JP4774162B2 - Manufacturing method of heat-resistant flexible - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a laminated plate manufactured by a pressure heating molding apparatus. More specifically, the present invention relates to a method for manufacturing a heat-resistant flexible laminate used for electronic and electrical equipment.
[0002]
[Prior art]
In recent years, with the reduction in weight, size, and density of electronic and electrical equipment, there has been an increasing demand for flexible laminates in which a copper foil circuit is formed on a printed circuit board, particularly an insulating film. Generally, a flexible laminate is made by bonding a metal foil to an insulating film such as a polyimide film with a thermosetting adhesive in a heated state (epoxy resin, acrylic resin, etc.), and further curing the resin by raising the temperature. Metal is applied to a method of forming a circuit by etching a metal foil (a method of manufacturing a thermosetting laminate) or an insulating film (hereinafter referred to as an adhesive film in this specification) in which a heat-resistant thermoplastic adhesive layer is formed in advance. After the foils are bonded together in a heated state, the metal foil is etched to form a circuit (a method for producing a heat-fusing laminate).
[0003]
Various methods for producing a thermosetting laminate have been studied in the past. After pressing a resin-containing paper or a resin-impregnated glass cloth and a metal foil using a multi-stage press or a vacuum press, the temperature is increased for several hours. A method of obtaining a rigid laminate by thermally curing a resin by treatment, and laminating (lamination) a roll-shaped laminated material between a pair of heating rolls, and then thermally curing the resin by treatment for several hours at a high temperature. A method of obtaining a flexible laminate, a method of heat laminating using a double belt press device instead of a heating roll, and the like have been implemented.
[0004]
In the method for producing a thermosetting laminate, since the softening temperature of the thermosetting resin is relatively low, it is possible to laminate the metal foil on the insulating film at a temperature of about 100 ° C. Therefore, the thermal stress that the material to be laminated receives during lamination is relatively small, and there are few troubles associated with lamination such as generation of wrinkles.
[0005]
On the other hand, in the method for producing a heat-fusible laminate, it is necessary to heat-fuse the metal foil and the adhesive film at a temperature equal to or higher than the glass transition temperature (Tg) of a commonly used thermoplastic resin. Further, when used in electronic and electrical equipment, the flexible laminate is subjected to high-temperature heating in the process of component mounting of the electronic and electrical equipment, so it is necessary to provide an adhesive layer having a Tg of at least about 180 ° C. It is heat-sealed at a temperature of 200 ° C. or higher. In heat fusion at such a high temperature, the thermal expansion and thermal contraction of the material to be laminated are large, and the resulting laminated board is liable to cause appearance defects such as wrinkles.
[0006]
Furthermore, in the production of heat-fusing type laminates, if the tension of the adhesive film immediately before thermal lamination is low, if the metal material and the adhesive film are thermally laminated without overlapping until just before, the adhesive film is thermally laminated. As a result of thermal expansion at ambient temperature immediately before moving and moving in the width direction (TD direction) of the film, appearance defects such as minute wrinkles are likely to occur in the laminated laminate. JP-A-8-244168 describes a method in which a pair of heat rolls are used to laminate a thermoplastic polyimide film and a metal foil, and the thermoplastic polyimide film and the metal foil are directly laminated immediately before lamination. is doing. However, in this method, when the polyimide film is not in an absolutely dry state (when the film absorbs even a slight amount of moisture), moisture absorbed in the film evaporates due to the ambient temperature immediately before the thermal lamination. Since the evaporated water is covered with metal foil on both the film surface and the back surface, the escape route is lost, and the surface of the metal foil of the resulting laminate is uneven, resulting in poor appearance due to the evaporated water. There was a problem.
[0007]
[Problems to be solved by the invention]
The present invention solves the above-described conventional problems, and provides a method for producing a laminated board suitable as a material for obtaining a flexible substrate free from appearance defects such as wrinkles generated during thermal lamination.
