JPH10290068A - Method and equipment for forming solder bump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a solder bump at one time with a suitable amount of solder with high workability without heating it in a reflow oven. SOLUTION: The edge face 21a of a punch 21 inserted into a through-hole 22c provided to a side 22 is retracted from the edge face 22a of the die 22 by a required distance to provide a recess 22b which is as large in volume as required to the edge face 22a of the die 22. Then, solder paste 23 is filled into the recess 22b. Thereafter, the punch 21 is moved to the edge face 22a of the die 22 to extrude the solder paste 23 from the recess 22b. The solder paste 23 extruded by the movement of the punch 221 is melted. Thereafter, the solder paste 23 extruded by the edge face 21a of the punch 21 is brought into contact with a copper pad 25 located on a board 24 and melted into a solder bump 27.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for forming solder bumps for mounting an IC chip or the like on a printed circuit board or the like.

[0002]

2. Description of the Related Art When an IC chip or the like is mounted on a printed circuit board, it is necessary to form solder bumps on the board for electrically contacting the printed circuit with the IC chip or the like and fixing them. In recent years, the mounting density on a substrate has increased, the number of solder bumps has increased, and the arrangement pitch of the solder bumps has become narrower.

Conventionally, as a method of forming solder bumps, for example, a method shown in FIG. 19 has been used. That is, the copper pad 11 is formed on the substrate 10 in advance (FIG. 19).
(A)). Next, the solder paste 12 is printed (FIG. 19).
(B)), a heating reaction is performed in a reflow furnace. Thereafter, the solder paste 12 other than the copper pads 11 is removed by washing, and the solder bumps 13 are collectively formed on the many copper pads 11 (FIG. 19C).

As another method for forming solder bumps, there is a method shown in FIGS. 20 (a) and 20 (b). That is, the solder discharge device 14 having a structure like a syringe is connected to the cylinder portion 19.
Heated by the heater 15 built in the cylinder unit 1
9 is melted (FIG. 20 (a)), and the pressure is controlled by the piston 16 so that the melted solder 17 passes through the minute hole 18
A small amount of liquid is ejected from the substrate and adheres to the copper pad 11 (FIG. 2)
0 (b)).

[0005]

However, the conventional solder bump forming method has the following problems.
That is, 1) In the first method, it may be difficult to attach a required amount of solder to the substrate by only one cycle of the process. .

In this method, when some of the solder bumps are defective (the proper amount of solder has not been reached), if the arrangement pitch of the bumps is narrow, only these defective solder bumps are used. It is difficult to print with additional solder paste to increase the amount of adhered solder to an appropriate amount. In this case, a mask for printing by adding a solder paste can be created and additional printing can be performed, but this causes an excessive increase in cost.

[0007] 2) In the second method, when the discharged molten solder adheres to the copper pad, the molten solder runs out of liquid in the cylinder portion, and the position at which the liquid runs out varies, so that a small amount and a fixed amount of solder can be used. It is difficult to supply it stably.

The surface of a copper pad to which solder is to be attached or a defective solder bump already existing is oxidized, and in many cases, molten solder is difficult to adhere to this surface. For this reason, when attaching solder, there is a trouble that a flux or the like is separately applied as a reducing agent.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems. According to the first aspect of the present invention, an end face of a punch inserted into a through hole provided in a die is replaced with a die end face. A step of providing a recess of a desired volume on the die end face, drawing the solder paste into the recess, extruding the solder paste by moving the punch toward the die end face, A method of forming a solder bump, comprising a step of melting a solder paste extruded by movement of a punch.

According to a second aspect of the present invention, in the first aspect of the invention, the punch comprises an optical fiber;
A solder bump forming method, wherein the solder paste is melted by heating light passing through the optical fiber.
A third aspect of the present invention is the solder bump forming method according to the first aspect of the present invention, further comprising a step of cleaning the punch before the step of embedding the solder paste.

[0011] Further, the invention according to claim 4 is the invention according to claim 1.
In the invention described in the above, there is provided a method for forming a solder bump, wherein a step of scraping off the solder paste is provided on an end surface of the die in which the solder paste is embedded. Further, the invention described in claim 5 provides the invention according to claims 1 to 4
An apparatus for implementing the method of forming a solder bump according to claim 1, wherein a die provided with a through-hole, a punch slidably inserted into the through-hole, and a solder paste formed in a depression formed by the through-hole and the punch. Embedding means, means for sliding the punch in the through-hole of the die to extrude the solder paste to the end face of the die, and a heating source for melting the solder paste. is there.

