Waveform simulator, and ultrasound imaging device

Abstract

To provide a waveform simulator capable of obtaining a reflected wave from the desired boundary surface when radiating ultrasonic waves to a laminate of a target object that has multiple layer structures with boundary surfaces while easily setting the time gate.SOLUTION: A waveform simulator 10 includes: a first processing unit 1 that performs a series of first processing to calculate delay time from a point when a probe irradiates a laminate with ultrasonic waves until a point when the probe receives reflected waves from a target boundary surface based on layer structure information; a second processing unit 2 that performs a series of second processing to calculate a first transmittance from a point when the ultrasonic wave is output from the probe to a point when the same reaches the target boundary surface; a third processing unit 3 that performs a series of third processing to calculate the reflectance of the reflection of ultrasonic waves occurring inside a target laminate; and a fourth processing unit 4 that performs a series of fourth processing to calculate the second transmittance until the reflected wave reaches the probe from the target boundary surface.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a waveform simulator and an ultrasonic imaging device that simulate a reflected wave that is reflected and returned at a target interface indicating the bottom surface of a target laminated portion indicating a desired laminated portion when ultrasonic waves are irradiated onto a laminate having a plurality of layer structures.

Background Art

[0002] Generally, in order to detect a defect present in an inspection object having a plurality of layer structures by ultrasonic waves, the reflection characteristics due to differences in acoustic impedance are utilized. Ultrasonic waves propagate through liquid and solid substances, and reflected waves (echoes) are generated at the interfaces of substances having different acoustic impedances and at voids. Here, since the reflected waves from defects such as delamination and voids have a higher intensity than the reflected waves from non-defective areas, an image in which the defects present in the inspection object are made apparent can be obtained by imaging the reflection intensity at the bonding surface of each layer of the inspection object.

[0003] An ultrasonic imaging device scans an ultrasonic probe two-dimensionally in the horizontal direction and generates an image of a defect using the amplitude information and time information within a time gate (the time range of interest) of the reflected wave from the inspection target site within the inspection target. When there is a defect in the inspection target and a reflected wave derived from the defect exists within the time gate, a difference occurs between the reflected wave of the inspection target with the defect and the reflected wave of a sound inspection target without the defect, and it can be observed as a defect image.

[0004] The ultrasonic imaging device of Patent Document 1 has a time gate setting unit. The time gate setting unit receives as calculation models a defect-free calculation model in which no defect of the inspection target is set and a defective calculation model in which a defect is set, numerically simulates the ultrasonic waves propagating through the inspection target for each of the defect-free calculation model and the defective calculation model, and the time gate is at least a part of a time range in which the waveform of the ultrasonic wave obtained by the defect-free calculation model and the waveform of the ultrasonic wave obtained by the defective calculation model are different from each other.

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the device described in Patent Document 1, the propagation of ultrasonic waves can be obtained by numerical simulation using an existing simulator. However, in order to set the time gate, two types of models, a model without defects and a model with defects, must be prepared. In a state where it is unknown where the defect is, it was necessary to repeat mental errors in order to set the time gate.

[0007] Also, with an existing simulator, the entire waveform of the reflected wave can be obtained, but the relationship between the structural information and the temporal position where the reflected wave rises cannot be clearly grasped, and it is not possible to easily set the position of the time gate for a specific interface.

[0008] Therefore, an object of the present invention is to provide a waveform simulator and an ultrasonic imaging device that can obtain a reflected wave reflected from a desired interface when irradiating a laminate with ultrasonic waves so that a time gate can be easily set for an object to be inspected having a multi-layer structure with a plurality of inspection interfaces.

Means for Solving the Problems

[0009] To solve the above problems, the waveform simulator of the present invention is a waveform simulator that simulates a reflected wave that is reflected and returned at a target interface indicating the bottom surface of a target laminated portion indicating a desired laminated portion when ultrasonic waves are irradiated onto a laminate having a plurality of layer structures. The waveform simulator inputs layer structure information including the material and thickness of each laminated portion constituting the laminate, and based on the layer structure information and a material database, performs a first process of calculating a delay time from when the ultrasonic waves are irradiated from a probe onto the laminate until the probe receives the reflected wave from the target interface. The waveform simulator further includes a second processing unit that performs a second process of calculating a first transmittance from when the ultrasonic waves are output from the probe until they reach the target interface, a third processing unit that performs a third process of calculating a reflectance of reflections generated inside the target laminated portion, and a fourth processing unit that performs a fourth process of calculating a second transmittance from when the reflected wave reaches the probe from the target interface. Other aspects of the present invention will be described in the embodiments described below.

Advantages of the Invention

[0010] According to the present invention, when ultrasonic waves are irradiated onto a laminate, a reflected wave reflected from a desired interface can be obtained so that a time gate can be easily set for an object to be inspected having a plurality of layer structures with a plurality of inspection interfaces.