[0008]
[Means for Solving the Problems]
The present inventors have found that an uneven pattern is not generated on the surface of a laminated board by drying the adhesive film in advance for the purpose of removing moisture in the adhesive film before laminating and heat laminating in that state, thereby completing the present invention. It came to do. The present inventors have further laminated the adhesive film and the metal foil before heat laminating, so that even when the feeding tension of the adhesive film is low, the adhesive film can be fed stably without meandering before the heat laminating. The present invention was completed by finding that fine wrinkles are not generated on the surface of the laminated plate after lamination.
[0009]
The present invention relates to a method for producing a heat-resistant flexible laminate comprising a metal foil and a heat-resistant adhesive film, which is excellent in appearance, the method comprising removing moisture from the heat-resistant adhesive film; metal foil and heat-resistant adhesive film And a step of disposing the protective material between at least one pair of metal rolls and heat-sealing; and a step of peeling the protective material from the obtained laminate.
[0010]
The present invention also relates to a method for producing a heat-resistant flexible laminate comprising a metal foil and a heat-resistant adhesive film, which is excellent in appearance, the method comprising removing moisture from the heat-resistant adhesive film; A step of arranging a protective material between at least one pair of metal rolls and heat-sealing the film to obtain a laminated body in which the protective material is adhered; a step of cooling the laminated body, and an obtained laminated body A step of peeling the protective material.
[0011]
Preferably, this method further includes a step of overlapping the metal foil and the heat-resistant adhesive film between the step of removing the moisture and the step of heat-sealing.
[0012]
The heat resistant adhesive film contains 50% by weight or more of a thermoplastic polyimide resin.
[0013]
The metal foil may be a copper foil having a thickness of 50 μm or less.
[0014]
The protective material may be a polyimide film.
[0015]
Preferably, the tension of the heat resistant adhesive film is 3 N / mm ² or less.
[0016]
Preferably, the heat sealing step is performed at a temperature of 200 ° C. or higher.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Details of the present invention will be described below.
[0018]
The laminate obtained by the production method of the present invention is mainly used as a flexible laminate for electronic electricity, but is not limited thereto.
[0019]
In the production method of the present invention, as the adhesive film, a single-layer film containing a resin having a heat-fusible property; a plurality of layers each having a resin layer having a heat-fusible property on both sides of a core layer having no heat-fusible property A film; and a sheet in which a base material such as paper or glass cloth is impregnated with a resin having heat-fusibility can be used. As an adhesive film for a flexible laminate, a flexible base material such as glass cloth is inferior in flexibility, so a single-layer film containing a resin having heat-fusibility, a core having no heat-fusibility A multilayer film provided with a resin layer having heat-fusibility on both sides of the layer is preferably used. As these single-layer film and multi-layer film, those having heat resistance are usually used, and the adhesive component having heat-fusibility is a thermoplastic polyimide-based component, for example, thermoplastic polyamideimide, thermoplastic polymer Ether imides, thermoplastic polyester imides and the like can be suitably used. An adhesive film containing 50% or more of these heat-resistant thermoplastic resins in the adhesive component is suitably used in the production method of the present invention. In addition to these heat-resistant thermoplastic resins, an adhesive film containing a thermosetting resin such as an epoxy resin or an acrylic resin can also be suitably used. Furthermore, if necessary, various additives known to those skilled in the art can also be added to the adhesive film in order to improve various properties.
[0020]
The structure of the adhesive film may be a single layer composed of only a heat-fusible adhesive component as long as it has a heat-resistant adhesive layer on the outer surface, but it has heat-fusibility from the viewpoint of dimensional characteristics. A film having a three-layer structure having a heat-fusible adhesive layer on both sides of the core layer not used is preferably used. A non-thermoplastic polyimide film is preferably used as the core layer having no heat-fusibility, but any film can be used without any particular limitation as long as it has heat resistance.
