JP3812280B2 - Method for producing tin-solder two-color plating TAB tape - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a tin-solder two-color plating TAB tape used in a TAB (Tape Automated Bonding) method, which is one of mounting methods of semiconductor elements such as IC and LSI.
[0002]
[Prior art]
LSIs are becoming more highly integrated, faster, and more functional, and the pattern leads of LSI packages to be mounted are becoming finer and the number of pins is increasing. TCP (tape carrier package) using a TAB tape is used as an LSI package corresponding to this.
[0003]
Usually, after forming a copper wiring pattern on the TAB tape, tin plating is performed by an electroless method in order to improve the bonding property with the LSI bump, but the tin plating thickness is 0.3 to 0.6 μm. When the sealing resin is cured after the LSI is bonded, an intermetallic compound of copper and tin is formed, so that the solderability between the outer lead and the printed board is deteriorated. Therefore, tin-solder two-color plating TAB tape with 6 to 10 μm thick electrosolder plating is used instead of pre-soldering the printed circuit board for the inner leads and electroless tin plating for the inner leads. ing.
[0004]
FIG. 3 shows a configuration example of a tin-solder two-color plating TAB tape 1 conventionally used. The TAB tape 1 includes an insulating film 2 made of a long and thin insulating film tape and a lead 3 in which a copper lead having a predetermined pattern formed on the upper surface thereof is plated. The insulating film 2 is a flexible film made using polyimide, polyester, or the like. The lead 3 is patterned by bonding the copper foil to the upper surface of the insulating film 2 and then subjecting the inner lead 4 and the outer leads 5 connected to the inner leads 4 to photo etching according to the lead pattern. It is formed.
[0005]
Furthermore, a device hole 6 for accommodating a semiconductor element is opened at a substantially central portion of the insulating film 2. Further, on both sides of the insulating film 2, a sprocket hole 7 for performing tape conveyance and positioning is provided, and an outer hole 8 for outputting an electric signal corresponding to the outer lead 5 is provided. The device hole 6, the sprocket hole 7 and the outer hole 8 are formed by punching. A predetermined pad of the outer lead 5 is connected to a test pad 9 for performing an operation test or the like of the semiconductor element.
[0006]
As a conventional method for manufacturing a tin-solder two-color plating TAB tape, a device hole 6, a sprocket hole 7 and an outer hole 8 are opened in an insulating film 2 coated with an adhesive by punching, and this adhesive is applied to the surface. Laminate copper foil with the roughened surface facing. Since the roughened surface of the copper foil exposed to the device hole 6 is a surface connected to the LSI bump, polishing is performed by a chemical polishing method.
[0007]
Next, a photosensitive resist is applied to a predetermined region on the surface of the copper foil. After drying the photosensitive resist, the photosensitive resist is exposed through a photomask. Next, development is performed to form a photoresist layer having a predetermined pattern. The inner lead 4 and the outer lead 5 are formed by performing etching using this photoresist layer as a mask. The inner leads are plated with tin electrolessly for bonding to the LSI bumps, and the outer leads 5 are subjected to electric solder plating in order to improve the solderability to the printed circuit board.
[0008]
A plating method for the inner lead 4 and the outer lead 5 will be described below. After the lead 3 is formed, a masking resist is applied only to the inner lead 4, and only the outer lead 5 is subjected to electric solder plating. After the masking resist is peeled off, the inner lead 4 is subjected to tin plating by an electroless method. The electroless tin plating treatment is formed by applying plating and washing with water after the pickling pretreatment.
[0009]
[Problems to be solved by the invention]
However, according to the conventional method for manufacturing a tin-solder two-color plating TAB tape, when electroless tin plating is applied to the inner lead 4, the outer lead is immersed in an acidic aqueous solution having a soft etching property by a pretreatment pickling treatment. There is a problem that the solder plating applied to the lead 5 dissolves by pitting depending on the plating composition (when the Sn content is high) and deteriorates the solderability with the printed circuit board.
[0010]
Accordingly, an object of the present invention is to provide a method for manufacturing a tin-solder two-color plating TAB tape that solves the above-described problems and prevents the occurrence of pitting of solder plating applied to the outer lead in the pickling process of electroless tin plating. It is to provide.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows.