In this apparatus, it is preferable that the die is a ferrule and the punch is an optical fiber.
Further, it is preferable to provide a cleaning means for cleaning a tip of the ferrule in which the solder paste is embedded. Here, according to the first aspect of the present invention, since the end face of the punch can be retracted by a desired distance from the end face of the die and a recess having a desired volume can be provided on the end face of the die, the solder paste is embedded in this recess. Thereby, a fixed amount of solder paste having the same volume as the volume of the depression can be stably supplied. Therefore, when the volume of the depression is set to be an appropriate volume of the solder bump, an appropriate amount of the solder bump can be formed at a time.

Further, when a solder paste extruded by a punch projecting from an end face of a die is melted and a solder bump is formed on a substrate, a die is formed at a position where a solder bump is to be formed (for example, a copper pad or a defective solder bump). When the solder paste embedded in the end face is extruded with a punch and brought into contact, and then heated and melted, the flux (reducing agent) contained in the solder paste acts to remove the surface oxide film of the copper pad or defective solder bump. Therefore, there is no need to separately supply a flux, and workability is improved.

Further, since the solder paste is extruded from the dent of the die by the punch, the solder separation is improved compared to the method of embedding the solder paste in a metal mask having a group of holes. Further, the desired amount of the solder bumps can be easily changed by changing the distance at which the end face of the punch is drawn in from the end face of the die. When using a metal mask having a group of holes, it is necessary to change the metal mask when changing the amount of solder bumps, and when punching a solder foil with a punch, changing the thickness of the solder foil It is not easy to change the amount of solder bumps.

In the second aspect of the present invention, the optical fiber is used as the punch. However, since the optical fiber has a good outer diameter accuracy and is easily available, the punch can be easily prepared. In addition, since the solder paste attached to the end face of the optical fiber is melted by the heating light transmitted through the optical fiber, the heating area can be localized at a necessary place, so when forming a solder bump in a narrow area, It does not affect other peripheral solder bumps.

Furthermore, when the optical fiber is made of glass,
Since the solder wettability of the end face of the optical fiber is lower than that of the copper pad on which the solder bump should be formed or the defective solder pad, the solder paste can be easily transferred from the optical fiber to the copper pad or the defective solder pad. Workability is improved. Also,
According to the third aspect of the present invention, since the punch is washed before embedding the solder paste, the solder paste can be appropriately embedded in the depression formed in the punch, and the amount of the solder paste can be accurately controlled. it can.

Further, in the invention according to claim 4, since the excess solder paste is wiped off from the end face of the ferrule by scraping off, when transferring a copper pad or a defective solder pad solder paste, excess solder paste adhered to the ferrule end face is removed. It can be prevented from being disturbed by a solder paste. Further, the amount of the solder paste becomes more accurate. Further, the invention of claim 5 is an apparatus for achieving the invention of claims 1 to 4, comprising a die provided with a through hole, and a punch slidably inserted into the through hole. This is a device capable of supplying a desired amount of solder paste by a simple operation of merely embedding solder paste in a depression formed by a die and a punch.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. (Embodiment 1) FIGS. 1A to 1E are explanatory diagrams of an embodiment of the present invention. The present embodiment is a solder bump forming method for efficiently forming a desired amount of solder bumps on a copper pad using a solder bump forming apparatus. The method is as follows. 1) First, as shown in FIG.
One end of a punch 21 having a small sectional area S of about 3 mm is fixed to the holder 20, and the other end of the punch 21 is
Is slidably inserted into the through hole 22c. Holder 2
Numeral 0 is relatively movable with respect to the die 22 in the longitudinal direction of the punch 21 by operating means (not shown).

2) Then, the holder 20 is moved,
The end face 21a of the punch 21 is retracted from the end face 22a of the die 22 by a distance D. Therefore, a depression 22b having a volume V (= SD) is opened in the end face 22a. The volume V of the recess 22b is made equal to the volume of the solder bump to be formed. Thereafter, the solder paste 23 is embedded in the recess 22b by embedding means (not shown) such as squeezing (FIG. 1B). At this time, the solder paste 23a may adhere to the end face 22a.

3) Next, the solder paste 23a attached on the end face 22a of the die 22 is scraped off, and the volume of the solder paste 23 is set to a desired value V (FIG. 1 (c)). 4) Next, the punch 21 is pressed so that the end face 21a protrudes from the end face 22a of the die 22, and the solder paste 23 is brought into contact with the copper pad 25 on the substrate 24 on which the solder bump is formed. Thereafter, the solder paste 2 is irradiated by a non-contact light heating source 26 such as a laser light source or a halogen lamp.
3 is heated and melted (FIG. 1 (d)). Then, since the solder paste 23 contains the flux, it is adapted to the copper pad 25 and the solder bump 27 is formed.
(E)).

