JP2005161632A - Manufacturing method of flexible metal clad laminated sheet enhanced in dimensional stability and flexible metal clad laminated sheet obtained thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible metal clad laminated sheet excellent in dimensional stability, and its manufacturing method. <P>SOLUTION: In the flexible metal clad laminated sheet by laminating a polyimide film and a metal foil through an adhesive layer containing a thermoplastic polyimide, the adhesive layer containing the thermoplastic polyimide is provided on one side of the metal foil before laminating the polyimide film on the metal foil. The flexible metal clad laminated sheet obtained by this manufacturing method is also disclosed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a flexible metal-clad laminate obtained by providing an adhesive layer containing a thermoplastic polyimide on one surface of a metal foil and then bonding a polyimide film to the adhesive layer, and a method for producing the same. More specifically, a flexible film obtained by bonding a metal foil with an adhesive layer obtained by casting and applying a solution containing polyamic acid, which is a precursor of thermoplastic polyimide, onto a metal foil, followed by imidization, and a polyimide film. A metal-clad laminate, and a method for producing the same, and preferably the dimensional change rate before and after removing the metal foil, and the total value of the dimensional change rate before and after heating at 250 ° C. for 30 minutes after removing the metal foil, The present invention relates to a flexible metal-clad laminate having a longitudinal direction (hereinafter also referred to as MD direction) and a width direction (hereinafter also referred to as TD direction) in the range of −0.08 to +0.08, and a method for producing the same.

  In recent years, the demand for various printed circuit boards has increased along with the reduction in weight, size and density of electronic products. In particular, the demand for flexible laminates (also referred to as flexible printed circuit boards (FPCs), etc.) has increased. ing. The flexible laminate has a structure in which a circuit made of a metal foil is formed on an insulating film.

  The flexible laminate is generally formed of various insulating materials, and a flexible insulating film is used as a substrate, and a metal foil is bonded to the surface of the substrate by heating and pressure bonding via various adhesive materials. Manufactured by. A polyimide film or the like is preferably used as the insulating film. As the adhesive material, a thermosetting adhesive such as epoxy or acrylic is generally used (FPC using these thermosetting adhesives is hereinafter also referred to as three-layer FPC).

  Thermosetting adhesives have the advantage that they can be bonded at relatively low temperatures. However, in the future, as required characteristics such as heat resistance, flexibility, and electrical reliability become stricter, it is considered that it is difficult to cope with a three-layer FPC using a thermosetting adhesive. On the other hand, an FPC (hereinafter also referred to as a two-layer FPC) in which a metal layer is directly provided on an insulating film or a thermoplastic polyimide is used for an adhesive layer has been proposed. This two-layer FPC has characteristics superior to those of the three-layer FPC, and demand is expected to increase in the future.

  As a method for producing a flexible metal-clad laminate for use in a two-layer FPC, a polyamic acid, which is a polyimide precursor, is cast on a metal foil, applied, and then casted directly onto a polyimide film by sputtering or plating. Examples thereof include a metallizing method for providing a metal layer and a laminating method for bonding a polyimide film and a metal foil through a thermoplastic polyimide. Among these, the lamination method is superior in that the thickness range of the metal foil that can be handled is wider than that of the casting method and the apparatus cost is lower than that of the metalizing method. As a device for laminating, a hot roll laminating device or a double belt press device for continuously laminating a roll-shaped material is used. Of these, the hot roll laminating method can be used more preferably from the viewpoint of productivity.

  When a conventional three-layer FPC was produced by a laminating method, a thermosetting resin was used for the adhesive layer, so that the laminating temperature could be less than 200 ° C. (see Patent Document 1). On the other hand, since the two-layer FPC uses thermoplastic polyimide as an adhesive layer, it is necessary to apply a high temperature of 200 ° C. or higher, and in some cases, close to 400 ° C., in order to develop heat-fusibility. Therefore, residual distortion occurs in the flexible metal-clad laminate obtained by laminating, and it appears as a dimensional change when wiring is formed by etching and when solder reflow is performed to mount components.

