JP3903723B2 - Mounting method of conductive balls - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention, conductive balls by adsorbed relates tower mounting method of the conductive ball to be mounted on a predetermined position.
[0002]
[Prior art]
As a method for forming metal bumps on electrodes of a substrate or an electronic component, a method is known in which a conductive ball such as a solder ball (hereinafter simply referred to as “ball”) is mounted on an electrode and soldered. For mounting the ball, a method of vacuum-sucking the ball with a mounting head is widely used. In this method, a ball is sucked into a plurality of suction holes provided on the lower surface of the suction head of the mounting head, the suction head is moved, and the vacuum suction is released to mount the ball at a predetermined position.
[0003]
As a method of attracting the ball to the lower surface of the suction head, instead of the method of lowering the suction head with respect to the ball tank storing a large number of balls and directly attracting and holding the ball on the lower surface of the suction head, the suction head suction A method has been adopted in which conductive balls are arranged in an alignment portion in which concave portions are formed at positions corresponding to the hole arrangement. This method has the advantage that the ball can be quickly and correctly held in each suction hole of the suction head during ball pickup.
[0004]
[Problems to be solved by the invention]
However, the method of previously aligning the balls in the alignment portion has the following problems in the ball suction operation. In this method, in order to correctly and quickly attract the aligned balls to the suction head, the alignment between the alignment portion and the suction head, that is, the relative position between the concave portion of the alignment portion containing the balls and the suction hole of the suction head is accurate. It is necessary to match well. However, since the lower surface of the suction head and the upper surface of the alignment portion are opposed to each other at the close position at the time of alignment, it is difficult to visually confirm the appropriateness of the alignment state in this state, and accurate alignment is difficult.
[0005]
The present invention is appropriately aligned with the alignment part and the suction head carried, and an object thereof is to provide tower mounting method of the conductive balls can prevent problems in ball suction operation.
[0014]
[Means for Solving the Problems]
The method of mounting a conductive ball according to claim 1 is a method of mounting a conductive ball that holds the conductive ball and mounts the conductive ball at a predetermined position, and a concave portion that can accommodate one conductive ball is provided on the upper surface. A plurality of conductive balls disposed in each of the alignment portions having an internal space that communicates with the recesses, and are sucked by a suction head having suction holes corresponding to the array. In operation, based on the detection results of the first pressure detection means and the second pressure detection means for detecting the first pressure in the suction head and the second pressure in the internal space of the alignment unit, respectively, The suitability of the relative position with respect to the alignment portion is determined.
[0016]
According to the present invention, the first pressure in the suction head in the ball suction operation for sucking the conductive balls from the alignment portion in which a plurality of recesses capable of accommodating one conductive ball in a predetermined arrangement is provided on the upper surface. And determining whether the relative position of the suction head relative to the alignment portion is appropriate based on the detection results of the first pressure detection means and the second pressure detection means for detecting the second pressure in the internal space of the alignment portion, respectively. As a result, it is possible to accurately determine whether or not the relative position of the suction head with respect to the alignment portion during the ball suction operation is appropriate and whether or not there is a mistake in suction of the conductive ball by the suction head.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a conductive ball mounting device according to an embodiment of the present invention, and FIG. 2 is a view of a suction hole of a suction head and a recess of an alignment portion of the conductive ball mounting device according to an embodiment of the present invention. FIG. 3 is an explanatory diagram, FIG. 3 is a block diagram showing the configuration of the vacuum suction system and the control system of the conductive ball mounting apparatus according to the embodiment of the present invention, and FIGS. 4 and 5 are the conductivity of the embodiment of the present invention. FIG. 6 is an explanatory view of the pressure change in the ball suction operation, FIG. 6 is an explanatory view of the alignment of the suction head and the alignment portion in the conductive ball suction operation of the embodiment of the present invention, and FIGS. It is explanatory drawing of the adsorption | suction mistake in the adsorption | suction operation | movement of the conductive ball of one Embodiment.
[0018]
First, the overall structure of the conductive ball mounting apparatus will be described with reference to FIG. In FIG. 1, a positioning table 2 is provided on a base 1, and a substrate 3 is held on the positioning table 2. The substrate 3 is positioned at a predetermined position by driving the positioning table 2. On the side of the positioning table 2, a ball supply unit 4 that supplies conductive balls 6 (hereinafter simply referred to as “balls 6”) in an aligned state is disposed. The ball supply unit 4 is provided with an alignment jig 5 for balls 6, and the alignment jig 5 is provided with a recess 7 (see also FIG. 2) for receiving only one ball 6 in a predetermined arrangement. 5a. Around the alignment portion 5 a is a storage portion 5 b for storing the balls 6.
