JP4187873B2 - Flux supply device for conductive ball mounting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention aligns and mounts solder balls on a package using conductive balls (hereinafter referred to as solder balls) as connecting materials to a mounting substrate such as BGA (Ball Grid Array), CSP (Chip Size Package) or Chip Scale Package (CSP). The present invention relates to a solder ball mounting apparatus.
[0002]
[Prior art]
For example, a solder ball mounting apparatus shown in FIG. 14 has been proposed. In this solder ball mounting device, a plurality of solder balls 2 stored in a container 1 are agitated to a predetermined thickness in a solder ball supply section A in which a compressed gas is blown up and floated, and in a flux tank 3. A plurality of adsorptions in the same arrangement as the arrangement of the flux supply section B for supplying the flux 4, the mounting section C for positioning the package 5 on which the solder balls 2 are to be mounted, and the connection terminals for mounting the solder balls 1 of the package 5 An alignment mask 6 in which holes 6a are formed and connected to a vacuum source 8 via a pipe 7, and a transfer device D that sequentially moves the alignment mask 6 in the order of the ball supply unit A, the flux supply unit B, and the mounting unit C. And.
[0003]
As shown in FIG. 15, while the alignment mask 6 is positioned on the ball supply unit A by the transfer device D, vacuum pressure is supplied to the alignment mask 6 from the vacuum source 8 through the pipe 7, and from the bottom of the container 1. The compressed gas is blown out, and the solder balls 2 inside are blown up and floated toward the alignment mask 6, and the solder balls 2 are adsorbed in the suction holes 6 a of the alignment mask 6.
[0004]
When a predetermined number of solder balls 2 are attracted to the alignment mask 6, the transfer device D moves the alignment mask 6 above the flux supply unit B as shown in FIG. 16, and then as shown in FIG. 17. Then, the alignment mask 6 is lowered, the lower end portion of the solder ball 2 adsorbed on the alignment mask 6 is immersed in the flux 4, and the flux 4 is applied to the solder ball 2.
[0005]
When the flux 4 is applied to the solder balls 2, the transfer device D causes the alignment mask 6 to be positioned above the mounting portion C and the solder balls 2 to face the connection terminals 5a of the package 5 as shown in FIG. After the movement, the solder ball 2 is pressed against the connection terminal of the package 5. Then, the vacuum pressure supplied to the alignment mask 6 is cut off, the solder balls 2 are released from the alignment mask 6, and the solder balls 2 are mounted on the package 5. At this time, as shown in FIG. 19, the solder balls 2 are held on the connection terminals 5 a of the package 5 by the adhesive force of the flux 4.
[0006]
By heating (reflowing) the package 5 holding the solder balls 2, the solder balls 2 are melted, and, for example, 100 to 300 solder bumps (connection protrusions) are formed at a time.
[0007]
Further, as another solder ball mounting method, as shown in FIG. 20, a transfer jig 10 having a plurality of transfer pins 9 in the same arrangement as the connection terminals of the package was used, and the solder balls were scraped in advance in the flux tank 3. The flux 4 is taken out at the tip of the transfer pin 9, and the flux adhering to the tip of the transfer pin is transferred to the connection terminal 5a of the package 5 as shown in FIG. 21, and then the alignment mask as shown in FIG. In some cases, the solder balls 2 adsorbed by the solder 6 are mounted.
[0008]
In each solder ball mounting step, when flux is applied to the solder balls, there are a method of supplying the flux by bringing the solder balls into contact with the bottom surface of the flux tank and a method of supplying the solder balls without contacting them. Even so, it is required to supply an appropriate amount of flux to the solder balls.
[0009]
[Problems to be solved by the invention]
For example, when a gel-like flux is used, the viscosity of the flux decreases for a certain period from the start of use, and then the viscosity tends to increase. Since the surface tension of the flux changes as the flux viscosity changes, the flux 4 is scraped and averaged with the squeegee 9 set at a predetermined distance H from the bottom surface of the flux tank 3 as shown in FIG. However, the film thickness T of the flux 4 varies.
[0010]
If the film thickness T of the scraped and averaged flux varies, the amount of the flux 4 supplied to the solder balls 2 varies even when the solder balls 2 are brought into contact with the bottom surface of the flux tank 3 as shown in FIG. Become. In addition, as shown in FIG. 25, when the solder ball 2 is not brought into contact with the bottom surface of the flux tank 3, the flux 4 may not be supplied to the solder ball 2.
[0011]
If the amount of flux adhering to the solder balls is small, not only the solder ball holding force due to the adhesive force of the flux will be reduced when mounted on the package, the solder ball holding becomes unstable, but also the solder surface in the reflow process Incomplete removal of oxides causes poor soldering. Further, if the amount of flux attached to the solder balls is increased, it may cause defects such as the flux that cannot be completely removed in the cleaning process after reflow.
