JP2009066911A - Manufacturing method of flexible metal laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible metal laminate having no appearance defects such as crinkles. <P>SOLUTION: A manufacturing method of the flexible metal laminate comprises the step of laminating continuously a metal foil and a thermal adhesive film having a thermoplastic polyimide layer on at least one side of a non-thermoplastic polyimide layer with a heating-pressurizing device, and is characterized in that a protective material is placed between a material to be laminated and a pressurizing surface of the heating and pressurizing device, a heating and pressurizing are carried out, and the protective material is peeled at a higher temperature than a glass transition temperature (Tg) of the thermoplastic polyimide layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a flexible metal laminate. More specifically, the present invention relates to a method for producing a flexible metal laminate that is suitably used for electronic and electrical equipment.

  As a typical example of a laminated board used for an electronic / electrical equipment printed circuit board, there is a flexible printed circuit (hereinafter abbreviated as FPC).

  A copper-clad polyimide film (hereinafter abbreviated as CCL), which is a flexible metal laminate used for FPC, has three inexpensive layers composed of three materials: copper foil, polyimide base film, and epoxy thermosetting adhesive. There are two types: a type, a two-layer type that does not have an adhesive layer, and a three-layer type (hereinafter referred to as a pseudo two-layer) that has a polyimide adhesive of the same quality as the polyimide base film.

  The two-layer type and pseudo-two-layer type CCL are manufactured by directly plating copper on the polyimide film without using an adhesive (plating two-layer CCL), and applying polyamic acid to the copper foil, drying and imidization. A method of forming a polyimide layer without using a polyimide film (cast two-layer CCL), a method of laminating a polyimide film having a thermocompression-bondable polyimide layer on the surface with a copper foil (laminate two-layer CCL (pseudo-2) Layer type)) is known.

  Several methods have been proposed so far for producing a laminate two-layer CCL. For example, a method of bonding a polyimide adhesive in a sandwich between a polyimide film and a metal foil using a vacuum press or the like, and a method of continuously laminating using a hot roll laminator have been proposed. The latter method is advantageous in that a long product can be obtained.

As a method for preventing wrinkling during lamination, a protective material is placed between the pressure surface of the pressure heating molding device and the material to be laminated, pressure thermoforming is performed, and the protective material is peeled off from the laminate after cooling. Has been proposed (see, for example, Patent Documents 1 and 2). However, this method has a problem in that poor appearance occurs when the protective material is peeled off.
JP 2001-129918 A JP 2002-064259 A

  In view of the above problems, an object of the present invention is to provide a flexible metal laminate having no appearance defects such as wrinkles.

  That is, the present invention is a method for producing a flexible metal laminate in which a heat-fusible film having a thermoplastic polyimide layer on at least one surface of a non-thermoplastic polyimide layer and a metal foil are continuously bonded by a heating and pressing apparatus. A protective material is disposed between the pressure surface of the heating and pressurizing device and the material to be laminated, and heating and pressing are performed, and the protective material is peeled off at a temperature higher than the glass transition temperature of the thermoplastic polyimide layer. It is the manufacturing method of the flexible metal laminated board characterized.

  By the method for producing a flexible metal laminate of the present invention, a heat-resistant flexible metal laminate having a good appearance can be obtained even in the case of lamination at a high temperature that tends to cause appearance defects such as wrinkles. Therefore, the present invention provides a material suitable as a flexible metal laminate for electronic and electrical equipment.

  Details of the present invention will be described below.

  The flexible metal laminate in the present invention is obtained by bonding a heat-fusible film having a thermoplastic polyimide layer on at least one surface of a non-thermoplastic polyimide layer and a metal foil. A single-sided flexible metal laminate having a thermoplastic polyimide layer and a metal foil on one side of the non-thermoplastic polyimide layer, and a double-sided flexible metal laminate having a thermoplastic polyimide layer and a metal foil on both sides of the non-thermoplastic polyimide layer are included.

