JPWO2006068000A1 - COF substrate laminate, method for producing the same, and COF film carrier tape formed using this COF substrate laminate - Google Patents

Abstract

It is possible to recognize the wiring of the driver IC chip through the insulating layer, and has a high adhesive force between the conductor and the insulating layer, and is excellent in electromigration resistance. For example, it can be finely processed with a pitch of 30 μm or less. A laminate and a method for manufacturing the same are provided. COF substrate laminate in which an insulating layer made of an insulating resin is formed on one side of a conductor made of conductive metal foil, the thickness of the conductor being 1-8 μm, and the surface in contact with the insulating layer of the conductor COF substrate laminate having a surface roughness Rz of 1.0 μm or less and a surface roughness Rz of the surface not contacting the conductor insulating layer of 1.0 μm or less, and a thickness of at least 10 μm or more An insulating layer is formed on the surface of the conductive metal foil having a surface roughness Rz of 1.0 μm or less on one surface, and the surface of the conductive metal foil not in contact with the insulating layer is chemically polished. This is a method for manufacturing a laminate for a COF substrate in which the conductive metal foil has a thickness of 1 to 8 μm and a surface roughness Rz of 1.0 μm or less to form a conductor.

Description

  The present invention relates to a laminate for a flexible printed circuit board used for COF applications and a method for producing the same.

  A TAB method (tape automated bonding) in which a driver IC is mounted on a tape carrier is widely used in the electronic industry using a liquid crystal display element (LCD).

  Recently, COF (chip-on-film), in which a bare IC chip is directly mounted on a film carrier tape, has been developed as a mounting method for mounting at a higher density in a smaller space.

  Since the flexible printed circuit board (FPC) used in this COF does not have the device holes that have been used in the TAB method, when measuring the relative position during chip mounting, the wiring of the driver IC chip is transmitted through the insulating layer. Need to recognize. In particular, in a flexible printed circuit board (FPC) used for this COF, it is necessary that the pitch of wiring advances and fine processing is possible.

  As a laminated body used for such an FPC for COF, there is a laminated body obtained by sputtering an adhesion reinforcing layer such as nickel on an insulating film such as a polyimide film and then performing copper plating. In such a copper-plated laminate, since the polyimide film is relatively transparent, the alignment during IC mounting is easy, but the adhesive force between the conductor and the insulating layer is weak, and the electromigration resistance There is a problem of inferiority.

  As a laminate that solves the above-mentioned problems, a cast-type laminate in which a polyimide film is laminated on a copper foil by a coating method, or an insulating film is thermocompression bonded to the copper foil via a thermoplastic resin or a thermosetting resin. There is a thermocompression bonding type.

  However, for casting-type laminates and thermocompression-type laminates, the problem of adhesion between the conductor and the insulating layer is solved to some extent. For example, in the region where the copper foil is removed by etching, the roughness of the copper foil There is a problem that the (surface roughness) is transferred to the insulating layer side, and the surface of the insulating layer irregularly reflects light and passes through the insulating layer so that the copper pattern cannot be recognized.

Therefore, Japanese Patent Application Laid-Open No. 2003-23046 discloses a laminate having a structure in which a conductor layer and an insulating layer are laminated, and the surface roughness of the surface of the conductor layer in contact with the insulating layer is 0.1 to 1.8 μm. Has been. However, although the above-mentioned laminated body can solve the problem of recognizing the wiring of the driver IC chip through the insulating layer to some extent, it is not always satisfactory as a high-density substrate material that requires a pitch of 30 μm or less, for example. It is not a thing. On the other hand, Japanese Unexamined Patent Application Publication No. 2004-142183 describes a laminate in which the surface roughness of the surface in contact with the insulating layer is 1.0 μm or less and the surface roughness of the back surface is 2.0 μm or less. However, when the surface roughness of the surface not in contact with the insulating layer is large, thickness unevenness occurs during resist formation, and it is difficult to improve the linearity of the circuit in the subsequent patterning process of the wiring circuit. Also, when the conductor is thick, it is difficult to ensure the linearity of the circuit, and in particular, it is difficult to perform fine processing with a pitch of 30 μm or less. That is, there was no laminated body in which the roughness on the insulating layer side and the roughness on the resist surface side were appropriate and could satisfy the requirements for fine processing.
JP 2003-23046 A JP 2004-142183 A

  Therefore, in the present invention, it is possible to recognize the wiring of the driver IC chip through the insulating layer, and the adhesive strength between the conductor and the insulating layer is high, and the electromigration resistance is excellent, for example, a pitch of 30 μm. An object of the present invention is to provide the following microfabricated laminate and a method for producing the same.

