JP4642479B2 - COF laminate and COF film carrier tape - Google Patents

Description

  The present invention relates to a COF (Chip on Film) laminate on which an electronic component such as an IC or LSI is mounted, and a COF film carrier tape obtained by processing the laminate.

  With the spread and development of electronic devices such as cameras, personal computers, mobile phones, and liquid crystal displays, the demand for printed wiring boards that mount electronic components such as ICs (integrated circuits) or LSIs (large-scale integrated circuits) is increasing rapidly. In recent years, there has been a demand for downsizing, lightening, thinning, high definition, and high functionality of electronic devices, and a mounting method using a film carrier tape for mounting electronic components that can be mounted in a small space has been adopted.

  Film carrier tapes for mounting electronic components include TAB tapes and T-BGA tapes, but COF has been put to practical use as a mounting method for mounting in a smaller space and higher density.

  The COF is a composite part in which a bare semiconductor IC is directly mounted on a film-like wiring board. In many cases, the COF is used by being connected to a larger rigid wiring board or display board. And a film-like wiring board is made from the laminated board which laminated | stacked organic polymer films, such as a polyimide, and metal foil.

  A film-like wiring board is obtained by laminating a photosensitive resin layer on the metal foil surface of a metal foil laminate, performing exposure corresponding to the desired wiring pattern, photocuring the photosensitive resin of the required part, and developing. After removing the photosensitive resin in the unexposed portion, the coated metal layer of the substrate not covered with the cured resist is removed by etching, or the plating metal is deposited on the portion not covered with the cured resist by plating. Finally, a method is adopted in which the cured resist is removed by peeling to obtain a wiring board having a desired conductor pattern. As a method of laminating the photosensitive resin, there are a method of applying and drying a liquid resist and a method of laminating the photosensitive resin laminate.

  As a laminate for COF, a polyimide copper clad laminate obtained mainly by sputtering copper on a polyimide resin film has been used. In the case of the sputtering method, since the yield is likely to deteriorate due to the pinhole of the metal layer, a polyimide metal laminate without a pinhole is desired. As a metal laminated board without a pinhole, there exists what laminated | stacked the stainless steel foil, the rolled copper foil, the electrolytic copper foil, and the polyimide. This laminate is obtained by laminating polyimide on a copper foil by casting or laminating methods, but there is one in which a thermoplastic polyimide layer is formed on a metal foil in order to improve adhesive strength and the like.

  On the other hand, IC chip mounting can be performed at low temperatures such as ACF, NCP, and ultrasonic bonding, and mounting at high temperatures of 300 ° C or higher such as Au-Au bonding and Au-Sn bonding. Au-Au junctions and Au-Sn junctions are often used from the point of view of system and chip / wiring connection reliability.

  In the case of a polyimide laminate obtained by sputtering, there is no thermoplastic resin layer, so the phenomenon that metal wiring sinks into the polyimide layer does not occur when chip mounting at 300 ° C or higher, but the adhesion to the conductor is inferior There are problems as described above.

  When a polyimide layer is laminated on a copper foil by coating or pressure bonding, it is generally necessary to use a thermoplastic polyimide in order to increase the adhesion between the copper foil and the polyimide layer and to impart heat resistance. However, when the chip was mounted at a temperature of 300 ° C. or higher, there was a problem that the thermoplastic polyimide layer was thermally deformed and the conductor was sunk into the thermoplastic polyimide layer.

JP 2004-17349 A JP 2000-58989 A Japanese Patent No. 2729063

  In Patent Document 1, a specific thermoplastic polyimide layer is formed as a stainless steel etching stop layer on both surfaces of a non-thermoplastic polyimide layer, and stainless steel 304 is laminated on both surfaces of the thermoplastic resin layer. A polyimide metal laminate for a suspension for a hard disk drive having excellent adhesion to a metal foil and a fine workability, wherein the thickness of the thermoplastic polyimide layer is 0.5 to 10 μm (Example 7 μm) Is described.

