A manufacturing process of an HDI board for a notebook camera module

Abstract

The application discloses a kind of HDI board manufacturing processes for notebook camera module, comprising: the substrate is treated by multi-frequency acoustic wave penetration and temperature gradient, obtains substrate pre-check data;In the process of laser drilling, short pulse multi-frequency acoustic wave and local heat regulation are applied to target hole area, and micro-hole acoustic reflection data are obtained;Before chemical copper deposition treatment, the temperature of multiple regions on the board surface is independently regulated, and acoustic scanning data are recorded to form regional acoustic feature map;In the process of chemical copper deposition, acoustic wave excitation is carried out at preset time interval to obtain copper deposition process monitoring data;Periodic thermal excitation and fluid disturbance are applied in the process of electroplating to obtain electroplating dynamic monitoring data;After electroplating is completed, temperature cycle and stress excitation treatment are carried out to obtain micro-via internal structure evaluation results.The technical scheme of the present application can accurately identify and screen micro-via structures with bubble micro-migration tendency during the manufacturing process, effectively improve the long-term reliability and use stability of HDI board.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection in the manufacturing process of high-density interconnection printed circuit boards, and in particular to a manufacturing process of an HDI board for a notebook camera module. BACKGROUND

[0002] The HDI (High Density Interconnection) board for a notebook camera module is a high-density interconnection printed circuit board specially designed to support the electrical connection and signal transmission of the camera module. This HDI board usually adopts a multi-layer structure design, containing 4-8 circuit layers, and the interlayers are interconnected through micro vias, with a total thickness usually in the range of 0.6-0.8 millimeters. Due to the pursuit of thinness of notebook computers, the space for the camera module is extremely limited, and the HDI board needs to realize high-density component layout and complex signal line arrangement in a very small area, while also meeting the electrical performance requirements of high-definition video transmission.

[0003] The existing HDI board manufacturing process mainly includes substrate selection, laser drilling, micro via plating, line forming, and surface treatment steps. Among them, the micro via plating link adopts a combination of chemical deposition and electroplating, depositing a thin copper seed layer on the insulating resin hole wall first, and then thickening the copper layer through electrochemical reaction until a reliable conductive path is formed. However, due to the extremely small diameter (usually 30-50 microns) and high aspect ratio of the micro vias of the camera module HDI board, the current distribution is uneven during electroplating, and the solution flow is limited, which easily leads to the formation of micro bubbles inside the micro vias. These bubbles may be completely covered by the subsequent deposited copper layer during the electroplating process, forming a structure that appears complete but has internal cavities. Traditional X-ray and AOI (Automated Optical Inspection) detection mainly focuses on static defects and is difficult to detect such internal bubbles covered by the copper layer. In addition, such defects do not immediately affect product functionality in the initial state, but in application scenarios such as long-time video conferencing of the camera, the heat generated by continuous work will cause these bubbles to expand and migrate, eventually causing intermittent connection failures, seriously affecting user experience. SUMMARY

[0004] The main purpose of the present application is to solve the technical problem that internal bubbles covered by the copper layer are difficult to detect in the existing micro via manufacturing process of the HDI board.

[0005] The application provides a manufacturing process of an HDI plate for a laptop camera module.

[0006] The substrate is subjected to multi-frequency acoustic wave penetration and temperature gradient treatment to obtain acoustic response data and thermal response data of the substrate, and the acoustic response data and the thermal response data are used as substrate pre-check data.

[0007] According to the substrate pre-check data, a short-pulse multi-frequency acoustic wave is applied to a target hole area in a laser drilling process, acoustic reflection signals at the moment of drilling are recorded, and local heat regulation is performed on a hole wall area to obtain micro-hole acoustic reflection data.

[0008] Before chemical copper deposition treatment, according to the micro-hole acoustic reflection data, temperature independent regulation is performed on multiple areas on the plate surface, multi-frequency acoustic scanning data of hole walls in each area under thermal pulse excitation are recorded, and a regional acoustic feature map is formed.

[0009] During the chemical copper deposition process, according to the regional acoustic feature map, multi-frequency acoustic wave excitation is performed on the hole area at a preset time interval, acoustic reflection signal attenuation curves in the metal seed layer generation process are recorded, and copper deposition process monitoring data are obtained.

[0010] During the electroplating process, according to the copper deposition process monitoring data, periodic thermal excitation and fluid disturbance are applied to the plate surface, the propagation characteristics of multi-frequency acoustic waves in the electroplating solution are recorded, and electroplating dynamic monitoring data are obtained through adaptive signal processing.

[0011] After the electroplating is completed, according to the electroplating dynamic monitoring data, temperature cycling and stress excitation treatment are performed on the finished product, hole acoustic wave reflection data are recorded, and micro-via internal structure evaluation results are obtained through multi-dimensional data analysis.

[0012] Preferably, the multi-frequency acoustic wave penetration and temperature gradient treatment of the substrate to obtain acoustic response data and thermal response data of the substrate, and the acoustic response data and the thermal response data are used as substrate pre-check data, comprising:

[0013] A first frequency acoustic wave is applied to the acoustic coupling medium layer arranged between the adjacent resin layers of the substrate, and acoustic wave buffer stress data and interlayer bonding strength data of the acoustic coupling medium layer are recorded.

[0014] According to the acoustic wave buffer stress data and the interlayer bonding strength data, a second frequency acoustic wave is applied to the interface between the resin layer and the copper foil layer of the substrate, and acoustic wave amplitude data and acoustic wave phase difference data of the interface bonding part are recorded.

[0015] determining a first temperature interval range according to the acoustic wave amplitude data, applying a first temperature gradient to the substrate in the first temperature interval, recording first thermal stress distribution data; determining a second temperature interval range according to the acoustic wave phase difference data, applying a second temperature gradient to the substrate in the second temperature interval, recording second thermal stress distribution data; performing acoustic scanning on the thermal stress concentration area through the acoustic coupling medium layer according to the first thermal stress distribution data and the second thermal stress distribution data, and recording acoustic characteristic data of the micro-cavity and the interlayer bonding abnormal area inside the substrate;

[0016] performing stress compensation processing on the acoustic wave buffer stress data and the interlayer bonding strength data according to the thermal stress distribution data, performing abnormal correction processing on the acoustic wave amplitude data and the acoustic wave phase difference data according to the acoustic characteristic data, and combining the data after compensation processing and correction processing to form substrate pre-check data.

[0017] Preferably, the acoustic wave buffer stress data and the interlayer bonding strength data are used to apply second-band acoustic waves to the interface between the resin layer and the copper foil layer of the substrate, and the acoustic wave amplitude data and the acoustic wave phase difference data of the interface bonding part are recorded.

[0018] determining acoustic wave action parameters according to the acoustic wave buffer stress data, applying first-sub-band acoustic waves corresponding to the acoustic wave action parameters to the interface bonding part between the rough area of the outer copper foil surface of the substrate and the adjacent resin layer, and recording the acoustic wave scattering intensity data of the rough area of the outer copper foil surface.

[0019] determining acoustic wave penetration depth parameters according to the interlayer bonding strength data, applying second-sub-band acoustic waves corresponding to the acoustic wave penetration depth parameters to the interface bonding part between the inner copper foil and the resin layer of the substrate in the high scattering area indicated by the acoustic wave scattering intensity data, and recording the acoustic wave attenuation data of the interface between the inner copper foil and the resin layer.

[0020] performing amplitude superposition processing on the acoustic wave scattering intensity data and the acoustic wave attenuation data to form acoustic wave amplitude data, and performing phase superposition processing on the acoustic wave scattering intensity data and the acoustic wave attenuation data to form acoustic wave phase difference data.

[0021] Preferably, the substrate pre-check data is used to apply short-pulse multi-frequency acoustic waves to the target hole area during laser drilling, record acoustic reflection signals at the drilling moment, and perform local heat regulation on the hole wall area to obtain micro-hole acoustic reflection data, including:

[0022] According to the substrate pre-check data, the range and timing of the acoustic wave are determined, and a first frequency band short pulse acoustic wave corresponding to the range and timing of the acoustic wave is applied to the target hole area, and the acoustic reflection reference data of the substrate before drilling is recorded;

[0023] According to the acoustic reflection reference data, a second frequency band short pulse acoustic wave is applied to the hole wall layer by layer during the laser drilling ablation process, and the amplitude mutation data and phase shift data of the acoustic wave during each layer ablation process are recorded;

[0024] According to the amplitude mutation data of the acoustic wave, the first temperature control parameter is determined, and the first local temperature gradient corresponding to the first temperature control parameter is applied to the hole wall area, and the first hole wall temperature response data is recorded; according to the phase shift data, the second temperature control parameter is determined, and the second local temperature gradient corresponding to the second temperature control parameter is applied to the hole wall area, and the second hole wall temperature response data is recorded;

[0025] According to the first hole wall temperature response data and the second hole wall temperature response data, a third frequency band short pulse acoustic wave is applied to the hole wall, and the acoustic scattering data of the micro crack of the hole wall and the acoustic attenuation data of the resin residue are recorded, and the amplitude mutation data, the phase shift data, the first hole wall temperature response data, the second hole wall temperature response data, the acoustic scattering data of the micro crack of the hole wall and the acoustic attenuation data of the resin residue are combined to form the micro hole acoustic reflection data.

[0026] Preferably, according to the acoustic reflection reference data, a second frequency band short pulse acoustic wave is applied to the hole wall layer by layer during the laser drilling ablation process, and the amplitude mutation data and phase shift data of the acoustic wave during each layer ablation process are recorded, comprising:

[0027] According to the acoustic reflection reference data, a first sub-frequency band short pulse acoustic wave is applied to the ablation area of the outer copper foil, and the metal layer acoustic reflection data and the copper foil residual distribution data during the ablation process of the outer copper foil are recorded;

[0028] According to the metal layer acoustic reflection data, a second sub-frequency band short pulse acoustic wave is applied to the alternating ablation area of the resin layer and the inner copper foil, and the material peeling acoustic characteristic data of the resin-metal interface and the resin decomposition acoustic characteristic data are recorded;

[0029] The metal layer acoustic reflection data, the copper foil residual distribution data, the material peeling acoustic characteristic data and the resin decomposition acoustic characteristic data are combined and analyzed to form the amplitude mutation data and the phase shift data of the acoustic wave.

[0030] Preferably, before the chemical copper deposition process, the temperature of multiple regions on the plate surface is independently regulated according to the micro-hole acoustic reflection data, the multi-frequency acoustic scanning data of the hole wall of each region under the excitation of a thermal pulse is recorded, and a regional acoustic characteristic map is formed, including:

[0031] Before the chemical copper deposition process, the plate surface is divided into multiple temperature-independent regulation units according to the acoustic amplitude mutation region and the phase shift region in the micro-hole acoustic reflection data, and an independent temperature control parameter is set for each temperature-independent regulation unit;

[0032] According to the temperature control parameter of each temperature-independent regulation unit, a first thermal pulse wave is applied to the hole wall of each region, a first frequency band acoustic scanning wave is applied to the hole wall at the peak value of the first thermal pulse wave, and acoustic scattering data caused by the transient expansion of the hole wall is recorded;

[0033] According to the acoustic scattering data, the stress response parameters of the hole wall of each region are determined, a second thermal pulse wave is applied to each temperature-independent regulation unit, a second frequency band acoustic scanning wave is applied to the hole wall at the valley value of the second thermal pulse wave, and acoustic attenuation data caused by the transient contraction of the hole wall is recorded;

[0034] According to the acoustic attenuation data, the strain distribution parameters of the hole wall of each region are determined, a third thermal pulse wave is applied to each temperature-independent regulation unit, a third frequency band acoustic scanning wave is applied to the hole wall during the duration of the third thermal pulse wave, and acoustic characteristic data of the micro-crack of the hole wall and migration trend data of the hole are recorded;

[0035] The acoustic scattering data, the acoustic attenuation data, the acoustic characteristic data of the micro-crack of the hole wall, and the migration trend data of the hole are combined according to the temperature-independent regulation unit to form a regional acoustic characteristic map.

