JP3590196B2 - Pellet bonding method and apparatus - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pellet bonding method and apparatus for bonding a pellet adsorbed to a pellet suction nozzle to a substrate such as a lead frame via a paste by a vertical movement of a bonding arm.
[0002]
[Prior art]
As one of the manufacturing steps of a semiconductor device, there is a pellet bonding step of bonding a semiconductor pellet to a predetermined position on a substrate such as a lead frame. In the bonding apparatus used in this step, a pellet suction nozzle is attached to one end of the bonding arm, and the bonding arm is moved down (including swinging) to press the pellet sucked by the pellet suction nozzle toward the substrate. Then, they are fixed using a paste (adhesive) interposed therebetween, that is, bonded.
[0003]
However, in the prior art disclosed in Japanese Patent Application Laid-Open No. 63-261722, if the pressing force (bonding load) applied to the pellet by the downward movement of the bonding arm is small, bonding failure occurs. From the viewpoint that there is a risk of causing chipping or chipping, the bonding quality is lowered by stopping the lowering movement of the bonding arm when a certain bonding load is reached in the lowering process of the bonding arm and maintaining this state for a certain time. Is to be kept constant.
[0004]
[Problems to be solved by the invention]
However, the prior art using the bonding load and time management has the following problems (1) and (2).
{Circle around (1)} The viscosity of the paste changes depending on temperature conditions and the like. For this reason, even when the same bonding load is applied to the pellets for a certain period of time, the amount of crushing of the paste changes due to the progress of bonding and the like, and the paste thickness varies.
[0005]
{Circle around (2)} The paste is interposed between the substrate and the pellet, and serves as a current path between them. At this time, if the thickness of the paste varies due to the above (1), the electric resistance of the paste varies depending on the thickness, and the electric characteristics vary.
[0006]
An object of the present invention is to provide a method and an apparatus for pellet bonding in which the paste thickness at the time of bonding is made constant and electrical characteristics are made uniform.
[0007]
[Means for Solving the Problems]
The present invention of claim 1, compared bonding arm pellet suction nozzle by a spring which Ru giving resilient movement behavior to the bonding direction of the pellet, and the abutment capable of holding the pellets suction nozzle the bonding arm of the stopper, Bae In the process of lowering the bonding arm at the time of bonding, in which the pellet adsorbed by the let suction nozzle is bonded to the substrate via the paste, the lower surface of the pellet adsorbed by the pellet suction nozzle contacts the substrate via the paste, and then the bonding arm Is further lowered, and stopped at a predetermined lowermost position, the spring is pressed and contracted by a pellet suction nozzle that moves relatively to the bonding arm, and the pellet suction nozzle is separated from the stopper. Below The paste is crushed, and the time when the distance between the substrate and the lower surface of the pellet to which the pellet suction nozzle is suctioned reaches the predetermined paste thickness is defined as the timing for stopping the lowering of the pellet suction nozzle. A pellet bonding method in which the application of the bonding force is stopped at this time, wherein during teaching, the lower surface of the pellet adsorbed by the pellet adsorption nozzle is in contact with the substrate without passing through the paste. The descending distance and the relative position length of the pellet suction nozzle with respect to the bonding arm are detected in advance, and during bonding, the descending distance of the bonding arm and the relative position length of the pellet suction nozzle are detected, and during the teaching. At the time of the bonding Was detected, said time interval between the lower surface and the substrate of pellets The pellets suction nozzle with a descending stroke and relative position the length of the pellet suction nozzle of the bonding arm is adsorbed reaches a thickness predetermined paste This is obtained as a descent stop timing , and the application of the bonding force is stopped at the obtained descent stop timing .
[0008]
The present invention described in claim 2, compared bonding arm pellet suction nozzle by a spring which Ru giving resilient movement behavior to the bonding direction of the pellet, and the abutment capable of holding the pellets suction nozzle the bonding arm of the stopper, Bae In the process of lowering the bonding arm at the time of bonding, in which the pellet adsorbed by the let suction nozzle is bonded to the substrate via the paste, the lower surface of the pellet adsorbed by the pellet suction nozzle contacts the substrate via the paste, and then the bonding arm Is further lowered, and stopped at a predetermined lowermost position, the spring is pressed and contracted by a pellet suction nozzle that moves relatively to the bonding arm, and the pellet suction nozzle is separated from the stopper. Below The paste is crushed, and the time when the distance between the substrate and the lower surface of the pellet to which the pellet suction nozzle is suctioned reaches the predetermined paste thickness is defined as the timing for stopping the lowering of the pellet suction nozzle. Is started, and the application of the bonding force is stopped at this time. In the bonding method , the lowering distance from the movement origin of the bonding arm and the relative position length of the pellet suction nozzle with respect to the bonding arm are detected during bonding. The lowering distance of the bonding arm in the teaching state where the lower surface of the pellet adsorbed by the pellet suction nozzle is in contact with the substrate without the interposition of paste is a ₁ , the relative position length of the pellet suction nozzle is b ₁ , and the predetermined paste thickness is c, the pellet suction nozzle sucks Pellets is lowered a distance a ₂ of the bonding arm, which is detected by the bonding state of being bonded to the substrate through the paste, the relative positions length b ₂ of the pellet suction nozzle,
c = (a ₁ + b ₁ ) − (a ₂ + b ₂ )
Is determined as the descent stop timing , and the application of the bonding force is stopped at the determined descent stop timing .
