TW202432684A - Method for manufacturing laminated and device for manufacturing the same - Google Patents

Abstract

The subject of the invention is to provide a method for manufacturing a laminate and a device for manufacturing the same, in which copper foils are laminated on both sides of a thermoplastic polymer film, and the foaming in the inner of the thermoplastic polymer film and at the interface with the copper foil is prevented. The method for manufacturing a laminate is carried out continuously by using roll-to-roll processing, which comprises: Step (1) of thermos-compressing a polymer film and a first copper foil at a temperature at which the polymer film softens under a state that a first copper foil 11a overlaid on the surface of a thermoplastic polymer film 10; Step (2) of heating the thermoplastic polymer film at a temperature near its melting point; Step (3) of heating the thermoplastic polymer film and the second copper foil at a temperature at which the polymer film softens under a state that a second copper foil 11b is laminated on the back side of the thermoplastic polymer film; Step (4) of heating the thermoplastic polymer film at a temperature near its melting point.

Description

Method and device for manufacturing laminated body

The present invention relates to a method for manufacturing a laminate having copper foils laminated on two surfaces of a thermoplastic polymer film and a manufacturing device thereof.

Flexible wiring boards are mostly made of a laminate made of a thermoplastic polymer film and copper foil. The circuit pattern is formed by etching the copper foil of the laminate.

As a method for manufacturing a laminated body in which copper foil is laminated on both sides of a thermoplastic polymer film, for example, Patent Document 1 discloses the following method: a laminated body is formed by overlapping copper foil on both sides of a thermoplastic polymer film and heat-pressing the laminated body using a pair of heating and pressurizing rollers. This method can heat-press the copper foil on both sides of a thermoplastic polymer film at the same time by a roll-to-roll method, so that a laminated body in which copper foil is laminated on both sides of a thermoplastic polymer film can be manufactured with good productivity. [Prior technical document] [Patent document] Patent document 1: Japanese Patent Publication No. 2014-128913

[Invention Summary] [Technical Problems to be Solved by the Invention]

In a flexible wiring board in which a circuit pattern is formed by etching copper foil laminated on both surfaces of a thermoplastic polymer film, the thermoplastic polymer film is being required to be thinner as the density of the circuit pattern increases and the frequency of the transmission signal increases.

When the copper foil is heat-pressed onto the two surfaces of the thermoplastic polymer film using a pair of heating and pressure rollers, the thermoplastic polymer film is heated to a temperature close to the melting point in order to enhance the bonding strength between the thermoplastic polymer film and the copper foil.

When a thermoplastic polymer film is heated to a temperature close to the melting point, gas is released from the thermoplastic polymer film. When a pair of heating and pressurizing rollers are used to heat-press the copper foil on both sides of the thermoplastic polymer film at a temperature close to the melting point of the thermoplastic polymer film, the copper foils stacked on both sides of the thermoplastic polymer film are subjected to pressure from the pair of heating and pressurizing rollers. At this time, since the two sides of the thermoplastic polymer film are in a state of being sandwiched by the copper foil, the gas released from the thermoplastic polymer film has no escape route. When the pressure from the pair of heating and pressurizing rollers is released, the released gas will foam inside the thermoplastic polymer film or at the interface with the copper foil. As a result, there arises problems such as poor insulation of the thermoplastic polymer film and reduced bonding strength between the thermoplastic polymer film and the copper foil.

In particular, when the thermoplastic polymer film is thinned (for example, with a thickness of less than 100 μm), even if only microscopic bubbles of several tens of μm are generated, poor insulation of the thermoplastic polymer film and a decrease in bonding strength will become significant.

In order to prevent blistering caused by heat pressing at a temperature close to the melting point, the following method can be thought of: first, copper foil is overlapped on one side of a thermoplastic polymer film and heat pressed at a temperature close to the melting point, and then the copper foil is overlapped on the other side of the thermoplastic polymer film and heat pressed at a temperature close to the melting point, thereby manufacturing a laminate with copper foil laminated on both sides of the thermoplastic polymer film.

However, in this method, when heat pressing is performed at a temperature close to the melting point of the thermoplastic polymer film, there is a problem that the surface of the thermoplastic polymer film on the side not overlapping the copper foil adheres to the roll and cannot be peeled off.

To solve this problem, a mold release film can be provided on the surface of the thermoplastic polymer film on the side not overlapped with the copper foil. However, in this case, both sides of the thermoplastic polymer film are covered with the copper foil and the mold release film. Therefore, as in the case where the copper foil is heat-pressed onto both sides of the thermoplastic polymer film at the same time, the gas released from the thermoplastic polymer film will foam inside the thermoplastic polymer film or at the interface with the copper foil.

