JP2743058B2 - Method and apparatus for removing microspheres - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is preferably applied to a method in which, when a bump made of a fine metal sphere is joined to an inner lead, an electrode of a film carrier, an electrode of a semiconductor chip or the like, the fine metal sphere is arranged and fixed. For removing extra fine metal spheres from an array substrate for use in the method.

[0002]

2. Description of the Related Art As bumps that serve as a bonding medium between a so-called inner lead of a film carrier and an electrode of a semiconductor chip,
Wafer bumps, stud bumps, transfer bumps and the like are known. After the semiconductor is manufactured, a barrier metal is formed on the electrode pads in the form of a wafer, and A is formed thereon.
The bumps such as u are formed by plating. However, this wafer bump not only causes an increase in the number of process steps and causes a decrease in the yield of semiconductor devices, but also has a problem that it is not worth the cost especially for a small number of high-mix products.

The stud bumps are formed one by one by performing ball bonding at the time of primary bonding of wire bonding to electrode pads of the semiconductor chip one by one, and cutting the neck portion of the wire after bonding. The remainder of the wire in the portion remains convex and non-uniform. For this reason, when such bumps are used, the bonding reliability becomes considerably low. In addition, it takes time to bump one pin at a time.

Further, as a method of joining a bump to an inner lead of a film carrier, in a transfer bump in which a bump grown by plating on a substrate is joined to the inner lead, the bump formed by plating is a hemispherical bump. For this reason, the bump width becomes larger than the bump height required for bonding, which is not particularly suitable for narrow pitch bonding of 100 μm or less.

In order to cope with such a problem, a method of forming a bump in which minute metal spheres are arranged in advance at the same coordinates as the electrode pads of the semiconductor and are joined together on the electrodes has been studied. I have.

[0006]

However, in the conventional bump bonding or forming method, when arranging minute metal spheres on an arrayed substrate, extra metal spheres adhere to the substrate due to static electricity or the like, There was a problem that the balls would adhere to each other. Such extra fine metal spheres must be surely removed from the substrate, but it is difficult to accurately remove only extraneous metal spheres because they are small and use a large number of metal spheres.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method and an apparatus for removing microspheres capable of reliably and quickly removing extra fine metal spheres when arranging them on an array substrate.

[0008]

The method for removing microspheres according to the present invention is preferably applied to, for example, bumps made of fine metal spheres. However, a large number of microspheres are arranged at predetermined positions on an array substrate. By applying ultrasonic vibration to the array substrate,
An extra microsphere attached to the array substrate is removed. In this method for removing microspheres, particularly, the microspheres are fixed to the array substrate by vacuum suction.

The apparatus for removing microspheres according to the present invention comprises an ultrasonic vibration source for applying ultrasonic vibration to an array substrate having a large number of array holes for arraying and fixing microspheres. A source is operated to ultrasonically vibrate the array substrate. In this microsphere removing apparatus, an ultrasonic vibrator as an ultrasonic vibration source is built in the array substrate or provided outside the array substrate.

[0010]

According to the present invention, an ultrasonic vibrator is provided as an ultrasonic vibration source capable of applying ultrasonic vibration to an array substrate for arranging and fixing microspheres. By operating the ultrasonic vibrator, ultrasonic vibration is applied to the array substrate to which the extra fine metal spheres are attached, or to the member fixing the array substrate. As a result, extra microspheres attached to the array substrate are instantaneously removed. Therefore, a large number of microspheres can be properly and reliably arranged at predetermined positions on the arrangement substrate.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method and an apparatus for removing microspheres according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a typical configuration example of a microsphere removing apparatus 1 according to the present invention. In this embodiment, an ultrasonic vibrator 2 as an ultrasonic vibration source is provided. This ultrasonic vibrator 2 is connected via a wiring 3 to a control device 4 for controlling the ultrasonic vibration. In the present embodiment, the microsphere to which the present invention is applied is preferably, for example, a micrometal sphere B constituting a bump.

