JPH10135250A - Bonding unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the bonding pressure adjustable accurately over a wide range, without needing of parts change, by canceling the self wt. of a bonding head by three magnets disposed so as to mutually repel, and using them for constituting a pressure source for the bonding pressure. SOLUTION: The bonding unit comprises a bonding head 31 for attracting a semiconductor pellet A, an arm 40 fixed to the head 31, a first magnet 44 horizontally mounted on the arm 40, a second magnet 45 mounted in a head holder 32 with their same poles opposed above the first magnet 44, and third magnet 50 mounted in the head holder 32 with the same poles opposed below the first magnet 44. The repulsion between the first and the third magnets 44, 50 cancels the self wt. of the bonding head 31 and the force between the first and the second magnets 44, 45 is a pressure source for the bonding pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding unit for bonding a semiconductor pellet (chip) picked up to a substrate or a heat sink at a predetermined pressure in a die bonder.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. Hei.
The thing described in 291493 is known. The bonding unit includes a frame that is moved up and down by an elevating mechanism, and a bonding head that is slidably held in a vertical direction on a holder of the frame. And a balance spring. The balance spring urges the bonding head upward to offset the weight of the bonding head so that the bonding head does not affect the weight of the bonding head. Further, the pressing spring lowers the bonding head through the frame and starts to expand from the time when the sucked pellet hits the heat sink or the like, and urges the bonding head downward. The urging by the pressure spring acts on the pellet as a bonding pressure (load), and the pellet is bonded to the heat sink with an appropriate pressure.

[0003] Therefore, the bonding pressure is determined by the lowering stroke of the frame from when the pellet abuts the heat sink until it stops, and the spring constant of the pressure spring. In this case, the bonding pressure varies depending on the type of solder or adhesive interposed between the pellet and the heat sink, and on the contact area of the pellet, and its range from a high to a low is considerably wide. For this reason, it is necessary to prepare a plurality of pressure springs having different spring constants and replace them as appropriate. However, in the bonding unit described in the above publication, one end of the pressure spring is expanded and contracted by a motor, The bonding pressure can be adjusted over a wide range without replacing the spring.

[0004]

As described above, in the conventional bonding unit, the bonding pressure can be adjusted over a wide range by a single pressure spring. However, the structure becomes complicated and the premise is that the pressure spring However, there is a problem that the spring unit needs to have a very long spring stroke, and the bonding unit becomes large. Of course, if a pressure spring having a short spring stroke is used, the size of the bonding unit can be reduced. However, in such a case, the pressure spring needs to be replaced, and the handling becomes complicated. Further, the influence of the self-weight of the bonding head can be eliminated, but the influence of the self-weight of the pressure spring cannot be eliminated.

An object of the present invention is to provide a bonding unit having a very simple structure and capable of adjusting a bonding pressure in a wide range and with high accuracy without requiring replacement of parts.

[0006]

According to the present invention, there is provided a bonding unit comprising: a head holder which is raised and lowered by lifting means; a bonding head which is slidably supported by the head holder in a vertical direction; and an arm which is fixed to the bonding head.
A first magnet mounted horizontally on the arm, a second magnet mounted on the head holder and arranged above the first magnet with the same poles facing each other, and a second magnet mounted on the head holder and mounted below the first magnet; A third magnet in which the poles are arranged to face each other.

According to this configuration, the first magnet and the third magnet
Since the repulsive force generated between the magnet and the magnet acts in a direction in which the bonding head is lifted up via the arm, the weight of the bonding head slidably supported by the head holder is balanced with the repulsive force. For this reason,
At the time of bonding, the influence (including inertia and the like) of the weight of the bonding head can be eliminated. On the other hand, when the pellets adsorbed on the bonding head strike the object to be bonded in the process of lowering the bonding head together with the head holder by the elevating means, only the head holder is lowered leaving the bonding head, and eventually stops. Then, the second magnet on the moving side sufficiently approaches the first magnet on the stationary side, and a certain repulsive force is generated therebetween. The repulsive force urges the bonding head downward from the first magnet via the arm, and acts on the pellet as a bonding pressure (load). In this case, the bonding pressure is determined by the magnetic flux densities of the first and second magnets and the separation distance between the two magnets. Since the magnetic flux density of both magnets is constant, if both magnets with sufficient magnetic force are installed compared to the maximum bonding pressure required by the device, the separation distance between both magnets,
That is, the bonding pressure is determined by the downward stroke of the head holder. Therefore, if the relationship between the descending stroke and the repulsive force of both magnets (which is always constant) is measured in advance, it is possible to adjust the bonding pressure arbitrarily from zero to the required maximum pressure. Also, unlike the conventional spring, the magnet is not disposed across the members (between the head holder and the bonding head), so that the influence of the weight of the spring itself can be eliminated.