  Although it will not specifically limit as metal foil used for this invention if it can be used for the flexible metal laminated board for electronic electrical equipment, Generally, 3-50 micrometers thick rolled copper foil, electrolytic copper foil, etc. are mentioned. It is done. Further, the laminated surface of the metal foil and the opposite surface thereof may be subjected to rust prevention treatment, bumping treatment, easy adhesion treatment, or the like, if necessary. Further, the surface roughness Rz of the resist surface is preferably 1.0 to 2.0 μm, more preferably 1.0 to 1.5 μm.

  The heat-fusible film used in the present invention has a thermoplastic polyimide layer on at least one side of the non-thermoplastic polyimide layer, and may be provided on both sides. Here, non-thermoplastic refers to those having no glass transition temperature below the decomposition temperature of the resin, and thermoplastic refers to those having a glass transition temperature below the decomposition temperature of the resin.

  The thermoplastic polyimide layer preferably has a glass transition temperature (Tg) of 200 ° C. or higher, more preferably 230 ° C. or higher. If the Tg of the thermoplastic polyimide layer is 200 ° C. or higher, softening of the thermoplastic polyimide layer is suppressed by heating at the time of electronic component mounting, and the dimensional change rate is improved. The thermoplastic polyimide layer is composed of a polyimide-based adhesive composition such as a solvent-soluble polyimide composition or a silicone diamine-containing polyimide composition, or a hybrid composition in which an epoxy composition is mixed therewith. A layer can be exemplified. Furthermore, various additives may be blended in the thermoplastic polyimide layer in order to improve various properties. The thickness of the thermoplastic polyimide layer is preferably 1 to 6 μm because the adhesion to the metal foil and the dimensional change rate are good. The thickness of the non-thermoplastic polyimide layer is preferably 5 to 200 μm. Furthermore, the surface of the non-thermoplastic polyimide layer can be subjected to surface treatment such as hydrolysis, corona discharge, low temperature plasma, physical roughening, and easy adhesion coating treatment.

  The method for producing the heat-fusible film is not particularly limited, and examples thereof include a multilayer extrusion film-forming method in which several types of layers are formed at once, and a coating method in which other layers are sequentially formed on a non-thermoplastic polyimide film. As a coating method, various methods such as a gravure coater, a comma coater, a reverse coater, a bar coater, and a slit die coater can be used according to the physical properties of the coating material.

  In the method for producing a flexible metal laminate of the present invention, when a laminated material, that is, a heat-fusible film and a metal foil are continuously bonded together by a heating and pressing device, the pressure surface of the heating and pressing device and the laminated material Place protective material between them. If a protective material is not used, copper foil is burned and a flexible metal laminate with good appearance cannot be obtained.

  Hereinafter, FIG. 2 will be described as an example. FIG. 2 is a schematic view showing an example of a method for producing a flexible metal laminate of the present invention. The metal foil 1 is continuously heated and pressed by a pair of laminating rolls 5 through the protective material 3 on both surfaces of the heat-fusible film 2. Immediately after heating and pressing, the protective material 3 is peeled off and the product 4 is wound up. The protective material is preferably used at least on the metal foil side for the purpose of preventing oxidation of the copper foil and preventing depression of the metal roll. In the case of a single-sided flexible metal laminate, the protective material may be disposed between the pressure surfaces on both sides and the material to be laminated.

  In the present invention, it is important to peel off the protective material at a temperature higher than the Tg of the thermoplastic polyimide layer. That is, wrinkles due to peeling can be prevented by peeling the protective material in a state where the thermoplastic polyimide layer has fluidity at a temperature higher than Tg. When the protective material is peeled after the thermoplastic polyimide layer is cooled to Tg or less, the thermoplastic polyimide layer does not have fluidity, and wrinkles due to cooling unevenness when the protective material is peeled off are generated. Preferably it is Tg + 50 degreeC or more, More preferably, it is Tg + 100 degreeC or more.