(Embodiment 2) In the present embodiment, FIG.
As shown in FIG. 7, an optical fiber 28 is used as a punch. The optical fiber 28 is held by the holder 20, and one end is slidably inserted into the through hole 22 c of the die 22. At the end face 28a of the optical fiber 28,
As in the first embodiment, a desired volume of the solder paste 23 is extruded, and then the solder paste 23 is brought into contact with a copper pad 25 on a substrate 24 on which a solder bump is to be formed (FIG. 2).
(B)) Heat and melt to form solder bumps 27 (FIG. 2 (c)). The heating of the solder paste 23 is performed by passing heating light from an optical heating source 26 through an optical fiber 28. As the light heating source 26, a semiconductor laser device, a halogen lamp, a xenon lamp, or the like can be used.

As shown in FIG. 2D, when the solder bumps 27 are formed, the solder paste 23 is heated in a state where the solder paste 23 is not in contact with the copper pads 25 on the substrate 24 on which the solder bumps are formed. After the balls 23b are formed, the solder balls 23b may be transferred to the copper pads 25 to form the solder bumps 27. (Embodiment 3) Next, a third embodiment of the solder bump forming apparatus will be described in detail with reference to FIGS.

As shown in FIGS. 3 to 6, a solder bump forming apparatus (hereinafter simply referred to as a “bump forming apparatus”) 1
An X-axis robot 3, two Y-axis robots 4, a conveyor 5, a preheating unit 6, a head unit 7, and a supply unit 8 are provided in the housing 2, and the operation is controlled by a controller 9 such as a programmable computer according to a preset operation flow. Is done. A monitor 2a is installed on the upper part of the housing 2.

Each of the X-axis robot 3 and the Y-axis robot 4 uses a ball screw. X axis robot 3
Are arranged in parallel with the conveying direction of the conveyor 5, and two Y
The axis robot 4 is arranged in a direction perpendicular to the direction of transport of the conveyor 5. Then, the X-axis robot 3 has two Y
The head unit 7 is supported movably in the axial direction while being supported by the axis robot 4, and is moved by the Y-axis robot 4 in a direction orthogonal to the transport direction of the conveyor 5. Therefore, in the following description, the direction of conveyance of the conveyor 5, the direction of the axis of the X-axis robot 3 is the X-axis direction, the direction perpendicular to the direction of conveyance of the conveyor 5, and the direction of the axis of the Y-axis robot 4 is the Y-axis. Called direction.

The conveyor 5 conveys a printed circuit board (hereinafter simply referred to as a “substrate”) S, which is carried in from a carry-in port (not shown) provided on the right side of the housing 2, to the preheating unit 6,
Here, as described later, the substrate S on which the solder bumps are formed at desired positions is carried out to a carry-out port (not shown) provided on the left side of the housing 2. The preheating section 6 is a section for preheating the conveyed substrate S for a predetermined time, and is arranged at a lower portion in the middle of the conveyor 5 in the X-axis direction. A preheating plate 6a having a built-in heater is arranged to be able to move up and down. Here, the heating temperature of the substrate S is preferably as high as possible within a range where problems such as oxidation do not occur in the substrate S, for example, a temperature of less than 100 ° C. As the solder, a solder paste, for example, a micro solder manufactured by Harima Chemicals, Inc. is used. This solder paste has a particle size of 1
It is made by mixing and dispersing 5 to 30 μm solder particles in a paste, and has a strong activity and a melting point of 183 ° C. When using this solder paste, the temperature of the substrate S should be 80-100
It is good to preheat to ℃.

The head unit 7 is a unit for attaching solder to a desired position on the substrate S, for example, on a copper pad.
It is attached to the axis of the axis robot 3 so as to be movable in the axial direction. The head unit 7 has a main body 71, a moving unit 72, and a sensor 73, as shown in FIGS. The main body 71 is a portion for attaching the solder supplied to the distal end of the optical fiber 714 described later by the supply unit 8 to the substrate S, and includes a lifting plate 711, a first lifting stage 712, a ferrule 713, and an optical fiber 714. I have.

The elevating plate 711 is vertically movably attached to a guide member 723, described later, of the moving unit 72 via a slider 715, and a constant tension spring 724 connected to the upper portion applies a predetermined spring force to the moving unit 72. It is elastically supported. The elevating plate 711 is a vertically long holding member that holds the ferrule 713 and the optical fiber 714, and has a horizontally extending arm 711a formed below. On the side of the lifting plate 711,
As shown in FIGS. 5 and 6, an upper stopper 711b and a lower stopper 711c using a screw that cooperates with a support arm 726 described later to regulate a relative vertical position between the moving unit 72 and the main body 71. Installed.

