KR100448265B1 - A process of Tin Double Plating at TAPE AUTOMATED BONDING and CHIP on Film - Google Patents

Abstract

A tape carrier film and a method for producing a COF are provided.

In the present invention, the first copper plating on the film laminated copper foil with the electrical wiring pattern is heat-treated, followed by applying a solder resistor to the predetermined position of the heat-treated film and heat-cured, then secondary plating of tin In the tape carrier film and the COF manufacturing method by a double tin plating process, before the second tin plating, a portion of the thickness of the primary tin plating layer is removed in the region where the solder resistor is not applied. And to a method for producing COF.

Description

A process of Tin Double Plating at TAPE AUTOMATED BONDING and CHIP on Film}

The present invention relates to a method for manufacturing a tape carrier film (TAPE CARRIER FILM <Tape Automated Bonding>) and a COF (Chip on Film) for mounting electronic components such as IC, more specifically, the present invention is a tape carrier with double tin plating In the process of manufacturing a film or the like, after the primary tin plating, a part of the plating layer is removed, and then the secondary tin plating is performed, thereby performing a tape carrier film that can improve the melt defect during the inner lead bonding between the final product and the semiconductor chip. It relates to a manufacturing method.

As electronic products are miniaturized, the wiring of semiconductor ICs used therein is required to be finer. Accordingly, tape carrier films for mounting electronic components such as TAB, T-BGA, and ASIC are widely used.

The general process of manufacturing such a tape carrier film is as follows. That is, punching is first performed at a predetermined position of a known film made of polyimide or the like to which an adhesive is adhered, and then the copper foil is deposited on the film to which the adhesive is adhered. In order to improve the refractive index in the final product state, the polyimide ink is applied to the punched position on the back surface of the film on which the copper foil is laminated and thermally cured, and the copper foil is etched to form an electrical wiring pattern.

In this way, a solder-resist, which is a protective layer of the circuit, is applied to the tape carrier film for mounting the electronic component on which the wiring pattern is formed, except for connection parts such as solder ball terminals. A tin post-plating process for post tin plating is generally used.

1 is a process chart for manufacturing a tape carrier film by such a post plating process. As shown in FIG. 1, after the copper foil 13 is deposited on the polyimide film 11 using the adhesive 15, an electrical wiring pattern is formed. Then, a tape carrier film was produced by applying a solder resist 17 to a predetermined position of the film on which the wiring pattern was formed, followed by thermal curing treatment, and then tin plating 19 in an area where the solder resist was not coated.

The method of manufacturing a tape carrier film by such a post-plating process is advantageous at the point of shortening the manufacturing process. However, the tin plating solution penetrates into the solder resist interface and the solder resist is lifted, so that the area to be plated may be "copper exposure" phenomenon. Therefore, the "copper exposure" occurs in the copper corrosion area. There is a problem in that a circuit in which the electrical wiring is made weak becomes broken, and a short circuit occurs between adjacent circuits due to copper migration.

Furthermore, after the primary tin plating, heat treatment should be performed in the oven. However, in order to achieve the pure plating thickness according to the specified specification, the thermal curing time and control should be performed after the application of the solder resistor afterwards. Due to stagnation, the stress caused by the isomer is generated in the plated tin layer and the alloy layer with copper, resulting in a "spiky" in the shape of a peak. Such "whiskers" continue to grow and are mounted in ICs. Later, a short circuit with the adjacent circuit occurred.

Therefore, the present inventors have proposed a method for manufacturing a tape carrier film, etc. through double tin plating in order to solve the above problems as the Republic of Korea Patent Application No. 2001-51986. As shown in FIG. 2, in the method, first, the copper foil 22 is deposited on the polyimide film 21 using the adhesive 23, and then an electrical wiring pattern is formed. Subsequently, after performing the primary tin plating 25 on the film on which the wiring pattern is formed, the solder resist 27 is applied to the predetermined position and thermally cured. Finally, the secondary tin is applied to the area where the solder resist is not coated. Plating 29 was performed to produce a tape carrier film.

This double tin plating method is effective in solving the problems such as "copper exposure" or "whisker generation" of the above-described post-plating process. However, there was a problem in that a melting defect occurred when bonding with a semiconductor IC chip on the demand side in the future using the final product manufactured by the double tin plating method.

Therefore, the present invention is to solve the problems of the prior art described above, when manufacturing the tape carrier film by the double tin plating method, after the first tin plating, after removing a part of the plating layer and performing the second plating, copper foil exposure or It is an object of the present invention to provide a tape carrier film and a method for producing a COF that can prevent whiskers as well as solve a problem of melting defects.

1 is a schematic cross-sectional view of a tape carrier film for mounting an electronic component manufactured by a conventional post plating process.

