FCBGA package substrate slicing method and blind hole test analysis method

Abstract

The application provides an FCBGA packaging substrate slice manufacturing method and a blind hole test analysis method, including the following steps: providing an FCBGA packaging substrate to be tested, sampling a blind hole area on the packaging substrate to obtain a sample to be tested; performing chamfering processing and surface cleaning processing on the sample to be tested; forming a filling agent with a preset thickness on the blind hole area to form a filling layer filling the blind hole; performing vacuum drying processing on the sample to be tested after the filling layer is formed, so that the filling layer is solidified or coagulated; and sequentially performing glue filling, grinding and polishing processing on the sample to be tested to obtain an FCBGA packaging substrate slice. The application forms the filling layer filling the blind hole, improves the observation effect of the FCBGA packaging substrate slice under a sample preparation microscope, an optical microscope and SEM analysis, facilitates the distinction between the blind hole and the FCBGA packaging substrate base material, improves the manufacturing yield of the FCBGA packaging substrate slice, and realizes accurate test analysis on the blind hole.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, and in particular to a method for fabricating FCBGA package substrate slices and a method for testing and analyzing blind vias. Background Technology

[0002] Currently, blind via technology has been widely used in substrates to realize more functional applications of the substrates. As a key technology for realizing interlayer interconnection, blind via electroplating filling technology has also become one of the important research topics in the industry. However, with the development trend of electronic products towards high density and high precision, the diameter of blind vias in FCBGA package substrates is getting smaller and smaller, and the testing and analysis of these tiny blind vias is becoming more and more difficult.

[0003] The conventional testing and analysis method for blind vias on FCBGA packaged substrates typically involves sampling the substrate sample to be tested, applying adhesive, and then longitudinally grinding the slice until the blind via is reached. During grinding and polishing, the blind via location is usually observed under a low-magnification microscope before cross-sectional analysis. The cross-sectional analysis primarily involves longitudinally grinding the slice until the blind via is reached, and then precisely observing the location of the blind via under an optical microscope. For some micro-blind vias, focused ion beam (FIB) cutting technology is first used for cutting, followed by scanning electron microscopy (SEM) imaging to measure the upper and lower diameters, depth, and other relevant information of the blind via. The morphology of the cross-section is also subject to very high precision.

[0004] After drilling holes in the FCBGA package substrate and solder mask, if the diameter of the micro-blind vias is greater than 30μm, manual grinding and cross-sectioning allow for a relatively clear view under an optical microscope of whether the blind vias have been ground to their maximum diameter. This also allows for clear measurement and analysis of the required test data. However, when the diameter of the micro-blind vias in the substrate and solder mask is less than 30μm, it is not clear whether the maximum diameter of the blind via has been reached. This is because when the blind vias are very small, such as… Figure 1The diagram shows a structural schematic of an FCBGA package substrate slice, including blind via 01. Because both the substrate and solder mask appear grayish-black under low magnification in the sample preparation microscope, meaning the substrate and solder mask match the color of the micro-blind vias, it's impossible to quickly and clearly see the location of the micro-blind vias in the areas requiring observation. It also makes it impossible to confirm whether the vias have been ground to the required diameter. Furthermore, the boundary between the micro-blind vias and the substrate or solder mask is blurred, hindering a quick and clear view of the micro-blind vias' location and processing effectiveness. This results in long preparation times and inconsistent final preparation results for the micro-blind via slices. Additionally, when using FIB cutting and SEM for photographic analysis of blind via information, FIB cutting typically requires spraying tungsten or carbon deposition gases at the cutting site to protect the sample surface. Therefore, after cutting, the influence of the surface protective layer makes it difficult to analyze blind via information using SEM, and this can easily lead to ambiguity.

[0005] Therefore, there is an urgent need for a method to fabricate FCBGA package substrate slices that provides good observation results and high production yield. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for testing and analyzing blind vias of FCBGA packaged substrates, substrate slicing and fabrication method, to solve the problems of poor observation effect and low yield of FCBGA packaged substrate slices under sample preparation microscope, optical microscope and SEM analysis in the prior art.

[0007] To achieve the above and other related objectives, the present invention provides a method for fabricating an FCBGA package substrate slice, comprising the following steps:

[0008] A FCBGA package substrate to be tested is provided, and the blind via area on the substrate is sampled to obtain the test sample.

[0009] The sample to be tested is chamfered, and the surface of the sample to be tested after chamfering is cleaned.