  In order to solve the above problems, the present inventors have intensively studied. As a result, the conductor forming the laminated body has a predetermined thickness, and the surface roughness Rz of the surface in direct contact with the insulating layer of the conductor is set. The inventors have found that the above problem can be solved by setting the surface roughness Rz of the surface not in contact with the insulating layer to 1.0 μm or less and 1.0 μm or less, thereby completing the present invention. The surface roughness Rz represents “10-point average roughness” and is measured according to JIS B 0601.

Therefore, the present invention is a COF substrate laminate in which an insulating layer made of an insulating resin is formed on one surface of a conductor made of a conductive metal foil, the thickness of the conductor being 1 to 8 μm, This is a COF substrate laminate in which the surface roughness Rz of the surface in contact with the insulating layer is 1.0 μm or less and the surface roughness Rz of the surface not in contact with the insulating layer of the conductor is 1.0 μm or less.
Further, the present invention is a method for manufacturing a laminate for a COF substrate in which an insulating layer made of an insulating resin is formed on one surface of a conductor, and has a thickness of at least 10 μm or more. An insulating layer is formed on the surface of the conductive metal foil having a surface roughness Rz of 1.0 μm or less, and the surface of the conductive metal foil not in contact with the insulating layer is chemically polished to reduce the thickness of the conductive metal foil. This is a method for producing a laminated body for a COF substrate, wherein the conductor is formed with a surface roughness Rz of 1.0 μm or less while being 1-8 μm.

  In the present invention, by setting the surface roughness Rz of the conductor in direct contact with the insulating layer to 1.0 μm or less, even if the roughness of the conductor is transferred to the insulating layer side during lamination with the insulating layer, the insulating layer The wiring of the driver IC chip can be recognized through the transmission. Further, by setting the surface roughness Rz of the conductor not in direct contact with the insulating layer to 1.0 μm or less, processing with a pitch of 30 μm or less is possible when high-density wiring is required. The surface roughness Rz of the conductor that is in direct contact with the insulating layer has a lower limit of 0.3 μm for ensuring the adhesion with the insulating layer, and the surface roughness Rz of the conductor that is not in direct contact with the insulating layer is The lower limit of Rz is 0.1 μm in order to ensure adhesion with an insulating protective film to be laminated later.

  Examples of the conductor made of the conductive metal foil in the present invention include a copper foil made of copper or a copper alloy, a metal foil made of gold, silver or the like, and preferably a copper foil. Examples of the copper foil include a rolled copper foil and an electrolytic copper foil, but an electrolytic copper foil that can reduce as much as possible the possibility of mixing an oxide that is an insulator is more preferable.

  Moreover, in this invention, the thickness of a conductor shall be 1-8 micrometers. If the thickness of the conductor is smaller than 1 μm, it is difficult to control the thickness during the chemical polishing process and sufficient reliability cannot be obtained. On the other hand, if it is larger than 8 μm, it becomes very difficult to obtain the linearity of the conductor when processing a pitch of 30 μm, for example.

  According to the present invention, it is possible to recognize the wiring of the driver IC chip through the insulating layer, the adhesive strength between the conductor and the insulating layer is high, the electromigration resistance is excellent, for example, 30 μm pitch or less It is possible to obtain a laminate that can be finely processed.

  Hereinafter, the present invention will be described in detail. In addition, although the example which forms a laminated body using electrolytic copper foil below is demonstrated, the laminated body in this invention and the method for obtaining this are not limited to the following content.

