JP2885974B2 - Method for producing tape for film carrier and method for producing film carrier - 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 of manufacturing a tape for a film carrier used for evaluating and mounting a high-frequency microwave device and the like, and a method of manufacturing a film carrier.

[0002]

2. Description of the Related Art As a conventional technique for forming a tape for a film carrier using a polyimide film, which is an insulating flexible substrate, a method of laminating a polyimide film and a foil using an adhesive shown in FIG. (Three-layer type), which is used for TAB (Tape Automated Bonding). In FIG. 6, 1 is an insulating flexible substrate made of, for example, a polyimide film, 17 is an epoxy or acrylic adhesive, and 16 is a conductor layer made of copper foil.

On the other hand, a two-layer type film carrier tape not using an adhesive shown in FIG. 7 is formed by a method in which a conductor layer 16 of a rolled copper foil or an electrolytic copper foil is joined to the insulating flexible substrate 1 by hot pressing. The thickness of the conductor layer 16 is generally 35 μm or more from the viewpoint of mechanical strength. Further, a method of directly sputtering copper or a method of sputtering copper after nickel or chromium is sputtered to improve the adhesion between the copper and the insulating flexible substrate 1 may be used. At this time, the thickness of the conductor layer 16 by sputtering is usually 0.01 μm to 0.1 μm. For the method by vapor deposition, a manufacturing method substantially similar to the method by sputtering is used.

As another method, for example, a two-layer tape is formed by coating a polyimide varnish on a copper foil having a thickness of, for example, 35 μm, removing the solvent by heating with a heater or the like, and drying and imidizing. is there.

As a system for mounting a bare chip semiconductor element or the like using a flexible wiring board, there is a film carrier for a high-frequency IC described in JP-A-2-34948 invented by the present inventors. This film carrier for high-frequency ICs has been improved for use in the high-frequency region. As shown in FIG. 8, a coplanar impedance-matched input / output impedance of a chip element and a characteristic impedance of a case or another wiring board are used. Waveguide 1
1 is formed on the surface of the insulating flexible substrate 1 and the lengths of the inner lead portions 6 and the outer lead portions 7 are shortened, all of which are manufactured by a photolithography process. here,
5 is a bump, 8 is a conductor film for a waveguide, 9 is a wiring for a DC power supply, and 10 is an opening for a chip element.

[0006]

However, in the case of the three-layer type using the adhesive 17 shown in FIG. 6, the opening of the film can be formed by mechanical punching using a mold, but the size of the film can be processed. Is 0.4 mm square or more, and there is a problem that it is difficult to form a via hole (less than 0.4 mm square) for connecting between wirings necessary for forming on both sides of the film. Further, it is conceivable to chemically form the opening 10 of the insulative flexible substrate 1. However, since the adhesive 17 and the etchant for the insulative flexible substrate 1 are different from each other, there is a disadvantage that the chemical etching process becomes complicated. there were. Furthermore, since the heat resistance of the adhesive 17 is low, there is a problem that the stability of adhesion at high temperatures is poor.

[0007] In a two-layer type film carrier tape as shown in FIG. 7 using a sputtering method or the like, a material having good adhesion such as nickel or chromium is sputtered on the insulating flexible substrate 1 in advance, and then the film is continuously formed. Since copper is sputtered, a different etching solution is required when forming a wiring pattern, and there is a problem that the number of steps increases. Further, there is a problem that the insulating flexible substrate 1 is easily curled at the time of sputtering.

Further, in the case of a two-layer type film carrier tape using a casting method, it is necessary to remove the solvent contained in the varnish, so that it is difficult to form the conductor layers 16 on both sides of the insulating flexible substrate 1. There was a disadvantage. Further, in the tape for a film carrier formed by the hot press method, the adhesive strength between the insulating flexible substrate 1 and the conductor layer 16 such as a copper foil is smaller than that using the adhesive 17, so that a fine conductor tape is formed. There has been a problem that the pattern size is restricted in forming the pattern.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to produce a tape for a film carrier which has a high yield, a high adhesion strength, and can easily form a conductor film on both sides. A method and a method for manufacturing a film carrier.