  In Patent Document 2, in a metal laminate using an adhesive sheet having a three-layer structure in which an adhesive layer is formed on both sides of a base film as an insulating layer, the base film has a hygroscopic expansion coefficient of 20 ppm or less, and an adhesive. A flexible metal foil laminate having improved moisture absorption characteristics, characterized in that the layer thickness is 5 μm or less (Example: 2 to 3 μm) is described.

  In Patent Document 3, the thickness of the adhesive polyimide film layer that is in direct contact with the metal foil and has a glass transition temperature of 170 ° C. or higher and the thickness of the polyimide film layer that has a glass transition temperature of 300 ° C. or higher and 500 ° C. or lower. A ratio of 0.001 or more and 0.2 or less (Example: 4 to 5 μm), and polyimide or a precursor thereof dissolved in a solvent is sequentially applied onto a metal foil, and then heated to form two or more films. A method for producing a flexible metal foil laminate characterized by forming a layer is described.

  As described above, it has been disclosed to reduce the thickness of the thermoplastic or adhesive polyimide layer in contact with the conductor to some extent, but in the case of flip chip mounting using Au-Sn eutectic in the COF manufacturing process, 300 Since it is exposed to high temperature and high pressure of ℃ or higher, there is a problem that the thermoplastic or adhesive polyimide is thermally deformed and the conductor sinks.

  The present invention is excellent in dimensional stability and adhesion to the conductor, prevents the conductor from sinking into the polyimide layer during the Au-Sn eutectic in the COF manufacturing process, and improves the connection reliability between the electronic component and the film carrier tape. An object of the present invention is to provide an improved COF laminate and a COF film carrier tape.

  The present invention is a COF laminate in which a conductor is laminated on one side or both sides of an insulating layer, wherein the insulating layer has a multilayer structure composed of a plurality of polyimide resins, and the insulating layer has a linear expansion coefficient of 20 ppm / ° C. or less. The non-thermoplastic polyimide layer has a structure in which one or both sides are laminated with a thermoplastic polyimide layer, and the thickness of the thermoplastic polyimide layer in contact with the conductor is 2.0 μm or less, and this thermoplastic polyimide layer The COF laminate is characterized by having a glass transition temperature of 300 ° C. or higher. Further, the present invention is a COF film carrier tape obtained by processing the above-mentioned COF laminate.

The present invention is further described below.
The COF laminate comprises a metal foil serving as a conductor and a multi-layered polyimide layer serving as an insulating layer, and the metal foil may be on one side or both sides. The insulating layer has at least one non-thermoplastic polyimide layer and one thermoplastic polyimide layer, and the polyimide layer in contact with the conductor is a thermoplastic polyimide layer.

  The material of the metal foil to be used is not limited, and examples thereof include stainless steel, copper, iron, and aluminum, but copper or copper alloy is excellent. Although there is no restriction | limiting in the thickness of metal foil, It is good to select from the range of 5-50 micrometers.

  The non-thermoplastic polyimide layer has a linear thermal expansion coefficient of 20 ppm / ° C. or less, and 10 ppm / ° C. or more and 20 ppm / ° C. or less is suitable. The linear thermal expansion coefficient is measured by an average linear thermal expansion coefficient from 100 ° C. to 250 ° C. using a thermomechanical analyzer.

  Although there is no restriction | limiting in particular as a non-thermoplastic polyimide which forms a non-thermoplastic polyimide layer, The polyimide synthesize | combined from specific diamine and specific tetracarboxylic dianhydride can utilize preferably.

  Such diamines include o-phenylenediamine, p-phenylenediamine, m-phenylenediamine, 4,4'-diaminophenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diamino. -Biphenyl, 4,4'-diamino-2,2'-dimethylbiphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, may have a substituent such as an alkyl group or an alkoxy group Good 4,4′-diamino-benzanilide and the like. These may be used alone or in combination of two or more. Moreover, although it can be used in combination with other diamines, the amount of the diamine component used is preferably 70 mol% or more.

