JP2002326308A - Heat-resistant flexible laminated sheet and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resistant flexible laminated sheet suitable as a flexible substrate material and having a low dimensional change ratio and good adhesiveness. SOLUTION: The heat-resistant flexible laminated sheet is obtained by laminating a metal foil and a heat-resistant adhesive film, and the peel strength of the metal foil at a peel angle of 180 deg. is not less than 10 N/cm and the dimensional change ratio before and after the removal of the metal foil is -0.1-+0.1%. This heat-resistant flexible laminated sheet is manufactured by a method including a process for molding the metal foil and the heat-resistant adhesive film in the nip between at least a pair of press rolls, under pressure and heating, between which protective materials are arranged, a process for cooling the obtained laminate and the protective materials while lightly bringing them into close contact with each other, and a process for peeling the protective materials from the laminate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In recent years, as electronic products have become lighter, smaller, and more dense, the demand for printed circuit boards, especially flexible laminates having a copper foil circuit formed on an insulating film has been increasing. . Generally, a flexible laminate is made by bonding a copper foil to an insulating film such as a polyimide film with a thermosetting adhesive (epoxy resin, acrylic resin, etc.) in a heated state, and further raising the temperature to cure the resin. A method of forming a circuit by etching a copper foil, or an insulating film on which a heat-resistant thermoplastic adhesive layer is formed in advance (hereinafter referred to as an adhesive film)
Is manufactured by bonding a copper foil in a heated state, and then etching the copper foil to form a circuit.

[0002] Flexible laminates have flexibility (flexibility) not available in rigid laminates. For example, they are usually used as substrates mounted on electronic devices such as video cameras, digital cameras, mobile phones, and notebook computers. Used in a bent state, these electronic devices can be reduced in size and weight,
In addition, the thickness can be reduced. The components mounted on the boards of these electronic devices are small and dense, so the wiring on the boards is fine, there is no dimensional change before and after the wiring pattern is formed by etching, and the copper foil It is required that there is no peeling off from the adhesive layer. If the adhesive strength between the metal foil and the adhesive layer is low, the interface between the metal foil and the adhesive layer is peeled off due to the bending of the substrate, and short-circuiting and disconnection of the wiring occur, thereby reducing the reliability of the circuit pattern.

[0003]

The flexible laminate has flexibility (flexibility) not available in the rigid laminate, and is used for applications that make use of the flexibility. For example, it is used for substrates mounted on electronic devices such as video cameras, digital cameras, mobile phones, and notebook computers that require small, light, and thin, and the substrates are bent and used to reduce the size of electronic devices. Is done. Also, in order to reduce the size and weight of electronic devices,
The wiring on the substrate becomes finer, and the components to be mounted are mounted with a smaller size and a higher density. Therefore, when forming a wiring pattern on the surface of a flexible substrate and processing it into a flexible printed wiring board, after forming the wiring pattern by etching the copper foil and the pattern before etching (resist formation) If the dimension of the substrate greatly changes, there is a problem that the component is not connected to the board because it is displaced from a component mounting position in a design stage.

Further, since the flexible substrate is used in a bent state as described above, if the adhesive strength between the copper foil and the adhesive layer is low, the substrate is bent to cause an interface between the copper foil and the adhesive layer. Is peeled off, and the reliability of the circuit pattern is reduced (the wiring is short-circuited or cut).

For example, a plasma display (PDP)
For high-performance flexible boards that require high heat resistance such as high-performance boards and multilayer boards, use a heat-resistant resin composition adhesive as described above and use existing epoxy and acrylic adhesives. Instead, those directly laminated with copper foil have begun to be used. The method includes a method of coating and forming a heat-resistant resin composition on a metal foil such as a copper foil, and a method of laminating and forming a heat-resistant adhesive film and a copper foil by a double belt press method. . On the other hand, metal / metal roll laminating technology is scarcely known, and there has been no flexible laminate manufactured by such a method until now. It has been said that it is difficult to achieve good appearance and to simultaneously satisfy all of dimensional stability and peel strength. According to the present invention, for the first time, it has become possible to provide a heat-resistant flexible laminate meeting these strict requirements with good productivity and low-cost equipment by this method.

[0006]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems of the conventional flexible laminate, and has a good heat-resistant flexible laminate having both good dimensional change rate and good copper foil peel strength. A manufacturing method is provided.

[0007] The present invention is a heat-resistant flexible laminate obtained by laminating a metal foil and a heat-resistant adhesive film, and has a metal foil peel strength of 10 N at a peel angle of 180 degrees.
/ Cm or more, and the dimensional change before and after the removal of the metal foil is in the range of -0.1 to + 0.1%.

The heat-resistant flexible laminate is laminated by a hot roll laminator having at least a pair of press rolls.

