WO2022259444A1

WO2022259444A1 - Eddy current inspection method

Info

Publication number: WO2022259444A1
Application number: PCT/JP2021/022046
Authority: WO
Inventors: 有佑岩尾
Original assignee: 東芝三菱電機産業システム株式会社
Priority date: 2021-06-10
Filing date: 2021-06-10
Publication date: 2022-12-15
Also published as: JPWO2022259444A1; CN115943304A; JP7123519B1

Abstract

The purpose of the present disclosure is to provide an inspection method capable of determining the bonding state of an electrode, which is an object to be inspected to, to a substrate without contacting the electrode. A probe (1) with a built-in coil to which an AC current is being applied is scanned along the formation direction of an electrode lead (40) which is an object to be inspected. During scanning, the probe (1) with a built-in coil is positioned above the surface of the electrode lead (40) at a predetermined distance therefrom without contacting the electrode lead (40). A plurality of detection signals corresponding to a plurality of ultrasonic joints (41) are obtained by an eddy current measuring device (3). Finally, the bonding state of the electrode lead (40) to a substrate (30) is determined based on the result of comparison between each of the plurality of detection signals and a reference level. That is, it is determined whether each of the plurality of ultrasonic joints (41) provided on the electrode lead (40) is in an unbonded state, a fractured state, or a normal state.

Description

Eddy current inspection method

The present disclosure relates to an eddy current inspection method in which an electrode provided on a substrate is applied to an inspection object using an eddy current measuring device.

As inspection methods for inspecting an electrode or the like provided on a substrate, there are, for example, the first inspection method disclosed in Patent Document 1 and the second inspection method disclosed in Patent Document 2.

The first inspection method determines the state of the electrode lead portion based on the insulation resistance value measured between the outer surface of the metal cylinder of the electrode lead portion to be inspected and the conductive lead pin of the electrode lead portion. It is an inspection method that

In the first inspection method, inspection is possible even in a narrow space, and it is a relatively inexpensive soldering inspection method using an inspection device.

The second inspection method uses the leads of the lead frame bonded to the substrate as the inspection object. The second inspection method includes the following first to fourth steps.

　First step... Set it in the pressurizing device, pressurize the lead of the lead frame from above, and turn on the annular lighting device.

　Second step... An imaging device captures an image including the lead joint, and the image data obtained by this imaging is converted into a digital image signal by an A/D converter.

Third step: The image data corresponding to the lead joint portion is extracted by the processing device as a binarized image so as to leave a portion brighter than a certain value.

　Fourth step... Determine the lead status based on the binarized image.

By the second inspection method described above, it is possible to accurately distinguish between unbonded leads and bonded leads.

JP 2016-151484 A JP-A-10-185527

However, although the first inspection method described above performs the inspection itself non-destructively, there is a problem that the inspection cannot be performed unless the object to be inspected is in contact with the object.

In addition, in the first inspection method, when the inspection object includes a fractured portion, there is also a problem that the presence of the fractured portion cannot be detected if the contact portion is a normal portion instead of the fractured portion. .

In addition, the second inspection method described above pressurizes the lead, which is the object to be inspected, during the execution of the first step, so there is a problem that the object to be inspected cannot be inspected without contact.

In addition, in the second inspection method, although it is possible in principle to detect the non-bonded state at the end of the lead, it is extremely difficult to determine the bonded state in the intermediate region of the lead. . Furthermore, the second inspection method also has the problem that it is not possible to accurately determine the broken portion of the lead.

The present disclosure solves the problems of the conventional inspection methods including the first and second inspection methods described above, and determines the bonding state of the electrode to the substrate without contacting the electrode to be inspected. The purpose is to provide an inspection method that can

An eddy current inspection method of the present disclosure is an eddy current inspection method using an eddy current measurement device that generates an eddy current in an inspection object and obtains a detection signal indicating the state of the eddy current, wherein the eddy current measurement device is A probe having a built-in coil and an electrode provided on a substrate serves as the test object, and (a) a step of applying an alternating current to the coil in the probe to bring it into an alternating current applied state, and (b) and scanning the probe with the alternating current applied along the direction of formation of the electrode, wherein during the execution period of step (b), the probe is not in contact with the electrode, and the surface of the electrode is scanned. is positioned above at a predetermined distance from, eddy current is generated on the surface of the electrode when step (b) is executed, the detection signal is obtained from the eddy current measuring device every moment, and (c) is obtained every moment determining the state of bonding of the electrode to the substrate based on a comparison result between the detection signal obtained and a reference level.

In the eddy current inspection method of the present disclosure, in step (b), detection signals are acquired by scanning the probe along the electrode formation direction without contacting the electrodes.

Therefore, the eddy current inspection method of the present disclosure can determine the bonding state of the electrode to the substrate when step (c) is performed without touching the electrode, which is the inspection object.

