JP2009277920A - Electronic component packaging method - Google Patents

Abstract

A pressing load continues to be stable even when pressed for a long time, and high mounting quality is ensured.
VCM 3 is pressed by current control, servo motor 6 is position controlled, nozzle 1 is lowered in the mounting position direction, and it is confirmed that electronic component P is in contact with circuit board S. Further, the electronic component P is lowered by a predetermined pushing amount, the VCM 3 is switched from current control to load feedback control, is raised to the initial ultimate load P ₁ at an arbitrary time T ₀ , and the arbitrary time T at which the load P ₁ is stabilized. After the elapse of _1, the pressure is switched to the current control for a predetermined time. Any time T ₁ after which the load P ₁ is stabilized, by switching to the current control without the load feedback control, the influence of the temporal instability of the pressing load can be suppressed drift without being . This load stabilization makes it possible to reduce the incidence of defective bonding.
[Selection] Figure 2

Description

  The present invention relates to an electronic component mounting method for mounting an electronic component on a circuit board.

  As a conventional electronic component mounting method, there is a method of mounting an electronic component while feeding back a load using a load detection means (see, for example, Patent Document 1). Hereinafter, a conventional electronic component mounting method will be described with reference to FIGS. FIG. 12 is a schematic diagram illustrating a component mounting head of the electronic component mounting apparatus described in Patent Document 1, and FIG. 13 is a diagram illustrating a specific example of controlling the operation of the component mounting head.

  In FIG. 12, the component mounting head includes a nozzle 1, a pressure shaft 2, a VCM (voice coil motor) 3, a ball screw 4, a nut 5, a servo motor 6, an encoder 7, and a rotary shaft servo motor 8. A rotary shaft encoder 9, a head unit 10, a heat insulating block 11, bearings 12, 13 and 14, a rotary shaft 15, and a force sensor 16.

  The nozzle 1 holds the electronic component P at its tip by, for example, air pressure (negative pressure). The pressure shaft 2 is disposed above the central axis of the nozzle 1 through the heat insulation block 11 and supports the nozzle 1, the heat insulation block 11 and the force sensor 16. The VCM 3 is disposed on the central axis of the pressure shaft 2 and drives the movable element 3a in the thickness direction (center axis direction) of the component to move the pressure shaft 2 up and down. The ball screw 4 is disposed with the vertical direction as the axial direction, and is connected to the rotation shaft of the servo motor 6. The rotary shaft servomotor 8 rotates the pressure shaft 2 about the central axis of the pressure shaft 2 via the rotation shaft 15 to position the component P held by the nozzle 1 in the rotation direction.

  The head unit 10 is provided with a nut 5 that is screwed with the ball screw 4, and moves up and down when the ball screw 4 is rotated by driving of the servo motor 6. A force sensor 16 is disposed between the pressure shaft 2 and the heat insulation block 11 to detect a load when the electronic component P is pressed against the circuit board S by the thrust of the VCM 3.

  Next, a specific example of controlling the operation of the conventional component mounting head will be described with reference to FIG. First, the VCM 3 is pressed while maintaining a predetermined thrust at the stroke lower limit by current control. The position of the servo motor 6 is controlled to lower the head unit 10 at a high speed in the direction of the mounting position, the electronic component P comes into contact with the circuit board S of the mounted object, and further lowers by a predetermined pushing amount with respect to the circuit board S. The electronic component P is lowered to the position. Further, the VCM 3 is switched to load feedback control by the force sensor 16 to output a target load.

The target load is pressed by the load feedback control until the predetermined target time has elapsed. Thereafter, the VCM 3 is switched to current control, and the head unit 10 is raised to a predetermined position by position control of the servo motor 6.
JP 2006-147640 A

  However, in the conventional electronic component mounting method, the load feedback control is continued while checking the load value of the force sensor 16 during the operation of the pressing load. Due to the increase in error, the pressure load drifts. This has caused quality problems such as lifting of electronic components, component damage, and short circuit.