[0012]
(1) In the first aspect of the present invention, after forming a wiring pattern of copper leads on a flexible insulating film, only the inner leads are masked, and the outer leads are subjected to electric solder plating, and a masking agent is applied. In the method of manufacturing a tin-solder two-color plating TAB tape in which electroless tin plating is applied to the inner lead after peeling, the electroless tin plating composition of the outer lead is set to Sn 60 to 70%, and then the electroless tin is applied to the inner lead. It is characterized by plating.
[0013]
(2) The invention according to claim 2 is characterized in that electroless tin plating is applied to the inner lead by 0.5 to 0.6 μm.
[0014]
(3) In the invention according to claim 3, the solder plating composition of the outer lead after the electroless tin plating is made to be Sn 80 to 90% by substitution deposition of tin plating. It is a feature.
[0015]
The present invention will be described with reference to the form of FIG. 3. After forming the inner leads 4 and the outer leads 5 on the surface of the flexible insulating film 2 (FIGS. 1A and 1B), the inner leads 4 are formed. A masking resist is applied only to the inner lead (FIG. 1 (c)), and only the outer lead 5 is subjected to electric solder plating (FIG. 1 (d)). After the masking resist is peeled off (FIG. 1 (e)), an inner lead is formed. In the method of manufacturing a tin-solder two-color plating TAB tape in which tin plating is performed on the outer lead 4 by electroless method (FIG. 1 (f)), the outer lead is controlled by controlling the solder plating composition applied to the outer lead 5. On the premise that pitting occurring in the solder plating of 5 can be prevented, first, the electric solder plating composition of the outer lead 5 is set to Sn 60 to 70%. Those (FIG. 1 (d)). Thus, by reducing the Sn content, the plating composition does not dissolve by pitting.
[0016]
Furthermore, the outer lead 5 and the inner lead subjected to the solder plating are subjected to electroless tin plating, for example, 0.5 to 0.6 μm (FIG. 1 (f)). Pitting dissolution of the plating composition is very small, so that solderability does not deteriorate.
[0017]
On the other hand, the solder plating composition of the outer lead is Sn 80 to 90%, which is a composition with good solderability, by substitution deposition of tin plating (FIG. 1 (g)). That is, the outer lead is subjected to solder plating with a composition Sn 80 to 90% with good solderability, and the inner lead is also electroless tin-plated to improve the bonding property with the IC chip. Applied.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of a method for producing a tin-solder two-color plating TAB tape according to the present invention will be described with reference to FIG.
[0019]
First, the device hole 6, the outer hole 8, and the sprocket hole 7 are respectively formed in the insulating film 2 made of polyimide coated with an adhesive by punching. Next, a copper foil is laminated on the surface of the insulating film 2 (FIG. 1A). Subsequently, a photoresist is applied to the surface of the copper foil with a predetermined thickness and dried. Thereafter, a photomask having a predetermined pattern is arranged on the photoresist, and the photoresist is exposed by irradiating light from the side opposite to the photoresist side of the photomask. Thereafter, the photoresist is developed, and a copper foil exposed portion is formed in the photoresist to form a predetermined photoresist pattern on the surface of the copper foil. Then, the copper foil is etched using the photoresist pattern as a mask, a lead 3 having a predetermined wiring pattern having inner leads 4 and outer leads 5 is formed on the surface of the insulating film 2, and the photoresist pattern on the wiring pattern is removed. (FIG. 1B).
[0020]
In forming the plating on the inner lead 4 and the outer lead 5, a masking resist was applied to the inner lead 4 (FIG. 1 (c)), and the outer lead 5 was subjected to electric solder plating (FIG. 1 (d)). The conditions for the electric solder plating are a borofluoride bath (Unicon Tin Bright) manufactured by Ishihara Pharmaceutical Co., Ltd., and the composition of the solution is tin borofluoride concentration of 60 to 90 g / L, lead borofluoride concentration of 10 to 40 g / L, Borohydrofluoric acid concentration is 100 g / L, formalin concentration is 10 m / L, brightener UTBNo. 1 concentration is 40 m / L, brightener UTBNo. 2 The concentration is 60 m / L, the temperature is 17 ° C., the current density is 3.5 A / dm ² , the film thickness is 5.0 to 6.0 μm, and the plating film composition is the concentration of tin borofluoride as a plating bath component By changing the ratio of lead and borofluoride concentration, Sn 60%, 70%, 80% and 90% solder plating samples were prepared.
