A method for detecting and identifying the location of internal voids in molded devices.

Abstract

This invention relates to the field of destructive physical analysis or failure analysis technology for molded components, and particularly to a method for detecting and identifying the location of internal voids in molded components. It addresses the problems of existing molded component inspection methods, such as high time consumption, limited observation range of the molded component's interior, and inability to accurately pinpoint the exact location of internal defects. The method for detecting and identifying the location of internal voids in molded components includes the following steps: performing acoustic scanning microscopy on the molded component to check for the appearance of black shadows in the image; if black shadows are present, performing X-ray inspection on the shadowed area to observe whether the molding compound forms an image with light and dark differences; if an image with light and dark differences is formed, performing laser decapsulation; observing whether voids are present, and recording the void location. This invention can accurately pinpoint the location of internal voids, improving the efficiency and accuracy of internal void location determination.

Description

Technical Field

[0001] This invention relates to the field of destructive physical analysis or failure analysis technology for molded components, and in particular to a method for detecting and identifying the location of internal voids in molded components. Background Technology

[0002] Molded components offer advantages such as low unit cost, small size, light weight, and mass production capability, leading to their increasing application and broad market prospects in today's miniaturized and lightweight electronic devices. However, molded components are non-hermetic and have a significant drawback: they are prone to moisture absorption. Especially when defects such as delamination, cracks, and voids exist within the molded component, moisture intrusion, coupled with rapid temperature changes during operation, can easily lead to failures such as moisture corrosion, the popcorn effect, and low-temperature delamination. This poses risks to the application of molded components, limiting their use to high-stress and high-reliability environments. Therefore, research into their defects is crucial.

[0003] The most common defects inside molded devices are delamination between interfaces, while cracks and voids are less common, and their size and precise location are difficult to determine. The main inspection items for molded device manufacturing processes include: external visual inspection → X-ray inspection → acoustic scanning microscopy inspection → internal visual inspection. Acoustic scanning microscopy mainly detects delamination between material interfaces within the molded device; it detects fewer voids and cracks within the molding compound, and the precise location of voids cannot be determined. X-ray inspection mainly detects foreign matter, voids, accumulation of fillers within the molding compound, and other structural defects. Delamination between material interfaces, voids, and cracks within the molding compound are difficult to detect with X-ray inspection, which has a resolution of approximately 1 μm.

[0004] Existing technologies provide relatively clear rejection criteria for delamination and voids in various parts of molded devices. However, current detection methods obtain two-dimensional images, which cannot accurately reproduce the internal morphology of the molded device and cannot directly confirm whether internal cracks or delamination meet the rejection criteria. For defects suspected of being cracks or voids detected by non-destructive methods, it is impossible to determine whether the defect location or size meets the rejection criteria. Existing technologies suggest sample sectioning for verification. Sample sectioning requires encapsulating the sample with epoxy resin, grinding and polishing it with sandpaper of different grits, and then observing it under a stereomicroscope and metallographic microscope, observing while grinding to locate the internal defect. However, this method is time-consuming, and the observation range of each section is limited, the observed defects are not intuitive, and it is easy to miss or misdetect them. During the curing, cutting, grinding, and polishing processes, stress may be generated inside the material. This stress may cause structural abnormalities or damage to the molded device, and this damage may be misjudged as the original defect of the sample.

[0005] Therefore, there is an urgent need for a method that can accurately detect internal voids in plastic-encapsulated devices and identify their precise locations. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide a method for detecting and identifying the location of internal voids in molded devices, in order to solve the problems of existing molded device detection methods being time-consuming, having a limited observation range inside the molded device, and being unable to accurately confirm the precise location of internal voids in the molded device.

[0007] The main objective of this invention is achieved through the following technical solution:

[0008] This invention provides a method for detecting and identifying the location of internal voids in molded devices, comprising the following steps:

[0009] Step 1: Perform acoustic scanning microscopy on the molded device to check for black shadows in the image;

[0010] Step 2: If a black shadow appears, perform an X-ray inspection on the black shadow area to observe whether the molding compound of the device forms an image with differences in brightness and darkness;

[0011] Step 3: If an image with contrasting light and dark areas is formed, perform laser desealing;

[0012] Step 4: Observe whether there are any cavities and record the location of the cavities.

[0013] Furthermore, step one includes: defining a three-dimensional world coordinate system to represent the orientation process of acoustic scanning microscopy detection, and performing acoustic scanning microscopy detection on the encapsulated device.

