JPH05326526A - Composite film and formation of solder bump using the same - Google Patents

Abstract

PURPOSE:To provide a composite film, which is capable of forming solder bumps on a semiconductor element, electrical and electronic components, an electric circuit and the like with high accuracy even at a narrow pitch and easily, and a method of forming the solder bumps using this film. CONSTITUTION:A solder 2 is held in a composite film in such a way that it is made to penetrate an insulative film 1 consisting of a polyimide resin or the like front the surface to the back surface and protrudes from the surface on at least one side of the surfaces and this solder 2 is held in a state that it can be separated from the film 2 by heating and melting. It is desirable that the formation of a through hole in the film 1 is performed by a laser processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite film for forming solder bumps used for connecting and mounting various parts such as semiconductor devices, printers, recording devices, display devices, electric parts and electric circuits, and this film. The present invention relates to a solder bump forming method using

[0002]

2. Description of the Related Art With the recent development of the semiconductor industry, electronic devices have become thinner, smaller and lighter, and it has been desired to mount various electric circuit components on a substrate having a constant area with high density. In particular, improvements have been promoted for miniaturization such as surface mounting of various functional parts built into OA equipment. The demand for high-density mounting has become more severe, and a terminal pitch at the time of mounting is 0.3 mm or less.

However, in such mounting, bumps are usually used by forming a solder paste by printing or the like as connection terminals at the time of mounting, and the solder bridge between the printed solder bumps becomes smaller as the terminal pitch becomes narrower. Is more likely to occur, and the reliability of electrical connection is reduced. Further, in the printing method, since the amount of solder varies widely, it is difficult to form solder bumps with high accuracy.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of various problems in the above-mentioned conventional solder bump forming technique, and has a narrow pitch in semiconductor elements, electric / electronic parts, electric circuits and the like. Another object of the present invention is to provide a composite film that can form solder bumps used for connection and contact with high accuracy and easily, and to provide a solder bump forming method forming method using this film.

[0005]

The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, use a composite film having a specific structure for holding the solder for bumps in a meltable and detachable state. As a result, they have found that solder bumps can be easily formed, and completed the present invention.

That is, the present invention provides a composite film which holds the solder for bumps in a meltable and detachable state so as to penetrate the front and back surfaces of the insulating film and project from at least one surface. is there.

Further, according to the present invention, the composite film according to claim 1 is placed on a semiconductor element, an electric circuit, or an electric circuit component, and the projecting solder portion is brought into contact with the transferred portion and then heated. The present invention provides a method for forming solder bumps, which comprises melting and transferring the held solder.

A composite film of the present invention and a solder bump forming method using the same will be described below with reference to the drawings.

FIG. 1 is an enlarged sectional view showing an example of the composite film of the present invention.

As is apparent from FIG. 1, in the composite film of the present invention, the solder 2 is penetrated through the front and back surfaces of the insulating film 1.
This solder 2 is projected to one surface (upper side in the drawing) and is held so as to be melted and separated by heating. The protruding shape of the solder 2 from the insulating film 1 is not particularly limited, but in order to reliably melt transfer to a semiconductor element as an adherend, an electric circuit, or an electric circuit component, a mushroom shape as illustrated is used. Preferably.

The insulating film 1 has electrical insulation and may be heat resistant at a temperature at which the solder to be held melts. Specifically, thermosetting resins such as polyester resin, epoxy resin, urethane resin, polystyrene resin, polyethylene resin, polyamide resin, polyimide resin, ABS resin, polycarbonate resin, silicone resin, and fluorine resin. Any thermoplastic resin can be used. Among these resins, a resin having transparency is preferable from the viewpoint of ease of alignment when transferring the solder bumps, and a polyimide resin is preferably used from the viewpoint of heat resistance and mechanical strength. Further, the thickness of the insulating film 1 can be arbitrarily selected according to the amount (volume) of solder bumps to be transferred and formed.

FIG. 2 is an enlarged sectional view showing another example of the composite film of the present invention, in which the solder 2 held on the insulating film 1 is projected on the front and back surfaces of the film. The protruding shape is a so-called rivet shape. By forming in this way, it is possible to prevent the solder from falling off from the composite film of the present invention before use.

FIG. 3 is an enlarged sectional view showing another example of the composite film of the present invention. A metal layer 3 as a support layer is formed on one surface of the insulating film 1, and the metal layer 3 acts so that the held solder 2 does not drop off. The metal layer 3 is preferably made of a material that does not melt and mix with the solder so that only the solder 2 is transferred when the solder 2 is melt-transferred, and is preferably formed of a metal having poor wettability with respect to the solder. Examples of such a metal include nickel and chromium.

FIG. 4 is a sectional view showing an example of a solder bump forming method using the composite film of the present invention shown in FIG.