  The protective material is preferably peeled off immediately after the material to be laminated is heated and pressed. Immediately refers to a range in which the temperature of the protective material does not decrease by 100 ° C. or more from the heating and pressing temperature. If it is immediately after heating and pressurization, it is not affected by temperature unevenness due to cooling, and wrinkles and unevenness due to peeling of the protective material can be further suppressed. Moreover, it is more preferable that the protective material is peeled off by bringing it into contact with a heating and pressing member that bonds the material to be laminated. Thereby, peeling of a protective material can be performed by a simple method immediately after heating and pressurization. Taking FIG. 2 as an example, the protective material 3 is preferably peeled off by a laminating roll 5 which is a heating and pressing member. Furthermore, in order to more stably peel the protective material, the peel angle of the protective material is preferably 45 ° or more, and more preferably 90 ° or more. Here, the peeling angle of the protective material refers to an angle corresponding to the circumference where the protective material contacts the peeling member, and refers to an angle indicated by θ in FIG. In addition, when manufacturing a single-sided flexible metal laminate, a protective material may be arranged between the pressure surfaces on both sides and the material to be laminated, and because the adhesion between the protective material and the metal foil, the protective material and the polyimide surface is different, The peeling angle can be adjusted to peel at a different angle.

  The protective material used in the present invention is required to withstand the processing temperature. For example, when heat-pressing at 250 ° C. or higher, a polyimide film, aramid film, metal foil, paper, etc. having higher heat resistance. Is effective. Moreover, a flexible metal laminated board can be manufactured more cheaply by repeatedly using a protective material. Therefore, the thickness of the protective material is preferably 25 μm or more, more preferably 50 μm or more so as to withstand repeated use.

  In the present invention, it is preferable to use a laminating apparatus having at least a pair of metal rolls as the heating and pressing apparatus. Furthermore, it is preferable to provide a winding shaft for each laminated material and protective material, a product, and a winding shaft for protective material. For example, a hot roll laminating machine, a double belt press machine, etc. are mentioned, Among these, a hot roll laminating machine having at least a pair of metal rolls is preferably used. The method for heating the metal roll is not particularly limited as long as it can be heated at a predetermined temperature, and examples thereof include a heat medium circulation method, a hot air heating method, and a dielectric heating method. The pressurization method is not particularly limited as long as a predetermined pressure can be applied, and includes a hydraulic method, a pneumatic method, a gap pressure method, and the like, and the pressure is not particularly limited. In addition, as devices that enable continuous lamination, tension control devices, line adjustment devices (EPC), etc., as well as cleaning equipment to maintain the quality as electronic circuit materials, adhesive rolls, static eliminators, A clean booth can be used as necessary.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Before describing the examples, a method for producing CCL and a method for evaluating characteristics will be described.

CCL fabrication method and characteristic evaluation method CCL Production Method 3,3 ′, 4,4′-bisphenyltetracarboxylic 0.4 mol in a reaction kettle equipped with a thermometer, dry nitrogen inlet, heating / cooling device with hot water / cooling water, and stirring device 3,3 ′, 4,4′-oxy-bisphenyltetracarboxylic anhydride 0.6 mol together with 2377 g of n-methylpyrrolidone and dissolved, and then 4,4′-oxy-bis-benzenediamine. 0 mol was added and reacted at 70 ° C. for 4 hours to obtain a polyamic acid solution. 200 g of toluene was added to the obtained polyamic acid solution, heated at 200 ° C., and an imidization reaction was performed for 3 hours while separating water azeotroped with toluene as the reaction progressed. Then, toluene was distilled off, the obtained polyimide varnish was poured into water, and the resulting precipitate was separated, ground, washed and dried to obtain a polyimide powder. 500 g of the obtained polyimide powder was added to 2834 g of dimethylacetamide and stirred at 40 ° C. for 2 hours to obtain a polyimide solution. In addition, Tg of the obtained polyimide was 240 degreeC.

  The obtained polyimide solution was coated on a commercially available “Kapton” (registered trademark) EN (manufactured by Toray DuPont Co., Ltd.) and then dried at 200 ° C. for 30 minutes to produce a heat-fusible film.

