and reception, high-frequency, mid-frequency, and low-frequency signals are transmitted sequentially to comprehensively evaluate the transmission performance of the bonding wire in different frequency bands, thus overcoming the shortcomings of existing technologies that only detect signals in a single frequency band. Simultaneously, by combining temperature detection and temperature compensation, the temperature changes of the bonding wire and its surrounding environment are monitored in real time. Based on the characteristics of the bonding wire material, temperature compensation is applied to the signal strength, effectively solving the problem of inaccurate signal strength measurement caused by environmental temperature fluctuations. Furthermore, thermal noise detection can detect the thermal noise level of the bonding wire, improving the accuracy of evaluating the bonding wire's resistance performance. Through time-domain reflection, physical defects in the bonding wire are detected, and combined with the characteristics of the reflected waveform, the defect location is accurately located, improving the detection accuracy of time-domain reflection technology. In comprehensive data analysis, all detection data are integrated and analyzed to achieve comprehensive detection of the bonding wire quality, significantly improving the accuracy and reliability of the detection. Attached Figure Description

[0056] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0057] Figure 1 This is a schematic diagram of an automated inspection system for semiconductor packaging wire bonding quality in Example 1.

[0058] Figure 2 This is a schematic diagram of multi-frequency signal transmission in Example 1. Detailed Implementation

[0059] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0060] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0061] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0062] Example 1, referring to Figure 1 and Figure 2 This is the first embodiment of the present invention, which provides an automated inspection system for the quality of semiconductor packaging bonding wires, comprising the following steps:

[0063] The process of sequentially transmitting high-frequency, medium-frequency, and low-frequency electrical signals to the bonding wire includes the following steps:

[0064] The frequency range of the signal source is set according to the characteristics of the bonding wire material and the sensitivity of the bonding wire's electrical performance, generating high-frequency, medium-frequency, and low-frequency signals. Based on the physical characteristics of the signal and the electrical response speed of the bonding wire, high-frequency signals are emitted first to quickly capture defects in surface and contact resistance. After the high-frequency signal is emitted, the system automatically switches to the medium-frequency signal mode to evaluate the surface effect and current distribution characteristics of the bonding wire. After the medium-frequency signal is emitted, the system automatically switches to the low-frequency signal mode to detect the overall conductivity and capacitance effect of the bonding wire.

[0065] Specifically, high-frequency signals have high transmission speed and strong penetration ability, but signal attenuation is more pronounced when transmitted through wire bonding, especially when the contact resistance of the wire bonding is high, causing rapid signal energy loss. The signal source generates a high-precision signal through a high-frequency oscillator to ensure signal frequency stability.

[0066] The advantage of intermediate frequency (IF) signals lies in their ability to penetrate solder joint areas where high-frequency signals struggle to transmit, while maintaining high accuracy. During wire bonding, monitoring the IF signal transmission is crucial, with particular attention paid to the skin effect, where current density concentrates on the conductor surface, causing signal energy to propagate along the surface. The skin effect is more pronounced with IF signals than with high-frequency signals.

[0067] Low-frequency signals experience minimal attenuation and can transmit more stably in wire bonding, but they are more sensitive to the capacitive effects of the wires. Capacitive effects can cause phase delays or signal reflections in the wires, especially with long wires or poorly connected solder joints. Low-frequency signal transmission is primarily used to detect wire integrity and the stability of solder joint contact.

[0068] Receiving multi-frequency electrical signals transmitted via wire bonding and acquiring the signal strength of each frequency band in real time includes the following steps:

[0069] The receiver synchronously receives signals from various frequency bands and adjusts the signal levels of different frequency bands in real time through an automatic gain control mechanism. The adjusted signals are amplified by a low-noise amplifier and noise is suppressed by a bandpass filter. After the signals are amplified and noise is suppressed, the receiver measures the signal power and phase of each frequency band to evaluate the transmission loss of the signal in the bonding wire. The measured power and phase are converted from analog to digital by a data acquisition card to obtain the signal strength of each frequency band.

[0070] Specifically, the formula for automatic gain control is:

[0071]

[0072] Where G is the receiver gain, V target It is the target voltage expected by the receiver, V in It is the received signal input voltage;

[0073] The expression for the received signal power is:

[0074] P = P t +G t +GL(f);

[0075] Where P is the original received signal power, P t It is the transmitted signal power, G t L is the transmitter gain, and L(f) is the transmission loss at the signal frequency f, where f is the signal frequency.