  The present invention is directed to solving the problems of the prior art, and an object thereof is to provide an electronic component mounting method that ensures stable mounting load and ensures high mounting quality even when pressing for a long time. And

In order to achieve the above object, an electronic component mounting method according to claim 1 of the present invention is the electronic component mounting method in which the electronic component is brought into contact with the substrate and further pressed against the substrate to be mounted. load control of the pressure means for pressing the electronic component after contact with the raised until initial arrival load P ₁ performs load feedback control based on the detected value of the load detecting means, any time T ₁ is elapsed since After that, load control is performed by switching to current or air pressure control.

Further, the invention described in claim 2 to 6, in the electronic component mounting method of claim 1, the load control of the pressurizing means after the launch until initial arrival load P ₁ until any time T ₁ is passed Performs load feedback control based on the detection value of the load detection means. Thereafter, during load feedback control, the current or air pressure control is performed by the supply amount determined based on the current or air pressure supplied to the pressurization means. performing that, furthermore, a current or air pressure supplied to the pressurizing means after any time T ₁ is passed, it is the average value of the supply amount during load feedback control, also raised until initial arrival load P ₁ After that, the load control of the pressurizing means switches between the load feedback control and the current or air pressure control according to the time from the start of pressing of the electronic component in contact with the board to the completion of pressing. Or switching between load feedback control and current or air pressure control depending on the value of the maximum set load during the pressing period of the electronic component in contact with the substrate, and that the electronic component has contacted the substrate. The detection is performed by a displacement detection means for detecting a displacement that moves in the direction of the mounting position of the electronic component.

Further, in the electronic component mounting method according to any one of claims 1 to 5, the load control performed by the pressurizing unit by the current or air pressure control is the current or air pressure supplied to the pressurizing unit. it is a change in multiple stages, also, at the time launched until initial arrival load P _1, and a value obtained by converting the load is multiplied by a coefficient to the value of current or air pressure supplied to the pressurizing means, the load detecting means Compared with the detected value, when it is detected that the difference exceeds the predetermined value, the warning notification or the mounting operation is stopped, and the pressing load of the pressing means is supplied to the pressing means. Compare the value of the current or air pressure that has been converted into a load by applying a coefficient to the value detected by the load detection means. Action It is characterized by stopping.

According to the mounting method, after the electronic component is in contact with the substrate, up until initial arrival load P ₁ performs load feedback control based on the load detection means, it is after the elapse of an arbitrary time T ₁ of the subsequent , to switch the current or air pressure control, can over time not affected by instability stable component mounting of the load detection means, suppressing the influence of the initial arrival load P ₁ when the contact of the electronic component , It is possible to ensure the mounting quality of electronic parts by detecting abnormalities in the pressurizing means and load detecting means of the mounting device

According to the present invention, after the elapse until any time T _1, by switching the current or pneumatic pressure control from the load feedback control, to suppress the drift of the load for pressing the electronic components, floating of the component joint, the component damage In addition, there is an effect that it is possible to prevent a problem in quality of electronic parts due to mounting such as a short circuit.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic diagram showing a component mounting head of an electronic component mounting apparatus in an electronic component mounting method according to Embodiment 1 of the present invention, and FIG. 2 is a diagram for explaining a specific example for controlling the operation of the component mounting head. FIG. 3 is a view showing a profile of a load applied to the electronic component P.

  Here, components having the same functions corresponding to the components described in FIG. 12 showing the conventional example are given the same reference numerals, and the same applies to the following drawings.

  In FIG. 1, the component mounting head includes a nozzle 1, a pressure shaft 2, a VCM (voice coil motor) 3, a ball screw 4, a nut 5, a servo motor 6, an encoder 7, and a rotary shaft servo motor 8. A rotary shaft encoder 9, a head unit 10, a heater 20, a block 21, a heat insulating block 11, bearings 12, 13 and 14, a rotary shaft 15, a force sensor 16, and a linear scale sensor 22. A scale 23 and a bracket 24 are provided.

  The nozzle 1 holds the electronic component P at its tip by, for example, air pressure (negative pressure). The heater 20 is inserted into the block 21 and supplies heat to the nozzle 1. The heat insulation block 11 is disposed above the block 21 and reduces heat conduction upward by supply air or supply water not shown in the drawing. The pressure shaft 2 is disposed above the central axis of the nozzle 1 via the block 21, the heat insulation block 11, and the force sensor 16, and supports the nozzle 1, the block 21, the heat insulation block 11, and the force sensor 16.