[0036] Preferably, during the chemical copper deposition process, according to the regional acoustic characteristic map, a multi-frequency acoustic wave is excited to the hole region at a preset time interval, the acoustic reflection signal attenuation curve in the metal seed layer generation process is recorded, and the copper deposition process monitoring data is obtained, including:

[0037] During the chemical copper deposition process, the copper deposition monitoring time sequence of each hole region is determined according to the regional acoustic characteristic map and the preset time interval, the chemical copper deposition solution flow is paused at the pause point of each copper deposition monitoring time sequence, and a copper deposition initiation detection wave is applied to the hole region. The acoustic reflection characteristic data of the metal seed layer nucleation stage is recorded;

[0038] According to the acoustic reflection characteristic data, a copper deposition growth detection wave is applied to different hole regions, and metal grain growth distribution data and interface bonding state data are recorded;

[0039] According to the metal grain growth distribution data and the interface bonding state data, a copper plating process detection wave is applied to the hole area, a seed layer continuity change curve and a hole wall coverage change curve are recorded;

[0040] According to the preset time interval, dynamic characteristic analysis is performed on the seed layer continuity change curve and the hole wall coverage change curve, the acoustic reflection characteristic data, the metal grain growth distribution data, the interface bonding state data and the dynamic characteristic analysis result are combined to form copper plating process monitoring data.

[0041] Preferably, in the electroplating process, according to the copper plating process monitoring data, a periodic thermal excitation and a fluid disturbance are applied to the board surface, the propagation characteristics of multi-frequency acoustic waves in the electroplating solution are recorded, and electroplating dynamic monitoring data is obtained through adaptive signal processing, including:

[0042] In the electroplating process, according to the seed layer continuity change curve in the copper plating process monitoring data, a first electroplating thermal pulse is applied to the high-density micro-hole cluster area, and a second electroplating thermal pulse is applied to the peripheral wiring area, and the temperature gradient distribution data of the micro-hole area and the wiring area is recorded;

[0043] According to the temperature gradient distribution data, a first fluid disturbance is applied to the high-density micro-hole cluster area, and a second fluid disturbance is applied to the peripheral wiring area, and an electroplating acoustic detection wave is applied to the deep and shallow micro-hole area under the action of the double fluid disturbance, and the acoustic propagation attenuation data of different depth-diameter ratio micro-holes is recorded;

[0044] According to the acoustic propagation attenuation data, a low-frequency electroplating monitoring wave is applied to the high-density micro-hole cluster area, and a high-frequency electroplating monitoring wave is applied to the peripheral wiring area, and the micro-hole bottom current density distribution data and the hole wall plating layer stress distribution data are recorded;

[0045] The current density distribution data is subjected to regional compensation operation, and the plating layer thickness distribution curve of deep and shallow micro-holes is recorded, and the hole wall plating layer stress distribution data is subjected to hierarchical processing, and the bubble migration characteristic curve of different depth-diameter ratio micro-holes is recorded;

[0046] The plating layer thickness distribution curve and the bubble migration characteristic curve are subjected to adaptive signal filtering processing, and the temperature gradient distribution data, the acoustic propagation attenuation data, the current density distribution data, the hole wall plating layer stress distribution data, the plating layer thickness distribution curve after adaptive signal filtering processing and the bubble migration characteristic curve after adaptive signal filtering processing are combined to form electroplating dynamic monitoring data.

[0047] Preferably, after the electroplating is completed, the finished product is subjected to temperature cycling and stress excitation treatment according to the electroplating dynamic monitoring data, acoustic wave reflection data in the hole are recorded, and micro-via internal structure evaluation results are obtained through multi-dimensional data analysis, including:

[0048] After the electroplating is completed, the micro-hole inner wall coating is evaluated according to the electroplating dynamic monitoring data, the temperature cycling parameters and the stress excitation parameters are determined, the finished product is subjected to first temperature cycling, and the thermal cycling gradient data and the cyclic stress accumulation data of each micro-hole region are recorded;

[0049] According to the thermal cycling gradient data and the cyclic stress accumulation data, the finished product is subjected to second temperature cycling, and the finished product evaluation acoustic wave is applied to the micro-hole inner wall, and the acoustic attenuation trend data and the acoustic phase shift characteristic data in the micro-hole are recorded;

[0050] According to the acoustic attenuation trend data and the acoustic phase shift characteristic data, mechanical stress excitation is applied to the micro-hole, and the structure deformation parameters and the void evolution data of the micro-hole inner wall coating are recorded;

[0051] The thermal cycling gradient data, the cyclic stress accumulation data, the acoustic attenuation trend data, the acoustic phase shift characteristic data, the structure deformation parameters and the void evolution data are comprehensively processed to form micro-via internal structure evaluation results.

[0052] During the entire preparation process, the detection and monitoring means of multi-frequency acoustic wave combined with temperature gradient are set at each stage described in the scheme, which can continuously track any risk factors that may cause bubbles or internal holes of the micro-hole before the micro-hole is completely formed and the metal layer is deposited. At the beginning of the manufacturing process, the substrate is subjected to multi-frequency acoustic wave penetration combined with temperature gradient treatment. In this way, acoustic response and thermal stress distribution information can be collected at the interface between the resin layer and the copper foil layer, as well as at the deep position of the stacked medium. These information can distinguish the areas with weak interlayer adhesion or containing micro voids, provide early warning for subsequent micro-hole processing, and record them in the substrate pre-check data. Subsequently, during the laser drilling stage, short pulse multi-frequency acoustic wave is applied to the target hole region, and local heat regulation is applied during ablation process, and the possible cracks or resin residues of the hole wall are identified by the changes of the amplitude and phase of the acoustic wave under different temperature conditions. With this real-time monitoring, potential defect areas can be found in time, so that subsequent metallization process will not blindly deposit copper layer on the hole wall with defects.

[0053] Before the chemical copper plating process, the scheme provides for independent temperature control of multiple areas, and records the multi-frequency acoustic scanning results of the hole wall under thermal pulse excitation. Through this approach, the distribution of micro-cracks or cavities in the substrate can be revealed block by block, and the corresponding regional acoustic feature map can be obtained. Subsequently, when formally entering the chemical copper plating process, the solution flow is paused at the pre-set time node, and multi-frequency acoustic waves are applied to the hole area again, and the attenuation trend of the acoustic reflection signal during the formation of the metal seed layer is continuously observed. If the seed layer appears to be not firmly attached or unevenly covered during growth, the acoustic wave will exhibit abnormal amplitude and attenuation curve on the hole wall surface, which can help determine whether internal cavities or micro-bubbles are being generated. These dynamic monitoring data can also be combined with the previously collected partition map to make targeted adjustments to the copper plating conditions to prevent defects from further developing.

[0054] In the electroplating stage, the scheme proposes to use the monitored seed layer state during copper plating to apply different thermal pulses and fluid disturbances to the cluster area of high-density micro-holes and the peripheral trace area, and to apply multi-frequency acoustic waves with adaptive signal processing to hole sites with different depth-to-diameter ratios. This allows for more precise capture of current non-uniformity at the bottom of micro-holes due to high aspect ratio, as well as the location where bubbles may accumulate. By observing acoustic propagation attenuation, hole wall stress distribution, and bubble migration curves in real time, current density can be reduced locally or solution flow can be enhanced in time, so that bubbles are excluded or exposed at an early stage of formation. Once cavities wrapped in copper layers are generated, they will also exhibit obvious signal abnormalities under the combined action of thermal pulses and acoustic waves, which can be further located and remedied.

[0055] When the electroplating is completed, temperature cycling and stress excitation methods are used in conjunction with acoustic wave reflection detection at this time, so that bubbles or hole wall voids that did not initially cause functional abnormalities but are prone to expansion under subsequent thermal expansion and mechanical vibration exhibit characteristic responses in the detection data. The combination of acoustic attenuation and phase shift, together with the recording of internal wall plating layer structure deformation and void evolution, can screen out micro-holes that still pose potential risks, and subsequent treatment can be taken according to the degree of void evolution. This continuous multi-stage acoustic and temperature coupling detection cycle controls the defect risk of the entire micro-via from the substrate to the finished product in the early visible range, avoiding the shortcomings of traditional methods that only perform single detection and cannot find copper layer covered bubbles.

[0056] By the above-mentioned manner, the micro-bubbles that are expected to be generated or have existed in the hole wall can be monitored and disposed in the whole process. The multi-frequency acoustic wave and the temperature regulation complement each other, so that any small cavity or poor bonding cannot be easily concealed. After the substrate defects are identified in the early stage, the drilling process is adjusted in time, the seed layer growth state is observed multiple times in the chemical copper plating stage, and the plating parameters are corrected, and in the later stage, the temperature and stress are also investigated in multiple dimensions in the finished state. These steps are connected in series to form a systematic screening and correction method for internal bubble defects, which significantly reduces the risk of intermittent failure of micro-holes due to thermal stress expansion in a high-speed signal transmission environment. As can be seen, this detection and manufacturing integrated process can convert the potential hidden dangers in the background into specific objects that can be monitored and prevented, solving the problem of difficult and timely discovery of bubbles hidden by the copper layer and unstable failure in the later stage. BRIEF DESCRIPTION OF DRAWINGS

[0057] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only show some of the embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0058] Figure 1 An embodiment schematic diagram of the HDI plate manufacturing process for the notebook camera module in the embodiments of the present application.

[0059] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0061] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement condition, etc. between the components in a certain posture, and if the certain posture changes, the directional indications also change accordingly.

[0062] In addition, the description related to "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In addition, "and / or" throughout the text includes three schemes, for example, A and / or B includes A technical scheme, B technical scheme, and A and B simultaneously meet the technical scheme; in addition, the technical schemes of various embodiments can be combined with each other, and it must be based on the realization of the technical personnel in the art, when the combination of technical schemes appears contradictory or cannot be realized, it should be considered that the combination of technical schemes does not exist, nor in the protection scope required by the present application.

[0063] An embodiment of the present application provides a manufacturing process of an HDI board for a notebook camera module. Figure 1 An embodiment of the present application provides a flow chart of a manufacturing process of an HDI board for a notebook camera module. In the embodiment, the method comprises:

[0064] Please refer to Figure 1 The substrate is subjected to multi-frequency acoustic wave penetration and temperature gradient treatment to obtain acoustic response data and thermal response data of the substrate, and the acoustic response data and the thermal response data are used as substrate pre-check data.

[0065] In an embodiment of the present application, the multi-frequency acoustic wave penetration and temperature gradient treatment of the substrate to obtain acoustic response data and thermal response data of the substrate, and the acoustic response data and the thermal response data are used as substrate pre-check data, comprising:

[0066] The acoustic coupling medium layer arranged between the adjacent resin layers of the substrate is subjected to first frequency band acoustic waves, and the acoustic wave buffer stress data and the interlayer bonding strength data of the acoustic coupling medium layer are recorded.