[0010] A filling agent of a predetermined thickness is formed in the blind hole region to form a filling layer for filling the blind hole. The filling agent includes a conductive paste, a polymer solution containing phosphor, and a polymer containing metal particles.

[0011] The test sample after the filling layer is formed is placed horizontally in a vacuum dryer for vacuum drying to solidify or solidify the filling layer.

[0012] The sample to be tested is sequentially potted, ground and polished. During the polishing process, the filler layer is first polished to the position to be observed using mechanical polishing, and then a second polishing is performed using an ion polisher to obtain an FCBGA package substrate slice.

[0013] Optionally, the method for forming the filling agent includes scraping, spraying, screen printing, vacuum screen printing, 3D printing, and dispensing with a dispensing machine.

[0014] Optionally, the main components of the phosphor include luminescent substances that can automatically emit light in the dark.

[0015] Optionally, the conductive particles in the conductive paste include at least one of silver, copper, gold, nickel, carbon black, and graphite.

[0016] Optionally, the conductive paste may further include dimethyl carbonate, acetone, heptanedione, and propylene glycol methyl ether.

[0017] Optionally, the metal particles in the polymer containing metal particles include at least one of gold, silver, copper, aluminum, nickel, iron, palladium, and tin.

[0018] Optionally, the polymer containing metal particles may further include epoxy resin, polyacrylic acid, and polyurethane.

[0019] Optionally, there is no gap at the boundary between the sample to be tested and the glue-casting reagent after glue casting.

[0020] Optionally, grinding the sample to be tested includes the following steps: providing multiple sheets of sandpaper with different grits, grinding the sample to be tested in order of increasing grit, grinding the sample to be tested with each grit of sandpaper for a preset time, and rotating the sample to be tested by 90 degrees each time a new sheet of sandpaper is changed, so that the surface of the sample to be tested is ground until the blind hole area is exposed, and no scratches appear on the surface of the sample to be tested.

[0021] Optionally, the mechanical polishing of the sample to be tested includes the following steps: providing a mechanical polishing machine, adjusting the rotation speed of the polishing stage of the mechanical polishing machine to 100 r / min to 500 r / min, so that the cross-section of the sample to be tested to be polished is in contact with the polishing stage, and dripping polishing liquid with a particle size greater than 0.3 μm during the polishing process; then adjusting the rotation speed of the polishing stage to 100 r / min to 200 r / min, and dripping polishing liquid with a particle size less than 0.2 μm during the polishing process, until the polished cross-section of the sample to be tested shows no obvious scratches under an optical microscope.

[0022] Optionally, the polishing slurry includes aluminum oxide polishing slurry, silicon dioxide polishing slurry, and diamond polishing slurry.

[0023] Optionally, polishing the test sample using an ion mill includes the following steps: placing the mechanically polished test sample into the sample chamber of the ion mill, setting the accelerating voltage of the ion mill to 4kV~6kV, the ionization voltage to 1.5kV, the tilt angle of the sample stage to 5 degrees~15 degrees, the processing time to 5min~10min, and polishing the cross section of the test sample after evacuating the sample chamber.

[0024] This invention also provides a method for testing and analyzing blind vias on an FCBGA package substrate, comprising the following steps:

[0025] An FCBGA package substrate slice is provided, which is fabricated using the above-described method for fabricating an FCBGA package substrate slice.

[0026] The FCBGA packaged substrate is placed in the SEM sample chamber. After the vacuum level of the sample chamber reaches the preset vacuum level, the SEM electron beam is turned on to focus on the foreign matter on the surface of the sample to be tested. The SEM parameters are adjusted until the morphology of the blind hole in the slice of the FCBGA packaged substrate is clearly observed and photographed.

[0027] The blind vias were tested and analyzed based on the photographed cross-sectional images of the FCBGA package substrate.

[0028] As described above, the FCBGA package substrate slicing fabrication method and blind via testing and analysis method of the present invention have the following beneficial effects: By forming a filling reagent of a predetermined thickness in the blind via region and performing vacuum drying on the filling reagent, a filling layer for filling the blind via is formed. The formed filling layer is significantly different from the substrate of the FCBGA package substrate under sample preparation microscope, optical microscope, and SEM analysis. During the fabrication of the FCBGA package substrate slice, the substrate of the FCBGA package substrate and the blind via can be clearly distinguished. The measurement and analysis position of the blind via can be promptly detected under sample preparation microscope and optical microscope. At the same time, the processing effect of the sample under test can be quickly judged, i.e., whether it has reached the position close to the blind via, thus improving the observation effect and fabrication yield of the FCBGA package substrate slice. In the subsequent analysis and testing of the blind via using SEM, the blind via is not unclear due to FIB cutting, which facilitates the accurate measurement of the aperture and depth of the blind via in the FCBGA package substrate slice, thereby improving the testing and analysis efficiency and the accuracy of the analysis results. Furthermore, the filling reagent is low in cost and readily available. The filling reagent is processed using a vacuum drying method, which ensures that the filling reagent can enter the tiny holes or gaps in the blind via region to be tested. This facilitates the differentiation between the blind via and the substrate of the FCBGA package substrate, and makes it easier to test and analyze the FCBGA package substrate with small blind via diameters. It has high industrial application value. Attached Figure Description