The above-mentioned heat-resistant flexible laminate is formed by disposing a protective material between at least one pair of press rolls and pressing and heating the metal foil and the heat-resistant adhesive film; The method includes a step of cooling while lightly adhering the material; and a step of peeling the protective material from the laminate.

[0010] Preferably, the press roll may be a metal roll.

Preferably, the step of pressurizing and heating is performed at a pressure in the range of 15 N / mm to 75 N / mm.

Preferably, the dimensional change rate is -0.05.
＋+ 0.05%.

Preferably, the heat-resistant adhesive film comprises:
The thermoplastic polyimide resin may be contained in an amount of 50% by weight or more.

Preferably, the heat-resistant adhesive film comprises:
It may be a thermoplastic polyimide resin having a glass transition temperature of 180 ° C. or higher.

In one aspect, the present invention relates to a method of manufacturing a heat-resistant flexible laminate comprising a metal foil and a heat-resistant adhesive film, the method comprising: forming at least one pair of the metal foil and the heat-resistant adhesive film. A step of disposing a protective material between press rolls and press-heating and molding; a step of cooling the obtained laminate and the protective material while keeping them in close contact with each other; and a step of peeling the protective material from the laminate. And the step of pressurizing and heat-forming can be performed at a pressure in the range of 15 N / mm to 75 N / mm.

Preferably, the step of pressurizing and heating is performed at a pressure in the range of 15 N / mm to 55 N / mm.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below.

Although the use of the laminate of the present invention is not particularly limited, it is mainly used as a flexible laminate for electronic and electric use.

The term "heat-resistant adhesive film" used in the present specification means a film-like material that is finally integrated as a laminate. Further, the term “protective material” as used herein means any material that is not a constituent material of the laminate.

The heat-resistant adhesive film used in the present invention preferably contains a thermoplastic resin, and the thermoplastic resin is preferably heat-resistant. For example, the heat-resistant adhesive film can be a molded product of thermoplastic polyimide, thermoplastic polyamideimide, thermoplastic polyetherimide, thermoplastic polyesterimide, or the like. Thermoplastic polyimide and thermoplastic polyesterimide can be particularly preferably used. A heat-fusible adhesive film containing 50% by weight or more of these heat-resistant thermoplastic resins is suitably used in the present invention. It is also preferable to use a heat-fusible adhesive film containing a thermosetting resin such as an epoxy resin or an acrylic resin. Further, if necessary, various additives known to those skilled in the art can be blended into the heat-fusible film in order to improve various properties.

The constitution of the heat-resistant adhesive film used in the present invention is not particularly limited, but as long as it has a certain degree of rigidity, sufficient insulating properties and adhesiveness, the adhesive layer 1
The adhesive layer may be a heat-resistant adhesive film or a three-layer structure using a rigid non-thermoplastic polyimide film at the center of the adhesive layer in order to obtain the rigidity of the adhesive material.

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. In addition, when the configuration of the adhesive film is composed of three layers of an adhesive layer / a core layer having no heat-fusing property / an adhesive layer, both sides of a core layer having no heat-fusing property (for example, a heat-resistant film) are provided. A method of producing a three-layer adhesive film by applying an adhesive to one side or both sides simultaneously, and disposing and bonding a single-layer adhesive film composed of only an adhesive component on both sides of a heat-resistant film, and bonding the three layers. It is produced by a method of forming a film.

A 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, particularly when a polyimide-based adhesive is used, A method in which imidization is performed while drying, a method in which a soluble polyimide resin is applied to a heat-resistant film as it is, and then dried. Each resin of an adhesive layer / a core layer having no heat-fusible property / adhesive layer is coextruded, and once There is a method of forming a heat-resistant adhesive film, and the like, but the method of forming the adhesive layer is not particularly limited.

In general, when the pressure at the time of lamination is low, the dimensional change rate of the obtained laminate tends to be small. After the copper foil is removed from the laminate by etching or the like, the dimensional change when left at 20 ° C. and 60% RH for 24 hours is −0 in both the MD direction (the film advancing direction) and the TD direction (the film width direction). In order to be in the range of 0.1% to + 0.1%, it is preferable to laminate at a pressure of 75 N / mm or less. When laminating at a pressure of 75 N / mm or more, the dimensional change rate becomes larger than 0.1%. Further, the dimensional change rate is from -0.05% to +0.
In order to reduce the thickness to the range of 05%, it is more preferable to laminate at a pressure of 55 N / mm. However, if the pressure is excessively lowered, the peel strength tends to be weak. Therefore, the peel strength at a peel angle of 180 ° is 10 N / cm or more, and the peel interface is cohesive failure of the adhesive layer (A / Pi fracture). Requires a pressure at the time of lamination of 15 N / mm or more. If the lamination pressure is lower than 15 N / mm, the peel strength will be lower than 10 N / cm,
Peeling interface also peels between copper foil and adhesive layer (C / A destruction)
There is a tendency. If the peeling interface is C / A destruction, other physical properties such as solder heat resistance also deteriorate.

