JP2643884B2 - Bump forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a bump, and more particularly to a method for connecting a semiconductor chip to a flip chip or a TA.
The present invention relates to a method for forming a bump used to connect an electrode of a semiconductor chip to an electrode of a circuit board or a TAB lead when performing B (Tape Automated Bonding) connection.

[0002]

2. Description of the Related Art Conventionally, as a bump forming method of this kind, there has been a method described in, for example, JP-A-4-10542.

FIGS. 4A and 4B are sectional views showing a conventional bump forming method. First, an electrode 36 is formed on a circuit board 37 as shown in FIG. A metal-containing tape 35 is set on the electrode 36. The metal-containing tape 35 includes three layers of a tape base 32 made of a material such as polyimide, a bump material 33 formed by adhesion on the tape base 32, and an electrode 36 and an adhesive metal 34 having adhesiveness.

[0004] The metal-containing tape 35 is pressed by the punch 30, and as shown in FIG. 4 (b), the bump material 33 adheres to the surface of the electrode 36 with the adhesive metal 34.
The bump 38 is formed. The tip of the punch 30 is pressed at a constant pressure to prevent the tape base 32 from being cut or the electrode 36 from being cracked.
An elastic body 31 is formed.

The bump material 33 is formed by tapering metal particles with a resin, and the adhesive metal 34 on the surface is formed by depositing a low-melting-point metal such as indium by vapor deposition.

FIG. 5 shows a bump material 33 after partial bump formation.
FIG. The circled portions in the figure show the portions where the bump material 33 has been transferred by pressing with the punch 30 at the portions where the bumps were formed. By pressing with the punch 30 in this manner, a part of the bump material 33 is separated from the tape base 32 and formed as a bump 38 on the electrode 36, and the surrounding part remains.

[0007]

However, in this conventional bump forming method, a bump material in which metal particles are taped with a resin is pressed with a punch, and the bump is formed with an adhesive metal formed on the surface of the bump material. Therefore, there is a problem that the bump material around the pressed portion is also transferred, and the amount of the bump is not constant, and a stable connection cannot be obtained at the time of flip chip connection. Furthermore, since only bumps of the tape-shaped material are pressed and formed as bumps, the remaining portion around the transferred portion is completely wasted and the cost of the material increases. there were.

As a method of forming a constant amount of bumps, as shown in Japanese Patent Application Laid-Open No. 4-120735, a bump material such as tape-like gold is punched out using a punch and a die, and the bumps are pressed or the like. There is also a method of forming the material, but also in this method, the material remaining around the punched portion is wasted, and the cost is increased.

As described above, in the prior art, if a stable amount of bumps is to be formed, an extra material is required in addition to the amount of the bumps, which is uneconomical.

[0010]

A bump forming method according to the present invention is directed to a tape-shaped bump provided on one surface of a protective tape for conveyance.
Using a cutting tool to remove the protective tape
Make a linear cut in the width direction of the protective tape at the pitch
And has an inelastic head on the other surface of the protective tape
Apply a pressing tool to the bump material in order from the end
Transfer to the electrode of the substrate or semiconductor chip and apply while heating.
Pressing and joining to form a bump.

According to the present invention, as described above, the tape-shaped bump material is cut into a predetermined size in order from the end, and the bumps are formed on the electrodes of the circuit board. No extra material is required except for the parts. Therefore, a fixed amount of bumps can be formed stably without increasing the cost.

[0012]

Next, the present invention will be described with reference to the drawings.

FIGS. 1A to 1E are process side views showing one embodiment of the bump forming method of the present invention. First, FIG.
(A) shows a tape-shaped bump material 2 used in the present invention. For example, a protective tape 1 made of a material such as polyimide is adhered to one side of a bump material 2 made of a metal material such as gold or solder. However, the adhesion of the protective tape 1 is such that the bump material 2 can be easily peeled off by the force when the bump material 2 is joined to the electrodes 8 of the circuit board 7. For example, in addition to using an adhesive having a low adhesive strength, there is a bonding with a thermoplastic resin which loses the adhesive strength when heated, and a bonding with a UV resin whose adhesive strength becomes weak when exposed to ultraviolet rays. After the bump material 2 is sequentially supplied as the bump 6, the protective tape 1 is wound up by a reel or the like, and is also used for conveying the bump material 2. The bump material 2 is wound around a reel or the like in a state where the protection tape 1 is adhered, and a necessary amount is conveyed by winding the protection tape 1.

When the required amount of the bump material 2 has been transported, FIG.
By moving the cutting tool 4 in the direction of the arrow as shown in (b), the required length of the bump material 2 for the bump 6 is cut. At this time, a material holder 3 is provided on the protective tape 1 side to prevent deformation of the bump material 2 and to perform reliable cutting.
Is arranged. The cutting tool 4 is a sharp blade and cuts the bump material 2 at normal temperature or while being heated. For cutting the bump material 2, other cutting means, for example, a laser or the like may be used in addition to using the cutting tool 4.