[0029] Figure 1 The diagram shows a slice of an FCBGA packaging substrate.

[0030] Figure 2 The diagram shows a process flow chart of the FCBGA packaging substrate slice of the present invention.

[0031] Figure 3 The diagram shown is a structural schematic of a slice of the FCBGA packaging substrate of the present invention.

[0032] Figure 4 The diagram shows a parabolic structure of a slice of the FCBGA packaging substrate according to the present invention.

[0033] Figure 5 The diagram shows another polished structure of the FCBGA packaging substrate slice of the present invention.

[0034] Component designation explanation

[0035] 01 Blind Hole

[0036] 1. Blind hole

[0037] 2. Filling layer Detailed Implementation

[0038] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0039] Please see Figures 2 to 5 It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0040] Example 1

[0041] This embodiment provides a method for fabricating an FCBGA package substrate slice, such as... Figure 2 The diagram shown illustrates the fabrication process of the FCBGA package substrate slice, including the following steps:

[0042] S1: Provide an FCBGA package substrate to be tested, and sample the blind via area on the substrate to obtain the test sample;

[0043] S2: The sample to be tested is chamfered, and the surface of the sample to be tested after chamfering is cleaned.

[0044] S3: A filling agent of a predetermined thickness is formed in the blind hole region to form a filling layer for filling the blind hole. The filling agent includes a conductive paste, a polymer solution containing phosphor, and a polymer containing metal particles.

[0045] S4: The test sample after the filling layer is formed is placed horizontally in a vacuum dryer for vacuum drying treatment to solidify or solidify the filling layer;

[0046] S5: The sample to be tested is sequentially potted, ground and polished. During the polishing process, the filling layer is first polished to the position to be observed using mechanical polishing, and then a second polishing is performed using an ion polisher to obtain an FCBGA package substrate slice.

[0047] Specifically, in step S1, an FCBGA package substrate to be tested is provided, and the blind via area on the substrate is sampled to obtain the test sample.

[0048] Specifically, the method for sampling the blind via region on the substrate includes automatic slicing sampling, manual cutting sampling, or other suitable methods.

[0049] Specifically, when using an automatic slicer for sampling, the model of the automatic slicer can be selected according to the actual situation, provided that the quality of the sample to be tested is met, and there is no restriction here.

[0050] Specifically, while ensuring the analytical results, the size of the sample to be tested can be selected according to the actual situation, and there is no restriction here.

[0051] Specifically, the process of processing the sample under test to form the FCBGA package substrate slice also includes the step of observing the processing status of the sample under test using a sample preparation microscope and an optical microscope.

[0052] Specifically, provided that the processing of the sample to be tested can be clearly observed, the model and magnification of the sample preparation microscope can be selected according to the actual situation and are not limited here; the model and magnification of the optical microscope can be selected according to the actual situation and are not limited here.

[0053] Specifically, step S2 is performed to chamfer the sample to be tested and then clean the surface of the sample after chamfering.

[0054] Specifically, before chamfering the sample to be tested, the method also includes an edge processing step for the sample to be tested.

[0055] Specifically, the edge treatment method for the sample to be tested includes sanding or other suitable methods.

[0056] Specifically, edge processing of the sample to be tested can remove the burrs generated on the edge of the sample during sampling, making it easier to perform chamfering in the subsequent process.

[0057] Specifically, chamfering the sample to be tested can soften the angle of its edges and make the blind hole area easier to observe.

[0058] Specifically, while ensuring the fabrication of the FCBGA packaged substrate slices facilitates analysis, the size of the chamfer and the angle of the chamfer formed during the chamfering process of the sample under test can be selected according to the actual situation, and no restrictions are imposed here.

[0059] Specifically, the surface treatment method for the sample to be tested includes air purging or other suitable surface treatment methods.