  When an electrolytic copper foil is used as a conductor made of a conductive metal foil, the electrolytic copper foil having a surface roughness Rz of 1.0 μm or less on the surface on which an insulating layer will be provided later is used. This is because, as described above, when an insulating layer is formed on this surface and the conductor is removed, the wiring of the driver IC chip can be recognized through the insulating layer. In order to secure adhesion with the insulating layer, Rz is preferably 0.3 μm or more. Moreover, although the thickness of the conductor in the finally obtained laminate is 1 to 8 μm, the thickness of this electrolytic copper foil is subjected to chemical polishing described later, so that the prepared copper foil has a thickness of 10 μm or more, Preferably, a material having a thickness of 12 to 18 μm is used.

  About the insulating layer which forms a laminated body, it may be formed, for example from the insulating film which has a thermoplastic resin layer, and may be formed from the insulating film which has a thermosetting resin layer. Alternatively, the polyimide precursor resin solution may be applied to the conductor, and the polyimide precursor resin solution may be dried and cured. Of these, the insulating layer is preferably formed by drying and curing after the polyimide precursor resin solution is applied to the conductor.

  About the said insulating layer, when apply | coating a polyimide precursor resin solution and forming by drying and hardening, it can manufacture by polymerizing a well-known diamine and an acid anhydride in presence of a solvent.

  Examples of the diamine used include 4,4′-diaminodiphenyl ether, 2′-methoxy 4,4′-diaminobenzanilide, 1,4-bis (4-aminophenoxy) benzene, and 1,3-bis (4- Aminophenoxy) benzene, 2,2′-bis [4- (4-aminophenoxy) phenyl] propane, 2,2′-dimethyl-4,4′-diaminobiphenyl, 3,3′-dihydroxy-4,4 ′ -Diaminobiphenyl, 4,4'-diaminobenzanilide and the like. Examples of the acid anhydride include pyromellitic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride. And 4,4′-oxydiphthalic anhydride. Each of the diamine and acid anhydride may be used alone or in combination of two or more.

  Examples of the solvent include dimethylacetamide, n-methylpyrrolidinone, 2-butanone, diglyme, xylene and the like, and they can be used alone or in combination of two or more.

  About the said polyimide precursor resin solution, it is preferable to apply | coat directly to one side of a conductor in a precursor state, and it is preferable to make the polymerized resin viscosity into the range of 500 cps-35,000 cps. The applied resin solution needs to be heat treated. For this heat treatment, for example, heat treatment is performed at 100 ° C. to 150 ° C. in the air for 2 minutes to 4 minutes, and then the temperature is raised from room temperature to 340 ° C. by vacuum heating. The process of returning to room temperature again should be performed for about 9 hours. The insulating layer made of the polyimide resin thus formed may be formed from only a single layer of the polyimide resin layer or may be formed from a plurality of layers. When the polyimide resin layer is formed from a plurality of layers, other polyimide resins made of different components may be sequentially applied on the polyimide resin layer. When the polyimide resin layer is composed of three or more layers, a polyimide resin composed of the same component may be used twice or more.

  For the laminate of the insulating layer and the conductor obtained above, the surface of the conductor not directly in contact with the insulating layer is chemically polished to reduce the thickness of the conductor to 1 to 8 μm and the surface roughness of this surface. Rz is set to 1.0 μm or less. The surface roughness of the copper foil varies depending on the conditions of chemical polishing. In the present invention, the copper foil surface roughness of a desired laminate is adjusted by adjusting polishing conditions such as a known polishing temperature and polishing rate. Can be adjusted. However, since the type and composition of the polishing liquid are important factors in relation to the surface roughness of the copper foil, the polishing liquid is preferably a hydrogen peroxide / sulfuric acid system containing hydrogen peroxide and sulfuric acid as main components. When using a hydrogen peroxide / sulfuric acid based polishing liquid, the concentration of hydrogen peroxide is preferably in the range of 70 to 85 g / L, and the concentration of sulfuric acid is preferably in the range of 18 to 22 g / L. If the concentration range is not within the above range, precise control of the surface roughness tends to be difficult. The polishing temperature is preferably kept constant at an arbitrary temperature of 20 to 50 ° C.

  In the above description, the insulating layer is formed by applying a polyimide resin on the electrolytic copper foil. However, for example, an insulating layer is formed by laminating one or more polyimide films on the electrolytic copper foil, and then, Chemical polishing as described in (1) may be performed.