[0009]
According to a third aspect of the present invention, in the first or second aspect of the present invention, the stopping of the application of the bonding force is performed by raising the bonding arm or lowering the substrate. is there.
[0011]
According to a fourth aspect of the present invention , a pellet suction nozzle can be held against a stopper of a bonding arm by a spring which gives the pellet suction nozzle an elastic movement in the bonding direction of the pellet to the bonding arm. In the process of lowering the bonding arm at the time of bonding, in which the pellet adsorbed by the nozzle is bonded to the substrate via the paste, the lower surface of the pellet adsorbed by the pellet suction nozzle contacts the substrate via the paste, and then the bonding arm is further moved. It is lowered and stopped at a predetermined lowermost position, and the spring is pressed and contracted by the pellet suction nozzle moving relatively to the bonding arm to separate the pellet suction nozzle from the stopper, and the pellet suction nozzle is lowered by the spring force. The paste is crushed, and the time when the distance between the substrate and the lower surface of the pellet to which the pellet suction nozzle is suctioned reaches the predetermined paste thickness is defined as the timing for stopping the lowering of the pellet suction nozzle. was initiated, a pellet bonding apparatus stops the application of the bonding force at this time, and the vertical drive unit for vertically moving the bonding arm to the substrate, and the control unit of the vertical drive unit, the movement origin of the bonding arm An arm position detector for detecting a descending distance of the nozzle, and a nozzle position detector for detecting a relative position length of the pellet suction nozzle with respect to the bonding arm. The control unit includes an arm position detector and a nozzle position detector. The result of the detection is obtained, and the lower surface of the pellet adsorbed by the pellet adsorption nozzle is A ₁ a descending stroke of the bonding arm of the teaching state in contact with the substrate without via, b ₁ the relative positions length of the pellet suction nozzle when a predetermined paste thickness to be is c, pellets pellet suction nozzle is adsorbed paste The lowering distance a _{2 of} the bonding arm and the relative position length b _{2 of} the pellet suction nozzle, which are detected in the bonding state of bonding to the substrate via
c = (a ₁ + b ₁ ) − (a ₂ + b ₂ )
Determined as the descending stop timing when to satisfy at lowering stop timing determined is obtained as Ru increases the bonding arm.
[0012]
According to the first and third aspects of the present invention, the following operation (a) is provided.
(a) At the time of bonding, the application of the bonding force is stopped when the distance between the lower surface of the pellet and the substrate, which is adsorbed by the pellet adsorption nozzle, reaches a predetermined paste thickness. It can be constant. Therefore, even if the viscosity of the paste changes due to temperature conditions or the like, bonding is performed while repeatedly maintaining a predetermined paste thickness, and uniform electrical characteristics can be achieved.
[0013]
According to the present invention described in claims 2, 3, and 4 , there is the following operation (b) .
(b) The timing for stopping the lowering of the pellet suction nozzle is determined by a predetermined distance a ₁ , a ₂ from the origin of movement of the bonding arm, and a relative position length b ₁ , b _{2 of} the pellet suction nozzle with respect to the bonding arm. The lowering timing of the pellet suction nozzle at which the paste thickness becomes constant can be accurately controlled.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic diagram showing an example of a bonding apparatus, FIG. 2 is a schematic diagram showing a bonding arm and a pellet suction nozzle, and FIG. 3 is a block diagram showing a control system of the present invention.