  The VCM 3 serving as a pressurizing unit is disposed on the central axis of the pressurizing shaft 2 and drives the movable element 3a in the thickness direction of the component (the central axis direction) to move the pressurizing shaft 2 up and down. The ball screw 4 is arranged with the vertical direction as the axial direction, and is connected to the rotating shaft of the servo motor 6. The rotary shaft servomotor 8 rotates the pressure shaft 2 about the central axis of the pressure shaft 2 via the rotary shaft 15 to position the electronic component P held by the nozzle 1 in the rotation direction.

  The head unit 10 is provided with a nut 5 that is screwed with the ball screw 4, and moves up and down when the ball screw 4 is rotated by driving of the servo motor 6. The force sensor 16 detects a load when the electronic component P is pressed against the circuit board S by the thrust of the VCM 3. A scale 23 of a linear scale is arranged on the mover 3a of the VCM 3 via a bracket 24, and the displacement amount of the mover 3a can be confirmed by the linear scale sensor 22.

  Next, a specific example of controlling the operation of the component mounting head according to the first embodiment will be described with reference to FIGS.

  First, the VCM 3 is pressed while maintaining a predetermined thrust at the stroke lower limit by current control. The position of the servo motor 6 is controlled to lower the head unit 10 toward the mounting position. At this time, since the detection value of the linear scale sensor 22 changes when the electronic component P comes into contact with the circuit board S of the mounted object, it is determined that the electronic component P has come into contact with the circuit board S.

Further, the electronic component P is lowered to a position where the circuit board S is lowered by a predetermined pushing amount. Then, the VCM 3 is switched from the current control to the load feedback control by the force sensor 16 and is raised to the initial ultimate load P ₁ over an arbitrary time T ₀ , and after the subsequent arbitrary time T ₁ has elapsed, the current control is switched to the current control. A pressing load is applied for a predetermined time. During the current control, the detection value of the force sensor 16 is not referred to, and a control for supplying a predetermined current to the VCM 3 is performed. Thereafter, the head unit 10 is raised to a predetermined position by position control of the servo motor 6.

Thus, after any time T ₁ has elapsed, without the load feedback control by the force sensor 16, by switching to the current control, the pressing load is temporal instability effects not undergo drift of the force sensor 16 It can be suppressed. FIG. 4 shows a comparison between the conventional load profile in the electronic component mounting method and the load profile of the present invention.

  Next, the effect of load stabilization according to the present invention will be described using a semiconductor mounting as an example. FIG. 5 is a cross-sectional view showing before and after the IC chip is bonded to the circuit board. As shown in FIG. 5, an electrode 31 is formed on the IC chip 30, and a gold bump 32 is formed on the electrode 31. Further, an electrode 34 is formed on the surface of the circuit board 33 so as to face the above-described electrode 31, and a thermosetting sheet 35 is pasted on the circuit board 33 in advance. The IC chip 30 is mounted on the circuit board 33 after the electrodes 31 and 34 are aligned, and heat and pressure are applied from above the IC chip 30 to thermally contract the sheet 35 to complete the bonding.

  In order to ensure the bonding quality of semiconductor mounting, it is necessary to apply stable heat and pressure. If the applied pressure (load) is high, the IC chip 30 may have a crack 36 as shown in FIG. 6 or a short circuit 37 as shown in FIG. On the contrary, when the load applied is low, the floating 38 of the gold bump 32 as shown in FIG. 8 may occur.

Therefore, when the joining is completed by applying heat and pressure from above the IC chip 30 in contact with the circuit board 33 shown in FIG. An initial ultimate load P ₁ that does not occur is assumed. Further, the IC chip 30 comes into contact with the circuit board 33 and becomes the initial reached load P ₁ after the lapse of an arbitrary time T _0. After the lapse of the arbitrary time T _{1 when} the load P ₁ is stabilized, the IC chip 30 is placed on the circuit board 33. Join and complete the mounting of the electronic components. As described above, it is possible to reduce the occurrence rate of the bonding failure as described above by the load stabilization of the present invention.