Brief Description of the Drawings

[0011]

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Embodiments for Carrying Out the Invention

[0012] The ultrasonic imaging device irradiates ultrasonic waves onto a semiconductor wafer or semiconductor package having a plurality of layer structures as an inspection object, acquires the reflected wave that the ultrasonic wave is reflected from the laminate and returns, checks the waveform of the reflected wave from the target interface which is the bottom surface of the target laminate portion showing the desired laminate portion, and is a useful tool for inspecting whether there are defects such as delamination and voids at the target interface.

[0013] When the laminate to be inspected consists of a large number of layers, the reflected wave has a waveform with multiple peaks in a continuous configuration because the reflected waves from each of the laminated parts that make up the laminate return. Therefore, when looking at the waveform to be inspected, a gate is set to extract that waveform. For example, when the object to be inspected is a laminate with a five-layer structure and the reflected wave with the bottom surface of the target laminated part being the third layer as the target interface is to be observed, the gate is set to include the peak part at a position surrounding the reflected wave from the target interface of the third layer.

[0014] This gate setting operation requires proficiency, and by facilitating the operation, it is possible to greatly improve the work efficiency.

[0015] When ultrasonic waves are irradiated on the laminate, the waveform simulator generates a simulated reflected wave that simulates the reflected wave from the target interface, supports the operation of setting an appropriate gate for the reflected wave from the target interface, enables quick operation without being affected by the proficiency of the operator, and greatly improves the inspection efficiency of the presence or absence of defects in the laminate.

[0016] <First Embodiment> FIG. 1 is a block diagram showing the configuration of a waveform simulator 10 according to the first embodiment. The waveform simulator 10 includes an input unit 9 that inputs layer structure information of the laminate, a material database 7 that stores information regarding the material, a first processing unit 1 (see FIG. 4) that performs a first process of calculating a delay time, a second processing unit 2 (see FIG. 5) that performs a second process of calculating a first transmittance, a third processing unit 3 (see FIG. 6) that performs a third process of calculating a reflectance, a fourth processing unit 4 (see FIG. 7) that performs a fourth process of calculating a second transmittance, a simulated signal generation unit 5 that generates a simulated signal, a waveform conversion unit 6 that generates a simulated reflected wave, and a waveform database 8 (storage unit) that stores the delay time and the simulated reflected wave.

[0017] The input layer structure information 22 includes what the material name (material) of each laminated part that makes up the laminate for which waveform simulation is to be performed is, and also how thick each laminated part is.

[0018] FIG. 2 is a diagram showing an example of the layer structure information 22. In the case of the laminated structure 21 in FIG. 2, the number of laminated layers is five (the first layer L1, the second layer L2, the third layer L3, the fourth layer L4, and the fifth layer L5), and further includes a liquid medium (usually water) that propagates the ultrasonic waves emitted from the ultrasonic probe 50 to the laminate.

[0019] The layer structure information 22 is configured to include a layer name, a material name, and a thickness. In this figure, the material names of the respective laminated portions are expressed as Material 1 and Material 2, but actually, epoxy resin, silicon, etc. are input. Note that the unit of thickness is mm.

[0020] FIG. 3 is a diagram showing the material database 7. The material database 7 stores the sound velocity and density with respect to the material names constituting the laminate. In the waveform simulator 10, the sound velocity and density of each laminated portion constituting the laminate are used in the process of generating the simulated reflected wave from the target interface. Therefore, the sound velocity and density of various material names are stored in the material database 7 in advance, and the sound velocity and density of each laminated portion are extracted from the material database using the material name of the layer structure information input from the input unit 9 as a key. Note that the unit of sound velocity is m / sec, and the unit of density is g / cm 3 is. Further, the material database 7 may include an acoustic impedance described later.

[0021] FIG. 4 is a diagram showing an example of calculating the delay time. FIG. 4 is a diagram related to the first process of calculating the delay time in the first processing unit 1. When the laminate is irradiated with ultrasonic waves, the ultrasonic waves propagate through each laminated portion and reach the substrate. In this propagation process, a propagation delay occurs. The delay time of each laminated portion can be calculated by the following formula. (Delay time) = (Thickness of the laminated portion) / (Sound velocity in the laminated portion) Since the propagation delay occurs in all laminated portions, the delay time that occurs up to the interface of the nth laminated portion can be calculated by the following formula.

[0022] [Number] Here, n is the number of layers up to the target interface, k is an integer variable from 0 to n, V is the speed of sound, and D is the thickness.

[0023] The propagation delay includes the delay that occurs until the ultrasonic wave emitted from the probe reaches the target interface and the delay that occurs until the reflected wave reflected at the target interface returns and reaches the probe. Therefore, finally, the delay time can be calculated by the following formula.

