JP2002151895A - Electronic component mounting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component mounting method capable of stably recognizing a bump forming surface. SOLUTION: In the mounting method for mounting an electronic component 13 on a substrate by joining bumps 13a of the component 13 to electrodes of the substrate, flattening is performed, in which a suction nozzle 7a holding the component 13 is lowered, with respect to a flattening stage 10 to make the bottom surface of the bumps 13a uniform in height, and then the nozzle 7a holding the component 13 is moved to a recognition section 11 for recognizing the flat surface of the bottom end portions of the bumps 13a by a line camera 11a from below. Thus, variation in the states of bumps 13a can be eliminated, and stable recognition can be carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting an electronic component having a bump, such as a flip chip, on a substrate.

[0002]

2. Description of the Related Art As a kind of electronic parts, electronic parts with bumps such as flip chips provided with bumps for external bonding are known. When mounting this electronic component on a substrate, the bumps provided on the lower surface of the electronic component are joined to the connection electrodes of the substrate by soldering or using a conductive paste containing conductive particles in a resin adhesive. I do. In this mounting operation process, identification and position detection of the electronic component are performed by recognizing the bump forming surface of the electronic component before mounting the electronic component on the substrate. After the recognition, the electronic component is sent to a flattening step, in which the bump forming surface is pressed against a flat surface to perform flattening to make the height of the bump lower surface uniform, and then the conductive paste is applied. Was.

[0003]

However, in the above-described conventional electronic component mounting method, a recognition error is likely to occur due to a variation in the shape of the bump when the electronic component is recognized. For example, a bump formed of a soft metal such as a solder bump is easily deformed by a load, and when housed in a tray or the like, the load is concentrated on a bump having a high height. May be pressed and deformed. For this reason, at the time of recognition, the state of the bumps varies in shape, such as bumps that normally maintain a spherical shape and bumps that have been partially crushed and have flattened tips.

[0004] Recognition of such bumps causes variations in recognition results in image processing, which causes recognition errors. As described above, the conventional electronic component mounting method for mounting an electronic component with a bump has a problem that it is difficult to recognize the bump formation surface without variation.

Accordingly, an object of the present invention is to provide an electronic component mounting method capable of stably recognizing a bump formation surface.

[0006]

According to a first aspect of the present invention, there is provided an electronic component mounting method for mounting an electronic component on a substrate by bonding a bump formed on the electronic component to an electrode of the substrate. Lowering the suction head holding the electronic component with respect to a flattening stage having a flat surface and pressing the bumps of the electronic component against the flat surface to perform flattening to make the height of the bump lower surface uniform. Moving the suction head holding the electronic component after flattening upward to the recognition means to recognize the electronic component from below, and moving the suction head based on the recognition result to move the electronic component held by the substrate to the substrate. And mounting the device on a substrate.

According to a second aspect of the present invention, there is provided the electronic component mounting method according to the first aspect, including a step of transferring a conductive paste or a flux to the bumps of the recognized electronic component.

According to the present invention, the bump forming surface of the electronic component is recognized after the flattening step of pressing the bumps of the electronic component against the flat surface to adjust the height of the lower surface of the bump, thereby obtaining the bump at the time of recognition. , And stable recognition can be performed.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a perspective view of an electronic component mounting apparatus according to one embodiment of the present invention, FIG. 2 is a plan view of an electronic component mounting apparatus according to one embodiment of the present invention, and FIGS. FIG. 4 is a process explanatory view of the electronic component mounting method of the embodiment.

First, an electronic component mounting apparatus will be described with reference to FIGS. In FIG. 1, a transport path 2 is provided in the center of a base 1 in the X direction. The transport path 2 serves as a positioning unit that transports and positions the substrate 3. Component supply units 4 for supplying electronic components are arranged on both sides of the transport path 2, and a large number of tape feeders 5 are arranged in each component supply unit 4. The tape feeder 5 stores electronic components with bumps held on the tape, and feeds the electronic components to the pickup position 5a by feeding the tape at a pitch.