The objects, features, aspects and advantages of the present disclosure will become more apparent with the following detailed description and accompanying drawings.

1 is an explanatory diagram schematically showing an eddy current inspection method according to an embodiment of the present disclosure; FIG. 2 is a flow chart showing a processing procedure of the eddy current inspection method of the embodiment shown in FIG. 1; FIG. 4 is an explanatory diagram showing an output waveform displayed on the display of the detected voltage display PC; FIG. 3 is a flow chart showing a processing procedure of selection processing of a calibration reference portion shown in FIG. 2; FIG. FIG. 4 is an explanatory diagram schematically showing inspection contents of an eddy current preliminary inspection; It is explanatory drawing which shows typically the test|inspection method by a basic technique.

<Basic technology>
FIG. 6 is an explanatory diagram schematically showing an inspection method based on the basic technique. FIG. 6 shows an XYZ orthogonal coordinate system.

As shown in the figure, an electrode lead 40 is provided on a substrate 30, and the electrode lead 40 has a plurality of ultrasonic joints 41. As shown in FIG. Each of the plurality of ultrasonic bonding portions 41 is a metal foil portion that becomes a bonding region with the surface of the substrate 30 using an ultrasonic bonding method. That is, the electrode lead 40 and the surface of the substrate 30 are joined by a plurality of ultrasonic joints 41 .

The inspection method of the basic technology is to use the 90-degree strength tensile tester 60 to contact the electrode lead 40 and inspect the joint state of each of the plurality of ultrasonic joints 41 with the substrate 30 .

The 90-degree strength tension measuring instrument 60 has a clip 62 connected via a connection cable 64, and the clip 62 can grip the tip portion 40t of the electrode lead 40.

In the inspection method of the basic technique, the tip portion 40t of the electrode lead 40 is held by the clip 62, and the strength tension measuring instrument 60 is lifted by 90 degrees along the tensile direction F6 to force the electrode lead 40 from the substrate 30. It is done by pulling it off.

Since the substrate 30 and electrode leads 40 are arranged on the XY plane shown in FIG.

For example, in FIG. 6, the bonding strength measured by the 90-degree strength tension measuring device 60 is the measured bonding strength when the ultrasonic bonding portion 41 existing on the leftmost side (−X direction side) in the drawing is peeled off.

In the basic technology, if the measured joint strength is equal to or higher than the reference strength, it can be determined as the normal joint 41A, and if it is less than the reference strength, it can be judged as the unjoined section 41C. It should be noted that whether or not the ultrasonic bonding portion 41 is the fracture portion 41B can be recognized by visually confirming the presence or absence of the gap 44 .

For example, as shown in FIG. 6, of the four ultrasonically bonded portions 41, from the left in the drawing, a normal bonded portion 41A, a broken portion 41B, an unbonded portion 41C, and a normal bonded portion 41A are assumed. In this case, the measured bonding strength of each of the first and fourth ultrasonic bonding portions 41 from the left is greater than or equal to the reference strength.

On the other hand, the measured bonding strength of the third ultrasonic bonding portion 41 from the left is below the reference strength. Since there is a floating space 48 between the unbonded portion 41C and the surface of the substrate 30, the unbonded portion 41C cannot be visually confirmed from above the electrode lead 40. FIG. The inspection method of the basic technique can accurately determine the unbonded portion 41C.

As described above, the inspection method of the basic technique uses the 90-degree strength tensile tester 60 to peel off the electrode lead 40 from the substrate 30, thereby checking the bonding state of each of the plurality of ultrasonic bonding portions 41 to the substrate 30. inspecting.

However, in the inspection method of the basic technology, the combination structure of the substrate 30 and the electrode lead 40 is destroyed by contacting the electrode lead 40 and then peeling off the electrode lead 40 from the substrate 30 . Therefore, the board 30 used in the inspection cannot be used.

That is, like the first and second inspection methods described as the prior art, the inspection method of the basic technology has the problem that it is not possible to determine the bonding state of the electrode to the substrate without contacting the electrode. is doing. The inspection method of the embodiment described below aims to solve the above-described problems.

<Embodiment>
FIG. 1 is an explanatory diagram schematically showing an eddy current inspection method according to an embodiment of the present disclosure. An XYZ orthogonal coordinate system is shown in FIG. The eddy current measuring device 10, except for the probe 1 with a built-in coil, is out of the scope of the XYZ orthogonal coordinate system. The oscilloscope 7, the connection cable 8, and the detected voltage display PC 9 are also excluded from the XYZ orthogonal coordinate system.

As shown in the figure, an electrode lead 40 is provided on a substrate 30, and the electrode lead 40 is an object to be inspected. The electrode lead 40 has a plurality of ultrasonic bonding portions 41, and is bonded to the surface of the substrate 30 at the plurality of ultrasonic bonding portions 41 by ultrasonic bonding processing.