  In particular, in the laminating method, when an adhesive layer containing a thermoplastic polyimide is provided on a polyimide film, the polyamic acid which is a precursor of the thermoplastic polyimide is cast and applied, and then continuously heated to imidize, Since the heating and pressurization is continuously performed when the metal foil is bonded, the material is often placed in a heating environment under tension. Therefore, different thermal stresses are generated in the MD direction and the TD direction. Specifically, a pulling force acts in the MD direction where tension is applied, and conversely, a shrinking force acts in the TD direction. As a result, when the metal foil is etched from the flexible laminate and when heated through solder reflow, this strain is released, the MD direction contracts, and conversely, the TD direction expands.

In recent years, in order to achieve miniaturization and weight reduction of electronic devices, wiring provided on a substrate has been miniaturized, and components to be mounted are mounted with miniaturization and high density. For this reason, if the dimensional change after forming the fine wiring is increased, there is a problem that the component and the board are not well connected due to deviation from the component mounting position in the design stage.
Therefore, attempts have been made to suppress dimensional changes by controlling the laminating pressure or controlling the tension of the adhesive film (see Patent Document 2 or 3). However, although the dimensional change is improved by these means, it is not sufficient yet, and further improvement of the dimensional change is demanded.
JP-A-9-199830 JP 2002-326308 A JP 2002-326280 A

  The present invention has been made in view of the above-mentioned problems, and its purpose is to suppress the occurrence of dimensional change when produced by a flexible metal-clad laminate, particularly the laminate method, in which the occurrence of dimensional change is suppressed. The object is to provide a flexible metal-clad laminate and a method for producing the same.

  As a result of intensive studies in view of the above problems, the present inventors have provided an adhesive layer containing a thermoplastic polyimide on a metal foil that has a higher elastic modulus than a polyimide film and is less susceptible to the influence of tension. Thus, the inventors have uniquely found that the generation of thermal stress during the imidization and lamination of thermoplastic polyimide can be alleviated and the occurrence of dimensional change can be effectively suppressed, and the present invention has been completed.

  That is, the first of the present invention is a method for producing a flexible metal-clad laminate in which a polyimide film and a metal foil are bonded via an adhesive layer containing a thermoplastic polyimide, and thermoplastic polyimide is applied to one side of the metal foil. The present invention relates to a method for producing a flexible metal-clad laminate, which is obtained by providing a containing adhesive layer and then laminating with a polyimide film.

  A preferred embodiment is characterized in that when a bonding layer is provided on one side of a metal foil, a solution containing a polyamic acid that is a precursor of a thermoplastic polyimide is cast and applied, and then imidized. It relates to a manufacturing method.

  A further preferred embodiment relates to the above production method, characterized in that it is obtained by laminating a metal foil with an adhesive layer and a polyimide film using a hot roll laminating apparatus having a pair of metal rolls.

  2nd of this invention is related with the flexible metal-clad laminated board obtained by the said manufacturing method.

  In a preferred embodiment, the dimensional change rate before and after removing the metal foil, and the total value of the dimensional change rate before and after heating at 250 ° C. for 30 minutes after removing the metal foil is −0.08 in both the MD direction and the TD direction. It is related with the said flexible metal-clad laminated board characterized by being in the range of-+ 0.08.

  In the flexible metal-clad laminate obtained from the production method of the present invention, the occurrence of dimensional change is suppressed, and in particular, the occurrence of dimensional change in the laminating method can also be effectively suppressed. Specifically, the dimensional change rate before and after removing the metal foil and the total value of the dimensional change rate before and after heating at 250 ° C. for 30 minutes after removing the metal foil are −0.08 in both the MD direction and the TD direction. It can be in the range of ~ + 0.08. Therefore, it can be suitably used for an FPC or the like in which fine wiring is formed, and problems such as misalignment can be improved.

  One embodiment of the present invention will be described below.

  The method for producing a flexible metal-clad laminate according to the present invention is characterized in that an adhesive layer containing a thermoplastic polyimide is provided on one side of a metal foil and then bonded to a polyimide film.