[0019]
The alignment jig 5 can be rotated around the rotation shaft 8a by a predetermined angle by an inclination mechanism 8, and the alignment jig 5 is inclined from a horizontal position by this rotation. By this inclination, the balls 6 in the storage part 5b can be moved onto the alignment part 5a and accommodated in the recesses 7 of the alignment part 5a.
[0020]
Next, the mounting mechanism 10 for mounting the ball 6 will be described. A moving table 11 including a positioning table 2 and a ball supply unit 4 as a moving range is disposed above the base 1. A movable plate 11a is mounted on the movable table 11 so as to be horizontally movable. A four-axis moving mechanism 12 is coupled to the moving plate 11a. A suction head 13 is attached to the four-axis movement mechanism 12, and the suction head 13 can be moved in the X, Y, and Z directions and rotated in the θ direction by the four-axis movement mechanism 12.
[0021]
As shown in FIG. 2A, on the lower surface of the suction head 13, a plurality of suction holes 13a for holding the ball 6 by vacuum suction are provided. The arrangement of the recesses 7 of the alignment portion 5a described above corresponds to the arrangement of the suction holes 13a of the suction head 13. The suction head 13 is aligned with the alignment portion 5a and the lower surface of the suction head 13 is aligned. Are arranged on the upper surface of the alignment portion 5a with a predetermined gap, so that each of the plurality of suction holes 13a arranged in a lattice shape faces the recess 7. In this state, the inside of the suction head 13 is vacuum-sucked, whereby the balls 6 accommodated in the recesses 7 of the alignment portion 5a can be vacuum-sucked and held in the suction holes 13a. Then, the suction head 13 holding the ball 6 is moved onto the positioning table 2 holding the substrate 3, and the suction head 13 is moved up and down with respect to the substrate 3, whereby the ball 6 held by the suction head 13 is moved. Mounted on the substrate 3.
[0022]
In this ball adsorbing operation, in order to adsorb the ball 6 to each adsorbing hole 13a quickly, it is necessary to accurately align the adsorbing hole 13a and the recess 7. That is, because of the position variation due to manufacturing errors of the suction holes 13a and the recesses 7, and the alignment error between the suction head 13 and the alignment portion 5a, the suction holes 13a and The position does not completely coincide with the concave portion 7 and is shifted in the horizontal direction. In the conductive ball mounting apparatus shown in the present embodiment, the degree of vacuum in the suction head 13 and in the alignment portion 5a is detected as described below so that this positional deviation can be minimized and the ball suction can be performed without problems. Based on the result, the suitability of the relative position is determined.
[0023]
Next, the configuration of the vacuum suction system and the control system of the ball 6 mounting device will be described with reference to FIG. In FIG. 3, an inner space 7 b that communicates with the recess 7 is provided on the lower surface of the alignment portion 5 a, and a conduit 7 c that communicates with the inner space 7 b is connected to a vacuum suction source 16 via a suction control valve 14. ing. Similarly, the pipe line 13 d communicating with the suction head 13 is connected to the vacuum suction source 16 via the suction control valve 15.
[0024]
The suction control valves 14 and 15 are connected to the suction control unit 17, and the suction control valves 17 and 15 are controlled by the suction control unit 17 in a state where the vacuum suction source 16 is driven. The vacuum suction ON-OFF and the vacuum suction force can be controlled from the suction hole 13 a of the suction head 13.
[0025]
Detection points A and B of pressure sensors PS1 and PS2 for detecting the degree of internal vacuum are set in the suction head 13 and the internal space 7b of the aligning portion 5a, respectively, and are detected by the pressure sensors PS1 and PS2. The pressure detection signals at points A and B are transmitted to the pressure detector 19. Based on these pressure detection signals, the pressure detection unit 19 detects the degree of vacuum in the suction head 13 and the internal space 7b of the alignment unit 5a. As will be described later, the detection result is used for determination of a suction error by the determination unit 20 and determination of suitability of the relative position of the suction head 13 with respect to the alignment unit 5a in the ball suction operation.