[0076] By calculating the signal power, the attenuation of the signal during transmission in the bonding wire can be inferred. The transmission loss of the bonding wire reflects its conductivity and electrical characteristics at different frequencies.

[0077] High-frequency bands typically experience higher losses and relatively lower signal power. Excessive power attenuation in high-frequency signals may indicate insufficient conductivity of the solder wire or excessively high contact resistance at the solder joint.

[0078] Mid-frequency band: Loss is relatively low, and signal power is relatively stable. Abnormal attenuation in the mid-frequency band may indicate problems such as localized damage to the bonding wire or poor solder joints.

[0079] Low frequency band: Minimal loss, but susceptible to capacitive effects. Abnormal power attenuation in low frequency signals may indicate excessive capacitive effects in the wire bonding process.

[0080] The expression for the phase change of a signal is:

[0081]

[0082] Where Δφ is the phase change, d is the length of the bonding wire, v is the speed at which the signal propagates in the bonding wire, and π is a mathematical constant.

[0083] The magnitude of phase change can reflect the impedance characteristics and electrical performance of the bonding wire:

[0084] Significant phase change: If the phase change of the signal in the bonding wire is abnormal, it may indicate problems such as impedance mismatch, poor solder joint contact, or capacitance effect.

[0085] Abnormal phase fluctuations: If the phase changes frequently in a certain frequency band, it may mean that there is a poor solder joint or breakage in the wire bonding.

[0086] Phase delay: Phase delay in low-frequency signals is usually related to capacitance effect. If the phase shift is too large, it may mean that the capacitance effect of the bonding wire is too strong, which will affect signal transmission.

[0087] By monitoring phase changes, the electrical connection quality of the soldered wires can be further assessed, especially during high-frequency signal transmission, where impedance matching has a significant impact on phase changes. If an abnormal phase change is detected, the soldered wire will be marked as requiring inspection.

[0088] Real-time monitoring of wire bonding temperature changes and generation of temperature data includes the following steps:

[0089] During the transmission and reception of multi-frequency signals, the temperature changes of the welding line and its surrounding environment are continuously monitored to obtain the temperature data of the welding point in real time and generate an analog temperature signal; the analog temperature signal is converted into a digital signal to generate temperature data; the generated temperature data is synchronized with the multi-frequency signal strength in time and stored.

[0090] Temperature compensation is performed on the received signal strength based on temperature data. The process of generating temperature-compensated signal strength data includes the following steps.

[0091] Extract temperature data, and calculate the actual resistance at the current temperature based on the characteristics of the wire bonding material. The expression is as follows:

[0092] R(T) = R0[1 + α(T - T0)];

[0093] Where R(T) is the wire bonding resistance at the real-time wire bonding temperature T, R0 is the resistance at the reference temperature T0, α is the temperature coefficient of the wire bonding material, T is the real-time wire bonding temperature, and T0 is the reference temperature.

[0094] Based on the change in resistance, the change in received signal power can be calculated using the following expression:

[0095]

[0096] Based on the received signal power and its variations, signal strength compensation is performed for each frequency band, expressed as follows:

[0097] P comp =P - ΔP(T);

[0098] Among them, P comp is the compensated signal received power, and P is the original signal received power.

[0099] Detecting the thermal noise level in wire bonding involves the following steps:

[0100] Convert the generated temperature data points into absolute temperatures;

[0101] Based on the temperature and bandwidth of the bonding wire, the thermal noise power of each frequency band is calculated using the following expression:

[0102]

[0103] Where, is the thermal noise power, k B It is the Boltzmann constant, T C It is the converted absolute temperature, and Δf is the signal bandwidth;

[0104] Based on the material properties of the bonding wire, environmental conditions, and historical data, the thermal noise threshold is set to N. thr The calculated thermal noise power for each frequency band is compared with the thermal noise threshold to determine whether there is any noise anomaly.

[0105] Specifically, if N T >N thr If N exceeds the threshold, it indicates that the thermal noise in that frequency band may be abnormal; T ≤N thr If so, the thermal noise in that frequency band is within the normal range.

[0106] The process of transmitting a high-frequency pulse signal to the bonding wire, detecting the reflection time and waveform characteristics of the signal within the bonding wire, and identifying physical defects in the bonding wire includes the following steps.