A transfer head 7 is mounted on the X-axis table 6. The transfer head 7 includes a unit transfer head that can be individually raised and lowered. The X-axis table 6 is supported on both ends by two Y-axis tables 8A and 8B arranged in parallel with each other. X axis table 6 and Y axis table 8
By driving A and 8B, the transfer head 7 moves horizontally. At this time, by attaching a suction nozzle for electronic component suction to each lower end of the unit transfer head,
The transfer head 7 is located at the pickup position 5 of the tape feeder 5.
The electronic component is vacuum-adsorbed and picked up from the substrate a.
Transfer to the top.

A nozzle holding unit 9, a flattening stage 10, a recognition unit 11, and a paste supply unit 12 are arranged on the movement path of the transfer head between the transport path 2 and the component supply unit 4. The nozzle holding unit 9 stocks a large number of suction nozzles mounted on the transfer head 7 and used for suction holding of electronic components and transfer nozzles used for paste transfer. By causing the transfer head 7 to access the nozzle holding unit 9, the nozzle mounted on each unit transfer head can be replaced.

The flattening stage 10 is a pressing stage having a flat surface for pressing on the upper surface, and a transfer head holding an electronic component 13 with bumps 13a formed on the lower surface (see FIG. 3). 7 is lowered with respect to the flattening stage 10 and pressed with a predetermined pressure, thereby flattening the lower end portions of the bumps 13a of the electronic component 13 to perform a flattening process for equalizing the height.

The recognizing unit 11 includes a line camera 11a. When the transfer head 7 picking up the electronic component 13 from the component supply unit 4 passes above, the line camera 1a
Electronic component 13 held by suction nozzle 1a
Is imaged from below. Then, the electronic component 13 is identified and its position is detected by recognizing the imaging result. The paste supply unit 12 stores flux used for soldering the electronic component 13, paste for bonding the electronic component, and the like in a rotary table-shaped container, and supplies the paste with a paste film having a predetermined film pressure. By lowering the electronic component 13 held by the transfer head 7 on the paste coating, the paste is applied to the lower end of the bump 13a.

This electronic component mounting apparatus is configured as described above, and the mounting operation will be described below. First, the transfer head 7 moves to the component supply unit 4, where the unit transfer head performs an elevating operation to pick up the electronic component 13 from the pickup position 5a of the tape feeder 5 by the suction nozzle 7a. Next, the transfer head 7 moves onto the flattening stage 10.

Here, as shown in FIG. 3A, when the unit transfer head is lowered, the bump 13a of the electronic component 13 held by the suction nozzle 7a is pressed against the flat surface 10a of the flattening stage 10. You. This allows
The lower end of the bump 13a is partially crushed, and the unit transfer head is lifted, thereby completing the flattening of the lower end of the bump 13a to flatten and align the height as shown in FIG. 3B. I do.

Next, the transfer head 7 holding the flattened electronic component 13 moves above the recognition unit 11 and is irradiated with illumination light from below as shown in FIG. 3C (arrow a). The electronic component 1 held by the transfer head 7 moving horizontally above the line camera 11a.
The image of the bump forming surface of No. 3 is taken. Then, by performing image processing on the imaging result, it is possible to obtain an image in which the brightness difference between the flat surface of the bump 13a (the non-hatched portion in the bump 13a) and the surroundings is clear as shown in FIG. it can. Then, based on this image, the electronic component 13 is identified and the electronic component 1 is removed from the detected bump 13a.
The position of No. 3 is detected.