[0010]

According to a method of manufacturing a tape for a film carrier according to the present invention, a surface of an insulative flexible substrate is roughened, and then a base conductor film is formed by an electroless plating step. That is, the surface of the insulating flexible substrate is roughened by reactive ion etching using an oxygen gas or the like. Subsequently, a base conductor film is formed by an electroless plating step to obtain a two-layer type film carrier tape.

In the method for producing a film carrier according to the present invention, the film carrier tape is used.
A high frequency electrode, a bias supply electrode,
Forming a grounding electrode and a lead connected to each of these electrodes by electrolytic plating, forming a protruding metal at the tip of the lead connected to each of the electrodes, The opening is formed by etching.

[0012]

According to the present invention, the surface of the insulating flexible substrate can be finely roughened by reactive ion etching with oxygen gas or the like, and the adhesion between the insulating flexible substrate and the underlying conductor film formed by electroless plating can be improved. Can be improved. That is, due to the surface roughening, the adhesion area between the insulating flexible substrate surface and the underlying conductor film increases,
By improving the anchor effect, the adhesion between the insulating flexible substrate and the underlying conductor film is improved. Using this film carrier tape, openings are formed by etching to obtain a film carrier.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an embodiment in the case of forming a base conductor film of the present invention. For example, contaminants such as fats and oils and dust on the surface of the insulating flexible substrate 1 made of a polyimide film are sufficiently removed with an organic solvent such as acetone, an acid or an alkaline cleaning solution (FIG. 1A). Then, the surface roughened layer 2 of the insulating flexible substrate 1 is formed by reactive ion etching (RIE) using oxygen gas, a mixed gas of oxygen gas and carbon tetrafluoride gas (FIG. 1).
(B)). Specifically, surface roughening is performed for about 10 minutes at a high-frequency effective power of 50 W. Next, a Pd nucleation film 3 for electroless copper deposition is formed (FIG. 1C). Here, palladium (P
d) is formed on the surface of the insulating flexible substrate 1.
Then, the underlying conductor film 4 is formed by an electroless copper plating process (FIG. 1D). The film thickness at this time is about 0.01 to
It is 0.05 μm.

Next, annealing is performed in a nitrogen atmosphere. Specifically, it is performed at about 300 ° C. for 30 minutes. Temperature rise is 300 ° C
Until about 2 hours, the cooling is naturally cooled, all in a nitrogen atmosphere. Thereafter, a film carrier tape is completed by applying a copper film 4 'to a thickness of about 1 to 2 μm on the underlying conductor film 4 by electrolytic plating (FIG. 1 (e)).
FIG. 2 shows a process chart of the embodiment of FIG.

Here, an experimental example regarding the adhesion between the base conductor film 4 and the insulating flexible substrate 1 in the film carrier tape manufactured by using the present invention will be described with reference to FIG.

FIG. 5 shows a conductor pattern of an electroless plating film when a polyimide film is used as the insulating flexible substrate 1 and its surface is subjected to reactive ion etching with an oxygen gas (straight line A) or not (straight line B). And the results of evaluating the 90 ° peel strength of the polyimide film and the polyimide film (based on JIS-C-6471-B method). For reference, the results of evaluating a two-layer type sample (straight line C) obtained by hot pressing a copper foil and a polyimide film are also shown. In the peel strength table, a sample in which a wiring pattern having a width of 90 to 350 μm and a length of 1 mm was formed on a polyimide film was used. The peel strength shown by the straight line (A) is about 60 times that of the straight line B and about 2 times that of the straight line C.
The strength was more than doubled.

Next, an embodiment in which a film carrier is manufactured using the tape for a film carrier manufactured according to the present invention will be described with reference to FIG. FIGS. 3A to 3D show the first embodiment of FIG.
Same as (d). In FIG. 3, the illustration of the annealing step and the step of thickening the copper film by electrolytic plating are omitted. Next, after the first photoresist film 12 is applied on the base conductor film 4, a high-frequency electrode, a bias supply electrode, a ground electrode, and leads connected to these electrodes are patterned by a photolithography process ( FIG.
(E)). Further, an electrolytic plating film 13 such as the above-mentioned electrode is thickened by electrolytic plating (FIG. 3F). Specifically, it is configured using a metal material such as Cu, Ni, Au, Sn, Rh, and Co.