[0107] The time-domain reflectometer is activated to send a high-frequency pulse signal to the starting point of the bonding wire. The reflected signal generated in the bonding wire is acquired in real time, and the time difference between the reflected signal and the transmitted signal and the voltage change of the reflected waveform are recorded to generate waveform data. The acquired reflected waveform is compared point by point with the standard waveform in the historical database to analyze the amplitude difference, phase change and reflection time change of the waveform. Based on the analysis results, the location of the defect in the bonding wire is determined and the type of defect is judged.

[0108] Specifically, in this embodiment, defect types include fracture, poor solder joint, and porosity;

[0109] Breakage: If the bonding wire breaks, the reflected signal will produce a strong amplitude change at the break point. The waveform may suddenly stop or rise sharply, and the reflection time will be advanced.

[0110] Cold solder joint: A cold solder joint will cause a slight change in waveform amplitude and weaker signal reflection, but the waveform may have slight fluctuations or distortion.

[0111] Stomata: Stomata usually cause abnormal peaks or troughs in the reflected waveform, and the reflection time may be slightly delayed.

[0112] The steps for comprehensively analyzing the intensity of multi-frequency signals after temperature compensation, thermal noise level, and time-domain reflection waveform characteristics to determine the quality of wire bonding include the following:

[0113] The signal strength of each frequency band after temperature compensation is compared with the reference signal strength of that band to evaluate the transmission performance of the bonding wire at different frequencies. The actual measured thermal noise power of each frequency band is compared with the theoretical thermal noise power to determine whether the resistance performance of the bonding wire is normal. The time-domain reflection test results are reviewed to confirm whether there are any abnormalities in the reflected waveform. If the multi-frequency signal is stable in all frequency bands during transmission, the thermal noise level is normal, and no abnormalities are found in the time-domain reflection test, the bonding wire is deemed to be of qualified quality. If any signal frequency band shows instability, excessive thermal noise, or defects in the time-domain reflection test, the bonding wire is deemed to be unqualified.

[0114] In summary, this invention introduces multi-frequency signal transmission and reception, sequentially transmitting high-frequency, mid-frequency, and low-frequency signals to comprehensively evaluate the transmission performance of the bonding wire at different frequency bands, overcoming the shortcomings of existing technologies that only detect signals in a single frequency band. Simultaneously, by combining temperature detection and temperature compensation, it monitors the temperature changes of the bonding wire and its surrounding environment in real time, and performs temperature compensation for signal strength based on the characteristics of the bonding wire material, effectively solving the problem of inaccurate signal strength measurement caused by environmental temperature fluctuations. Furthermore, thermal noise detection can detect the thermal noise level of the bonding wire, improving the accuracy of evaluating the bonding wire's resistance performance. Through time-domain reflection, physical defects in the bonding wire are detected, and combined with the characteristics of the reflected waveform, the defect location is accurately located, improving the detection accuracy of time-domain reflection technology. In comprehensive data analysis, all detection data are integrated and analyzed to achieve all-round detection of the bonding wire quality, significantly improving the accuracy and reliability of the detection.

[0115] Example 2, referring to Table 1, is the second embodiment of the present invention. To further verify the technical solution of the present invention, experimental simulation data of an automated inspection system for semiconductor packaging wire bonding quality are provided.

[0116] In this experiment, two detection methods were used to test three sets of bonding wires: one was the existing single-frequency signal detection method, and the other was the multi-frequency signal detection system of this invention. The existing method only transmits and receives signals of a single frequency, ignoring the impact of temperature changes on signal strength and failing to detect thermal noise. In contrast, the system of this invention sequentially transmits high-frequency (10MHz), intermediate-frequency (1MHz), and low-frequency (100kHz) signals, processes the signals through automatic gain control, bandpass filtering, and a low-noise amplifier, and performs real-time temperature monitoring and compensation while simultaneously detecting thermal noise levels.

[0117] The experiment first tested three sets of bonding wire samples (bonded wire A, bonded wire B, and bonded wire C). For each bonded wire, high-frequency, mid-frequency, and low-frequency signals were transmitted sequentially, and the signal strength of each frequency band was recorded. The experiment was conducted under different temperature conditions to simulate temperature fluctuations in actual working environments. Existing technologies directly record signal strength changes; however, this invention first monitors the temperature, extracts the temperature data, performs temperature compensation, and calculates the temperature-compensated signal strength. Simultaneously, this invention detects the thermal noise level of each frequency band to ensure the stability of signal transmission.

