JP2008182111A - Substrate fixing device - Google Patents

Abstract

A substrate that is positioned and fixed is deformed such as warping, and even when the strength is low, the deformation can be surely eliminated and flattened.
In the control means for controlling the distance between the first holding means and the second holding means for holding both ends of the substrate based on the height of the substrate measured by the height measuring means, the height measurement is performed. Means for setting, for each type of substrate, a threshold value that defines an allowable limit of deviation between the substrate height measured by the means and the reference height, and the interval between the first holding means and the second holding means is increased by the interval adjusting means. On the other hand, a step (step 8) for determining whether or not the deviation between the substrate height (step 7) measured by the height measuring unit and the reference height is equal to or less than a corresponding threshold is realized. Yes.
[Selection] Figure 5

Description

  The present invention relates to a substrate fixing device, and more particularly to a substrate fixing device capable of correcting deformation such as bending or warping that has occurred on a printed circuit board positioned at a position where an electronic component is mounted.

  As shown in FIG. 6, the surface mounting device for mounting electronic components on a printed circuit board or the like can be mounted with a nozzle that attracts the electronic components, and the mounted nozzle is positioned in the vertical and rotational directions. Head unit 10 capable of transporting, positioning the head unit 10 in the X direction and positioning the X drive unit 12, transporting and positioning the head unit 10 in the Y direction integrally with the X drive unit 12, and electronic components The component supply unit 16 supplies the printed circuit board S, the substrate transfer unit 18 that loads the printed circuit board S and carries it out after mounting the components, the nozzle replacement unit 20 that holds the replacement nozzle, and the like.

  In such a surface mounting apparatus, the head unit 10 is positioned on the component supply unit 16 by the X driving unit 12 and the Y driving unit 14, the shaft built in the head unit 10 is lowered, and the lower end thereof Parts are adsorbed by the mounted nozzle.

  At that time, as disclosed in Patent Document 1, for example, the height sensor (height measuring means) 22 attached to the head unit 10 is attached to the component supply unit 16 so that the component can be accurately attracted to the nozzle. The height to the upper surface of the supplied component is also measured.

  After adsorbing the components as described above, the head unit 10 is positioned on a predetermined placement position on the printed circuit board fixed to a predetermined position of the substrate transport unit 18 by the X driving unit 12 and the Y driving unit 14, Thereafter, the shaft is lowered, and the components that have been adsorbed by the nozzle are mounted on the printed circuit board S.

  As shown in FIG. 7, when the printed circuit board S is carried in by a transport belt (not shown), the substrate transport section 18 is stopped by the positioning section 30 and is positioned and fixed. The components are mounted, and the mounted substrate S is carried out downstream by the conveyor belt.

  Conventionally, in the positioning unit 30, when the substrate S is stopped at the fixed position, the backup motor 32 is driven to raise the backup table 34, whereby the substrate fixing pins 36 on the backup table 34 are used to lower the lower surface of the substrate S. The substrate is fixed by holding both opposing ends with a substrate fixing device.

  The features of this substrate fixing device are shown in the exploded perspective views of FIGS. FIG. 8 corresponds to a cross-sectional view schematically showing a part of the positioning unit 30 in a direction orthogonal to the transport direction of the substrate transport unit 18, and shows one transport rail and its vicinity enlarged.

  A conveyance rail 40 that carries the printed board S into and out of the positioning unit 30 is supported by a conveyance rail support 42, and a substrate pressing plate 44 is fixed to the upper end of the support 42 by a fixing screw 42A. Yes.

  A bearing base 46 mounted in a hole 40A formed in the transport rail 40 is fixed to the inner side surface of the transport rail support base 42, and the transport rail is supported by a slide shaft 48 that slides in the bearing 46A. The transport rail 40 is guided in the vertical direction with respect to the support base 42 so that it can move in the vertical direction integrally with the backup table 34.

  An endless transport belt 50 is wound around the transport rail 40, and the printed circuit board S placed thereon is moved along the substrate guide 40B by being driven to rotate on the transport rail 40 by a motor (not shown). It is conveyed in a direction perpendicular to the paper surface.