In FIG. 1, the array substrate 10 has an adsorption hole 11 for adsorbing and fixing the minute metal spheres B, and a base material 12 is connected via a suction pipe 14 to a vacuum source such as a vacuum pump. (Not shown). The array substrate 10 is accurately positioned and fixed to the base material 12 such that the suction holes 11 and the suction holes 13 are aligned. Specifically, the hole diameter of the suction holes 11 is 30 μm, and for example, 328 holes are provided in a predetermined pitch and arrangement pattern. In the present embodiment, the array substrate 10 and the base material 12 are formed separately, but they may be integrally formed to form a single array substrate (integral array substrate) as a whole. Good. The ultrasonic vibrator 2 is incorporated in a form embedded in the base material 12, that is, is incorporated therein. The frequency and amplitude of the ultrasonic vibration to be generated by the ultrasonic vibrator 2 are appropriately controlled by the control device 4.

Next, a method for removing microspheres using the apparatus of the present invention having the above-described configuration will be described. When the vacuum source is evacuated through the suction tube 14, the minute metal spheres B are drawn into the suction holes 1.
Adsorbed to 1. In this embodiment, Au having a spherical diameter of 40 μm is used.
Although a (F) fine metal sphere B is used, it is basically preferable that one fine metal sphere B is adsorbed to one adsorption hole 11. By the way, as shown in FIG. 1, due to static electricity or the like, the surface of the
In some cases, extra fine metal spheres B ′ may adhere to the fine metal spheres B that are properly adsorbed to the first. Although this extra fine metal sphere B 'depends on the total number of the fine metal spheres B to be properly adsorbed to the suction hole 11, about 5 to 10 extra fine metal spheres B' are used in this embodiment. Adhere to.

When the ultrasonic vibrator 2 is operated by the control device 4, ultrasonic vibration is applied to the substrate 12 and the array substrate 10. The frequency of the ultrasonic vibration is preferably 50 kHz. By oscillating the array substrate 10 in this manner, any extra fine metal spheres B 'attached to the array substrate 10 are instantaneously removed.
0, and falls into a collection dish (not shown) installed below the array substrate 10. After confirming that the minute metal spheres B 'have been completely removed from the array substrate 10, the operation of the ultrasonic transducer 2 is stopped. In the above case,
The operation timing of the ultrasonic vibrator 2 may be synchronized with the suction of the minute metal spheres B, that is, always activated when the minute metal spheres B are attracted to the array substrate 10. In this case, it is possible to prevent the extra fine metal spheres B 'from being attached at the same time as the fine metal spheres B are adsorbed to the suction holes 11.

Here, the ultrasonic transducer 2 may be fixed to the back surface of the substrate 12 as shown in FIG. In this case, the ultrasonic vibrator 2 is fixed in place on the base material 12 using screws or the like. Thus, the ultrasonic vibrator 2 is
Even in the case of externally attaching to the two or one integrated array substrate, ultrasonic vibration is applied to the array substrate 10 in the same manner as described above, and the extra small metal sphere B 'can be completely removed. In particular, in this case, the size of the base 12 does not need to be increased.

Further, as shown in FIG. 3, the ultrasonic vibrator 2 can be fixed to the base material 12 using, for example, an appropriate adhesive 5. Then, the ultrasonic transducer 2 is brought into close contact with the base material 12 with the adhesive 5. Note that, instead of the adhesive 5, a rubber material or high-viscosity grease may be interposed between the base material 12 and the ultrasonic vibrator 2 to fix the ultrasonic vibrator 2.

In the above description, the ultrasonic vibrator 2
An example in which the ultrasonic vibration source is built into the array substrate 10 and the base material 12 (or an integrated array substrate) (FIG. 1) or externally attached (FIGS. 2 and 3) is shown. 12 may be provided separately and separated from each other, and ultrasonic vibration may be applied to the array substrate 10 via a certain medium (for example, water). In this case, the ultrasonic vibration generated by the ultrasonic vibration source propagates through the medium, thereby applying the ultrasonic vibration to the array substrate 10.

Further, as a method of applying ultrasonic vibration to the array substrate 10, it is possible to apply ultrasonic vibration by mechanically bringing an ultrasonic vibration source into contact with the array substrate 10. That is, as shown in FIG. 4, for example, the array substrate 10 on which the minute metal spheres B are adsorbed is mounted and fixed on a predetermined stage 6, and the ultrasonic vibration source The capillary 7 of, for example, a wire bonder as 1 'is brought into contact with a certain load (approximately 100 gf) while the capillary 7 is ultrasonically vibrated.