  The metal foil to be used is not particularly limited, but when the flexible metal-clad laminate of the present invention is used for electronic equipment / electric equipment, for example, copper or copper alloy, stainless steel or its alloy, nickel Alternatively, a foil made of a nickel alloy (including 42 alloy), aluminum, or an aluminum alloy can be used. In general flexible metal-clad laminates, copper foil such as rolled copper foil and electrolytic copper foil is frequently used, but it can also be preferably used in the present invention. In addition, the antirust layer, the heat-resistant layer, or the contact bonding layer may be apply | coated to the surface of these metal foil.

  In the present invention, the thickness of the metal foil is not particularly limited, and may be any thickness as long as a sufficient function can be exhibited depending on the application. Further, the surface roughness of the metal foil is not particularly limited and can be selected as appropriate. However, in recent years when the wiring is miniaturized, the surface on the side in contact with the adhesive layer (hereinafter also referred to as M-plane). It is preferable to use a metal foil having the lowest possible roughness. The surface roughness is generally expressed by ten-point average roughness (Rz) and centerline average roughness (Ra), and the smaller these values are, the lower the roughness of the metal foil.

  As the thermoplastic polyimide contained in the adhesive layer provided on the metal foil, thermoplastic polyimide, thermoplastic polyamideimide, thermoplastic polyetherimide, thermoplastic polyesterimide, and the like can be suitably used. Among these, thermoplastic polyesterimide is particularly preferably used from the viewpoint of low moisture absorption characteristics.

  In view of the fact that lamination with an existing apparatus is possible and the heat resistance of the resulting metal-clad laminate is not impaired, the thermoplastic polyimide in the present invention has a glass transition temperature (150 to 300 ° C.). Tg) is preferred. In addition, Tg can be calculated | required from the value of the inflexion point of the storage elastic modulus measured with the dynamic viscoelasticity measuring apparatus (DMA).

  In the method for producing a flexible metal-clad laminate according to the present invention, a solution containing polyamic acid, which is a precursor of thermoplastic polyimide, is applied onto a metal foil, imidized, and then bonded to a polyimide film. The polyamic acid used at that time is not particularly limited, and any known polyamic acid can be used. Also for the production, known raw materials, reaction conditions, and the like can be used (for example, see Examples described later). Moreover, you may add an inorganic or organic filler as needed.

  The method for casting and coating the solution containing the polyamic acid on a metal foil is not particularly limited, and existing methods such as a die coater, a reverse coater, a gravure coater, and a blade coater can be used. The coating thickness is not particularly limited and may be adjusted appropriately for each application. However, if the coating thickness becomes too thick, the time required for curing becomes long, so that the adhesive layer thickness after imidization becomes 10 μm or less. It is preferable to apply to. Also, if the difference in coefficient of linear expansion between the metal foil and the polyimide layer increases, it will affect the dimensional change, so it is better to set the adhesive layer thickness taking into account the linear expansion coefficient and thickness of the polyimide film that is the core. good.

  In general, polyimide is obtained by imidizing a polyamic acid which is a precursor thereof, and a thermal cure method or a chemical cure method is used for imidization. The thermal cure method is a method in which an imidization reaction proceeds only by heating without causing a dehydrating ring-closing agent or the like to act. The chemical cure method is a method in which a chemical conversion agent and / or a catalyst is applied to a polyamic acid solution. This is a method for promoting imidization.

  The chemical conversion agent means a dehydrating ring-closing agent for polyamic acid, for example, aliphatic acid anhydride, aromatic acid anhydride, N, N′-dialkylcarbodiimide, halogenated lower aliphatic, halogenated lower fatty acid anhydride. Products, arylphosphonic acid dihalides, thionyl halides, or a mixture of two or more thereof. Among these, from the viewpoint of easy availability and cost, aliphatic acid anhydrides such as acetic anhydride, propionic anhydride, and lactic acid anhydride, or a mixture of two or more thereof can be preferably used.

  Further, the catalyst means a component having an effect of promoting dehydration ring-closing action on polyamic acid, and examples thereof include aliphatic tertiary amines, aromatic tertiary amines, and heterocyclic tertiary amines. . Among them, those selected from heterocyclic tertiary amines are particularly preferably used from the viewpoint of reactivity as a catalyst. Specifically, quinoline, isoquinoline, β-picoline, pyridine and the like are preferably used.