  When the printed circuit board S is carried into a predetermined position and positioned by the transport belt 50 in this way, the transport rail 40 is mechanically lifted by the raising of the backup table 34, and the transport belt as shown in FIG. The printed circuit board S on 50 is pressed against the substrate pressing plate 44 fixed to the upper end of the transport rail support base 42. Thus, the opposing both ends of the printed circuit board S are clamped and fixed by being sandwiched between the substrate pressing plate 44 and the transport belt 48 (transport rail 40).

  In the case of a conventional general printed circuit board, it can be fixed in a flat state following the shape of the transport rail 40 by sandwiching the opposite ends as described above.

JP-A-8-51297

  However, along with the recent reduction in size and weight of electronic devices, the thickness of printed circuit boards has been reduced, and film materials have been increasingly used. Therefore, the warping and bending of printed circuit boards themselves are large. In addition, since the material is soft, there are many cases where it is not possible to eliminate all the bending (warping) of the central portion even if the both ends are sandwiched.

  In this way, if the top surface of the printed circuit board is not flat, the mounting position of the electronic components will be greatly displaced, and the mounting position will not be sufficient due to the adhesive or solder paste. There is a problem of causing a malfunction such as a change.

  The present invention has been made to solve the above-mentioned conventional problems. Even when the substrate positioned and fixed at a predetermined position is deformed such as warping or bending, and even when the strength of the substrate is low, It is an object of the present invention to provide a substrate fixing device that can be flattened by eliminating deformation, and as a result, can accurately mount components on the substrate.

  The present invention provides a first holding means and a second holding means for holding opposite opposing ends of a positioned substrate, an interval adjusting means for adjusting an interval between the first holding means and the second holding means, and a first holding means. Height measuring means for measuring the height of the substrate held at both ends by the means and the second holding means, and the first holding means and the second holding means by the interval adjusting means based on the measured height of the substrate. And a control unit for controlling the interval between the substrate height and the threshold value for defining a permissible limit of deviation between the substrate height measured by the height measuring unit and a reference height for each substrate type. It is determined whether the deviation between the substrate height measured by the height measuring means and the reference height is equal to or less than a threshold value while widening the interval between the first holding means and the second holding means by the setting means and the interval adjusting means. Means By a, it is obtained by solving the above problems.

  According to the present invention, the control means sets a unit change amount for expanding the interval between the first holding means and the second holding means by the interval adjusting means for each substrate type when measuring the substrate height. May be included.

  In the invention, it is preferable that the control means includes means for setting, for each type of substrate, a changeable amount that defines a maximum width by which the interval between the first holding means and the second holding means is expanded by the interval adjusting means. Also good.

  In the present invention, the type of the substrate may be classified at least by thickness and material.

  According to the present invention, the positioned substrate is held and fixed at both opposite ends, and the first holding is performed based on the height of the substrate surface measured at one or more locations of the substrate at that time. When controlling the distance between the means and the second holding means, the deviation between the measured substrate height and the reference height should be less than or equal to the threshold value set for each type of substrate. Therefore, it is possible to eliminate deformation such as warping that has occurred in the substrate without breaking the substrate.

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

  FIG. 1 is a cross-sectional view schematically showing a substrate fixing apparatus according to an embodiment of the present invention.

  The board fixing device of the present embodiment is installed in the positioning unit 30 shown in FIG. 7. When the printed board S is transported and positioned by the board transport unit 18 to the positioning unit 30, A first gripping means 60 and a second gripping means 62 are provided for gripping both opposing ends.

  Since these first and second gripping means 60 and 62 are substantially the same as those shown in FIGS. 8 and 9, the same reference numerals are used and detailed description thereof is omitted.

  In the present embodiment, the first bracket 66A and the second bracket 66B are fixed to the frame bottom portion 64 of the substrate transport section 18 at positions facing each other, and both the brackets 66A and 66B are respectively connected via bearings 68A and 68B. The ball screw 70 is pivotally supported.