  The laminate thus produced may be a single-sided copper-clad laminate having an electrolytic copper foil only on one side of the insulating layer, or a double-sided copper-clad laminate having an electrolytic copper foil on both sides of the insulating layer. . For double-sided copper-clad laminates, after forming a single-sided copper-clad laminate, a method of crimping electrolytic copper foil by hot pressing, a method of sandwiching a polyimide film between two electrolytic copper foils and crimping by hot pressing, etc. Can be mentioned. In any method, after crimping, the surface roughness Rz of the surface of the electrolytic copper foil that is not in direct contact with the insulating layer is made 1.0 μm or less and the thickness of the electrolytic copper foil is in the range of 1 to 8 μm. Do chemical polishing. Note that the surface roughness Rz of the electrolytic copper foil that is not in direct contact with the insulating layer is desirably 0.1 μm or more from the viewpoint of ensuring adhesion with an insulating protective film to be laminated later.

  Hereinafter, the present invention will be described in more detail with reference to examples.

In creating the laminate, the following four types of copper foils were prepared.
1) Copper foil 1: Electrolytic copper foil Insulation layer side Rz0.7μm, resist side Rz2.0μm
Mitsui Metal Mining Co., Ltd. NA-VLP foil thickness 15μm
2) Copper foil 2: Electrolytic copper foil Insulation layer side Rz 1.6μm, resist surface side Rz 1.5μm
F2-WS foil manufactured by Furukawa Circuit Foil Co., Ltd., thickness 12μm
3) Copper foil 3: Electrolytic copper foil Insulation layer side Rz2.5μm, resist surface side Rz1.5μm
Mitsui Kinzoku Mining Co., Ltd. SQ-VLP foil thickness 12μm
4) Copper foil 4: Electrolytic copper foil Insulation layer side Rz0.8μm, resist surface side Rz1.0μm
US Electrolytic Co., Ltd. USLPS foil thickness 18μm

[Synthesis Example 1]
N-methylpyrrolidinone was put in a reaction vessel equipped with a thermocouple and a stirrer and capable of introducing nitrogen. After soaking the reaction vessel in ice water contained in the vessel, pyromellitic anhydride (PMDA) was added to the reaction vessel, and then 4,4'-diaminodiphenyl ether, (DAPE) and 2'-methoxy-4,4 '-Diaminobenzanilide (MABA) was charged. The total amount of monomers charged was 15 wt%, the molar ratio of each diamine (MABA: DAPE) was 60:40, and the molar ratio of acid anhydride to diamine was 0.98: 1.0. Thereafter, stirring was further continued, and the reaction vessel was removed from the ice water when the temperature in the reaction vessel was in the range of room temperature to ± 5 ° C. Stirring was continued for 3 hours at room temperature, and the solution viscosity of the resulting polyamic acid was 15,000 cps.

[Synthesis Example 2]
N-methylpyrrolidinone was put in a reaction vessel equipped with a thermocouple and a stirrer and capable of introducing nitrogen. After immersing this reaction vessel in ice water contained in the vessel, PMDA / 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BTDA) was charged into the reaction vessel, and then 4,4'- Diaminodiphenyl ether (DAPE) was added. The total monomer charge was 15 wt%, and the molar ratio of acid anhydride to diamine was 1.03: 1.0. Thereafter, stirring was further continued, and the reaction vessel was removed from the ice water when the temperature in the reaction vessel was in the range of room temperature to ± 5 ° C. Stirring was continued for 3 hours at room temperature, and the solution viscosity of the resulting polyamic acid was 3,200 cps.

[Synthesis Example 3]
N-methylpyrrolidinone was put in a reaction vessel equipped with a thermocouple and a stirrer and capable of introducing nitrogen. After immersing this reaction vessel in ice water contained in the vessel, 3,3′4,4′-diphenylsulfonetetracarboxylic dianhydride (DSDA) and PMDA were charged into the reaction vessel, and then 1,3-bis (4-Aminophenoxy) benzene (TPE-R) was added. The total monomer charge was 15 wt%, the molar ratio of each acid anhydride (DSDA: PMDA) was 90:10, and the molar ratio of acid anhydride to diamine was 1.03: 1.0. Thereafter, stirring was further continued, and the reaction vessel was removed from the ice water when the temperature in the reaction vessel was in the range of room temperature to ± 5 ° C. Stirring was continued for 3 hours at room temperature, and the solution viscosity of the resulting polyamic acid was 3,200 cps.