The electrode lead 40 corresponds to the "electrode" provided on the substrate 30, and the plurality of ultrasonic joints 41 correspond to the "plurality of joints" provided on the electrode lead 40 separately from each other.

A plurality of ultrasonic bonding portions 41 are a plurality of metal foil portions allocated as bonding regions with the surface of the substrate 30 . That is, the plurality of ultrasonic bonding portions 41 are bonding regions with the surface of the substrate 30 using the ultrasonic bonding method.

The electrode lead 40 has a film thickness of about 1.1 mm and is formed on the surface of the substrate 30 extending in the X direction. Each ultrasonic bonding portion 41 has the same size, has an area including at least a 1 mm×1 mm square, and has a thickness of, for example, about 1.1 mm.

The eddy current inspection method of the present embodiment uses the eddy current measuring device 10 to inspect the bonding state of each of the plurality of ultrasonic bonding portions 41 to the surface of the substrate 30 without contacting the electrode lead 40. is.

The eddy current measuring device 10 includes a coil-embedded probe 1, a connection cable 2, an eddy current measuring instrument 3, a connection probe 5, and a probe holder 11 as main components. The eddy current measuring device 10 is a device that obtains a detection signal indicating the state of eddy currents generated on the surface of the electrode lead 40 .

The coil built-in probe 1 is a probe that has a built-in coil inside. By passing an alternating current of a predetermined frequency through the built-in coil in the coil built-in probe 1, the coil built-in probe 1 is put into an alternating current applied state, and a magnetic field is generated in the built-in coil. Note that the eddy current measuring device 3 has the function of applying an alternating current.

The probe folder 11 holds the coil-incorporating probe 1 with the tip portion of the coil-incorporating probe 1 exposed.

The coil-incorporated probe 1 is connected to an eddy current measuring instrument 3 via a connection cable 2, and the eddy current measuring instrument 3 executes a predetermined operation based on the eddy current detection result detected by the coil-incorporated probe 1. A detection signal is obtained. The detection signal is a signal that has a positive correlation with the eddy current detection result.

As an eddy current detection result, for example, the impedance of the built-in coil in the probe with a built-in coil 1 can be considered, and the change in the state of the eddy current can be recognized from the change in the impedance of the built-in coil. Therefore, the detection signal obtained from the eddy current measuring device 3 is a signal indicating the state of the eddy current generated on the surface of the electrode lead 40 . The state of eddy currents includes the magnitude and distribution of eddy currents.

A detected voltage display PC (Personal Computer) 9 is provided as an external device connected to the eddy current measurement device 10, and the detected voltage display PC 9 is connected to the eddy current measurement device 10 via an oscilloscope 7 and a connection cable 8. It is connected to the probe 5 for use.

A detection signal obtained by the eddy current measuring instrument 3 is applied to the oscilloscope 7 via the connection probe 5 . The oscilloscope 7 converts the received detection signal into a display detection signal that can be displayed on the display of the detected voltage display PC 9 . This display detection signal is output to the detected voltage display PC 9 via the connection cable 8 .

The detection voltage display PC 9 displays the output waveform LV of the detection signal on the display based on the detection signal for display.

The eddy current inspection method of the present embodiment is executed using the eddy current measuring device 10 having such a configuration. The eddy current inspection method of the present embodiment is an inspection method for determining the bonding state of the plurality of ultrasonic bonding portions 41 provided on the electrode lead 40 to the surface of the substrate 30 .

FIG. 2 is a flow chart showing the processing procedure of the eddy current inspection method of this embodiment shown in FIG. Hereinafter, the processing contents of the eddy current inspection method of the present embodiment will be described with reference to FIG.

First, in step S1, an alternating current is applied to the built-in coil in the probe with a built-in coil 1 to bring it into an alternating current applied state.

After step S1, in step S2, one joint is selected from a plurality of ultrasonic joints 41, which are a plurality of joints, as a calibration reference portion (reference joint). Details of the selection of the calibration reference part will be described later.

For convenience of explanation, it is assumed that the leftmost ultrasonic joint 41 of the four ultrasonic joints 41 shown in FIG. 1 is selected as the calibration reference part 41S (reference joint).

After step S2, in step S3, initial setting of the calibration reference unit 41S is performed. That is, the tip of the probe with a built-in coil 1 is arranged above the surface of the calibration standard portion 41S with a predetermined distance therebetween, and an eddy current is generated on the surface of the calibration standard portion 41S.