The first elevating stage 712 is a stage using a feed screw, and has a support plate 712a attached to the elevating plate 711, a main body 712b, a screw shaft 712c, and a slider 712d which moves in the vertical direction. The ferrule 713 is a single-core ferrule screwed into a mounting hole formed at the tip of the arm 711a, and functions as a die. Optical fiber 714
Is fixed to a fixed plate 716 attached to the slider 712d at a position slightly away from the tip by a pressing plate 717, and the tip extending downward is inserted into the fiber hole of the ferrule 713 so as to be freely retractable. Optical fiber 714, ferrule 713
It is fixed to the fixing plate 716 by appropriately adjusting the amount of insertion into the fiber hole. The optical fiber 714 sets the desired amount of solder embedded in the space formed by the fiber hole and the optical fiber 714 by appropriately adjusting the insertion amount of the ferrule 713 into the fiber hole by the first lifting stage 712. be able to. On the other hand, the other end of the optical fiber 714 is wound around a winding frame 728a (see FIGS. 8 and 9) of the moving section 72, which will be described later, is subjected to extra length processing, and is then connected to a laser diode module 725 (see FIG. 9). I have.

The moving section 72 is configured to movably support the lifting plate 711 in a direction approaching the substrate S and to be movable in a direction approaching the substrate S. The base 721, the second lifting stage 722, and the guide member 723, a winding frame 728a, and a laser diode (hereinafter simply referred to as “LD”) module 725
have. The base 721 is attached to the axis of the X-axis robot 3 so as to be movable in the axial direction, and a constant tension spring 724 is attached to the upper part. The base 721 is shown in FIGS.
As shown in FIG. 7, a photo sensor 721a for detecting that the head unit 7 is at the raised position is attached to the side. The second elevating stage 722 is configured in the same manner as the first elevating stage 712, and has a support plate 722 attached to the base 721.
a, a main body 722b, a screw shaft 722c, and a slider 722d that moves up and down.

The guide member 723 is attached to the slider 722d as shown in FIGS.
The movement of the slider 715 provided in the vertical direction is guided by two guide rails 723a (see FIG. 8). A detection piece 723b (see FIG. 8) for detecting that the head unit 7 is at the ascending position in cooperation with a photo sensor 721a provided on the base 721 is attached to a side portion of the guide member 723. Here, as shown in FIGS. 6 and 8, a support arm 726 that supports a sensor 73 described later is attached to the guide member 723.

As shown in FIG. 6, a tension spring 727 is provided between the support arm 726 and the arm 711a of the elevating plate 711. Therefore, the elevating plate 711 is vertically movably attached to the guide member 723 via the slider 715, but is supported by the moving portion 72 with a predetermined spring force by the constant tension spring 724 and the extension spring 727. . This spring force is about several grams to several tens of grams, at which the solder acting on the solder from the optical fiber 714 is not excessively crushed by the force acting on the solder from the optical fiber 714 when the solder attached to the tip of the optical fiber 714 is applied to a desired position on the substrate S. The value is set so that the main body 71 can move upward.

The winding frame 728a is, as shown in FIGS.
A cylindrical member attached to an attachment plate 728 provided on the side surface of the base 721. The center member presses the side surface of the elevating plate 711 and rattles the main body portion 71 and the moving portion 72 as the head unit 7 moves. The cylinder 729 which suppresses is installed. On the other hand, the LD module 725, as shown in FIG.
It is provided above the mounting plate 728, emits heating light to the optical fiber 714, and melts the solder supplied from the supply unit 8. At this time, it is preferable that the heating light has a wavelength in the range of 800 to 1000 nm when the micro solder is used as the solder.

The sensor 73 is a contact-type displacement sensor that is supported by a support arm 726 provided on the moving unit 72 and detects the relative distance between the elevating plate 711 and the moving unit 72. The sensor 73 includes a body 73a fixed to the support arm 726, and a lower end of a rod 73b extending downward from the body 73a.
A contact 73c that is in contact with the upper surface of the arm 711a of the elevating plate 711 is attached. Here, the sensor 73 is connected to the controller 9 of the housing 2 via a cord (not shown) connected to the upper connector 73d, and controls the relative distance between the arm 711a and the substrate S with high accuracy. However, in the present embodiment, a contact type displacement sensor is used as the sensor 73, but a non-contact type sensor such as a laser displacement meter may be used.

The supply unit 8 is shown in FIGS.
As shown in (a), it is arranged at the back right of the housing 2. The supply unit 8 is a unit for supplying solder to the main body 71 of the head unit 7, and is disposed on a base 80 provided in the housing 2 as shown in FIGS. , A cutting section 83, a monitor section 84, and a moving stage 85.