An acid anhydride, which is a dehydrating agent, generates an acid as a by-product when it reacts with water. Therefore, when it comes into contact with the metal foil, there is a possibility that the surface of the metal foil undergoes a chemical change and deteriorates. Therefore, in the present invention, it is preferable to imidize the thermoplastic polyimide by a thermal curing method. The higher the temperature of the heat curing, the easier the imidization occurs, so the curing speed can be increased, which is preferable in terms of productivity. However, if it is too high, the thermoplastic polyimide may cause thermal decomposition.
On the other hand, if the temperature of the heat curing is too low, imidization is difficult to proceed, and the time required for the curing process becomes long. The temperature of the thermal curing is preferably set in the range of glass transition temperature to glass transition temperature + 200 ° C of the thermoplastic polyimide, and more preferably in the range of glass transition temperature + 50 ° C to glass transition temperature + 150 ° C. . Further, regarding the imidization time, it is sufficient to take a time sufficient for the imidization and drying to be substantially completed, and it is not limited uniquely, but generally in the range of about 1 to 600 seconds. Set as appropriate. Moreover, in order to improve the melt fluidity of the adhesive layer, it is possible to intentionally lower the imidization rate and / or leave the solvent.

  When a metal foil is supplied in a roll state and an adhesive layer is applied and imidized, tension is applied from the viewpoint of transportability and winding, and the tension applied to the metal foil at that time is 5 N / m to 200 N / m. It is preferable to set it within the range of 10 N / m to 150 N / m. When the tension is smaller than the above range, sagging may occur during conveyance, which may cause problems such as being unable to wind evenly. On the other hand, if it is larger than the above range, even if a metal foil is used, the influence of the tension becomes strong, and since a strong tension is applied at a high temperature, there is a possibility that a thermal stress is generated and affects the dimensional change.

  The flexible metal-clad laminate according to the present invention is obtained by laminating the metal foil with an adhesive layer and a polyimide film. The kind of polyimide film to be bonded is not particularly limited, and a conventionally known film can be used. Examples of commercially available polyimide films include apical (manufactured by Kaneka Chemical Co., Ltd.), kapton (manufactured by DuPont), and upilex (manufactured by Ube Industries). Of these, Apical HP (manufactured by Kaneka Chemical Co., Ltd.) can be preferably used from the viewpoint of elastic modulus, linear expansion coefficient, and water absorption.

  In addition to the commercially available film, a polyamic acid obtained using a conventionally known raw material can be imidized and used. For imidization, a thermal cure method and a chemical cure method can be used in the same manner as the thermoplastic polyimide. The thermal curing method or the chemical curing method may be imidized alone or in combination with the chemical curing method and the thermal curing method. Especially, it is preferable to imidize by a chemical cure method from the point of the toughness of a film, breaking strength, and productivity. The reaction conditions for imidation are not particularly limited, and may vary depending on the type of polyamic acid, film thickness, thermal curing method and / or chemical curing method, and the like. Moreover, you may add an inorganic or organic filler to a polyamic acid as needed.

  For the bonding of the metal foil with an adhesive layer and the polyimide film in the present invention, for example, a hot roll laminating apparatus having a pair of metal rolls or a continuous treatment by a double belt press (DBP) can be used. Among these, it is preferable to use a hot roll laminating apparatus having a pair of metal rolls because the apparatus configuration is simple and advantageous in terms of maintenance cost. The “heat roll laminating apparatus having a pair of metal rolls” herein may be an apparatus having a metal roll for heating and pressurizing a material, and the specific apparatus configuration is particularly limited. It is not a thing.

  The specific configuration of the means for carrying out the thermal lamination is not particularly limited, but a protective material is disposed between the pressing surface and the metal foil in order to improve the appearance of the resulting laminate. It is preferable to do. The protective material is not particularly limited as long as it can withstand the heating temperature in the heat laminating process, and preferably a heat-resistant plastic such as a non-thermoplastic polyimide film, a metal foil such as a copper foil, an aluminum foil, or a SUS foil. Can be used. Among these, a non-thermoplastic polyimide film is more preferably used from the viewpoint of excellent balance between heat resistance and reuse. In addition, if the thickness is thin, the function of buffering and protecting at the time of lamination will not be sufficiently fulfilled, so the thickness of the non-thermoplastic polyimide film is preferably 75 μm or more.