Then, based on the eddy current detection result obtained by the probe 1 with a built-in coil, the eddy current measuring instrument 3 obtains a detection signal for calibration reference. Therefore, the calibration process is executed by pressing the calibration button provided on the eddy current measuring instrument 3, etc., and the signal value of the calibration reference detection signal is initialized to the initial set value ("0"). do. Thus, the signal value "0" indicated by the calibration reference detection signal corresponding to the calibration reference section 41S becomes the reference level. That is, the reference level is the signal value of the detection signal when the probe with built-in coil 1 is arranged above the calibration reference section 41S.

After execution of step S3, when the signal value of the detection signal obtained from the eddy current measuring device 3 is positive, the signal value is higher than the reference level, and when the signal value of the detection signal is negative, the signal value is lower than the reference level. Become.

After that, in step S4, an eddy current inspection is performed on the electrode lead 40. That is, scanning SC1 is performed for scanning the coil-embedded probe 1 in the alternating current applied state along the direction of formation of the electrode lead 40 (X direction). The start position of scan SC1 is above the tip of the left end of electrode lead 40, and the scanning speed of scan SC1 along the X direction is set to, for example, 1 m/s.

During the execution period of step S<b>4 , the probe 1 with a built-in coil is positioned above the surface of the electrode lead 40 at a predetermined distance without contacting the electrode lead 40 . The predetermined distance is set to approximately 1 mm.

Therefore, an eddy current is generated on the surface of the electrode lead 40 when step S4 is executed, and the probe 1 with a built-in coil can obtain eddy current detection results moment by moment. Furthermore, by the arithmetic processing of the eddy current measuring device 3, a detection signal based on the eddy current detection result is obtained moment by moment. As described above, the detection signal indicates the state of eddy currents generated on the surface of the electrode lead 40 .

The time period during which the tip of the probe with a built-in coil 1 passes above each of the ultrasonic joints 41 during the execution of the scan SC1 is determined by the position and size of each ultrasonic joint 41 and the scanning speed of the probe with a built-in coil 1. can be derived.

Therefore, a plurality of detection signals corresponding to a plurality of ultrasonic joints 41 can be obtained by executing step S4.

Finally, in step S5, ultrasonic bonding state determination processing is executed. That is, in step S5, the connection state of the electrode lead 40 to the substrate 30 is determined based on the result of comparison between the detection signal obtained every moment and the reference level.

In this embodiment, in step S5, based on the result of comparison between each of the plurality of detection signals corresponding to the plurality of ultrasonic bonding portions 41 and the reference level, bonding on the surface of the substrate 30 of each of the plurality of ultrasonic bonding portions 41 is performed. judging the state.

The determination process executed in step S5 is a process of determining to which of the normal bonded portion 41A, broken portion 41B, and unbonded portion 41C each of the plurality of ultrasonically bonded portions 41 corresponds. The determination process executed in step S5 includes the following first to third determinations.

First judgment: If there is a first type detection signal having a significant difference from the reference level (“0”) in the positive direction among the plurality of detection signals corresponding to the plurality of ultrasonic bonding portions 41, the plurality of Of the ultrasonic joints 41, the ultrasonic joints 41 corresponding to the first type detection signal are determined to be in an unbonded state. As a result, the unbonded ultrasonically bonded portion 41 is classified as an unbonded portion 41C.

Second judgment: If there is a second type detection signal having a significant difference from the reference level in the negative direction among the plurality of detection signals described above, the second type detection is performed among the plurality of ultrasonic joints 41. The ultrasonic joint 41 corresponding to the signal is determined to be broken. As a result, the ultrasonically bonded portion 41 in the fractured state is classified as the fractured portion 41B.

Third determination: If there is a third-class detection signal that does not correspond to any of the above-described first-class and second-class detection signals among the plurality of detection signals described above, The ultrasonic joint 41 corresponding to the third type detection signal is determined to be in a normal state. As a result, the ultrasonic joints 41 in the normal state are classified as normal joints 41A.

The reason why the signals can be classified into the first to third detection signals according to the first to third determinations will be described below.

As shown in FIG. 1, a gap 44 exists in at least a portion of the breaking portion 41B. Air gaps 44 often extend through electrode leads 40 . Therefore, the fractured portion 41B has a first distance characteristic that there is a portion with a longer distance from the coil in the coil-embedded probe 1 compared to the normal bonded portion 41A due to the presence of the air gap 44 .

As shown in FIG. 1 , a floating space 48 exists between the unbonded portion 41C and the surface of the substrate 30 . Therefore, the fractured portion 41B has a second distance characteristic that there is a region where the distance from the coil in the coil-embedded probe 1 is shorter than that of the normal joint portion 41A due to the presence of the floating space 48. there is

The closer the distance from the ultrasonic joint 41 to the built-in coil in the probe with a built-in coil 1 is, the larger the eddy current detection result obtained by the probe with a built-in coil 1 becomes. Therefore, when the eddy current measuring device 3 obtains a detection signal having a positive correlation with the eddy current detection result, the signal value of the detection signal increases in the order of the broken portion 41B, the normal bonded portion 41A, and the unbonded portion 41C. is assumed to have

Therefore, the above-described first to third determinations can be made based on the above-described first and second distance characteristics between the normal bonded portion 41A, the broken portion 41B, and the unbonded portion 41C.