[0060] Specifically, cleaning the surface of the sample to be tested includes using a hair dryer, air gun, or other suitable surface treatment tools.

[0061] Specifically, cleaning the surface of the sample to be tested can remove surface impurities and ensure the cleanliness of the blind hole area.

[0062] Specifically, step S3 is performed to form a filling agent of a preset thickness in the blind hole region to form a filling layer that fills the blind hole. The filling agent includes a conductive paste, a polymer solution containing phosphor, and a polymer containing metal particles.

[0063] As an example, methods for forming the filling agent include scraping, spraying, screen printing, vacuum screen printing, 3D printing, and dispensing with a dispensing machine.

[0064] As an example, the main components of the phosphor include luminescent substances that can automatically emit light in the dark.

[0065] Specifically, when phosphor is used as the filling agent, the main components of the phosphor include propylene, silicate, tungstate and luminescent material. As a luminescent coating that can automatically emit light in the dark, the yellow-green light emitted is the most bright.

[0066] As an example, the conductive particles in the conductive paste include at least one of silver, copper, gold, nickel, carbon black, graphite, or other suitable conductive particles.

[0067] As an example, the conductive paste may also include dimethyl carbonate, acetone, heptaacetone, propylene glycol methyl ether, or other suitable organic substances.

[0068] As an example, the metal particles in the polymer containing metal particles include at least one of gold, silver, copper, aluminum, nickel, iron, palladium, tin, or other suitable metal particles.

[0069] As an example, the polymer containing metal particles may also include epoxy resin, polyacrylic acid, polyurethane, or other suitable organic substances.

[0070] Specifically, when the filling agent fills the blind hole, the thickness of the filling agent can be selected according to the actual situation and is not limited here.

[0071] Specifically, provided that the quality of the FCBGA packaging substrate slices is met, the dosage of the filling reagent can be selected according to the actual situation, and there is no limitation here.

[0072] Specifically, in step S4, the sample to be tested after the filling layer is formed is placed horizontally in a vacuum dryer for vacuum drying treatment so that the filling layer is solidified or solidified.

[0073] Specifically, when the filling reagent is pretreated by vacuum drying, the pretreatment of the filling reagent includes the following steps: placing the test sample after the filling reagent of the preset thickness is formed into a vacuum dryer, setting the vacuum degree, drying temperature and holding time, and performing multiple vacuum treatments until the filling reagent is solidified or solidified to obtain the filling layer that fills the blind hole.

[0074] Specifically, provided that the filling reagent can solidify and fill the blind holes, the model of the vacuum dryer, the vacuum level, the holding time, the drying temperature, and the number of vacuum treatments can be selected according to the actual situation, and no restrictions are imposed here.

[0075] Specifically, the filling reagent is low in cost and readily available. Furthermore, the filling reagent is vacuum dried to ensure that it can enter the tiny holes or gaps in the blind via region to be tested. This facilitates the differentiation between the blind via and the substrate (i.e., dielectric layer) of the FCBGA package substrate, thereby enabling the testing and analysis of the FCBGA package substrate with blind vias of smaller diameter.

[0076] Specifically, in step S5, the sample to be tested is sequentially potted, ground, and polished. During the polishing process, the filler layer is first polished to the position to be observed using mechanical polishing, and then a second polishing is performed using an ion mill to obtain an FCBGA package substrate slice.

[0077] Specifically, the potting agent used for potting the test sample includes epoxy resin or other suitable potting agents.

[0078] Specifically, the methods for applying adhesive to the test sample include scraping, molding, or other suitable adhesive application methods.

[0079] Specifically, after potting the sample to be tested with adhesive, the process also includes a step of curing the potting agent.

[0080] As an example, there is no gap at the boundary between the test sample and the glue-filling reagent after glue application.

[0081] Specifically, there is no visible gap at the boundary between the sample to be tested and the glue-casting reagent after the glue is poured, so as to ensure the observation effect of the sample to be tested under an optical microscope.

[0082] Specifically, applying adhesive to the sample under test can fix the sample under test, protect other non-observation surfaces, and prevent the sample under test from being dragged and stretched and distorted during subsequent grinding.

[0083] As an example, grinding the sample to be tested includes the following steps: providing multiple sheets of sandpaper with different grits, grinding the sample to be tested in order of increasing grit, grinding the sample to be tested with each grit of sandpaper for a preset time, and rotating the sample to be tested by 90 degrees each time the sandpaper is changed, so that the surface of the sample to be tested is ground until the blind hole area is exposed, and no scratches appear on the surface of the sample to be tested.