[0024] [Number]

[0025] FIG. 5 is a diagram showing an example of calculating the first transmittance. FIG. 5 is a diagram related to the second process of calculating the first transmittance in the second processing unit 2. When the ultrasonic wave reaches the target interface after being emitted from the ultrasonic probe 50, it attenuates when passing through the interface in front of the target interface. Therefore, for the ultrasonic wave before passing through a certain interface, the transmitted wave after passing through that interface has an amplitude multiplied by the transmittance of that interface. As shown in FIG. 5, for example, the transmittance related to the interface 1 between the stacked portion of the first layer and the stacked portion of the second layer can be calculated by the following formula.

[0026] (Transmittance) = (2Z2) / (Z1 + Z2) Here, Z represents the acoustic impedance of each stacked portion. Z can be calculated by Z = (speed of sound in the stacked portion) × (density of the stacked portion). Here, Z1 is the acoustic impedance of the stacked portion of the first layer L1, and Z2 is the acoustic impedance of the stacked portion of the second layer L2. Note that Z1 may be denoted as Z 1 and Zn may be denoted as Z n in some cases.

[0027] Ultrasonic attenuation occurs at each interface that the ultrasonic wave passes through, including the surface of the first layer L1, from the time the ultrasonic wave is emitted from the ultrasonic probe 50 until it reaches the target interface. Assuming the amplitude of the ultrasonic wave emitted from the ultrasonic probe 50 is Y, the transmittance of each interface is Tk, and the amplitude of the ultrasonic wave that has passed through and attenuated through each interface is Yk, when the number of layers of the laminate is 3, the amplitude of the transmitted wave attenuates as follows.

[0028] Y0 = Y × T0 Y1 = Y0 × T1 Y2 = Y1 × T2 Y3 = Y2 × T3 Here, T0 is the transmittance of the surface of the first layer L1, and Y0 is the amplitude of the transmitted wave that has passed through the surface of the first layer L1.

[0029] Therefore, the final transmitted wave Y3 can be calculated as follows. Y3 = Y × T0 × T1 × T2 × T3

[0030] Therefore, when the number of layers of the laminate is 3, if the overall transmittance from the time the ultrasonic wave emitted from the ultrasonic probe 50 reaches the target interface (interface 3) is defined as the first transmittance, then through the surface, interface 1, and interface 2, the first transmittance can be calculated by the following formula. (First transmittance) = T0 × T1 × T2

[0031] When the number of layers of the laminate is n, the first transmittance can be calculated by the following formula. (First transmittance) = T0 × T1 × ··· × (Tn - 1) (Equation 3)

[0032] Therefore, the first transmittance of the laminate with the number of layers n can be calculated by the following formula. (First transmittance) = (2 × Z1 / (Z0 + Z1)) × ··· × (2 × Zn / ((Zn - 1) + Zn) (Equation 4)

[0033] FIG. 6 is a diagram showing an example of calculating the reflectance. FIG. 6 is a diagram related to the third process of calculating the reflectance in the third processing unit 3. When the ultrasonic wave reaches the target laminated portion, reflection occurs between the target interface, which is the bottom surface portion of the target laminated portion, and the target upper surface portion, which indicates the upper surface portion of the target laminated portion. In the present embodiment, this reflection is simply referred to as reflection, and its reflectance is simply referred to as reflectance. Although the reflection will occur multiple times, here it is assumed that it occurs 5 times. Note that the number of reflections may be changed as necessary.

[0034] As shown in FIG. 6, there are 3 reflections from the target interface to the target upper surface portion and 2 reflections from the target upper surface portion to the target interface, for a total of 5 reflections. That is, the number of reflections from the target interface to the target upper surface portion is 1 more than the number of reflections from the target upper surface portion to the target interface.

[0035] When the acoustic impedance of the target laminated portion is Z2, the acoustic impedance of the previous laminated portion is Z1, and the acoustic impedance of the subsequent laminated portion is Z3, the first reflectance indicating the reflectance of the first reflection of the ultrasonic wave from the target interface to the target upper surface portion can be calculated by the following formula. (First Reflectance) = (Z3 - Z2) / (Z3 + Z2)

[0036] Also, the second reflectance indicating the reflectance of the second reflection of the ultrasonic wave from the target upper surface portion to the target interface can be calculated by the following formula. (Second Reflectance) = (Z1 - Z2) / (Z1 + Z2)

[0037] As described above, in the target laminated portion, since there are 3 first reflections and 2 second reflections, the overall reflectance can be calculated as follows. (Reflectance) = (First Reflectance) 3 ×(Second Reflectance) 2 = ((Z3 - Z2) / (Z3 + Z2)) 3 ×((Z1 - Z2) / (Z1 + Z2)) 2

[0038] Therefore, when the n-th layer lamination part is the target lamination part, it can be calculated by the following formula. (Reflectivity) = ((Zn + 1) - Zn)) / ((Zn + 1) + Zn)) 3 × ((Zn - 1) - Zn)) / ((Zn - 1) + Zn)) 2 (Equation 5)

[0039] FIG. 7 is a diagram showing an example of calculating the second transmittance. FIG. 7 is a diagram related to the fourth process of calculating the second transmittance in the fourth processing unit 4. In the propagation path from when the ultrasonic wave is emitted from the probe until it reaches the target interface and the reflected wave returns to the probe and is input to the probe, similar to the propagation path where the ultrasonic wave emitted from the probe reaches the target interface, it attenuates at each interface that transmits from the target interface to the probe until it reaches the probe. Therefore, similar to the first transmittance, by calculating the second transmittance indicating the transmittance from the target interface to the probe and multiplying it by the reflected wave reflected at the target interface, the amplitude of the reflected wave reaching the probe can be calculated.