[0014] Furthermore, the three-dimensional world coordinate system is defined as follows: the center position of the molding compound is defined as the origin, the direction parallel to the major axis of the molding compound is defined as the X direction, the direction parallel to the minor axis of the molding compound is defined as the Z direction, the direction perpendicular to the major and minor axes of the molding compound is defined as the Y direction, and the plane of the molding compound is defined as the XZ plane; the acoustic scanning microscope inspection of the molding compound includes: using C mode to perform acoustic scanning microscope inspection on the XZ plane.

[0015] Furthermore, the acoustic scanning microscopy inspection of the XZ plane using C mode includes the following steps: Using C mode, acoustic scanning microscopy is performed on the XZ plane in the -Y direction to inspect the molding compound and the chip, the molding compound and the leadframe, and the molding compound and the substrate edge, obtaining clear scanning images of the corresponding interfaces by adjusting the time-of-flight (TOF) of the acoustic waves; Using C mode, acoustic scanning microscopy is performed on the XZ plane in the Y direction to inspect the molding compound and the substrate, and the molding compound and the leadframe, obtaining clear scanning images of the corresponding interfaces by adjusting the time-of-flight (TOF) of the acoustic waves; For chips mounted on heat sinks, acoustic scanning microscopy is performed on the bonding interface between the chip and the substrate in the XZ plane in the Y direction using C mode, obtaining clear scanning images of the corresponding interfaces by adjusting the time-of-flight (TOF) of the acoustic waves; and the areas showing black shadows in the acoustic scanning microscopy inspection images are identified.

[0016] Furthermore, step two includes: performing X-ray inspection on the encapsulated device in the X, Y, and Z directions respectively, observing whether the encapsulating material of the device forms an image with differences in brightness and darkness, and identifying the location of the brighter areas.

[0017] Furthermore, step three includes: performing laser etching on the surface of the encapsulated device that appears black during acoustic scanning microscopy and brighter during X-ray inspection, removing the encapsulating material layer by layer, observing the surface condition in real time, observing whether voids appear in the encapsulating material, and recording the location of the voids.

[0018] Furthermore, the process of laser etching the surface of the encapsulated device, which appears black during acoustic scanning microscopy and brighter during X-ray inspection, to remove the encapsulating material layer by layer, and observing the surface condition in real time to check for voids in the encapsulating material and record the location of the voids, includes: selecting a fiber laser laser opener, setting the opening speed, power, and frequency; confirming the opening window of the laser opener through images from X-ray inspection and acoustic scanning microscopy; setting the laser opener to continuous processing, setting the number of processing times to 1, and observing the morphology inside the device after removing the encapsulating material in the observation area of ​​the laser opener after each laser opening until voids are observed inside the encapsulating material.

[0019] Furthermore, the opening speed is 600 mm / s, the power is 30% of the maximum power of the laser opener, and the frequency is 30 kHz.

[0020] Furthermore, the opening window of the laser opener is confirmed by X-ray inspection and acoustic scanning microscopy, including: confirming the opening window of the laser opener by examining the chip, bonding wire, areas showing black shadows during acoustic scanning and areas showing bright colors during X-ray inspection.

[0021] Furthermore, after step four, the method further includes: comparing and analyzing the internal structural morphology of the device after acoustic scanning microscopy, X-ray inspection, and laser etching to remove the molding compound. If the void spans the internal bonding wire, such void is unacceptable.

[0022] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0023] 1. In the prior art, X-ray inspection and acoustic scanning microscopy inspection are not directly related. The two inspections are separate and observe different defects. This invention first uses acoustic scanning microscopy to check whether there are black shadows in the image, which provides a reference for X-ray inspection. The black shadow area detected by acoustic scanning microscopy is the focus of observation. The encapsulated device is re-examined in multiple directions with more detailed X-rays, which can clarify the more accurate location of cracks or voids.

[0024] 2. Existing sample cutting methods for molded devices are time-consuming, and the observation range of each section is limited. The observed defects are not intuitive and are prone to being missed or misdetected. This invention does not use the traditional sample cutting method to confirm whether the voids in the molding compound cross the bonding wire. Instead, it uses laser etching on the X / Z plane of the molded device in the Y direction to remove the molding compound layer by layer. This method can quickly observe the overall state inside the molding compound and facilitate the accurate confirmation of the location of the internal voids.