After the first photoresist film 12 is removed, a second photoresist film 14 is applied on the surface on which the above-mentioned electrodes and the like are located, and a bump made of a protruding metal is formed on the tip of the lead by the same photolithography process as described above. A bump 5 (for example, gold) is formed by forming an opening pattern for use and thickening it by electrolytic plating (FIG. 3G). Next, the second
After removing the photoresist film 14, a third photoresist 15 is applied to the surface opposite to the surface on which the high-frequency electrode, the bias supply electrode, and the ground electrode, and the leads connected to these electrodes are formed. After forming a pattern for the opening 10 for mounting a device or the like by a photolithography process (FIG. 3 (h)), the opening 10 is formed by chemically etching the insulating flexible substrate 1 (FIG. 3 ( i)). Finally, the unnecessary third photoresist film 1
5. The underlying conductor film 4 is removed to complete the film carrier (FIG. 3 (j)).

In the embodiment, a polyimide film is used as the insulating flexible substrate 1. However, an epoxy film, a polyester film or the like may be used.

FIG. 4 shows a process chart of the embodiment of FIG.

[0021]

As described above, in the method for manufacturing a tape for a film carrier and the method for manufacturing a film carrier according to the present invention, a surface of an insulative flexible substrate is roughened and then a base conductive film is formed by electroless plating. Since the base conductor film does not peel off in the photolithography step or the electrolytic plating step of the step of manufacturing the film carrier, furthermore, even in the etching of the insulating flexible substrate using a strong alkaline solution,
The underlying conductor film is not damaged. Therefore, by using the manufacturing method of the present invention, a film carrier is provided in which the adhesion strength between the insulating flexible substrate and the underlying conductor film is increased, the peeling of the underlying conductor film during the production process is prevented, and the production yield is improved. it can.

In addition, since the adhesion strength between the polyimide film and the underlying conductor film is improved, it is possible to make the pattern finer.

Further, since the electroless plating method is used, a wiring pattern can be formed on both sides of the insulating flexible substrate, and a pattern can be formed on both sides, and a via for connection between wiring patterns can be formed. Become.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a method for producing a film carrier tape of the present invention.

FIG. 2 is a process chart of manufacturing a film carrier tape of the present invention.

FIG. 3 is a cross-sectional view showing one embodiment of the method for producing a film carrier of the present invention.

FIG. 4 is a manufacturing process diagram of the film carrier of the present invention.

FIG. 5 is a diagram showing the peel strength between a base conductor film of the present invention and a polyimide film.

FIG. 6 is a sectional view of an insulating flexible substrate using a conventional adhesive.

FIG. 7 is a cross-sectional view of a conventional insulating flexible substrate not using an adhesive.

FIG. 8 is a schematic perspective view showing an example of a conventional film carrier.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating flexible board 2 Surface roughening layer by RIE 3 Pd nucleation film for electroless copper deposition 4 Base conductor film 5 Bump 6 Inner lead part 7 Outer lead part 8 Conductor film for waveguide 9 DC power supply wiring 10 Opening 11 Coplanar waveguide 12 First photoresist film 13 Electroplating film 14 Second photoresist film 15 Third photoresist film 16 Conductive layer 17 Adhesive

Claims (2)

(57) [Claims] 1. A semiconductor element comprising an insulating flexible substrate, a high-frequency electrode, a bias supply electrode, and a grounding electrode formed on the insulating flexible substrate, and leads connected to these electrodes. In the method of manufacturing a tape for a film carrier for mounting, a step of surface roughening the entire surface of the insulating flexible substrate by a reactive ion etching method, and then forming the base flexible conductive film by an electroless plating method. A method for producing a tape for a film carrier, comprising a step of forming the tape on a substrate. 2. A high-frequency electrode, a bias supply electrode, and a grounding electrode, on the base conductor film formed on the insulating flexible substrate, using the tape for a film carrier according to claim 1. Forming a connected lead by electrolytic plating, forming a protruding metal at the tip of the lead connected to each electrode, and forming an opening in the insulating flexible substrate by etching. And a process for producing a film carrier.