The present invention was completed in view of the above-mentioned problem, and its purpose is to prevent the foaming caused by the released gas from the thermoplastic polymer film inside the thermoplastic polymer film or at the interface with the copper foil while maintaining the bonding strength between the thermoplastic polymer film and the copper foil in a manufacturing method and manufacturing device for manufacturing a laminated body with copper foil laminated on both surfaces of the thermoplastic polymer film using a pair of heating and pressure rollers. 〔Technical means for solving the technical problem〕-

The manufacturing method of the laminated body related to the present invention is a manufacturing method of the laminated body made by laminating copper foil on two surfaces of a thermoplastic polymer film, comprising process (A), process (B), process (C), and process (D); in the aforementioned process (A), a pair of heating and pressurizing rollers are introduced into the state where the first copper foil has been overlapped on the surface of the thermoplastic polymer film, and the thermoplastic polymer film and the first copper foil are heat-pressed at a temperature at which the thermoplastic polymer film softens; in the aforementioned process (B), after the aforementioned process (A), the back side of the thermoplastic polymer film where the first copper foil has not been laminated is opened, and the thermoplastic polymer film is heated at a temperature close to the melting point of the thermoplastic polymer film. The thermoplastic polymer film is heated; in the aforementioned process (C), after the aforementioned process (B), a pair of heating and pressing rollers are introduced in a state where the second copper foil is overlapped on the back side of the thermoplastic polymer film, and the thermoplastic polymer film and the second copper foil are heat-pressed at a temperature at which the thermoplastic polymer film softens; in the aforementioned process (D), after the aforementioned process (C), the thermoplastic polymer film is heated at a temperature close to the melting point of the aforementioned thermoplastic polymer film in a state where the first copper foil and the second copper foil are stacked on both sides of the thermoplastic polymer film; the aforementioned process (A), the aforementioned process (B), the aforementioned process (C) and the aforementioned process (D) are continuously performed in a roll-to-roll manner.

The manufacturing device of the laminated body related to the present invention is a manufacturing device of the laminated body which is manufactured by laminating copper foil on two surfaces of a thermoplastic polymer film in a roll-to-roll manner. The aforementioned manufacturing device of the laminated body comprises a first unwinding shaft, a second unwinding shaft, a third unwinding shaft, a pair of first heating and pressurizing rollers, a first heating device, a pair of second heating and pressurizing rollers, a second heating device and a winding shaft; the aforementioned first unwinding shaft supplies the aforementioned thermoplastic polymer film; the aforementioned third .... The second roll-out roll supplies the first copper foil; the third roll-out roll supplies the second copper foil; the first pair of first heating and pressurizing rollers heat-press the thermoplastic polymer film and the first copper foil at a temperature at which the thermoplastic polymer film softens, while the first copper foil supplied by the second roll-out roll is overlapped on the surface of the thermoplastic polymer film supplied by the first roll-out roll; the first heating device heats the thermoplastic polymer film at a temperature close to the melting point of the thermoplastic polymer film. The thermoplastic polymer film on which the first copper foil is laminated is heated by a pair of first heating and pressurizing rollers, and the back side of the thermoplastic polymer film on which the first copper foil is not laminated is open; the pair of second heating and pressurizing rollers overlap the second copper foil supplied by the third unwinding roller on the back side of the thermoplastic polymer film heated by the first heating device, and heat the thermoplastic polymer film and the first copper foil at a temperature at which the thermoplastic polymer film softens. The first copper foil and the second copper foil are heat-pressed; the second heating device heats the thermoplastic polymer film laminated with the second copper foil by a pair of second heating and pressing rollers at a temperature close to the melting point of the thermoplastic polymer film, in a state where the first copper foil and the second copper foil are laminated on the two surfaces of the thermoplastic polymer film; the winding shaft winds up the laminated body with the copper foil laminated on the two surfaces of the thermoplastic polymer film heated by the second heating device. [Effect of the invention]

According to the present invention, in a manufacturing method and a manufacturing apparatus for manufacturing a laminate having copper foils laminated on both surfaces of a thermoplastic polymer film using a pair of heating and pressure rollers, it is possible to prevent bubbling caused by released gas from the thermoplastic polymer film inside the thermoplastic polymer film or at the interface with the copper foil while maintaining the bonding strength between the thermoplastic polymer film and the copper foil.

The following is a detailed description of the embodiments of the present invention with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments. Appropriate changes can be made within the scope of achieving the effects of the present invention.

FIG1 is a flow chart showing each process of a method for manufacturing a laminate in one embodiment of the present invention. FIG2 is a diagram schematically showing a manufacturing apparatus for a laminate in one embodiment of the present invention. The laminate in this embodiment has a structure in which copper foil is laminated on both sides of a thermoplastic polymer film, and is manufactured in a roll-to-roll manner using the manufacturing apparatus shown in FIG2.

As the material of the thermoplastic polymer film, liquid crystal polymer, polyphenylene sulfide, cycloolefin, polystyrene, polyamide, polyamide imide, polyether imide, polyether ketone, polysulfone, polyethersulfone, polyarylate, polytetrafluoroethylene, polyvinylidene fluoride, perfluoroalkoxyalkane, perfluoroethylene propylene copolymer, ethylene-tetrafluoroethylene copolymer, etc. can be used. In particular, as the thermoplastic polymer film, a liquid crystal polymer film with small dielectric loss and dielectric loss tangent is preferred. The thickness of the thermoplastic polymer film is preferably 10 to 200 μm, more preferably 25 to 75 μm.

As shown in FIG1 , the surface of the thermoplastic polymer film is subjected to plasma treatment (Plasma Treatment) (step S1). Specifically, as shown in FIG2 , the surface of the thermoplastic polymer film 10 supplied from the first unwinding shaft 20 is subjected to plasma treatment using a plasma treatment device 30a. The gas used in the plasma treatment can be, for example, argon, nitrogen, etc.

