JP2012083246A - Joint inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joint inspection method for inspecting the joint state of a joint of components in an easy and accurate manner.SOLUTION: A joint inspection method for inspecting the joint state of a joint 51 using ultrasonic waves includes the following steps of: adding vibration to a vibration adding device 55 disposed in the vicinity of the joint 51 that is an object to be inspected using ultrasound waves emitted from an ultrasound wave tool 21; detecting using detecting means 31 heat or sound generated on the joint 51 by the vibration caused by the ultrasound wave transmitted from the vibration adding device 55; and outputting the joint state based on the detection data obtained from the detection means 31.

Description

  The present invention relates to a bonding inspection method capable of easily and accurately inspecting a bonding state of a component bonding portion.

  For example, in an electronic component in which a semiconductor element or the like is mounted on a substrate, a tape that is a conductor is bonded to the semiconductor element using ultrasonic vibration energy. In such a case, it is necessary to inspect the bonding of the tape. An example of the inspection method is disclosed in Patent Document 1 below. Here, a method is employed in which an electronic component mounting apparatus that mounts on a printed wiring board performs two determinations, that is, whether the state during bonding is good and whether the bonding temperature is good. For this reason, non-defective waveform data indicating the relationship between the allowable temperature of the bumps and the ultrasonic impedance is stored in advance in the electronic component mounting apparatus.

  In ultrasonic bonding, ultrasonic vibration is applied by an ultrasonic oscillator, and bonding waveform data indicating a relationship with ultrasonic impedance at the time of bonding and the like are obtained. For each joint waveform data, noise components are removed by filtering processing and compared with the good quality waveform data stored in advance. If the absolute value of the difference is greater than or equal to the preset tolerance, the joint failure Is considered. Even when the bonding waveform data does not exceed the allowable value, the bump temperature is further measured by image processing of the electronic component imaged by the infrared camera. If the bump temperature is equal to or higher than a preset allowable value, it is regarded as a bonding failure.

JP 2001-94245 A

  Such conventional bonding inspection methods have not been able to accurately identify even a gap of several μm, which cannot be determined as a bonding defect immediately. That is, the comparison by the waveform data at the time of bonding and the confirmation of the bump temperature can only confirm that the bonding is performed by the friction of the members by ultrasonic vibration. Therefore, an advanced inspection method capable of detecting even a non-bonded portion such as a gap of several μm is required.

  In particular, since inverters and the like are required to be smaller and have higher performance, tape bonding requires a higher level of bonding. In such a case, it is necessary to grasp the occurrence of a small non-joint part of several μm, but a problem that cannot be easily inspected at present, such as a destructive test, to accurately grasp the void part of such a joint part. Therefore, there is a demand for a simple inspection method at low cost.

  Accordingly, an object of the present invention is to provide a bonding inspection method for simply and accurately inspecting a bonding state of a component bonding portion in order to solve such a problem.

The bonding inspection method of the present invention is for inspecting the bonding state of a bonded portion using ultrasonic waves, and an excitation position set near the bonded portion to be inspected is obtained from an ultrasonic tool. The detection means detects heat or sound generated by the ultrasonic vibration transmitted from the excitation position, and outputs a bonding state based on the detection data obtained by the detection means. It is characterized by that.
Further, in the bonding inspection method of the present invention, it is preferable that after the bonding portion is ultrasonically bonded by the ultrasonic tool, the vibration position is vibrated by ultrasonic waves using the ultrasonic tool. .
In the bonding inspection method of the present invention, it is preferable that the frequency of the ultrasonic wave transmitted from the ultrasonic tool for exciting the vibration position is changed continuously or stepwise.
Further, the bonding inspection method of the present invention outputs the detection data obtained by the detection means for each detection data obtained according to different frequencies, or synthesizes the detection data obtained according to different frequencies. It is preferable to make it output.