[0040] When the number of laminations of the laminate is n and the acoustic impedance of each lamination part is Zk (k is a positive integer from 0 to n), the second transmittance can be calculated by the following formula. (Second transmittance) = (2 × Z0 / (Z0 + Z1)) × ··· × (2 × (Zn - 1) / ((Zn - 1) + Zn) (Equation 6)

[0041] As described above, the processes from the first processing unit 1 to the fourth processing unit 4 have been explained. However, regarding the process from when the ultrasonic wave emitted from the ultrasonic probe 50 is reflected at the target interface and returns to the ultrasonic probe 50 and is input, the waveform simulator processes as follows.

[0042] FIG. 8 is a flowchart showing the processing (S100) of the waveform simulator 10 according to the first embodiment. Refer to FIG. 1 as appropriate. The waveform simulator 10 first inputs, from the input unit 9, the lamination structure information of the laminate to be subjected to waveform simulation (S101). Specifically, regarding the lamination portions from the first layer to the nth layer, information regarding the material and thickness of each is input.

[0043] Next, for each lamination portion constituting the laminate, in the first processing unit 1 to the fourth processing unit 4, the first to fourth processes are executed, and the delay time and simulated reflected wave of each lamination portion are calculated and stored in the waveform database 8.

[0044] The processing will be specifically described. The waveform simulator 10 inputs the layer structure information (S101), sets the parameter n (number of laminations), and substitutes 1 as its initial value (S102). The waveform simulator 10 uses the material of the target lamination portion included in the input layer structure information as a search key with respect to the lamination portion corresponding to the parameter n as the target lamination portion, and extracts the sound velocity and density of the material from the material database (S103). The waveform simulator 10 uses the sound velocity, density, and thickness of these target lamination portions to execute the first to fourth processes in the first processing unit 1 to the fourth processing unit 4 (S104 to S107), and calculates the delay time, first transmittance, reflectance, and second transmittance for the target lamination portion.

[0045] Next, the waveform simulator 10 generates a simulation signal by the simulation signal generation unit 5 (S108). The simulation signal corresponds to the ultrasonic wave emitted from the probe in an actual ultrasonic imaging device. It is preferable to use the sinc function for the simulation signal to have a waveform shape close to that of an actual ultrasonic wave. Note that the sinc function is an elementary function obtained by dividing the sine function by its variable.

[0046] The waveform simulator 10 inputs the first transmittance, reflectance, second transmittance, and the simulated signal calculated by the above processing into the waveform conversion unit 6, multiplies the first transmittance, reflectance, and second transmittance to calculate the amplitude change rate (S109), and multiplies the simulated signal by the amplitude change rate to calculate the simulated reflected wave (S110). The waveform simulator 10 stores the delay time and the simulated reflected wave in the waveform database in association with the value of n of the target laminated portion (S111). (Simulated reflected wave) = Y × (First transmittance) × (Reflectance) × (Second transmittance) Here, Y is the simulated signal generated by the simulated signal generation unit.

[0047] While incrementing n, the waveform simulator 10 executes all the processes from the first process for all the laminated portions included in the input layer structure information, and repeats until the delay time and the simulated reflected wave are stored in the waveform database 8 (S112, S113).

[0048] In the actual operation of setting gates for the reflected waves from each interface constituting the laminate using the ultrasonic imaging device, it may be performed as in the second embodiment. Before the actual operation, waveform simulation by the waveform simulator is executed to store the delay time and the simulated reflected wave for each laminated portion in the waveform database. In the actual operation, the delay time and the simulated reflected wave for each laminated portion stored in the waveform database are called, and a time gate (gate) is set around the simulated signal.

[0049] In this way, by using the waveform simulator 10, it is possible to easily and accurately set time gates for each laminated portion without being affected by the skill level of the operator.

[0050] <Second Embodiment> The second embodiment will describe an ultrasonic imaging device 100 incorporating the waveform simulator 10 of the first embodiment. FIG. 9 is a diagram showing the configuration of the ultrasonic imaging device 100 according to the second embodiment. The ultrasonic imaging device 100 includes a waveform simulator 10 including a material database 7 and a waveform database 8, an ultrasonic probe 50, a probe driving unit 40 for driving the ultrasonic probe 50, and a control device 30. The control device 30 includes an input unit 9, a scanning control unit 31 for controlling the scanning of the probe driving unit 40, a gate information input unit 32, a transmission / reception control unit 33 for exchanging signals with the probe, a gate setting unit 34, an image generation unit 35, and a display unit 36. Note that the input unit 9 is shared by the ultrasonic imaging device and the waveform simulator.