[0021]
The method for producing the adhesive film is also not particularly limited. When the adhesive layer is composed of a single adhesive layer, it can be formed by a belt casting method, an extrusion method, or the like. Further, when the adhesive film is composed of three layers of adhesive layer / core layer / heat-bonding layer having no heat-fusibility, both sides of the core layer (eg heat-resistant film) having no heat-fusibility are used. , A method of producing a three-layer adhesive film by applying an adhesive to each side or both sides simultaneously, and laminating and bonding a single-layer adhesive film consisting only of an adhesive component on both sides of a heat-resistant film It is produced by a method of forming a film.
[0022]
The method for producing a three-layer adhesive film by applying an adhesive is to apply a polyimide-based adhesive to a heat-resistant film in the state of polyamic acid, and then to dry, particularly when using a polyimide-based adhesive. A method of imidization, a method of directly applying a soluble polyimide resin to a heat-resistant film and drying, and a co-extrusion of each resin of the adhesive layer / core layer / adhesive layer not having heat-resistant fusing property, and heat resistance at a time There are methods for forming an adhesive film, but the method for forming the adhesive layer is not particularly limited.
[0023]
Although the metal foil used for the manufacturing method of this invention is not specifically limited, In the case of the laminated board used for an electronic electrical apparatus, a copper foil is used suitably from the point of electroconductivity and cost. Moreover, about the thickness of metal foil, since the line | wire width of a circuit pattern can be thinned, so that the thickness of copper foil is thin, copper foil of 50 micrometers or less is preferable. In particular, a copper foil having a thickness of 35 μm or less is less stiff than a copper foil having a thickness larger than that, and is likely to be wrinkled when thermally laminated. Therefore, the present invention exerts a remarkable effect on a copper foil having a thickness of 35 μm or less. As a kind of copper foil, rolled copper foil, electrolytic copper foil, HTE copper foil or the like can be used, and there is no particular limitation, and an adhesive may be applied to these surfaces.
[0024]
About a hot roll laminating apparatus, if it is an apparatus which heats a to-be-laminated material and applies a pressure and laminates, it can be used without a restriction | limiting in particular. The heating method is not particularly limited, and any heating method can be used as long as it can be heated at a predetermined temperature. As the heating method, for example, a heat medium circulation method, a hot air heating method, a dielectric heating method, or the like can be adopted. The heating temperature is preferably 200 ° C. or higher. However, when the laminate is used for passing through a solder reflow furnace having an atmospheric temperature of 240 ° C. for mounting electronic components, it has a Tg corresponding thereto. In order to use a heat-sealing film, it can usually be heated at 240 ° C. or higher. The material of the press roll of the hot roll laminating apparatus is not particularly limited, such as rubber and metal. However, when the laminating temperature reaches a high temperature of 280 ° C. or higher, the rubber roll cannot be used because it deteriorates, and a metal roll is preferably used. The pressurization method of the hot roll laminating apparatus is not particularly limited as long as a predetermined pressure can be applied. For example, a pressurization method such as a hydraulic method, a pneumatic method, or a gap pressure method is used. Can be. The pressure condition can be appropriately selected according to the purpose.
[0025]
As the protective material used in the present invention, any material that achieves the purpose of preventing appearance defects such as wrinkling of laminated products can be used. However, the material must be able to withstand the processing temperature. For example, when processing at 250 ° C., a polyimide film having higher heat resistance can be used effectively. The thickness of the protective material is not particularly limited, but a thickness of 50 μm or more is suitable for the purpose of suppressing wrinkle formation of the laminated board after lamination. If the thickness of the protective material is 75 μm or more, wrinkle formation can be suppressed almost completely, which is more preferable.
[0026]
Further, the protective material is not particularly required to be subjected to a treatment such as a surface treatment as long as it is lightly adhered to the material to be laminated. Conversely, if the protective material is not in close contact with the material to be laminated, a surface treatment that makes it lightly adhere to the protective material side, a similar surface treatment on the copper foil side, or both protective material and copper foil A surface treatment may be applied to the surface. In addition, surface treatments that allow the protective material and the material to be laminated to adhere lightly can also be used for surface treatments for other purposes, such as rust prevention treatments for the purpose of preventing oxidation of the copper foil surface. It is.