The cleaning section 81 is for cleaning the tip of the ferrule 713 and the optical fiber 714 to which the solder is supplied.
As shown in FIG. 1, the moving stage 85 is disposed between the embedding portion 82 and the cutting portion 83. The cleaning unit 81 is configured as shown in FIG.
As shown in the figure, a head unit 7 is provided above the cylindrical member.
An opening 81a through which a ferrule 713 attached to the arm 711a is inserted is formed, and an air nozzle 811 is provided at an upper portion, and an injection nozzle 812 is provided inside. The air nozzle 811 jets pressurized air sent from a factory air supply source toward the tip of the ferrule 713. On the other hand, the jet nozzle 812 jets a cleaning liquid, for example, alcohol, sent from the cleaning liquid tank 86 provided on the base 80 toward the tip of the ferrule 713. Here, the injection nozzle 812
Is ejected from the suction port (not shown) provided at the lower portion of the cleaning unit 81.

The embedding portion 82 is a portion for embedding solder in the fiber hole of the ferrule 713, as shown in FIGS.
(A), as shown in FIG. 14, provided on a moving stage 85, and has a pedestal 821, a mounting member 822, a syringe 823, two slide guides 824, two holding members 825, a driving member 826, and a tray 827. ing. The mounting member 822 is shown in FIG.
As shown in (a), each slide guide 824 having a stopper (not shown) slidably supports the base 821 in a vertical direction, and is urged upward by a spring 824a attached to a linear shaft of each slide guide 824. ing.

As shown in FIG. 14, the syringe 823 has a body 823a for accommodating a solder paste and a piston 823b, and is held by each holding member 825 with a discharge port 823c facing upward. The holding member 825 is attached to the side plate 828 fixed to the attachment member 822, has a V-groove plate having a V-groove and a holding arm, and positions the body 823a with the V-groove plate to hold the syringe 823. ing.

As shown in FIG. 14, the driving member 826 is supported by the supporting member 822, and presses the piston 823b of the syringe 823 to discharge the solder paste from the discharge port 823c.
The driving member 826 is a member configured in the same manner as the first elevating stage 712, and includes a support plate 826a, a main body 826b, a screw shaft 826c, a slider 826d that moves in a vertical direction, and a pressing plate 826e.

The receiving tray 827 is provided with a discharge port 823c of the syringe 823.
This is a dish for storing the solder paste discharged from the container. Here, every time the solder paste discharged from the discharge port 823c of the syringe 823 supplies the solder to the main body 71 of the head unit 7, a scraper member 829 (see FIG. a), see FIG. 15).

The scraping portion 83 is a portion for scraping off excess solder protruding from the end face of the ferrule 713 after embedding the solder or adhering to the end face and wiping it off.
As shown in FIG. 8, the support plate 831, two slide guides 83
2. It has a scraping roll 833 and a winding pulley 834.
The support plate 831 is vertically slidably supported by two slide guides 832 provided on the base 83a. The support plate 831 is urged upward by a predetermined spring force by a coil spring 835 mounted on the upper part of two side plates 83b provided on both sides of the base 83a. Support plate 831
The timing pulley 831a is rotatably supported on the front surface at the lower center, and the timing pulley 831a is
A drive motor 831b for rotating 1a is provided. The support plate 831 has an arm 836 attached to a lower part on the front surface.

As shown in FIG. 17, the arm 836 is rotatably attached to the support plate 831 at substantially the center, and a pinch roller 836a provided at the end on the timing pulley 831a side.
And a pin 836b for hooking a spring (not shown) for urging the arm 836 so that the pinch roller 836a contacts the timing pulley 831a. In addition, a detection piece 831c for detecting the ascending position of the support plate 831 is mounted on one side of the support plate 831 in cooperation with the photo sensor 837 mounted on the side plate 83b. Here, the upward movement position of the support plate 831 is regulated by a stopper cylinder 838 provided on the side plate 83b. The stopper cylinder 838 is
The shaft 8 whose tip abuts the regulating part 831d provided on the side of
38a.

The slide guide 832 has a linear shaft 832a and a linear bush 832b attached to the support plate 831 as shown in FIG. Roll 833
As shown in FIG. 16, is a roll around which a scraping material 833a such as a non-woven fabric is wound, and is rotatably arranged at the upper left of the support plate 831. The scraping material 833a is sandwiched between the timing pulley 831a and the pinch roller 836a, and is wound at a constant speed.
It is wound up.

The take-up pulley 834 is disposed at the upper right portion of the support plate 831 and is rotated by a take-up motor 834a disposed on the back side to take up the surplus length of the cut-off material 833a. Here, in FIG. 16, reference numeral 839 is an air slide table. The monitor unit 84 is a part for checking the state of the solder attached to the optical fiber 714 of the head unit 7, and is shown in FIG.
As shown in FIGS. 0, 11, and 12 (b), a CCD camera 843 provided on a mounting bracket 841 provided on a base 80, and provided on a support bracket 842, and a lens barrel mounted on the camera 843.
Has 844. Here, the lens barrel 8 is mounted on the moving stage 85.
A mirror 845 (FIGS. 11 and 12B)
See). The mounting base 841 has a support 8
46 is provided, and a scraper member 829 is installed on the upper part. The scraper member 829 is a compact slide 8
29a and a scraper 829b provided on the tip end side of an arm that expands and contracts by a compact slide 829a.