Figure 2 is a schematic cross-sectional view of a tape carrier film for mounting electronic components manufactured by a conventional double tin plating process

3 is a manufacturing process diagram of the tape carrier film for mounting electronic components according to the present invention.

4 is a schematic cross-sectional view of an electronic component mounting COF manufactured according to the method of the present invention.

* Description of the symbols for the main parts of the drawings *

31 ...... Insulation film 32 ...... Copper foil

33 ...... Adhesive 34 ...... 1st Tin Plating Layer

35 ...... Solder resistor 36 ...... 1st plating layer removal part

37 ...... Secondary Tin Plating Layer

Hereinafter, the present invention will be described.

As described above, the manufacture of the tape carrier film by the double tin plating method is effective in solving the copper foil exposure and the whisker occurrence problem caused by the conventional post plating process, but the product manufactured by the double tin plating method is expected to be in the future. In the subsequent process of bonding with the IC chip, there is a problem that causes a melting failure.

Accordingly, the present inventors have repeatedly conducted research and experiments to solve the above problems, and the present invention proposes the present invention on the basis of the results. It is characterized by removing part of the thickness of the primary tin plating layer before the primary tin plating.

In general, the inner lead of the tape carrier film (TAB) made of double tin plating and the bump of the IC chip are bonded by applying heat and pressure. Such bonding is plated by heat and pressure without using a separate adhesive. This is done by melting the annotation. Therefore, if the thickness of the formed pure tin plated layer is less than a certain thickness, even though bonding is performed, pull strength may be lowered, thereby causing a poor melting.

In the conventional double tin plating process, since the primary tin plating layer constitutes a copper-tin alloy layer through subsequent heat treatment and heat curing treatment process, the tin plating layer participating in the actual bonding is the tin plating layer existing on the secondary tin plating layer. It can be said. Therefore, it is necessary to increase the thickness of the secondary tin plating layer as much as possible in order to solve the melting defect, but the overall plating layer thickness itself is also limited because the demand is limited by the specifications.

Therefore, in the present invention, when manufacturing a tape carrier film by a double tin plating process, after removing a part of the primary tin plating layer constituting the copper-tin alloy layer as a whole, the second tin plating is performed to meet the specifications of the demand while By increasing the thickness of the secondary tin plating layer is characterized in that the removal of the melting defects.

Therefore, in the present invention, the first copper plating on the film laminated copper foil with the electrical wiring pattern is heat-treated, and then, the solder resistor is applied to the predetermined position of the heat-treated film, and the heat curing after the tin is secondary In the tape carrier film manufacturing method by a double tin plating process to plate,

It relates to a tape carrier film and a method for producing a COF, characterized in that before the secondary tin plating, a part of the thickness of the primary tin plating layer is removed in the region where the solder resistor is not applied.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is a manufacturing process diagram of the tape carrier film for mounting electronic components according to the present invention.

As shown in FIG. 3A, first, in the present invention, the copper foil 32 is laminated on the insulating film 31, and the laminated copper foil is etched to prepare a film having a wiring pattern. In this case, the insulating film may be formed of a resin film such as glass epoxy, polyester, polyimide, etc., More preferably, the insulating film is formed of a polyimide film.

Then, the copper foil 32 is bonded and laminated on the insulating film 31 using the adhesive 33, and then a photoresist is applied to the surface of the copper foil 32, and the film is applied to a predetermined position on the film. A wiring baton is formed through the process of developing after exposure.

If a wiring pattern is formed on the film in which copper foil was laminated | stacked, tin film is first electroless-plated 34 next to the film in which the wiring pattern was formed like FIG.3 (b). At this time, the electroless plating for 2 to 3 seconds at a temperature of 60 ~ 70 ℃ usually, from which a coating layer is generally formed to a thickness of approximately 0.08 ~ 0.12㎛.

After the tin plating, in order to relieve thermal stress of the tin plating layer, the first plated film is heat-treated in an oven maintained at 120 to 140 ° C., in which heat treatment is preferably performed for 20 to 90 minutes, more preferably. Is a nitrogen gas is injected during the heat treatment at a pressure of 0.07 to 0.15 Kg / cm 2. This heat treatment process serves to prevent whiskers by relaxing the thermal stress of the tin-plated layer, copper foil layer and the intermetallic compound layer combined with tin plating.

Next, as shown in FIG. 3 (c), the solder resistor 35 is applied to a predetermined position of the heat-treated film after the primary tin plating, and then thermally cured, and the same copper component constituting the terminal in the thermal curing process is primary. Diffused to the plated tin plating layer, the pure tin plating layer thickness of the primary plating layer is zero.