[0051] The ultrasonic imaging device 100 irradiates ultrasonic waves at irradiation points set at a predetermined interval via the ultrasonic probe 50 within the inspection range of the object to obtain the reflected waves, extracts an interface echo indicating the waveform of the bonding interface to be inspected from among the reflected waves, converts the signal intensity of the interface echo into a positive integer value (0 to 255) to generate pixelated information, performs the above processing on all irradiation points or specific irradiation points, and generates an image of the bonding interface based on the generated pixelated information of the irradiation points to detect defects.

[0052] The ultrasonic probe 50 includes an encoder 51 for detecting the scanning position of the ultrasonic probe 50 and a piezoelectric element 52 for mutually converting an electrical signal and an ultrasonic signal. The piezoelectric element 52 is, for example, a single-focus type ultrasonic sensor.

[0053] The control device 30 includes an input unit 9, a scanning control unit 31 for controlling the scanning of the probe driving unit 40, a gate information input unit 32, a transmission / reception control unit 33 for exchanging signals with the probe, a gate setting unit 34, an image generation unit 35, and a display unit 36. Note that the input unit 9 is shared by the ultrasonic imaging device 100 and the waveform simulator 10.

[0054] The probe driving unit 40 controls the scanning position of the ultrasonic probe 50 by a mechanical control unit 41, an X-axis scanner 42, a Y-axis scanner 43, and a Z-axis scanner 44, and the mechanical control unit 41 receives the current scanning position information of the ultrasonic probe 50.

[0055] The piezoelectric element 52 has electrodes attached to both surfaces of a piezoelectric film, and is composed of zinc oxide (ZnO), ceramics, a fluorine-based copolymer, or the like. When a voltage is applied between both electrodes, the piezoelectric element 52 transmits ultrasonic waves from the piezoelectric film. Further, the piezoelectric element 52 converts the echo wave (received wave) received by the piezoelectric film into a received signal, which is a voltage generated between the both electrodes.

[0056] Water 61 is injected into the water tank 60, and the subject 62 is placed in a submerged state in the water 61. The water 61 in the water tank 60 is a liquid substance, which is a propagation medium necessary for efficiently propagating the ultrasonic waves radiated from the opening surface at the lower end of the ultrasonic probe 50 (ultrasonic transducer) into the subject 62. The subject 62 is, for example, a semiconductor wafer or a semiconductor package having a plurality of layer structures.

[0057] The ultrasonic probe 50 is immersed in the water 61 filled in the water tank 60 and is arranged so as to face the upper part of the subject 62 in the Z direction at a predetermined distance.

[0058] The probe driving unit 40 can freely move the ultrasonic probe 50 in the XYZ directions. For example, while irradiating the subject 62 with ultrasonic waves, the ultrasonic probe 50 scans in the X-axis direction from the starting point (one end point) to the end point (the other end point) of the subject 62 at a predetermined speed. When the ultrasonic probe 50 reaches the end point, the probe is moved by a predetermined amount in the Y-axis direction and scans in the X-axis direction from the viewpoint to the end point in the opposite direction at a predetermined speed.

[0059] Based on this movement operation, the ultrasonic probe 50 scans a predetermined measurement range on the surface of the subject 62, transmits ultrasonic waves, receives reflected echo waves at a plurality of preset measurement points within the measurement range, and can visualize and inspect defects in the internal structure included in the measurement range.

[0060] The ultrasonic imaging device 100 is an ultrasonic imaging device including a waveform simulator 10 and a display unit 36. The layer structure information of the laminate is input from the input unit 9 and given to the waveform simulator 10. Based on the layer structure information, the delay time and simulated reflected wave of all the laminated parts constituting the laminate are calculated and stored in the waveform database 8, and the display number selected by the display number selection unit 38 (see FIG. 11) displayed on the display unit 36 is obtained. Using the display number as a search key, the delay time and simulated reflected wave of the laminated part corresponding to the display number are extracted, and the simulated reflected wave is displayed at a position delayed by the delay time in a two-dimensional plane set on the display unit 36 with the horizontal axis as the time axis and the vertical axis as the amplitude axis.

[0061] The operation of gate setting by the ultrasonic imaging device 100 will be described. FIG. 10 is a flowchart showing the process S120 of the ultrasonic imaging device 100 according to the second embodiment. FIG. 11 is a diagram showing an example of the simulated reflected wave displayed on the display unit 36. The ultrasonic imaging device 100 inputs the layer structure information of the laminate to be inspected from the input unit 9 (S121). Based on the input layer structure information, waveform simulation is performed to calculate the delay time and simulated reflected wave of all the laminated parts, and they are stored in the waveform database 8 (S122).