[0025] 3. Existing techniques require encapsulating the sample with epoxy resin, followed by layer-by-layer grinding and polishing with sandpaper to observe the internal morphology of a specific cross-section. This method necessitates first fixing the sample in a mixture of epoxy resin and curing agent, waiting for the liquid to solidify before grinding begins. During grinding, careful attention must be paid to the grinding speed and the choice of sandpaper to avoid grinding away defects due to excessive speed. Observation is required during grinding; if ground particles or scratches affect cross-sectional observation, polishing should be performed before further observation. If no defects are observed in the cross-section, grinding should continue, repeating this process to confirm the presence and precise location of internal defects. This invention utilizes laser etching to remove the encapsulating material, eliminating the need for epoxy resin sample preparation. The laser can directly remove the encapsulating material, and after removing one layer, the sample surface morphology can be directly observed through the magnifying window of the laser encapsulator, significantly improving the efficiency of determining internal void locations.

[0026] 4. Existing sample sectioning methods for confirming internal voids require grinding away the entire sample layer by layer, allowing only one cross-section to be observed at a time, thus reducing the three-dimensional observation of the sample. This invention, through laser etching, can precisely remove the molding compound without causing significant damage to internal bonding wires or other metals. Therefore, after removing the molding compound, the internal morphology of the sample can be clearly observed, facilitating confirmation of whether internal voids extend beyond the bonding wires and improving detection accuracy. Attached Figure Description

[0027] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0028] Figure 1 A flowchart of the method for detecting and identifying the location of internal voids in a plastic-encapsulated device provided by the present invention;

[0029] Figure 2 This is a schematic diagram of orientation detection for the plastic-encapsulated device in this invention;

[0030] Figure 3 This is a cross-sectional view of the encapsulated device in the Z direction in this invention;

[0031] Figure 4 For the present invention to Figure 3 A schematic diagram showing the laser opening window setup for laser etching at the location of the cavity;

[0032] Figure 5 This is an acoustic scanning microscope image of the internal cavity of the encapsulated device according to an embodiment of the present invention;

[0033] Figure 6 This is an X-ray perspective view of the internal cavity of the encapsulated device according to an embodiment of the present invention, taken in the Y direction.

[0034] Figure 7 This is an X-ray perspective view of the internal cavity of the encapsulated device according to an embodiment of the present invention;

[0035] Figure 8 This is an image of the internal cavity of the encapsulated device after laser opening, according to an embodiment of the present invention.

[0036] Figure label:

[0037] 01- Molding compound; 02- Pin; 03- Leadframe; 04- Chip; 05- Silver paste; 06- Substrate; 07- Bonding wire; 08- Void across the bonding wire; 09- Acoustic scanning microscope for detecting black shadows; 10- X-ray inspection of brighter areas; 11- Minimum laser opening window. Detailed Implementation

[0038] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0039] When defects such as delamination, cracks, and voids exist inside molded components, the inspection process typically involves external visual inspection → X-ray inspection → acoustic scanning microscopy → internal visual inspection to detect and determine whether the defects meet the rejection criteria of existing technology requirements. If the above inspection methods can determine that there are cracks or voids inside the molded component, and the cracks or voids cross the internal bonding wires, then the defect meets the rejection criteria. If accurate determination is not possible, the location of the internal defect is usually determined by sample sectioning. This inspection method is time-consuming, the observation range of each section is limited, the observed defects are not intuitive, and when the internal cracks or voids are small or perpendicular to the grinding section, resulting in fewer defects appearing on a certain section, it is easy to miss the observation of the defect.

[0040] The internal structure of a plastic-encapsulated device mainly includes: molding compound, leads, lead frame, chip, silver paste, substrate, and bonding wires. The bonding wires are used to connect the circuit chip to the lead frame, and the silver paste fixes the chip to the substrate and also provides conductivity.

[0041] To address the problems of existing methods for detecting molded components being time-consuming, having limited observation range within the molded component, and being unable to accurately pinpoint the location of internal voids, this invention provides a method for detecting and identifying the location of internal voids in molded components, comprising the following steps:

[0042] Step 1: Perform acoustic scanning microscopy on the molded device to check for black shadows in the image;

[0043] Step 2: If a black shadow appears, perform an X-ray inspection on the black shadow area to observe whether the molding compound of the device forms an image with differences in brightness and darkness;

[0044] Step 3: If an image with contrasting light and dark areas is formed, perform laser desealing;

[0045] Step 4: Observe whether there are any cavities and record the location of the cavities.