As shown in FIG. 4A, the protrusion of the solder 2 in the composite film of the present invention is used as an adherend, for example,
The electrode portion 5 on the external circuit 4 is aligned and brought into contact. At this time, it is preferable to provide an alignment hole or a jig hole in the composite film of the present invention in order to perform the alignment accurately. It is preferable to coat the surface of the electrode portion 5 with a metal (for example, gold) having a good wettability with respect to the solder, because the solder bump can be formed with high precision. Next, by heating the composite film of the present invention with a hot plate or a heating furnace, the solder 2 held in the insulating film 1 is melted and transferred to the adherend (electrode part 5), and the soldering is performed as shown in FIG. The substantially spherical solder bumps 12 (solder balls) as shown in B) are formed on the adherend. The same applies when a semiconductor element is used as the adherend instead of the external circuit 5.

FIG. 5 is an enlarged sectional view showing each manufacturing process for obtaining the composite film of the present invention shown in FIG.

Only the insulating film 1 of the laminated film in which the insulating film 1 is provided on the metal layer 3 made of a copper foil or a copper plate as shown in FIG. 5A is mechanically processed, laser processed, or light processed. A hole 6 reaching the surface of the metal layer 3 as shown in FIG. 5B is formed by chemical etching or the like. As a method of forming the holes 6, it is preferable to use an ultraviolet laser such as an excimer laser having an oscillation wavelength in the ultraviolet region from the viewpoints of fine workability and the degree of freedom of the processed shape.

Next, electrolytic plating is performed using the metal layer 3 as an electrode to fill the solder 2 in the hole 6 formed as shown in FIG. 5 (C). At this time, the plating of the solder 2 is performed until it projects from the surface of the insulating film 1. The protruding shape and size of the solder 2 can be appropriately set depending on the bump shape to be transferred and the size of the electrode portion of the adherend. Further, the size (volume) of the solder bump to be transferred and formed is equal to that of the hole portion 6.
Can be adjusted according to the size of the film and the thickness of the insulating film 1.

Finally, if necessary, the metal layer 3 can be removed by a known etching treatment to obtain the composite film of the present invention shown in FIG. 5 (D). After that, the above-mentioned alignment holes and jig holes may be provided by mechanical processing, laser processing, optical processing, chemical etching processing, or the like.
In addition, when the metal layer 3 is not removed, the composite film having the structure shown in FIG. 3 can be obtained.

FIG. 6 is an enlarged sectional view showing each manufacturing process for obtaining another composite film of the present invention shown in FIG.

6A and 6B are the same steps as FIGS. 5A and 5B, and FIGS. 6D and 6E are the same steps as FIGS. 5C and 5D. Is. The manufacturing method of FIG. 6 is characterized by the addition of the step of FIG.
Is formed on the insulating film 1, and then a recess (for example, a hemisphere) as shown in the drawing is formed on the surface of the metal layer 3 exposed by electrolytic corrosion or polishing. By processing in this manner, the solder retained in the finally obtained composite film has a shape protruding on both sides.

[0022]

As described above, the composite film of the present invention is
Since the solder for bumps of a desired size is held so that it can be melted and removed, it is possible to transfer solder bumps accurately and easily to the electrodes of high-density semiconductor elements, electrical parts, electrical circuits, etc. it can. Therefore, as compared with the conventional solder paste printing method, solder bumps can be formed even on terminals with a narrow pitch, and the amount of transferred solder varies little.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing an example of a composite film of the present invention.

FIG. 2 is an enlarged cross-sectional view showing another example of the composite film of the present invention.

FIG. 3 is an enlarged cross-sectional view showing another example of the composite film of the present invention.

FIG. 4 is an enlarged cross-sectional view showing an example of a transfer bump forming method using the composite film of the present invention.

5A to 5D are enlarged cross-sectional views showing respective manufacturing steps for obtaining another composite film of the present invention.

6A to 6E are enlarged cross-sectional views showing respective manufacturing steps for obtaining another composite film of the present invention.

[Explanation of symbols]

 1 Insulating Film 2 Solder 3 Metal Layer 4 External Circuit 5 Electrode Section 6 Hole Section 12 Solder Bump

Claims (3)

[Claims] 1. A composite film that holds solder for bumps in a meltable and detachable state so as to penetrate the front and back surfaces of an insulating film and project from at least one surface. 2. The composite film according to claim 1, wherein a metal layer is formed on one surface of the insulating film. 3. The composite film according to claim 1 is placed on a semiconductor element, an electric circuit, or an electric circuit component, and the projecting solder portion is brought into contact with the transferred portion and then held by heating. A method for forming solder bumps, which comprises melting and transferring solder.