  In the first embodiment, the linear scale sensor 22 confirms that the electronic component P and the circuit board S of the mounted object are in contact with each other, thereby suppressing variations in the push-in amount. As a result, the quality becomes more stable.

Note that the current supplied to the VCM 3 during the current control may be determined based on the current supplied to the VCM 3 during the load feedback control. For example, immediately after the load is raised to the initial ultimate load P _1, when switching from load feedback control to current control and continuing to apply the same load, the VCM 3 was supplied when the initial ultimate load P ₁ was completed. There is a method of continuously supplying current even during current control.

Further, a load of the feedback control after the launch until initial arrival load P _1, the load P ₁ described above to any time T ₁ addition, if also continues to apply a load P ₁ in the subsequent current control, load P in the load feedback control There is a method of obtaining an average value of the current supplied to the VCM 3 when ₁ is added and supplying the current of the average value during the subsequent current control. By these methods, the absolute value accuracy of the load during current control can be further increased, and the mounting quality of the electronic component can be ensured.

Further, initial arrival load P ₁ load control after launch to switches the time width arbitrary time T ₁ by the time to pressing completion from the start of pressing, or until it converges to the initial arrival load P ₁ in pressing period the maximum setting load value that changes, set the time width arbitrary time T _1, it may be switched load feedback control and current control. By this appropriate switching, the load control with the highest load accuracy can be selected, and the mounting quality of the electronic component can be ensured.

Further, the current supplied to the VCM 3 during current control may be changed (increased) in multiple stages. Thus, it is possible to further reduce damage to the electronic component P becomes possible to suppress the influence of the initial arrival load P ₁ and it can be secured mounting quality of the electronic components.

Further, at the time of start-up until initial arrival load P _1, and a value obtained by converting the load is multiplied by a coefficient to a current value supplied to the VCM 3, compared with the value detected by the force sensor 16, the difference is a predetermined value When it exceeds, control to stop the warning notification or mounting operation. This makes it possible to find an abnormality in the current supply means to the force sensor 16 or the VCM 3 and to confirm and maintain the normal operation of the electronic component mounting apparatus, thereby ensuring the mounting quality of the electronic components.

  In addition, when the pressing load is finished, the current value supplied to the VCM 3 is converted into a load by applying a coefficient to the value detected by the force sensor 16, and the difference exceeds a predetermined value. Control is performed so as to stop the warning notification or the mounting operation. As a result, it is possible to find an abnormality in the current supply means to the force sensor 16 or the VCM 3, and the normal operation of the electronic component mounting apparatus can be confirmed and maintained, so that the mounting quality of the electronic component can be ensured.

(Embodiment 2)
FIG. 9 is a schematic diagram showing a component mounting head of an electronic component mounting apparatus in an electronic component mounting method according to Embodiment 2 of the present invention, and FIG. 10 is a diagram for explaining a specific example for controlling the operation of the component mounting head. FIG. 11 is a view showing a profile of a load applied to the electronic component P. In the second embodiment, air pressure control is used instead of the current control in the configuration shown in FIG. 1 of the first embodiment.

  As shown in FIG. 9, 25 is a pressure cylinder, and 25 a is a piston rod of the pressure cylinder 25. By supplying air of a predetermined pressure to the pressurizing cylinder 25, a predetermined thrust is generated in the piston rod 25a. The pressurizing means of the second embodiment is a pressurizing cylinder 25 and a piston rod 25a, which is different from the pressurizing means shown in FIG. 1 of the first embodiment being the VCM 3 and the mover 3a. Since it is the same as Embodiment 1, the description is abbreviate | omitted.

  The same applies to a specific example of controlling the operation of the component mounting head of the second embodiment shown in FIGS. 10 and 11, and as shown in FIGS. 10 and 11, the pressurizing means is different from that of the first embodiment. Therefore, since the operation is the same except that the current control in the first embodiment is the air pressure control, the description thereof is omitted.

Electronic component mounting method according to the present invention, after the elapse until any time T _1, by switching the current or pneumatic pressure control from the load feedback control, to suppress the drift of the load for pressing the electronic component, the component bonding portion It is possible to prevent problems with the quality of electronic components associated with mounting, such as lifting, component damage, and circuit shorting, and it is useful as a method for mounting electronic components on a circuit board.