  Examples of such tetracarboxylic dianhydrides include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic acid, and the like. Can be mentioned. These may be used alone or in combination of two or more. Further, although it can be used in combination with other tetracarboxylic dianhydrides, the amount of the tetracarboxylic acid component used is preferably 70 mol% or more.

  Furthermore, as the non-thermoplastic polyimide for forming the non-thermoplastic polyimide layer, a commercially available non-thermoplastic polyimide film, a polyimide solution as an intermediate thereof, or a precursor solution thereof can be used. For example, Upilex (registered trademark) S, SGA, SN of Ube Industries, Ltd., Kapton (registered trademark) H, V, EN of Toray DuPont Co., Ltd., Apical (registered trademark) AH, NPI of Kaneka Corporation And films such as HP and intermediates thereof.

  The thickness of the non-thermoplastic polyimide layer is not particularly limited, but 2 to 100 μm, preferably 5 to 50 μm is suitable.

  The thermoplastic polyimide layer in contact with the conductor has a thickness of 2.0 μm or less, preferably 0.5 μm or more and 2.0 μm or less, and has a glass transition temperature of 300 ° C. or more that can be measured with a dynamic viscoelasticity measuring apparatus. It is necessary to be. In addition, when it has a thermoplastic polyimide layer on both surfaces, they may be the same or different, but when it has a conductor on both surfaces, it is desirable that all satisfy the above physical property values.

  The thermoplastic polyimide forming the thermoplastic polyimide layer is not particularly limited, but a polyimide synthesized from a specific diamine and a specific tetracarboxylic dianhydride can be preferably used.

  Such diamines include 1,3-bis (3-aminophenoxy) benzene, 4,4'-bis (3-aminophenoxy) biphenyl, 3,3'-diaminobenzophenone, 2,2-bis (4- (4- Aminophenoxy) phenyl) propane and the like. These may be used alone or in combination of two or more. Moreover, although it can be used in combination with other diamines, the amount of the diamine component used is preferably 70 mol% or more.

  Examples of such tetracarboxylic dianhydrides include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic acid, and the like. Can be mentioned. These may be used alone or in combination of two or more. Moreover, although it can be used in combination with other tetracarboxylic dianhydrides, the amount of the tetracarboxylic acid used is preferably 70 mol% or more.

  The laminated sheet for COF of the present invention is applied to the surface of the metal foil with a thermoplastic polyimide or a precursor solution thereof, then applied with a non-thermoplastic polyimide or a precursor solution thereof (hereinafter also referred to as a varnish), dried, It can be produced by a curing method. As a method for applying the varnish, known methods such as a die coater, a comma coater, a roll coater, a gravure coater, a curtain coater, and a spray coater can be employed. In this case, if necessary, thermoplastic polyimide or a precursor solution thereof (hereinafter also referred to as varnish) can be applied in multiple layers. As a method for drying and curing the applied varnish, a normal heating and drying furnace can be used. As the atmosphere in the drying furnace, air, inert gas (nitrogen, argon), or the like can be used. As the drying and curing temperature, a temperature range of about 60 ° C to 400 ° C is preferably used. Curing is performed until the polyimide precursor becomes polyimide. In addition, when copper foil thickness is large, copper foil thickness is made into predetermined thickness by an etching process etc. as needed.

  A laminated board having metal foils on both sides is manufactured by making the insulating layer into three or more layers, using the outermost layer as a thermoplastic polyimide layer, and thermocompression bonding the metal foil to the surface of the outermost thermoplastic polyimide layer. .

  In addition, the COF laminate of the present invention is obtained by applying a thermoplastic polyimide or a precursor solution thereof on one or both sides of a non-thermoplastic polyimide film, and obtaining a multilayer polyimide film in the same manner as described above. It can be manufactured by thermocompression bonding a metal foil to the surface of the polyimide layer.

  Although there is no restriction | limiting in particular about the method of carrying out thermocompression bonding, For example, well-known methods, such as a hot press method and a thermal laminating method, are employable.

  Methods for producing a COF film carrier tape from a COF laminate are known, and these methods can be appropriately selected and used. For example, a COF laminate is cut into a film with a predetermined width, sprockets are provided on both sides of the film, a photosensitive resin layer is provided on the metal foil side, and exposure is performed through a mask that provides a predetermined circuit. Then, an etching process is performed to remove either the unexposed part or the exposed part. Next, there is a method of forming a circuit pattern by etching the exposed metal foil using the remaining resin layer as a resist, and further removing the resist as necessary to obtain a COF film carrier tape.

With the present invention, heat resistance and adhesiveness are excellent, there is no pinhole, wiring displacement is small even during chip mounting by Au-Au bonding or Au-Sn bonding, underfill filling is possible, and electronic components and film carrier tapes It is possible to provide a COF laminate and a COF film carrier tape that can improve connection reliability.
In other words, the insulating layer has a structure in which one or both sides of a non-thermoplastic polyimide layer are laminated with a thermoplastic polyimide layer, and the thickness of the thermoplastic polyimide layer in contact with the conductor is 2.0 μm or less. Even in the case of flip chip mounting using Au-Sn eutectic at 300 ° C or higher, it prevents thermal deformation and prevents the conductor from sinking into the polyimide layer. And improving the connection reliability between the electronic component and the film carrier tape.

FIG. 1 is a cross-sectional view for explaining the layer structure of a single-sided conductor COF laminate, which includes an insulating layer 10 and a conductor 20. The insulating layer 10 is composed of three layers of a thermoplastic polyimide layer 11, a non-thermoplastic polyimide layer 12, and a thermoplastic polyimide layer 13. The thermoplastic polyimide layer 13 is in contact with the conductor 20.
FIG. 2 is a conceptual diagram showing an example in which an IC chip is mounted on a COF film carrier tape. A circuit in which a gold-plated bump 2 of an IC chip 1 is formed on a polyimide layer 3 of a COF film carrier tape. 4 shows the state of joining. At this time, since the thermocompression bonding is performed at a high temperature of about 350 to 400 ° C., the thickness of the polyimide layer 3 in the crimping portion sinks from the initial thickness T1 to T2. It is desired to reduce this thickness difference T1-T2 as much as possible.

Hereinafter, the present invention will be described in more detail with reference to examples.
Abbreviations used in the examples are as follows.
PMDA: pyromellitic anhydride
BPDA ... 3,3 ', 4,4'-biphenyltetracarboxylic acid
DAPE ... 4,4'-diamino-diphenyl ether
MT ・ ・ ・ ・ ・ ・ 4,4'-Diamino-2,2'-dimethylbiphenyl
BAPP ... 2,2-bis (4- (4-aminophenoxy) phenyl) propane
TPE ・ ・ ・ 1,3-bis (4-aminophenoxy) benzene
DMAc ... dimethylacetamide

Example 1
In DMAc425g, MT18.719g and DAPE11.760g were dissolved in a 1 L separable flask with stirring. Next, 25.305 g of PMDA and 8.532 g of BPDA were added little by little to this solution, and a polymerization reaction was performed to obtain a high-viscosity non-thermoplastic polyimide precursor solution A. As a result of measuring the viscosity with a B-type viscometer, it was 255 poise at 23 ° C.
Similarly, after 43.150 g of BAPP was dissolved in 425 g of DMAc, PMDA 19.087 g and BPDA 4.543 g were added to this solution, and a polymerization reaction was performed to obtain a high-viscosity thermoplastic polyimide precursor solution B. As a result of measuring the viscosity, it was 40 poise at 23 ° C.