[0067] According to the acoustic wave buffer stress data and the interlayer bonding strength data, the second frequency band acoustic waves are applied to the interface between the resin layer and the copper foil layer of the substrate, and the acoustic wave amplitude data and the acoustic wave phase difference data of the interface bonding part are recorded.

[0068] According to the acoustic wave amplitude data, a first temperature interval range is determined, a first temperature gradient is applied to the substrate in the first temperature interval, and first thermal stress distribution data is recorded; according to the acoustic wave phase difference data, a second temperature interval range is determined, a second temperature gradient is applied to the substrate in the second temperature interval, and second thermal stress distribution data is recorded; according to the first thermal stress distribution data and the second thermal stress distribution data, the acoustic coupling medium layer is subjected to acoustic scanning on the thermal stress concentration area, and the acoustic characteristic data of the internal microcavity and the interlayer bonding abnormal area of the substrate is recorded.

[0069] According to the thermal stress distribution data, stress compensation processing is performed on the acoustic wave buffer stress data and the interlayer adhesion strength data, and according to the acoustic characteristic data, abnormal correction processing is performed on the acoustic wave amplitude data and the acoustic wave phase difference data. The data after compensation processing and correction processing are combined to form the substrate pre-inspection data.

[0070] The following specifically describes the steps involved in the above embodiments:

[0071] The acoustic coupling medium layer arranged between the adjacent resin layers of the substrate generally uses modified epoxy resin or elastomer modified resin material, and inorganic fillers (such as silica particles or alumina particles) can be added therein to improve the acoustic wave conduction performance. The coupling medium layer meets the requirements of electrical insulation and can maintain a stable structure under external stress and acoustic wave action. It is realized by introducing a thin layer of material between the resin layers during the lamination stage, and after curing, it can be closely attached to the adjacent resin layer and has moderate elasticity. If modified epoxy resin is used, the material has high adhesion and mechanical properties after thermal curing; if elastomer modified composite resin is used, the internal elastic component can buffer the interlayer stress and allow the acoustic wave to propagate in the medium layer with a small attenuation rate. When the first frequency band acoustic wave is applied to this medium layer, a multi-frequency ultrasonic detection system can be used as an instrument, and the detection probe is coupled with water-based or oil-based coupling agent outside the board. The first frequency band can be selected in the range of about 5MHz to 15MHz, which is beneficial to penetrate the medium layer and detect its absorption or transmission characteristics of vibration. The acoustic wave buffer stress data recorded in this process reflects the numerical value of the stress absorption capacity of the medium material, and the interlayer adhesion strength data quantifies the firmness of the medium layer and the resin by analyzing the interface reflection coefficient and phase shift. The reason for using this frequency band is to balance the penetration depth and resolution, which is convenient for identifying small adhesion abnormalities or excessive hardening areas in the medium layer with low thickness. After the above detection is completed, the acoustic response of the internal coupling medium layer under no significant temperature load can be understood, which provides a reference for identifying deep defects of the substrate.

[0072] According to the first frequency band detection results (sound wave buffer stress data and interlayer adhesion strength data), the weak adhesion parts or stress abnormal areas of the coupling medium layer can be located. When the resin layer and the copper foil layer interface of these parts are further detected, the second frequency band acoustic wave can be applied. To meet the needs of fine imaging and defect identification of the metal-resin interface, the second frequency band can be selected in the range of about 15MHz to 30MHz, and the acoustic impedance difference is more likely to capture local voids or rough contact surfaces in this frequency band. During detection, the ultrasonic probe is aimed at the target interface area and combined with water-based coupling agent or film coupling method, so that the ultrasonic pulse penetrates through the upper layer of resin to reach the copper foil interface. If there are cracks or not closely attached in the interface, the receiving end will observe abnormal amplitude peak value or significant increase in phase shift in the echo signal. The amplitude data of the sound wave usually represents the reflectivity intensity of the interface at this frequency band, which is used to judge whether there is a larger cavity; the phase difference data is related to the local interface thickness perturbation or the refractive path between the material layers, which can be used to identify more subtle peeling signs. Through this step, the detection results between the coupling medium layer and the resin layer can be cross-verified, and the potential problem parts of the resin-copper foil interface can be further locked, providing a detection target area for subsequent temperature gradient loading.

[0073] According to the obtained sound wave amplitude data, the section where the larger voids or local material non-uniformity are located can be inferred, so as to set the first temperature interval; according to the phase difference data, the more subtle interface disturbance parts can be inferred, so as to set the second temperature interval. In specific implementation, local infrared radiation sources or temperature control tables can be used to apply different temperature gradients to these target sections, and the target area is continuously scanned in the previous frequency band (or a small step frequency band after adjustment) during the heating or cooling process, to record the first thermal stress distribution data and the second thermal stress distribution data. The first temperature interval can be selected between 40°C and 80°C, for example, to simulate the stress distribution under lower temperature load; the second temperature interval can be selected between 80°C and 120°C to observe the material mismatch behavior under higher temperature working environment. If there is a strong acoustic reflection amplitude mutation at a certain temperature section, it can be marked as a thermal stress concentration. After the recording of the two temperature intervals is completed, the acoustic coupling medium layer set in advance can be used to implement more precise acoustic scanning on these thermal stress concentration areas again. When the coupling medium layer conducts sound waves to the microcavities or bonding abnormalities, the reflected signal will have peak values or waveform distortions in amplitude and phase that are completely different from normal areas. Through this process, more explicit location and size information of the microcavities and interlayer abnormalities inside the substrate can be obtained. Combined with these data, the thermal stress accumulation that may occur in the material under different temperature intervals can be distinguished, to help judge the severity of the defect.

[0074] According to the thermal stress distribution data, the acoustic wave buffer stress data and the interlayer adhesion strength data can be stress compensated, that is, the parts with high stress concentration and low adhesion strength are marked as key hidden danger areas at the same spatial coordinates. At this time, the acoustic characteristic data is needed to correct the acoustic amplitude data and the phase difference data, especially the parts with obvious peak value deviation repeatedly appearing in multiple detections or different temperature gradients, which need to be given higher weight in the signal processing algorithm to confirm their authenticity. If some areas have high values due to local bubbles or transient noise in single detection, the removal or weight reduction processing can be done at this stage. After completing these corrections, all information after compensation and correction can be integrated into the same data set to form the substrate pre-detection data. The data contains the mechanical and acoustic matching between interfaces and the stress sensitivity under different temperature gradients, which can provide guidance for subsequent laser drilling and metallization process adjustment. For example, if it is found that the adhesion between layers is low and the thermal stress concentration is high, the ablation power can be reduced and the heat dissipation time can be prolonged in subsequent laser processing to avoid further tearing of the hole wall. If a large number of interface abnormalities are found, higher solution flowability or more uniform temperature control strategies can be adopted during chemical copper deposition to allow the metal to adhere more fully. Relying on these substrate pre-detection data, the probability of serious hidden bubble or hole wall delamination defects in high-density interconnection boards in the later stage can be reduced.

[0075] In an embodiment of the present application, the second frequency band acoustic wave is applied to the interface between the resin layer and the copper foil layer of the substrate according to the acoustic wave buffer stress data and the interlayer adhesion strength data, and the acoustic wave amplitude data and the acoustic wave phase difference data of the interface bonding part are recorded, comprising:

[0076] According to the acoustic wave buffer stress data, the acoustic wave action parameter is determined, and the first sub-frequency band acoustic wave corresponding to the acoustic wave action parameter is applied to the interface bonding part between the outer layer copper foil surface rough area and the adjacent resin layer of the substrate, and the acoustic wave scattering intensity data of the outer layer copper foil surface rough area is recorded;

[0077] According to the interlayer adhesion strength data, the acoustic wave penetration depth parameter is determined, and the second sub-frequency band acoustic wave corresponding to the acoustic wave penetration depth parameter is applied to the interface bonding part between the inner layer copper foil and the resin layer of the substrate in the high scattering area indicated by the acoustic wave scattering intensity data, and the acoustic wave attenuation data of the interface between the inner layer copper foil and the resin layer is recorded;

[0078] The amplitude value superposition processing is performed on the acoustic wave scattering intensity data and the acoustic wave attenuation data to form the acoustic wave amplitude data, and the phase superposition processing is performed on the acoustic wave scattering intensity data and the acoustic wave attenuation data to form the acoustic wave phase difference data.

[0079] The following describes the steps involved in the above embodiment:

[0080] When determining the acoustic wave action parameters according to the acoustic wave buffer stress data, the acoustic wave buffer stress curve obtained in the early stage needs to be combined with the material characteristics, so as to deduce the waveform frequency and pulse energy most suitable for the rough surface area of the outer copper foil. The acoustic wave action parameters include the transmission frequency, pulse width, output power and the like, which are used to ensure that the acoustic wave produces a sufficient and obvious scattering reflection difference on the rough metal surface. In implementation, an ultrasonic scanning system with multi-band output function can be used, the probe is coupled with the surface of the outer copper foil through water-based or oil-based coupling agent, and the first sub-band acoustic wave is transmitted point by point or line by line according to the parameters. The rough surface area of the outer copper foil refers to the part with large surface height difference caused by mechanical pressing or chemical etching in the manufacturing process. Under the irradiation of the acoustic wave, this area will have a higher scattering amount. The acoustic wave scattering intensity data is integrated by the receiving end according to the amplitude, time delay and spatial distribution of the echo signal. If the scattering intensity is obviously increased in some positions, it indicates that the surface roughness of this position is higher or there is particle accumulation. Through this process, the real acoustic reflection performance of the interface between the outer copper foil and the adjacent resin layer under different roughness conditions can be identified, and the basis for adjusting the transmission frequency and penetration mode when detecting the inner part in the subsequent process can be provided. When this step is adopted, if the transmission frequency is too low, the scattering contrast of the fine surface defects will be weakened; if it is too high, it will be easily submerged by the surface instantaneous reflection. Therefore, this sub-band is usually designed in the range that meets the scattering sensitivity of the outer copper foil surface and maintains sufficient penetration ability, for example, in the range of about 10 MHz to 15 MHz. By recording and processing the acoustic wave scattering intensity data, the voids or local unevenness caused by surface roughness can be more effectively quantitatively evaluated.

[0081] According to the interlayer bonding strength data, the acoustic wave penetration depth parameters are determined, and the results of the previous evaluation of the resin-metal adhesion condition are integrated. For example, if the copper foil in a certain area is not firmly combined with the resin, higher acoustic energy is used to ensure sufficient penetration. In this process, high scattering areas can be considered as parts where the surface has produced a large amount of scattered reflections. If the probe is continued to be detected at different angles or at a higher frequency, part of the energy can penetrate to the inner layer copper foil and resin layer interface. Therefore, in the high scattering area, the second sub-band acoustic wave corresponding to the acoustic wave penetration depth parameter is applied. The common setting method is to adjust the frequency to be slightly higher than the first sub-band (such as 15 MHz to 25 MHz), and adjust the pulse duration and transmission power so that it has better resolution for the inner layer position. If the inner layer copper foil and resin layer interface has uneven thickness, voids or delamination under this sub-band, the echo energy will be attenuated layer by layer and a recordable signal curve will be generated at the receiving end, which is called acoustic wave attenuation data. If the attenuation amplitude is too large, it means that the interface bonding strength is poor, or there are multiple interface scattering surfaces. For example, in a laminated structure, if the inner layer copper foil is the third layer, the resin and copper foil may be in a semi-peeling state due to uneven distribution of local fillers or hot pressing. After applying a higher frequency band, a continuous and obvious energy jump point can be detected, and the attenuation degree can be judged accordingly. Through this process, the differences in the adhesion of the inner and outer layers can be detected separately, and the penetration depth and scattering intensity are combined to distinguish whether there is only a surface roughness problem or a deep void problem. The design of the parameter range ensures that the high scattering surface of the outer layer will not be excessively reflected to cause signal saturation, and enough energy enters the inner layer so that the attenuation waveform can be accurately collected.