At this time, the heat curing treatment is preferably a two-stage heat curing after the heat curing for 20 to 40 minutes at a temperature of 50 ~ 60 ℃ in the oven, 50 to 60 minutes at a temperature of 120 ~ 140 ℃.

On the other hand, as described above, the present invention is characterized in that after the thermosetting process, a portion of the thickness of the primary tin plating layer 36 is removed before the subsequent secondary tin plating process in a region where the solder resistor is not applied. (FIG. 3 (d)).

That is, when tin plating is performed in a conventional method for 2 to 3 seconds on the film on which the wiring pattern is formed, the thickness of the plating layer reaches 0.12 μm, thereby restricting the thickness of the plating layer that can be plated in subsequent secondary plating. Malting problem cannot be avoided. Therefore, in the present invention, by removing a portion of the first plating layer before the second tin plating, the thickness of the second plating layer can be relatively increased, thereby preventing malting defects.

In the present invention, the removal of the primary tin-plated plating layer is not limited to the specific method of removing the plating layer. Preferably, the primary tin-plated plating layer is deposited on the nitric acid solution and the sodium triphosphate solution to remove the plating layer. More preferably, the thermally cured film is immersed in a nitric acid solution having a nitrate concentration of 40 to 80% and a sodium triphosphate solution having a concentration of 30 to 70 g / L of sodium triphosphate to remove the primary plating layer. And the temperature of the sodium triphosphate solution and nitric acid solution is preferably controlled to 25 ~ 55 ℃ and 25 ~ 45 ℃, respectively.

In addition, when removing some of the plating layer, it is preferable that the thickness of the plating layer to be removed in the range of 0.05 ~ 0.1㎛.

As shown in FIG. 3 (e), in the present invention, electroless plating 37 of tin is secondarily performed on the portion of the film from which the primary tin plating layer is removed. Such secondary tin plating is preferably carried out for 150 to 230 seconds at a temperature of 60 ~ 70 ℃. In addition, the thickness of the plating layer is preferably limited to 0.4 ~ 0.6㎛. The secondary plated film is heat-treated again in an oven, etc. At this time, the heat treatment temperature is preferably limited to 120 ~ 140 ℃, heat treatment time to 60 ~ 90 minutes.

When the secondary tin plated film is heat-treated as described above, the secondary tin plated layer is composed of a copper and tin alloy layer and a pure tin layer as the copper is diffused. However, in the present invention, as described above, since the second tin plating is performed after removing a part of the first tin plating layer, the thickness of the second tin plating layer is relatively higher than that of the conventional double tin plating method in which the first tin plating layer is not performed. Can be effectively increased.

Therefore, the present invention can effectively prevent copper foil exposure or whisker generation by adopting the double tin plating method in manufacturing the tape carrier film and the COF, and also by removing a part of the primary tin plating layer before the secondary tin plating. It is possible to prevent the problem of melt failure caused in the subsequent process of bonding the IC chip with.

On the other hand, Figure 4 is a schematic cross-sectional view of a manufactured COF for mounting an electronic component according to the present invention, it can be manufactured under the same conditions as the tape carrier film manufacturing process described above.

Hereinafter, an Example is given and this invention is demonstrated in detail.

(Example 1)

Copper foil was stuck to the polyimide film using an adhesive agent, the wiring pattern was formed in the bonded copper foil, and copper foil was etched. And 4,000 films in which this wiring pattern was formed were prepared, and the tape carrier film was produced by different manufacturing conditions by 1,000 pieces for each case as follows.

Case 1

In Example 1, after applying a solder resistor to the predetermined position of the copper foil in which the wiring pattern was formed, one-step thermosetting was carried out in an oven for 30 minutes at a temperature of 60 ° C, followed by two-step thermal curing at a temperature of 120 ° C for 60 minutes.

Then, tin plating was performed on the copper foil to which the solder resist was not applied at a temperature of 65 ° C. for 170 seconds to form a plating layer having a thickness of 0.4 to 0.6 μm, and then heat-treated in an oven at 70 ° C. for 70 minutes to form a tape carrier film. Prepared.

Case 2

In Example 2, the film on which the wiring pattern was formed was tinned at 170 ° C. for 170 seconds to form a plating layer having a thickness of 0.4 to 0.6 μm, and then heat-treated in an oven at 120 ° C. for 90 minutes.

The solder resist was applied to a predetermined position of the thermally cured film, and then a first carrier was cured at 60 ° C. for 30 minutes at a temperature of 60 ° C., followed by two-step heat curing at 120 ° C. for 60 minutes to prepare a tape carrier film. .