  The heating method of the material to be laminated in the heat laminating means is not particularly limited. For example, heating using a conventionally known method capable of heating at a predetermined temperature, such as a heat circulation method, a hot air heating method, an induction heating method, or the like. Means can be used. Similarly, the pressurization method of the material to be laminated in the heat laminating means is not particularly limited, and a conventionally known method capable of applying a predetermined pressure such as a hydraulic method, a pneumatic method, a gap pressure method, etc. The pressurizing means adopting can be used.

  The heating temperature in the thermal laminating step, that is, the laminating temperature, is preferably a glass transition temperature (Tg) of the adhesive film + 50 ° C. or higher, and more preferably Tg + 100 ° C. or higher of the adhesive film. If it is Tg + 50 degreeC or more temperature, an adhesive film and metal foil can be heat-laminated favorably. Moreover, if it is Tg + 100 degreeC or more, the lamination speed | rate can be raised and the productivity can be improved more.

  The laminating speed in the thermal laminating step is preferably 0.5 m / min or more, and more preferably 1.0 m / min or more. If it is 0.5 m / min or more, sufficient thermal lamination is possible, and if it is 1.0 m / min or more, productivity can be further improved.

  The higher the pressure in the heat laminating step, that is, the laminating pressure, is advantageous in that the laminating temperature can be lowered and the laminating speed can be increased. There is a tendency to get worse. On the other hand, if the lamination pressure is too low, the adhesive strength of the metal foil of the laminate obtained is lowered. Therefore, the lamination pressure is preferably in the range of 49 to 490 N / cm (5 to 50 kgf / cm), and more preferably in the range of 98 to 294 N / cm (10 to 30 kgf / cm). Within this range, the three conditions of the lamination temperature, the lamination speed and the lamination pressure can be made favorable, and the productivity can be further improved.

  The tension of the metal foil with an adhesive layer during lamination is preferably 0.1 to 200 N / cm, more preferably 1 to 100 N / cm, and particularly preferably 5 to 50 N / cm. If the tension is below this range, sagging may occur during transportation, which may make it difficult to obtain a flexible metal-clad laminate with good appearance. Since the influence of tension becomes large, dimensional stability tends to be inferior.

  The polyimide film tension during lamination is preferably 0.01 to 2 N / cm, more preferably 0.02 to 1.5 N / cm, and particularly preferably 0.05 to 1.0 N / cm. If the tension is below this range, sagging may occur during transportation, which may make it difficult to obtain a flexible metal-clad laminate with good appearance. If the tension is above this range, the polyimide film will be strong in the MD direction. Lamination is performed in a pulled state, and dimensional stability tends to be inferior.

  In order to obtain the flexible metal-clad laminate according to the present invention, it is preferable to use a thermal laminating apparatus that continuously press-bonds the material to be laminated while heating, but in this thermal laminating apparatus, before the thermal laminating means, A laminated material feeding means for feeding the laminated material may be provided, or a laminated material winding means for winding the laminated material may be provided after the thermal laminating means. By providing these means, the productivity of the thermal laminating apparatus can be further improved. The specific configuration of the laminated material feeding means and the laminated material winding means is not particularly limited, and for example, an adhesive film, a metal foil, or a known roll shape capable of winding up the obtained laminated plate A winder etc. can be mentioned.

  Furthermore, it is more preferable to provide a protective material winding means and a protective material feeding means for winding and feeding the protective material. If these protective material take-up means and protective material feeding means are provided, the protective material can be reused by winding the protective material once used in the thermal laminating step and installing it again on the pay-out side. . Further, when winding up the protective material, end position detecting means and winding position correcting means may be provided in order to align both ends of the protective material. As a result, the end portions of the protective material can be aligned and wound with high accuracy, so that the efficiency of reuse can be increased. The specific configurations of the protective material winding means, the protective material feeding means, the end position detecting means, and the winding position correcting means are not particularly limited, and various conventionally known devices can be used.