Depending on the arithmetic expression used by the eddy current measuring instrument 3, a detection signal having a negative correlation with the eddy current detection result may be obtained.

In this case, it is presumed that the signal value of the detection signal decreases in the order of the broken portion 41B, the normal bonded portion 41A, and the unbonded portion 41C. It is possible to make judgments equivalent to the first to third judgments.

That is, the above-described first to third determinations can be expanded as follows by using the plurality of ultrasonic joints 41 as a plurality of joints.

First judgment: If there is a type 1 detection signal that has a significant difference from the reference level in one of the positive direction and the negative direction among the plurality of detection signals, the type 1 detection signal among the plurality of joints The joint corresponding to the detection signal is determined as the unjoined unjoined portion 41C.

Second judgment: If there is a type 2 detection signal having a significant difference from the reference level in the other of the positive direction and the negative direction among the plurality of detection signals, the type 2 detection signal among the plurality of joints The joint corresponding to the detection signal is determined to be the broken portion 41B in the broken state.

Third judgment: If there is a third-class detection signal that does not correspond to either the first or second-class detection signals among the plurality of detection signals, it corresponds to the third-class detection signal among the plurality of joints. The joint portion is determined to be the normal joint portion 41A in the normal joint state.

FIG. 3 is an explanatory diagram showing the output waveform LV displayed on the display of the detected voltage display PC 9. FIG. An output waveform LV indicates the inspection result for the electrode lead 40 shown in FIG.

　In order to obtain the output waveform LV shown in FIG. In the first alternating current, the frequency is set to 600 kHz and the phase is set to 65.0 deg. In the second AC current, the frequency is set to 600 kHz and the phase is set to 225.0 deg.

Then, by applying the first alternating current to the built-in coil in the coil built-in probe 1, the first eddy current detection result is obtained in the coil built-in probe 1, and the second alternating current is applied to the built-in coil. As a result, the second eddy current detection result is obtained in the probe 1 with a built-in coil.

The eddy current measuring instrument 3 obtains a detection signal by performing a predetermined calculation based on the first and second eddy current detection results.

A detection signal obtained by the eddy current measuring instrument 3 is applied to the oscilloscope 7 via the connection probe 5 . The oscilloscope 7 converts the received detection signal into a display detection signal that can be displayed on the detected voltage display PC 9 . This display detection signal is output to the detected voltage display PC 9 via the connection cable 8, and the output waveform LV shown in FIG. 3 is displayed on the display of the detected voltage display PC 9. FIG.

As shown in FIG. 1, the electrode lead 40 has four ultrasonic joints 41, and the leftmost ultrasonic joint 41 is selected as the calibration reference part 41S.

As described above, the time period during which the tip of the probe with a built-in coil 1 passes above each of the four ultrasonic joints 41 is derived from the position and size of each ultrasonic joint 41 and the scanning speed of the probe with a built-in coil 1. be able to. Hereinafter, for convenience of explanation, the four ultrasonic joints 41 will be referred to as first, second, third and fourth joints from the left.

As shown in FIG. 3, the output waveforms LV in the time periods T1 to T4 are the first to fourth detection signals corresponding to the first to fourth junctions. Here, the positive direction threshold indicating a significant difference in the positive direction is assumed to be "+0.3V", and the negative direction threshold indicating a significant difference in the negative direction is assumed to be "-0.2V".

　Since the first joint is the calibration reference part 41S, the signal value of the output waveform LV in the time period T1 indicates 0V. Therefore, since the first detection signal is a type 3 detection signal that does not correspond to any of the type 1 and type 2 detection signals described above, the first joint is determined to be the normal joint 41A in a normal state. be.

The minimum signal value of the output waveform LV in time period T2 is below -0.2V. Therefore, since the second detection signal is the second type detection signal described above, the second joint portion is determined to be the broken portion 41B in the broken state.

The maximum signal value of the output waveform LV in time zone T3 exceeds +0.3V. Therefore, since the third detection signal is the type 1 detection signal described above, the third joint is determined to be the unjoined unjoined portion 41C.

The signal value of the output waveform LV in time period T4 is around 1V, but the minimum signal value exceeds -0.2V and the maximum signal value is below +0.3V. Therefore, since the fourth detection signal is a type 3 detection signal that does not correspond to any of the type 1 and type 2 detection signals, the fourth joint is determined to be the normal joint 41A in the normal state. be.

In the eddy current inspection method of the present embodiment, in step S4, by scanning the probe 1 with built-in coil along the formation direction of the electrode lead 40 without contacting the electrode lead 40, the eddy current measuring device 3 A detection signal is acquired.