[0084] Specifically, rotating the test sample 90 degrees with each sandpaper replacement can remove scratches, impurities, and contaminants from the surface of the test sample.

[0085] Specifically, provided that the blind hole area is exposed and no scratches appear on the surface of the sample to be tested, the grit of the sandpaper and the grinding time can be selected according to the actual situation and are not limited here.

[0086] Specifically, the surface of the test sample is ground to reduce scratches and impurities on the surface of the test sample, increase the flatness and cleanliness of the blind hole area on the surface of the test sample, and reduce the time required for subsequent polishing.

[0087] As an example, the mechanical polishing of the sample to be tested includes the following steps: providing a mechanical polishing machine, adjusting the rotation speed of the polishing stage of the mechanical polishing machine to 100 r / min to 500 r / min, so that the cross-section of the sample to be tested to be polished is in contact with the polishing stage, and dripping polishing liquid with a particle size greater than 0.3 μm during the polishing process; then adjusting the rotation speed of the polishing stage to 100 r / min to 200 r / min, and dripping polishing liquid with a particle size less than 0.2 μm during the polishing process, until the polished cross-section of the sample to be tested shows no obvious scratches under an optical microscope.

[0088] Specifically, the process of polishing the sample with a polishing agent also includes the step of observing the scratches on the surface of the sample using an optical microscope.

[0089] As an example, the polishing slurry includes aluminum oxide polishing slurry, silicon dioxide polishing slurry, and diamond polishing slurry.

[0090] As an example, the ion polishing of the sample to be tested includes the following steps: placing the mechanically polished sample to be tested into the sample chamber of the ion polisher, setting the acceleration voltage of the ion polisher to 4kV~6kV, the ionization voltage to 1.5kV, the tilt angle of the sample stage to 5 degrees~15 degrees, the processing time to 5min~10min, and polishing the cross section of the sample to be tested after evacuating the sample chamber.

[0091] Specifically, if obvious scratches are observed on the surface of the test sample after polishing using an optical microscope, the test sample can be further polished until the scratch density on the surface of the test sample is less than a preset value.

[0092] Specifically, provided that the cross-section of the blind hole area to be tested can be polished completely and no obvious scratches are observed under an optical microscope, the polishing time can be selected according to the actual situation and is not limited here.

[0093] Specifically, such as Figure 3 The image shown is a schematic diagram of the structure of a slice of the FCBGA packaging substrate. Figure 1 In contrast, it can be seen that when fabricating FCBGA package substrate slices with small-diameter blind vias, the blind vias are directly potted, ground, and polished after sampling, making it difficult to distinguish between the blind vias and the substrate of the FCBGA package substrate. When the blind via area of ​​the FCBGA package substrate slice is filled with the filling layer 2 that fills the blind via 1, it is easier to distinguish the blind via 1 and the substrate of the FCBGA package substrate, thus facilitating subsequent observation of the processing effect of the blind via 1.

[0094] Specifically, polishing the sample to be tested can remove the fine scratches generated during the grinding process, making it easier to observe the processing effect of the blind hole 1, thereby facilitating the accurate measurement of the blind hole diameter in the future.

[0095] Specifically, after the filling layer 2 is formed to fill the blind via 1, since the filling layer 2 is a conductive paste, a polymer solution containing phosphor, or a polymer containing metal particles, the material of the filling layer 2 is significantly different from the material and color of the FCBGA packaging substrate. During the preparation of the FCBGA packaging substrate slice, when the preparation microscope and optical microscope are used to observe the fabrication and processing of the FCBGA packaging substrate slice, the filling layer 2 and the substrate of the packaging substrate exhibit different gloss. Under the preparation microscope and optical microscope, the blind via 1 and the substrate of the FCBGA packaging substrate can be clearly observed and distinguished, thus improving the observation effect of the FCBGA packaging substrate slice under the preparation microscope and optical microscope.

[0096] Specifically, a filling reagent of a predetermined thickness is formed in the blind via region, and the filling reagent is vacuum dried to form the filling layer 2 that fills the blind via 1. The formed filling layer 2 is significantly different from the substrate of the FCBGA package substrate under a microscope and an optical microscope. The substrate of the FCBGA package substrate and the blind via 1 can be clearly distinguished. During the fabrication of the FCBGA package substrate slice, the measurement and analysis position of the blind via 1 of the FCBGA package substrate can be found in a timely manner under a sample preparation microscope and an optical microscope. At the same time, the processing effect of the sample to be tested (i.e., whether it has reached the position close to the blind via 1) can be quickly judged, which improves the observation effect and fabrication yield of the FCBGA package substrate slice under a sample preparation microscope and an optical microscope.