    The polyamic acid solutions of Synthesis Examples 1 to 3 were sequentially applied to the surface of the copper foil 1 on the insulating layer side, and drying was repeated to obtain a laminate in which a polyimide precursor resin layer was formed on the copper foil. This laminated body was heat-treated at 340 ° C. for 8 hours to obtain a single-sided copper foil laminated body having a polyimide resin layer thickness of 40 μm (2 μm / 36 μm / 2 μm). This laminate is chemically polished with a polishing solution having a sulfuric acid concentration of 20 g / L, a hydrogen peroxide concentration of 80 g / L, and an additive concentration of 3% so that the copper foil has a thickness of 8.0 μm and is in contact with the polyimide resin layer. A conductor was formed such that the surface roughness Rz of the copper foil not formed was 0.8 μm, and a COF substrate laminate comprising a conductor and an insulating layer was obtained.

  A wiring pattern was formed on the laminate for a COF substrate obtained above to obtain a COF film carrier tape. At this time, the circuit pattern of the inner lead part was created at a pitch of 30μm, tin-plated, and then the linearity of the circuit was visually confirmed with a laser microscope with a magnification of 50 times, and the line width was observed to be uneven. NG was determined as NG. Thereafter, an IC having gold bumps was mounted on the inner lead portion of the COF film carrier tape. The flip chip bonder “TFC-2100” manufactured by Shibaura Mechatronics Co., Ltd. is used for mounting, and the bonding head tool temperature is 100 ° C, the stage temperature is 420 ° C, and the bonding pressure is 20 gf per bump. I went. At the time of this mounting, visibility was evaluated by recognizing whether or not an alignment mark used for IC alignment can be recognized by recognizing an image of the IC through a COF film carrier tape. After mounting, HHBT tester “ETAC HIFLEX” manufactured by Enomoto Kasei Co., Ltd. (85 ° C., 85% RT, 150 V, 1000 hours) was used for reliability evaluation. The results are shown in Table 1.

  Using a commercially available polyimide resin film (manufactured by Toray DuPont Co., Ltd., trade name: Kapton 150EN), apply the polyamic acid solution of Synthesis Example 1 on one side to a thickness of 2.0 μm after drying with a roll coater. After drying at 150 ° C. for 2 minutes, the polyamic acid solution of Synthesis Example 2 was applied to the other surface with a roll coater so that the thickness after drying was 2.0 μm, and at 70 ° C. for 5 minutes, 110 ° C. After drying for 5 minutes at 140 ° C. for 2 minutes, 180 ° C. for 5 minutes and 265 ° C. for 2 minutes, the side coated with the polyamic acid solution of Synthesis Example 1 is a non-thermoplastic polyimide resin layer. Thus, a polyimide insulating film having a thermoplastic polyimide resin layer on the side coated with the polyamic acid solution of Synthesis Example 2 was obtained.

  Next, the surface of the insulating film obtained above on the side of the thermoplastic polyimide resin layer and the surface of the copper foil 4 on the side of the insulating layer are overlapped, and using a roll laminator covered with silicon rubber, 240 ° C., pressure 1 The copper foil 4 and the said insulating film were bonded together on condition of 0.5 Mpa. Thereafter, annealing was performed in a batch-type autoclave at a temperature of 340 ° C. for 4 hours in a nitrogen atmosphere to obtain a laminate. The obtained laminate was chemically polished in the same manner as in Example 1 so that the copper foil had a thickness of 8.0 μm and the surface roughness Rz of the copper foil not in contact with the insulating film was 0.6 μm. A laminate for a COF substrate composed of a conductor and an insulating layer was obtained. The COF substrate laminate was mounted in the same manner as in Example 1, and image recognition during mounting, linearity of the inner leads, and reliability after COF mounting were evaluated. The results are shown in Table 1.