For example, plasma treatment can be performed by atmospheric pressure plasma. By plasma treatment, functional groups are imparted to the surface of the thermoplastic polymer film 10, so that when the copper foil is hot-pressed on the thermoplastic polymer film 10, chemical bonding between the thermoplastic polymer film 10 and the copper foil can be obtained, and the bonding strength between the thermoplastic polymer film 10 and the copper foil can be improved. It should be noted that the plasma treatment is performed to improve the bonding strength between the thermoplastic polymer film 10 and the copper foil, and it is not necessary to perform the treatment. For the same purpose, a silane coupling agent can also be imparted to the surface of the copper foil.

Next, as shown in FIG1 , in a state where the first copper foil 11a is overlapped on the surface of the thermoplastic polymer film 10 (first copper foil/polymer film), the thermoplastic polymer film 10 and the first copper foil 11a are heat-pressed at a temperature at which the thermoplastic polymer film 10 softens (step S2). At this time, the pair of heating and pressing rollers 22 or 24 do not necessarily need to be set to the same temperature, but in the case of different temperatures, the higher temperature is set as the heat-pressing temperature.

Specifically, as shown in FIG. 2 , in a state where the first copper foil 11 a supplied by the second unwinding reel 21 is overlapped on the surface of the thermoplastic polymer film 10 supplied by the first unwinding reel 20, a pair of first heating and pressing rollers 22 are introduced using a guide roller 50 to perform heat pressing on the thermoplastic polymer film 10 and the first copper foil 11 a.

During the heat pressing, the softened thermoplastic polymer film 10 will enter the fine concave-convex surfaces of the first copper foil 11a and solidify, thereby exhibiting an anchoring effect, and the thermoplastic polymer film and the copper foil are thus temporarily bonded together.

When the surface of the thermoplastic polymer film 10 has been plasma treated, in addition to the mechanical bonding caused by the anchoring effect, the thermoplastic polymer film 10 and the copper foil can also be chemically bonded, so the bonding strength between the thermoplastic polymer film 10 and the copper foil is further improved.

The temperature for heat pressing the thermoplastic polymer film 10 and the first copper foil 11a is preferably above the softening temperature of the thermoplastic polymer film and below a temperature 20°C higher than the softening temperature of the thermoplastic polymer film. If the heat pressing temperature is lower than the softening temperature of the thermoplastic polymer film, air will enter the interface between the thermoplastic polymer film 10 and the first copper foil 11a, and the anchoring effect cannot be fully exerted, and the temporary bonding of the thermoplastic polymer film 10 and the copper foil 11a cannot be fully obtained, which is not good. If the heat pressing temperature exceeds the softening temperature of the thermoplastic polymer film by 20°C, the surface of the thermoplastic polymer film 10 that has not overlapped the first copper foil 11a will adhere to the heat pressing roller 22 and cannot be peeled off, which is not good.

The softening temperature of thermoplastic polymer films can be measured by the dynamic mechanical analysis (DMA) method according to JIS K7244-4: 1999, from the peak temperature of the loss tangent (tanδ = loss modulus / storage modulus). Specifically, a dynamic mechanical analysis device ("DVE-V4FT Rheospectoler" manufactured by Rheology) is used to measure the storage modulus (E'), loss modulus (E'') and loss tangent (tanδ) by heating the material from low temperature to high temperature in the tensile mode (frequency: 11 Hz) at a heating rate of 3°C/min. The softening temperature can be measured from the peak temperature of the loss tangent.

In the present embodiment, since the thermoplastic polymer film 10 and the first copper foil 11a are heat-compressed at a softening temperature lower than the melting point of the thermoplastic polymer film 10, no gas is released from the thermoplastic polymer film 10 during the heat-compressing process. Therefore, during the heat-compressing process, no bubbles are generated inside the thermoplastic polymer film or at the interface with the copper foil due to the released gas from the thermoplastic polymer film.

Next, as shown in FIG. 1 , the back side of the thermoplastic polymer film 10 on which the first copper foil 11a has not yet been laminated is opened (first copper foil/polymer film), and the thermoplastic polymer film 10 is heated at a temperature close to the melting point of the thermoplastic polymer film 10 (step S3 ).

Specifically, as shown in FIG. 2 , the thermoplastic polymer film 10 on which the first copper foil 11 a is laminated by a pair of first heating and pressurizing rollers 22 is guided to the vicinity of the first heating device 40 a by guide rollers 51 and 52 to heat the thermoplastic polymer film 10 .

The thermoplastic polymer film 10, which has been liquefied near the melting point, shows "wetness" at the interface with the first copper foil 11a. The liquefied thermoplastic polymer film 10 thus enters the fine concave-convex surface of the first copper foil 11a without gaps and solidifies, which can obtain a better anchoring effect. As a result, the thermoplastic polymer film 10 and the first copper foil 11a can be firmly bonded without using a pair of heating and pressure rollers to heat-press the thermoplastic polymer film 10 and the first copper foil 11a.

It should be noted that when a liquid crystal polymer film is used as the thermoplastic polymer film 10, since the molecular orientation of the liquid crystal polymer film becomes random near the melting point, the strength in the thickness direction increases, and the bonding strength between the liquid crystal polymer film and the first copper foil can be further improved.

Here, the temperature at which the thermoplastic polymer film 10 is heated is preferably at least 20°C lower than the melting point of the thermoplastic polymer film 10 and at most 50°C higher than the melting point of the thermoplastic polymer film 10. If the heating temperature is lower than 20°C lower than the melting point of the thermoplastic polymer film 10, the bonding strength between the thermoplastic polymer film 10 and the first copper foil 11a cannot be obtained, which is not good. If the heating temperature is higher than 50°C higher than the melting point of the thermoplastic polymer film 10, the thermal decomposition of the thermoplastic polymer film 10 will proceed excessively, and the bonding strength will decrease, which is not good.