[0026]
The pressure sensor PS1 and the pressure detection unit 19 serve as first pressure detection means (adsorption head pressure detection means) for detecting a first pressure indicating the degree of vacuum in the suction head 13 during the ball suction operation. The PS2 and the pressure detection unit 19 are second pressure detection means (alignment part pressure detection means) for detecting a second pressure indicating the degree of vacuum in the internal space 7b of the alignment part 5a during the ball suction operation.
[0027]
The mechanism control unit 18 controls the operation of the mounting mechanism 10. The determination unit 20 determines the presence or absence of a suction error of the ball 6 by the suction head 13 based on the pressure detection result in the suction head 13 by the pressure detection unit 19 and in the internal space 7b of the alignment unit 5a. The suction control unit 17, the mechanism control unit 18, the pressure detection unit 19, and the determination unit 20 constitute a control unit 23 that controls the ball suction operation and the mounting operation.
[0028]
The display unit 21 is a display monitor such as a CRT, and displays the pressure detection result in the suction head 13 and the internal space 7b of the alignment unit 5a by the pressure detection unit 19 and the determination result by the determination unit 20. The operation / input unit 22 is an input unit such as a keyboard, and inputs various data and operation commands to the control unit 23.
[0029]
4 and 5, the alignment state when the balls 6 aligned with the alignment portion 5a are attracted by the suction head 13 and the pressure in the suction head 13 and the internal space 7b of the alignment portion 5a. The relationship with will be described. FIG. 4A shows a state in which the relative positions of the suction head 13 and the alignment portion 5a are correctly aligned, and the suction holes 13a and the recesses 7 are aligned without causing any positional deviation. FIG. 4B shows the time of the pressure at the detection point A in the interior 13c of the suction head 13 and the detection point B in the internal space 7b of the alignment portion 5a in the above state (relative pressure with the atmospheric pressure equivalent pressure being 0). Changes.
[0030]
In the state shown in FIG. 4A, since there is no displacement between the suction hole 13a and the recess 7, the ball 6 in the recess 7 is sucked from the suction hole 13b in a short time when the suction head 13 is vacuumed. It is captured by the force and adsorbed to the adsorption hole 13a. As a result, the suction hole 13b is closed, so that the pressure at the detection point A in the suction head 13 matches the suction pressure of the vacuum suction source 16, as shown by the pressure detection line L (A) in FIG. The vacuum level is reduced.
[0031]
At this time, since the internal space 7b of the alignment portion 5a is not sucked by vacuum, the pressure at the detection point B is substantially equal to the atmospheric pressure regardless of the passage of time, as indicated by the pressure detection line L (B). That is, a differential pressure ΔP is generated between the two pressure detection lines L (A) and L (B) at the timing when the ball 6 is attracted.
[0032]
Next, the case where the relative positions of the suction head 13 and the alignment portion 5a are shifted will be described. In this case, as shown in FIG. 5 (a), the suction hole 13a and the concave portion 7 are in a misaligned state, and the ball 6 remains in the concave portion 7 without being attracted to the suction hole 13a. FIG. 5B similarly shows temporal changes in pressure at the detection points A and B during the adsorption operation.
[0033]
In the state shown in FIG. 5A, due to the positional displacement between the suction hole 13a and the recess 7, the ball 6 in the recess 7 remains in the recess 7 without being attracted to the suction hole 13a even if the suction head 13 is vacuum-sucked. It shows unstable behavior that moves randomly in the vertical and horizontal directions. For this reason, the suction hole 13 b is not closed by the ball 6, and the suction hole 13 b is in communication with the suction hole 7 a of the recess 7.
[0034]
If the vacuum suction inside the suction head 13 is continuously performed in this state, the internal space 7b of the alignment portion 5a is also vacuum suctioned as indicated by an arrow a. As a result, as shown by pressure detection lines L (A) and L (B) in FIG. 4B, the pressure at the detection point A and the pressure at the detection point B are substantially equal. That is, the differential pressure ΔP hardly occurs between the two pressure detection lines L (A) and L (B).
[0035]
As described above, when the suction head 13 sucks the balls 6 from the alignment portion 5a, as shown in FIG. 4A, if the balls 6 are correctly sucked in all the suction holes 13a. The differential pressure ΔP between the detection points A and B appears clearly. On the other hand, as shown in FIG. 5A, when the ball 6 is not correctly attracted to the suction hole 13a, the pressure at the detection point B follows the pressure at the detection point A. Does not occur.
