JP2859675B2 - Wire bonding inspection method and wire bonding apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wire bonding inspection method and a wire bonding apparatus in a process of assembling a semiconductor integrated circuit (IC) or the like.

[Background Art] When manufacturing a semiconductor integrated circuit (IC) or a large-scale integrated circuit (LSI), a lead frame on which semiconductor pellets are provided is positioned by a transfer device, and then a tool for holding wires is mounted on the lead frame. By displacing the wire relatively to the semiconductor pellet, the wire is guided to the lead post provided on the lead frame and the pad of the semiconductor pellet, respectively, and bonded. Inspection of the loop shape of the wire connected to the lead post of the lead frame and the pad of the semiconductor pellet bonded by such a process, whether the wire is securely connected, and the like are conventionally performed by extraction immediately after wire bonding. ing. In this inspection, the inspector stops the wire bonding device and carefully removes the lead frame housed in the magazine from the magazine and uses a microscope to visually check the loop shape of the wire and whether the wire is correctly bonded and connected The inspection method is adopted.

[Problems to be Solved by the Invention] However, in the conventional wire bonding inspection method, the inspector stops the wire bonding apparatus for inspecting the lead frame, removes the lead frame from the magazine, inspects the lead frame, and then again. Since the lead frame is stored back in the magazine, there are drawbacks such as giving an impact to the lead frame during transportation of the lead frame or causing the lead frame to come into contact with other objects to break the wire shape. Further, in the conventional inspection method, there is a disadvantage that the wire bonding apparatus must be stopped for the inspection, so that the working efficiency is reduced.

The present invention has been made in view of the above-mentioned disadvantages of the prior art,
There is no need to take out the lead frame from the magazine for inspection, and even when the wire bonding apparatus is operating, the inspector can project the image of the bonded lead frame on the video device and perform the inspection when inspecting. An object of the present invention is to provide a wire bonding inspection method and a wire bonding apparatus.

Means for Solving the Problems The present invention conveys a lead frame, on which a plurality of semiconductor pellets are arranged, to a bonding stage by intermittently conveying one frame of the semiconductor pellet to a bonding stage, and conveys the lead frame by the conveying means. A tool for positioning and positioning the lead frame and holding the wire is displaced relative to the lead frame and the semiconductor pellet, and the wire is moved to a lead post provided on the lead frame and a pad on the semiconductor pellet, respectively. Bonding means for guiding and bonding, a magazine for accommodating the lead frame bonded by the bonding means, at least one or more imaging means provided between the bonding means and the storage magazine; Plural semiconductor pellets and lead ports An image memory for imaging a wire connected between a pad on the semiconductor pellet and a lead post from an arbitrary specific portion by the imaging means and writing and reading only a specific number of frames. An image storage / reproduction means, and a display means for reading and displaying an image stored from the image memory of the image storage / reproduction means. A plurality of semiconductor pellets, lead posts, and wires connected between the pads on the semiconductor pellets and the lead posts of the bonded lead frame which are intermittently sent are imaged from any specific place by the imaging means and the image is taken. Are sequentially stored in the image memory for a specific number of frames, and the stored image is read out from the image memory, and It is intended to be displayed in the shows means.

Also, the present invention provides a transfer unit capable of intermittently transferring a lead frame on which a plurality of semiconductor pellets are disposed to a bonding stage one frame of the semiconductor pellet, and positioning the lead frame transferred by the transfer unit. The tool holding the wire is displaced relative to the lead frame and the semiconductor pellet by the XY stage, and the wire is guided to the lead post provided on the lead frame and the pad on the semiconductor pellet, respectively, for bonding. A bonding means for performing, a movable imaging means arranged in proximity to the bonding means, a magazine for accommodating a lead frame bonded by the bonding means, a plurality of semiconductor pellets arranged on the lead frame, a lead post, A pad on the semiconductor pellet and An image storing and reproducing unit having an image memory for writing the read of the image captured by the imaging means connected wires between Doposuto,
Display means for reading out and displaying the stored image from the image memory of the image storage / reproduction means, and instructing the image storage / reproduction means to start image storage and setting the number and frame position of the lead frame in which the image is to be stored A wire bonding control device, and a lead frame number of a bonded lead frame and a frame of a semiconductor pellet mounted on the lead frame in response to an image storage start command from the wire bonding control device to the image storage / reproduction means. The control means in the image storage / reproduction means determines whether or not the position matches the preset lead frame number and the frame position of the semiconductor pellet disposed on the lead frame. The number of the lead frame and the core of the semiconductor pellet provided on the lead frame. If the positions match, the imaging unit is moved and positioned at a preset lead frame number and frame position to take an image, and the taken image is stored in the image memory. An image is read from the image memory and displayed on the display means.