The melting point of the thermoplastic polymer film 10 can be measured by differential scanning calorimetry (DSC). Specifically, about 10 mg of a sample is heated from room temperature to a temperature above the expected melting point at a heating rate of 10°C/min under the conditions of nitrogen (30 mL/min) and a heating rate of 10°C/min using a differential scanning calorimeter (DSC7200 manufactured by Hitachi High-Technologies Corporation). The melting point can be determined from the peak top temperature of the endothermic peak observed when the sample is melted.

In this embodiment, when the thermoplastic polymer film 10 is heated near the melting point, the back side of the thermoplastic polymer film 10 on which the first copper foil 11a is not yet laminated is in an open state. Therefore, during the heating process near the melting point, the gas released from the thermoplastic polymer film can be released to the outside from the back side of the thermoplastic polymer film 10. As a result, the formation of bubbles inside the thermoplastic polymer film 10 or at the interface with the first copper foil 11a can be prevented.

The first heating device 40a can be, for example, an electromagnetic induction heating device. The electromagnetic induction heating device is a device that arranges a plurality of induction heating coils near the thermoplastic polymer film 10 and directly heats the first copper foil 11a by electromagnetic induction by passing current through the induction heating coils. In this way, the thermoplastic polymer film 10 bonded with the first copper foil 11a can be heated by heat conduction from the first copper foil 11a.

It should be noted that the first copper foil 11a is a non-magnetic material, but if the thickness of the copper foil is less than about 100 μm, resistance loss will occur. Therefore, by properly adjusting the frequency of electromagnetic induction and the positional relationship between the first copper foil 11a and the induction heating coil, the first copper foil 11a can be heated by the Joule heat generated by the eddy current induced inside the copper foil. If the thickness of the copper foil is less than 20 μm, it is easy to heat the copper foil, but if it is less than 1 μm, the heat generation will be insufficient, and it is difficult to fully heat the thermoplastic polymer film 10, so it is not good.

As shown in Fig. 2, the temperature of the heated thermoplastic polymer film 10 can be measured by detecting the minute irreversible change of the surface reflection spectrum caused by the heating process of the thermoplastic polymer film 10 or the first copper foil 11a using a hyperspectral camera 41a arranged near the thermoplastic polymer film 10. Since the electromagnetic induction heating has excellent responsiveness, the temperature at which the thermoplastic polymer film 10 is heated can be quickly controlled by feeding back the temperature measured by the hyperspectral camera 41a to the electromagnetic induction heating device.

The first heating device 40a may be a resistance heating device, a heating lamp device, or the like, in addition to an electromagnetic induction heating device.

Next, as shown in FIG1 , the back side of the thermoplastic polymer film 10 is subjected to plasma treatment (step S4). Specifically, as shown in FIG2 , the thermoplastic polymer film 10 heated by the first heating device 40 a is guided to the vicinity of the plasma treatment device 30 b by the guide roller 53, and the back side of the thermoplastic polymer film 10 is subjected to plasma treatment by the plasma treatment device 30 b.

This plasma treatment has the same purpose as the plasma treatment of the surface of the thermoplastic polymer film 10 already performed in step S2, so the description thereof is omitted.

Next, as shown in FIG. 1 , in a state where the second copper foil 11 b is overlapped on the back side of the thermoplastic polymer film 10 (first copper foil/polymer film/second copper foil), the thermoplastic polymer film 10 and the second copper foil 11 b are heat-pressed at a temperature at which the thermoplastic polymer film 10 softens (step S5).

Specifically, as shown in FIG. 2 , in a state where the second copper foil 11 b supplied by the third unwinding shaft 23 is overlapped on the back side of the thermoplastic polymer film 10 that has been plasma-treated by the plasma processing device 30 b, a pair of second heating and pressurizing rollers 24 are introduced using guide rollers 54 to thermally pressurize the thermoplastic polymer film 10 and the second copper foil 11 b.

During the heat pressing, the softened thermoplastic polymer film 10 will enter the fine concave-convex surfaces of the second copper foil 11b and solidify, thereby exhibiting an anchoring effect, and the thermoplastic polymer film 10 and the second copper foil 11b are thus temporarily bonded together.

Here, the temperature for heat pressing the thermoplastic polymer film 10 and the second copper foil 11b is preferably above the softening temperature of the thermoplastic polymer film 10 and below a temperature 20°C higher than the softening temperature of the thermoplastic polymer film 10. If the heat pressing temperature is lower than the softening temperature of the thermoplastic polymer film, air will enter the interface between the thermoplastic polymer film 10 and the second copper foil 11b, and the anchoring effect cannot be fully exerted, and the temporary bonding of the thermoplastic polymer film 10 and the second copper foil 11b cannot be fully obtained, which is not good.

The temperature in the heat pressing process of step S2 is not necessarily the same as the temperature in the heat pressing process of step S5. For example, when the thermoplastic polymer film 10 is heated to a temperature close to the melting point, the softening temperature rises. The heat pressing process of step S5 is performed after the heating process of step S3 to a temperature close to the melting point. Therefore, the softening temperature of the thermoplastic polymer film 10 in the heat pressing process of step S5 refers to the softening temperature of the thermoplastic polymer film 10 after the heating process of step S3. In the case where the softening temperature of the thermoplastic polymer film 10 has been increased in the heating process of step S3, the temperature in the heat pressing process of step S5 may be set higher than the temperature in the heat pressing process of step S2.