[0036]
Therefore, at the time of teaching the suction position where the suction head 13 is aligned with the alignment portion 5a, it is possible to determine whether or not the alignment is appropriate based on the pressure detection results of the detection points A and B as described above. That is, the differential pressure ΔP in a correctly aligned state is obtained by actual measurement and set as a threshold value, and the relative position between the suction head 13 and the alignment portion 5a that satisfies the threshold condition is Obtain as the correct suction position.
[0037]
Hereinafter, the suction position will be described with reference to FIG. FIG. 6A is a plan view showing a state in which the suction head 13 is lowered onto the alignment portion 5a of the alignment jig 5 during ball suction. In this alignment, a center point 13d (defined by the center of gravity of the lower surface of the suction head 13) defined to representatively indicate the position of the suction head 13 is set to a specific coordinate point (X0, Y0, Z0). In addition, the direction line L indicating the direction of the suction head 13 is matched with the specific angle θ0.
[0038]
By this alignment, a specific coordinate point where a large number of recesses 7 provided in the alignment portion 5a and a large number of suction holes 13a on the lower surface of the suction head 13 face each other without causing a large deviation on average. And an optimal adsorption | suction position is set by calculating | requiring a specific angle. In the present embodiment, as described above, this optimum suction position is performed based on the pressure detection results of the detection points A and B described above. That is, as shown in FIG. 6B, the ball suction operation is actually performed on the candidate points P (i) determined in a lattice shape at a constant pitch, and the pressure detection results at the detection points A and B at this time are displayed on the display unit. 21 is displayed.
[0039]
Then, the operator confirms the display result visually, and determines whether or not the candidate point P (i) is the suction position by determining whether or not the differential pressure ΔP equal to or greater than the threshold value has been obtained. . Of course, the determination unit 20 may automatically determine the comparison with the threshold value of the differential pressure ΔP and display only the determination result on the display unit 21.
[0040]
In the above example, an example of determination based on the pressure difference ΔP between the detection points A and B is shown. However, as shown in FIGS. 4B and 5B, the pressure detection line L (A) Shows the pressure change corresponding to the suction pressure of the vacuum suction source 16 in any case, and the pressure detection result greatly differs depending on the presence or absence of the positional deviation. Only the pressure detection result, that is, the detection result of the pressure detecting means for detecting the pressure indicating the degree of vacuum in the internal space 7b of the alignment unit 5a may be displayed on the display unit 21 to make the above determination. In this case, whether the detection pressure at the detection point B is substantially equal to the atmospheric pressure regardless of the passage of time is a criterion for determining whether or not the suction position is appropriate.
[0041]
Next, the presence / absence determination of a suction error of the ball 6 during the ball suction operation by the suction head 13 will be described. As described above, in the ball suction, when the ball 6 is correctly sucked into each suction hole 13a of the suction head 13, a pressure detection result as shown in FIG. When the pressure detection result is obtained, it is determined that the ball 6 has been correctly sucked by the suction head 13 without any suction mistake. That is, the pressure detection result of the detection points A and B by the pressure detection unit 19 is compared with the same threshold value as in the case of the alignment of the suction position by the determination unit 20 to determine whether there is a suction error. The result is displayed on the display unit 21. Also in this case, the above determination may be made based only on the pressure detection result at the detection point B in the internal space 7b, as in the above-described determination of suitability for alignment.
[0042]
Here, there are two modes of the suction mistake of the suction head 13 depending on the cause of occurrence. Hereinafter, a description will be given with reference to FIGS. FIG. 7 shows a case where the alignment of the balls 6 in the alignment unit 5a is performed normally and a suction error occurs during the suction operation by the suction head 13. That is, as shown in FIG. 7 (a), all the concave portions 7 of the alignment portion 5a accommodate one ball 6 one by one, and when these balls 6 are sucked by the suction head 13, FIG. An adsorption error occurs in such a form that the ball 6 is not adsorbed at the position of the arrow * shown in b) and remains in the recess 7.
[0043]
Such a suction error occurs when the suction hole 13a and the recess 7 are misaligned. In a state where such a suction error has occurred, the suction head 13 and the internal space 7b of the alignment portion 5a partially communicate with each other through the suction hole 13a where the ball 6 is not sucked. Therefore, for the same reason as in the case shown in FIG. 5, the pressure detection results at the detection points A and B are similar to the pattern shown in FIG.