In this case, it is preferable to further include a pressure sensor for detecting a repulsive force received by the second magnet from the first magnet.

According to this configuration, an alarm can be issued using the pressure sensor as described later.
It is possible to detect whether the bonding pressure is zero, rise from zero, and whether or not a predetermined bonding pressure is applied. By using the rise from zero, the descending stroke of the head holder after the application of the bonding pressure can be controlled, and the bonding pressure can be accurately applied even if the thickness of the object to be bonded and the object to be bonded vary. Can be. Of course, if this detection result is fed back to the lowering operation of the head holder, the accuracy of the bonding pressure can be improved.
Can be more enhanced. In addition, it is possible to detect a defective supply of solder, a bite of dust, and the like.

In this case, an alarm is connected to the pressure sensor, and the alarm preferably issues an alarm when the detected value of the pressure sensor exceeds a predetermined pressure value.

In order to perform proper bonding, the bonding pressure needs to be a predetermined value (range). If the bonding pressure exceeds this value, a defect occurs on either the device side or the object to be bonded. That is what is happening.
Therefore, by issuing an alarm in such a case, it is possible to prevent inappropriate bonding from continuing. Of course, the driving of the apparatus may be stopped simultaneously with this alarm.

[0012] In these cases, it is preferable to further include control means for controlling the lower end position of the head holder via the elevating means based on the detection result of the pressure sensor.

According to this configuration, when the pressure sensor reaches a desired set pressure, the lowering of the head holder is stopped via the elevating means. Thus, a desired bonding pressure can be applied to the bonding target regardless of the descending stroke of the head holder. Therefore,
Even if the bonding object and the object to be bonded vary in thickness, a desired bonding pressure can be applied with high accuracy, and bonding can be performed accurately and stably.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an electronic component mounting apparatus having a bonding unit according to an embodiment of the present invention; FIG. 1 is a front view of the electronic component mounting device. As shown in FIG. 1, the electronic component mounting device 1 includes a heat sink supply device 2, a bonding device 3, and a mounting device 4. The heat sink supply device 2 is a so-called parts feeder,
The heat sink to be bonded is sent to the bonding apparatus 3 in a state of being aligned in a line. The bonding device 3 bonds semiconductor pellets (chips) supplied from the outside to the heat sink supplied from the heat sink supply device 2 via solder, and sends the semiconductor pellets (chips) to the mounting device 4. The mounting device 4 mounts the semiconductor pellet bonded to the heat sink on a substrate.

As shown in the front view of FIG. 1 and the side view of FIG. 2, the bonding device 3 includes a transfer passage 6 for a heat sink extending substantially horizontally from the heat sink supply device 2 to the mounting device 4 in the cabinet 5. And two sets of die bonders 3 so as to face the transport passage 6.
a, 3a. The heat sink is intermittently fed in units of two, and one die is attached to each die bonder 3a, 3a.
The pieces are supplied almost simultaneously. In addition, the code | symbol 7 in a figure is
These are feed claws for intermittently feeding the heat sink.

Each die bonder 3a comprises a solder supply unit 11, a die supply unit 12, a pre-alignment unit 13, and a bonding unit 14. The solder supply unit 11 is of a dispenser type using a syringe, and applies solder to the upper surface of the heat sink heated by the transport passage 6 incorporating a heater.

The die supply unit 12 includes an upper pickup mechanism 15, a lower push-up mechanism 16 facing the pickup mechanism 15, and an XY table 17 provided between the pickup mechanism 15 and the push-up mechanism 16. Have. The semiconductor pellet which is a die may be supplied in a state where the semiconductor wafer is diced, or may be supplied in a state where each semiconductor pellet is separated after dicing. In the former, the semiconductor pellets are mounted on a dedicated carrier while being adhered to the wafer adhesive tape, and are set on the XY table 17. In the latter, the semiconductor pellets are arranged in a lattice and stored in a dedicated tray, and Set it on the table 17. In the case of the latter dedicated tray, XY
The table 17 is driven to pick up the desired semiconductor pellets directly under the pickup mechanism 15 for picking up. In the case of the latter dedicated carrier, the push-up mechanism 16 is driven immediately below the pickup mechanism 15, The semiconductor pellet is pushed up and peeled off from the wafer adhesive tape, and then picked up. Then, the picked-up semiconductor pellets are transported to the pre-alignment unit 13 by the pick-up mechanism 15. Reference numeral 18 in the figure denotes a camera for identifying defective semiconductor pellets on the XY table 17.