[0118] At the start of the experiment, the high-frequency signal was set to 10MHz, the intermediate-frequency signal to 1MHz, and the low-frequency signal to 100kHz. In existing technologies, due to the lack of temperature compensation, the signal strength significantly decreases with increasing temperature, especially in the high-frequency and intermediate-frequency ranges. However, this invention maintains stable signal strength at different temperatures through temperature compensation.

[0119] The details are shown in Table 1 below:

[0120] Table 1 Comparison of Experimental Data

[0121]

[0122] The data in the table clearly shows that the present invention has significant advantages over the prior art in wire bonding quality inspection.

[0123] First, existing technologies generally exhibit low signal strength at high frequencies, especially with significant signal attenuation as temperature increases. For example, at 35°C, existing technologies achieve a high-frequency signal strength of only -14.0 dBm for wire C, while the system of this invention, after temperature compensation, maintains the high-frequency signal strength of wire C at -12.0 dBm and further optimizes it to -11.7 dBm. This demonstrates that the present invention, through real-time temperature monitoring and compensation mechanisms, effectively suppresses the impact of temperature fluctuations on signal transmission performance, ensuring more stable and accurate signal strength measurements.

[0124] Secondly, existing technologies also exhibit significant signal attenuation in the mid-frequency and low-frequency bands. For example, existing technologies produce a mid-frequency signal strength of -15.2 dBm and a low-frequency signal strength of -17.5 dBm for wire B at 30°C. This invention, through multi-frequency signal transmission and automatic gain control mechanisms, achieves a mid-frequency signal strength of -13.0 dBm and a low-frequency signal strength of -14.6 dBm for wire B at the same temperature, significantly outperforming existing technologies. This result demonstrates that the system of this invention can more comprehensively and accurately evaluate the transmission performance of wires in different frequency bands.

[0125] Furthermore, the comparison of thermal noise levels further illustrates the innovation of this invention. Existing technologies have thermal noise levels between 45-58 nV / √Hz, while the system of this invention, through a low-noise amplifier and bandpass filter, significantly reduces the thermal noise level, maintaining it between 22-28 nV / √Hz. This means that this invention performs superiorly in noise suppression, effectively reducing noise interference with signal measurements and improving detection reliability.

[0126] In summary, the multi-frequency signal detection system of this invention significantly improves the accuracy and stability of wire bonding detection. Compared with existing technologies, this invention can more comprehensively evaluate the transmission performance of wire bonding in high, medium, and low frequency bands, monitor and compensate for temperature in real time, and reduce the impact of temperature fluctuations on signal transmission. Furthermore, this invention also demonstrates significant advantages in suppressing thermal noise, ensuring the accuracy of signal detection.

[0127] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An automated inspection system for the quality of wire bonding in semiconductor packaging, characterized in that: include, The multi-frequency signal transmission module is used to sequentially transmit high-frequency, medium-frequency, and low-frequency electrical signals to the bonding wire; The receiving module is used to receive multi-frequency electrical signals transmitted by the bonding wire and to collect the signal strength of each frequency band in real time. The temperature detection module is used to monitor the temperature changes of the bonding wire in real time and generate temperature data; The temperature compensation module is used to perform temperature compensation on the signal strength of each frequency band received by the receiving module based on temperature data, generating compensated multi-frequency signal strength data through the following steps. Extract temperature data, and calculate the actual resistance at the current temperature based on the characteristics of the bonding wire material. The expression is as follows: ； in, Real-time wire bonding temperature The bonding resistance below, Reference temperature The resistance below, It is the temperature coefficient of the wire bonding material. It is the real-time wire bonding temperature. This is a reference temperature; Thermal noise detection module, used to detect the thermal noise level in the wire bonding; The time-domain reflectometry module is used to transmit high-frequency pulse signals to the bonding wire, detect the reflection time and waveform characteristics of the signal in the bonding wire, and identify physical defects in the bonding wire. The data analysis module is used to comprehensively analyze the intensity of multi-frequency signals, thermal noise level, and time-domain reflection waveform characteristics after temperature compensation to determine the quality of the wire bonding, including the following steps. The signal strength of each frequency band after temperature compensation is compared with the reference signal strength of that frequency band to evaluate the transmission performance of the bonding wire at different frequencies. Compare the actual measured thermal noise power of each frequency band with the theoretical thermal noise power to determine whether the wire bonding resistance performance is normal. Review the time-domain reflectance test results to confirm whether there are any abnormalities in the reflected waveform; If the multi-frequency signal performs stably across all frequency bands during transmission, the thermal noise level is normal, and no abnormalities are detected by time-domain reflection detection, the wire bonding quality is deemed acceptable. If any signal frequency band exhibits instability, excessive thermal noise, or defects detected in time-domain reflection, the wire bonding is deemed unqualified.