[0082] After the two scans of the first and second sub-frequencies are completed, the sound wave scattering intensity data and the sound wave attenuation data are obtained respectively. The amplitude superposition processing refers to performing point-by-point operation on the scattering intensity curve and the attenuation intensity curve in the amplitude direction in the same coordinate system, so as to synthesize a waveform which can better reflect the overall reflection energy distribution, and record it as the sound wave amplitude data. If the outer scattering peak and the inner attenuation peak overlap in a certain area, an obvious amplitude abnormal peak will appear after superposition, which can be used for preliminary positioning of the area which has both surface roughness and interface peeling risk. The phase superposition processing adopts a similar principle, and the scattering phase curve and the attenuation phase curve are superimposed point by point after the phase of the received signal is corrected, so as to obtain the sound wave phase difference data. If the phase jump directions of the two interfaces are consistent or the phase difference accumulates significantly, it indicates that the signal has multiple interface reflections and refractions in this area, and there is a high probability of interlayer cavity or delamination. By separating and then merging the amplitude and phase, the roughness change which only affects the energy attenuation and the structural gap which has a more significant effect on the phase can be distinguished. If only the amplitude is observed, some delamination defects may be misled by high scattering; if only the phase is observed, the subtle surface roughness is difficult to quantify. Therefore, the bidirectional superposition processing can clearly present the comprehensive characteristics of the outer roughness and the inner peeling, and form a set of more targeted sound wave amplitude data and sound wave phase difference data, which can provide reliable basis for further detection of temperature load or drilling process.

[0083] Please continue to refer to Figure 1 , according to the substrate pre-checking data, a short pulse multi-frequency acoustic wave is applied to the target hole area during the laser drilling process, the acoustic reflection signal at the drilling moment is recorded, and the local heat of the hole wall area is regulated to obtain the micro-hole acoustic reflection data;

[0084] In an embodiment of the present application, the substrate pre-checking data is used to determine the acoustic wave action range and the acoustic wave action time sequence of the target hole area, and a first frequency band short pulse acoustic wave corresponding to the acoustic wave action range and the acoustic wave action time sequence is applied to the target hole area, and the substrate acoustic reflection reference data before drilling is recorded.

[0085] According to the substrate pre-checking data, the acoustic wave action range and the acoustic wave action time sequence of the target hole area are determined, and a first frequency band short pulse acoustic wave corresponding to the acoustic wave action range and the acoustic wave action time sequence is applied to the target hole area, and the substrate acoustic reflection reference data before drilling is recorded.

[0086] According to the acoustic reflection reference data, a second frequency band short pulse acoustic wave is applied to the hole wall layer by layer during the laser drilling ablation process, and the sound wave amplitude mutation data and the phase shift data in each layer ablation process are recorded.

[0087] According to the amplitude mutation data of the sound wave, a first temperature control parameter is determined, a first local temperature gradient corresponding to the first temperature control parameter is applied to the hole wall region, and first hole wall temperature response data is recorded; according to the phase shift data, a second temperature control parameter is determined, a second local temperature gradient corresponding to the second temperature control parameter is applied to the hole wall region, and second hole wall temperature response data is recorded;

[0088] According to the first hole wall temperature response data and the second hole wall temperature response data, a third frequency band short pulse acoustic wave is applied to the hole wall, hole wall micro-crack acoustic scattering data and resin residual acoustic attenuation data are recorded, and the amplitude mutation data of the sound wave, the phase shift data, the first hole wall temperature response data, the second hole wall temperature response data, the hole wall micro-crack acoustic scattering data and the resin residual acoustic attenuation data are combined to form micro-hole acoustic reflection data.

[0089] The following specifically describes the steps involved in the above embodiments:

[0090] According to the substrate pre-check data, the sound wave action range and the sound wave action time sequence of the hole region are determined. The coordinate position corresponding to the target hole region, the possible defect distribution and the acoustic characteristics of the material in the region need to be identified in the existing substrate acoustic scanning results. When implementing, a series of transmission pulse parameters can be set in the control software of the ultrasonic detection device, including pulse frequency, pulse width and repetition time sequence, to ensure that the transmitted acoustic wave only covers the hole region to be processed. The first frequency band short pulse acoustic wave can be selected between 5MHz and 15MHz, and combined with the optimal incident angle and pulse energy determined in the early stage to avoid interference with adjacent regions during transmission. When the target hole region is subjected to the first frequency band short pulse acoustic wave, the acoustic detection device collects the echo signal before starting laser ablation, and forms the substrate acoustic reflection reference data before drilling based on parameters such as amplitude, phase and attenuation. If the reference data amplitude of a certain position is abnormally high or the phase jumps, it can be inferred that there is a local interface defect or internal material inhomogeneity. The first frequency band used in this step is usually not too high, so as to achieve stable penetration in a larger area and collect uniform reflection information. The consideration for this is to balance the resolution and penetration depth. When the material thickness and acoustic impedance difference are large, clear overall reflection distribution can be obtained through a lower frequency band, while avoiding missing possible shallow defects. Through this process, the initial acoustic state of the hole region can be obtained, which is convenient for dynamic comparison and judgment during the subsequent laser drilling process.

[0091] According to the above-mentioned acoustic reflection reference data, the second frequency band short pulse acoustic wave is applied to the hole wall layer by layer during the laser drilling ablation process. The method is to fix the ultrasonic probe on the adjustable support, keep a proper angle or adjacent arrangement with the laser processing head, so that the laser ablation and acoustic detection can be synchronized in the same hole area. The second frequency band is selected to be higher than the first frequency band, generally in the range of 15MHz to 30MHz, so as to more sensitively capture the material boundary between layers when the hole wall is ablated. With the laser layer by layer ablation of the resin or metal, the height of the hole wall surface will change and the material will separate, which will cause transient mutation in the amplitude and phase of the echo signal. The acoustic detection device records the collected echo signal in real time, and the amplitude mutation data can judge the ablation degree or edge roughness of each layer of material, and the phase offset data can identify the situation that the interlayer adhesion is not firm or the microcracks are expanding. For example, after drilling the outer copper foil, if there is local peeling between the resin layer and the copper foil, the phase jump will increase significantly. The sub-pulse timing in this step can be synchronized or asynchronously triggered according to the operating frequency of the laser, to ensure that the acoustic wave is applied for detection in time after each ablation is completed. The reason for selecting a higher frequency band is to improve the detection sensitivity to the subtle structural changes of the hole wall, and to make a more detailed distinction of the acoustic impedance difference between the material layers.

[0092] When determining the first temperature control parameter according to the amplitude mutation data of the acoustic wave, the position with significant amplitude jump in the previous step needs to be marked as the position where the material is more prone to local damage after being heated or stressed. The operator can place a micro heat source (such as a small area infrared heating plate) near the laser head or in the hole wall area, heat the corresponding position to the temperature gradient range corresponding to the first temperature control parameter within a set time, and then record the hole wall temperature response data through a thermal imager or a temperature sensor. If new cracks or significant material expansion deformation occur in the hole wall during the heating process, the amplitude curve of the acoustic wave echo will change again. When determining the second temperature control parameter according to the phase offset data, the idea is similar to the amplitude mutation, but it pays more attention to the possible inclined gap or adhesion anomaly in the deep layer of the material. If a large continuous offset is found in the phase detection stage, it means that the hole wall is prone to shear cracks under high and low temperature cycles, and the temperature gradient can be higher or lower, and the specific range can be selected in the range of 50℃ to 100℃ or larger. By recording the first hole wall temperature response data and the second hole wall temperature response data, the stress release and deformation law of the hole wall under the action of different thermal gradients can be understood, so as to determine which parts have a greater probability of producing hole wall defects.

[0093] According to the first hole wall temperature response data and the second hole wall temperature response data, a third frequency band short pulse acoustic wave is applied to the hole wall, which is mainly used to verify whether micro cracks have been formed after heating or cooling and whether resin remains. The third frequency band can be located at 30-50 MHz to capture higher resolution microstructure of the hole wall. In actual operation, the ultrasonic probe can be aimed at the target position of the hole wall, and a high-frequency short pulse is synchronously transmitted and the scattering and attenuation in the echo signal are recorded. If there are obvious micro cracks, the scattering peak value will be more concentrated and the amplitude will be higher; if the hole wall still has resin that has not been completely removed in this section, the echo will have a characteristic sticky tail in the attenuation mode. After the acoustic amplitude mutation data, the phase shift data, the first hole wall temperature response data, the second hole wall temperature response data, the hole wall micro crack acoustic scattering data and the resin residual acoustic attenuation data are collected, they can be normalized or layered mapped by data processing software to form a comprehensive micro hole acoustic reflection data. The comprehensive data can show the evolution process of the hole wall during laser processing and thermal excitation, and provide intuitive evaluation basis for fine hole wall quality of high-density interconnection board. If there are large scattering and significant attenuation in the data analysis results, special optimization needs to be performed in subsequent processes or repeated drilling to avoid potential bubble or hole wall peeling. In this way, the probability of forming blind holes or cavities in the later chemical deposition and electroplating process can be reduced, and the hole wall quality can meet the demand for high reliability of compact electronic products.

[0094] In one embodiment of the present application, the second frequency band short pulse acoustic wave is applied to the hole wall layer by layer during the laser drilling ablation process according to the acoustic reflection reference data, and the acoustic amplitude mutation data and the phase shift data during ablation of each layer are recorded, including:

[0095] The first sub-frequency band short pulse acoustic wave is applied to the ablation area of the outer copper foil according to the acoustic reflection reference data, and the metal layer acoustic reflection data and the copper foil residual distribution data during ablation of the outer copper foil are recorded;

[0096] The second sub-frequency band short pulse acoustic wave is applied to the alternating ablation area of the resin layer and the inner copper foil according to the metal layer acoustic reflection data, and the material peeling acoustic characteristic data and the resin decomposition acoustic characteristic data of the resin-metal interface are recorded;

[0097] The metal layer acoustic reflection data, the copper foil residual distribution data, the material peeling acoustic characteristic data and the resin decomposition acoustic characteristic data are combined and analyzed to form the acoustic amplitude mutation data and the phase shift data.

[0098] The following specifically describes the steps involved in the above embodiment:

[0099] According to the acoustic reflection reference data, when the first sub-band short pulse acoustic wave is applied to the ablation area of the outer copper foil, the acoustic distribution information of the surface of the outer copper foil needs to be obtained before laser processing, and the ablation range is calibrated in the control software. When implemented, a multi-frequency ultrasonic emission device can be used to send short pulse acoustic signals with a pulse frequency of 10 MHz to 15 MHz to the area where the outer copper foil may be affected by the laser, and the echo characteristics are recorded in real time at the receiving end. The metal layer acoustic reflection data reflects the echo intensity and phase of the copper foil at different depths and etching processes; the copper foil residual distribution data is calculated by the scanning system and is used to mark the metal debris or oxide layer that still exists after local ablation. If the metal layer acoustic reflection value of a certain area suddenly decreases, and the residual distribution value significantly increases, it indicates that loose copper foil debris is generated by laser etching at this place, which may affect the pore forming quality of the subsequent resin layer. The range of 10 MHz to 15 MHz is selected in this step to have high sensitivity to the metal surface and the ability to identify local micro defects, thereby helping to identify the metal integrity near the pore during the outer layer etching.