The moving stage 85 is a stage on which the cleaning section 81, the embedding section 82, and the cutting section 83 are placed and moved in the X-axis direction. Here, in FIGS.
a is a cable protection member for supplying power to the driving means of the moving stage 85. The bump forming apparatus 1 according to the present embodiment configured as described above forms minute solder bumps on the substrate S based on a solder bump forming method described below.

First, in the bump forming apparatus 1, when the power is turned on, a command signal for starting preheating of the substrate is output from the controller 9 to the preheating unit 6. Thereby, the preheating plate 6a
Preheating is started by the built-in heater. Here, the heater temperature is controlled by the controller 9 based on the measured value of the temperature sensor installed in the heater so as to maintain the set temperature.

Next, the substrate S is carried in from the carry-in entrance of the housing 2, and is carried to the preheating unit 6 by the conveyor 5. Then, the transported substrate S is positioned by the positioning pins provided on the conveyor 5, and then the preheated plate 6a
Rises into contact with the lower surface, and preheating is performed for 10 to 60 seconds. Next, the head unit 7 moves the X-axis robot 3
Is moved to the supply unit 8 by the two Y-axis robots 4. At this time, the X-axis robot 3 and the Y-axis robot 4
Is controlled by the controller 9 such that the detection piece 723b is detected by the photo sensor 721a in the head unit 7 and the elevating plate 711, and thus the ferrule 713, is in the ascending position and does not operate unless it is confirmed that there is no obstacle to the movement. ing.

The head unit 7 is moved to the supply unit 8 and the ferrule 713 held by the lifting plate 711 is moved to the cleaning unit 8.
1, the solder amount data necessary to form the solder bumps is sent from the controller 9 to the supply unit 8.
Is forwarded to As a result, the head unit 7 and the supply unit 8 start operating in a preset order while being controlled by the controller 9.

That is, the ferrule 7 held on the lifting plate 711
When 13 stops immediately above the opening 81a of the cleaning unit 81, the cleaning unit 81 and the moving unit 72 of the head unit 7 start operating. In the head unit 7, the moving unit 72
The second elevating stage 722 is operated to move the elevating plate 7
11 is lowered, and the tip of the ferrule 713 is inserted into the opening 81a of the cleaning unit 81. At this time, the tip of the optical fiber 714 slightly protrudes from the tip of the ferrule 713.

Then, in the cleaning section 81, alcohol is injected from the injection nozzle 812 toward the tip of the ferrule 713, and the fiber hole and the optical fiber (both not shown) are cleaned. When the cleaning is completed, the second elevating stage 722
Raises the elevating plate 711 slightly, and pulls out the ferrule 713 from the opening 71a. Next, pressurized air is ejected from the air nozzle 811 of the cleaning unit 81 toward the tip of the ferrule 713, and alcohol remaining around is blown off, and the cleaning of the ferrule 713 is completed. When the cleaning is completed, the second elevating stage 722 raises the elevating plate 711 to the original height.

Next, embedding of solder in a fiber hole (not shown) of the ferrule 713 is executed as follows. First, the moving stage 85 is moved in the X-axis direction, and the embedding part 82 is moved to just below the ferrule 713 held by the elevating plate 711 and stopped. Next, the driving member 82 of the embedded portion 82
6, the piston 823b is pressed by the pressing plate 826e, and the solder paste is slightly pushed out from the discharge port 823c. Thereafter, the first lifting stage 712 of the head unit 7 operates to raise the optical fiber 714 to form a space of a predetermined size in the fiber hole of the ferrule 713.

Next, the second elevating stage 722 of the head unit 7 is operated to lower the elevating plate 711, and the end face of the ferrule 713 held is pressed onto the extruded solder paste, so that the ferrule 713 is inserted into the fiber hole. Embed solder paste. When the embedding of the solder paste is completed, the second elevating stage 722 raises the elevating plate 711 to its original height and stops. At this time, the ferrule 713 has extra solder paste attached to the end face in addition to the fiber hole.