Case 3

In Example 3, the first tin plating was performed at a temperature of 650 ° C. for 2 to 3 seconds at a predetermined position on the copper foil on which the wiring pattern was formed to form a plating layer having a thickness of about 0.08 to 0.12 μm, and then at 140 ° C. in an oven. Heat treatment was performed for 20 minutes. Then, after applying the solder resist to the predetermined position, one-step heat curing treatment for 30 minutes at 60 ℃ temperature in the oven, and two-step heat curing treatment for 60 minutes at 120 ℃ temperature.

Next, the thermally cured film was subjected to secondary tin plating for 170 seconds at a temperature of 65 ° C. to form a plating layer having a thickness of 0.4 to 0.6 μm, and then heat-treated at 140 ° C. for 70 minutes in an oven. Tape carrier films were prepared.

Case 4

In Example 4, primary tin plating was carried out on the film on which the wiring pattern was formed at a temperature of 65 ° C. for 2 to 3 seconds to form a plating layer having a thickness of about 0.08 μm to 0.12 μm, and then 20 degrees at 140 ° C. in an oven. Heat treated for minutes. Then, after applying the solder resistor at a predetermined position, one-step heat curing treatment for 30 minutes at 60 ℃ temperature in the oven, and two-step heat curing treatment for 60 minutes at 120 ℃ temperature.

The thermally treated film was immersed in a nitric acid solution having a nitric acid concentration of 55% and maintaining 35 ° C, and a sodium triphosphate solution having a concentration of 40 g / L and a temperature of 45 ° C. Μm to 0.1 μm were removed, and then, secondary tin plating was performed at 65 ° C. for 170 seconds to form a plating layer having a thickness of about 0.4 μm to 0.6 μm. And the final product was prepared by heat treatment for 70 minutes at 140 ℃ temperature in an oven.

As described above, the degree of copper exposure and whisker occurrence of the final product manufactured under different manufacturing process conditions were measured, and the bonding defects caused by the bonding during bonding with the semiconductor IC chip are shown in Table 1 below.

Number of defects found Total number of samples Total defects Remarks Exposure Whiskers Melting defect Case 1 132 6 5 1000 143 Conventional example Case 2 20 91 14 1000 126 Case 3 17 9 168 1000 194 Comparative example Case 4 11 4 2 1000 17 Inventive Example 1

As shown in Table 1, it can be seen that the case of using a double tin plating method while removing part of the first tin plating layer before the second tin plating, there is almost no copper exposure, whiskers and poor melting.

On the other hand, in the case of the case 1 to 2 manufacturing the tape carrier film in the tin post-plating process and the leading gold process, the degree of melt defect is excellent, but the copper exposure and whiskers occur, it can be seen that it is difficult to manufacture a reliable product.

In addition, in case 3, which uses the double tin plating method but does not remove the first tin plating layer before the second tin plating, defects caused by copper exposure and whiskers can be solved, but many of the defects have occurred. It can be seen that the actual pure tin layer does not fall within a certain range.

(Example 2)

A tape carrier film was prepared under the same conditions as in Example 4 of Example 1. However, at this time, the removal conditions of the primary tin plated layer were different as shown in Table 1 below, and 1000 samples were prepared under the respective conditions to evaluate the melting failure, and the results are also shown in Table 2 below.

nitric acid Sodium triphosphate Number of samples Malting defect Temperature (℃) density(%) Temperature (℃) Concentration (g / L) Inventive Example 2 25 45 35 30 1000 5 3 25 55 45 40 1000 23 4 35 45 35 30 1000 4 5 35 55 45 40 1000 One

As shown in Table 2, by optimizing the concentration of nitric acid and sodium triphosphate, and by removing a portion of the primary tin plating layer using a nitric acid solution and sodium triphosphate solution in which the temperature range is properly controlled, the degree of melt failure is effectively reduced It can be seen that.

As described above, the present invention, when manufacturing the tape carrier film by the double tin plating method, it is possible to prevent copper foil exposure or whisker generation by performing secondary plating after removing a part of the plating layer after the primary tin plating. In addition, there is a useful effect in the manufacture of a tape carrier film and COF that can effectively prevent the melt failure.

Claims (3)

Double tin plating for primary plating of tin on a laminated film of copper foil having electrical wiring patterns, followed by heat treatment, followed by application of a solder resistor to a predetermined position of the heat-treated film, thermal curing, and second plating of tin. In the tape carrier film and COF manufacturing method by the step, Tape carrier film and COF manufacturing method characterized in that before the secondary tin plating, a part of the thickness of the primary tin plating layer is removed in the region where the solder resistor is not applied. The method of claim 1, wherein the thickness of the primary tin plated layer is removed in a range of 0.05 μm to 0.1 μm. The method of claim 1, wherein the thermally cured film is immersed in a nitric acid solution of 40-80% nitric acid and sodium triphosphate solution of 30-70 g / L concentration of sodium triphosphate to remove the primary plating layer. Tape carrier film and COF manufacturing method.