[0062] The ultrasonic imaging device 100 obtains the display number of the laminated part to be the target laminated part from the display number selection unit 38 on the display unit 36, and displays the simulated reflected wave corresponding to the display number (S123). Then, the operator sets a gate within the display unit 36 and stores the gate information in the gate information storage unit 70 (S124), and ends the process.

[0063] FIG. 11 shows a diagram in which the third-layer simulated reflected wave is displayed on the display unit. A display number indicating which laminated part the target laminated part is, is acquired from the display number selection unit 38 displayed on the display unit 36. Using the acquired display number as a search key, the delay time and the simulated reflected wave corresponding to the display number are extracted from the waveform database 8. In FIG. 11, it is an example of input from the display number selection unit with the target laminated part being the third one. On the display unit 36, a two-dimensional plane 37 is set with the time axis on the horizontal axis and the amplitude axis on the vertical axis, and the simulated reflected wave is displayed at the position of the extracted delay time. Note that on the left side of FIG. 11, the simulated signal 39 generated by the simulated signal generation unit 5 is shown for reference.

[0064] An operator uses a pointing device connected to the ultrasonic imaging device 100 to trace a portion (range) around the simulated reflected wave displayed on the display unit 36, including the peak value of the simulated reflected wave, as the gate setting unit 34 of the laminated part corresponding to the display number, and stores the temporal position and shape thereof in the gate information storage unit 70 in association with the display number.

[0065] By executing all of these processes for all the laminated parts, gate information for all the laminated parts can be stored in the gate information storage unit.

[0066] When actually inspecting the laminate, the operator extracts the gate setting information from the gate information storage unit 70 using the gate information of the target laminated part to be inspected and the number of the target laminated part, that is, the display number as a search key, and sets the gate on the display unit 36. In this way, a highly accurate gate can be easily set for the target interface without being affected by proficiency.

[0067] In the above manner, simulated reflected waves corresponding to all the stacked portions included in the input layer structure information are calculated and stored in the waveform database 8, and gate information corresponding to all the stacked portions is calculated and stored in the gate information storage unit 70. The ultrasonic imaging device 100 calls the above-mentioned all simulated reflected waves and the corresponding gate information according to an instruction from an operator, overlaps all the simulated reflected waves in consideration of the delay time of each simulated reflected wave to constitute one simulated reflected wave, and displays it in the two-dimensional space set in the display unit 36. When displaying the overlapped simulated reflected waves in the two-dimensional space, the operator displays them according to the specification so that each simulated reflected wave can be distinguished from other simulated reflected waves. As a method of distinction, color separation may be performed, or thick lines and thin lines may be alternately displayed. This is to incorporate a method of distinction into the ultrasonic imaging device in advance. Fig. 12 shows a diagram showing the overlapped simulated reflected waves. In this example, each simulated reflected wave is distinguished by shading.

[0068] Note that the timing of displaying the overlapped simulated reflected waves may be processed by receiving an instruction from an operator, or may be automatically processed at the timing when the simulated reflected waves and the gate information corresponding to all the stacked portions are stored.

[0069] <Example screen of waveform simulator> The features of the waveform simulator 10 will be further described. Fig. 13A is a diagram showing an example of a propagation path where reflection occurs only at a specific layer. Fig. 13B is a diagram showing waveform data calculated for the propagation path where reflection occurs only at a specific layer. In the waveform simulator 10 of the present embodiment, for example, it is possible to show propagation paths of a plurality of paths where reflection occurs only at a specific layer. Considering the reflection at the interface 1 in Fig. 13A, the path 1 is the case of single reflection at the interface 1. The path 2 is the case where reflection occurs at the interface 1, reflection occurs at the interface 0, and further reflection occurs at the interface 1. The path 3 is the case where reflection occurs at the interface 1, reflection occurs at the interface 0, further reflection occurs at the interface 1, reflection occurs at the interface 0, and then reflection occurs at the interface 1. Therefore, when an operator wants to know the expected reflection waveform of only a specific layer, it can be displayed as shown in Fig. 13B.

[0070] FIG. 14 is a diagram showing an example of the screen of the waveform simulator 10. The waveform simulation screen includes a layer structure input screen, a simulation waveform display section, and the like. In the case of the comparative example (the method of Patent Document 1), only the overall waveform (thin line) of reference numeral 81 is displayed, so it was unclear from which interface the reflection occurred. On the other hand, according to the waveform simulator 10 of the present embodiment, for example, if an operator wants to know the reflected wave of interface 1, the specific interface waveform (thick line, actually a green line) of reference numeral 82 can be displayed. Therefore, for example, the operator can easily set the time gate according to the reflected wave of interface 1. Further, when displaying the simulated reflected wave, it is displayed on the two-dimensional plane in the color specified on the layer structure input screen. Therefore, the operator can easily determine from which interface the reflected wave is.