Thereafter, the cut-off portion 83 starts operating, and the excess solder paste adhered to the end surface of the ferrule 713 is wiped off as follows in the following manner. First, the moving stage 85 is moved in the X-axis direction until the cutting roller 833 of the cutting section 83 is located immediately below the ferrule 713. Next, the second elevating stage 722 is operated to lower the elevating plate 711, and press the held end surface of the ferrule 713 against the cutoff material 833a. In this state, the moving stage 85
Is further moved slightly in the X-axis direction, and excess solder paste attached to the end surface of the ferrule 713 is wiped off with a scraping material 833a. When the scraping is completed, the second lifting stage 722 raises the lifting plate 711 to the original height and stops.

Next, in the head unit 7, the first elevating stage 712 is operated, and the slider 712d is slightly lowered slightly more than the amount corresponding to the amount of the solder paste embedded in the fiber hole of the ferrule 713. As a result, the optical fiber 714 fixed to the fixing plate 716 by the holding plate 717 descends and is pushed out from the end face of the ferrule 713 by about 0.02 mm. Along with this, the solder paste embedded in the fiber hole by the optical fiber
It is extruded while attached to 714. The extruded solder paste is photographed by the CCD camera 843 of the monitor unit 84, and the presence or absence of the solder paste, the amount of solder attached, and the like are checked. If the adhesion state is good, the process proceeds to the next step. If the adhesion state is bad, the process returns to the step of cleaning the tip of the ferrule 713, and the steps of embedding and scraping are repeated.

When the solder paste attached to the optical fiber 714 is in a good condition, the solder paste is
The head unit 7 is moved to the substrate S by the X-axis robot 3 and the Y-axis robot 4 while being pushed out to the end face of the 713. Then, the elevating plate 711 is moved down by the second elevating stage 722, and a predetermined amount of solder paste adhered to the optical fiber 714 is adhered on a copper pad (not shown) of the substrate S. The solder light is melted by the heating light sent through to form minute solder bumps.

At this time, when the elevating plate 711 descends, first, the solder paste attached to the tip of the optical fiber comes into contact with the copper pad. Further, when the elevating plate 711 is further lowered, the solder paste is appropriately crushed so as not to be divided and securely adheres to the copper pad, and a drag force equivalent to a contact pressure acts on the optical fiber 714 via the crushed solder paste. . Then
Since the lifting plate 711 is supported by the moving portion 72 with a spring force of about several grams by the constant tension spring 724 and the tension spring 727, the lifting plate 711 is slightly lifted by the slider 715 being guided by the guide member 723 due to the reaction force. I do.

The vertical position of the guide member 723 and the vertical plate 711 changes as the vertical plate 711 rises. The vertical distance is calculated from the distance signal output from the sensor 73 to the controller 9. Is done. Then, the controller 9 raises the head unit 7 by the second lifting stage 722 by an amount obtained by adding an arbitrary offset distance to the calculated relative distance, and removes the optical fiber 714 and the solder paste adhered on the copper pad of the substrate S. A gap is formed between them.

Here, the offset distance is such that when the solder paste adhered to the substrate S from the optical fiber 714 is heated and melted to form a solder bump, the molten solder interferes with the tip of the optical fiber 714; The distance is set so that the shape of the formed solder bump is not distorted and the solder is sufficiently melted by the heating light from the LD module 725 emitted from the optical fiber.

With the gap formed in this manner, the solder is sufficiently melted by the heating light from the LD module 725 to form fine solder bumps on the copper pads of the substrate S. As described above, since the substrate S is preliminarily heated by the preheating unit 6, the solder can be quickly melted even with weak light. As described above, the bump forming apparatus 1 of the present embodiment
When forming a solder bump on the substrate S, forming a fine solder bump of an appropriate shape at a desired position on the substrate S while detecting the relative distance between the elevating plate 711 and the moving unit 72 with the sensor 73. Can be.

The substrate S on which the formation of the solder bumps has been completed as described above is conveyed to the carry-out port by the conveyor 5 and discharged, and a new substrate S is carried in from the carry-in port. The bump forming operation is repeated. Here, as described above, the head unit 7 adjusts the amount of insertion of the optical fiber 714 into the fiber hole of the ferrule 713 as appropriate, so that the solder embedded in the space formed by the fiber hole and the optical fiber 714 is formed. Can be set to a desired amount. Therefore, when the amount of solder of the solder bumps formed on the substrate S is small, it is possible to add a desired amount of solder to the solder bumps.

In the above embodiment, the ferrule
Although the 713 is used as a die and the optical fiber 714 is used as a punch, an appropriate amount of solder may be adhered to the substrate S using a die and a punch corresponding to the size of a desired solder bump. Further, as the heating source, the solder may be heated by heating the dice (ferrule) by heat conduction, or non-contact heating may be performed by a laser or the like.

Further, in each of the above embodiments, the case where a single-core optical fiber is inserted into the through-hole of the dice has been described. However, if the solder bumps having an appropriate shape can be formed stably, the number of dice is large. It goes without saying that a multi-core ferrule for a core connector may be used.