[0097] The method for fabricating an FCBGA package substrate slice in this embodiment involves forming a filling reagent of a predetermined thickness in the blind via region and then vacuum drying the filling reagent to form a filling layer 2 that fills the blind via 1. The formed filling layer 2 is significantly different from the substrate of the FCBGA package substrate under a sample preparation microscope and an optical microscope, clearly distinguishing the substrate from the blind via. During the fabrication of the FCBGA package substrate, the measurement and analysis position of the blind via 1 can be promptly detected under both microscopes, and the processing effect of the sample to be tested (i.e., whether it has reached the position close to the blind via 1) can be quickly determined, improving the observation effect of the FCBGA package substrate slice under a microscope and increasing the fabrication yield. Furthermore, the filling reagent is readily available and low in cost, and the vacuum drying method ensures that the filling reagent can enter the tiny pores or gaps in the blind via region to be tested, facilitating the testing and analysis of FCBGA package substrates with small blind via 1 diameters.

[0098] Example 2

[0099] This embodiment provides an FCBGA package substrate slice, which is fabricated using the FCBGA package substrate slice fabrication method described in Embodiment 1.

[0100] Specifically, the FCBGA package substrate slice includes a blind via region with blind vias, and the FCBGA package substrate slice has a chamfer and a filler layer 2 to fill the blind vias 1.

[0101] Specifically, the filler layer 2 includes a cured conductive paste, a polymer solution containing phosphor, and a polymer containing metal particles or other suitable materials.

[0102] Specifically, the size and thickness of the FCBGA packaging substrate slice can be selected according to the actual situation, provided that it facilitates accurate testing and analysis of the blind via 1, and there are no restrictions here.

[0103] Specifically, by forming the filling layer 2 that fills the blind via 1 in the FCBGA package substrate slice, the measurement and analysis position of the blind via 1 can be found in a timely manner under a sample preparation microscope and an optical microscope, which improves the fabrication yield and observation effect of the FCBGA package substrate slice and facilitates the accurate testing and analysis of the blind via 1.

[0104] In this embodiment, by forming the filling layer 2 that fills the blind vias 1 in the FCBGA package substrate slice, the measurement and analysis position of the blind vias 1 can be found in a timely manner under a sample preparation microscope and an optical microscope, which improves the fabrication yield and observation effect of the FCBGA package substrate slice and facilitates the accurate testing and analysis of the blind vias 1.

[0105] Example 3

[0106] This embodiment provides a method for analyzing blind vias in an FCBGA package substrate, including the following steps:

[0107] S1-1: Provides an FCBGA packaged substrate slice obtained by the method for fabricating an FCBGA packaged substrate slice as described in Embodiment 1.

[0108] S1-2: Place the FCBGA packaged substrate in the SEM sample chamber. After the vacuum level of the sample chamber reaches the preset vacuum level, turn on the SEM electron beam to focus on the foreign matter on the surface of the sample to be tested. Adjust the SEM parameters until the morphology of the blind hole in the slice of the FCBGA packaged substrate is clearly observed and photographed.

[0109] S1-3: The blind vias are tested and analyzed based on the slice images of the FCBGA package substrate obtained by taking pictures.

[0110] For details, please refer to Figures 4-5 Perform steps S1-1-S1-2 to provide an FCBGA packaged substrate slice prepared by the method described in Embodiment 1; place the FCBGA packaged substrate in the SEM sample chamber, and after the vacuum degree of the sample chamber reaches the preset vacuum degree, turn on the SEM electron beam to focus on the foreign matter on the surface of the sample to be tested, adjust the SEM parameters until the morphology of the blind hole 1 in the FCBGA packaged substrate slice is clearly observed and photographed.

[0111] Specifically, when scanning and photographing the blind via 1 in the slice of the FCBGA package substrate, the accelerating voltage of the SEM is set to 5kV to 30kV, and the beam current is set to 0.1nA to 0.2nA.

[0112] Specifically, such as Figure 4 The diagram shows a parabolic structure of the FCBGA package substrate slice. The process of taking pictures of the FCBGA package substrate slice using SEM also includes cutting the FCBGA package substrate slice using FIB cutting technology to expose the blind via 1.

