JPH11251370A - Method and device for supplying conductive adhesive and chip mounter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten process time and to considerably reduce the amount of used conductive adhesive, by forming conductive adhesive on the surface of a plate, and forming the conductive adhesive of prescribed thickness on bumps formed on a device. SOLUTION: The layer 103 of conductive adhesive is formed on a plate 101 whose surface is plane in a pattern form corresponding to bumps by using the trace supply device 102 of conductive adhesive. A semiconductor chip 201 with bumps 202 is pushed into the layer 103 of conductive adhesive. Then, the semiconductor chip 201 is pulled up and the bumps 202 are detached from the layer of conductive adhesive. The bumps 202 to which prescribed amount of conductive adhesive 107 is adhered are formed and they are used for loading the semiconductor chip 201 on a circuit board. Then, conductive adhesive left on the plate 101 is scratched away. Then, conductive adhesive using solvent whose boiling point is low can be used and therefore process time can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for supplying a conductive adhesive to bumps formed on a device for electrically connecting a semiconductor device or the like, and a chip mounter.

[0002]

2. Description of the Related Art In recent years, attention has been paid to a flip chip mounting method as a semiconductor chip mounting method. In this method, a projection (bump) of an electric conductor is formed on a pad (electrode terminal) of a bare semiconductor chip, and the bump is electrically connected to an electrode on a circuit board.

Recently, this technology has been developed because it can be mounted smaller than a package with leads like a conventional QFP (Quad Flat Package), and is suitable for high-speed operation because of shorter wiring. Remarkable. Stud bump bonding (Stud Bum)
Mounting with p bonding is highly reliable and practical use has begun.

FIGS. 2A to 2C show a flip-chip mounting process using a stud bump bonding technique. This method is described in the literature, Tomura Yoshihiro et al., "Advanced Flip Chip Bonding Technique for MC Emuel" (Yoshihiro Tomura et. Al,
"Advanced Flip Chip Bonding Technique For MCM-
L "), 1996 Proceedings of First Pan Pacific Microelectroni
cs Symposium), p125-131 (1996).
This method is based on supplying a conductive adhesive on the bump. 2A to 2C, a semiconductor chip 201 has a bump 202 formed thereon. As a first step, a plate 203 with a shallow trench 204
The squeegee 205 is used to insert the conductive adhesive 206 so that the trench 204 is full and flat (FIG. 2).
(A)). Next, in a second step, the bumps 202 on the semiconductor chip are immersed in contact with the conductive adhesive layer 206 on the plate 205 (FIG. 2B). As a third step, the semiconductor chip 201 is pulled up and a conductive adhesive 207 is attached to the surface of the bump 202 (FIG. 2C). In this manner, bumps 202 having a predetermined amount of conductive adhesive 207 attached thereto are formed, and are used to mount semiconductor chip 201 on a circuit board (not shown). Thereafter, the first step is repeated for the next semiconductor chip. There is also a method of forming a conductive adhesive layer by using a flat plate and a squeegee at a desired distance from the surface without using the plate 203 having a shallow trench 204 on the surface.

[0005]

Although the above conventional method is very simple, it has a major problem. In order to stably supply the conductive adhesive onto the bump, it is required that the properties of the conductive adhesive do not change during the operation time. However, in the above method, since the conductive adhesive is thinly spread in a plane with a squeegee, it is easy to dry, and it is difficult to keep the property of the conductive adhesive constant during operation time. The solvent used for the conductive adhesive has a high boiling point in order to keep it as constant as possible. However, in that case, as a matter of course, the drying time becomes longer when the semiconductor chip is mounted on the circuit board in the next step and the conductive adhesive is dried. For example, if a solvent having a boiling point of about 250 ° C. is used, it takes about 2 hours for drying. This time becomes a major obstacle in the process. In other words, it takes too much time and productivity is deteriorated. Also, batch processing is required, which hinders in-line processing in mass production. In addition, since the properties of the conductive adhesive are changed before the expanded conductive adhesive is used up, there is a problem that the utilization rate of the conductive adhesive is poor and most of the conductive adhesive is discarded.

According to the present invention, in order to solve the above-mentioned conventional problems, a conductive adhesive mixed with a solvent having a low boiling point can be used, so that the process time is shortened and the amount of the conductive adhesive used is extremely reduced. Provided are a method and apparatus for supplying a conductive adhesive that can be reduced, and a chip mounter.