The pre-alignment unit 13 has a rotary table 19 and a recognition camera 20 for recognizing the angle of the semiconductor pellet on the rotary table 19. The semiconductor pellets conveyed from the pick-up mechanism 15 are placed on the turntable 19, and the recognition camera 20 takes an image of the semiconductor pellets from above, and the angle of the semiconductor pellets in the horizontal plane is recognized. Then, based on the recognition result, the rotary table 19 rotates minutely, and the angle correction of the semiconductor pellet is performed. The semiconductor pellets whose angles have been corrected are transferred to the bonding unit 14.

The bonding unit 14 adsorbs the semiconductor pellet and bonds the semiconductor pellet to a heat sink. The bonding unit 21 moves the bonding unit 21 in the horizontal direction (Y-axis direction) and moves up and down (Z-axis direction). And a mechanism (elevating means) 22. The elevating mechanism 22 moves the bonding unit 21 between the rotary table 19 of the pre-alignment unit 13 and the transport path 6, and moves the bonding unit 21 facing the rotary table 19 and the transport path 6 up and down. Then, the bonding unit 21 facing the rotary table 19 descends to adsorb the semiconductor pellets on the rotary table 19, and the bonding unit 21 facing the transport path 6 descends and removes the semiconductor pellets from the heat sink on the transport path 6. Bonding.

As shown in FIG. 3, the bonding unit 21 includes a bonding head 31 for sucking the semiconductor pellet A, and a head holder 32 for holding the bonding head 31 slidably in the vertical direction. 32 is fixed to the lower end of the lifting mechanism 22.
The head holder 32 includes a mounting portion 33 fixed to the elevating mechanism 22, and a holding portion 34 extending from the mounting portion 33 and having an “C” -shaped cross-section including an upper holding portion 34 a and a lower holding portion 34 b. . Upper holding part 34a and lower holding part 34b
Guide holes 35, 35 are formed coaxially at the tips of the two, respectively, and the bonding head 31 is held in both the guide holes 35, 35. On the other hand, the bonding head 31 is provided with a collet 36 for adsorbing the semiconductor pellet A.
And a collet holder 37 including a holder body 38 for holding the collet 36 and a shaft 39.

The bonding head 31 has a shaft 39
Are inserted into both the guide holes 35 of the upper holding portion 34a and the lower holding portion 34b, and in this state, a gap between the upper holding portion 34a and the lower holding portion 34b is provided substantially in the middle of the shaft portion 39. The arm 40 is fixed so as to be located at the position.
As a result, the bonding head 31 slides vertically in a range where the arm 40 abuts on the upper holding portion 34a and the lower holding portion 34b. The arm 40 includes a horizontal piece 41 extending toward the inner space of the holding portion 34 and an upper holding portion 34.
and a vertical piece 42 extending upward along the tip end surface of FIG. The vertical piece 42 is sandwiched between a pair of rollers 43 attached to the distal end surface of the upper holding portion 34a, and functions as a rotation stopper for the bonding head 31. Also,
A first magnet 44 slightly thinner than the thickness of the horizontal piece 41 is embedded in the horizontal piece 41.

A second magnet 45 is provided directly above the first magnet 44 so that the same poles as the first magnet 44 face each other. The second magnet 45 is attached so as to be embedded in a magnet arm 46, and the magnet arm 46 is attached at its base to a bracket 47 extending from the upper holding portion 34a so as to be vertically swingable. A pressure sensor 48 composed of a load cell or the like is attached to the bracket 47 above the magnet arm 46. The detection end 48a of the pressure sensor 48 is in contact with the upper side of the second magnet 45 via the magnet arm 46, so that the force (pressure) received by the second magnet 45 can be detected. On the other hand, immediately below the first magnet 44, a third magnet 50 is buried in a seating portion 49 protruding from the lower holding portion 34b so that the first magnet 44 and the same pole face each other. Although each of the magnets 44, 45, and 50 in the embodiment is constituted by a permanent magnet, it may be constituted by an electromagnet.

As described above, the second and third magnets 45 and 50 are arranged so as to oppose the first magnet 44 and to repel each other with the same poles facing each other. The repulsive force generated between the first magnet 44 and the third magnet 50 cancels the self-weight of the bonding head 31, and the repulsive force generated between the first magnet 44 and the second magnet 45 is determined by the bonding pressure ( load)
Pressure source. That is, the first and third magnets 4
The repulsive force between 4, 50 urges the arm 40 upward and slightly lifts the arm 40 from the lower holding portion 34b, and balances with the own weight of the bonding head (+ arm 40) 31. In this state, the first and third magnets 4
4 and 50 and the first and second magnets 44 and 45
The repulsion force is balanced, and the bonding pressure (although the pressure sensor 48 is not a zero value) is zero.