[0071] <Hardware Configuration> FIG. 15 is a diagram showing the hardware configuration of the waveform simulator 10 and the like. The computer 1200 shown in FIG. 15 is one implementation form of the input unit 9, the processing unit (the first processing unit 1, the second processing unit 2, the third processing unit 3, the fourth processing unit 4), the analog signal generation unit 5, the waveform conversion unit 6, the material database 7, and the waveform database 8 shown in FIG. 1. Each unit may be realized by a plurality of computers 1200.

[0072] The computer 1200 includes a memory 1201, a processor 1202, a storage device 1203 such as an HD (Hard Disk), a communication unit 1204 such as a NIC (Network Interface Card), a user interface unit 1205, and the like. As an example of the processor, a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit) can be considered, but other semiconductor devices may be used as long as they are the main body for executing predetermined processing.

[0073] Then, the program stored in the memory device 1203 is loaded into the memory 1201, and the loaded program is executed by the processor 1202. As a result, the functions of each processing unit, the analog signal generation unit 5, the waveform conversion unit 6, the material database 7, and the waveform database 8 shown in FIG. 1 are realized. The computer 1200 may have a display, a touch panel, a mouse, and a keyboard as the user interface unit 1205.

[0074] The waveform simulator 10 of the present embodiment described above mainly has the following features. (1) A waveform simulator that simulates a reflected wave that is reflected and returned at a target interface indicating the bottom surface of a target laminated portion indicating a desired laminated portion when ultrasonic waves are irradiated on a laminate having a plurality of layer structures, and inputs layer structure information including the material and thickness of each laminated portion constituting the laminate, and based on the layer structure information 22 and the material database 7, a first processing unit 1 that performs a first process of calculating a delay time from when ultrasonic waves are irradiated on the laminate from a probe (ultrasonic probe 50) until the probe receives the reflected wave from the target interface, a second processing unit 2 that performs a second process of calculating a first transmittance from when the ultrasonic wave is output from the probe until it reaches the target interface, a third processing unit 3 that performs a third process of calculating a reflectance of reflection generated inside the target laminated portion, and a fourth processing unit 4 that performs a fourth process of calculating a second transmittance from when the reflected wave reaches the probe from the target interface.

[0075] (2) The waveform simulator according to (1) above, which has an analog signal generation unit 5 that generates an analog signal corresponding to ultrasonic waves, calculates the delay time in all laminated portions, the first transmittance, reflectance, and second transmittance in all laminated portions, multiplies these values to calculate the amplitude change rate with respect to the analog signal, and multiplies the amplitude change rate by the analog signal to calculate an analog reflected wave, and stores it in a storage unit (waveform database 8).

[0076] According to the present embodiment, when irradiating the laminate with ultrasonic waves, it is possible to obtain a reflected wave reflected from a desired interface so that a time gate can be easily set for a test object having a plurality of layer structures with a plurality of inspection interfaces. Therefore, the operator can easily set a highly accurate gate (time gate) for the target interface without being affected by the skill level.

[0077] As described above, the waveform simulator generates a simulated reflected wave that simulates the reflected wave from the target interface when irradiating the laminate with ultrasonic waves, supports the operation of setting an appropriate gate for the reflected wave from the target interface, and enables quick operation without being affected by the skill level of the operator, the operator, thereby greatly improving the inspection efficiency of the presence or absence of defects in the laminate.

Explanation of Signs

[0078] 1 First processing unit 2 Second processing unit 3 Third processing unit 4 Fourth processing unit 5 Simulated signal generation unit 6 Waveform conversion unit 7 Material database 8 Waveform database (storage unit) 9 Input unit 10 Waveform simulator 21 Laminated structure 22 Layer structure information 30 Control device 31 Scanning control unit 32 Gate information input unit 33 Transmission / reception control unit 34 Gate setting unit 35 Image generation unit 36 Display unit 37 Two-dimensional plane 38 Display number selection unit 39 Simulated signal 40 Probe drive unit 41 Mechanism control unit 42 X-axis scanner 43 Y-axis scanner 44 Z-axis scanner 50 Ultrasonic probe (probe) 51 Encoder 52 Piezoelectric element 60 Water tank 61 Water 62 Specimen 70 Gate information storage unit 100 Ultrasonic imaging device L1 First layer L2 Second layer L3 Third layer L4 Fourth layer L5 Fifth layer S100 Process (process of waveform simulator) S120 Process (process of ultrasonic imaging device) Z Acoustic impedance Zn, Z n Acoustic impedance of the nth layer

Claims

1. A waveform simulator that simulates a reflected wave that returns after being reflected at a target interface showing the bottom surface of a target laminated portion indicating a desired laminated portion when ultrasonic waves are irradiated on a laminate having a plurality of layer structures, a first processing unit that inputs layer structure information including the material and thickness of each laminated portion constituting the laminate, and performs a first process of calculating a delay time from when the ultrasonic waves are irradiated on the laminate from a probe until the probe receives the reflected wave from the target interface based on the layer structure information and a material database; a second processing unit that performs a second process of calculating a first transmittance from when the ultrasonic waves are output from the probe until they reach the target interface; a third processing unit that performs a third process of calculating a reflectance of reflection that occurs inside the target laminated portion of the ultrasonic waves; a fourth processing unit that performs a fourth process of calculating a second transmittance from when the reflected wave reaches the probe from the target interface, and comprising a waveform simulator characterized by the above.