[0007]

In order to achieve the above object, a method of supplying a conductive adhesive according to the present invention is a method for forming a conductive adhesive having a predetermined shape on a bump surface of a device. A conductive adhesive is supplied in a predetermined pattern using a micro-supply device to form a conductive adhesive layer, and a bump formed on a device is brought into contact with the conductive adhesive layer, and a predetermined It is characterized in that a conductive adhesive portion having a thickness is formed.

In the above method, the surface of the plate is:
It is preferably flat or curved. Further, in the above method, it is preferable that the device for supplying a small amount of the conductive adhesive has a storage section for sealing the conductive adhesive before application.
Further, in the above method, after supplying the conductive adhesive to the bumps formed on the device, the conductive adhesive on the plate is removed, and then a new conductive adhesive is supplied in a pattern by a micro supply device. Is preferred.

Next, an apparatus for supplying a conductive adhesive according to the present invention comprises:
A device for forming a conductive adhesive of a predetermined shape on a bump surface of a device, a micro-supply device for forming a conductive adhesive layer by supplying a conductive adhesive in a predetermined pattern on a surface of a plate, and a device Means for contacting the bump formed on the layer of conductive adhesive, means for separating the bump from the layer of conductive adhesive, and means for scraping off the remaining conductive adhesive with a knife edge. And

In the above apparatus, the surface of the plate is:
It is preferably flat or curved. Further, in the above device, it is preferable that the device for supplying a small amount of the conductive adhesive has a storage section for sealing the conductive adhesive before application.

Next, a chip mounter incorporating the conductive adhesive supply device of the present invention is a chip mounter for forming a conductive adhesive having a predetermined shape on a bump surface of a device. A micro-supply device for supplying a predetermined pattern to form a conductive adhesive layer, means for contacting the bump formed on the device with the conductive adhesive layer, and a method for transferring the bump from the conductive adhesive layer It is characterized by including means for separating and means for scraping off the remaining conductive adhesive with a knife edge.

With the above-mentioned structure, a conductive adhesive mixed with a solvent having a low boiling point can be used, and therefore the process time can be shortened and the amount of the conductive adhesive used can be extremely reduced. A method and apparatus for supplying a conductive adhesive and a chip mounter can be provided.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below more specifically with reference to the drawings. FIG. 1 (A)
As shown in the following, in the present invention, as a first step,
A conductive adhesive layer 103 is formed on a flat surface of a plate 101 using a small amount supply device 102 of a conductive adhesive 104 in a pattern corresponding to the bumps. The thickness is about half the height of the bump, and when the height of the bump is about 40 μm, the thickness of the conductive adhesive layer 103 is preferably about 15 to 25 μm. Since the micro-supply device 102 has a closed storage portion in which the conductive adhesive is stored, volatilization can be prevented even if a solvent having a boiling point of 200 ° C. or lower is used.

Next, as a second step, the semiconductor chip 201 having the bumps 202 is brought into contact with the conductive adhesive layer 103, and the bumps 202 are pushed into the conductive adhesive layer 103 (FIG. 1).
(B)). As a third step, the semiconductor chip 201 is lifted and the bump 202 is separated from the conductive adhesive layer (FIG. 1).
(C)). In this way, the bump 202 to which the conductive adhesive portion 107 is adhered by a predetermined amount is formed, and this semiconductor chip 201 is used for mounting on a circuit board (not shown). The adhesion amount of the conductive adhesive 107 parts is several μm to 5 μm from the tip of the bump.
m.

As a fourth step, the conductive adhesive 103 remaining on the plate 101 is scraped with a knife edge 106, and the scraped remaining conductive adhesive 105 is discarded (FIG. 1).
(D)). As the conductive adhesive micro-supply device 102,
A dispenser that can easily control the amount of protrusion is preferable. The thickness of the conductive adhesive layer can be controlled by adjusting the amount of protrusion, the distance between the needle tip and the plate, and the feed speed. This thickness is related to the amount of the conductive adhesive when transferring (supplying) the conductive adhesive by contacting the bumps, and must be strictly controlled for uniform supply. According to the method of the present embodiment in which the conductive adhesive is supplied onto the plate by the dispenser, the thickness of the layer can be accurately controlled. For example, the same level of management as the conventional method using a squeegee (fluctuation in layer thickness ± several μm) can be easily performed.