On the other hand, when the bonding unit 21 is moved down by the elevating mechanism 22 and the semiconductor pellet A adsorbed on the bonding head 31 is grounded (contacted) with the heat sink (actually, the solder C) B, the head holder 32 is thereafter moved. Until the lowering of the bonding stops, the bonding head 31 moves up relative to the head holder 32. As a result, the first magnet 44 approaches the second magnet 45, and the repulsive force between them increases. The lower end position of the head holder 32 is preset according to the thickness of the semiconductor pellet A, the thickness of the heat sink B, and the properties of the solder C, and the first and second magnets in a state where the head holder 32 stops at the lower end position. The repulsive force between 44 and 45 is the bonding pressure.

Then, the bonding pressure is supplied to the pressure sensor 48 via the second magnet 45 which slightly swings.
Is detected by In this case, the detection result of the pressure sensor 48 can be fed back to the elevating mechanism 22 to control the bonding pressure. However, in the embodiment, the rising end of the pressure is detected to control the lower end position of the head holder 32. At the same time, an alarm is issued when a predetermined pressure value is exceeded (a controller, an alarm device, and the like are not shown). That is, since the bonding pressure is determined by the descending stroke of the head holder 32 after the semiconductor pellet A attracted to the bonding head 31 is grounded to the solder C, if this grounding is detected at the rise of the pressure of the pressure sensor 48, Even if the thickness of the semiconductor pellet A and the thickness of the heat sink B have manufacturing variations (acceptable range), the bonding pressure can be kept constant. If an alarm is issued when the pressure exceeds a predetermined pressure value, even if dust or the like is caught between the semiconductor pellet A and the heat sink B, this can be recognized.

As described above, according to the bonding unit 21 of the present embodiment, the first and third magnets 4
4, 50, it is possible to eliminate the influence (including inertia and the like) of the bonding head 31 in the bonding of the semiconductor pellet A. In this case, it is particularly effective when the bonding pressure is smaller than the weight of the bonding head 31. In addition, the first and third magnets 44 and 45 can apply an appropriate bonding pressure to the semiconductor pellet A in bonding the semiconductor pellet A. In this case, the bonding pressure is determined by the repulsive force of the first and third magnets 44 and 45, and the repulsive force is determined by the magnetic force of the two magnets 44 and 45 and the separation distance. Therefore, for each of the semiconductor pellet A, the heat sink B, and the solder C, the separation distance and the descending stroke of the head holder 32 (actually,
If the relationship between the semiconductor pellet A adsorbed by the bonding head 31 and the descending stroke after the semiconductor pellet A is grounded to the solder C) is measured, bonding can be performed at a desired bonding pressure. Moreover, the magnet 4 to be used
If the magnetic force of 4, 45 is sufficiently strong, magnets 44, 45
By using the repulsive force of (1), the bonding pressure can be set in a wide range, and a stable bonding pressure can be applied to the semiconductor pellet A.

[0027]

As described above, according to the bonding unit of the present invention, the self-weight of the bonding head is offset by the three magnets arranged so as to repel each other, and a pressure source for the bonding pressure is formed. Because
The bonding pressure can be adjusted over a wide range and with high accuracy without having a very simple structure and requiring component replacement. Therefore, when this is mounted on a bonding apparatus, the handleability and reliability of the apparatus can be improved.

[Brief description of the drawings]

FIG. 1 is a front view of an electronic component mounting apparatus on which a bonding unit according to an embodiment of the present invention is mounted.

FIG. 2 is a side view of a bonding apparatus equipped with a bonding unit according to the embodiment.

FIG. 3 is a side view of the bonding unit according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electronic component mounting device 3 Bonding device 14 Bonding part 21 Bonding unit 22 Elevating mechanism 31 Bonding head 32 Head holder 40 Arm 44 First magnet 45 Second magnet 48 Pressure sensor 50 Third magnet

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Sachi Nishio 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Yoshio Ichikawa 2-chome, Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd.

Claims (4)

[Claims] 1. A head holder which is moved up and down by an elevating means, a bonding head slidably supported by the head holder in a vertical direction, an arm fixed to the bonding head, and a first magnet horizontally mounted on the arm. A second magnet attached to the head holder and arranged above the first magnet with the same poles facing each other; and a second magnet attached to the head holder and facing the same poles below the first magnet. A bonding unit, comprising: a third magnet arranged in a vertical direction. 2. The bonding unit according to claim 1, further comprising a pressure sensor for detecting a repulsive force received by the second magnet from the first magnet. 3. An alarm means is connected to the pressure sensor, and the alarm means issues an alarm when a detected value of the pressure sensor exceeds a predetermined pressure value. 3. The bonding unit according to 2. 4. Based on a detection result of the pressure sensor,
4. The bonding unit according to claim 2, further comprising control means for controlling a lower end position of the head holder via the elevating means.