Next, the polyimide precursor solution B obtained above was bar-coated on an electrolytic copper foil with a thickness of 18 μm (NA-VLP manufactured by Mitsui Metal Mine Co., Ltd.) so that the film thickness after imide conversion would be 1 μm. did. Thereafter, it was dried at 130 ° C. for 5 minutes. Thereafter, the polyimide precursor solution A was bar-coated on the dried polyimide layer so as to be laminated so that the film thickness after imide conversion was 37 μm, and dried at 130 ° C. for 5 minutes. Similarly, the polyimide precursor solution B was bar-coated on this film so that the thickness after imide conversion was 1 μm, and dried at 130 ° C. for 5 minutes.
Next, the dried laminate was put into a vacuum thermostat and subjected to heat treatment at 200 ° C. for 30 min, 300 ° C. for 30 min, and 350 ° C. for 30 min to obtain a COF laminate having a polyimide layer thickness of 39 μm. Here, the linear expansion coefficient of the non-thermoplastic polyimide A layer obtained from the polyimide precursor solution A was 15 ppm / ° C. The glass transition temperature of the thermoplastic polyimide B layer obtained from the polyimide precursor solution B was 310 ° C. The glass transition temperature was measured by dynamic viscoelasticity, and the peak value of the loss modulus was taken as the glass transition temperature.

  A 60 μm pitch wiring pattern was formed on the obtained COF laminate and used as a COF film carrier tape. The inner lead portion is tinned. Thereafter, an IC having gold bumps was mounted on the inner lead portion of the COF film carrier tape. For mounting, flip chip bonder “TFC-2100” manufactured by Shibaura Mechatronics Co., Ltd. is used, bonding head tool temperature is 400 ° C, stage temperature is 100 ° C, and bonding pressure is 20 gf per bump. It was.

  Next, the cross section of the COF film carrier tape on which the IC was mounted was observed and measured as T1 (film thickness) −T2 (mounting part film thickness) = T3 (resin deformation amount due to mounting) shown in FIG. In this example, T3 was 1 μm, and the connection between the inner lead and the bump was good.

Example 2
MT28.078g and TPE4.297g were dissolved in DMAc425g with stirring in a 1 L separable flask. Next, 25.305 g of PMDA and 8.532 g of BPDA were added little by little to this solution, and a polymerization reaction was performed to obtain a high viscosity non-thermoplastic polyimide precursor solution C. As a result of measuring the viscosity with a B-type viscometer, it was 320 poise at 23 ° C.

  Similarly, after 43.150 g of BAPP was dissolved in 425 g of DMAc, 21.333 g of PMDA and 1.514 g of BPDA were added to this solution, and a polymerization reaction was performed to obtain a thermoplastic polyimide precursor solution D having a high viscosity. As a result of measuring the viscosity, it was 20 poise at 23 ° C.

  Thereafter, the same operation as in Example 1 was performed to obtain a COF laminate having a polyimide layer thickness of 39 μm. The obtained non-thermoplastic polyimide C layer had a linear expansion coefficient of 13 ppm / ° C., and the thermoplastic polyimide layer D had a glass transition temperature of 310 ° C. As a result of processing into a COF film carrier tape and mounting the IC, T3 was 0.5 μm, and the connection between the inner lead and the bump was good. The thickness of the polyimide layer is 1 μm / 37 μm / 1 μm in the order of D / C / D.

Example 3
Except that the non-thermoplastic polyimide A layer was 21 μm and the thermoplastic polyimide B layers on both sides were 2 μm, it was processed into a COF film carrier tape in the same manner as in Example 1 and the IC was mounted.As a result, T3 was 1.5 μm. The connection between the inner lead and the bump was good.

Comparative Example 1
Except that the non-thermoplastic polyimide A layer was 30 μm and the thermoplastic polyimide B layers on both sides were 5 μm, respectively, the COF film carrier tape was processed in the same manner as in Example 1 and the IC was mounted.As a result, T3 was 4 μm. Thus, the deformation of the resin in the vicinity of the inner lead was large, and the connection state between the inner lead and the bump was poor.