Further, since the conductive adhesive is held in a sealed container until it is supplied onto the plate,
The solvent does not evaporate and its properties do not change. For example, an ester or ketone solvent having a boiling point of about 160 to 200 ° C. can be used. With such a solvent, drying can be performed in about 10 minutes.
Therefore, in-line (or on-line) drying process
Becomes possible. Although a conductive adhesive can be prepared using a solvent having a lower boiling point, drying tends to be too fast and it becomes difficult to supply a small amount.

In the above example, a plate having a flat surface is used, but the plate need not always be flat. A cylindrical surface may be used. The device can be inexpensive because rotational motion is available. In this case, the envelope surface at the tip of the bump must fit the surface of the cylinder. Two rows of bumps correspond to this. Even if the envelope surface at the tip of the bump is flat, the object can be achieved by rolling the cylinder. In the above example, the remaining conductive adhesive was scraped off every time the conductive adhesive was supplied to the bumps. However, this is not always the case, and the transfer (supply) is performed many times unless the properties of the conductive adhesive change. ) Can do it. The bump may be once contacted to avoid the recessed portion on the surface of the conductive adhesive, and then contact the bump of the next semiconductor chip. Further, in FIG. 1, the pattern of the conductive adhesive is described as a continuous layer of the conductive adhesive, but may be a dot shape corresponding to the position of the bump. The conductive adhesive supply method of the present invention can be realized by a conductive adhesive supply device that performs at least the steps described above. Such an apparatus may be an apparatus that only forms a layer of a conductive adhesive by itself, or may be provided alongside a chip mounter. In the above description, only the semiconductor chip is taken as the device to which the conductive adhesive is supplied, but the present invention is not necessarily limited to these, and can be applied to chip capacitors, chip resistors, and the like. Further, it can be applied to forming bumps on chip capacitors and chip resistors for high-density mounting.

[0018]

As described above, according to the present invention, the amount of the conductive adhesive to be used can be extremely reduced, and at the same time, the conductive adhesive using a solvent having a low boiling point can be used. Can be shortened.

[Brief description of the drawings]

FIGS. 1A to 1D are process cross-sectional views illustrating a method for supplying a conductive adhesive according to an embodiment of the present invention.

FIGS. 2A to 2C are process cross-sectional views illustrating a conventional conductive adhesive supply method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Plate 102 Conductive adhesive small amount supply apparatus 103 Patterned conductive adhesive layer 104 Conductive adhesive 105 Remaining conductive adhesive 106 Knife edge 107 Conductive adhesive part 201 Semiconductor chip 202 Bump 203 Plate 204 Shallow engraving 205 Squeegee 206 Conductive adhesive layer 207 Conductive adhesive part

Claims (8)

[Claims] 1. A method for forming a conductive adhesive in a predetermined shape on a bump surface of a device, comprising supplying a conductive adhesive to a surface of a plate in a predetermined pattern using a minute supply device. Forming a conductive adhesive portion having a predetermined thickness on the bump by contacting the conductive adhesive layer with a bump formed on a device. 2. The method according to claim 1, wherein the surface of the plate is flat or curved. 3. The method for supplying a conductive adhesive according to claim 1, wherein the device for supplying a small amount of the conductive adhesive has a storage section for sealing the conductive adhesive before application. 4. A method of supplying a conductive adhesive to a bump formed on a device, removing the conductive adhesive on a plate, and then supplying a new conductive adhesive in a pattern by a micro supply device. Item 4. A method for supplying a conductive adhesive according to Item 1. 5. An apparatus for forming a conductive adhesive having a predetermined shape on a surface of a bump of a device, wherein the conductive adhesive is supplied to the surface of a plate in a predetermined pattern to form a conductive adhesive layer. A supply device, means for contacting the bump formed on the device with the conductive adhesive layer, means for separating the bump from the conductive adhesive layer, and means for scraping off the remaining conductive adhesive with a knife edge; A supply device for a conductive adhesive, comprising: 6. The conductive adhesive supply device according to claim 5, wherein the surface of the plate is flat or curved. 7. The conductive adhesive supply apparatus according to claim 5, wherein the conductive adhesive minute supply apparatus has a storage section for sealing the conductive adhesive before application. 8. A chip mounter for forming a conductive adhesive of a predetermined shape on a bump surface of a device, wherein the conductive adhesive is supplied to the surface of a plate in a predetermined pattern to form a conductive adhesive layer. A micro-supply device, means for contacting the bump formed on the device with the conductive adhesive layer, means for separating the bump from the conductive adhesive layer, and means for scraping off the remaining conductive adhesive with a knife edge A chip mounter incorporating a conductive adhesive supply device, comprising: