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CN-115943304-B - Eddy current inspection method

CN115943304BCN 115943304 BCN115943304 BCN 115943304BCN-115943304-B

Abstract

The purpose of the present application is to provide an inspection method capable of judging the bonding state of an electrode to a substrate without contacting the electrode as an inspection object. A detector (1) built in a coil in an alternating current application state is scanned along the formation direction of an electrode lead (40) as an inspection object. A detector (1) with built-in coil during scanning is positioned above the surface of an electrode lead (40) at a predetermined distance without contacting the electrode lead (40). Then, a plurality of detection signals corresponding to the plurality of ultrasonic joints (41) are obtained by an eddy current measuring device (3). Finally, a bonding state of the electrode lead (40) to the substrate (30) is determined based on a result of comparing each of the plurality of detection signals with the reference level. That is, it is determined which of the non-joined state, the broken state and the normal state is in for each of the plurality of ultrasonic joining portions (41) provided on the electrode lead (40).

Inventors

  • IWAO YUSUKE

Assignees

  • 东芝三菱电机产业系统株式会社

Dates

Publication Date
20260508
Application Date
20210610

Claims (6)

  1. 1. An eddy current inspection method for generating an eddy current in an object to be inspected and obtaining a detection signal indicating a state of the eddy current, using an eddy current measuring apparatus having a probe with a built-in coil, an electrode provided on a substrate being the object to be inspected, the eddy current inspection method comprising: (a) A step of applying an alternating current to a coil in the detector to bring the coil into an alternating current application state, and (B) A step of scanning the probe in the alternating current application state along the electrode formation direction, wherein the probe is not in contact with the electrode but is positioned above the surface of the electrode at a predetermined distance during the execution of the step (b), an eddy current is generated on the surface of the electrode during the execution of the step (b), the detection signal is obtained by the eddy current measuring device without interruption, The eddy current inspection method may further comprise, (C) A step of determining a bonding state of the electrode to the substrate based on a result of comparing the detection signal obtained without interruption with a reference level, The electrode has a plurality of bonding portions which are discrete from each other, the plurality of bonding portions are allocated as bonding regions with the surface of the substrate, The eddy current inspection method further includes: (d) A step of selecting one joint from the plurality of joints as a reference joint, which is performed after the step (a) and before the step (b), The reference level is a signal value of the detection signal when the detector is arranged above the reference joint portion, Obtaining a plurality of detection signals corresponding to the plurality of joints at the time of execution of the step (b), In the step (c) of the above-mentioned method, (C-1) in the case where a first detection signal having a significant difference from the reference level in one of the positive direction and the negative direction exists among the plurality of detection signals, determining that a joint corresponding to the first detection signal among the plurality of joints is in a non-joint state, (C-2) in the case where there is a second detection signal having a significant difference from the reference level in the other direction of the positive direction and the negative direction among the plurality of detection signals, determining that a joint corresponding to the second detection signal among the plurality of joints is in a broken state, (C-3) determining that a joint corresponding to a third detection signal among the plurality of joints is in a normal state when the third detection signal which does not belong to any one of the first detection signal and the second detection signal exists among the plurality of detection signals.
  2. 2. The eddy current inspection method according to claim 1, In the step (d), it comprises: (d-1) a step of preparing a preliminary substrate on the surface of which a preliminary electrode in an unbonded state is arranged; (d-2) pressing a preliminary reference region in the preliminary electrode from above to bring the preliminary reference region into close contact with the surface of the preliminary substrate, and (D-3) a step of disposing the detector in the alternating current application state above the preliminary reference region of the preliminary electrode, generating eddy currents on the surface of the preliminary reference region at the time of execution of the step (d-3), obtaining a preliminary reference signal by the eddy current measuring device, The eddy current inspection method further includes, (D-4) a step of disposing the probe in the alternating current application state sequentially above the plurality of joint portions, generating eddy currents on surfaces of the plurality of joint portions at the time of execution of the step (d-4), obtaining a plurality of preliminary detection signals corresponding to the plurality of joint portions by the eddy current measuring device, The eddy current inspection method further includes, And (d-5) determining a signal having a signal value closest to the preliminary reference signal among the plurality of preliminary detection signals as a determination preliminary detection signal, and determining a joint corresponding to the determination preliminary detection signal among the plurality of joints as the reference joint.
  3. 3. The eddy current inspection method as claimed in claim 1 or 2, The plurality of bonding portions are bonding regions bonded to the surface of the substrate by ultrasonic bonding, The thickness of each of the plurality of joint portions is 0.01mm or more.
  4. 4. The eddy current inspection method as claimed in claim 1 or 2, Each of the plurality of joint portions has a planar shape including a square having a length of one side of 1mm in plan view.
  5. 5. The eddy current inspection method as claimed in claim 1 or 2, The scanning speed of the detector performed in step (b) is 1m/s or more.
  6. 6. The eddy current inspection method as claimed in claim 1 or 2, The alternating current comprises a first alternating current and a second alternating current, and at least one of the frequencies and phases of the first alternating current and the second alternating current are different.

Description

Eddy current inspection method Technical Field The present application relates to an eddy current inspection method for inspecting an object to be inspected using an eddy current measuring apparatus with an electrode provided on a substrate. Background As inspection methods for an object to be inspected, for example, there are a first inspection method disclosed in patent document 1 and a second inspection method disclosed in patent document 2. The first inspection method is an inspection method for determining the state of an electrode lead portion based on an insulation resistance value measured between the outer surface of a metal cylinder of the electrode lead portion to be inspected and a conductive lead of the electrode lead portion. In the first inspection method, inspection can be performed even in a narrow place, and is a relatively inexpensive solder-based inspection method using an inspection device. The second inspection method uses a lead of a lead frame bonded to a substrate as an inspection object. The second inspection method includes the following first to fourth steps. The first step is to press the leads of the lead frame from above by being provided in the pressing device, and to turn on the ring-shaped lighting device. The image data obtained by the photographing is converted into a digital image signal by an a/D converter. And extracting, by the processing device, an image obtained by binarizing image data corresponding to the wire bonding portion among the image data so as to retain a portion brighter than a predetermined value. Fourth step. Determine the state of the lead based on the binarized image. By the second inspection method described above, the unbonded wire and the bonded wire can be distinguished with high accuracy. Prior art literature Patent literature Japanese patent application laid-open No. 2016-151484 (patent document 1) Patent document 2 Japanese patent laid-open No. 10-185527 Disclosure of Invention Problems to be solved by the invention However, the first inspection method described above has a problem that the inspection itself is performed without damage, but the inspection must be performed by contacting the inspection object. In the first inspection method, when the object to be inspected includes a broken portion, if the position of contact is not a broken portion but a normal portion, the presence of the broken portion cannot be detected. In addition, the second inspection method has a problem that the inspection cannot be performed without contacting the inspection object because the lead wire as the inspection object is pressurized at the time of performing the first step. In the second inspection method, although the non-joined state at the end portion of the wire can be detected in principle, there is a problem in that it is extremely difficult to determine the joined state of the intermediate region of the wire. Further, the second inspection method has a problem that the broken portion of the lead cannot be accurately identified. In the present application, an object is to provide an inspection method capable of determining a bonding state of an electrode to a substrate without contacting the electrode to be inspected, by solving the problems of the conventional inspection methods including the first and second inspection methods described above. Means for solving the problems 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 a state of the eddy current, the eddy current measuring device having a probe with a coil built in, an electrode provided on a substrate being the object to be inspected, the eddy current inspection method further comprising (a) a step of applying an alternating current to the coil in the probe to be in an alternating current application state, and (b) a step of scanning the probe in the alternating current application state along a forming direction of the electrode, the probe not being in contact with the electrode but being located above a predetermined distance from a surface of the electrode during execution of the step (b), the eddy current being generated on the surface of the electrode during execution of the step (b), the detection signal being obtained by the eddy current measuring device without interruption, the eddy current inspection method further comprising (c) a step of determining that the bonding state of the probe and the substrate is in a discrete level based on comparison of the detection signal obtained without interruption with a reference level, the bonding portion being provided with a plurality of bonding portions as a plurality of bonding portions, the bonding portion being selected from the step (d) and the bonding portion being a plurality of bonding portion bonding step, the reference level is a signal value of the detection signal when the detector is disposed above the refe