Further, in the bonding inspection method of the present invention, when there are a plurality of the bonding portions, it is preferable that the bonding portions are inspected after the bonding portions are bonded.
In the bonding inspection method of the present invention, when there are a plurality of the bonding portions, it is preferable that the bonding portions are inspected by the plurality of detection means after the bonding portions are bonded.
Further, in the bonding inspection method according to the present invention, when there are a plurality of bonding portions close to each other, when one bonding portion is ultrasonically bonded by the ultrasonic tool, the one bonding portion is moved to the excitation position. As mentioned above, it is preferable to inspect the joints that have already been joined at other joints.
In the bonding inspection method of the present invention, it is preferable that the detecting means is an infrared camera, and the temperature of the bonded portion is measured by the infrared camera.
In the bonding inspection method of the present invention, it is preferable that the detection means is an AE sensor, and the sound of the bonding portion is measured by the AE sensor.

  According to the present invention, the heat and sound emitted from the non-joined portion are detected by the ultrasonic vibration applied from the ultrasonic tool, so that it is possible to detect even a void portion generated in units of several μm, and non-destructive Therefore, the cost can be reduced because of the inspection.

It is the figure which showed a part of ultrasonic bonding machine which wires a tape to a semiconductor device. It is the figure which showed the state in which the some tape was connected between the semiconductor elements and the board | substrate. It is the figure which showed notionally the joining test | inspection method of 1st Embodiment. It is the figure which showed notionally the joining test | inspection method of 2nd Embodiment. It is the figure which imaged the said frequency in the case of performing ultrasonic vibration by changing a frequency.

  Next, an embodiment of the bonding inspection method according to the present invention will be described below with reference to the drawings. Since this bonding inspection method uses an ultrasonic bonding machine used for bonding, first, the bonding in the ultrasonic bonding machine will be briefly described. FIG. 1 is a view showing a part of an ultrasonic bonding machine for wiring a tape as a conductor to a semiconductor device. The semiconductor device 10 is mounted with a semiconductor element 11 such as an IGBT, and the semiconductor element 11 is bonded to an insulating substrate 12 via a solder 13 and further bonded to a substrate 15 by a solder 14.

  The ultrasonic bonding machine is provided with a bonding head unit 20 for bonding the tape 25 to the semiconductor element 11. The bonding head unit 20 includes an ultrasonic tool 21 that applies ultrasonic vibration while pressing the tape 25 to the wiring terminal of the semiconductor element 11, and the guide 22 and the cutter 23 are disposed so as to sandwich the ultrasonic tool 21. ing. The ultrasonic bonding machine is provided with a tape supply device (not shown) in the main body 24 so that the tape 25 wound in a roll shape is set and the tape 25 having a length necessary for bonding at one place is fed out. It has become.

  The bonding head unit 20 moves horizontally in accordance with the position of the semiconductor device 10 and is positioned and lowered. As a result, the fed tape 25 is pressed against the wiring terminal of the semiconductor element 11 by the ultrasonic tool 21, and ultrasonic vibration is applied with the ultrasonic tool 21 pressing the tape 25. Then, the welding surface between the bonding surfaces of the objects to be bonded, that is, the contact surface between the wiring terminal of the semiconductor element 11 and the tape 25 slides at a high frequency, and welding which is melted by the frictional heat is performed.

  In the semiconductor device 1, for example, as shown in FIG. 2, a plurality of tapes 25 (25 a, 25 b, 25 c) are connected to the semiconductor element 11 between the substrate 18 and both are electrically connected. Accordingly, the three tapes 25a, 25b, and 25c are joined by the ultrasonic tool 21 being pressed by the respective joining portions in order and subjected to ultrasonic vibration.

  Next, a description will be given of a method for inspecting the joining of the component joints thus ultrasonically joined. FIG. 3 is a diagram conceptually illustrating the bonding inspection method according to the first embodiment. In this bonding inspection method, in addition to the ultrasonic bonding machine used for ultrasonic bonding, an infrared camera 31 for detecting the temperature of the bonded portion and image processing based on detection data obtained by the infrared camera 31 are performed. An arithmetic unit 32 is used. The infrared camera 31 is configured to be horizontally movable by a moving means (not shown) so that the temperature of the joint portion to be inspected can be measured.