Further, according to the present invention, the image stored in the image memory can be read out and written to another storage medium.

Further, according to the present invention, an image stored in the image memory can be read and read out and reproduced by another image storage / reproduction device via a communication unit.

Further, the image memory of the present invention stores an entire image and / or an image of a part of the semiconductor pellet, the lead post, and the wire bonded and connected between the pad on the semiconductor pellet and the lead post. Things.

Further, according to the present invention, an image storage start command and a number of a lead frame in which an image is to be stored are provided to the image storage / reproduction means by a wire bonding control device for performing a command control of various operations of the wire bonding apparatus, and the lead frame is provided in the lead frame. Setting a frame position of a semiconductor pellet to be carried out, a step of intermittently conveying a lead frame on which a plurality of semiconductor pellets are disposed to a bonding stage by a conveying means, one frame of the semiconductor pellet, and the conveying means A tool for positioning the lead frame conveyed by and displacing the tool relative to the lead frame and the semiconductor pellet by an XY stage with respect to the lead frame and the semiconductor pellet, and disposing the wire on the lead frame and the semiconductor pellet. A process that performs bonding by guiding each to the upper pad A lead frame in which the number of the lead frame of the bonded lead frame and the frame position of the semiconductor pellet disposed on the lead frame are set in advance by an image storage start command from the wire bonding control device to the image storage / reproduction means. And determining whether or not the frame number and the frame position of the semiconductor pellet provided on the lead frame coincide with each other by the control means in the image storage / reproduction means. When the number and the frame position of the semiconductor pellet provided on the lead frame match, the preset lead frame number and the frame position of the semiconductor pellet provided with the lead frame are referred to as the frame positions. The imaging means is moved and positioned to take an image, and the taken image is stored in the image memory. The stored image is read out from the image memory and displayed on the display means.

Example Next, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a wire bonding apparatus used in this embodiment.

In FIG. 1, a bonding head 1 is mounted on an XY table (not shown) movable in the X and Y directions, and is relatively moved in the X and Y directions for positioning. A wire bonding connection is made between the lead post and the pad on the semiconductor pellet. The lead frame 4 on which a plurality of semiconductor pellets are arranged is stored in a supply side magazine 5, and the lead frame 4 stored in the magazine 5 is sent out onto the transport device 3. The magazine 5 is configured to be vertically movable intermittently by lifting means (not shown), so that the lead frame 4 can be sequentially sent out onto the transport device 3. The lead frame 4 sent out onto the transfer device 3 is intermittently sent one frame at a time below the bonding arm of the bonding head 1 while being detected by a sensor (not shown) and regulated in the width direction by guide means (not shown). Can be When the lead frame 4 reaches the bonding stage for performing the bonding operation, the lead frame 4 is detected by a sensor (not shown).
Is detected, the lead post of the lead frame and the pad on the semiconductor pellet are relatively positioned, and the bonding head 1 makes a bonding connection by a wire. The lead frame 4 connected by bonding is intermittently fed one frame at a time and wire-bonded sequentially, and then stored in the storage magazine 2. The storage magazine 2 is also configured to be vertically movable intermittently by lifting means (not shown), and is configured to sequentially store the lead frames 4 connected by bonding. Usually, a plurality of semiconductor pellets are disposed on the lead frame 4. In the apparatus shown in FIG. 1, a TV camera 6 separate from an image pickup device (not shown) such as a TV camera mounted on the bonding head 1 for performing image processing and the like mounted between the bonding head 1 and the storage magazine 2. , An optical lens 7, an illumination lamp 8, and the like. A sensor (not shown) such as a known optical sensor for detecting the presence or absence of the lead frame 4 is provided below the optical lens 7 of the image pickup apparatus. The TV camera 6 is configured to be able to perform processing based on a binarized signal in addition to processing of a normal television signal. The video signal from the TV camera 6 is input to an image storage / reproduction device 9 having a built-in image memory. FIG. 2 is a block diagram showing a circuit configuration of the image storage / reproduction device 9. As shown in FIG.

In the figure, an image picked up by an image pickup device such as a TV camera 6 is converted from an analog signal to a digital signal by an A / D converter 12 and stored in an image memory 14. The control of the timing of writing and reading of an image to and from the image memory 14 is performed by a control circuit 15. Image memory 14
Is a memory that can be written and read at any time, and can store one frame. Since the image memory 14 includes a plurality of frame memories, images of a plurality of frames (semiconductor chips) can be stored in the present embodiment. Various control commands are issued to the image storage / reproduction device 9.
CPU 16 and floppy disk control 17, communication control 18, key control 19, input / output control
20 are provided. Floppy disk control
Reference numeral 17 denotes a control circuit for recording the image stored in the image memory 14 on an external magnetic storage medium such as a floppy disk, and a communication control 18 connects to a communication line such as a telephone line to connect to an external image processing device. This is a control circuit for transmitting an image stored in the image storage / reproduction device 9 via a communication line. The key control 19 is an operating means for the operator to load an image to be stored by the image storage / reproduction device 9 into the image memory 14, and the input / output control 20 is connected to the wire bonding control device 11 shown in FIG. It is connected to input / output commands such as an image storage start command in response to a command from the wire bonding control device 11 side. This wire bonding control device 11
Is provided with a key control (not shown) for performing various operations of the wire bonding apparatus. The required number of frames to be stored in advance in the image memory 14 in the image storage / reproduction apparatus 9 is required. Etc. can be set. The stored image can be recorded on an external storage medium such as a floppy disk, and the stored image can be transmitted to an external image processing device via a communication line by connecting to a communication line. It is configured as follows. When the operator needs to inspect the result of wire bonding, the image storage / reproduction device 9
An image of the bonded lead frame stored therein is displayed on a television monitor 10 as a display means for inspection.

Next, the operation of the present embodiment having the above configuration will be described.

The lead frame 4 sent out from the supply side magazine 5 onto the transport device 3 is intermittently fed one frame at a time after being bonded by the bonding head 1. Lead frame 4 bonded by this bonding head 1
Is located below the image pickup device including the TV camera 6 and the like.
For example, a semiconductor pellet 5 disposed on a lead frame
In order to store an image of a frame, the necessary number of frames is set in the wire bonding control device 11 in advance. After the lead frame is conveyed, the wire bonding control device 11 sends a storage start signal to the image storage / reproduction device 9 and transmits a signal of the imaging device.
The data is converted by the A / D converter 12 and stored in the image memory 14. As a result, the lead post of the lead frame and the pad on the semiconductor pellet are intermittently sent after being bonded and connected by a wire, so that an image for five frames preset by the image memory is automatically stored. Is done.

In order for the inspector to inspect the wire bonding on the wire bonding apparatus, a reproduction switch (not shown) provided in the key control 19 of the image storage / reproduction apparatus 9
Is pressed to retrieve the image of the necessary frame from the image memory 14. At this time, the image stored in the image memory 14 by the D / A converter 13 is converted from a digital signal to an analog signal, and the image is instantly displayed on the television monitor 10. Since the same image is displayed on the television monitor 10 until the reproduction switch is pressed again, the image can be confirmed on the monitor until the necessary inspection by the inspector is completed. If it is not necessary to inspect this image immediately, the image can be stored in an external storage medium such as a floppy disk via the floppy disk control 17, or can be stored in an external image processing device using a communication line via the communication control 18. The inspection can be performed by sending the image to the user when necessary. By doing so, the already written image can be erased and a new image can be written to the memory. Also, by changing the field of view of the optical lens by changing the magnification of the optical lens depending on the inspection content, or by installing at least one or more imaging devices, as shown in FIG. It is also possible to store an entire image and / or an image of a part of the lead posts and the wires wound around them. By changing the field of view of the optical lens in this manner, it is possible to easily confirm whether or not the wire bonding connection has been securely performed. For example, if a part corresponding to the whole image is magnified and displayed after taking the whole image, the connection state of the wire can be immediately determined.

Next, a method of counting the number of lead frames and the number of frames using the apparatus having the configuration of the above embodiment will be described. A sensor (not shown) for detecting a lead frame is provided in the vicinity of the supply side magazine 5 on the transporting device 3, and a counter (not shown) for counting the number of lead frames detected by the sensor is provided. It is provided in the wire bonding control device 11. Sensors for detecting the lead frame 4 are also provided below the bonding stage position on the transport device 3 and below the optical lens 7 of the imaging device.

First, assume that the number of frames of the lead frame is A. Here, it is assumed that A = 6 as shown in FIG.

Next, using the flowchart shown in FIG. 4, a magazine 5 containing the lead frame 4 is set on the supply side of the wire bonding apparatus shown in FIG. ₁ (step S ₁ ). When the first frame of the lead frame 4 sent out from the magazine 5 onto the transfer device 3 is detected by a sensor (not shown) provided in the transfer device 3 (step S ₂ ), the wire bonding control is performed. The counter in the device 11 sets the number F of the lead frames 4 to 1 and sets the number K of frames of the lead frame 4 to 0 (step S ₃ ). Next, the lead frame 4 is conveyed on the one frame by one conveying device 3 after was (Step S _4), whether there is a lead frame 4 is determined on the bonding stage (Step S _5). When there is no lead frame 4 on the bonding stage, that is, when the lead frame 4 that has already been bonded is located at the imaging position even if there is a case where there is one frame between the lead frames. There is. Thus, the lead frame 4 in step S ₉ it is determined whether there is an imaging position because in this case it is necessary to count the number of frames of the lead frame 4 or the like. If shifts the conveying of the lead frame 4 returns to step S ₄ in the case where there is no lead frame 4 in this imaging position do the next step.

Then, if there is a lead frame 4 on the bonding stage, like conventional wire bonding performed wire bonding is performed pellets of position detection (step S ₆₎ (Step S _7), all in step S ₈ It is determined whether the wire bonding has been completed. If not completed continuously performed the step S _7, when it is finished it is determined whether there is a lead frame 4 to the imaging position (Step S _9). Here Repeat step returns to step S ₄ in the case where there is no lead frame 4, it sets the K ← K + 1 and proceeds to step S ₁₀ if there is a lead frame 4. Here since if because it is A = 6 is K> A in step S ₁₁ following the lead frame 4 will have been set on the image pickup position F ← F +
1, K ← 1 is set (step S ₁₂ ). However, if not K> A in step S _11, since the new lead frame 4 is that it has not been set on the imaging position, the lead frame and proceeds to step S ₁₃ without performing the setting in step S ₁₂ It is determined whether the number 4 and the frame position match. Match to if you have not yet and sends it to the storage magazine 2 performs the conveyance of the lead frame the process proceeds to step S _4. If they match, the image storage / reproduction device 9
The memory start signal output from the wire bonding controller 11 to send a (step S ₁₄₎ and the image storage (step S ₁₅₎ and storing magazine 2 proceeds to the transport process of the lead frame in step S _4.

It also shifts the process of step S ₁₃ to step S ₁₅ when the setting of the step S ₁₂ is made.

Since the number of lead frames and the number of frames can be counted and stored in the image by the above steps, the number M and the number N of frames of the lead frame 4 to be stored in the image by the wire bonding control device 11 are set in advance. Thus, the predetermined lead frame 4 number M and frame number N can be automatically stored using the apparatus shown in FIG.

Next, in the device shown in FIG. 1, an image pickup device including a TV camera 6, an optical lens 7, and an illumination lamp 8 is used, but the image pickup device is mounted on the bonding head 1 without using such another image pickup device. The image of the lead frame 4 can be stored using an image pickup device having the same function as the image pickup device including the TV camera 6, the optical lens 7, and the like. This will be described with reference to the flowchart of FIG. The rest of the configuration is the same as that of FIG.

First, a number M and a frame position N of a lead frame in which an image is to be stored are set in the wire bonding control device 11 in advance. This setting can be performed multiple times. Next, the position of an image to be stored on the XY stage on which the bonding head 1 is mounted is stored in the wire bonding control device 11. This is because an image of the bonding connection state is taken after the XY stage has moved and the bonding operation has been performed, and therefore the position to be imaged needs to be stored as a position on the coordinates of the XY stage.

When the start command from the wire bonding controller 11 is issued as shown in FIG. 6, the position of the pellet is detected in step SA _1. Wire bonding is performed at Step SA _2, whether the wire bonding has been finished is determined in step SA _3. In this wire bonding has not flow returns to the previous step, determining whether the position of the number M and the frame N of the lead frame which is previously set in step SA ₄ If the bonding is completed are matched Is done. If they do not match, the process proceeds to step SA ₈ for conveying the lead frame. Here, the number F of the lead frames 4 is counted by the counter, and the number K of the frames of the lead frame 4 is also counted. Therefore, it is determined whether or not F = M and K = N. If this number and the number of frames of the lead frame 4 in Step SA ₄ are coincident positions by moving the XY stage in an image storage location. Since this image storage device is stored as coordinate points of the XY table, an image storage start command signal is issued to the image storage / reproduction device 9 after this movement (SA ₆ ), and the image is stored (SA ₇ ). . After storage of the image is completed to convey the lead frame (SA _8). The same process as the process returns to step SA ₁ After this conveyance is made is repeated.

As described above, since the image of the lead frame 4 number and frame position set in advance by the command from the wire bonding control device 11 has been stored in the image memory 14 of the image storage / reproduction device 9, the connection state of the wire bonding is determined. When the inspector wants to inspect, the desired image can be called out from the memory and displayed on the television monitor 10 by operating the reproduction switch provided in the operation means of the key control 19. The quality of the wire bonding can be determined by inspecting the displayed image.

In this embodiment, the image storage / reproduction device 9 and the wire bonding control device 11 have different configurations, but may be configured integrally.

[Effects of the Invention] As described above, according to the present invention, it is not necessary for the inspector to stop the wire bonding apparatus for inspecting the lead frame, and even if the wire bonding apparatus is operating, the inspected lead frame can be used. Since the inspection can be performed by projecting the image on the video device, there is an effect that the wire shape is not broken by applying an impact to the lead frame or contacting another lead frame. Further, according to the present invention, it is not necessary to stop the wire bonding apparatus for the inspection, so that there is an effect that the working efficiency is improved. In addition, since a plurality of images can be stored, the connection status of wire bonding can be displayed on a video to perform a comparative inspection or the like, so that quality control can be improved.

[Brief description of the drawings]

FIG. 1 is an embodiment of the present invention, showing a wire bonding apparatus used in the present invention, FIG. 2 is a block diagram of the image storage / reproduction apparatus shown in FIG. 1, and FIG. FIG. 4 is a view showing a whole image and a partial image stored in an image memory shown in FIG. 4, FIG. 4 is a flowchart for explaining a method of counting the number of lead frames and the number of frames according to the present invention and storing the image, and FIG. FIG. 6 is a flow chart showing a method for automatically detecting the number and frame position of a lead frame using the wire bonding control device according to the present invention and storing it in an image memory. 1 ... bonding head, 2 ... storage magazine, 3 ...
... Conveying device, 4 ... Lead frame, 5 ... Supply magazine, 6 ... TV camera, 7 ... Optical lens, 8 ... Illumination light, 9 ... Image storage / reproduction device, 10 ... TV monitor, 11
…… Wire bonding controller, 12 …… A / D converter, 1
3 ... D / A converter, 14 ... Image memory, 15 ... Control circuit,
16 ... CPU, 17 ... Floppy disk control, 1
8: Communication control, 19: Key control, 20
...... Input / output control.