[0012]
In view of the above circumstances, an object of the present invention is to provide a flux supply device in a solder ball mounting device that can detect the surface position of a flux and always supply a constant amount of flux.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention according to claim 1 of the present application, after adsorbing the conductive balls with an alignment mask in which holes for adsorption are formed in the same arrangement as the connection terminals formed in the package, In the flux supply device in the conductive ball mounting device in which the conductive balls are mounted on the connection terminals of the package by the adhesive force of the flux, the flux bath containing the gel-like flux, and moving along the flux bath A squeegee for forming a flux film having a predetermined thickness and a sensor for detecting the thickness of the flux film are provided at a predetermined distance from the surface of the flux film formed in the flux tank.
[0014]
According to the second aspect of the present invention, after the conductive balls are adsorbed by an alignment mask having the same arrangement as the connection terminals formed on the package and the holes for adsorption are formed, the conductive balls are attracted by the adhesive force of the flux. In the flux supply device in the conductive ball mounting device mounted on the connection terminal of the package, the flux tank accommodating the gel-like flux and the gap between the flux tank are arranged to be adjustable at a predetermined interval. A pair of squeegees that move along the flux tank to form a flux film having a predetermined thickness, and are arranged at a predetermined distance from the surface of the flux film formed in the flux tank, A sensor for detection was provided.
[0015]
Furthermore, the invention according to claim 3 is the invention according to claim 1 or claim 2, wherein both ends of the flux film forming region of the flux tank are lowered by a step larger than the diameter of the conductive ball. The step portion is formed, and the connection surface between the flux film forming region and the step portion is formed by an inclined surface that penetrates below the flux film forming region.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 12 show a first embodiment of the present invention. FIG. 1 is a side view of a flux coating apparatus according to the present invention, FIG. 2 is a view taken in the direction of arrow A in FIG. 1 is a plan view showing the relationship between the flux tank, the squeegee and the sensor, FIG. 5 is a front sectional view of the flux tank, and FIG. 6 is an enlarged view showing the step portion of the flux tank. FIG. 7 is a plan view showing an example of a flux surface detection path by the sensor, FIG. 8 is a front view showing a detection state of the flux surface by the sensor, and FIG. 9 is a control for controlling the thickness of the flux film. System diagram, FIG. 10 is an explanatory diagram showing the detection method by the sensor and its output, FIG. 11 shows an example of an abnormality occurring on the surface of the scraped and averaged flux, (a) is a plan view, and (b) is a plan view. Enlarged view, Fig. 12 is a characteristic diagram showing an example of output from the sensor A.
[0017]
1 to 4, reference numeral 21 denotes a base plate. Reference numeral 22 denotes a support, which is erected on the base plate 21 at a predetermined interval. A flux base 23 is fixed to the support 22. A flux tank 24 is fixed to the flux base 23. A bracket 25 is fixed to the base plate 21 in parallel with the flux tank 24.
[0018]
Reference numeral 26 denotes a rail of the linear guide device, which is fixed to the bracket 25. Reference numeral 27 denotes a bearing of a linear guide device, which is slidably supported on the rail 26. A feed screw 28 is rotatably supported by the bracket 25 via a pair of bearings 29 in parallel with the rail 26. A motor 30 is fixed to the bracket 25 via a bracket 31 and is coupled to the feed screw 28 via a joint 32.
[0019]
A slider 33 is formed with a nut into which the feed screw 28 is screwed, and is fixed to the bearing 27. A plate 34 is fixed to the upper end of the slider 33.
[0020]
Reference numeral 35 denotes a rail of the linear guide means, which is fixed to the plate 34. Reference numeral 36 denotes a bearing of linear guide means, which is slidably fixed to the rail 35. A motor 37 is fixed to the slider 33 via a bracket 38. A feed screw 39 is coupled to the motor 37 via a joint 40.
[0021]
A slider 41 is formed with a nut to which the feed screw 39 is screwed, and is fixed to the bearing 36. A mounting plate 42 is fixed to one end of the slider 41. A sensor 43 is fixed to the mounting plate 42 so as to face the flux tank 24.
[0022]
Reference numeral 44 denotes a rail of the linear guide device, which is fixed to the bracket 25. Reference numeral 45 denotes a bearing of a linear guide device, which is slidably supported on the rail 44. A feed screw 46 is rotatably supported by the bracket 25 via a pair of bearings 47 in parallel with the rail 44. A motor 48 is fixed to the bracket 25 via a bracket 49 and is connected to the feed screw 46 via a joint 50.
[0023]
A slider 51 is formed with a nut screwed with the feed screw 46 and fixed to the bearing 45.
[0024]
Reference numeral 52 denotes a rail of the linear guide device, which is fixed to the slider 51. 53 is a bearing of the linear guide device, and is slidably supported on the rail 52. A motor 54 is fixed to the upper end of the slider 51 via a bracket 55. A feed screw 56 is coupled to the motor 54.