[0021]
Thereafter, the masking resist applied to the inner lead of each sample subjected to the solder plating is peeled off with a solvent (FIG. 1 (e)), and after the pickling pretreatment, electroless tin plating is applied to the inner lead 4 by 0.5 to 0.6 μm was applied (FIG. 1 (f)). The pickling pretreatment is a potassium persulfate-based AD485 (manufactured by Meltex) in the treatment solution, and the solution composition is AD485 concentration 50 g / L + 5% sulfuric acid is added and treated at room temperature for 30 seconds. The electroless tin plating was performed at 70 ° C. for 3 minutes using 580M manufactured by Ishihara Yakuhin as the plating solution.
[0022]
FIG. 2 shows the result of pitting occurrence in which 200 outer leads 5 subjected to solder plating after electroless tin plating were observed. From FIG. 2, the outer lead produced with a solder plating composition of Sn 60 to 70% was produced with solder plating composition of Sn 80 to 90% while no occurrence of pitting was observed after electroless tin plating. Pitting was observed on the outer lead.
[0023]
In addition, it was confirmed that the solder plating composition of the outer lead after the electroless tin plating is a plating film composition with a good solderability of Sn 80 to 90% because the tin plating is replaced and deposited. (FIG. 1 (g)).
[0024]
As described above, after the inner lead 4 and the outer lead 5 are formed on the surface of the insulating film 2 having flexibility, the masking resist is applied only to the inner lead 4, and only the outer lead 5 is subjected to electric solder plating. In the method of manufacturing a tin-solder two-color plating TAB tape in which tin plating is performed on the inner lead 4 by an electroless method after the resist is stripped, the solder plating composition applied to the outer lead 5 is Sn 60 to 70%, It has been confirmed that by applying electroless tin plating to the lead 4 and the outer lead 5, it is possible to prevent the occurrence of pitting of the outer lead solder plating and to obtain a solder plating film having a good composition in solderability. It was.
[0025]
【The invention's effect】
As explained above, according to the manufacturing method of the tin-solder two-color plating TAB tape of the present invention, the inner lead is subjected to electroless tin plating after setting the electric solder plating composition of the outer lead to Sn 60 to 70%. Further, it is possible to provide a tin-solder two-color plating TAB tape that can prevent the occurrence of pitting of solder plating applied to the outer lead and that has good solderability and bonding properties.
[Brief description of the drawings]
FIG. 1 is a view showing a method for producing a tin-solder two-color plating TAB tape of the present invention.
FIG. 2 is a diagram showing the relationship between the occurrence of solder plating pitting after electroless tin plating is applied when the solder plating composition is changed.
FIG. 3 is a plan view showing a tin-solder two-color plating TAB tape obtained by the production method of the present invention.
[Explanation of symbols]
1 Tin-solder 2 color plating TAB tape 2 Insulating film 3 Lead 4 Inner lead 5 Outer lead 6 Device hole 7 Sprocket hole 8 Outer hole 9 Test pad

Claims (3)

After forming the copper lead wiring pattern on the flexible insulating film, mask only the inner lead, apply the electric solder plating to the outer lead, peel off the masking agent, and then electroless tin plating the inner lead In the manufacturing method of the tin-solder two-color plating TAB tape to which the outer lead is applied, the inner lead is subjected to electroless tin plating after the electric solder plating composition of the outer lead is set to Sn 60 to 70%. Manufacturing method of color plating TAB tape. 2. The method for producing a tin-solder two-color plating TAB tape according to claim 1, wherein electroless tin plating is applied to the inner lead in an amount of 0.5 to 0.6 [mu] m. After forming the copper lead wiring pattern on the flexible insulating film, mask only the inner lead, apply the electric solder plating to the outer lead, peel off the masking agent, and then electroless tin plating the inner lead In the manufacturing method of the tin-solder two-color plating TAB tape to which the outer lead is applied, the inner lead is subjected to electroless tin plating of 0.5 to 0.6 μm after the electric solder plating composition of the outer lead is set to Sn 60 to 70%, A method for producing a tin-solder two-color plating TAB tape, wherein the solder plating composition of the outer lead after electroless tin plating is Sn 80 to 90% by substitution deposition of tin plating .

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