In the recognition of the bump formation surface, since the lower end portion of all the bumps 13a is flattened by flattening, the detection of the bumps 13a on the acquired image can be performed stably and with high accuracy. . That is, since the shape of the bump 13a is generally spherical, depending on the irradiation angle and irradiation intensity of the illumination light, the lower line camera 11
The intensity of the light received by a tends to vary. In image recognition, processing is performed based on the luminance on the screen that depends on the received light intensity. Therefore, when an image of a spherical detection target such as the bump 13a is taken, a conventional method is used in which the angle is nearly horizontal. It is necessary to use a dedicated illumination method such as irradiating the bump 13a with illumination light from all directions.

On the other hand, in the recognition of the bump formation surface in the mounting operation shown in the present embodiment, since the lower ends of all the bumps 13a are flattened prior to imaging, the detection target is a grid. These are dotted flat parts. Therefore, these flat portions can be easily recognized by a normal illumination method of irradiating illumination light from below.

In the case of a bump 13a made of a metal which is easily oxidized such as a solder bump, the surface of the bump 13a is covered with an oxide film, so that the surface tends to have a surface property which makes image recognition difficult. Even when the bump 13a in such a state is targeted, the surface of the bump 13a is pressed by the flattening stage 10 by performing flattening prior to imaging, so that the oxide film on the surface is destroyed. The flattened bump surface becomes a metallic glossy surface. Thus, an image suitable for clear recognition can be obtained.

Next, the transfer head 7 moves above the paste supply unit 12. Then, by lowering the unit transfer head, the electronic component 1 held as shown in FIG.
The third bump 13 a is the paste 14 of the paste supply unit 12.
In contact with the coating film. By raising the transfer head 7, the paste 14 is applied by transfer to the lower end of the bump 13a as shown in FIG. 4B.

Thereafter, the transfer head 7 moves onto the substrate 3, where the unit transfer head is lowered with respect to each mounting point, so that the bumps 13 a of the held electronic components 13 are placed on the electrodes of the substrate 3. Then, the electronic component 13 is mounted. In this mounting operation, the displacement of the electronic component 13 with respect to the substrate 3 is corrected based on the position detection result of the recognition unit 11. Thereby, the bumps 13a are joined to the electrodes of the substrate 3, and the mounting of the electronic component 13 is completed.

As described above, in the mounting operation of the electronic component according to the present embodiment, flattening for flattening the bump of the electronic component is performed prior to image recognition of the bump forming surface. . Thus, it is possible to perform stable image recognition while eliminating variations in the state of the bumps at the time of recognition.

[0024]

According to the present invention, the bump formation surface of the electronic component is recognized after the flattening step in which the bumps of the electronic component are pressed against the flat surface to make the height of the bump lower surface uniform. Stable recognition can be performed by eliminating variations in the state of bumps during recognition.

[Brief description of the drawings]

FIG. 1 is a perspective view of an electronic component mounting apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of the electronic component mounting apparatus according to the embodiment of the present invention;

FIG. 3 is a process explanatory view of the electronic component mounting method according to one embodiment of the present invention;

FIG. 4 is a process explanatory view of the electronic component mounting method according to one embodiment of the present invention;

[Explanation of symbols]

 3 Substrate 7 Transfer Head 7a Suction Nozzle 10 Flattening Stage 10a Flat Surface 11 Recognition Unit 12 Paste Supply Unit 13 Electronic Component 13a Bump 14 Paste

Claims (2)

[Claims] An electronic component mounting method for mounting an electronic component on a substrate by bonding a bump formed on the electronic component to an electrode on the substrate, wherein the suction head holding the electronic component has a flat surface. Recognizing a suctioning head that holds the electronic component after the flattening process, by lowering the electronic component bump against the flat surface by lowering the electronic component bump against the flat surface, thereby aligning the height of the bump lower surface. Electronic component mounting, comprising the steps of: moving the electronic component upward from the means and recognizing the electronic component from below; and mounting the electronic component held by moving the suction head based on the recognition result. Method. 2. The electronic component mounting method according to claim 1, further comprising a step of transferring a conductive paste or a flux to the bumps of the electronic component after the recognition.