[Comparative Example 1]
Using the copper foil 2, a laminate was formed in the same manner as in Example 1, and chemical polishing was performed. The thickness of the conductor of the obtained laminate for COF substrate is 8.0 μm, the surface roughness Rz of the surface in contact with the insulating layer is 1.6 μm, the surface on the side not in contact with the insulating layer (resist surface side) The roughness Rz was 1.2 μm. This COF substrate laminate was mounted in the same manner as in Example 1, and image recognition during mounting, linearity of the inner leads, and reliability after COF mounting were evaluated. The results are shown in Table 1.

[Comparative Example 2]
Using the copper foil 3, a laminate was formed in the same manner as in Example 1, and chemical polishing was performed. The thickness of the conductor of the obtained laminate for COF substrate is 8.0 μm, the surface roughness Rz of the surface in contact with the insulating layer is 2.5 μm, and the surface not in contact with the insulating layer (resist surface side) The roughness Rz was 0.9 μm. This COF substrate laminate was mounted in the same manner as in Example 1, and image recognition during mounting, linearity of the inner leads, and reliability after COF mounting were evaluated. The results are shown in Table 1.

[Comparative Example 3]
A laminated body was formed using the copper foil 4 in the same manner as in Example 1. This laminated body was not subjected to chemical polishing. The thickness of the conductor of the obtained laminate for COF substrate is 18 μm, the surface roughness Rz on the surface in contact with the insulating layer is 0.8 μm, and the surface roughness on the side not in contact with the insulating layer (resist surface side) The thickness Rz was 1.0 μm. The COF substrate laminate was mounted in the same manner as in Example 1, and image recognition during mounting, linearity of the inner leads, and reliability after COF mounting were evaluated. The results are shown in Table 1.

[Comparative Example 4]
Using the copper foil 1, a laminate was prepared in the same manner as in Example 1 until just before chemical polishing. Next, this laminate is subjected to chemical polishing using a polishing liquid having a sulfuric acid concentration of 80 g / L, a hydrogen peroxide concentration of 20 g / L, and an additive concentration of 3% so that the thickness of the copper foil becomes 8.0 μm, A conductor was formed so that the surface roughness Rz of the copper foil not in contact with the polyimide resin layer was 1.6 μm, and a COF substrate laminate comprising a conductor and an insulating layer was obtained. This COF substrate laminate was mounted in the same manner as in Example 1, and image recognition during mounting, linearity of the inner leads, and reliability after COF mounting were evaluated. The results are shown in Table 1.

Claims (6)

  A laminate for a COF substrate in which an insulating layer made of an insulating resin is formed on one surface of a conductor made of a conductive metal foil, wherein the conductor has a thickness of 1 to 8 μm and is in contact with the insulating layer of the conductor A laminate for a COF substrate, wherein the surface roughness Rz of the surface is 1.0 μm or less, and the surface roughness Rz of the surface not in contact with the insulating layer of the conductor is 1.0 μm or less.   2. The COF substrate laminate according to claim 1, wherein the insulating layer is formed by directly applying a polyimide precursor resin solution to a conductor, followed by drying and curing.   3. The COF substrate laminate according to claim 1, wherein the insulating layer is formed by thermocompression bonding an insulating film having a thermoplastic resin layer to a conductor.   Conductive metal foil having a thickness of at least 10 μm and having a surface roughness Rz on one surface of 1.0 μm or less and an insulating layer formed on the surface of the conductive metal foil, which is not in contact with the insulating layer 2. The COF substrate according to claim 1, wherein a conductor is formed by chemically polishing the surface of the conductive metal foil to a thickness of 1 to 8 μm and a surface roughness Rz of 1.0 μm or less. Laminated body.   A COF film carrier tape formed using the laminate according to any one of claims 1 to 4.   A method for producing a laminate for a COF substrate in which an insulating layer made of an insulating resin is formed on one surface of a conductor, having a thickness of at least 10 μm and a surface roughness Rz of one surface of 1.0. An insulating layer is formed on the surface of the conductive metal foil having a thickness of μm or less, and the surface of the conductive metal foil not in contact with the insulating layer is chemically polished so that the thickness of the conductive metal foil is 1 to 8 μm. A method for producing a laminate for a COF substrate, wherein the conductor is formed with a surface roughness Rz of 1.0 μm or less.