  Using the obtained heat-fusible film, the raw materials shown in the examples and comparative examples were placed, and a CCL was produced using a hot roll laminator. Here, the lamination conditions are as shown in each example and comparative example.

B. Peeling temperature measuring method The temperature of the protective material of a peeling part was measured using non-contact thermometer ST60XB (made by Raytek). In addition, it is estimated that the temperature of the protective material in a peeling part is equal to the temperature of the thermoplastic polyimide layer in a peeling part. The temperature measurement position in each Example and Comparative Example is shown in FIGS.

C. Appearance Evaluation Method The surface of the CCL was visually observed to evaluate the presence or absence of defects such as bubble entrapment, laminating wrinkles, horizontal rows, protective material peeling wrinkles, and discoloration due to oxidation of copper foil. Here, the peeling wrinkle of the protective material means a folding wrinkle that occurs when the protective material is peeled off, and is generated when the peeling state is unstable.

  In Tables 1 and 2, those without these defects are ◎, there is no practical problem, but only the edge part is partly peeled wrinkles ○, only the horizontal stage is △, practical problems The thing which a certain peeling wrinkle generate | occur | produced was described as x.

Examples 1-8
Using the copper foil, the protective material, and the lamination conditions shown in Table 1, the A.I. CCL was produced by the method described in 1. and the appearance was evaluated. The evaluation results are shown in Table 1. In addition, the copper foil and protective material which were used for each Example are as follows.
Electrolysis USLP-SE: Electrolytic copper foil (manufactured by Nippon Electrolytic Co., Ltd.)
Rolled BHY-22B-T: Rolled copper foil (Nikko Materials Co., Ltd.)
"Kapton" (registered trademark) 500H: Polyimide film (manufactured by Toray DuPont)
"Kapton" (registered trademark) 300H: Polyimide film (manufactured by Toray DuPont)
Comparative Examples 1-5
Using the copper foil, protective material, and laminate conditions shown in Table 2, CCL was produced by the method described in 1. and the appearance was evaluated. As a result, appearance defects such as peeling wrinkles and horizontal rows of the protective material were observed. The evaluation results are shown in Table 2.

Schematic showing an example of protective material peeling in the present invention Schematic which shows an example of the manufacturing method of the flexible metal laminated sheet of this invention. Schematic which shows another example of the manufacturing method of the flexible metal laminated sheet of this invention. Schematic which shows another example of the manufacturing method of the flexible metal laminated sheet of this invention. Schematic which shows an example of the manufacturing method of the conventional flexible metal laminated sheet Schematic which shows another example of the manufacturing method of the conventional flexible metal laminated sheet. Schematic which shows another example of the manufacturing method of the conventional flexible metal laminated sheet.

Explanation of symbols

1 Metal foil 2 Heat-sealable film 3 Protective material 4 Product 5 Laminate roll 6 Slow cooling roll 7 Slow cooling heater Peel angle A Peel temperature measurement position

Claims (4)

A method for producing a flexible metal laminate in which a heat-fusible film having a thermoplastic polyimide layer on at least one surface of a non-thermoplastic polyimide layer and a metal foil are continuously bonded by a heating and pressing apparatus, the heating heating A flexible metal characterized by disposing the protective material at a temperature higher than the glass transition temperature of the thermoplastic polyimide layer by disposing a protective material between the pressure surface of the pressure device and the material to be laminated and applying heat and pressure. A manufacturing method of a laminated board. 2. The method for producing a flexible metal laminate according to claim 1, wherein the protective material is peeled off immediately after the material to be laminated is heated and pressed. The method for producing a flexible metal laminate according to claim 1 or 2, wherein the protective material is peeled by bringing it into contact with a heat and pressure member to which the material to be laminated is bonded. The method for producing a flexible metal laminate according to claim 3, wherein the peeling angle of the protective material is 45 ° or more and 180 ° or less.

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