[0100] According to the obtained metal layer acoustic reflection data, when the second sub-band short pulse acoustic wave is applied to the alternating ablation area of the resin layer and the inner copper foil, the delamination or decomposition condition of the inner layer interface and the resin material needs to be monitored. When implemented, the transmission frequency can be adjusted to the range of 15 MHz to 25 MHz, and the pulse width and power are kept within the peak value range allowed by the system. The material peeling acoustic characteristic data of the resin-metal interface is identified by observing the multiple reflection peaks or phase anomalies with high amplitude in the echo, and if the peeling degree increases, the echo pattern will show discontinuity; the resin decomposition acoustic characteristic data can be judged by the characteristic peak shape when the resin is gasified or carbonized after the ablation temperature rises. For example, when the laser removes the resin layer by layer to contact the inner copper foil, if the receiving end monitors the significant embrittlement waveform in the resin, it indicates that the material has been carbonized or shrunk in a large area under thermal shock. The range selected in this step is higher than the first sub-band, which is to detect the deep layer resin and metal interface more delicately, so that the system can distinguish the material peeling state caused by outer layer etching and inner layer heating.

[0101] When the metal layer acoustic wave reflection data, copper foil residual distribution data, material peeling acoustic feature data and resin decomposition acoustic feature data are combined and analyzed, the amplitude and phase of each item of information can be matched in the same coordinate system through integrated software. If the outer layer copper foil residue and the inner layer material peeling occur at the same time in a certain area, and the resin decomposition is obvious, a sudden change in acoustic wave amplitude will be formed in the analysis result, which is manifested as a large fluctuation in echo intensity at local points. If the phase contrast shows that there are multiple jumps in the refraction path between the copper foil and the resin, there will be obvious abnormalities in the phase shift data. By comprehensively analyzing these characteristics, it can be accurately determined whether irreversible resin carbonization or interface cavitation occurs during the ablation process, so as to avoid hidden dangers in subsequent via plating. This process integrates the outer layer metal residue and the inner layer interface change into the same framework for evaluation, which can not only clearly determine the true progress of each ablation layer, but also better monitor the evolution of potential defects at different depths. This cross-layer data combination idea improves the control of the micro-hole forming quality of high-density interconnection boards, and provides accurate reference positioning for the hidden dangers of bubbles or voids in the subsequent chemical copper deposition and electroplating process.

[0102] Please continue to refer to Figure 1 Before the chemical copper deposition treatment, a plurality of regions on the board surface are independently temperature-controlled according to the micro-hole acoustic reflection data, and multi-frequency acoustic scanning data of the hole wall of each region under the excitation of a thermal pulse is recorded to form a regional acoustic feature map.

[0103] In an embodiment of the present application, before the chemical copper deposition treatment, a plurality of regions on the board surface are independently temperature-controlled according to the micro-hole acoustic reflection data, and multi-frequency acoustic scanning data of the hole wall of each region under the excitation of a thermal pulse is recorded to form a regional acoustic feature map, which includes:

[0104] Before the chemical copper deposition treatment, the board surface is divided into a plurality of temperature-independent control units according to the acoustic wave amplitude mutation region and the phase shift region in the micro-hole acoustic reflection data, and each temperature-independent control unit is provided with an independent temperature control parameter.

[0105] According to the temperature control parameters of each temperature-independent control unit, a first thermal pulse wave is applied to the hole wall of each region, and a first frequency band acoustic scanning wave is applied to the hole wall at the peak value of the first thermal pulse wave, and the acoustic scattering data caused by the transient expansion of the hole wall is recorded.

[0106] According to the acoustic scattering data, the stress response parameters of the hole wall of each region are determined, a second thermal pulse wave is applied to each temperature-independent control unit, and a second frequency band acoustic scanning wave is applied to the hole wall at the valley value of the second thermal pulse wave, and the acoustic attenuation data caused by the transient contraction of the hole wall is recorded.

[0107] According to the acoustic wave attenuation data, the strain distribution parameters of the hole wall of each region are determined, a third thermal pulse wave is applied to each temperature independent regulation unit, a third frequency band acoustic scanning wave is applied to the hole wall during the duration of the third thermal pulse wave, and acoustic characteristic data of the hole wall microcrack and cavity migration trend data are recorded;

[0108] The acoustic wave scattering data, the acoustic wave attenuation data, the hole wall microcrack acoustic characteristic data and the cavity migration trend data are combined according to the temperature independent regulation unit to form a regional acoustic characteristic map.

[0109] The following is a specific description of the steps involved in the above embodiments:

[0110] Before chemical copper deposition treatment, the board surface is divided into multiple temperature independent regulation units according to the acoustic wave amplitude mutation region and phase shift region in the micro-hole acoustic reflection data. The specific method is to first draw a micro-hole position and acoustic signal distribution map on the data processing platform, and mark the regions with sharp amplitude changes or obvious phase drift as high-risk sections. Subsequently, according to the material thickness and the layout of the board surface, these high-risk sections and the surrounding relatively stable sections are integrated into several independent temperature control units. Each temperature independent regulation unit is provided with independent temperature control parameters. A common way is to arrange a local heating module or an infrared radiation source below or on the side of the unit. If the acoustic wave amplitude mutation region is scattered, it can be divided into a group separately to accurately adjust the heating amplitude; if the phase shift region is continuous and concentrated, a higher or lower temperature range is set to cooperate with the time pulse scheme for heating or cooling. The reason for dividing multiple temperature units is to retain the margin for targeted adjustment of different defect types: amplitude mutation often indicates the presence of unevenness on the hole wall surface or near the surface layer, which may require a more moderate temperature gradient; phase shift is generally related to deep peeling or cavity formation, which requires a larger range or more intense temperature disturbance to reveal internal problems. In this way, when the next heat pulse is applied, appropriate temperature curves can be executed for different regulation units to obtain more recognizable acoustic feedback.

[0111] According to the temperature control parameters of each temperature independent unit, a first thermal pulse wave is applied to the region hole wall first, and a first frequency band acoustic scanning wave is applied at its peak moment. The first thermal pulse wave usually simulates the transient response of the hole wall under the medium temperature interval by short-time heating, and the common parameter range is a temperature rise of 60°C to 80°C, and the time is maintained for several seconds. The first frequency band acoustic scanning wave can be selected in the interval of about 10MHz to 15MHz, the acoustic probe is aimed at the target hole region and scanned at the peak of the thermal pulse, and the acoustic scattering data caused by the transient expansion of the hole wall is recorded. The scattering data is manifested as the change of echo intensity and waveform, and if the hole wall material produces a small amount of deformation or a small range of protrusion under thermal shock, the scattering peak will mutate. The reason for choosing the medium temperature interval is to facilitate the observation of the early stress distribution when the materials expand inconsistently, and the acoustic wave of 10MHz to 15MHz can balance the penetration and sensitivity. Through this process, it can be determined which regulation units have obvious material displacement or edge deformation after local heating, so as to infer the preliminary stress bearing capacity of the hole wall.

[0112] According to the acoustic scattering data, after determining the stress response parameters of the hole wall, a second thermal pulse wave is applied to the same temperature independent unit, and a second frequency band acoustic scanning wave is applied at its valley moment. This step mainly observes the transient contraction state of the hole wall during a certain degree of cooling or temperature drop, in order to capture whether the reverse stress release will cause new cracks or peeling. The parameter range of the second thermal pulse wave can be set to 40°C to 60°C or lower, so as to form a sufficient temperature difference with the peak temperature of the previous step, and then amplify the thermal retraction effect of the hole wall material. The second frequency band acoustic scanning wave is usually higher than the first frequency band, about 15MHz to 25MHz. Through this high frequency band scanning, smaller cracks or interface delamination can be captured at the moment of hole wall temperature drop, and the acoustic attenuation data caused by the transient contraction of the hole wall is recorded. If there are local embrittlement or microcracks in the hole wall, the attenuation curve will have obvious troughs or irregular delays in a short time. The reason for choosing to detect expansion first and then contraction is that some defects will only close or further tear at the cooling stage, so as to get different performances from the heating stage. By comparing the two acoustic curves, it can be determined which regulation units are more prone to produce fluctuations under cold and hot cycles, so as to further screen in the next stage.

[0113] According to the acoustic wave attenuation data, the strain distribution parameters of the hole wall of each region are determined, a third heat pulse wave is applied to each temperature independent regulation unit, and a third frequency band acoustic scanning wave is applied to the hole wall during the duration of the pulse to record the acoustic characteristic data of the hole wall microcrack and the cavity migration trend data. The third heat pulse wave is usually carried out at a high temperature of about 100°C or under rapid heating conditions, which can make the potential crack or pore appear relatively displacement faster. The third frequency band acoustic scanning wave can be selected in the range of 25MHz to 35MHz, focusing on detecting the acoustic anomalies of microcrack expansion and cavity gas transmission to the hole wall under high temperature stress. If the scattering peak of a certain section continues to increase or the echo phase is dislocated for many times after rising to high temperature, it indicates that the microcrack or cavity in the hole wall has obvious expansion or migration. The purpose of the high temperature stage is to further amplify the thermal expansion difference of defects in the material, so that even the cracks that are not detected at low temperature can be amplified and clearly captured in the acoustic scanning under high temperature conditions. Through this process, the final behavior of each temperature independent regulation unit under high temperature stress can be qualitatively and quantitatively recorded.

[0114] Finally, the acoustic wave scattering data, the acoustic wave attenuation data, the hole wall microcrack acoustic characteristic data and the cavity migration trend data are combined according to the temperature independent regulation unit to form a regional acoustic characteristic map. The map can be presented in a multi-layer superimposed or color contrast manner in the data analysis software, and different colors or marks represent the acoustic anomalies or defect distribution at different temperature stages. For example, if a certain unit has abnormal scattering at the first heat pulse and continues to expand at the second and third heat pulses, it can be considered as a high-risk section, and measures such as extending the deposition time or local reinforcement should be taken in chemical copper plating. For the units that are relatively stable at medium and high temperatures, they can be classified as low-risk areas, and the conventional process can be maintained during subsequent copper plating. Through the zoning combination of scattering and attenuation and other data, the dynamic evolution process of the hole wall defects at various temperature intervals can be analyzed, and the gradual diffusion path of the cavity from small to large can be further evaluated. As can be seen, by using the independent temperature control strategy and the acoustic scanning wave of different frequency bands, the overall investigation of the micro-hole wall of the HDI plate before chemical copper plating can be realized, the risk of bubble coating caused by micro-cavity or material layering in subsequent metallization can be reduced, and customized process parameter basis for subsequent electroplating is provided.

[0115] Please continue to refer to Figure 1 During the chemical copper plating process, according to the regional acoustic characteristic map, multi-frequency acoustic wave excitation is carried out on the hole region at a preset time interval, the acoustic reflection signal attenuation curve in the metal seed layer generation process is recorded, and the copper plating process monitoring data is obtained.

[0116] In one embodiment of the present application, in the process of chemical copper plating, according to the regional acoustic characteristic map, multi-band acoustic wave excitation is performed on the hole area at a preset time interval, the acoustic reflection signal attenuation curve in the process of metal seed layer generation is recorded, and the copper plating process monitoring data is obtained, including:

[0117] In the process of chemical copper plating, the copper plating monitoring time sequence of each hole area is determined according to the regional acoustic characteristic map and the preset time interval, the copper plating starting detection wave is applied to the hole area at the pause point of each copper plating monitoring time sequence, and the acoustic reflection characteristic data of the metal seed layer nucleation stage is recorded.