Therefore, in the eddy current inspection method of the present embodiment, it is possible to determine the bonding state of the electrode lead 40 to the surface of the substrate 30 during execution of step S5 without touching the electrode lead 40, which is the object to be inspected. .

In the eddy current inspection method of the present embodiment, by performing the first to third determinations when step S5 is executed, for each of the plurality of ultrasonic joints 41, Which state it is can be determined without touching the electrode lead 40 .

FIG. 4 is a flow chart showing the processing procedure of the selection process of the calibration reference unit 41S shown in step S2 of FIG. Hereinafter, selection contents of the calibration reference unit 41S in step S2 will be described with reference to FIG.

First, in step S21, a spare substrate is prepared. A non-bonded preliminary electrode is arranged on the surface of the preliminary substrate.

The spare substrate and spare electrode are members prepared separately from the substrate 30 and the electrode lead 40 , the spare substrate is the substrate corresponding to the substrate 30 , and the spare electrode is the electrode corresponding to the electrode lead 40 . Therefore, it is desirable that the preliminary substrate be made of the same material and the same size as the substrate 30 , and that the preliminary electrode be made of the same material and the same size as the electrode lead 40 .

Next, in step S22, a pressing process is performed on the spare electrode. That is, at least the preliminary reference area of the preliminary electrode is pressed from above using a roller or the like. Note that the preliminary reference area is a partial area of the preliminary electrode, and is preferably set to the same extent as the ultrasonic bonding portion 41 .

As a result, the preliminary reference area of the preliminary electrode is conditioned, and the preliminary reference area is brought into close contact with the surface of the preliminary substrate. In order to increase the degree of adhesion of the preliminary reference area to the surface of the preliminary substrate, it is desirable to perform the pressing process on the entire area of the preliminary electrode.

Then, in step S23, a preliminary reference signal is obtained. That is, the coil-incorporating probe 1 is arranged so that the tip of the coil-incorporating probe 1 is located above the surface of the preliminary reference region at a predetermined distance without contacting the preliminary electrode. The predetermined distance is set to approximately 1 mm.

Therefore, when step S23 is executed, an eddy current is generated on the surface of the preliminary reference area in the preliminary electrode, and the coil-embedded probe 1 acquires the eddy current detection result. Then, a preliminary reference signal based on the eddy current detection result is obtained by arithmetic processing of the eddy current measuring device 3 .

It is presumed that the signal value of this preliminary reference signal is the same as or approximate to the signal value of the detection signal of the normal joint 41A. This is because the preliminary reference area is kept in close contact with the surface of the preliminary substrate by step S22.

After executing step S23, in step S24, the calibration button provided on the eddy current measuring instrument 3 is pressed to perform calibration processing so that the signal value of the preliminary reference signal becomes "0".

After the calibration process described above, the detection signal obtained from the eddy current measuring instrument 3 has the following properties. A positive signal value of the detection signal implies a signal value higher than that of the preliminary reference signal, and a negative signal value of the detection signal implies a signal value lower than that of the preliminary reference signal.

Next, in step S25, an eddy current preliminary inspection is performed to acquire a plurality of preliminary detection signals using the electrode leads 40 on the substrate 30 as inspection objects.

Fig. 5 is an explanatory diagram schematically showing the inspection contents of the eddy current preliminary inspection. FIG. 5 shows an XYZ orthogonal coordinate system. Note that the eddy current measuring device 10 is outside the scope of the XYZ orthogonal coordinate system. It should be noted that illustration of the substrate 30 is omitted in FIG.

As shown in the figure, a plurality of ultrasonic waves are applied to each of the plurality of ultrasonic bonding portions 41 of the electrode lead 40 to be inspected along the Y direction perpendicular to the formation direction (X direction) of the electrode lead 40. It scans across above each joint 41 . In the example shown in FIG. 5, three ultrasonic joints 41 are shown, so three scans SC11 to SC13 are performed on the three ultrasonic joints 41. FIG.

As described above, in step S25, the scans SC11 to SC13 are sequentially performed, so that the coil-embedded probe 1 in the alternating current applied state is sequentially arranged above each of the plurality of ultrasonic joints 41. FIG. During scans SC11 to SC13, the lower tip of the probe with a built-in coil 1 is positioned so that it is at a height of about 1 mm from the plurality of ultrasonic joints 41 . Therefore, eddy currents are generated on the surface of each of the plurality of ultrasonic joints 41 during the execution of scans SC11 to SC13.

After that, the coil-embedded probe 1 obtains the eddy current detection results for each of the scans SC11 to SC13. Here, for convenience of explanation, the eddy current detection results obtained by the scans SC11 to SC13 are referred to as first to third eddy current detection results.