By applying the ultrasonic vibration through the capillary 7 as described above, the extra fine metal spheres B 'can be completely removed from the array substrate 10; A predetermined amount of air blow is applied to the surface to forcibly remove extra small metal spheres B ′ floating from the array substrate 10. When the arrangement substrate 10 is fixed upside down from the case of FIG. 4, it is not necessary to apply air blow, and in this case, an extra fine metal ball B 'falls naturally.

Next, specific application examples of the present invention will be described.
In particular, a description will be given of an example of a step of bonding the minute metal sphere B to the inner lead of the film carrier or the electrode chip of the semiconductor chip.

First, as shown in FIG. 5, the bonding apparatus used in this bonding step includes, as main components, a microsphere array mechanism 100, a substrate transport mechanism 200, and a microsphere recognition means 3.
00 and a joining stage 400. In addition,
This device can be configured by adding a function of arranging and joining minute metal spheres to a device having a joining mechanism such as an inner lead bonder.

Next, in the microsphere arrangement mechanism 100,
As shown in FIG. 6, the microsphere stock dish 101 is vibrated. That is, a metal microsphere stock dish 101
A small metal sphere B is put in the box and vibrated by a vibration generator 102 such as a parts feeder. Thereby, the minute metal sphere B floats effectively. The vibration frequency at this time is a minute metal ball B
Variable from 0 to 1 kHz depending on the size of
The microsphere stock dish 101 is detachable from the vibration generator 102.

Next, the fine metal spheres B are adsorbed on the array substrate 10 and the base material 12 according to the present invention. The substrate 12 has the array substrate 10 in which the suction holes 11 smaller than the spherical diameter are arranged at predetermined positions as described above, and it is preferable that the suction holes 11 are provided for a plurality of semiconductor chips. Then, the base material 12 is turned upside down, lowered to the vicinity of the microsphere stock dish 101, and the fine metal spheres B are vacuum-sucked into the suction holes 11 of the arrayed substrate 10 while swinging up and down. Here, substrate 1
2, the descending distance and the amplitude distance can be controlled in units of 0.1 mm, and the number of amplitudes can be controlled. At this time,
When the base material 12 is slightly vibrated in the horizontal direction, the number of the minute metal spheres B that are excessively adsorbed is suppressed to a minimum, and the adsorbing can be performed more effectively.

Now, the base material 12 is raised and the control device 4
When the ultrasonic vibrator 2 is operated, ultrasonic vibration is applied to the array substrate 10. As a result, all the extra fine metal spheres B 'instantly separate from the array substrate 10 and fall as shown in the figure. In addition, the ultrasonic vibrator 2
May be set so that the array substrate 10 is ultrasonically vibrated simultaneously with the adsorption of the minute metal spheres B.

Next, as shown in FIG. 7, the base material 12 from which excess microspheres have been removed is moved to a recognition position, and the presence or absence of microspheres and the presence or absence of microspheres are image-recognized by the microsphere recognition means 300. If a defect occurs during microsphere recognition,
By the vacuum leak and the mechanical removal, all the adsorbed fine metal spheres B are collected, and the fine sphere adsorption is performed again.

Next, the substrate 12 is transported to the bonding stage 400 by the substrate transport mechanism 200 shown in FIG. At the time of this transfer, the minute metal sphere B is prevented from dropping due to vibration or the like.

Next, as shown in FIG. 7, the conveyed substrate 12 is turned over, and mounted and fixed on a bonding stage 400. The bonding stage 400 is shared with the main stage of the bonding apparatus, and the stage is fixed by vacuum suction. Joining stage 4
Alignment is performed between the fine metal spheres B of the array substrate 10 of the base material 12 set to 00 and the inner leads 20 of the film carrier. For this, the alignment mechanism of the main unit can be used. Then, after the alignment, the minute metal balls B are bonded (transferred) to the inner leads 20. This joining can be performed using the function of the inner lead bonder device main body.