[0027]
When the thermoplastic resin is used as the material to be laminated, the temperature of the laminate when peeling the protective material is preferably a temperature equal to or lower than the Tg. More preferably, the peeling is performed at a temperature lower by 50 ° C. or more than Tg, and more preferably at a temperature lower by 100 ° C. or more than Tg. Most preferably, the protective material is peeled from the laminate when cooled to room temperature. As a method of cooling to room temperature, natural cooling may be used, but it is more effective to forcibly cool by a method such as applying cold air or holding it on a cooling roll.
[0028]
Although it does not prescribe | regulate especially as a method of drying an adhesive film, the following can be considered. After drying the original roll of adhesive film with a drier, set it on the feeding device of the hot roll laminator before the adhesive film absorbs moisture and heat laminate as it is, the state where the original roll of adhesive film is not dried Thus, a method may be considered in which the adhesive film is set in a feeding device of a hot roll laminating machine, the adhesive film is dried by a drying device before laminating, and then laminated. The drying device is not particularly limited as long as it is a device having a mechanism for drying the adhesive film. For example, a hot air circulation oven, an IR heater, an electrothermal heater, or the like can be used. Further, a method of drying the moisture by holding an adhesive film on a hot roll is also conceivable. The drying temperature may be any temperature at which moisture in the adhesive film evaporates, but if the temperature exceeds the decomposition temperature of the adhesive component of the adhesive film, it is not preferable because the adhesive strength decreases. The specific temperature range is preferably such that the surface temperature of the adhesive film is not lower than 100 ° C. and not higher than the decomposition temperature of the adhesive component. More preferably, it is Tg or less of the adhesive component.
[0029]
Also, generally, if the tension of the adhesive film is high before lamination, the adhesive film is difficult to meander and movement in the TD direction due to thermal expansion is also restricted. However, since the dimensional change rate of the laminate before and after the removal of the metal foil increases, it is not preferable to increase the feeding tension of the adhesive film too much. On the other hand, when the feeding tension of the adhesive film is 3 N / mm ² or less, wrinkles at the time of lamination that are considered to be caused by meandering of the adhesive film or elongation due to thermal expansion tend to occur. In order to prevent this, it is preferable to stack the adhesive film and the metal foil rather than transporting the metal foil and the adhesive film to the hot rolls by individual pass lines and laminating at once (FIG. 1d). 1) a), b) and c)).
[0030]
The mechanism for stacking the adhesive film and the metal material is not particularly limited as long as the adhesive film and the metal material are stacked before lamination. For example, a roll is disposed as shown in FIGS. It is conceivable that they are brought into close contact immediately before. The roll in the figure may be a metal roll or a rubber roll as long as it can transport the adhesive film and the metal foil, and is not particularly limited to a free roll or a drive roll.
[0031]
The following examples are provided to illustrate the invention in more detail.
[0032]
【Example】
The glass transition temperature (Tg) of the polyimide film described in the following examples is Shimadzu DSC CELL SCC-41 (differential scanning calorimeter), and the sample is heated at a rate of 10 ° C./min in a nitrogen stream. The measurement was performed at a temperature range from room temperature to 400 ° C.
[0033]
The rate of dimensional change was measured according to JIS C6471 (6.11 dimensional stability).
[0034]
In addition, NDP-3 made from Mitsui Metals was used for the electrolytic copper foil described in the following examples, and BHY-22B-T made from Japan Energy was used for the rolled copper foil.
[0035]
Example 1
An 18 μm electrolytic copper foil is placed on both sides of a 25 μm thermoplastic polyimide film (PIXEO TP-T manufactured by Kaneka Chemical Co., Ltd.) having a Tg of 190 ° C., and a 125 μm polyimide film (Kanebuchi Chemical Industry Co., Ltd.) as a protective film on both sides. (Apical 125AH manufactured by Co., Ltd.) is placed and laminated under the conditions of a temperature 350 ° C., L / S 2.0 m / min, and linear pressure 200 N / cm using a hot roll laminator with a pass line as shown in FIG. Then, the protective film and the laminated flexible laminate were cooled to room temperature in a lightly adhered state, and after cooling, the protective film was peeled from the flexible laminate to produce a flexible laminate.