[0015]
In FIG. 1, 1 is a pellet, 2 is a lead frame (substrate), and 3 is a paste. In the pellet bonding apparatus 10, 11 is an XY table, 12 is a machine stand erected on the XY table 11, 13 is a screw shaft rotatably supported by the machine 12 and whose axis is in the vertical direction, and 14 is A servomotor (up and down drive unit) supported on the machine base 12 and rotationally driving the screw shaft 13, 15 is a guide shaft fixedly supported on the machine base 12 in parallel with the screw shaft 13, and 16 is a guide shaft 15 for the machine base 12. A bush 17 is provided on a sliding portion, and a female screw 18 is provided at a position corresponding to the screw shaft 13, and the female screw 18 and the screw shaft 13 are screwed together. Reference numeral 19 denotes a support shaft that is vertically attached to the elevating plate 16, 21 denotes a bonding arm having one end fixed to the support shaft 19 and extends in the horizontal direction, and 22 denotes a bonding shaft 23 provided at the other end of the bonding arm 21. 2 shows a pellet suction nozzle held slidably. Reference numeral 24 denotes a spring interposed between the bonding arm 21 and the pellet suction nozzle 22. The bonding arm 21 provides the pellet suction nozzle 22 with elastic movement in the bonding direction of the pellet 1 due to the presence of the spring 24. Support. When the bonding arm 21 is on the movement origin z side, the pellet suction nozzle 22 is held by the spring 24 against the stopper 21A of the bonding arm 21. The pellet suction nozzle 22 is connected to a suction device via an electromagnetic valve or the like (not shown).
[0016]
Next, in FIG. 3, reference numeral 31 denotes a control device (control unit), 32 denotes an XY drive unit of the XY table 11, and 33 denotes a vertical drive unit of the servomotor 14. That is, the control device 31 controls the XY table 11 and the servo motor 14 to perform the following bonding operation.
[0017]
(1) A drive signal is sent from the control device 31 to the XY drive unit 32 with the bonding arm 21 positioned at the raised position, the XY table 11 moves, and the pellet suction nozzle 22 is positioned at the pellet supply position A. Next, the servo motor 14 is rotated forward and the bonding arm 21 is lowered. Then, the pellet suction nozzle 22 sucks the pellet 1.
[0018]
(2) The bonding arm 21 is lifted while the pellet 1 is sucked by the pellet suction nozzle 22. Next, the movement of the XY table 11 is controlled, and the pellet 1 sucked by the pellet suction nozzle 22 is positioned at the bonding position B in the lead frame 2. Then, the bonding arm 21 is lowered from the movement origin z by the servomotor 14, and the pellet 1 and the lead frame 2 are bonded via the paste 3. At the time of bonding, the bonding arm 21 descends to a position sufficient for the pellet suction nozzle 22 to move against the movement behavior of the spring 24 and stops. When the pellet suction nozzle 22 reaches the descent stop timing to be described later, the bonding arm 21 is raised and positioned at the movement origin z, and one cycle of the bonding operation is completed.
[0019]
However, in the bonding operation (2) of the above-described bonding operation, the control device 31 moves the lower surface of the pellet 1 that is being sucked by the pellet suction nozzle 22 through the paste 3 while the bonding arm 21 is being lowered. After the contact with the second arm 2, the bonding arm 21 is further lowered and stopped at a predetermined lowest position. As a result, the pellet suction nozzle 22 moves relative to the bonding arm 21 and separates from the stopper 21A with the spring 24 pressed and contracted. Then, the pellet suction nozzle 22 continues to descend while crushing the paste 3 by the spring force. The control device 31 calculates a point in time at which the gap g between the lower surface of the pellet 1 on which the pellet adsorption nozzle 22 is adsorbed and the lead frame 2 reaches a predetermined paste thickness c as a descent stop timing of the pellet adsorption nozzle 22, The raising and lowering of the bonding arm 21 is started with respect to the vertical drive unit 33 of the servomotor 14, and at this time, the application of the bonding force is stopped.
[0020]
The control device 31 includes an arm position detector 41 and a nozzle position detector 42 for calculating the timing at which the pellet suction nozzle 22 stops descending. The arm position detector 41 is composed of, for example, an encoder that detects the amount of rotation of the screw shaft 13 and detects a descending distance of the bonding arm 21 from the movement origin z. The nozzle position detector 42 includes, for example, a gap sensor provided on the bonding arm 21 to detect a gap with the pellet suction nozzle 22, and detects a relative position length of the pellet suction nozzle 22 with respect to the bonding arm 21.