[0044]
At this time, the pressure detection result at the detection point B differs depending on the degree of the suction mistake. When a suction mistake occurs in most of the suction holes 13a, the pattern is almost the same as in FIG. When a suction error has occurred, a differential pressure ΔP corresponding to the degree of communication between the suction head 13 and the internal space 7b of the alignment portion 5a is indicated.
[0045]
Next, a description will be given of a case where a suction error occurs due to the incorrect alignment of the balls 6 in the alignment portion 5a. That is, as shown in FIG. 8A, among the concave portions 7 of the alignment portion 5a, the concave portions 7 indicated by the arrows * do not contain the balls 6 due to misalignment. When the suction head 13 is aligned with the alignment portion 5a in such a state and the suction operation is performed, a suction error in which the ball 6 does not exist occurs at the position of the arrow * shown in FIG. 8B.
[0046]
Such a suction error occurs regardless of the suction operation itself, such as alignment during the suction operation. Even in such a case, as in the case shown in FIG. 7, the suction head 13 and the internal space 7b of the alignment portion 5a partially communicate with each other. The pattern is the same as in the case of a mistake.
[0047]
That is, in either case of FIG. 7 or FIG. 8, if the ball 6 is not correctly adsorbed in any of the adsorption holes 13a after the adsorption error, that is, after the ball adsorption operation by the adsorption head 13, the pressure detection result is the same. This makes it possible to determine whether or not there is a suction mistake after the ball suction operation regardless of the cause.
[0048]
As described above, in the mounting of the conductive ball shown in the present embodiment, the pressure in the internal space 7b communicating with the first pressure detecting means for detecting the pressure in the suction head 13 and / or the concave portion 7 of the alignment portion 5a. Based on the detection result of the second pressure detecting means for detecting the suction, the adequacy determination of the suction position and the presence / absence determination of the suction mistake are performed. By adopting such a method, it is possible to accurately determine the adequacy of the alignment of the suction head, which is difficult to visually confirm, and also to determine whether there is a suction error. It has become.
[0049]
【The invention's effect】
According to the present invention, in the ball adsorbing operation for adsorbing the conductive balls from the alignment portion provided with a plurality of recesses capable of accommodating one conductive ball on the upper surface in a predetermined arrangement and having an internal space communicating with the recesses, Based on the detection results of the first pressure detection means and the second pressure detection means for detecting the first pressure in the suction head and the second pressure in the internal space of the alignment section, respectively, By determining whether or not the relative position is appropriate, it is possible to accurately determine the appropriateness of the relative position with respect to the alignment portion of the suction head and the presence or absence of a suction failure of the conductive ball by the suction head during the ball suction operation.
[Brief description of the drawings]
FIG. 1 is a perspective view of a conductive ball mounting device according to an embodiment of the present invention. FIG. 2 is a suction hole of a suction head and a recess of an alignment portion of the conductive ball mounting device according to an embodiment of the present invention. FIG. 3 is a block diagram showing the configuration of a vacuum suction system and a control system of a conductive ball mounting device according to an embodiment of the present invention. FIG. 4 is a block diagram of the conductive ball according to the embodiment of the present invention. FIG. 5 is an explanatory diagram of pressure change in the adsorption operation. FIG. 5 is an explanatory diagram of pressure change in the adsorption operation of the conductive ball according to the embodiment of the invention. FIG. FIG. 7 is an explanatory view of the alignment of the suction head and the alignment portion in FIG. 7. FIG. 7 is an explanatory view of a suction error in the suction operation of the conductive ball according to the embodiment of the invention. Explanatory drawing of adsorption mistake in ball adsorption operation Akira]
3 Substrate 5a Alignment part 6 Ball 7 Recess 7b Internal space 13 Adsorption head 13a Adsorption hole 19 Pressure detection part 20 Determination part 21 Display part A, B Detection point PS1, PS2 Pressure sensor

Claims (1)

A conductive ball mounting method for holding a conductive ball and mounting it at a predetermined position, wherein a plurality of concave portions capable of accommodating one conductive ball are provided in a predetermined arrangement on an upper surface and communicated with the concave portion In a ball adsorbing operation in which the conductive balls accommodated in the respective concave portions of the aligning portion are vacuum adsorbed by an adsorbing head having an adsorbing hole corresponding to the arrangement, the first pressure in the adsorbing head and the The suitability of the relative position of the suction head with respect to the alignment portion is determined based on the detection results of the first pressure detection means and the second pressure detection means for detecting the second pressure in the internal space of the alignment portion, respectively. And mounting method of conductive balls.

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