[0036]
As a result, a flexible laminate having no defects such as wrinkles was obtained.
[0037]
In addition, the thermoplastic polyimide film was adjusted so that the film surface temperature might be 150 degreeC using the plate-shaped ceramic heater by Tokai High Heat Co., Ltd. before laminating.
[0038]
(Example 2)
A flexible laminate was produced in the same manner as in Example 1 except that an 18 μm rolled copper foil that was more likely to be wrinkled than the electrolytic copper foil used in Example 1 was disposed.
[0039]
As a result, a flexible laminate having no defects such as wrinkles was obtained.
[0040]
(Example 3)
The same 18 μm as Example 1 on both sides of a 25 μm thick adhesive film (PIXEO BP manufactured by Kaneka Chemical Co., Ltd.) having a thermoplastic polyimide resin component of Tg 190 ° C. on both surfaces of the non-thermoplastic polyimide film. In the same manner as in Example 1, a 125 μm polyimide film (Apical 125AH manufactured by Kaneka Chemical Industry Co., Ltd.) is disposed on both sides of the electrolytic copper foil as in Example 1. A flexible laminate was prepared.
[0041]
As a result, a flexible laminate having no defects such as wrinkles was obtained.
[0042]
Example 4
A flexible laminate was prepared in the same manner as in Example 3 except that 18 μm rolled copper foil was disposed on both sides of the three-layered adhesive film used in Example 3.
[0043]
As a result, a flexible laminate having no defects such as wrinkles was obtained.
[0044]
(Example 5)
A flexible laminate was produced in the same manner as in Example 4 except that lamination was performed by a pass line hot roll laminator as shown in FIG.
[0045]
As a result, a flexible laminate having no defects such as wrinkles was obtained.
[0046]
(Example 6)
A flexible laminate was produced in the same manner as in Example 4 except that lamination was performed by a hot roll laminator having a pass line as shown in FIG.
[0047]
As a result, a flexible laminate having no defects such as wrinkles was obtained.
[0048]
( Reference Example 7)
A flexible laminate was produced in the same manner as in Example 4 except that lamination was performed by a hot roll laminator with a pass line as shown in FIG.
[0049]
As a result, a flexible laminate having wrinkles even in the laminating direction was obtained.
[0050]
(Comparative Example 1)
A flexible laminate was obtained in the same manner as in Example 2 except that the laminate was carried out by a hot roll laminator with a pass line as shown in FIG.
[0051]
However, the process which dries a thermoplastic polyimide film with a plate-shaped ceramic heater before laminating was not performed.
[0052]
As a result, a foamed pattern due to volatile moisture of the adhesive film was generated on the surface of the flexible laminate, resulting in poor appearance.
[0053]
(Comparative Example 2)
A flexible laminate was obtained in the same manner as in Example 4 except that lamination was performed by a hot roll laminator with a pass line as shown in FIG.
[0054]
However, the process which dries a thermoplastic polyimide film with a plate-shaped ceramic heater before laminating was not performed.
[0055]
As a result, a foamed pattern due to volatile moisture of the adhesive film was generated on the surface of the flexible laminate, resulting in poor appearance.
[0056]
(Comparative Example 3)
The flexible laminate was obtained in the same manner as in Example 4 except that the feeding tension of the adhesive film was 5 N / mm ² and the laminate was laminated by a hot roll laminator with a pass line as shown in FIG. .
[0057]
However, the process which dries a thermoplastic polyimide film with a plate-shaped ceramic heater before laminating was not performed.