When bonding the fine metal balls B to the electrode pads of the semiconductor chip, the semiconductor chip 30 is placed on the bonding stage 400 as shown in FIG. Then, the minute metal sphere B is lowered without being inverted, and the minute metal sphere B is brought into contact with the electrode pad of the semiconductor chip 30, and the substrate 12 is pressed by the heating tool 500 to join the minute metal sphere B to the electrode pad. .

Further, an example in which the present invention is applied to a printed circuit board (PCB) and the solder is supplied quantitatively will be described. By the way, QFP, TSOP, TCP, etc.
When surface mounting on the CB, solder is plated or printed on the pads of the PCB to be joined. For example, when a multi-pin package is mounted in a small area, the package may have an outer lead pitch of 0.3 mm or less. However, it is practically impossible to implement by the conventional leveler method, for example, and other methods still have many problems in cost and quality.

The printed circuit board 40 has a large number of pads 42 arranged at a predetermined pitch (0.15 mm) and in a pattern on a board 41 as shown in FIG. 9, for example. The array substrate 10 'has a number of suction holes 11' corresponding to the pads 42 as shown in FIG. The suction holes 11 'are formed in consideration of the pitch and length (2.0 mm) of the pads 42. In this example, the suction holes 11' have a hole diameter of 50 m. The array substrate 10 'is also made of stainless steel or glass material with a thickness of 0.2 mm.

In this application example, the microspheres have a sphere diameter of 70 μm.
As shown in FIG. 11, the microsphere stock dish 101 containing the microspheres B is set in the vibration generator 102 as shown in FIG. And this microsphere stock dish 1
By oscillating 01 at a frequency of about 400 Hz, the minute metal sphere B floats effectively. Next, the base 12 'is lowered with the arrangement substrate 10' facing downward, and the floating fine metal spheres B are adsorbed to the suction holes 11 'of the arrangement substrate 10'. Thereafter, the base material 12 'is raised, and the ultrasonic vibrator 2 is operated by the control device 4, so that the array substrate 10'
By supersonic vibration, all the extra fine metal spheres B 'are instantaneously removed from the array substrate 10',
By this step, the minute metal spheres B can be reliably and accurately arranged on the arrangement substrate 10 '.

Next, as shown in FIG. 12, the presence / absence of microspheres missing or surplus microspheres is image-recognized by the microsphere recognition means 300, and the printed circuit board 40 fixed at a predetermined position on the bonding stage 400 is connected to the printed circuit board 40. Is performed (alignment). The pad 42 of the printed circuit board 40
A flux 43 is applied on the upper surface in advance to improve the solder leakage to the pad 42 in a later reflow process. Next, after the alignment is completed, the base material 12 ′ is lowered to the printed circuit board 40, and the minute metal spheres B are bonded or adhered to the pads 42. Then, by heat-treating the printed circuit board 40, the solder leaks to the pads 42, and finally the printed circuit board 40 having a uniform amount of solder is obtained. Thus, even in the case of the printed circuit board 40, quantitative solder supply can be realized.

Further, as an application example of the above-mentioned method for removing microspheres, the method can be effectively applied to solder supply after repair. For example, as shown in FIG.
When a plurality of semiconductor packages 50, 51, and 52 are mounted on the semiconductor chip 0 (FIG. 13A), for example, the semiconductor package 51 is removed, and solder remaining on the printed circuit board 40 after the repair is removed. Removed. Then, as shown in FIG. 13B, the above-described quantitative solder supply is performed between the semiconductor packages 50 and 52 on the printed circuit board 40. That is, as shown in the figure, the base material 12 'having the arrayed substrate 10' on which the minute metal spheres B are adsorbed is aligned, and in this case also, the solder can be supplied quantitatively.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various effective modifications and applications are possible based on the technical idea of the present invention. For example, although the example of the minute metal sphere B which is a bump or a solder sphere has been described as the microsphere in particular, the above-described embodiment is also applicable to the case where this kind of bonding is performed using the microsphere made of a conductive rubber material. As in the case described above, by oscillating the array substrate with ultrasonic waves, the extra microspheres attached to the array substrate can be completely removed.