Next, as shown in FIG. 1 , in a state where the first copper foil 11 a and the second copper foil 11 b are already layered on both surfaces of the thermoplastic polymer film 10 (first copper foil/polymer film/second copper foil), the thermoplastic polymer film 10 is heated at a temperature close to the melting point of the thermoplastic polymer film 10 (step S6).

Specifically, as shown in FIG. 2 , the thermoplastic polymer film 10 on which the first copper foil 11a and the second copper foil 11b are respectively laminated on both sides by a pair of second heating and pressurizing rollers 24 is guided to the vicinity of the second heating device 40b to heat the thermoplastic polymer film 10.

The second heating device 40b can be, for example, an electromagnetic induction heating device. As shown in FIG2 , the temperature of the heated thermoplastic polymer film 10 can be measured using a hyperspectral camera 41b disposed near the thermoplastic polymer film 10. In addition to the electromagnetic induction heating device, the second heating device 40b can also be a resistance heating device, a heating lamp device, etc.

The thermoplastic polymer film 10, which has been liquefied near the melting point, shows "wetness" at the interface with the second copper foil 11b. The liquefied thermoplastic polymer film 10 thus enters the fine concave-convex surface of the second copper foil 11b without gaps and solidifies, which can obtain a better anchoring effect. As a result, the thermoplastic polymer film 10 and the second copper foil 11b are firmly bonded together.

Here, the temperature at which the thermoplastic polymer film 10 is heated is preferably at least 20°C lower than the melting point of the thermoplastic polymer film 10 and at most 50°C higher than the melting point of the thermoplastic polymer film 10. If the heating temperature is lower than 20°C lower than the melting point of the thermoplastic polymer film 10, the bonding strength between the thermoplastic polymer film 10 and the first copper foil 11a cannot be obtained, which is not good. If the heating temperature is higher than 50°C higher than the melting point of the thermoplastic polymer film 10, the thermal decomposition of the thermoplastic polymer film 10 will proceed excessively, and the bonding strength will decrease, which is not good.

In this embodiment, when the thermoplastic polymer film 10 is heated at a temperature close to the melting point, even if the first copper foil 11a and the second copper foil 11b are laminated on both surfaces of the thermoplastic polymer film 10, since the thermoplastic polymer film 10 has been heated at a temperature close to the melting point in step S3, gas will not be released again from the thermoplastic polymer film 10. Therefore, bubbles caused by the release of gas from the thermoplastic polymer film 10 will not be generated inside the thermoplastic polymer film 10 or at the interface with the first copper foil 11a and the second copper foil 11b.

The temperature in the heating process of step S3 and the temperature in the heating process of step S6 are not necessarily the same temperature. For example, when the thermoplastic polymer film 10 is heated to a temperature close to the melting point, the melting point may rise. The heating process of step S6 is performed after the heating process of step S3. Therefore, the melting point of the thermoplastic polymer film 10 in the heating process of step S6 refers to the melting point of the thermoplastic polymer film 10 after the heating process of step S3. In the case where the melting point of the thermoplastic polymer film 10 has risen in the heating process of step S3, the temperature in the heating process of step S6 can be set to be higher than the temperature in the heating process of step S3.

Alternatively, the temperature in the heating process of step S6 may be set lower than the temperature in the heating process of step S3. If gas still remains in the thermoplastic polymer film 10 after the heating process of step S3, the release of the residual gas can be suppressed by setting the heating temperature of step S6 lower than the heating temperature of step S3.

Finally, as shown in FIG. 2 , by winding up the thermoplastic polymer film 10 heated by the second heating device 40 b using the winding shaft 25 , a laminate having the first copper foil 11 a and the second copper foil 11 b laminated on both surfaces of the thermoplastic polymer film 10 is obtained.

As described above, according to the present embodiment, while the bonding strength between the thermoplastic polymer film 10 and the first copper foil 11a and the second copper foil 11b is maintained, bubbles are not generated inside the thermoplastic polymer film 10 or at the interface between the first copper foil 11a and the second copper foil 11b due to the released gas from the thermoplastic polymer film 10. In this way, a laminate in which the first copper foil 11a and the second copper foil 11b are laminated on both surfaces of the thermoplastic polymer film 10 can be manufactured.

By continuously performing the processes of heat-pressing the first copper foil 11a on one side of the thermoplastic polymer film 10 in a roll-to-roll manner, heating the thermoplastic polymer film 10 on which the first copper foil 11a is already laminated on one side, heat-pressing the second copper foil 11b on the other side of the thermoplastic polymer film 10, and heating the thermoplastic polymer film 10 on which the first copper foil 11a and the second copper foil 11b are already laminated on both sides, a laminate having the first copper foil 11a and the second copper foil 11b laminated on both sides of the thermoplastic polymer film 10 can be manufactured with good productivity.

As shown in FIG2 , the manufacturing apparatus of the laminate in the present embodiment includes a first unwinding shaft 20 for supplying a thermoplastic polymer film 10, a second unwinding shaft 21 for supplying a first copper foil 11 a, a third unwinding shaft 23 for supplying a second copper foil 11 b, a winding shaft 25 for winding the laminate, a pair of first heating and pressurizing rollers 22, a pair of second heating and pressurizing rollers 24, a first heating device 40 a, and a second heating device 40 b.