[0062]

According to the first aspect of the present invention, an appropriate amount of solder bumps can be formed at a time without heating in a reflow furnace, and the arrangement pitch of the solder bumps can be reduced. There is an excellent effect. According to the second aspect of the present invention, since the heating region can be localized at a required portion, there is an excellent effect that a solder bump can be formed in a narrow region without adversely affecting the surroundings. .

According to the third aspect of the present invention, since the punch is cleaned before the solder paste is embedded, the solder paste can be appropriately embedded in the depression formed in the punch, and the amount of the solder paste can be accurately determined. You can control well. According to the invention as set forth in claim 4, since the excessive solder paste is wiped off from the end face of the ferrule, the excess solder paste adhered to the ferrule end face when transferring the copper pad or the defective solder pad solder paste. Can be suppressed.
Also, the amount of the solder paste becomes more accurate.

Further, according to the invention described in claim 5, the inventions described in claims 1 to 4 can be realized.

[Brief description of the drawings]

FIGS. 1A to 1E are explanatory views of one embodiment of a solder bump forming method according to the present invention.

FIGS. 2A to 2D are explanatory views of another embodiment of the solder bump forming method according to the present invention.

FIG. 3 is a front view of the solder bump forming apparatus of the present invention (FIG. 3);
(A)) and a side view (FIG. 3 (b)).

FIG. 4 is a plan view of the solder bump forming apparatus of the present invention (FIG. 4).
(A)) and a rear view (FIG. 4 (b)).

FIG. 5 is a front view of a head unit used in the solder bump forming apparatus of the present invention.

FIG. 6 is a right side view of the head unit of FIG. 5;

FIG. 7 is a right side view showing a partial cross section of the head unit of FIG. 6;

FIG. 8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a left side view of the head unit of FIG. 5;

FIG. 10 is a front view showing a solder supply unit provided in the solder bump forming apparatus.

FIG. 11 is a plan view of the supply unit of FIG. 10;

12 is a side view (FIG. 12 (a)) showing a buried portion of solder and a monitor unit for monitoring the adhesion state of the solder provided in the supply unit of FIG. (FIG. 12B).

FIG. 13 is an enlarged view of a main part of a cleaning unit provided in the supply unit of FIG. 10;

14 is a rear view of a solder embedding portion provided in the supply unit of FIG. 10;

FIG. 15 is an enlarged view in which the tip end side of a syringe provided in a solder embedding portion provided in the supply unit of FIG. 10 is enlarged.

FIG. 16 is a front view showing a cutoff portion of the solder provided in the supply unit of FIG. 10;

FIG. 17 is a plan view showing a cross section of the frayed portion in FIG. 16;

FIG. 18 is a side view showing a cross section of the frayed portion in FIG. 16;

FIGS. 19A to 19C are explanatory views of a conventional solder bump forming method.

FIGS. 20A and 20B are explanatory views of another conventional solder bump forming method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solder bump forming apparatus 2 Housing 3 X-axis robot 4 Y-axis robot 5 Conveyor 6 Preheating part 7 Head unit 71 Main part 711 Holding member 712 First elevating stage 713 Ferrule 714 Optical fiber 72 Moving part 722 Second elevating stage 723 Guide member 724 Constant tension spring 725 Laser diode module 73 Sensor 8 Supply unit 80 Base 81 Cleaning unit 82 Embedding unit 83 Scratching unit 84 Monitor unit 85 Moving stage 20 Holder 21 Punch 21a End surface 22 Die 22a End surface 22b Depression 22c Through hole 23, 23a Solder Paste 23b Solder ball 24 Substrate 25 Copper pad 26 Light heating source 27 Solder bump 28 Optical fiber 28a End face

Claims (5)

[Claims] 1. A step of drawing an end face of a punch inserted into a through-hole provided in a die by a desired distance from an end face of the die to form a recess having a desired volume in the end face of the die, wherein a solder paste is provided in the recess. A step of embedding the solder paste, a step of moving the punch toward the die end face to extrude the solder paste, and a step of melting the solder paste extruded by the movement of the punch. 2. The method according to claim 1, wherein the punch comprises an optical fiber, and the solder paste is melted by heating light passing through the optical fiber. 3. The method according to claim 1, further comprising a step of cleaning the punch before the step of embedding the solder paste. 4. The method according to claim 1, further comprising the step of scraping off the solder paste on an end face of the die in which the solder paste is embedded. 5. A die provided with a through-hole, a punch slidably inserted into the through-hole, means for embedding solder paste in a depression formed by the through-hole and the punch, and Means for extruding the solder paste to the die end face by sliding in a through hole of the die,
A heating source for melting the solder paste.