[0113] Specifically, the FIB cutting technique is used to cut the FCBGA package substrate slice to expose the blind via 1, including the following steps: rotating the sample stage in the SEM to 50 to 54 degrees, adjusting the accelerating voltage to 30 kV, adjusting the beam current to 1 nA to 3 nA, and performing surface deposition on the sample to be tested; then adjusting the accelerating voltage to 20 kV to 30 kV, and the beam current to 15 nA to 50 nA for coarse cutting, and then using 3 nA to 10 nA for fine cutting until no obvious cutting marks are observed on the cross-section.

[0114] Specifically, provided that the test accuracy of the blind hole 1 is met, the model and imaging parameters of the SEM can be selected according to the actual situation, and no restrictions are imposed here.

[0115] Specifically, such as Figure 5 The diagram shows another parabolic structure of the FCBGA package substrate slice. By taking a picture of the blind hole of the FCBGA package substrate slice using SEM, the blind hole can be clearly observed, which facilitates the accurate measurement of the hole diameter and hole depth of the blind hole 1 in subsequent testing and analysis.

[0116] Specifically, steps S1-3 are performed to test and analyze the blind vias based on the slice images of the FCBGA package substrate obtained from the photograph.

[0117] Specifically, the testing and analysis of the blind hole 1 includes using the scale of an SEM to further accurately measure and analyze the diameter and depth of the blind hole 1.

[0118] Specifically, after the filling layer 2 is formed to fill the blind via 1, since the filling layer 2 is a conductive paste, a polymer solution containing phosphor, or a polymer containing metal particles, the material of the filling layer 2 is significantly different from the material and color of the FCBGA packaging substrate. When the blind via of the FCBGA packaging substrate slice is photographed and observed using SEM, the blind via and the substrate of the FCBGA packaging substrate can be clearly observed and distinguished under SEM. Furthermore, when the FCBGA packaging substrate slice is cut using FIB technology to expose the blind via 1, the filling layer 2 is also significantly different from the surface deposit used in the FIB technology, which can avoid the surface deposit causing the blind via 1 to be blurred, thus improving the observation effect of the FCBGA packaging substrate slice under SEM.

[0119] Specifically, the filling layer 2 is formed in the blind hole 1. When testing and analyzing the blind hole 1 using SEM, the FIB cutting step is simplified, the blind hole 1 is not blurred due to FIB cutting, and the detailed information of the hole wall and bottom of the blind hole is more easily observed, thereby improving the testing and analysis efficiency and accuracy of the blind hole 1.

[0120] The FCBGA package substrate blind via analysis method of this embodiment simplifies the FIB cutting step by forming the filling layer 2 that fills the blind via 1, avoids the blind via 1 being blurred due to FIB cutting, and facilitates the accurate measurement of the hole diameter and hole depth of the blind via 1 using SEM, thereby improving the testing and analysis efficiency and testing accuracy of the blind via 1.

[0121] In summary, the FCBGA package substrate slicing method and blind via testing and analysis method of the present invention form a filling reagent of a predetermined thickness in the blind via region and perform vacuum drying treatment on the filling reagent to form a filling layer for filling the blind via. The formed filling layer is significantly different from the substrate of the FCBGA package substrate under the sample preparation microscope, optical microscope, and SEM analysis. During the process of slicing the FCBGA package substrate, the boundary between the substrate of the FCBGA package substrate and the blind via can be clearly distinguished. Under the sample preparation microscope and optical microscope, the measurement and analysis position of the blind via of the FCBGA package substrate can be found in time, and the processing effect of the sample to be tested (i.e., whether it has reached the position close to the blind via) can be quickly judged, which improves the observation effect and manufacturing yield of FCBGA package substrate slices. When the blind via is subsequently analyzed and tested using SEM, the blind via is avoided from being blurred due to FIB cutting, which facilitates the accurate measurement of the position, diameter, and depth of the blind via in the FCBGA package substrate slice, thus improving the testing and analysis efficiency and the accuracy of the analysis results. Furthermore, the filling reagent is low in cost and readily available. The vacuum drying process ensures that the filling reagent can penetrate the tiny pores or gaps in the blind via region to be tested, facilitating the differentiation between blind vias and the substrate of the FCBGA package substrate. This also facilitates the testing and analysis of FCBGA package substrates with small-diameter blind vias. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0122] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for fabricating an FCBGA package substrate slice, characterized in that, Includes the following steps: A FCBGA package substrate to be tested is provided, and the blind via area on the package substrate is sampled to obtain the test sample. The sample to be tested is chamfered, and the surface of the sample to be tested after chamfering is cleaned. A filling agent of a predetermined thickness is formed in the blind hole region to form a filling layer for filling the blind hole. The filling agent includes a conductive paste, a polymer solution containing phosphor, and a polymer containing metal particles. The conductive particles in the conductive paste include at least one of silver, copper, gold, nickel, carbon black, and graphite. The blind hole includes a micro-blind hole with a pore size of less than 30 μm. The test sample after the filling layer is formed is placed horizontally in a vacuum dryer for vacuum drying to solidify or solidify the filling layer. The sample to be tested was sequentially potted, ground and polished. During the polishing process, the filler layer was first polished to the position to be observed using mechanical polishing, and then a second polishing was performed using an ion mill to obtain an FCBGA package substrate slice. The blind hole is photographed using a scanning electron microscope, and the blind hole is tested and analyzed, including measuring and analyzing the diameter and depth of the blind hole using the scale of the scanning electron microscope.