A pair of second heating and pressurizing rollers 24 heat-compresses the thermoplastic polymer film 10 and the first copper foil 11a at a temperature at which the thermoplastic polymer film 10 softens, while the first copper foil 11a supplied from the second unwinding reel 21 is overlapped on the surface of the thermoplastic polymer film 10 supplied from the first unwinding reel 20.

The first heating device 40a heats the thermoplastic polymer film 10 laminated with the first copper foil 11a by a pair of first heating and pressure rollers 22 at a temperature close to the melting point of the thermoplastic polymer film 10. At this time, the back side of the thermoplastic polymer film 10 not laminated with the first copper foil 11a is open.

A pair of second heating and pressing rollers 24 heat-press the thermoplastic polymer film 10 and the second copper foil 11b at a temperature at which the thermoplastic polymer film 10 softens, while overlapping the second copper foil 11b supplied by the third unwinding shaft 23 on the back side of the thermoplastic polymer film 10 heated by the first heating device 40a.

The second heating device 40b heats the thermoplastic polymer film 10, which has been laminated with the second copper foil 11b by a pair of second heating and pressure rollers 24, at a temperature close to the melting point of the thermoplastic polymer film 10 when the first copper foil 11a and the second copper foil 11b are laminated on both surfaces of the thermoplastic polymer film 10.

The winding shaft 25 rolls up the laminated body in which the first copper foil 11a and the second copper foil 11b are laminated on both surfaces of the thermoplastic polymer film 10 which has been heated by the second heating device 40b. [Example]

The present invention is described in more detail with reference to the following embodiments, but the present invention is not limited to these embodiments.

In the embodiments and comparative examples, the following liquid crystal polymer films and copper foils were used.

Liquid crystal polymer film: Made by CHIYODA INTEGRE, trade name "PELLICULE" (thickness: 50μm, width: 130mm, softening temperature: 170℃, melting point: 280℃)

Copper foil: manufactured by JX Metal Corporation, electrolytic copper foil, model "JXEFL-V2" (thickness: 12μm, width: 270mm)

The laminate was produced using the roll-to-roll manufacturing apparatus shown in Fig. 2. The processing speed was 1 m/min, the tension for drawing out the liquid crystal polymer film 10 was 100 N/m, the tension for drawing out the first and second copper foils 11a and 11b was 100 N/m, and the winding tension for the laminate was 150 N/m.

The plasma treatment devices 30a and 30b use atmospheric pressure plasma devices, and perform plasma irradiation at a power of 0.5 W·min/cm2 and a frequency of 50 kHz to 100 kHz. The plasma gas is set to 95% nitrogen, 5% dry air, and a total flow rate of 100 L/min/unit.

A pair of heating and pressurizing rollers 22 and 24 use rollers with a diameter of 6 inches, a width of 500 mm, a film pressurizing area of 2.6 cm2, and a pressurizing pressure of 150 MPa.

The electromagnetic induction heating device developed by our company is used as the heating devices 40a and 40b.

The temperatures of the thermoplastic polymer film 10 and the first copper foil 11a or the second copper foil 11b were calculated by the following method.

First, the surfaces of the thermoplastic polymer film 10 and the first copper foil 11a or the second copper foil 11b are observed by using a hyperspectral camera (Specim's "FX10") 41a, 41b, and the chromaticity a* value or b* value is calculated from the obtained reflection spectrum. The temperature of the thermoplastic polymer film 10 and the first copper foil 11a or the second copper foil 11b is calculated using a calibration curve from the above-calculated chromaticity a* value or b* value and the a* value or b* value previously obtained by the same method for a heating plate of known temperature. It should be noted that when using an infrared thermometer, if the thermoplastic polymer film 10, the first copper foil 11a or the second copper foil 11b changes color due to heating and the radiation coefficient changes, the temperature cannot be accurately measured. However, when using hyperspectral cameras 41a and 41b, the temperature can be accurately calculated from the calibration curve based on the color change. Not only the temperature of the observed part, but also the process of reaching the highest temperature of that temperature can be observed. [Evaluation method]

The bonding strength between the liquid crystal polymer film 10 and the first copper foil 11 a and the second copper foil 11 b was evaluated by measuring the peeling strength using a method based on IPC-TM-650.

The surfaces of the first copper foil 11a and the second copper foil 11b were visually observed, and the presence or absence of bubbles at the interface between the thermoplastic polymer film 10 and the first copper foil 11a and the second copper foil 11b was evaluated based on the presence or absence of pinholes or depressions.

Table 1 is a table showing evaluation results when a laminate is produced by respectively changing the heat pressing temperature in step S2 (heat pressing process), the heating temperature in step S3 (heating process), the heat pressing temperature in step S5 (heat pressing process), and the heating temperature in step S6 (heating process).