[0046] Specifically, in step one, the encapsulated device is inspected using an acoustic scanning microscope. First, a three-dimensional world coordinate system is defined to represent the orientation process of the acoustic scanning microscope inspection. The three-dimensional world coordinate system is defined as follows: the center position of the encapsulated device is defined as the origin, the direction parallel to the major axis of the encapsulated device is the X direction, the direction parallel to the minor axis of the encapsulated device is the Z direction, the direction perpendicular to the major and minor axes of the encapsulated device is the Y direction, and the plane of the encapsulated device is the XZ plane. The encapsulated device is inspected using the C mode, and the XZ plane is inspected using an acoustic scanning microscope. If black appears in the inspection image and the sound waves are lost, it may be that there are cracks or voids inside the encapsulation material.

[0047] Specifically, using C mode, acoustic scanning microscopy is used to inspect the molding compound and chip, molding compound and leadframe, and molding compound and substrate edge in the XZ plane in the -Y direction. By adjusting the time-of-flight (TOF) of the acoustic waves, clear scanning images of the corresponding interfaces are obtained, resulting in top views of the molding compound and chip, molding compound and leadframe, and molding compound and substrate edge.

[0048] Using C mode, acoustic scanning microscopy is used to inspect the molding compound and the substrate, and the molding compound and the leadframe in the Y direction of the XZ plane. By adjusting the time-of-flight (TOF) of the acoustic waves, clear scanning images of the corresponding interfaces are obtained, resulting in bottom views (referred to as rear views in the industry) of the molding compound and the substrate, and bottom views (referred to as rear views in the industry) of the molding compound and the leadframe.

[0049] For chips mounted on heat sinks, C mode is used to perform acoustic scanning microscopy on the bonding interface between the chip and the substrate in the Y direction of the XZ plane. By adjusting the time-of-flight (TOF) of the acoustic waves, a clear scanning image of the interface is obtained.

[0050] Acoustic scanning microscopy (AS / MS) utilizes the principle that sound waves must propagate through a medium to detect internal defects. For example, delamination at the interface between the molding compound and the leadframe, or cracks or voids within the molding compound, indicates a lack of medium at that location, preventing sound waves from propagating further. In AS / MS images, red or yellow indicates delamination, while white or gray indicates no delamination. Black shadows in the scanned image may be caused by: air bubbles on the surface of the molding compound during scanning; differences in the molding compound within that area compared to other areas; or cracks or voids within the molding compound. Visual inspection should first rule out air bubbles on the surface of the molding compound. Further observation and sectioning are needed to confirm the presence and location of cracks or voids within the molding compound, or whether there are differences in the molding compound in the shadowed areas.

[0051] Specifically, step two includes: performing X-ray inspection on the molded device in the X, Y, and Z directions respectively, observing whether the molding compound of the device forms an image with differences in brightness and darkness, and identifying the location of the brighter areas.

[0052] Generally, X-ray inspection of molded devices precedes acoustic scanning microscopy (AS / MS). However, X-ray inspection primarily detects foreign matter, voids, and accumulations of filler material within the molded device, as well as other structural defects. Since the molding compound itself absorbs relatively little X-rays, defects such as delamination at the interface of the molding material, voids, and cracks within the molding compound are difficult to detect with X-ray inspection, which has a resolution of approximately 1 μm, and therefore cannot provide a reference for the subsequent acoustic scanning microscopy inspection. Therefore, this invention adjusts the order of X-ray inspection and acoustic scanning microscopy inspection. If the acoustic scanning microscopy detects a dark shadow area in step one, as mentioned earlier, this area may contain cracks or voids. To confirm the more accurate location of the cracks or voids, the dark shadow area detected by the acoustic scanning microscopy is the focus of observation, and a more detailed X-ray inspection is performed again from multiple directions on the molded device to observe whether there are areas inside the molded device that are brighter than other areas due to a lack of molding compound.

[0053] X-ray transmission in the Y direction can clearly observe the location of the internal structure of the molded device. X / Z direction X-ray transmission can avoid various internal structures and more clearly observe whether there are differences in brightness in the areas where only the molding material exists. Brighter areas indicate that the molding material may be lacking, or there may be cracks or voids.

[0054] In the same inspection, acoustic scanning microscopy and X-ray examination are complementary methods. Acoustic scanning microscopy can identify potential cracks or voids in the dark shaded areas. Focusing on the dark shaded areas, the relevant parameters of X-ray examination are adjusted to conduct a more detailed inspection of the encapsulated device in the X, Y, and Z directions. It is observed whether there are areas that are brighter than other areas. If so, it indicates that the encapsulating material is lacking in that area, and there may be cracks or voids. Combining the results of acoustic scanning microscopy and X-ray examination can provide a clearer location of potential cracks or voids, providing a basis for the next step of sectioning to determine the exact location of cracks and voids.