2. The automated inspection system for semiconductor packaging wire bonding quality as described in claim 1, characterized in that: The process of sequentially transmitting high-frequency, medium-frequency, and low-frequency electrical signals to the bonding wire includes the following steps: The frequency range of the signal source is set according to the characteristics of the bonding wire material and the sensitivity of the bonding wire's electrical performance, generating high-frequency, medium-frequency, and low-frequency signals; Based on the physical characteristics of the signal and the electrical response speed of the bonding wire, high-frequency signals are preferentially emitted to quickly capture defects in surface and contact resistance; After the high-frequency signal transmission is completed, it automatically switches to the medium-frequency signal mode for transmission to evaluate the surface effect and current distribution characteristics of the bonding wire; After the intermediate frequency signal is transmitted, it automatically switches to the low frequency signal mode to transmit and detect the overall conductivity and capacitance effect of the bonding wire.

3. The automated inspection system for semiconductor packaging wire bonding quality as described in claim 2, characterized in that: Receiving multi-frequency electrical signals transmitted via wire bonding and acquiring the signal strength of each frequency band in real time includes the following steps: The receiver synchronously receives signals from various frequency bands and adjusts the signal levels of different frequency bands in real time through an automatic gain control mechanism. The regulated signal is amplified by a low-noise amplifier, and a bandpass filter is used to suppress noise in the amplified signal. After the signal is amplified and noise is suppressed, the receiver measures the signal power and phase for each frequency band to evaluate the signal transmission loss in the bonding wire. The measured power and phase are converted from analog to digital by a data acquisition card, thus obtaining the signal strength of each frequency band.

4. The automated inspection system for semiconductor packaging wire bonding quality as described in claim 3, characterized in that: Real-time monitoring of wire bonding temperature changes and generation of temperature data includes the following steps: During the transmission and reception of multi-frequency signals, the temperature changes of the welding wire and its surrounding environment are continuously monitored, the temperature data of the welding point is obtained in real time, and a simulated temperature signal is generated. The analog temperature signal is converted into a digital signal to generate temperature data; The generated temperature data is synchronized with the signal strength of each frequency band and then stored.

5. The automated inspection system for semiconductor packaging wire bonding quality as described in claim 1, characterized in that: Based on the change in resistance, the change in received signal power can be calculated using the following expression: ； in, It is the change in power. It is the receiver gain.

6. The automated inspection system for semiconductor packaging wire bonding quality as described in claim 5, characterized in that: Based on the received signal power and its variations, signal strength compensation is performed for each frequency band, expressed as follows: ； in, It is the compensated signal reception power. This is the original signal received power.

7. The automated inspection system for semiconductor packaging wire bonding quality as described in claim 6, characterized in that: Detecting the thermal noise level in wire bonding involves the following steps: Convert the generated temperature data points into absolute temperatures; Based on the temperature and bandwidth of the bonding wire, the thermal noise power of each frequency band is calculated using the following expression: ； in, It is thermal noise power. It is Boltzmann's constant. It is the converted absolute temperature. It is the signal bandwidth; Set thermal noise thresholds based on the material properties of the bonding wire, environmental conditions, and historical data; The calculated thermal noise power for each frequency band is compared with the thermal noise threshold to determine whether there is any noise anomaly.

8. The automated inspection system for semiconductor packaging wire bonding quality as described in claim 7, characterized in that: The process of transmitting a high-frequency pulse signal to the bonding wire, detecting the reflection time and waveform characteristics of the signal within the bonding wire, and identifying physical defects in the bonding wire includes the following steps. Start the time-domain reflectometer, send a high-frequency pulse signal to the starting point of the bonding wire, collect the reflected signal generated in the bonding wire in real time, and record the time difference between the reflected signal and the transmitted signal and the voltage change of the reflected waveform to generate waveform data; The collected reflected waveforms are compared point by point with the standard waveforms in the historical database to analyze the differences in waveform amplitude, phase change and reflection time. Based on the analysis results, the location of defects in the solder wire is determined, and the type of defect is identified.

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