[0021]
Thereby, the control device 31 obtains the detection results of the arm position detector 41 and the nozzle position detector 42, and teaches that the lower surface of the pellet 1 adsorbed by the pellet adsorption nozzle 22 is in contact with the lead frame 2 without passing through the paste 3. When the lowering distance of the bonding arm 21 in the state (FIG. 2A) is a ₁ , the relative position length of the pellet suction nozzle 22 is b ₁ , and the predetermined paste thickness is c, the pellet suction nozzle 22 is suctioned. The descent distance a ₂ of the bonding arm 21 and the relative position length b _{2 of the} pellet suction nozzle 22 detected in the bonding state (FIG. 2B) in which the pellet 1 is bonded to the lead frame 2 via the paste 3 are as follows:
c = (a ₁ + b ₁ ) − (a ₂ + b ₂ )
Is satisfied is defined as the above-described descent stop timing of the suction nozzle 22.
[0022]
Therefore, in the bonding apparatus 10, when the pellet 1 adsorbed by the pellet suction nozzle 22 supported by the bonding arm 21 is bonded to the lead frame 2 via the paste 3, the descent stop timing of the pellet suction nozzle 22 is set as described above. According to the present embodiment determined as described above, there are the following operations (1) and (2).
[0023]
{Circle around (1)} At the time of bonding, a point in time when the interval between the lower surface of the pellet 1 on which the pellet suction nozzle 22 is sucking and the lead frame 2 has reached a predetermined paste thickness c is defined as a timing for stopping the lowering of the pellet suction nozzle 22. In this case, the application of the bonding force is stopped, so that the paste thickness at the time of bonding can be made constant. Therefore, even if the viscosity of the paste 3 changes due to temperature conditions or the like, bonding is performed while maintaining a predetermined paste thickness, and electrical characteristics can be made uniform.
[0024]
{Circle around (2)} The descent stop timing of the pellet suction nozzle 22 is detected by the arm position detector 41, the descent distances a ₁ and a ₂ from the movement origin of the bonding arm 21, and the pellet suction nozzle 22 detected by the nozzle position detector 42. Is calculated from the relative position lengths b ₁ and b ₂ with respect to the bonding arm 21 and a predetermined paste thickness c, and accurately controls the timing of stopping the descent of the pellet suction nozzle 22 at which the paste thickness becomes constant. it can.
[0025]
As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to the embodiments, and a design change or the like may be made without departing from the gist of the present invention. The present invention is also included in the present invention. For example, the vertical drive unit of the bonding arm is not limited to a servomotor, but may be a linear drive device. The vertical drive mechanism of the bonding arm is not limited to a mechanism using a screw shaft, but may be a rotary cam that is stopped immediately by a stop signal from the control unit.
[0027]
Further, in the above embodiment, the application of the bonding force is stopped by starting the raising of the bonding arm at the timing of stopping the lowering of the pellet suction nozzle, but instead, the lead frame 2 is lowered at the same timing. You may do it.
[0028]
Also, the required paste thickness c can be obtained by arbitrarily setting the descent distances a ₁ and a ₂ from the origin of movement of the bonding arm and the relative position lengths b ₁ and b ₂ of the pellet suction nozzle with respect to the bonding arm. Can be.
[0029]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain a pellet bonding method and an apparatus that make the paste thickness at the time of bonding constant and uniform electric characteristics.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an example of a bonding apparatus.
FIG. 2 is a schematic diagram showing a bonding arm and a pellet suction nozzle.
FIG. 3 is a block diagram showing a control system of the present invention.
[Explanation of symbols]
1 pellet 2 lead frame (substrate)
3 Paste 10 Bonding device 21 Bonding arm 22 Pellet suction nozzle 31 Control device (control unit)
41 Arm position detector 42 Nozzle position detector

Claims (4)

The spring to bonding arm Ru giving resilient movement behavior pellet suction nozzle to the bonding direction of the pellet, and the abutment capable of holding the pellets suction nozzle the bonding arm of the stopper,
The pellet was sucked to the suction nozzle pellets falling course of the bonding arm at the time of bonding to bond to the substrate through the paste, after the lower surface of the pellet the pellet suction nozzle is adsorbed is in contact with the substrate through the paste, bonding The arm is further lowered and stopped at a predetermined lowermost position, and the spring is pressed and contracted by the pellet suction nozzle which moves relative to the bonding arm, and the pellet suction nozzle is separated from the stopper, and the pellet force is attracted by the spring force. The nozzle is lowered and the paste is crushed, and when the interval between the lower surface of the pellet and the substrate to which the pellet suction nozzle is adsorbed reaches a predetermined paste thickness, the lowering timing of the pellet adsorber nozzle is set as the stop timing, and bonding is performed at this lowering stop timing. arm Rise was started, a pellet bonding method to stop the application of the bonding force at this point,