Table 1

As shown in Examples 1 to 4 of Table 1, when the heat pressing temperature in step S2 and step S5 (heat pressing process) is in the range of 170°C to 195°C and the heating temperature in step S3 and step S6 (heating process) is at 280°C, the peel strength is good and no pinholes or depressions are generated. It should be noted that in Example 4, the heat pressing temperature in step S5 is 5°C higher than the heat pressing temperature in step S2, and as a result, the bite between the thermoplastic polymer film 10 and the copper foil 11b is improved, and the peel strength of the back side can be improved to be substantially the same as that of the surface. As a result of setting the heating temperature of step S6 5° C. lower than the heating temperature of step S3 , foaming caused by the volatilization of water or low molecular weight substances generated from the thermoplastic polymer film 10 at the interface between the thermoplastic polymer film 10 and the second copper foil 11 b can be suppressed.

It was confirmed that the first copper foil 11a was temporarily bonded to the surface of the thermoplastic polymer film 10 by heat-pressing at a temperature near the softening temperature (170°C) of the thermoplastic polymer film 10, and then the back surface was opened, and then the thermoplastic polymer film 10 was heated at a temperature near the melting point (280°C). Then, the second copper foil 11b was heat-pressed at a temperature near the softening temperature (170°C) of the thermoplastic polymer film 10. 0 and then heated near the melting point (280°C) of the thermoplastic polymer film 10, which can maintain the bonding strength between the thermoplastic polymer film 10 and the first and second copper foils 11a, 11b, and prevent foaming caused by the entry of air at the interface between the thermoplastic polymer film 10 and the first copper foil 11a, 11b, and foaming caused by the volatilization of moisture or low molecular weight substances generated by the thermoplastic polymer film 10.

In contrast, as shown in Comparative Example 1, when the heat pressing temperature of the thermoplastic polymer film 10 and the first copper foil 11a and the second copper foil 11b was set to a temperature (160°C) lower than the softening temperature (170°C) of the thermoplastic polymer film 10, sufficient peel strength could not be obtained and foaming was observed. The reason is considered to be as follows: since the thermoplastic polymer film 10 is not sufficiently softened, it cannot fully enter the concave and convex surfaces of the first copper foil 11a and the second copper foil 11b and cannot exert an anchoring effect, and the temporary bonding between the thermoplastic polymer film 10 and the first copper foil 11a and the second copper foil 11b is insufficient. Therefore, even if the thermoplastic polymer film 10 is heated near the melting point (280°C) of the thermoplastic polymer film 10, the bonding strength cannot be improved, and the air that has entered the concave parts of the concave and convex surfaces of the first copper foil 11a and the second copper foil 11b has already foamed.

As shown in Comparative Example 2, when the thermoplastic polymer film 10 and the first copper foil 11a and the second copper foil 11b are hot-pressed at a temperature (200°C) that is 20°C higher than the softening temperature (170°C) of the thermoplastic polymer film 10, the thermoplastic polymer film 10 adheres to the heating and pressing rollers and breaks.

As shown in Comparative Example 3, when the heating temperature after temporary bonding is performed at a temperature (240°C) that is more than 20°C lower than the melting point (280°C) of the thermoplastic polymer film 10, the anchoring effect is insufficient, and therefore sufficient peeling strength cannot be obtained.

As shown in Comparative Example 4, when the heating temperature after the temporary bonding is performed at a temperature (350°C) that is more than 50°C higher than the melting point (280°C) of the thermoplastic polymer film 10, the thermal decomposition of the thermoplastic polymer film 10 is accelerated, and sufficient peeling strength cannot be obtained.

It should be noted that, as shown in Comparative Example 5, when the first copper foil 11a and the second copper foil 11b are heat-pressed on both surfaces of the thermoplastic polymer film 10 at a temperature near the melting point (280°C) of the thermoplastic polymer film 10, pinholes, bubbles, or depressions are generated at the interface between the thermoplastic polymer film 10 and the first copper foil 11a and the second copper foil 11b. Due to the generation of pinholes, bubbles, or depressions, sufficient peel strength cannot be obtained, and the insulation withstand voltage is significantly reduced.

10: Thermoplastic polymer film 11a: First copper foil 11b: Second copper foil 20: First roll-out shaft 21: Second roll-out shaft 22: A pair of first heating and pressurizing rollers 23: Third roll-out shaft 24: A pair of second heating and pressurizing rollers 25: Winding shaft 30a, 30b: Plasma treatment device 40a: First heating device 40b: Second heating device 41a, 41b: High-spectrum camera 50, 51, 52, 53, 54, 55, 56, 57: Guide rollers S1, S2, S3, S4, S5, S6: Steps

FIG1 is a flow chart showing each process of a method for manufacturing a laminate in one embodiment of the present invention. FIG2 is a diagram schematically showing a manufacturing apparatus for a laminate in one embodiment of the present invention.

Claims (12)