[0055] Specifically, step three includes: performing laser etching on the surface of the encapsulated device that appears black during acoustic scanning microscopy and brighter during X-ray inspection, removing the encapsulating material layer by layer, observing the surface condition in real time, observing whether there are voids in the encapsulating material, and recording the location of the voids.

[0056] In the prior art, the rejection criteria for internal cracks and voids in molded devices are: cracks on the bonding wires; and any voids in the molding compound that cross the bonding wires. In this invention, the acoustic scanning microscope images of the molded device are a top view in the -Y direction and a bottom view in the Y direction (referred to in the industry as a rear view). Combined with X-ray inspection images, it is first confirmed whether the top and bottom views include the bonding wires. If a black shadow appears in the acoustic scanning microscope on the side including the bonding wires, the location of any potential internal defects needs to be accurately determined. In this invention, a laser decapsulator using a fiber laser is used to remove the molding compound layer by layer from the side with the black shadow.

[0057] Specifically, first, select a fiber laser opener, and set the parameters as follows: opening speed of 600mm / s, power of 30% of the maximum power of the laser opener, and frequency of 30KHz.

[0058] Secondly, the opening window of the laser decapsulator is confirmed through X-ray inspection and acoustic scanning microscopy. This should include: the chip, bonding wires, areas showing black shadows during acoustic scanning, and areas showing bright colors during X-ray inspection, for example... Figure 3 The location of the internal cavity in the device shown should be indicated by the laser opening window as follows: Figure 4 As shown;

[0059] Finally, the laser opener is set to continuous processing, and the number of processing times is set to 1. After each laser opening, the morphology inside the device after the molding compound is removed is observed in the observation area of ​​the laser opener until a void is observed inside the molding compound.

[0060] If the molded device is small and the magnifying window of the laser opener is insufficient to clearly see its internal structure, the device must be removed from the opener and observed under a microscope. If the abnormal area is not directly above the chip, and the laser opener reaches the bonding point above the chip but does not expose the void, the opening window should be reset to the area around the chip and extending to the outer bonding point. This is to prevent the laser opener from damaging the chip and making subsequent internal visual inspection impossible. Then, repeat the above steps until the void is found and it is confirmed that it crosses the bonding wire.

[0061] To determine whether the internal voids of a plastic-encapsulated device meet the rejection criteria, it is necessary to conduct a comprehensive comparative analysis of acoustic scanning microscopy images, X-ray inspection images, and the internal structural morphology of the device after laser removal of the encapsulant. If the voids extend beyond the internal bonding wires, such voids are unacceptable.

[0062] If the acoustic scanning microscope image shows a dark shaded area, and the X-ray image shows a brighter area directly above the bonding wire, but after laser desealing, no obvious void crossing the bonding wire is observed, and the bonding wire morphology is still not visible after removing the sealant, then the morphology after laser desealing can be recorded, and laser desealing can continue to confirm whether there is a void underneath. The sealant should be removed layer by layer until the exact location of the void is completely confirmed. If the acoustic scanning microscope image, X-ray image, and image of the void location after laser desealing all show that the void crosses the bonding wire, then this defect meets the rejection criteria and the product should be deemed unqualified.

[0063] To illustrate the feasibility of the technical solutions provided in the embodiments of the present invention, the following embodiments are given.

[0064] Example

[0065] Select PLCC packaged plastic devices manufactured by IDT and test them according to the detection and position identification method described in this invention.

[0066] Step 1: Perform acoustic scanning microscopy on the molded device to check for black shadows in the image. Figure 5 );

[0067] Step 2: Focusing on the black shadowed area that appeared in Step 1, perform X-ray imaging of the molded device in the Y, Z, and X directions. Observe whether the molding compound forms an image with light and dark differences. If light and dark differences can be observed, the more precise location of areas that may be voids inside can be further identified. Figure 6 and Figure 7 If no difference in brightness is observed in the molding compound, the cavity in the molding compound can only be preliminarily determined to be located on the front or back of the device based on the acoustic scanning image.

[0068] Step 3: Laser etching is performed on the surface of the molded device that appears black during acoustic scanning microscopy and brighter during X-ray inspection to remove the molding compound layer by layer. The surface condition is observed in real time to check for voids in the molding compound and the location of the voids is recorded. Figure 8 ).