[0036]

As described above, according to the present invention,
In this type of bonding of microspheres, by applying ultrasonic vibration to the array substrate, extra microspheres can be completely removed from the array substrate. Particularly, in the case of a large number of extremely minute metal spheres, there is a case where they are easily adhered to the array substrates or to each other with only a slight electrostatic force. Ultrasonic vibration is extremely effective for such a small metal sphere. By applying this vibration energy, for example, when using a small metal sphere as a bump, the inner lead of a film carrier, an electrode or an electrode on a semiconductor chip is used. This has the advantage that bumps to be bonded to pads and the like can be arranged reliably and accurately, and quality and productivity can be effectively and greatly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a typical configuration example of a microsphere removing device of the present invention.

FIG. 2 is a sectional view showing a modified example of the microsphere removing device of the present invention.

FIG. 3 is a sectional view showing another modified example of the microsphere removing device of the present invention.

FIG. 4 is a sectional view showing another modified example of the microsphere removing device of the present invention.

FIG. 5 is a schematic plan view showing the configuration of the entire apparatus for bonding micro metal spheres in a specific application example of the present invention.

FIG. 6 is a schematic diagram showing a microsphere arranging operation by a microsphere arranging mechanism in the bonding apparatus according to the present invention.

FIG. 7 is a schematic view showing a microsphere bonding to a lead of a film carrier in the bonding apparatus according to the present invention.

FIG. 8 is a schematic view showing microsphere bonding to a semiconductor chip to an electrode pad in the bonding apparatus according to the present invention.

FIG. 9 is a schematic plan view of a printed circuit board according to a specific application example of the present invention.

FIG. 10 is a schematic plan view of an array substrate for the printed circuit board according to the microsphere removing device of the present invention.

FIG. 11 is a schematic diagram showing a microsphere arranging operation by a microsphere arranging mechanism in an application example of the present invention to the printed circuit board.

FIG. 12 is a schematic diagram showing a supply of solder to a pad in an example in which the present invention is applied to the printed circuit board.

FIG. 13 is a schematic view showing an application example of the present invention applied to the printed circuit board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microsphere removal apparatus 2 Ultrasonic transducer 3 Wiring 4 Controller 5 Adhesive 6 Stage 7 Capillary 10 Array substrate 11 Suction hole 12 Base material 13 Suction hole 14 Suction tube 20 Inner lead 30 Semiconductor chip 40 Printed circuit board 41 Substrate 42 Pad 50, 51, 52 semiconductor package 100 microsphere arrangement mechanism 200 substrate transport mechanism 300 microsphere recognition means 400 bonding stage

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-48-15057 (JP, A) JP-A-51-7043 (JP, A) JP-A-52-130810 (JP, A)

Claims (9)

(57) [Claims] 1. A method in which a large number of microspheres are arrayed and held in vacuum holes at predetermined positions on an array substrate by vacuum suction, and ultrasonic vibration is applied to the array substrate, thereby excluding the microspheres other than the arrayed microspheres. A method for removing microspheres, comprising removing extra microspheres. 2. The method according to claim 1, wherein the microspheres are made of a metal or a conductive rubber material. 3. An array substrate having a large number of array holes for arraying and supporting microspheres in vacuum holes at predetermined positions by vacuum suction, and extra microspheres other than the microspheres arrayed and supported on the array substrate. And an ultrasonic vibration source for applying ultrasonic vibration to the array substrate so as to remove the microspheres. 4. The apparatus according to claim 3, wherein the microspheres are made of a metal or a conductive rubber material. 5. The apparatus for removing microspheres according to claim 3, wherein an ultrasonic vibrator is built in the array substrate. 6. The apparatus for removing microspheres according to claim 3, wherein an ultrasonic transducer is provided outside the array substrate. 7. The apparatus for removing microspheres according to claim 3, wherein the ultrasonic vibration source applies ultrasonic vibration to the array substrate via a fixed medium. 8. The apparatus for removing microspheres according to claim 3, wherein the ultrasonic vibration source is brought into contact with the array substrate to apply ultrasonic vibration to the array substrate. 9. The microscopic device according to claim 7, wherein the ultrasonic vibration is transmitted to the array substrate via an adhesive fixing material from an ultrasonic transducer bonded and fixed to the outside of the array substrate. Ball removal device.