At the time of teaching, the descending distance of the bonding arm and the relative position length of the pellet suction nozzle with respect to the bonding arm are detected in a state where the lower surface of the pellet sucked by the pellet suction nozzle is in contact with the substrate without passing through the paste. ,
At the time of bonding, the descending distance of the bonding arm and the relative position length of the pellet suction nozzle are detected,
The distance between the substrate and the lower surface of the pellet suctioned by the pellet suction nozzle is determined by using the descending distance of the bonding arm and the relative position length of the pellet suction nozzle detected at the time of the teaching and at the time of the bonding, respectively. seek time of reaching of the paste thickness as the descending stop timing, Lupe to stop the application of the bonding force lowered stop timing determined cmdlet bonding method. The spring to bonding arm Ru giving resilient movement behavior pellet suction nozzle to the bonding direction of the pellet, and the abutment capable of holding the pellets suction nozzle the bonding arm of the stopper,
The pellet was sucked to the suction nozzle pellets falling course of the bonding arm at the time of bonding to bond to the substrate through the paste, after the lower surface of the pellet the pellet suction nozzle is adsorbed is in contact with the substrate through the paste, bonding The arm is further lowered and stopped at a predetermined lowermost position, and the spring is pressed and contracted by the pellet suction nozzle which moves relative to the bonding arm, and the pellet suction nozzle is separated from the stopper, and the pellet force is attracted by the spring force. The nozzle is lowered and the paste is crushed, and when the interval between the lower surface of the pellet and the substrate to which the pellet suction nozzle is adsorbed reaches a predetermined paste thickness, the lowering timing of the pellet adsorber nozzle is set as the stop timing, and bonding is performed at this lowering stop timing. arm Rise was started, a pellet bonding method to stop the application of the bonding force at this point,
At the time of bonding, a descending distance from the movement origin of the bonding arm and a relative position length of the pellet suction nozzle with respect to the bonding arm are detected,
The lowering distance of the bonding arm in the teaching state in which the lower surface of the pellet adsorbed by the pellet suction nozzle is in contact with the substrate without passing through the paste is a ₁ , the relative position length of the pellet suction nozzle is b ₁ , and the predetermined paste thickness is c. and when,
The descent distance a _{2 of} the bonding arm, which is detected in a bonding state in which the pellet adsorbed by the pellet suction nozzle is bonded to the substrate via the paste, and the relative position length b _{2 of} the pellet suction nozzle,
c = (a ₁ + b ₁ ) − (a ₂ + b ₂ )
Is determined as the descent stop timing , and the application of the bonding force is stopped at the determined descent stop timing . 3. The pellet bonding method according to claim 1, wherein the application of the bonding force is stopped by raising the bonding arm or lowering the substrate. The pellet suction nozzle can be held against the stopper of the bonding arm by a spring that gives the pellet suction nozzle elastic movement in the pellet bonding direction to the bonding arm.
In the process of lowering the bonding arm during bonding, in which the pellet adsorbed by the pellet suction nozzle is bonded to the substrate via the paste, the lower surface of the pellet adsorbed by the pellet suction nozzle contacts the substrate via the paste, and then the bonding arm Is further lowered, and stopped at a predetermined lowermost position, the spring is pressed and contracted by a pellet suction nozzle that moves relatively to the bonding arm, and the pellet suction nozzle is separated from the stopper. Is lowered, the paste is crushed, and the point at which the interval between the substrate and the lower surface of the pellet on which the pellet suction nozzle is suctioned reaches a predetermined paste thickness is defined as the timing for stopping the lowering of the pellet suction nozzle. Rise was started, a pellet bonding apparatus stops the application of the bonding force at this point,
An up-down drive unit that moves the bonding arm up and down with respect to the substrate;
A control unit for the vertical drive unit ,
An arm position detector for detecting a descending distance from a movement origin of the bonding arm,
Having a nozzle position detector for detecting the relative position length of the pellet suction nozzle with respect to the bonding arm,
The control unit obtains the detection results of the arm position detector and the nozzle position detector, and determines the descending distance of the bonding arm in the teaching state in which the lower surface of the pellet adsorbed by the pellet adsorption nozzle contacts the substrate without passing through the paste. ₁ , when the relative position length of the pellet suction nozzle is b ₁ and the predetermined paste thickness is c, the bonding arm of the bonding arm detected in the bonding state where the pellet sucked by the pellet suction nozzle is bonded to the substrate via the paste. The descending distance a ₂ and the relative position length b _{2 of} the pellet suction nozzle are:
c = (a ₁ + b ₁ ) − (a ₂ + b ₂ )
Determined as the descending stop timing when to satisfy, Ru increases the bonding arm at lowering stop timing determined pellets bonding apparatus.

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