  A driven pulley 72A is connected to one end of the ball screw 70, and the driving force of the stepping motor 74 is passed through a timing belt 76 wound around the driving pulley 72B connected to the stepping motor 74. Is transmitted and the ball screw 70 is rotated.

  Further, a ball screw nut portion 78 is inserted into the ball screw 70, and the stepping motor 74 is driven in a state in which the rotation of the nut portion 78 is restricted, so that the ball screw 70 can move in the left-right direction in the figure. .

  The first gripping means 60 is fixed to the first bracket 66A via the transport rail support 42, and the second gripping means 62 is fixed to the ball screw nut portion 78 via a support member. Accordingly, the distance between the fixed conveyance rail 40 of the first clamping means 60 and the movable conveyance rail 40 of the second clamping means 62 can be adjusted by the ball screw nut portion 78 that reciprocates as the ball screw 70 rotates. The ball screw 70, the stepping motor 74, the ball screw nut portion 78, and the like constitute interval adjusting means.

  As shown in FIG. 2, the substrate fixing device of the present embodiment extracts the first and second holding means 60 and 62 and the printed circuit board S held at both ends of the first and second holding means 60 and 62. Is provided with a height sensor 22 for measuring the height up to. Specifically, the height sensor 22 is fixed to the head unit 10 as shown in FIG. 6, and the height is measured as the distance from the head unit 10 to the upper surface of the printed circuit board S. It has become.

  In the present embodiment, based on the height of the substrate S measured by the height sensor 22, the stepping motor (interval adjusting means) 74 is rotated by the control device (control means) schematically shown in FIG. The distance between the first gripping means 60 and the second gripping means 62 is controlled.

  That is, when a sensor detection signal from the height sensor 22 is input to the CPU 82 via the I / O interface 80, the first and second holding means are based on reference data stored in the memory 84 in advance. Control for eliminating deformation such as warpage of the printed circuit board S is calculated by calculating an adjustment amount of the interval between 60 and 62 and outputting a control signal to the stepping motor 74 via the motor driver 86 based on the calculation result. Is possible.

  In the present embodiment, the CPU 82 and the memory 84 included in the control means set a threshold value that defines an allowable limit of deviation between the substrate height measured by the height sensor 22 and the reference height for each substrate type. The gap between the first gripping means 60 and the second gripping means 62 is widened by the means and the distance adjusting means, and it is determined whether the deviation between the substrate height measured by the height measuring means and the reference height is equal to or less than a threshold value. The means is realized by software.

  Further, when measuring the substrate height, the interval adjusting unit, together with the unit for setting the unit change amount for expanding the interval between the first holding unit 60 and the second holding unit 62 by the interval adjusting unit, by the interval adjusting unit. The means for setting the changeable amount for defining the maximum width for expanding the interval between the first gripping means 60 and the second gripping means 62 for each type of substrate is similarly realized by software.

  FIG. 4 shows an example of the substrate (reference) data set in the data table of the memory 84 for each type of part defined by the material, shape, thickness, etc., and stored as part of the production program. Show. Here, the rail width means an interval between the first and second gripping means 60 and 62.

  Next, the operation of this embodiment will be described in detail with reference to the flowchart of FIG.

  First, in step 1, substrate data is read from a production program. Position coordinates of the four corners of the substrate for calculating the reference height for determining whether the warp is warped from the substrate size: SD1, and height sensor position for reading the state of the warp by height: SD2 (basically the center of the substrate Get nearby coordinates. In addition, from the substrate material and substrate thickness data, the threshold value for warpage judgment for protecting the substrate as illustrated in FIG. 4 above: SD3, rail width change unit amount (the rail for each height measurement) The amount by which the width is finely moved): SD4 and the rail width change amount possible amount: SD5 are acquired.

  When the printed circuit board S is carried in from the previous process and reaches the positioning unit 30 on which the electronic component is mounted by the substrate transport unit 18, the backup table 34 rises and the left and right transport rails 40, 40 that support both ends of the printed circuit board S are supported. The both ends of the printed circuit board S are held as shown in FIG. As shown in the drawing, at this point, the printed circuit board S is bent near the center. In this example, the case of upward warping in which the central portion is convex is shown, but depending on the situation, there is also the case of downward warping becoming concave.