  In the flexible metal-clad laminate obtained by the manufacturing method according to the present invention, the dimensional change rate before and after removing the metal foil, and the total value of the dimensional change rate before and after heating at 250 ° C. for 30 minutes after removing the metal foil. However, it is very preferable that both the MD direction and the TD direction are in the range of -0.08 to +0.08. The rate of dimensional change before and after removal of the metal foil is expressed as a ratio between a difference between a predetermined dimension in the flexible metal-clad laminate before the etching process and a predetermined dimension after the etching process and a predetermined dimension before the etching process. . The dimensional change rate before and after heating is expressed as a ratio between a difference between a predetermined dimension in the flexible metal-clad laminate after the etching process and a predetermined dimension after the heating process and a predetermined dimension after the etching process.

  If the dimensional change rate is out of this range, the dimensional change at the time of component mounting becomes large after forming fine wiring in the flexible metal-clad laminate, and it will deviate from the component mounting position at the design stage. Become. As a result, there is a possibility that the component to be mounted and the board are not connected well. In other words, if the rate of dimensional change is within the above range, it can be considered that there is no problem in component mounting.

  The method for measuring the dimensional change rate is not particularly limited, and any method known in the art can be used as long as it can measure the increase or decrease in dimensions that occurs before and after the etching or heating process in the flexible metal-clad laminate. Can be used.

  Here, it is essential to measure the dimensional change rate in both the MD direction and the TD direction. When imidizing and laminating continuously, the tension is different in the MD direction and the TD direction, so a difference appears in the degree of thermal expansion / contraction and the dimensional change rate is also different. Therefore, a material having a small dimensional change rate is required to have a low change rate in both the MD direction and the TD direction. In the present invention, the dimensional change rate before and after removing the metal foil of the flexible metal-clad laminate, and the total value of the dimensional change rate before and after heating at 250 ° C. for 30 minutes after removing the metal foil are MD direction, It is very preferable that the TD direction is in the range of -0.08 to +0.08.

  In addition, the specific conditions of the etching process at the time of measuring a dimensional change rate are not specifically limited. That is, since the etching conditions differ depending on the type of metal foil and the shape of the pattern wiring to be formed, the etching process conditions for measuring the dimensional change rate in the present invention are any conventionally known conditions. Also good. Similarly, in the heating process, it is sufficient that heating is performed at 250 ° C. for 30 minutes, and specific conditions are not particularly limited.

  As described above, the flexible metal-clad laminate obtained by the manufacturing method according to the present invention can be mounted with various miniaturized and high-density components by forming a desired pattern wiring by etching the metal foil. It can be used as a flexible wiring board. Of course, the application of the present invention is not limited to this, and it goes without saying that it can be used for various applications as long as it is a laminate including a metal foil.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.

  In addition, the evaluation method of the glass transition temperature of the thermoplastic polyimide in a synthesis example, an Example, and a comparative example, the dimensional change rate of a flexible laminated board, and metal foil peeling strength is as follows.

(Glass-transition temperature)
The glass transition temperature was measured with a DMS200 manufactured by Seiko Instruments Inc. at a temperature rising rate of 3 ° C./min in a temperature range from room temperature to 400 ° C., and the inflection point of the storage elastic modulus was taken as the glass transition temperature.

(Dimensional change rate)
Based on JIS C6481, four holes were formed in the flexible laminate, and the distance of each hole was measured. Next, after carrying out an etching process to remove the metal foil from the flexible laminate, it was left in a temperature-controlled room at 20 ° C. and 60% RH for 24 hours. Then, each distance was measured about the said four holes similarly to the etching process front. The measured value of the distance between the holes before removing the metal foil was set as D1, and the measured value of the distance between the holes after removing the metal foil was set as D2, and the dimensional change rate before and after etching was obtained by the following equation.
Dimensional change rate (%) = {(D2-D1) / D1} × 100
Subsequently, the measurement sample after etching was heated at 250 ° C. for 30 minutes and then left in a constant temperature room at 20 ° C. and 60% RH for 24 hours. Then, each distance was measured about the said four holes. The measured value of the distance of each hole after heating was set to D3, and the dimensional change rate before and after heating was obtained by the following formula.
Dimensional change rate (%) = {(D3-D2) / D2} × 100
In addition, the said dimensional change rate was measured about both MD direction and TD direction.

