KR100330557B1 - Method of manufacturing flexible substrate circuit film - Google Patents

Abstract

According to the present invention, in order to solve the variation of the plating thickness according to the position of the plating layer of nickel, which is a diffusion barrier layer, and the occurrence of plating defects during the patterning of the solder resist, copper is coated on one side of the polyimide film. Substrate film is used. Nickel plating process and gold strike process in the order of photoresist, coating, exposure, development, etching, photoresist peeling, nickel plating, photo solder resist coating, weak heat curing, exposure, developing, intense curing, and gold plating. Is carried out prior to the photosolder coating process to reduce the nickel plating variation caused by the current density unevenness due to the pattern formation of the solder resist in the nickel plating process, and the residual of the solder resist remaining in the metal conductive layer after the solder resist pattern is formed. Completely eliminates plating defects caused by plating process due to poor adhesion between materials and solder resist. In addition, the present invention also provides a method for manufacturing a flexible substrate circuit film in which height uniformity and adhesion of a solder ball hold are increased.

Description

Method of manufacturing flexible substrate circuit film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a flexible substrate circuit film, wherein the flexible substrate circuit film is an interposer in manufacturing a wafer size CSP using wafer level packaging technology. (Substrate Circuit Film) is the main core material of CSP and consists of copper thin film conductive circuit on polyimide substrate, and is a light and thin element that electrically connects electrical and electronic devices such as semiconductor chip and printed circuit board as an alternative material of lead frame. It is a new medium of directivity.

In general, a circuit film of a substrate uses a polyimide film as a support and a film coated with copper on one or both sides as a substrate. The manufacturing process includes photoresist coating, exposure, development, etching, photoresist peeling and nickel / gold. The substrate circuit film of the wafer size CSP is made by plating and then plating nickel / gold after forming a pattern in a specific shape as required.

In the case of manufacturing a circuit film of a wafer size substrate by such a process, plating defects occur due to the adhesion between the material remaining in the metal conductive layer and the solder resist due to the variation of the plating thickness according to the position of nickel plating and the defect of the solder resist. There was a problem caused.

The present invention is to solve the above problems, the object of the present invention is to provide a process for manufacturing a flexible substrate circuit film (Substrate Circuit Film) which is the main constituent material of the chip size package (CSP) at the wafer level thickness variation of the plating By minimizing to maintain the uniform height of the solder ball hole and to increase the adhesion of the solder resist.

Therefore, the above object is achieved by performing the nickel plating process and the gold strike process in advance of the photosolder resist coating process, and the photoresist, coating, exposure, developing, etching, photoresist peeling, nickel plating, photosolder resist coating, It is achieved by providing a method for producing a flexible substrate circuit film provided in the order of weak heat curing, exposure, development, intense heat curing, and gold plating.

1 is a manufacturing process diagram of a wafer scale CS substrate circuit film of a first embodiment of the present invention;

2 is a manufacturing process chart of a wafer scale CSP substrate circuit film of a second embodiment of the present invention;

3 is a manufacturing process chart of a wafer scale CS substrate circuit film of a third embodiment of the present invention;

Figure 4 is a cross-sectional view showing a layer structure according to the manufacturing process of the wafer scale CS substrate circuit film of the third embodiment of the present invention,

5 is a circuit diagram of a wafer-scale CS substrate to be attached to an actual wafer according to the present invention;

6 is an enlarged circuit diagram of the portion A;

7 is a cross-sectional view illustrating a state in which chips are bonded using the substrate circuit film.

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

Referring to FIG. 4, as the flexible substrate film, copper (3) was applied to one side of the polyimide film (1) by using an adhesive (2), but the purpose of manufacturing a circuit pattern on the surface of copper was applied. It can be used in the following three examples.

(Example 1)

Nickel plating and gold strike plating are performed prior to the application of photosolder resist, and plating is performed before the lead frame pattern is formed on the copper 3 prior to the application of the solder resist and the pattern formation of the ball pad and the wire bonding pad. Degreasing, pickling, photoresist coating, exposure, development, etching, photoresist stripping, degreasing, pickling, nickel plating, gold strike, photosolder coating, weak heat curing, exposure, development, degreasing, pickling , Gold plating, heat curing method in order.