[0025]
A slider 57 is formed with a nut screwed to the feed screw 56 and is fixed to the bearing 53. 58 and 59 are air cylinders, which are fixed to the slider 57 at predetermined intervals. Reference numerals 60 and 61 denote squeegees, which are fixed to air cylinders 58 and 59, respectively.
[0026]
5 and 6, the slack tank 24 is formed with step portions 24A having a height larger than the diameter of the solder balls 2 at both ends of a region where a flux film having a predetermined thickness is formed. The flux film forming region and the stepped portion 24A are connected by the inclined surface 24B so that, for example, the solder ball 2 pushed by the squeegee 61 enters below the flux film forming region.
[0027]
By the operation of the motors 30 and 37, the sensor 43 scans the flux film formation region of the flux tank 24 and measures the thickness of the flux film, as shown in FIGS.
[0028]
In FIG. 9, 62 is an adder that compares a preset film thickness of the flux with the output of the amplifier 67 that amplifies the output of the sensor 43, and outputs the difference. Reference numeral 63 denotes a control device, which is based on the output of the adder 62, a controller 64 for determining the moving direction and amount of movement of the squeegee, a speed control system 65 for controlling the moving speed based on the command of the controller 64, and the position. A position control system 66 for controlling is provided, and the motor 54 is driven to control the positions of the squeegees 60 and 61.
[0029]
FIG. 10 shows a sensor 43 using a semiconductor laser. The laser beam oscillated from the semiconductor laser 43A is irradiated onto the surface of the flux 4 by the lens 43B, and the reflected light is condensed on the photoelectric conversion element 43D by the lens 43C. It is configured to let you. At this time, the position of the surface of the flux 4 is detected from the height of the surface of the flux 4 as shown in FIG.
[0030]
With such a configuration, in a state where the squeegees 60 and 61 are above the stepped portion 24A of the flux tank 24, the motor 54 is operated and the slider 57 is moved to move the squeegees 60 and 61 from the bottom surface of the flux tank 24 in advance. Move to the set height position.
[0031]
As shown in FIG. 3, the cylinder 59 is actuated to raise the squeegee 61 forward in the moving direction of the slider 51, and then the motor 48 is actuated to move the slider 51 to the motor 48 side. Then, the flux 4 in the flux tank 24 is scraped and averaged by the squeegee 60.
[0032]
In this state, the motors 30 and 37 are operated, the sensor 43 is moved as shown in FIG. 7, and the height of the surface of the flux 4, that is, the film thickness of the flux 4 is measured. As a result of the measurement, if the film thickness of the flux 4 is within an allowable range, the flux 4 is supplied to the solder balls.
[0033]
If the film thickness of the flux 4 is outside the allowable range, the control unit 63 to which the measurement result is fed back controls the motor 54 to scrape the flux 4 again and measure the film thickness of the flux again. Repeatedly, the film thickness of the flux 4 is controlled within an allowable value.
[0034]
When the flux 4 is scraped and averaged with the squeegees 60 and 61, if a relatively large foreign matter (for example, a solder ball dropped from the alignment mask) is dropped on the flux 4, as shown in FIG. 11 on the surface of the flux 4. 4A may be generated. Such a groove 4A is detected by a sensor 43 as shown in FIG. Accordingly, when the output of the sensor 43 exceeds the allowable deviation even at one point, the flux can be uniformly supplied to the solder balls by scraping the flux 4 again.
[0035]
As shown in FIGS. 5 and 6, the foreign matter that has moved to the stepped portion 24 </ b> A of the flux tank 24 together with the flux 4 is pushed obliquely downward by the inclined surface formed on the front surface in the moving direction of the squeegees 60 and 61. When the squeegees 61 and 60 move in the opposite direction, the foreign matter is captured by the inclined surface 24B of the flux tank 24 and sinks toward the bottom of the stepped portion 24A. .
[0036]
As described above, the position of the surface of the flux 4 is detected, and the flux 4 is supplied to the solder ball only when the height of the surface of the flux 4 is within the allowable range. An amount of flux can be supplied.
[0037]
FIG. 13 shows another embodiment of the sensor used in the present invention, in which (a) is a front sectional view of the sensor and (b) is a characteristic diagram of its output.
[0038]
In the figure, 70 is an air nozzle. Reference numeral 71 denotes a pressure sensor that measures the pressure in the air nozzle 70.
[0039]
With such a configuration, when the outlet of the air nozzle 70 is brought close to the surface of the flux 4, the pressure in the air nozzle 70 changes corresponding to the distance. This change in pressure is represented by (b), where S is the distance between the air nozzle 70 outlet and the flux 4, and the distance between the tip of the air nozzle 70 and the surface of the flux 4 can be detected.