A method for manufacturing a laminate, characterized in that the laminate is manufactured by laminating copper foils on two surfaces of a thermoplastic polymer film, the method comprising process (A), process (B), process (C) and process (D), In process (A), a pair of heating and pressure rollers are introduced into the state where a first copper foil is overlapped on the surface of the thermoplastic polymer film, and the thermoplastic polymer film and the first copper foil are heat-pressed at a temperature at which the thermoplastic polymer film softens; In the aforementioned process (B), after the aforementioned process (A), the back side of the aforementioned thermoplastic polymer film on which the aforementioned first copper foil has not yet been laminated is left open, and the aforementioned thermoplastic polymer film is heated at a temperature close to the melting point of the aforementioned thermoplastic polymer film; In the aforementioned process (C), after the aforementioned process (B), a pair of heating and pressurizing rollers are introduced in a state where the second copper foil has been overlapped on the back side of the aforementioned thermoplastic polymer film, and the aforementioned thermoplastic polymer film and the aforementioned second copper foil are heat-pressed at a temperature at which the aforementioned thermoplastic polymer film softens; In the aforementioned process (D), the aforementioned thermoplastic polymer film is heated at a temperature close to the melting point of the aforementioned thermoplastic polymer film in a state where the aforementioned first copper foil and the aforementioned second copper foil are laminated on both surfaces of the aforementioned thermoplastic polymer film after the aforementioned process (C); The aforementioned process (A), the aforementioned process (B), the aforementioned process (C) and the aforementioned process (D) are continuously performed in a roll-to-roll manner. A method for manufacturing a laminate as described in claim 1, wherein in the aforementioned process (A) and the aforementioned process (C), the heat pressing temperature is: above the softening temperature of the aforementioned thermoplastic polymer film and below a temperature that is 20°C higher than the softening temperature of the aforementioned thermoplastic polymer film. A method for manufacturing a laminate as described in claim 1, wherein in the aforementioned process (B) and the aforementioned process (D), the heating temperature is: at least a temperature 20°C lower than the melting point of the aforementioned thermoplastic polymer film and at least a temperature 50°C higher than the melting point of the aforementioned thermoplastic polymer film. A method for manufacturing a laminate as recited in claim 1, wherein the heat pressing temperature in the aforementioned process (C) is set higher than the heat pressing temperature in the aforementioned process (A). A method for manufacturing a laminate as recited in claim 1, wherein the heating temperature in the aforementioned process (D) is set to be lower than the heating temperature in the aforementioned process (B). A method for manufacturing a laminate as described in claim 1, wherein in the aforementioned process (B) and the aforementioned process (D), the aforementioned first copper foil and the aforementioned second copper foil are heated respectively by electromagnetic induction using an induction heating coil, and the thermoplastic polymer film is heated by heat conduction from the aforementioned first copper foil and the aforementioned second copper foil. A method for manufacturing a laminate as described in claim 1, wherein in the aforementioned process (B) and the aforementioned process (D), the heating temperature is controlled by detecting the reflection spectrum of the surface of the aforementioned thermoplastic polymer film and/or the aforementioned first and second copper foils. The method for manufacturing a laminate as described in claim 1 further includes the following processes: a process of plasma treating the surface of the thermoplastic polymer film before the aforementioned process (A); a process of plasma treating the back surface of the thermoplastic polymer film after the aforementioned process (B) and before the aforementioned process (C). A method for manufacturing a laminate as recited in any one of claims 1 to 8, wherein the thermoplastic polymer film is composed of a liquid crystal polymer film. A manufacturing device for a laminate, characterized in that the laminate is manufactured by laminating copper foil on two surfaces of a thermoplastic polymer film in a roll-to-roll manner, and the manufacturing device for the laminate comprises a first unwinding shaft, a second unwinding shaft, a third unwinding shaft, a pair of first heating and pressurizing rollers, a first heating device, a pair of second heating and pressurizing rollers, a second heating device, and a winding shaft; The first unwinding shaft supplies the thermoplastic polymer film; The second unwinding shaft supplies the first copper foil; The third unwinding shaft supplies the second copper foil; The aforementioned pair of first heating and pressurizing rollers heat-press the aforementioned thermoplastic polymer film and the aforementioned first copper foil at a temperature at which the aforementioned thermoplastic polymer film softens, while the aforementioned first copper foil supplied by the aforementioned second unwinding roller is overlapped on the surface of the aforementioned thermoplastic polymer film supplied by the aforementioned first unwinding roller; The aforementioned first heating device heats the aforementioned thermoplastic polymer film laminated with the aforementioned first copper foil by the aforementioned pair of first heating and pressurizing rollers at a temperature close to the melting point of the aforementioned thermoplastic polymer film, and at this time, the back side of the aforementioned thermoplastic polymer film on which the aforementioned first copper foil has not yet been laminated is in an open state; The aforementioned pair of second heating and pressurizing rollers heat-presses the aforementioned thermoplastic polymer film and the aforementioned second copper foil at a temperature at which the aforementioned thermoplastic polymer film softens, while the aforementioned second copper foil supplied by the aforementioned third unwinding roller is superimposed on the back of the aforementioned thermoplastic polymer film heated by the first heating device; The aforementioned second heating device heats the aforementioned thermoplastic polymer film on which the aforementioned second copper foil is laminated by the aforementioned pair of second heating and pressurizing rollers, while the aforementioned first copper foil and second copper foil are laminated on both surfaces of the aforementioned thermoplastic polymer film, at a temperature close to the melting point of the aforementioned thermoplastic polymer film; The winding shaft winds up a laminated body in which copper foil is layered on both sides of the thermoplastic polymer film heated by the second heating device. The manufacturing device of the laminate as recited in claim 10, wherein the first heating device and the second heating device are respectively composed of electromagnetic induction heating devices, and the electromagnetic induction heating devices include induction heating coils for heating the first copper foil and the second copper foil by electromagnetic induction. The manufacturing device of the laminate as described in claim 10 further includes a first plasma treatment device and a second plasma treatment device; the first plasma treatment device performs plasma treatment on the surface of the thermoplastic polymer film before the first pair of heating and pressurizing rollers; the second plasma treatment device performs plasma treatment on the back of the thermoplastic polymer film before the second pair of heating and pressurizing rollers.