(Stripping strength of metal foil: Adhesive strength)
A sample was prepared according to “6.5 Peel Strength” of JIS C6471, and a 5 mm wide metal foil part was peeled off at a peeling angle of 180 degrees and 50 mm / min, and the load was measured.

(Synthesis Example 1; Synthesis of thermoplastic polyimide precursor)
To a glass flask having a volume of 2000 ml, 780 g of DMF and 107.5 g of BAPP were added, and 54.9 g of benzophenone tetracarboxylic dianhydride (hereinafter also referred to as BTDA) was gradually added while stirring in a nitrogen atmosphere. Subsequently, 34.6 g of TMEG was added and stirred for 30 minutes in an ice bath. A solution in which 3.0 g of TMEG was dissolved in 20 g of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to the viscosity and stirred. When the viscosity reached 3000 poise, addition and stirring were stopped to obtain a polyamic acid solution.

  The obtained polyamic acid solution was cast on a 25 μm PET film (Therapy HP, manufactured by Toyo Metallizing Co., Ltd.) so as to have a final thickness of 20 μm, and dried at 120 ° C. for 5 minutes. After peeling off the dried self-supporting film from PET, it is fixed to a metal pin frame and dried at 150 ° C. for 5 minutes, 200 ° C. for 5 minutes, 250 ° C. for 5 minutes, 350 ° C. for 5 minutes, A single layer sheet was obtained. The glass transition temperature of this thermoplastic polyimide was 190 ° C.

(Synthesis Example 2: Synthesis of thermoplastic polyimide precursor)
While adding 780 g of DMF and 115.6 g of 2,2-bis [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask having a capacity of 2000 ml, while stirring under a nitrogen atmosphere, 78.7 g of BPDA was gradually added. Subsequently, 3.8 g of TMEG was added and stirred for 30 minutes in an ice bath. A solution in which 2.0 g of TMEG was dissolved in 20 g of DMF was separately prepared, and this was gradually added to the reaction solution while being careful of the viscosity and stirred. When the viscosity reached 3000 poise, addition and stirring were stopped to obtain a polyamic acid solution.

  Moreover, operation similar to the synthesis example 1 was performed using the obtained polyamic-acid solution, the 20-micrometer-thick thermoplastic polyimide single layer sheet was measured, and it was 240 degreeC when the glass transition temperature was measured.

(Example 1)
The polyamic acid solution obtained in Synthesis Example 1 was applied on 18 μm rolled copper foil (BHY-22B-T, manufactured by Japan Energy Co., Ltd.) so that the final thickness was 4 μm, and dried at 140 ° C. for 1 minute. Then, the inside of the far-red furnace having an atmospheric temperature of 300 ° C. was passed through for 20 seconds with a tension of 30 N / m, and heated imidization was performed to obtain a copper foil with an adhesive layer.

  The obtained copper foil with an adhesive layer is arranged on both sides of a 17 μm-thick polyimide film (Apical HPP, Kaneka Chemical Industry Co., Ltd.) so that the thermoplastic polyimide layer is in contact with the polyimide film. (Apical 125 NPI; manufactured by Kaneka Chemical Co., Ltd.) and using a hot roll laminator, polyimide film tension 0.4 N / cm, copper foil tension with adhesive layer 15 N / cm, laminating temperature 330 ° C., laminating Thermal lamination was carried out continuously under the conditions of a pressure of 196 N / cm (20 kgf / cm) and a lamination speed of 1.5 m / min to produce a flexible metal-clad laminate according to the present invention.

(Example 2)
A flexible metal-clad laminate according to the present invention was produced by performing the same operation as in Example 1 except that 18 μm electrolytic copper foil (3EC-VLP, manufactured by Mitsui Kinzoku Co., Ltd.) was used as the copper foil.