[0040]
In the above embodiment, the sensor 43 is moved with respect to the flux tank. However, the sensor 43 may be fixed and the surface position of the flux may be detected only at one point.
[0041]
【The invention's effect】
As described above, according to the present invention, the height of the flux surface scraped with the squeegee is detected, and the flux is supplied when the height of the flux surface is within an allowable range. A certain amount of flux can be supplied to the solder balls.
[0042]
Moreover, the foreign material mixed in the flux can be detected. Furthermore, foreign matter mixed in the flux can be removed from the flux film formation area and submerged in the stepped part of the flux tank, so that it is possible to prevent the occurrence of poor soldering and poor cleaning. easy explanation】
FIG. 1 is a side view of a flux application device according to the present invention.
FIG. 2 is a view taken in the direction of arrow A in FIG.
FIG. 3 is a view taken in the direction of arrow B in FIG.
FIG. 4 is a plan view showing the relationship between a flux tank, a squeegee, and a sensor.
FIG. 5 is a front sectional view of a flux tank.
FIG. 6 is an enlarged view showing a step portion of the flux tank.
FIG. 7 is a plan view showing an example of a flux surface detection path by a sensor.
FIG. 8 is a front view showing a detection state of a flux surface by a sensor.
FIG. 9 is a control system diagram for controlling the thickness of the flux film.
FIG. 10 is an explanatory diagram showing a detection method by a sensor and its output.
FIGS. 11A and 11B show an example of an abnormality that occurs on the surface of the scraped and averaged flux, where FIG. 11A is a plan view and FIG. 11B is an enlarged view;
FIG. 12 is a characteristic diagram showing an example of output from a sensor.
13A and 13B show another embodiment of the sensor used in the present invention, in which FIG. 13A is a front sectional view of the sensor, and FIG. 13B is a characteristic diagram of its output.
FIG. 14 is a configuration diagram showing an example of a solder ball mounting apparatus to which the present invention is applied.
FIG. 15 is a process diagram showing a solder ball adsorption process;
FIG. 16 is a process diagram showing a flux application process.
FIG. 17 is a process diagram showing a flux application process.
FIG. 18 is a process diagram showing a mounting process.
FIG. 19 is an enlarged view showing a state in which solder balls are mounted on the package.
FIG. 20 is a process diagram showing a flux supply process in another solder ball mounting method.
FIG. 21 is a process diagram showing a flux supply process in another solder ball mounting method;
FIG. 22 is a process diagram showing a solder ball mounting process in another solder ball mounting method;
FIG. 23 is an enlarged view showing the state of flux scraping in the flux loading process.
FIG. 24 is an enlarged view showing a problem in a flux application process.
FIG. 25 is an enlarged view showing a problem in the flux application process.
[Explanation of symbols]
2 ... solder balls, 4 ... flux, 5 ... package, 5a ... connection terminals,
6 ... Alignment mask, 6a ... Hole, 24 ... Flux tank, 43 ... Sensor,
60, 61 ... Squeegee.

Claims (2)

After adsorbing the conductive balls with an alignment mask in which holes for adsorption are formed in the same arrangement as the connection terminals formed on the package, the conductive balls are mounted on the connection terminals of the package by the adhesive force of the flux. A flux supply device in a conductive ball mounting device , which is formed in a flux tank that contains a gel-like flux, a squeegee that moves along the flux tank to form a flux film of a predetermined thickness, and the flux tank In the flux supply device in the conductive ball mounting device provided with a sensor for detecting the thickness of the flux film, which is arranged at a predetermined interval from the surface of the flux film formed ,
At both ends of the flux film forming region of the flux tank, a stepped portion that is lower by at least a step larger than the diameter of the conductive ball is formed, and a connection surface between the flux film forming region and the stepped portion is the flux film forming region. A flux supply device in a conductive ball mounting device, wherein the flux supply device is formed with an inclined surface that penetrates downward. After adsorbing the conductive balls with an alignment mask in which holes for adsorption are formed in the same arrangement as the connection terminals formed on the package, the conductive balls are mounted on the connection terminals of the package by the adhesive force of the flux. met flux supply device in the conductive ball mounting apparatus, and a flux bath containing a gel-like flux, at predetermined intervals, said adjustably position the distance between the flux bath, move respectively along the flux tank A pair of squeegees that form a flux film of a predetermined thickness, and a conductive sensor that is disposed at a predetermined distance from the surface of the flux film formed in the flux tank and detects the thickness of the flux film. In the flux supply device in the ball mounting device ,
At both ends of the flux film forming region of the flux tank, a stepped portion that is lower by at least a step larger than the diameter of the conductive ball is formed, and a connection surface between the flux film forming region and the stepped portion is the flux film forming region. A flux supply device in a conductive ball mounting device, wherein the flux supply device is formed with an inclined surface that penetrates downward.

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