[0058]
As a result, a foamed pattern due to the volatile moisture of the adhesive film is generated on the surface of the flexible laminate, resulting in poor appearance, and the dimensional change rate is -0.24% in the MD direction (film traveling direction), TD direction (film width direction). ) + 0.25%.
[0059]
(Comparative Example 4)
A flexible laminate was obtained in the same manner as in Example 4 except that lamination was performed by a hot roll laminator with a pass line as shown in FIG.
[0060]
However, the process which dries a thermoplastic polyimide film with a plate-shaped ceramic heater before laminating was not performed.
[0061]
As a result, a foamed pattern due to volatile moisture of the adhesive film was generated on the surface of the flexible laminate, resulting in poor appearance.
[0062]
The results of Examples 1 to 7 and Comparative Examples 1 to 4 are summarized together with the material to be laminated, the adhesive film tension, the lamination conditions, the pass line used for the lamination, and the appearance and dimensional change rate of the obtained laminate. Table 1 shows. In Table 1, the laminating speed is the linear velocity of the peripheral edge of the metal roll, that is, the pressing surface of the metal roll when the laminated body is heat-sealed.
[0063]
[Table 1]
[0064]
As shown in Table 1, in Examples 1 to 7 where the heat-resistant adhesive film was dried, even when laminated with the heat-resistant adhesive film being in a low tension state, the uneven pattern was formed on the surface of the obtained laminate. At the same time, a fine wrinkle on the surface of the laminate was not observed in the laminate obtained by passing through a pass line for adhering the copper foil and the adhesive film immediately before lamination. Moreover, the dimensional change rate before and after the copper foil etching of the obtained laminate was small.
[0065]
【The invention's effect】
Provided is a method for obtaining a laminated board having no appearance defects such as wrinkles, which is suitable as a heat-resistant flexible laminated board for electronic and electrical equipment. According to the present invention, since a laminated board is obtained in a state where the feeding tension is low, a laminated board having excellent dimensional stability can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a pass line of a hot roll laminating machine.
FIG. 2 is a diagram showing an outline of a pass line of a hot roll laminating machine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Metal foil 2 Adhesive film 3 Protective film 4 Heat roll 5 Protective film winding device 6 Product winding device 7 Preheating device

Claims (7)

A method for producing a heat-resistant flexible laminate having an excellent appearance comprising a metal foil and a heat-resistant adhesive film:
A step of removing moisture from the heat-resistant adhesive film by drying the adhesive film with a drying device before laminating while feeding the adhesive film;
A step of heat-bonding the metal foil and the heat-resistant adhesive film between at least one pair of metal rolls and disposing a protective material between the metal foil and the metal roll; and the obtained laminate comprising the step, of separating the protective material from,
A method further comprising the step of stacking the metal foil and the heat-resistant adhesive film between the step of removing moisture and the step of heat-sealing . A method for producing a heat-resistant flexible laminate having an excellent appearance comprising a metal foil and a heat-resistant adhesive film:
A step of removing moisture from the heat-resistant adhesive film by drying the adhesive film with a drying device before laminating while feeding the adhesive film;
A laminate in which a metal foil and a heat-resistant adhesive film are disposed between at least one pair of metal rolls, and a protective material is disposed between the metal foil and the metal roll and heat-sealed so that the protective material adheres. Obtaining a body;
Cooling the laminate; and peeling the protective material from the resulting laminate ,
A method further comprising the step of stacking the metal foil and the heat-resistant adhesive film between the step of removing moisture and the step of heat-sealing . The heat-resistant adhesive film, contains a thermoplastic polyimide resin over 50 wt% A method according to any of claims 1 to 2. Wherein the metal foil is a less copper foil thickness 50 [mu] m, method according to any one of claims 1 to 2. It said protective material is a polyimide film, The method according to any one of claims 1 to 2. The tension of the heat-resistant adhesive film is 3N / mm ² or less, The method according to any one of claims 1 to 2. The heat-fusible to process is performed at 200 ° C. or higher, the method according to any one of claims 1 to 2.