(Example 3)
A flexible metal-clad laminate according to the present invention was carried out in the same manner as in Example 1 except that the polyamic acid solution obtained in Synthesis Example 2 was used, the atmospheric temperature of the IR furnace was set to 390 ° C., and the lamination temperature was set to 360 ° C. Was made.

(Comparative Example 1)
After diluting the polyamic acid solution obtained in Synthesis Example 1 with DMF to a solid content concentration of 10% by weight, a thermoplastic polyimide layer is formed on both sides of a 17 μm-thick polyimide film (Apical HPP, Kaneka Chemical Co., Ltd.). The polyamic acid was applied so that the final thickness of the (adhesion layer) was 4 μm, and then heated at 140 ° C. for 1 minute. Then, the inside of the far-infrared furnace having an atmospheric temperature of 300 ° C. was passed through a tension of 30 N / m for 20 seconds to perform heating imidization to obtain an adhesive film.

  An 18 μm rolled copper foil (BHY-22B-T; manufactured by Japan Energy) is disposed on both sides of the obtained adhesive film, and protective materials (Apical 125 NPI; manufactured by Kaneka Chemical Co., Ltd.) are disposed on both sides thereof. Continuous with tension of 0.4 N / cm, copper foil tension of 15 N / cm, laminating temperature of 330 ° C., laminating pressure of 196 N / cm (20 kgf / cm), laminating speed of 1.5 m / min. The laminate was heat laminated to produce a flexible metal-clad laminate.

(Comparative Example 2)
A flexible metal-clad laminate was prepared by performing the same operation as in Comparative Example 1 except that 18 μm electrolytic copper foil (3EC-VLP, manufactured by Mitsui Kinzoku Co., Ltd.) was used as the copper foil.

(Comparative Example 3)
Using the polyamic acid solution obtained in Synthesis Example 2, the same operation as in Comparative Example 1 was performed except that the atmospheric temperature of the IR furnace was set to 390 ° C. and the lamination temperature was set to 360 ° C., thereby producing a flexible metal-clad laminate.

  Table 1 shows the results of evaluation of the characteristics of the flexible metal-clad laminate used in each example and comparative example.

比較例１〜比較例３に示すように、ポリイミドフィルムに熱可塑性ポリイミド層を設けて銅箔とラミネートを行った場合は、エッチング後ならびに加熱後の寸法安定性に劣る結果となった。これに対し、銅箔に熱可塑性ポリイミド層を設けてポリイミドフィルムとラミネートを行った実施例１〜３では、張力の影響を受けにくくなり、良好な寸法安定性が確認された。また、製造方法を変えても、金属箔に対する接着強度には影響がなかった。

As shown in Comparative Examples 1 to 3, when a polyimide film was provided with a thermoplastic polyimide layer and laminated with a copper foil, the results were poor in dimensional stability after etching and after heating. On the other hand, in Examples 1 to 3 in which a thermoplastic polyimide layer was provided on a copper foil and laminated with a polyimide film, it was less affected by tension and good dimensional stability was confirmed. Moreover, even if the manufacturing method was changed, the adhesive strength to the metal foil was not affected.

Claims (5)

A method for producing a flexible metal-clad laminate in which a polyimide film and a metal foil are bonded via an adhesive layer containing a thermoplastic polyimide, and after an adhesive layer containing a thermoplastic polyimide is provided on one side of the metal foil A method for producing a flexible metal-clad laminate, characterized by being obtained by laminating with a polyimide film. The flexible metal according to claim 1, wherein when an adhesive layer is provided on one side of the metal foil, a solution containing polyamic acid, which is a precursor of thermoplastic polyimide, is cast and applied, and then imidized. A method for producing a tension laminate. 3. A flexible metal-clad laminate according to claim 1 or 2, which is obtained by bonding a metal foil with an adhesive layer and a polyimide film using a hot roll laminator having a pair of metal rolls. Method. A flexible metal-clad laminate obtained by the production method according to claim 3. The dimensional change rate before and after removing the metal foil, and the total value of the dimensional change rate before and after heating at 250 ° C. for 30 minutes after removing the metal foil is −0.08 to +0.08 in both the MD direction and the TD direction. The flexible metal-clad laminate according to claim 4, which is in a range.