When the embodiment is described in detail as shown in FIG. 1, after performing a process of removing the surface contaminants and the copper oxide film of the substrate film in an alkali degreasing process and an acid washing process, a photoresist dry film (C) is formed on the copper surface to form a pattern. 4) applying (10) to the conditions of 105 to 115 DEG C and 1 to 1.5 meters / min, exposing to 20 (exposure) of 25 to 50 mj, and developing the exposed dry film (4). A step (30), an etching step (40) using an etching solution of chloride transfer, a step (50) of peeling off the photoresist dry film (4) with a sodium hydroxide solution, and a copper conductive circuit pattern formed at this step Plating (5) the nickel (5) so as to have a thickness of 5 to 15 [mu] m under the conditions of a current density of 50 ASF on the upper part, and a thickness of 0.075 to Gold plated gold strike (7) to 0.125㎛ Insulating photosolder resist 6 using a printer uniformly so as to have a thickness of at least 10 μm, preferably 20 μm, on the upper surface of the substrate including the system 70 and the gold strike 7 plating layer in this step. ) Step (80), 75 ~ 85 ℃, the step of weak heat curing at the conditions of 25-40 minutes (90), and the pattern exposure to form a solder ball hole and bonding pads at an exposure amount of 500 ~ 700mj 100, developing 110 the exposed portion, exposing the wire bonding pad portion for connecting the semiconductor chip and the solder ball hole portion for connecting the printed circuit board 120, and formed in this step After the airtight film surface was treated by alkali degreasing process and acid washing process, plating (8) of gold (8) so as to have a thickness of 0.5 to 1.0 μm at 3.5 ASF, and 140 to 160 ° C. for 25 to 40 minutes after this step. Intensive curing of the photosolder resist (140) By performing the substrate circuit film as shown in Figures 5 and 6. Here, the alkali degreasing step and the acid washing step are omitted in the general description.

As a result, the nickel plating 60 was applied prior to the application of the solder resist and the pattern formation of the ball pads and the wire bonding pads 100 to reduce the nickel plating deviation caused by the solder resist pattern in the nickel plating process and to be generated after the pattern formation. Although the plating defect can be removed, there is a problem in that the gold plating solution penetrates into the lower portion of the photosolder which is in close contact with the gold plating process when the gold plating process is performed only by weak heat curing.

(Example 2)

Nickel plating and gold strike plating are performed prior to photosolder application, and furthermore, the problem occurring in Example 1 is solved by carrying out the hardening fixation prior to the gold plating.

Namely, degreasing, pickling, photoresist coating, exposure, development, etching, photoresist stripping, degreasing, pickling, nickel plating, gold strike, photosolder resist coating, weak heat curing, exposure, development, heat curing, degreasing, arithmetic Three, the manufacturing method by the order of gold plating.

The second embodiment will be described in detail step by step as shown in Figure 2, after removing the surface contaminants and copper oxide film of the substrate film in the alkali degreasing process and pickling process photoresist dry film on the copper (3) surface for pattern formation (10) applying (4) to the conditions of 105 ° C to 115 ° C and 1 to 1.5 meters / min, exposing the photoresist dry film 4 to 20 ° C for an exposure dose of 25 to 25mj, and A step 30 of developing the exposed portion in this step, a step 40 of etching the copper (2) using an etching solution of chlorine chloride, and peeling off the photoresist dry film (4) with sodium hydroxide solution And degreasing and pickling the upper portion of the copper conductive circuit pattern formed by the step (50) to remove surface contaminants and copper oxide films, and then the nickel (5) to have a thickness of 5 to 15 µm under the condition of a current density of 50 ASF. Plating (60) and this step In step (70) of plating a gold strike (7) having a thickness of 0.075 ~ 0.125㎛ on the upper surface of the nickel (5) plated film at a current density of 3.5ASF, and the gold strike (7) plating layer of this step Applying the insulating photosolder resist (6) 80 using a printer uniformly to a thickness of at least 10 μm, preferably 20 μm, on the upper surface of the substrate comprising the substrate film of this step, A step (90) of weak heat curing at a condition of 75 to 85 ° C. and 25 to 40 minutes, and a step (100) of pattern exposure forming a solder ball hole and a bonding pad at an exposure dose of 500 to 700 mj, Developing a portion 110, exposing a wire bonding pad portion for connecting a semiconductor chip and a solder ball hole portion for connecting a printed circuit board 120, and strengthening the network structure of the photosolder resist 6. 140 to 160 to increase adhesion Intensive hardening of the photosolder resist at 140 ° C. for 25 to 40 minutes (140), and the surface of the substrate film in this step was treated with an alkali degreasing process and an acid washing process so that the thickness was 0.5 to 1.0 μm at 3.5ASF. Performing the step (130) of plating (8) to prepare a substrate circuit film as shown in FIGS. Here, the water washing for each step is omitted.

The result of the thermal aging 140 was performed before the gold plating 30, so that there was no penetration of the gold solution between the photosolder resist and the gold strike layer during the gold plating process, and the thermal aging test of the prepared substrate circuit (Thermal Aging) Photosolder and plating surface in the reliability test of the test, the specimen was heat treated at 175 ℃ for 7 hours and 30 minutes) and the steam aging test (Steam Aging Test, the specimen was subjected to forced aging for 8 hours under 95 ° C 95% relative humidity). There was no departure from.

(Example 3)

Nickel plating is performed prior to photosolder application and the intensive curing process is performed prior to the gold strike plating and gold plating processes.