Furthermore, by the arithmetic processing of the eddy current measuring device 3, first to third preliminary detection signals based on the first to third eddy current detection results are obtained. The first to third preliminary detection signals become a plurality of preliminary detection signals.

Finally, in step S26, the calibration reference portion 41S is determined from the plurality of ultrasonic bonding portions 41. That is, among the signal values of the plurality of preliminary detection signals obtained in step S25, the preliminary detection signal having the signal value closest to "0" calibrated in step S24 is determined as the determined preliminary detection signal.

After that, among the plurality of ultrasonic joints 41, the ultrasonic joint 41 corresponding to the preliminary detection signal for determination is determined as the calibration reference part 41S. This calibration reference portion 41S serves as a reference joint portion. By executing step S2 including steps S21 to S26 in this manner, one calibration reference portion 41S can be selected from the plurality of ultrasonic bonding portions 41. FIG.

In the example shown in FIG. 5, among the first to third preliminary detection signals obtained by scanning SC11 to SC13, the signal value closest to "0" is selected as the selected preliminary detection signal.

In the eddy current inspection method of the present embodiment, by executing step S2 including steps S21 to S26, there is no contact with the electrode lead 40, which is the object to be inspected, from the plurality of ultrasonic joints 41 to the reference joint. can be selected.

As a result, the eddy current inspection method of the present embodiment can accurately obtain the reference level by selecting the highly reliable calibration reference portion 41S. It is possible to accurately determine the state of bonding to the surface of the.

The electrode lead 40 is bonded to the surface of the substrate 30 at a plurality of ultrasonic bonding portions 41 by ultrasonic bonding processing. That is, each of the plurality of ultrasonic bonding portions 41 becomes a bonding region with the surface of the substrate 30 .

Regarding the eddy current inspection method of the present embodiment, if the thickness of each of the plurality of ultrasonic joints 41 is 0.01 mm or more, the bonding state of each of the plurality of ultrasonic joints 41 to the substrate 30 can be accurately determined. It has been confirmed that it can be done.

Therefore, according to the eddy current inspection method of the present embodiment, for example, even for a plurality of ultrasonic bonding portions 41 each having a relatively thin film thickness of about 0.11 mm, bonding to the surface of the substrate 30 status can be determined.

Regarding the eddy current inspection method of the present embodiment, if each of the plurality of ultrasonic joints 41 has a planar shape including a square with a side length of 1 mm in plan view, the plurality of ultrasonic joints It has been confirmed that the state of bonding of each of the substrates 41 to the substrate 30 can be accurately determined.

Therefore, according to the eddy current inspection method of the present embodiment, for example, even for a plurality of ultrasonic bonding portions 41 each having a planar shape of about a square with a side length of 1 mm, the state of bonding to the substrate 30 can be determined.

In the eddy current inspection method of the present embodiment, the scanning speed of the coil built-in probe 1 during the eddy current inspection performed in step S4 is set to 1 m/s or more.

Therefore, according to the eddy current inspection method of the present embodiment, since the scanning speed of the probe with built-in coil 1 executed in step S4 is 1 m/s or more, the execution time of step S4 can be kept relatively short. Inspection time can be shortened.

That is, the inspection time of the eddy current inspection method of the present embodiment does not become long even for the electrode lead 40 having a relatively long formed length.

Furthermore, in the eddy current inspection method of the present embodiment, the first and second alternating currents having the same frequency and different phases are used as the alternating currents applied in step S1. can obtain a high detection signal.

As a result, the eddy current inspection method of the present embodiment has the effect of being able to accurately determine the bonding state of the electrode lead 40 to the surface of the substrate 30 .

<Others>
In the above-described embodiment, the first and second alternating currents having the same frequency and different phases are used as the alternating currents applied to the probe with a built-in coil 1. However, the first and second alternating currents have different frequencies. and phase, if at least one is different, a similar effect can be expected.

Furthermore, the eddy current measuring instrument 3 may independently obtain a first detection signal based on the first eddy current detection result and a second detection signal based on the second eddy current detection result. good. The first detection signal corresponds to the first alternating current, and the second detection signal corresponds to the second alternating current.

In this case, two output waveforms LV are obtained, so it is desirable to use two independent probes 5a and 5b as the connection probes 5, as shown in FIG.

Also, even if a single alternating current is used as the alternating current applied in step S1, the effect of being able to determine the bonding state of the electrode lead 40 to the surface of the substrate 30 can be expected. This is because the eddy current measuring device 3 can generally obtain a detection signal based on the eddy current detection result even when using a single alternating current.

That is, even if a single alternating current is used as the alternating current applied in step S1, the above-mentioned Similar determinations to the first to third determinations described above are possible.

Further, instead of the process shown in FIG. 4 as the selection process of the calibration reference part 41S in step S2 shown in FIG. A manual selection process may be used to select the ultrasonically bonded portion 41 in a stable bonded state as the calibration reference portion 41S.