  In the bonding inspection method of the present embodiment, ultrasonic vibration is applied to a portion different from the bonding portion 51 that is the inspection target portion, and the gap portion 52 and the incomplete bonding portion 53 (drawing) are generated by ultrasonic vibration energy received indirectly. Is expressed by a thin chain line). Therefore, as described above, the ultrasonic tool 21 after the ultrasonic bonding is finished is disposed at the excitation position 55 set in the vicinity of the bonding portion 51. The vibration position 55 is provided on the semiconductor element 11 side that receives pressure from the ultrasonic tool 21 so that ultrasonic energy is transmitted to the bonding portion 51 of the object to be bonded.

  At the vibration position 55, ultrasonic waves are transmitted from the ultrasonic tool 21 that is not in contact with the semiconductor element 11. The ultrasonic vibration energy applied to the semiconductor element 11 is transmitted from the excitation position 55 to the joint 51. In the joint portion 51, when the gap portion 52 and the incomplete joint portion 53 are generated, the tape 25 and the semiconductor element 11 rub against each other due to the transmitted vibration and generate heat. On the other hand, since heat is not generated at the joining portion 54 where the tape 25 and the semiconductor element 11 are sufficiently joined, heat is not generated.

  In the infrared camera 31, the temperature at each location generated in the joint 51 is measured, and the detected data is sent to the arithmetic device 32. The arithmetic device 32 creates a temperature distribution image of the joint 51 based on the temperature detection data and displays it on the monitor. At the place where the gap 52 and the incompletely joined part 53 are generated, the state where the temperature is increased due to heat generation is displayed by color coding, and the part that is not joined and its size can be confirmed.

  For example, the three tapes 25a, 25b, and 25c shown in FIG. 2 are joined at a plurality of locations, but only the joint 51 (51a, 51b, 51c) with the semiconductor element 21 is picked up and tested. The procedure will be described. First, ultrasonic bonding is performed on the three tapes 25a, 25b, and 25c. Thereafter, ultrasonic waves are applied from the ultrasonic tool 21 to the vicinity of the joint portions 51a, 51b, and 51c, and temperature measurement is performed by the infrared camera 31 for each. In other words, the present embodiment proposes a bonding inspection method in which bonding inspection is incorporated in the ultrasonic bonding process, but a method is proposed in which ultrasonic bonding and bonding inspection are performed separately.

  On the other hand, ultrasonic bonding and bonding inspection can be performed at the same time as long as the bonding locations are close as in the bonding portions 51a, 51b, and 51c. That is, when the ultrasonic bonding is performed in the order of the bonding portions 51a, 51b, and 51c, the ultrasonic energy applied from the ultrasonic tool 21 for ultrasonic bonding of the bonding portion 51b is adjacent to the bonded portions. Is also transmitted to the joint portion 51a, causing vibration. At this time, the infrared camera 31 is installed on the joined portion 51a after joining and a joining inspection is performed.

  According to the bonding inspection method of the present embodiment, it is possible to detect the gap portion 52 and the incompletely bonded portion 53 of the bonding portion generated in units of several μm by the ultrasonic vibration applied from the ultrasonic tool 21. Moreover, since the tape 25 is bonded to the semiconductor element 11 by the ultrasonic tool 21 and then continuously performed using the same ultrasonic tool 21, the bonding inspection can be simplified and the cost can be reduced. In particular, when other parts are jointly inspected by using ultrasonic vibration transmitted from other parts when joining other parts, the working efficiency can be further improved.

(Second Embodiment)
Next, FIG. 4 is a diagram conceptually showing the bonding inspection method of the second embodiment. In this bonding inspection method, in addition to the ultrasonic bonding machine used for ultrasonic bonding, an acoustic emission sensor (hereinafter referred to as “AE sensor”) 33 for detecting a sound signal (AE signal) generated at the bonded portion. And the arithmetic unit 32 which performs data processing based on the AE signal obtained from the AE sensor 33 is used. In the joining inspection of this embodiment, since it is necessary to receive an AE signal generated in a very narrow region, a conical vibration transmitting jig 34 is integrally formed on the AE sensor 33. The vibration transmitting jig 34 is made of a material having fine crystal particles and little acoustic attenuation.