Comparative Example 2
MT23.781g and TPE8.594g were dissolved in DMAc425g with stirring in a 1 L separable flask. Next, 25.305 g of PMDA and 8.532 g of BPDA were added little by little to this solution, and a polymerization reaction was performed to obtain a high-viscosity non-thermoplastic polyimide precursor solution E. As a result of measuring the viscosity with a B-type viscometer, it was 230 poise at 23 ° C. Next, using the thermoplastic polyimide precursor solution D obtained in Example 2 and the non-thermoplastic polyimide precursor solution E described above, the same operation as in Example 1 was performed, and the thickness of the polyimide layer was 39 μm for COF. A laminate was obtained. The obtained non-thermoplastic polyimide E layer had a linear expansion coefficient of 30 ppm / ° C. As a result of mounting on the COF film carrier tape, T3 was 0.5 μm, but the inner leads and bumps were misaligned due to the thermal dimension change of the tape, and the connection state was poor.

Comparative Example 3
37.621 g of TPE was dissolved in 425 g of DMAc with stirring in a 1 L separable flask. Next, 37.379 g of BPDA was gradually added to this solution to carry out a polymerization reaction, and a high-viscosity thermoplastic polyimide precursor solution F was obtained. As a result of measuring the viscosity with a B-type viscometer, it was 120 poise at 23 ° C. Next, the polyimide precursor solution F obtained above is bar-coated on an electrolytic copper foil NA-VLP (made by Mitsui Mining Co., Ltd.) having a thickness of 18 μm so that the film thickness after imide conversion becomes 1 μm. did. Thereafter, it was dried at 130 ° C. for 5 minutes. Thereafter, the polyimide precursor solution A of Example 1 was bar-coated so as to be laminated on the dried polyimide layer so that the film thickness after imide conversion was 37 μm, and dried at 130 ° C. for 5 minutes. Similarly, the polyimide precursor solution F was bar-coated on this film so that the thickness after imide conversion was 1 μm, and dried at 130 ° C. for 5 minutes.
The laminated body thus obtained was put into a vacuum thermostat and subjected to heat treatment at 200 ° C. for 30 minutes, 300 ° C. for 30 minutes, and 350 ° C. for 30 minutes to obtain a multilayer substrate for COF with a polyimide layer thickness of 39 μm. .

  The glass transition temperature of the thermoplastic polyimide F produced from the polyimide precursor solution F was 220 ° C. The COF film carrier tape was processed in the same manner as in Example 1 and the IC was mounted. As a result, T3 was 2.0 μm, but the resin deformation near the inner leads was large, and some inner leads were peeled off from the film. The connection between the inner lead and the bump was poor.

Cross section of laminated sheet for COF Conceptual diagram showing an example of mounting an IC chip on a COF film carrier tape

Explanation of symbols

1: IC chip, 2: Bamboo, 3: Polyimide layer, 4: Circuit, 10: Insulating layer, 11, 13: Thermoplastic polyimide layer, 12: Non-thermoplastic polyimide layer, 20: Conductor

Claims (4)

  In a COF laminate in which a conductor is laminated on one or both sides of an insulating layer, the insulating layer has a multilayer structure composed of a plurality of polyimide resins, and the insulating layer has a linear expansion coefficient of 20 ppm / ° C. or less. A structure in which one or both sides of a polyimide layer are laminated with a thermoplastic polyimide layer, the thickness of the thermoplastic polyimide layer in contact with the conductor is 2.0 μm or less, and the glass transition temperature of the thermoplastic polyimide layer is 300 COF laminates that are at or above ℃.   2. The COF laminate according to claim 1, wherein the insulating layer is obtained by directly applying a polyimide precursor solution to a conductor, thermosetting and imide conversion.   The laminate for COF according to claim 1, wherein the insulating layer is obtained by thermocompression bonding a polyimide resin film to a conductor.   The COF film carrier tape obtained by processing the laminated board for COF in any one of Claims 1-3.