Claims (6)

(57) [Claims] A lead frame on which a plurality of semiconductor pellets are disposed; a transfer means capable of intermittently transferring one frame of the semiconductor pellet to a bonding stage; and positioning the lead frame transferred by the transfer means. Bonding means for performing bonding by displacing a tool for holding a wire relatively to the lead frame and the semiconductor pellet and guiding the wire to a lead post provided on the lead frame and a pad on the semiconductor pellet, respectively; A magazine for accommodating the lead frame bonded by the bonding means; at least one or more imaging means provided between the bonding means and the storage magazine; and a plurality of semiconductor pellets disposed on the lead frame , Lead post, on the semiconductor pellet An image storage / reproducing unit having an image memory for imaging a wire connected between the pad and the lead post from an arbitrary specific portion by the imaging unit and writing and reading only a specific number of frames of images; Display means for reading out and displaying an image stored from the image memory of the image storage / reproduction means, wherein the bonding is intermittently sent one by one by the transport means in response to an image storage start instruction to the image storage / reproduction means. A plurality of semiconductor pellets, a lead post, and a wire connected between a pad on the semiconductor pellet and the lead post of the completed lead frame are imaged from an arbitrary specific portion by the imaging means, and the image is specified in the image memory. And sequentially reading out the stored images from the image memory and displaying them on the display means. Wire bonding apparatus according to claim. 2. A transfer means capable of intermittently transferring a lead frame on which a plurality of semiconductor pellets are provided to a bonding stage one frame of the semiconductor pellet, and positioning the lead frame transferred by the transfer means. Bonding is performed by displacing the tool holding the wire relatively to the lead frame and the semiconductor pellet by the XY stage and guiding the wire to the lead post provided on the lead frame and the pad on the semiconductor pellet, respectively. A bonding unit, a movable imaging unit disposed in proximity to the bonding unit, a magazine for accommodating the lead frame bonded by the bonding unit, a plurality of semiconductor pellets disposed on the lead frame, a lead post, Pads and holes on semiconductor pellets An image storage / reproducing unit having an image memory for writing and reading the image by capturing an image of the wire connected to the post post by the image capturing unit; and reading an image stored from the image memory of the image storage / reproducing unit. A wire bonding control device for performing an image storage start command to the image storage / reproduction device and setting a lead frame number and a frame position in which an image is to be stored. A lead frame number of a bonded lead frame and a frame position of a semiconductor pellet disposed on the lead frame are set in advance by a lead frame number and a lead frame number in accordance with an image storage start command to the image storage / reproduction means. Whether the position of the top of the placed semiconductor pellet matches A determination is made by the control means in the image storage / reproduction means. If the determination result shows that the number of the lead frame and the frame position of the semiconductor pellet provided on the lead frame match, a predetermined lead is set. Moving the imaging means to the frame number and frame position to take an image, storing the captured image in the image memory, reading the stored image from the image memory, and displaying the image on the display means. Characteristic wire bonding equipment. 3. The wire bonding apparatus according to claim 1, wherein an image stored in the image memory can be read and written to another storage medium. 4. The wire according to claim 1, wherein the image stored in the image memory can be read out and read out and reproduced by another image storage / reproduction device via a communication unit. Bonding equipment. 5. The image memory stores an entire image and / or an image of a part of the semiconductor pellet, the lead post, and a wire bonded and connected between a pad on the semiconductor pellet and the lead post. The wire bonding apparatus according to at least one of claims 1 to 4, wherein 6. An image storage start command, a number of a lead frame in which an image is to be stored in the image storage / reproduction means, and a wire bonding control device for controlling the operation of various operations of the wire bonding apparatus. A step of setting a frame position of a semiconductor pellet, a step of intermittently conveying the semiconductor pellets one by one to a bonding stage by a conveying means, and a step of conveying a lead frame on which a plurality of semiconductor pellets are disposed, by the conveying means A tool for positioning the transported lead frame and holding the wire is displaced relative to the lead frame and the semiconductor pellet by the XY stage, and the wire is provided on the lead post provided on the lead frame and the semiconductor pellet. And bonding to each of the pads. According to an image storage start command from the wire bonding control device to the image storage / reproduction means, a lead frame number of a bonded lead frame and a frame position of a semiconductor pellet disposed on the lead frame are set in advance for a lead frame. Determining by the control means in the image storage / reproducing means whether or not the number and the frame position of the semiconductor pellet provided on the lead frame coincide with each other. When the frame position of the semiconductor pellet provided on the lead frame matches the frame position of the semiconductor pellet provided on the lead frame, the imaging is performed at a preset lead frame number and the frame position of the semiconductor pellet provided with the lead frame. Move and position the means and take an image,
Storing the captured image in the image memory; reading the stored image from the image memory; and displaying the read image on a display unit.