  When the holding / fixing of the printed circuit board S is completed as described above, the reference height is acquired in Step 2. Specifically, the head portion 10 shown in FIG. 6 is moved XY, and the vicinity of both ends in the width direction holding the printed circuit board S indicated by B and C in FIG. 2 is attached to the head portion 10. The height sensor 22 is used for measurement. This measurement is also performed at the front and rear substrate edges perpendicular to the paper surface in the figure, and a total of four reference positions corresponding to the position coordinates of the four corners of the substrate acquired in step 1 are measured.

  Based on the measured heights and measured coordinates at the four locations, the CPU 82 calculates the reference height when the substrate center portion indicated by A in the figure is not bent, and the reference value is stored in the memory 84.

  In the device structure of the present embodiment, the heights of the four corners of the substrate are mechanically limited to a constant value by holding both ends of the substrate. Therefore, the height values of the four corners of the substrate are measured each time the substrate is held. Even if it is not performed, it may be performed only once at the time of assembly / adjustment of the surface mounting apparatus or at the time of lot switching of each board production.

  Next, in step 3, the height sensor 22 is moved to the substrate center A (SD2), and in step 4, the substrate height at that position is measured and acquired, and the measured value and the substrate edge are measured. A deviation from the obtained reference value is obtained.

  Thereafter, in step 5, the height measured in step 4 is compared with the reference height calculated from the heights of the four corners of the substrate, and the deviation is compared with the threshold value SD3 for warpage determination. If it is also a small value (Y), the operation is completed assuming that the warp is sufficiently small.

  On the other hand, if it is determined as a result of the comparison in step 5 that the deviation of the substrate height is larger than the threshold value (N), the stepping motor 74 is driven so that this deviation becomes smaller, and the second gripping means 62 is driven. Is moved in the direction of arrow A so that the distance between the two conveying rails 40, 40 arranged facing each other is increased. In that case, after the operation of increasing the rail width by the rail width change unit amount: SD4 is performed in Step 6, the height of the substrate upper surface at the warpage determination position is measured again in Step 7.

  In step 8, the height measured in step 7 is compared with the reference height calculated from the heights of the four corners of the substrate, and in the same way as in step 5, the deviation is compared with the threshold value SD3 for warpage determination. If the value is small, the warp is sufficiently small and the operation is completed.

  On the other hand, if the result of determination in step 8 is greater than the threshold value, it is compared in step 9 whether the value of the rail width at that time is greater than the rail width changeable amount: SD5, and is smaller. Returns to step 6 and repeats the series of operations up to step 8.

  On the other hand, if the rail width value exceeds the rail width changeable amount: SD5 in step 9, an error message is displayed in step 10 because there is a possibility that the board is damaged or deformed. To complete the operation.

  As described above in detail, by causing the printed circuit board S to be pulled to both sides, the amount of bending is extended, and deformation such as warping is eliminated. At that time, the height sensor 22 continues to measure the height of the central portion A of the printed circuit board S as in Steps 6 to 8, and when the deviation from the reference value is equal to or less than a preset threshold value, or Step When the distance between the two transport rails 40, 40 arranged facing each other at 9 is moved by a predetermined amount or more, the driving of the stepping motor 74 is stopped and the control operation is ended.

  In general, the material of the substrate is various such as glass epoxy, paper, ceramic, polyimide, metal, etc., and the thickness is widely used from several tens μm to several mm. In addition, since the shape is not constant or is not constant, if the both ends are pulled in the width direction to eliminate the bending of the substrate, the substrate itself may be damaged. On the other hand, when the both ends of the substrate are pulled with a weak force, the bending of a hard material such as metal may not be eliminated.

  According to the embodiment described above in detail, by adjusting the moving force of the movable conveyance rail according to the substrate material and thickness, only a force necessary and sufficient to correct the bending of the substrate can be given. And damage to the substrate can be suppressed.