  When the vibration transmitting jig 34 is not in contact with the joint 51, the AE signal transmitted to the AE sensor 33 by the air layer is greatly attenuated. Therefore, a dryer plant 35 made of silicon rubber or a resin sheet is attached to the tip of the vibration transmitting jig 34. As a result, the attenuation of the received AE signal can be suppressed, the damage to the semiconductor element 11 to which the AE sensor 33 is applied can be reduced, and it can be repeatedly adhered to the joints 51 at a plurality of locations. The AE sensor 33 is supported by moving means (not shown) so that the dryer plant 35 can be applied to the predetermined joint 51. Note that the dryer plant 35 is not necessarily attached when the effect is not required.

  Therefore, also in the present embodiment, the ultrasonic tool 21 is disposed at the vibration position 55 different from the joint portion 51 and ultrasonic waves are transmitted, so that the ultrasonic vibration energy is indirectly transmitted to the joint portion 51. Given. The joint 51 is vibrated by a given ultrasonic wave, and an AE signal generated therefrom is received by the AE sensor 33. When the gap portion 52, the incompletely joined portion 53, or the like exists in the joint portion 51, an AE signal that does not occur at the joint portion 54 is obtained. In the arithmetic unit 32, the waveform of the AE signal is displayed on the monitor, and the judgment of the joining state is shown by comparison with the waveform of the AE signal generated by non-joining or normal joining such as the gap 52 stored in advance.

  Also in this bonding inspection method, when the object shown in FIG. 2 is an inspection object, as a procedure thereof, after performing ultrasonic bonding on the three tapes 25, bonding inspection of the bonding portions 51a, 51b, and 51c is performed. Alternatively, ultrasonic bonding with respect to one bonding portion 51b and bonding inspection with respect to another bonding portion 51a may be performed simultaneously.

  Therefore, according to the present embodiment, it is also possible to detect the gap portion 52 and the incompletely bonded portion 53 of the bonded portion generated in units of several μm by the ultrasonic vibration applied from the ultrasonic tool 21. Moreover, since the tape 25 is bonded to the semiconductor element 11 by the ultrasonic tool 21 and then continuously performed using the same ultrasonic tool 21, the bonding inspection can be simplified and the cost can be reduced. In particular, when other parts are jointly inspected by using ultrasonic vibration transmitted from other parts when joining other parts, the working efficiency can be further improved.

  Next, changing the frequency of the ultrasonic wave output from the ultrasonic tool 21 when executing the bonding inspection method according to the first and second embodiments will be described. Here, FIG. 5 is a diagram illustrating the frequency when the ultrasonic vibration is performed by changing the frequency. When the ultrasonic frequency (wavelength) is changed, heat or sound can be generated due to the difference in the gap 52 or the incompletely bonded portion 53 or the size of the non-bonded portion. Therefore, in the first and second embodiments, it is effective to perform the joining inspection by changing the ultrasonic frequency. At that time, there are a case where the ultrasonic frequency is continuously changed as shown in FIG. 5A and a case where the ultrasonic frequency is changed stepwise as shown in FIG.

  When the ultrasonic frequency is continuously changed as shown in FIG. 5 (a), it is possible to perform a joint inspection with a plurality of frequencies in a short time, but it is difficult to analyze each frequency, for example, it is difficult to separate infrared images. . On the other hand, when the ultrasonic frequency is changed stepwise as shown in FIG. 5 (b), it takes time for the joint inspection as the frequency change increases, but detection data can be easily separated. Accordingly, since each has advantages and disadvantages, any one may be selected according to the situation.