2. The method for fabricating an FCBGA package substrate slice according to claim 1, characterized in that: Methods for forming the filling agent include scraping, spraying, screen printing, vacuum screen printing, 3D printing, and dispensing with a dispensing machine.

3. The method for fabricating an FCBGA package substrate slice according to claim 1, characterized in that: The main components of the phosphor include luminescent substances that can automatically emit light in the dark.

4. The method for fabricating an FCBGA package substrate slice according to claim 1, characterized in that: The conductive paste also includes dimethyl carbonate, acetone, heptaacetone, and propylene glycol methyl ether.

5. The method for fabricating an FCBGA package substrate slice according to claim 1, characterized in that: The metal particles in the polymer containing metal particles include at least one of gold, silver, copper, aluminum, nickel, iron, palladium, and tin.

6. The method for fabricating an FCBGA package substrate slice according to claim 1, characterized in that: The polymer containing metal particles also includes epoxy resin, polyacrylic acid, and polyurethane.

7. The method for fabricating an FCBGA package substrate slice according to claim 1, characterized in that: There is no gap at the boundary between the sample to be tested and the glue-filling reagent after glue filling.

8. The method for fabricating an FCBGA package substrate slice according to claim 1, characterized in that: The grinding of the test sample includes the following steps: providing multiple sheets of sandpaper with different grits, grinding the test sample in order of increasing grit, grinding the test sample for a preset time with each grit of sandpaper, and rotating the test sample 90 degrees each time the sandpaper is changed, so that the surface of the test sample is ground until the blind hole area is exposed, and no scratches appear on the surface of the test sample.

9. The method for fabricating an FCBGA package substrate slice according to claim 1, characterized in that: The mechanical polishing of the test sample includes the following steps: providing a mechanical polishing machine, adjusting the speed of the polishing stage of the mechanical polishing machine to 100 r / min ~ 500 r / min, so that the cross-section of the test sample to be polished is in contact with the polishing stage, and dripping polishing liquid with a particle size greater than 0.3 μm during the polishing process; then adjusting the speed of the polishing stage to 100 r / min ~ 200 r / min, and dripping polishing liquid with a particle size less than 0.2 μm during the polishing process, until the polished cross-section of the test sample shows no obvious scratches under an optical microscope.

10. The method for fabricating an FCBGA package substrate slice according to claim 9, characterized in that: The polishing fluid includes aluminum oxide polishing fluid, silicon dioxide polishing fluid, and diamond polishing fluid.

11. The method for fabricating an FCBGA package substrate slice according to claim 1, characterized in that: Polishing the test sample using an ion mill includes the following steps: placing the mechanically polished test sample into the sample chamber of the ion mill, setting the acceleration voltage of the ion mill to 4 kV ~ 6 kV, the ionization voltage to 1.5 kV, the sample stage tilt angle to 5 degrees ~ 15 degrees, and the processing time to 5 min ~ 10 min, and polishing the cross section of the test sample after evacuating the sample chamber.

12. A method for testing and analyzing blind vias on an FCBGA package substrate, characterized in that, Includes the following steps: An FCBGA package substrate slice is provided, which is prepared by the method for preparing an FCBGA package substrate slice as described in any one of claims 1-11. The FCBGA packaged substrate is placed in the SEM sample chamber. After the vacuum level of the sample chamber reaches the preset vacuum level, the SEM electron beam is turned on to focus on the foreign matter on the surface of the sample to be tested. The SEM parameters are adjusted until the morphology of the blind hole in the slice of the FCBGA packaged substrate is clearly observed and photographed. The blind vias were tested and analyzed based on the photographed cross-sectional images of the FCBGA package substrate.

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