FIG. 1C shows the bump material 2 and the protective tape cut to a predetermined length.

Next, as shown in FIG. 1D, the bump material 2 cut to a predetermined length is positioned on the electrodes 8 of the circuit board 7, and then the protective tape 1 is pressed by the pressing tool 5. Pressure is applied from above to form the bumps 6 on the electrodes 8 on the circuit board 7. At this time, the bump material 2 is peeled off from the protective tape 1, and as shown in FIG.
Is in a state where only the bumps 6 are formed.

When the bump material 2 is pressed, stronger bonding can be obtained by applying ultrasonic waves to the pressing tool 5 or heating the circuit board 7.

The bump material 2 may be, for example, a metal formed into a foil having a thickness of several tens of μm by plating, a metal rolled into a tape having a thickness of about 50 μm and a width of about 100 μm, or a wire having a diameter of about 100 μm. A metal wire of about several tens μm to 100 μm is used. The material such as the metal wire is adhered to the protective tape 1 and wound on a reel or the like, and the bump material 2 is supplied. If the bump material 2 is a hard material and a large cutting force is required to cut the bump material 2 and the protection tape 1 may be cut at the same time, the width of the protection tape 1 may be reduced. Be wider than width. Even if the protective tape 1 is cut by the width of the bump material 2, the surrounding portion of the protective tape 1 remains and the bump material 2 is cut.
Transfer and winding on a reel can be performed without any problem.

FIG. 2 shows the bump material 2. The dotted line is the bump material 2 after being cut from the protective tape 1 for forming the bump. As shown in the figure, bump material 2
Since it is cut off from the end, there is no wasted part and it is economical. In the above embodiment, the formation of the bumps on the electrodes 8 of the circuit board 7 has been described. However, the formation of the bumps on the electrodes of the semiconductor chip can be performed in a similar manner.

Next, an apparatus for forming the bump 6 using the above-described bump forming method will be described.

FIG. 3 is a schematic view showing an example of use of the present invention. Protective tape 1 and bump material 2 are supplied on supply reel 11
And wound on the take-up reel 12. First, the position of the electrode 8 on the circuit board 7 is recognized by the recognition camera 13, and the stage 14 moves and is positioned below the pressing tool 5. The bump material 2 is made of a material holder 3
Is cut to a predetermined length by the cutting tool 4, and is conveyed under the pressure tool 5 by the rotation of the take-up reel 12. When the position of the bump material 2 and the position of the electrode 8 are matched, the cut bump material is pressed and pressed by the pressing tool 5 while applying or heating ultrasonic waves. Thereafter, the same operation is sequentially repeated, and bumps are formed.

[0022]

As described above, according to the bump forming method of the present invention, the bump material 2 adhered to the protective tape 1 such as polyimide is cut into a predetermined length one by one from the end.
Since the bonding to the electrode 8 of the circuit board 7 is performed, a useless portion is not generated in the bump material 2 and a certain amount of the bump 6 can be supplied. Further, since the bonding of the bump material 2 to the electrode 8 of the circuit board 7 is performed by ultrasonic pressure bonding or thermocompression bonding, an adhesive material for bonding is not required. Therefore, bumps used for connecting the semiconductor chip and the circuit board can be formed in a stable amount at a lower cost.

[Brief description of the drawings]

FIGS. 1A to 1E are process diagrams showing one embodiment of the present invention.

FIG. 2 is a view showing a bump material of the embodiment of FIG. 1;

FIG. 3 is a schematic view showing an example of use of the present invention.

FIGS. 4A and 4B are cross-sectional views showing an example of the related art.

FIG. 5 is a top view showing a conventional bump material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Protective tape 2 Bump material 3 Material holder 4 Cutting tool 5 Pressure tool 6 Bump 7 Circuit board 8 Electrode 11 Supply reel 12 Winding reel 13 Recognition camera 14 Stage 30 Punch 31 Elastic body 32 Tape base 33 Bump material 34 Adhesive metal 35 Metal-containing tape 36 Electrode 37 Circuit board 38 Bump

Claims (4)

(57) [Claims] 1. A tape-shaped bump material provided on one surface of a protective tape for conveyance is cut using a cutting tool to form the protective tape.
Leaving a straight line in the width direction of the protective tape at a constant pitch.
Make a notch and attach an inelastic head to the other surface of the protective tape.
The bump material from the end by applying a pressure tool with
Transfer to the electrodes of the circuit board or semiconductor chip in sequence and heat
A method of forming a bump, wherein the bonding is performed while applying pressure. 2. The bump forming method according to claim 1, wherein the bump material is a metal foil formed by plating, a rolled metal, or a metal wire. 3. The bump forming method according to claim 1, wherein the width of the bump material is equal to or smaller than the width of the protective tape. 4. The bump forming method according to claim 1, wherein an ultrasonic wave is applied or heated when the cut bump material is pressure-bonded.