  As the non-joint part of the joint part 51, the gap part 52 and the incomplete joint part 53 can be considered. For example, the imperfect joint part 53 is vibrated at a relatively high frequency of 40 kHz, and generates heat and sound due to rubbing. Let On the other hand, the air gap 52 is vibrated at a relatively low frequency of 10 kHz, for example, and generates heat and noise due to rubbing. Therefore, for example, the inspection is performed by changing the frequency continuously or stepwise between 10 to 100 kHz.

  Thereby, it is possible to acquire different inspection data depending on the distinction between the gap portion 52 and the incompletely joined portion 53 and the size of the non-joined portion corresponding to the changing frequency. For example, in 1st Embodiment which measures temperature with the infrared sensor 33, the non-joining location which exists in the junction part 51 heat | fever-generates one by one because a frequency changes. In the intermittent case shown in FIG. 5B, temperature data for each frequency is acquired, and in the continuous case shown in FIG. 5A, temperature data divided in a certain frequency region is acquired.

  And in the arithmetic unit 32, the temperature distribution screen of the joint part 51 is displayed on the monitor. At this time, if a temperature distribution image is created for each temperature data, the inspection results divided for each state of the non-joint part are displayed. Obtainable. On the other hand, if each temperature data is synthesized, one inspection result can be obtained. At that time, the inspection result that distinguishes the state of the non-joined portion is displayed by color-coding the display of the heat generation point for each temperature data. Output. Also in the second embodiment using the AE sensor 33, when the frequency is changed, the inspection data may be output for each inspection data or the combined inspection result.

As mentioned above, although embodiment was described about the joining test | inspection method concerning this invention, this invention is not limited to this, A various change is possible in the range which does not deviate from the meaning.
In the above-described embodiment, the case where one place is inspected by the infrared sensor 31 or the AE sensor 33 has been described. You may make it test | inspect the junction part 51. FIG. For example, it is possible to arrange the infrared sensor 31 and the AE sensor 33 for each of the joint portions 51a, 51b, and 51c shown in FIG.

DESCRIPTION OF SYMBOLS 10 Semiconductor device 11 Semiconductor element 21 Ultrasonic tool 25 Tape 31 Infrared camera 32 Arithmetic device 33 AE sensor

Claims (9)

In the joint inspection method for inspecting the joint state of the joint using ultrasonic waves,
The vibration position set near the joint to be inspected is vibrated with ultrasonic waves from an ultrasonic tool,
The detection means detects the heat or sound generated in the joint by vibration caused by ultrasonic waves transmitted from the excitation position,
A bonding inspection method characterized in that a bonding state is output based on detection data obtained by the detection means. In the joining inspection method according to claim 1,
A joining inspection method, wherein after the joining portion is ultrasonically joined by the ultrasonic tool, the vibration position is vibrated by an ultrasonic wave using the ultrasonic tool. In the joining inspection method according to claim 1 or claim 2,
A bonding inspection method characterized in that the frequency of an ultrasonic wave transmitted from the ultrasonic tool that vibrates an excitation position is changed continuously or stepwise. In the joining inspection method according to claim 3,
The detection data obtained by the detection means is output for each detection data obtained according to different frequencies, or the detection data obtained according to different frequencies is synthesized and output. Bonding inspection method. In the joining inspection method according to any one of claims 1 to 4,
A joining inspection method, wherein, when there are a plurality of the joining portions, the joining portions are inspected after joining the joining portions. In the joining inspection method according to claim 5,
A joining inspection method characterized in that, when there are a plurality of joining portions, each joining portion is inspected by the plurality of detection means after joining the joining portions. In the joining inspection method according to any one of claims 1 to 4,
When there are a plurality of joints in the vicinity, when one joint is ultrasonically joined by the ultrasonic tool, the joint is already finished at the other joint using the one joint as the excitation position. A bonding inspection method characterized in that an inspection is performed on a bonded portion. In the joining inspection method according to any one of claims 1 to 7,
The joint inspection method, wherein the detection means is an infrared camera, and the temperature of the joint is measured by the infrared camera. In the joining inspection method according to any one of claims 1 to 7,
The joint inspection method, wherein the detection means is an AE sensor, and the sound of the joint is measured by the AE sensor.

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