[0118] According to the acoustic reflection characteristic data, the copper plating growth detection wave is applied to different hole areas, and the metal grain growth distribution data and the interface bonding state data are recorded.

[0119] According to the metal grain growth distribution data and the interface bonding state data, the copper plating process detection wave is applied to the hole area, and the seed layer continuity change curve and the hole wall coverage change curve are recorded.

[0120] According to the preset time interval, the seed layer continuity change curve and the hole wall coverage change curve are dynamically analyzed, and the acoustic reflection characteristic data, the metal grain growth distribution data, the interface bonding state data and the dynamic characteristic analysis result are combined to form the copper plating process monitoring data.

[0121] The following is a specific description of the steps involved in the above embodiment:

[0122] When setting the copper plating monitoring time sequence of each hole area according to the regional acoustic characteristic map and the preset time interval, the hole wall information of high-risk, low-risk and moderate-risk in the acoustic characteristic map needs to be read in the data processing software first. The preset time interval refers to the time point at which the solution flow is paused every certain period in the chemical copper plating tank, so that the detection equipment can emit acoustic signals and collect echoes in a stable environment. When implementing, a set of electric valve control device can be installed on the chemical copper plating tank, and through the control signal synchronized with the scanning system, the solution circulation is closed at the corresponding period, so that the plating solution in the hole remains relatively static. At this time, the copper plating starting detection wave is emitted to the hole area, the pulse frequency is generally selected between 10MHz and 15MHz, and the acoustic reflection characteristic data of the metal seed layer nucleation stage is recorded at the receiving end. If an abnormal reflection peak is monitored in a certain hole area, it indicates that the adhesion or nucleation rate in this area is not uniform, and local stirring or prolonged copper plating time is required in subsequent operation. The key of this step is to ensure the monitoring accuracy of the copper plating starting stage, so as to identify whether the seed layer coverage is incomplete or the interface bonding is not firm.

[0123] According to the acoustic reflection characteristic data obtained in the previous step, a copper deposition detection wave can be applied to different hole regions to track the growth distribution and interface bonding state of metal grains on the resin hole wall. In practice, after the chemical copper deposition solution resumes flowing, it will provide a continuous copper ion deposition opportunity for the hole wall, and the acoustic probe will intermittently emit a detection wave to the target hole region at a pulse frequency of 15MHz to 25MHz, and the receiving end will obtain the echo changes during metal growth. If the copper grains on the hole wall are evenly distributed, the amplitude of the echo waveform will gradually increase over time and remain relatively smooth; if local agglomeration or voids occur, the echo curve may exhibit abnormal amplitude transitions at certain times. At the same time, the interface bonding state data is obtained based on the collection of attenuation coefficient and phase information, and if there is peeling between the deposited grains and the resin, the attenuation coefficient will increase sharply. In this way, unstable growth areas can be identified in real time and the corresponding process parameters can be adjusted in a timely manner, such as adjusting the local solution flow rate or adding auxiliary complex, so that the deposition process is more balanced. The purpose of doing this is to prevent stress concentration or micro-pore bubble risks on the hole wall caused by insufficient coverage in the early stage.

[0124] According to the metal grain growth distribution data and interface bonding state data, a copper deposition process detection wave can be applied to the target hole region to record the seed layer continuity change curve and the hole wall coverage change curve. The copper deposition process detection wave can be selected in the range of 25MHz to 35MHz to accurately capture the transition characteristics of grain growth from dispersion to continuous. The seed layer continuity change curve mainly monitors the coverage degree of the metal film on the hole wall by monitoring the echo amplitude and time delay, and once it appears stable rise and reaches the threshold value in a certain period, it means that the hole wall has a sufficient and complete metal layer. The hole wall coverage change curve is analyzed by partition algorithm, and if it is detected that the hole wall is still large area non-metal reflection, the coverage remains in a lower numerical value area, and additional extension of the copper deposition time or local strengthening of the stirring is needed to ensure that there is no risk of hole wall exposure in the subsequent electroplating stage. The above steps reflect the phased monitoring strategy, avoiding premature or late end of copper deposition, and ensuring that the metal adhesion of micro-pores and hole walls meets the established requirements.

[0125] According to the preset time interval, the dynamic characteristic analysis is performed on the seed layer continuity variation curve and the hole wall coverage variation curve, acoustic reflection characteristic data, metal grain growth distribution data, interface bonding state data and dynamic characteristic analysis results are combined to form copper plating process monitoring data. The implementation is that the acoustic waveform and derived parameters collected in the previous stages are input into a comprehensive analysis module, and by means of time sequence comparison and curve fitting method, the adhesion and growth uniformity of the same hole area at different time periods are extracted. If the waveform of a certain hole area remains stable and rising and the grain distribution dispersion is low under multiple pause detections, the copper plating process can be determined to be stable and safe; if the waveform of a certain hole area fluctuates or the phase mutates multiple times, the copper plating process monitoring data will automatically generate a warning prompt, prompting to take adjustment measures. The integrated data can be packaged and output, and further reference can be made in subsequent formal plating, realizing segmented adaptive process. Through this process, defects or uneven growth trends can be found in time before the seed layer is fully mature, so as to avoid the formation of covered micropores or poor adhesion areas in the hole wall in the later period, and to provide guarantee for the long-time stable work of the high-density plate of the notebook computer camera module.

[0126] Please continue to refer to Figure 1 In the plating process, according to the copper plating process monitoring data, periodic thermal excitation and fluid disturbance are applied to the plate surface, the propagation characteristics of multi-frequency acoustic waves in the plating solution are recorded, and plating dynamic monitoring data is obtained through adaptive signal processing;

[0127] In an embodiment of the present application, the plating process in which, according to the copper plating process monitoring data, periodic thermal excitation and fluid disturbance are applied to the plate surface, the propagation characteristics of multi-frequency acoustic waves in the plating solution are recorded, and plating dynamic monitoring data is obtained through adaptive signal processing, includes:

[0128] In the plating process, according to the seed layer continuity variation curve in the copper plating process monitoring data, a first plating thermal pulse is applied to the high-density micropore cluster area, and a second plating thermal pulse is applied to the peripheral trace area, and temperature gradient distribution data of the micropore area and the trace area are recorded;

[0129] According to the temperature gradient distribution data, a first fluid disturbance is applied to the high-density micropore cluster area, a second fluid disturbance is applied to the peripheral trace area, and a plating acoustic detection wave is applied to the deep and shallow micropore area under the action of the double fluid disturbance, and acoustic propagation attenuation data of different depth-diameter ratio micropores are recorded;

[0130] According to the acoustic propagation attenuation data, a low-frequency plating monitoring wave is applied to the high-density micropore cluster area, and a high-frequency plating monitoring wave is applied to the peripheral trace area, and micropore bottom current density distribution data and hole wall plating layer stress distribution data are recorded;

[0131] The current density distribution data is subjected to regional compensation operation, and the thickness distribution curve of the plating layer of the deep and shallow micropores is recorded. The plating layer stress distribution data of the hole wall is subjected to hierarchical processing, and the bubble migration characteristic curve of micropores with different depth-diameter ratios is recorded.

[0132] The plating layer thickness distribution curve and the bubble migration characteristic curve are subjected to adaptive signal filtering processing. The temperature gradient distribution data, the acoustic propagation attenuation data, the current density distribution data, the plating layer stress distribution data of the hole wall, the plating layer thickness distribution curve after adaptive signal filtering processing, and the bubble migration characteristic curve after adaptive signal filtering processing are combined to form electroplating dynamic monitoring data.

[0133] The following specifically describes the steps involved in the above embodiments:

[0134] According to the seed layer continuity change curve in the copper plating process monitoring data, it is necessary to identify which areas belong to high-density micropore clusters and which areas are mainly covered by traces. The specific method is to read the seed layer integrity information obtained in the previous stage, aggregate the closely distributed micropore areas into a block in the data visualization software, and mark them as high-density micropore cluster areas. Then mark the areas mainly covered by traces or large-area copper surfaces as peripheral trace areas. Based on this division, a first electroplating heat pulse is applied to the high-density micropore cluster area, and a second electroplating heat pulse is applied to the peripheral trace area. The first electroplating heat pulse is generally set in the range of 50°C to 70°C, so that the temperature of the plating solution in the cluster hole can be quickly raised, thereby improving the solution flowability and accelerating the chemical reaction in the hole. The second electroplating heat pulse can be slightly lower, such as between 40°C and 60°C, to ensure that the plating solution in the trace area maintains a temperature rising trend but does not cause local overheating. When performing this operation, a common method is to divide the electroplating tank into temperature control zones, so that the heaters in the corresponding areas work independently. By using temperature sensors or infrared thermometers to detect the board surface in these two different temperature intervals at the end of the heat pulse, the temperature gradient distribution data of the micropore area and the trace area can be obtained. If a steep gradient is detected in the high-density micropore cluster area, it indicates that the heat load in this area has significantly increased, and it is suitable for subsequent local disturbance enhancement or current density adjustment to avoid bubble accumulation at the hole bottom. The reason for setting different heat pulse intervals is that micropores and large-area traces have different temperature response requirements and need to be treated differently to improve the uniformity and quality stability of the finished product.

[0135] According to the obtained temperature gradient distribution data, a first fluid disturbance can be applied to the high-density micro-hole cluster region, a second fluid disturbance can be applied to the peripheral wiring region, and an electroplating acoustic detection wave can be emitted under the action of the double fluid disturbances. In practice, the electroplating tank is often equipped with a programmable stirring paddle or a bubble jet device, which can apply fluid disturbances of different intensities to specific partitions. The first fluid disturbance can be set to a higher flow rate or a more significant stirring frequency to allow the plating solution in the micro-hole region to flow quickly; the second fluid disturbance is relatively moderate to prevent excessive turbulence of the solution near the wiring from affecting the uniformity of the plated layer. In this state, an electroplating acoustic detection wave (10 MHz to 20 MHz adjustable) is emitted to the deep and shallow micro-hole regions, and the probe can be arranged above the board surface and scanned in real time through water-based coupling or electroplating liquid coupling. The acoustic propagation attenuation data is obtained by monitoring the echo energy and time delay. If there are larger bubbles or accumulated deposits in the holes, the acoustic attenuation will increase significantly, and the waveform will also have irregular oscillations. After recording these attenuation data, the flow guiding effects of different depth-diameter ratio holes under the action of double fluid disturbances can be compared, and abnormal deposition points caused by insufficient liquid injection at the local hole bottom can be identified. The reason for setting different fluid disturbance intensities is that deep holes rely more on high flow rate of the solution to carry away bubbles or residues than shallow holes, and excessive flow rate in the wiring area may cause uneven metal surface.

[0136] According to the acoustic propagation attenuation data, a low-frequency electroplating monitoring wave can be applied to the high-density micro-hole cluster region, a high-frequency electroplating monitoring wave can be applied to the peripheral wiring region, and micro-hole bottom current density distribution data and hole wall plated layer stress distribution data can be recorded. Low-frequency electroplating monitoring waves (such as 5 MHz to 10 MHz) have stronger penetration and recognition of large-scale defects in deep holes, which are beneficial to capture whether the current density at the bottom of the deep hole is too high or too low. If there are electroplating dead angles or protrusions at the bottom of the deep hole, the echo intensity and phase of this wave band will deviate rapidly from the normal value. High-frequency electroplating monitoring waves (such as 15 MHz to 25 MHz) are suitable for fine detection of the wiring area. If the plated layer stress at the edge of the wiring is too high or cracks are generated, the high-frequency signal attenuation and phase jump will increase significantly. In practice, a multi-frequency ultrasonic detection device can be used to scan the entire board surface in the order of low frequency first and then high frequency in the same measurement period, and the echoes are recorded in different time periods. If the current density in the deep hole is too large, a sharp peak will appear in the echo energy graph; if there are cracks in the wiring, local phase distortion will appear in the high-frequency data. The purpose of designing this low-frequency and high-frequency parallel idea is that different regions require different detection focuses. In order to quickly locate potential over-plating in deep holes or edge stress concentration phenomena, different wave bands need to be used to provide more reliable judgment basis.

[0137] The current density distribution data is subjected to regional compensation operation, the thickness distribution curve of the plating layer of the deep and shallow micro-holes is recorded, and the stress distribution data of the hole wall plating layer is subjected to hierarchical processing to obtain the bubble migration characteristic curve of the micro-holes with different depth-diameter ratios. The regional compensation operation refers to that, in the detection software, the high-density micro-hole cluster region is distinguished from the general hole region or the trace region, different reference current density models are set, and the difference correction is performed according to the actually measured time sequence curve. For example, if the current measured at the deep hole is high and is accompanied by large fluctuations, the corresponding error amount is subtracted in the subsequent calculation to obtain the thickness distribution closer to the actual plating layer growth rate. The stress distribution data of the hole wall plating layer can be obtained according to the stress measurement sensor or the stress calculation method based on the ultrasonic echo attenuation and phase characteristics. If there is a pressure gradient mutation in the hole or there is a bubble rising along the hole wall, it will present a unique curve impact form in the time sequence diagram. The bubble migration characteristic curve is formed, and it can help to judge whether there is a hidden cavity caused by the bubble being covered by metal or whether it is easy to diffuse in the subsequent high-temperature environment. The deep holes and shallow holes are thus split to more accurately evaluate the actual situation of each depth-diameter ratio in the electroplating process, rather than generally considering all holes as the same situation, thereby improving the capture rate of potential bubble problems.

[0138] The foregoing plating thickness distribution curve and bubble migration characteristic curve are subjected to adaptive signal filtering processing, and then the temperature gradient distribution data, acoustic propagation attenuation data, current density distribution data, hole wall plating layer stress distribution data, filtered plating thickness distribution curve and filtered bubble migration characteristic curve are combined to form electroplating dynamic monitoring data. The adaptive signal filtering processing can use common algorithms such as wavelet transform or adaptive harmonic decomposition to remove random noise and interference, and retain the stable signals generated by actual metal growth or bubble evolution. For example, the transient burr in the high-frequency monitoring wave time sequence due to stirring impact can be filtered out, and if the bubble persists in the hole, a repeatable peak or valley will be formed in the curve. Through the filtered curve combined with the previously recorded temperature and acoustic propagation attenuation information, a comprehensive judgment of the growth condition and stress distribution of each hole in different electroplating stages can be established, and presented in the form of data charts or three-dimensional visualization. In this way, the real-time monitoring and dynamic adjustment of the entire electroplating process can be effectively coordinated to avoid hidden dangers of good appearance but internal cavities, and also to maintain stability in subsequent high-temperature applications (such as long-time operation of laptop cameras). In summary, the design of these steps is based on the differentiated needs of high-density micro-holes and trace regions, process regulation is achieved through thermal pulse, fluid disturbance and multi-frequency acoustic detection, and data integration is performed by using programmable regional compensation and signal filtering algorithms, which greatly improves the detection rate and processing efficiency of bubbles and internal stress.

[0139] Please continue to refer to Figure 1After the electroplating is completed, the product is subjected to temperature cycle and stress excitation treatment according to the electroplating dynamic monitoring data, acoustic wave reflection data in the hole are recorded, and micro-via internal structure evaluation results are obtained through multi-dimensional data analysis.

[0140] In an embodiment of the present application, the micro-via internal structure evaluation results obtained through multi-dimensional data analysis after the electroplating is completed, the product is subjected to temperature cycle and stress excitation treatment according to the electroplating dynamic monitoring data, and the acoustic wave reflection data in the hole are recorded, including:

[0141] After the electroplating is completed, the micro-hole inner wall plating layer is evaluated according to the electroplating dynamic monitoring data, temperature cycle parameters and stress excitation parameters are determined, the product is subjected to first temperature cycle, and thermal cycle gradient data and cycle stress accumulation data of each micro-hole region are recorded;

[0142] According to the thermal cycle gradient data and the cycle stress accumulation data, the product is subjected to second temperature cycle, and the micro-hole inner wall is subjected to product evaluation acoustic wave, acoustic attenuation trend data and acoustic phase shift characteristic data in the micro-hole are recorded;

[0143] According to the acoustic attenuation trend data and the acoustic phase shift characteristic data, mechanical stress excitation is applied to the micro-hole, and structure deformation parameters and void evolution data of the micro-hole inner wall plating layer are recorded;

[0144] The thermal cycle gradient data, the cycle stress accumulation data, the acoustic attenuation trend data, the acoustic phase shift characteristic data, the structure deformation parameters and the void evolution data are comprehensively processed to form the micro-via internal structure evaluation results.

[0145] The following specifically describes the steps involved in the above embodiments:

[0146] After the electroplating is completed, the plated layer of the inner wall of the micro-hole is evaluated according to the electroplating dynamic monitoring data. The main method is to map the current density distribution, bubble migration trajectory and hole wall plating stress information of the previous stage into the coordinate system of the whole plate, and then separate the different depth-diameter ratio holes and adjacent trace areas for processing. By analyzing these parameters, the positions prone to cracks or blind areas at the bottom of the hole can be identified, so as to determine the subsequent temperature cycle parameters and stress excitation parameters. The first temperature cycle can be set as a rising and falling temperature process in the range of 50-70°C, and the multi-point thermocouple coupling monitoring of the micro-hole area of the finished product is carried out during the temperature rising or falling period. The thermal cycle gradient data is obtained by recording the instantaneous temperature difference between the hole wall surface and the inner layer through temperature sensors or infrared detection equipment, and the cycle stress accumulation data is calculated by stress detection modules or acoustic algorithms relying on micro-deformation sensing. If a group of holes has a significant thermal gradient rise and stress value accumulation in this temperature range, more stringent high-temperature tests are needed for subsequent tests to avoid cracks or voids in the hole caused by large temperature changes in this area.

[0147] According to the thermal cycle gradient data and the cycle stress accumulation data, the second temperature cycle is applied to the finished product, and the finished product evaluation sound wave is applied to the inner wall of the micro-hole to collect the acoustic attenuation trend data and phase shift characteristic data inside the micro-hole. The second temperature cycle is generally wider than the temperature range of the previous step, such as 60-100°C or higher, aiming to simulate the extreme thermal environment that may occur during the long-term operation of the notebook computer camera. The finished product evaluation sound wave can be emitted by a multi-frequency ultrasonic emission device, and the probe cooperates with the coupling agent to send high-frequency or medium-frequency pulse waves into the hole wall. The echo signal will be attenuated and phase-shifted at the junction of metal and resin due to micro-pores or defects. The attenuation trend data can reflect the bonding firmness of the metal layer during thermal expansion and contraction. If the air inside the micro-cavity is ionized during thermal diffusion, the echo energy will be significantly reduced. The phase shift characteristic data is related to the defect depth or delamination degree. If the hole wall has a slight tear, the echo phase will jump at this point. In this way, the second temperature cycle parameters are adjusted, which helps to truly evaluate the stability of the plated layer under larger thermal stress range.

[0148] According to the acoustic attenuation trend data and the phase shift characteristic data, mechanical stress excitation can be applied to the micro hole, and the structural deformation parameter and the void evolution data of the inner wall plating layer of the micro hole are recorded. The mechanical stress excitation mode includes configuring a vibration source on the back or side of the finished plate, so that the hole wall produces controlled deformation within a limited range, and the response of the acoustic signal to the external force impact is observed. The structural deformation parameter can be obtained by detecting the micro displacement of the hole wall when the probe and the vibration source are synchronized; the void evolution data is combined with the phase shift and attenuation change in the previous section to evaluate whether the coating bubble in the hole will continue to diffuse along the micro crack of the plating layer. For example, if the metal layer of the hole wall and the substrate have insufficient bonding, there will be instantaneous reflection enhancement or abnormal scattering distribution under stress excitation, and the process of hole movement or expansion in the hole diameter direction can be tracked in the detection software. This step focuses on the mechanical and acoustic coupling of the hole wall to ensure that the electrical connection is firm in harsh use environment.

[0149] The thermal cycle gradient data, cycle stress accumulation data, acoustic attenuation trend data, acoustic phase shift characteristic data, structural deformation parameter and void evolution data are comprehensively processed, and finally the internal structure evaluation result of the micro via is formed. The comprehensive processing can use a multi-dimensional data fusion algorithm to superimpose the acoustic test curves under different temperature intervals and stress intervals in the same coordinate system, and determine the distribution and failure mechanism of high-risk holes through trend comparison and abnormal clustering. If a certain hole area remains stable in multiple temperature cycles and mechanical excitation, it indicates that the plating layer and the substrate are well combined; if multiple parameters are detected to jump sharply, it indicates that the internal void or crack has entered an irreversible stage, and correction measures need to be taken in terminal screening or thickening processing. This dynamic evaluation in the finished state allows the HDI board of the notebook computer camera module to be fully verified in a large temperature difference and mechanical vibration environment to reduce the probability of intermittent connection failure during use. Combined with the subdivision analysis of each data, the goal of balancing high-precision detection and large-batch production capacity demand can be achieved.

[0150] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation made according to the inventive concept of the present application, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A HDI board manufacturing process for notebook camera module, characterized in that, The method comprises the following steps: performing multi-frequency acoustic wave penetration and temperature gradient treatment on the substrate to obtain acoustic response data and thermal response data of the substrate, and taking the acoustic response data and thermal response data as substrate pre-check data; applying short-pulse multi-frequency acoustic waves to a target hole region during laser drilling according to the substrate pre-check data, recording acoustic reflection signals at the moment of drilling, and performing local heat regulation on the hole wall region to obtain micro-hole acoustic reflection data; independently regulating the temperature of multiple regions on the board surface according to the micro-hole acoustic reflection data before chemical copper deposition, recording multi-frequency acoustic scanning data of the hole wall of each region under thermal pulse excitation to form a regional acoustic feature map; in the process of chemical copper deposition, according to the regional acoustic feature map, multi-frequency acoustic wave excitation is applied to the hole region at a preset time interval, the acoustic reflection signal attenuation curve in the process of metal seed layer generation is recorded, and copper deposition process monitoring data is obtained; in the process of electroplating, according to the copper deposition process monitoring data, periodic thermal excitation and fluid disturbance are applied to the board surface, the propagation characteristics of multi-frequency acoustic waves in the electroplating solution are recorded, and electroplating dynamic monitoring data is obtained through adaptive signal processing; after electroplating is completed, according to the electroplating dynamic monitoring data, temperature cycling and stress excitation treatment are performed on the finished product, acoustic wave reflection data in the hole are recorded, and micro-via internal structure evaluation results are obtained through multi-dimensional data analysis.

2. The HDI board manufacturing process for a laptop camera module according to claim 1, wherein, The method comprises the following steps: applying first frequency acoustic waves to the acoustic coupling medium layer arranged between the adjacent resin layers of the substrate, and recording acoustic wave buffer stress data and interlayer bonding strength data of the acoustic coupling medium layer; applying second frequency acoustic waves to the interface between the resin layer and the copper foil layer of the substrate according to the acoustic wave buffer stress data and the interlayer bonding strength data, and recording acoustic wave amplitude data and acoustic wave phase difference data of the interface bonding part; determining a first temperature interval range according to the acoustic wave amplitude data, applying a first temperature gradient to the substrate in the first temperature interval, and recording first thermal stress distribution data; determining a second temperature interval range according to the acoustic wave phase difference data, applying a second temperature gradient to the substrate in the second temperature interval, and recording second thermal stress distribution data; and performing acoustic scanning on the thermal stress concentration area through the acoustic coupling medium layer according to the first thermal stress distribution data and the second thermal stress distribution data, and recording acoustic feature data of the internal micro-cavity and interlayer bonding abnormal area of the substrate; performing stress compensation processing on the acoustic wave buffer stress data and the interlayer bonding strength data according to the thermal stress distribution data, and performing abnormal correction processing on the acoustic wave amplitude data and the acoustic wave phase difference data according to the acoustic feature data, and combining the data after compensation processing and correction processing to form substrate pre-check data.

3. The HDI board manufacturing process for a laptop camera module according to claim 2, wherein, The second frequency band acoustic wave is applied to the interface between the resin layer and the copper foil layer of the substrate according to the acoustic wave buffer stress data and the interlayer bonding strength data, and the acoustic wave amplitude data and the acoustic wave phase difference data of the interface bonding site are recorded, including: According to the acoustic wave buffer stress data, the first sub-frequency band acoustic wave corresponding to the acoustic wave action parameter is applied to the interface bonding site between the outer layer copper foil surface rough area and the adjacent resin layer, and the acoustic wave scattering intensity data of the outer layer copper foil surface rough area is recorded; According to the acoustic wave buffer stress data, the first sub-frequency band acoustic wave corresponding to the acoustic wave action parameter is applied to the interface bonding site between the outer layer copper foil surface rough area and the adjacent resin layer, and the acoustic wave scattering intensity data of the outer layer copper foil surface rough area is recorded; The acoustic wave scattering intensity data and the acoustic wave attenuation data are subjected to amplitude superposition processing to form acoustic wave amplitude data, and the acoustic wave scattering intensity data and the acoustic wave attenuation data are subjected to phase superposition processing to form acoustic wave phase difference data.

4. The HDI board manufacturing process for a laptop camera module of claim 1, wherein, The second frequency band short pulse acoustic wave is applied to the target hole area during laser drilling according to the substrate pre-check data, the acoustic reflection signal at the drilling moment is recorded, and the local heat of the hole wall area is controlled to obtain the micro-hole acoustic reflection data, including: According to the substrate pre-check data, the acoustic wave action range and the acoustic wave action time sequence of the hole area are determined, the first frequency band short pulse acoustic wave corresponding to the acoustic wave action range and the acoustic wave action time sequence is applied to the target hole area, and the substrate acoustic reflection reference data before drilling is recorded; According to the acoustic reflection reference data, the second frequency band short pulse acoustic wave is applied to the hole wall layer by layer during laser drilling ablation, and the acoustic wave amplitude mutation data and the phase shift data in each layer ablation process are recorded; According to the first temperature control parameter determined according to the acoustic wave amplitude mutation data, the first local temperature gradient corresponding to the first temperature control parameter is applied to the hole wall area, and the first hole wall temperature response data is recorded; according to the second temperature control parameter determined according to the phase shift data, the second local temperature gradient corresponding to the second temperature control parameter is applied to the hole wall area, and the second hole wall temperature response data is recorded; According to the first hole wall temperature response data and the second hole wall temperature response data, the third frequency band short pulse acoustic wave is applied to the hole wall, and the hole wall micro-crack acoustic scattering data and the resin residual acoustic attenuation data are recorded. The acoustic wave amplitude mutation data, the phase shift data, the first hole wall temperature response data, the second hole wall temperature response data, the hole wall micro-crack acoustic scattering data and the resin residual acoustic attenuation data are combined to form the micro-hole acoustic reflection data.

5. The HDI board manufacturing process for a laptop camera module of claim 4, wherein, The second frequency band short pulse acoustic wave is applied to the hole wall layer by layer during laser drilling ablation according to the acoustic reflection reference data, and the acoustic wave amplitude mutation data and the phase shift data in each layer ablation process are recorded, including: According to the acoustic reflection reference data, a first sub-frequency band short pulse acoustic wave is applied to the ablation area of the outer copper foil, and metal layer acoustic reflection data and copper foil residual distribution data in the ablation process of the outer copper foil are recorded; According to the metal layer acoustic reflection data, a second sub-frequency band short pulse acoustic wave is applied to the alternating ablation area of the resin layer and the inner copper foil, and material peeling acoustic characteristic data and resin decomposition acoustic characteristic data of the resin-metal interface are recorded; The metal layer acoustic reflection data, the copper foil residual distribution data, the material peeling acoustic characteristic data and the resin decomposition acoustic characteristic data are combined and analyzed to form acoustic wave amplitude mutation data and phase shift data.

6. The HDI board manufacturing process for a laptop camera module of claim 1, wherein, Before the chemical copper plating treatment, according to the micropore acoustic reflection data, temperature independent regulation is performed on multiple regions of the board surface, and multi-frequency acoustic scanning data of the hole wall in each region under thermal pulse excitation is recorded to form a regional acoustic characteristic map, including: Before the chemical copper plating treatment, according to the acoustic wave amplitude mutation region and the phase shift region in the micropore acoustic reflection data, the board surface is divided into multiple temperature independent regulation units, and an independent temperature control parameter is set for each temperature independent regulation unit; According to the temperature control parameters of each temperature independent regulation unit, a first thermal pulse wave is applied to the hole wall of each region, and a first frequency band acoustic scanning wave is applied to the hole wall at the peak value of the first thermal pulse wave, and acoustic scattering data caused by the transient expansion of the hole wall is recorded; According to the acoustic scattering data, the stress response parameters of the hole wall in each region are determined, a second thermal pulse wave is applied to each temperature independent regulation unit, and a second frequency band acoustic scanning wave is applied to the hole wall at the valley value of the second thermal pulse wave, and acoustic attenuation data caused by the transient contraction of the hole wall is recorded; According to the acoustic attenuation data, the strain distribution parameters of the hole wall in each region are determined, a third thermal pulse wave is applied to each temperature independent regulation unit, and a third frequency band acoustic scanning wave is applied to the hole wall during the duration of the third thermal pulse wave, and hole wall microcrack acoustic characteristic data and hole migration trend data are recorded; The acoustic scattering data, the acoustic attenuation data, the hole wall microcrack acoustic characteristic data and the hole migration trend data are partitioned and combined according to the temperature independent regulation unit to form a regional acoustic characteristic map.

7. The HDI board manufacturing process for a laptop camera module of claim 1, wherein, During the chemical copper plating process, according to the regional acoustic characteristic map, a multi-frequency band acoustic wave is excited to the hole area at a preset time interval, acoustic reflection signal attenuation curves in the metal seed layer generation process are recorded, and copper plating process monitoring data are obtained, including: During the chemical copper plating process, the copper plating monitoring time sequence of each hole area is determined according to the regional acoustic characteristic map and the preset time interval, the chemical copper plating solution flow is paused at the pause point of each copper plating monitoring time sequence, and a copper plating initiation detection wave is applied to the hole area, and acoustic reflection characteristic data of the metal seed layer nucleation stage are recorded; According to the acoustic reflection characteristic data, a copper plating growth detection wave is applied to different hole areas, and metal grain growth distribution data and interface bonding state data are recorded; According to the metal grain growth distribution data and the interface bonding state data, a copper deposition process detection wave is applied to the hole area, and a seed layer continuity change curve and a hole wall coverage change curve are recorded; According to the preset time interval, dynamic characteristic analysis is performed on the seed layer continuity change curve and the hole wall coverage change curve, and the acoustic reflection characteristic data, the metal grain growth distribution data, the interface bonding state data and the dynamic characteristic analysis result are combined to form copper deposition process monitoring data.

8. The HDI board manufacturing process for a laptop camera module of claim 1, wherein, In the electroplating process, according to the copper deposition process monitoring data, a periodic thermal excitation and a fluid disturbance are applied to the board surface, the propagation characteristics of multi-frequency acoustic waves in the electroplating solution are recorded, and electroplating dynamic monitoring data are obtained through adaptive signal processing, including: In the electroplating process, according to the seed layer continuity change curve in the copper deposition process monitoring data, a first electroplating thermal pulse is applied to the high-density micro-hole cluster area, and a second electroplating thermal pulse is applied to the peripheral wiring area, and the temperature gradient distribution data of the micro-hole area and the wiring area are recorded; According to the temperature gradient distribution data, a first fluid disturbance is applied to the high-density micro-hole cluster area, and a second fluid disturbance is applied to the peripheral wiring area, and an electroplating acoustic detection wave is applied to the deep and shallow micro-hole area under the action of the double fluid disturbance, and the acoustic propagation attenuation data of micro-holes with different depth-diameter ratios are recorded; According to the acoustic propagation attenuation data, a low-frequency electroplating monitoring wave is applied to the high-density micro-hole cluster area, and a high-frequency electroplating monitoring wave is applied to the peripheral wiring area, and the micro-hole bottom current density distribution data and the hole wall plating layer stress distribution data are recorded; The current density distribution data is subjected to regional compensation operation, the plating layer thickness distribution curve of deep and shallow micro-holes is recorded, and the hole wall plating layer stress distribution data is subjected to hierarchical processing, and the bubble migration characteristic curve of micro-holes with different depth-diameter ratios is recorded; The plating layer thickness distribution curve and the bubble migration characteristic curve are subjected to adaptive signal filtering processing, the temperature gradient distribution data, the acoustic propagation attenuation data, the current density distribution data, the hole wall plating layer stress distribution data, the plating layer thickness distribution curve after adaptive signal filtering processing and the bubble migration characteristic curve after adaptive signal filtering processing are combined to form electroplating dynamic monitoring data.

9. The HDI board manufacturing process for a laptop camera module of claim 1, wherein, After the electroplating is completed, according to the electroplating dynamic monitoring data, the finished product is subjected to temperature cycle and stress excitation processing, the in-hole acoustic wave reflection data are recorded, and the micro-via internal structure evaluation result is obtained through multi-dimensional data analysis, including: After the electroplating is completed, the micro-hole inner wall plating layer is subjected to regional evaluation according to the electroplating dynamic monitoring data, the temperature cycle parameters and the stress excitation parameters are determined, the first temperature cycle is applied to the finished product, and the thermal cycle gradient data and the cycle stress accumulation data of each micro-hole area are recorded; According to the thermal cycle gradient data and the cycle stress accumulation data, the second temperature cycle is applied to the finished product, and the finished product evaluation acoustic wave is applied to the micro-hole inner wall, and the acoustic attenuation trend data and the acoustic phase shift characteristic data in the micro-hole are recorded; According to the acoustic attenuation trend data and the acoustic phase shift characteristic data, mechanical stress excitation is applied to the micro hole, and structural deformation parameters and void evolution data of the inner wall coating of the micro hole are recorded; The thermal cycle gradient data, the cycle stress accumulation data, the acoustic attenuation trend data, the acoustic phase shift characteristic data, the structural deformation parameters and the void evolution data are comprehensively processed to form a micro-via internal structure evaluation result.

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