However, when using manual selection processing, it is necessary to contact the electrode lead 40 . Furthermore, since the manual selection process described above is a manual and subjective process, the accuracy of selection of the calibration reference unit 41S cannot be said to be high. Therefore, it is desirable to execute the process shown in FIG. 4 as the selection process for the calibration reference unit 41S shown in FIG.

Although the present disclosure has been described in detail, the above description is illustrative in all aspects, and the present disclosure is not limited thereto. It is understood that numerous variations not illustrated can be envisioned without departing from the scope of the present disclosure.

1 probe with built-in coil 3 eddy current measuring device 9 PC for displaying detected voltage
REFERENCE SIGNS LIST 10 Eddy current measuring device 30 Substrate 40 Electrode lead 41 Ultrasonic joint 41A Normal joint 41B Broken portion 41C Unjoined portion 41S Calibration reference portion

Claims

An eddy current inspection method using an eddy current measuring device for generating an eddy current in an object to be inspected and obtaining a detection signal indicating the state of the eddy current, the eddy current measuring device having a probe with a built-in coil, The electrode provided on the substrate is the object to be inspected,
(a) applying an alternating current to a coil in the probe to bring it into an alternating current applied state;
(b) scanning the probe with the alternating current applied along the direction in which the electrodes are formed; is positioned above the surface of the electrode at a predetermined distance, eddy currents are generated on the surface of the electrode when step (b) is executed, and the detection signal is obtained from the eddy current measuring device every moment,
(c) further comprising a step of judging the bonding state of the electrode to the substrate based on the result of comparison between the detection signal and the reference level obtained from time to time;
An eddy current inspection method comprising:
The eddy current inspection method according to claim 1,
wherein the electrode has a plurality of joints spaced apart from each other, the plurality of joints being allocated as a joint area with the surface of the substrate;
The eddy current inspection method includes:
(d) performing after step (a) and before step (b), further comprising selecting a joint from the plurality of joints as a reference joint;
the reference level is a signal value of the detection signal when the probe is placed above the reference junction;
obtaining a plurality of detection signals corresponding to the plurality of junctions when performing step (b);
The step (c) includes
(c-1) when there is a type 1 detection signal having a significant difference from the reference level in one of the positive direction and the negative direction among the plurality of detection signals, determining that the joint corresponding to the type 1 detection signal is in an unjoined state;
(c-2) If, among the plurality of detection signals, there is a type 2 detection signal having a significant difference from the reference level in the other of the positive direction and the negative direction, Determining that the joint corresponding to the second type detection signal is in a broken state,
(c-3) When there is a third-class detection signal that does not correspond to any of the first and second-class detection signals among the plurality of detection signals, the third-class detection is performed among the plurality of joints. determining that the junction corresponding to the signal is in a normal state;
Eddy current inspection method.
The eddy current inspection method according to claim 2,
The step (d) includes
(d-1) preparing a preliminary substrate having an unbonded preliminary electrode disposed thereon;
(d-2) pressing the preliminary reference area of the preliminary electrode from above to bring the preliminary reference area into close contact with the surface of the preliminary substrate;
(d-3) placing the probe to which the alternating current is applied above the preliminary reference region of the preliminary electrode, wherein the surface of the preliminary reference region is swirled when step (d-3) is performed; a current is generated and a preliminary reference signal is obtained from the eddy current measuring device;
(d-4) further comprising the step of sequentially arranging the probes to which the alternating current is applied above the plurality of joints, wherein eddy currents are generated on the surfaces of the plurality of joints when step (d-4) is performed; is generated, a plurality of preliminary detection signals corresponding to the plurality of joints are obtained from the eddy current measuring device,
(d-5) determining, among the plurality of preliminary detection signals, a signal having a signal value closest to the preliminary reference signal as a determined preliminary detection signal, and corresponding to the determined preliminary detection signal among the plurality of junctions; further comprising determining a junction as the reference junction;
Eddy current inspection method.
The eddy current inspection method according to claim 2 or 3,
The plurality of bonding portions are bonding regions with the surface of the substrate using an ultrasonic bonding method,
The thickness of each of the plurality of joints is 0.01 mm or more,
Eddy current inspection method.
The eddy current inspection method according to any one of claims 2 to 4,
Each of the plurality of joints has a planar shape including a square with a side length of 1 mm in plan view,
Eddy current inspection method.
The eddy current inspection method according to any one of claims 1 to 5,
The scanning speed of the probe performed in step (b) is 1 m/s or more,
Eddy current inspection method.
The eddy current inspection method according to any one of claims 1 to 6,
The alternating current includes a first alternating current and a second alternating current, wherein the first and second alternating currents differ in at least one of frequency and phase.
Eddy current inspection method.