  Accordingly, deformation such as warping of the printed circuit board can be eliminated without damaging the board, so that the mounting accuracy of electronic components can be improved and problems such as mounting position deviation can be solved. . In addition, when deformation such as warping of the printed circuit board cannot be eliminated due to breakage or the like, the operation can be stopped by an error signal, so that it is possible to prevent occurrence of a component mounting defective board.

  In addition, since the distance between the first gripping means 60 and the second gripping means 62 is feedback-controlled by the height sensor based on the actual measurement value of the board height, the control operation is ensured and the printed board is not fixed properly. Can be prevented.

  Note that the measurement position by the height sensor 22 for determining the degree of deformation of the printed circuit board S may be a plurality of positions determined in advance as shown in the above embodiment, but arbitrary coordinates are selected. You may do it.

  That is, when measuring a plurality of locations, as described above, it is effective for detecting the situation when the amount of deformation at the front, rear, left and right is not constant. This is effective when, for example, an electronic component that requires high mounting position accuracy is mounted.

  Also, even when the height of the printed circuit board is measured at a plurality of locations, it may not be the above four locations, but may be two locations such as the left front and the right back, increasing the number of measurement locations to five or six. May be.

Sectional drawing which shows typically the board | substrate fixing apparatus of 1st Embodiment concerning this invention. Explanatory drawing which shows the principle which measures the height of the printed circuit board fixed with the board | substrate fixing apparatus of this embodiment The block diagram which shows the outline | summary of the control system with which the board | substrate fixing apparatus of this embodiment is provided. Chart showing an example of board data set for each board type Flow chart showing the operation of this embodiment Plan view showing the outline of surface mount equipment Enlarged perspective view showing the outline of the board transfer section provided in the surface mount device The fragmentary sectional view which shows typically the characteristic of the board | substrate fixing apparatus which the said board | substrate conveyance part has Exploded perspective view showing features of the substrate fixing device

Explanation of symbols

DESCRIPTION OF SYMBOLS 22 ... Height sensor 30 ... Positioning part 32 ... Backup motor 34 ... Backup table 36 ... Backup pin 40 ... Conveyance rail 42 ... Conveyance rail support base 44 ... Substrate holding plate 46 ... Bearing stand 48 ... Slide shaft 50 ... Conveyance belt 60 ... 1st clamping means 62 ... 2nd clamping means 64 ... Frame bottom part 66 ... Bracket 68 ... Bearing 70 ... Ball screw 72 ... Pulley 74 ... Stepping motor 76 ... Timing belt 78 ... Ball screw nut part 82 ... CPU
84 ... Memory

Claims (4)

A first gripping means and a second gripping means for gripping both opposing ends of the positioned substrate,
An interval adjusting means for adjusting an interval between the first holding means and the second holding means;
Height measuring means for measuring the height of the substrate held at both ends by the first holding means and the second holding means;
Control means for controlling the interval between the first holding means and the second holding means by the interval adjusting means based on the measured height of the substrate, and
The control means is
Means for setting, for each type of substrate, a threshold value that defines an allowable limit of deviation between the substrate height measured by the height measuring means and a reference height;
Means for determining whether a deviation between a substrate height measured by the height measuring means and a reference height is equal to or less than a threshold value while expanding a distance between the first gripping means and the second gripping means by the spacing adjusting means. The board | substrate fixing device characterized by the above-mentioned. The control means is
2. The apparatus according to claim 1, further comprising means for setting, for each type of substrate, a unit change amount by which the interval between the first holding means and the second holding means is expanded by the interval adjusting means when measuring the substrate height. The board | substrate fixing apparatus of description. The control means is
2. The substrate according to claim 1, further comprising means for setting, for each type of substrate, a changeable amount that defines a maximum width by which the interval between the first holding unit and the second holding unit is expanded by the interval adjusting unit. Fixing device.   3. The substrate fixing device according to claim 1, wherein the type of the substrate is classified at least by a thickness and a material.

Images