[0069] Step 4: Compare and analyze the X-ray detection image, acoustic scan image, and internal structural morphology after laser removal of the molding compound to determine whether the void crosses the internal bonding wire.

[0070] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting and identifying the location of internal voids in plastic-encapsulated devices, characterized in that, Includes the following steps: Step 1: Perform acoustic scanning microscopy on the molded device to check for black shadows in the image; Step 2: If a black shadow appears, perform an X-ray inspection on the black shadow area to observe whether the molding compound of the device forms an image with differences in brightness and darkness; Step 3: If an image with contrasting light and dark areas is formed, perform laser desealing; Step 4: Observe whether there are any cavities and record the location of the cavities; Step one includes: defining a three-dimensional world coordinate system to represent the orientation process of acoustic scanning microscopy detection, and performing acoustic scanning microscopy detection on the plastic-encapsulated device; The three-dimensional world coordinate system is defined as follows: the center position of the molding compound is the origin, the direction parallel to the major axis of the molding compound is the X direction, the direction parallel to the minor axis of the molding compound is the Z direction, the direction perpendicular to the major and minor axes of the molding compound is the Y direction, and the plane of the molding compound is the XZ plane; Acoustic scanning microscopy inspection of molded devices includes: acoustic scanning microscopy inspection of the XZ plane using C mode; Step two includes: performing X-ray inspection on the molded device in the X, Y and Z directions respectively, observing whether the molding compound of the device forms an image with differences in brightness and darkness, and identifying the location of the brighter areas.

2. The detection and location recognition method according to claim 1, characterized in that, The acoustic scanning microscope inspection of the XZ plane using C mode includes the following steps: Using C mode, acoustic scanning microscopy is used to inspect the molding compound and chip, molding compound and leadframe, and molding compound and substrate edge in the Y direction of the XZ plane. By adjusting the time-of-flight (TOF) of the acoustic waves, clear scanning images of the corresponding interfaces are obtained, resulting in top views of the molding compound and chip, molding compound and leadframe, and molding compound and substrate edge. Using C mode, acoustic scanning microscopy is used to inspect the molding compound and the substrate, and the molding compound and the leadframe in the Y direction of the XZ plane. By adjusting the time-of-flight (TOF) of the acoustic waves, clear scanning images of the corresponding interfaces are obtained, resulting in bottom views of the molding compound and the substrate, and bottom views of the molding compound and the leadframe. For chips mounted on heat sinks, C mode is used to perform acoustic scanning microscopy on the bonding interface between the chip and the substrate in the Y direction of the XZ plane. By adjusting the time-of-flight (TOF) of the acoustic waves, a clear scanning image of the interface is obtained. Identify the areas with black shadows in the images detected by acoustic scanning microscope.

3. The detection and location recognition method according to claim 1, characterized in that, Step three includes: performing laser etching on the surface of the encapsulated device that appears black during acoustic scanning microscopy and brighter during X-ray inspection, removing the encapsulating material layer by layer, observing the surface condition in real time, observing whether there are voids in the encapsulating material, and recording the location of the voids.

4. The detection and location recognition method according to claim 3, characterized in that, The process of laser etching the surface of the molded device, which appears black during acoustic scanning microscopy and brighter during X-ray inspection, to remove the molding compound layer by layer, while observing the surface condition in real time, checking for voids in the molding compound, and recording the location of voids includes: Select a fiber laser laser opener and set the opening speed, power, and frequency; The opening window of the laser seal opener was confirmed by X-ray inspection and images detected by acoustic scanning microscope. The laser opener is set to continuous processing, and the number of processing times is set to 1. After each laser opener, the internal morphology of the device after removing the encapsulant is observed in the observation area of ​​the laser opener until a void is observed inside the encapsulant.

5. The detection and location recognition method according to claim 4, characterized in that, The opening speed is 600 mm / s, the power is 30% of the maximum power of the laser opener, and the frequency is 30 kHz.

6. The detection and location recognition method according to claim 4, characterized in that, The opening window of the laser opener is confirmed by X-ray inspection and acoustic scanning microscope images, including: confirming the opening window of the laser opener by examining the chip, bonding wire, black shadows that appear during acoustic scanning inspection, and bright areas that appear during X-ray inspection.

7. The detection and location recognition method according to claim 1, characterized in that, Step four is followed by: comparing and analyzing the acoustic scanning microscope images, X-ray inspection images, and the internal structural morphology of the device after laser etching to remove the molding compound. If the void spans the internal bonding wire, such void is unacceptable.

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