Namely, degreasing, pickling, photoresist coating, exposure, development, etching, photoresist stripping, degreasing, pickling, nickel plating, photosolder coating, weak heat curing, exposure, development, strong curing, degreasing, pickling, gold Manufacturing method by the order of strike and gold plating.

3 and 4, the photoresist dry film 4 is removed to form a pattern after removing the surface contaminants and the copper oxide film of the substrate film in the alkali degreasing process and the acid washing process. (10) coating on the film of this step under the conditions of the exposure amount of 25-50mj (20), and developing the exposed part after this step Performing a step 30, etching the copper 3 using an etching solution of chlorine chloride after the step 40, and peeling the photoresist dry film 4 using a sodium hydroxide solution after this step. And removing the contaminants and the copper oxide film on the upper portion of the copper conductive circuit pattern formed by the step by an alkali degreasing process and an acid washing process, and then adding nickel (5) to a thickness of 5 to 15 μm under conditions of a current density of 50 ASF. Plating) (60) Applying an insulating photosolder 6 to the upper surface of the substrate including the nickel plated layer formed by this step using a printer uniformly so as to have a thickness of at least 10 μm, preferably 20 μm (80) And a step (90) of weak heat curing at a condition of 75 to 85 ° C. and 25 to 40 minutes after this step, and then exposing the upper part of the pattern forming the solder ball hole and the bonding pad at an exposure dose of 600 mj (after this step) 100), a step 110 of performing development after this step, a step 120 of exposing a wire bonding pad portion for connecting a semiconductor chip and a solder ball hole portion for connecting a printed circuit board, and a photo after this step. In order to increase the network reinforcement and adhesion of the solder resist 6, the step of thermal hardening at 140 to 160 ° C. and 25 to 40 minutes is carried out at 140 ° C, and finally after the alkali degreasing process and the acid washing process are performed. Density 3.5ASF Plating a gold strike (7) having a thickness of 0.075 to 0.125 mu m under the conditions (70), and plating gold (8) so as to have a thickness of 0.5 to 1.0 mu m at 3.5ASF on the gold strike layer formed in this step. Performing 130, to prepare a substrate circuit film, as shown in FIGS. Here, the water washing for each step is omitted.

The results of the experiment were conducted by the gold strike plating 70 after the intensive heat curing 140. There was no penetration of the gold solution between the photosolder resist and the gold strike layer during the gold plating process, and the thermal aging test of the prepared substrate circuit (Thermal Aging) Plating surface of the photosolder resist in the reliability test of the test, heat treatment at 175 ° C for 7 hours 30 minutes) and steam aging test (Steam Aging Test, 8-hour forced aging at 95 ° C 95% relative humidity) There was no departure from.

As described above, the present invention, by the nickel plating for preventing the diffusion of copper ions of the bottom layer in the manufacturing process of the substrate circuit film of the wafer level CSP prior to the application of the solder resist and the pattern formation of the ball pad and wire bonding pad In the nickel plating process to reduce the nickel plating variation caused by the current density unevenness due to the pattern formation of the solder resist, and the plating according to the poor adhesion between the residual material of the solder resist and the solder resist remaining in the metal conductive layer after the solder resist pattern is formed. The plating defects caused by the process could be completely eliminated, and the uniformity and adhesion of the height of the solder ball hole may be increased.

Claims (6)

In the process of manufacturing a substrate circuit film of a wafer size chip size package, forming a copper conductive pattern on the copper layer side of the polyimide substrate film using photolithography technique, and forming a nickel plating layer on the copper conductive circuit pattern. Forming a gold strike plating layer on the nickel plating layer, and applying a photo solder resist on a polyimide substrate having a conductive pattern of the gold strike plating layer to form a solder resist pattern forming a solder ball hole and a bonding pad using a photolithography technique. And hardening the patterned solder resist, and forming a gold plated layer on the gold strike layer exposed by the solder resist pattern. In the process of manufacturing a substrate circuit film of a wafer size chip size package, forming a copper conductive pattern using a photolithography technique on the copper layer side of the polyimide substrate film, and forming a nickel plating layer on the copper conductive circuit pattern. And applying a photo solder resist on the polyimide substrate having the conductive pattern of the nickel plated layer to form a solder resist pattern forming a solder ball hole and a bonding pad using a photolithography technique, and heating the patterned solder resist. And hardening, gold strike plating is performed on the nickel plating layer exposed by the solder resist pattern, and a gold plating layer is formed on the gold strike plating layer. A method according to claim 1 or 2, characterized by using photolithography techniques comprising photoresist application, development, metal etching and photoresist stripping. Claim 4 has been deleted. Claim 5 has been deleted. A method according to claim 1 or 2, characterized in that the work is carried out in an alkali degreasing solution or an acidic solution before each step.