2. The waveform simulator according to claim 1, having a simulation signal generation unit that generates a simulation signal corresponding to the ultrasonic waves, calculating the delay time in all the laminated portions, the first transmittance, the reflectance, and the second transmittance in all the laminated portions, multiplying these values to calculate a rate of change in amplitude with respect to the simulation signal, and storing, in a storage unit, a simulated reflected wave calculated by multiplying the rate of change in amplitude by the simulation signal a waveform simulator characterized by the above.

3. The waveform simulator according to claim 2, wherein in the first process, V, which is the sound velocity of each laminated portion, is extracted from the material database using the material of each laminated portion as a search key, when D is the thickness of each laminated portion in the layer structure information, n is the number of laminations of the laminate up to the target interface, and k is a variable from 0 to n, 【Number 3】 the delay time is calculated by a waveform simulator characterized by the above.

4. The waveform simulator according to claim 2, wherein in the second process, Z, which is the acoustic impedance of each laminated portion, is extracted from the material database using the material of each laminated portion as a search key, Let n be the number of layers of the laminate up to the target interface, and Z be the acoustic impedance of the liquid medium ０ when (First transmittance) = (2(Z １ )) / (Z ０ + Z １ )) × ··· × (2Z ｎ / (Z ｎ－１ + Z ｎ )) the first transmittance is calculated by a waveform simulator characterized by the above.

5. The waveform simulator according to claim 2, In the third process, when the target laminated portion is the nth one, the acoustic impedances of the (n - 1)th, nth, and (n + 1)th laminated portions are extracted from the material database with the material of each of the laminated portions as the search key, and when the number of reflections occurring inside the target laminated portion is set to 5, (The reflectance) = ((Z ｎ＋１ ) - Z ｎ )) / ((Z ｎ＋１ ) + Z ｎ ) ３ ×((Z ｎ－１ ) – Z ｎ ) / ((Z ｎ－１ ) + Z ｎ ) ２ calculate the reflectance thereby A waveform simulator characterized by this.

6. A waveform simulator according to claim 2, In the fourth process, the acoustic impedance Z of each of the laminated portions is extracted from the material database with the material of each of the laminated portions as the search key, Let n be the number of layers of the laminate up to the target interface, and Z be the acoustic impedance of the liquid medium ０ when (Second transmittance) = (2(Z ０ )) / (Z ０ + Z １ )) × ··· × (2(Z ｎ－１ )) / (Z ｎ－1 + Z ｎ )) calculate the second transmittance thereby A waveform simulator characterized by this.

7. A ultrasonic imaging device including the waveform simulator according to any one of claims 2 to 6 and a display unit, input the layer structure information of the laminate from an input unit and give the layer structure information to the waveform simulator, calculate the delay time and the simulated reflected wave of all the laminated portions constituting the laminate based on the layer structure information, store them in a waveform database, obtain the display number selected in a display number selection unit displayed on the display unit, extract the delay time and the simulated reflected wave of the laminated portion corresponding to the display number with the display number as the search key, and display the simulated reflected wave at a position delayed by the delay time in a two-dimensional plane set on the display unit with the horizontal axis as the time axis and the vertical axis as the amplitude axis. A ultrasonic imaging device characterized by this.

8. A ultrasonic imaging device according to claim 7, The ultrasonic imaging device further includes a pointing device, sets a gate in a range traced on the display unit with the pointing device, and stores the position and shape of the gate as gate information in a gate information storage unit associated with the laminated portion corresponding to the display number. A ultrasonic imaging device characterized by this.

9. A ultrasonic imaging device according to claim 8, Store the simulated reflected waves corresponding to all the stacked portions included in the layer structure information in the waveform database, store the gate information in the gate information storage unit, call the simulated reflected waves corresponding to all the stacked portions and the delay time, superimpose the simulated reflected waves of all the stacked portions to form one simulated reflected wave, and display the reflected waves of each of the stacked portions on the two-dimensional plane while distinguishing them from the reflected waves of the other stacked portions. An ultrasonic imaging device characterized by the above.

10. The ultrasonic imaging device according to claim 7, An ultrasonic imaging device, characterized in that when displaying the simulated reflected wave, it is displayed on the display unit in a color specified on the layer structure input screen.

Images