Schematic which shows the component mounting head of the electronic component mounting apparatus in Embodiment 1 of this invention. The figure explaining the specific example which controls operation | movement of the component mounting head of this Embodiment 1. FIG. The figure which shows the profile of the load added to the electronic component P of this Embodiment 1. The figure which shows the comparison of load profile of former and this invention Sectional drawing which shows before and after joining an IC chip to a circuit board The figure which shows the crack which arose in IC chip by joining The figure which shows the short circuit which arose in IC chip by joining The figure which shows the float which arose in IC chip by joining Schematic which shows the component mounting head of the electronic component mounting apparatus in Embodiment 2 of this invention. The figure explaining the specific example which controls operation | movement of the component mounting head of this Embodiment 2. FIG. The figure which shows the profile of the load added to the electronic component P of this Embodiment 2. Schematic showing a component mounting head of a conventional electronic component mounting apparatus The figure explaining the specific example which controls operation | movement of the conventional component mounting head.

Explanation of symbols

1 Nozzle 2 Pressure shaft 3 VCM
3a Movers 4 Ball screw 5 Nut 6 Servo motor 7 Encoder 8 Rotating shaft servo motor 9 Rotating shaft encoder 10 Head unit 11 Heat insulation block 12, 13, 14 Bearing 15 Rotating shaft 16 Force sensor 20 Heater 21 Block 22 Linear scale sensor 23 Scale 24 Bracket 25 Pressure cylinder 25a Piston rod 30 IC chip 31, 34 Electrode 32 Gold bump 33 Circuit board 35 Sheet 36 Crack 37 Short circuit 38 Floating

Claims (9)

In the electronic component mounting method in which the electronic component is brought into contact with the substrate and further pressed against the substrate to be mounted,
Load control of the pressure means for pressing the electronic component after contact with the substrate, up until initial arrival load P ₁ performs load feedback control based on the detected value of the load detecting means, any time since T An electronic component mounting method characterized in that after ₁ elapses, load control is performed by switching to current or air pressure control. The initial arrival load P ₁ load control of the pressurizing means after the launch until the until any time T ₁ is elapsed performs load feedback control based on the detected value of the load detecting means, thereafter the load feedback control 2. The electronic component mounting method according to claim 1, wherein current or air pressure control is performed by a supply amount determined based on the current or air pressure supplied to the pressurizing means. The arbitrary time T ₁ is passed to a current or air pressure supplied to the pressurizing means after the electronic component mounting method according to claim 2, characterized in that the average value of the supply amount in the load feedback control. The initial load control of the pressurizing means after the launch reached the load P _1, depending on the time from contact with the start of pressing of the electronic component to the substrate until the pressing completion, the load feedback control and current or air pressure control The electronic component mounting method according to claim 1, wherein the electronic component mounting method is switched. Load control of the pressurizing means after the launch until said initial arrival load P ₁ is the maximum set load value during the pressing period of the electronic component in contact with the substrate, and a control load feedback control and current or air pressure The electronic component mounting method according to claim 1, wherein switching is performed.   2. The electronic component mounting method according to claim 1, wherein the detection of the contact of the electronic component with the substrate is performed by a displacement detection unit that detects a displacement that moves in a direction of the mounting position of the electronic component.   6. The load control performed by the pressurizing unit by the current or air pressure control changes the current or air pressure supplied to the pressurizing unit in multiple stages. Electronic component mounting method. Wherein in the initial time of arrival launched load to P _1, compares the value obtained by converting the load is multiplied by a coefficient to the value of current or air pressure supplied to the pressurizing means, and a value detected by the load detection unit, the difference 6. The electronic component mounting method according to claim 1, wherein the warning notification or the mounting operation is stopped when it is detected that the value exceeds a predetermined value.   At the time when the pressing load of the pressurizing means is finished, the value converted to the load by multiplying the value of the current or air pressure supplied to the pressurizing means by a coefficient is compared with the value detected by the load detecting means. The electronic component mounting method according to claim 1, wherein when the difference is detected to exceed a predetermined value, the warning notification or the mounting operation is stopped.

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