The types of copper foil used in the present invention include:
Without limitation, rolled copper foil, electrolytic copper foil, HTE copper foil, etc. can be used, and an adhesive is applied to the surface thereof, and a chemical or mechanical surface such as blackening treatment, coupling agent treatment, etc. Processing may be performed.

The hot roll laminating apparatus can be used without limitation as long as it is an apparatus for laminating by applying pressure by heating. Regarding the heating method, any method capable of heating at a predetermined temperature can be adopted, and a heat medium circulation method, a hot air heating method, an induction heating method, or the like can be used. The pressurizing method is not particularly limited as long as a predetermined pressure can be applied, and a hydraulic method, a pneumatic method, a gap pressure method, or the like can be used.

The hot roll laminating device is a device for laminating a pair of press rolls with a linear pressure in the surface length direction, and has a higher pressing force than the surface pressure of a press plate such as a single-acting press machine or a vacuum press machine. Is extremely high, so that even a heat-resistant adhesive material having a Tg of 250 ° C. or more can be laminated at a pressure that cannot be achieved by a press. The material of the surface of the pair of press rolls of the hot roll laminating apparatus includes metal-metal, rubber-rubber, and rubber-metal combinations. The material of the press roll is not particularly limited, but lamination is performed at a temperature exceeding 250 ° C. In this case, it is preferable to have a press roll made of metal-metal.

The laminating temperature in the hot roll laminating apparatus is preferably a temperature of Tg + 50 ° C. or more of the heat-resistant adhesive material, and more preferably Tg + 100 ° C. or more of the heat-resistant adhesive material in order to increase the laminating speed. The laminating speed is 0.5 m / m from the viewpoint of manufacturing a laminate.
In or more is preferable. To further increase productivity,
1.0 m / min or more is more preferable. The higher the lamination pressure, the lower the lamination temperature, and
Although there is an advantage that the laminating speed can be increased, if the laminating pressure is too high, the dimensional change of the laminate tends to be worse as described above.

The protective material must be able to withstand the temperature during processing. For example, when processed at 250 ° C., a polyimide film having higher heat resistance such as copper foil, aluminum foil, SUS foil, etc. Metal foil is used effectively. When a commercially available polyimide film is used, the thickness of the protective material is preferably 75 μm or more from the viewpoint of suppressing the formation of wrinkles in the laminated plate after lamination.

The temperature of the laminate at the time of peeling the protective material is as follows:
The temperature is preferably equal to or lower than the Tg of the thermoplastic resin of the laminate in order to suppress wrinkling of the laminate after lamination. More preferably, the temperature is at least 50 ° C. lower than Tg, and still more preferably, at least 100 ° C. lower than Tg. Most preferably, the protective material is peeled from the laminate when cooled to room temperature.

In the present invention, the above-mentioned protective material can be used repeatedly. In addition to installing the feeding and winding device for the material to be laminated before and after the hot roll laminating device, by adding the feeding and winding device for the protective material, the protective material once used in the laminating device can be used. The protective material can be reused by rewinding by the winding device and re-installing it on the payout side. At the time of winding, an end position detecting device and a winding position correcting device may be installed, and the ends of the protective material may be precisely aligned and wound.

Hereinafter, the present invention will be described in more detail by way of examples.

[0033]

The present invention will be described in detail with reference to examples of the present invention and comparative examples. The following examples are illustrative of the present invention and do not limit the present invention.

Hereinafter, in Examples and Comparative Examples, the physical properties of the adhesive layer and the physical properties of the flexible substrate were measured by the following measuring methods.

(Dimensional change rate) Based on JIS C6481, the distance of each of the four holes formed in the laminate was measured, and then the copper foil was removed by etching.
It was left in a constant temperature room at 60% RH for 24 hours, and the distance between each of the four holes was measured as before the etching, and the dimensional change rate was obtained by the following formula: dimensional change rate (%) = [(copper foil Measured value of film after removal-measured value before copper foil removal) / (measured value before copper foil removal)] ×
100 (peel strength) A sample was prepared in accordance with JIS C6471 “6.5 Peel Strength”, and a copper foil portion having a width of 5 mm was peeled at a peel angle of 180 ° and a condition of 50 mm / min. It was measured.

(Examples 1 to 5) Adhesive film having a thickness of 25 μm and having a three-layer structure having a thermoplastic polyimide resin component having a Tg of 190 ° C. on the front and back surfaces of a non-thermoplastic polyimide film )
18 μm rolled copper foil (Japan Energy BHY-22B-T) is arranged on the front and back surfaces, and a 125 μm polyimide film (Kanebuchi Chemical Industry Co., Ltd. Apical 125AH) is arranged as a protective film on the outside. Then, lamination was performed by a hot roll laminator under lamination conditions in which the linear pressure (N / mm) was changed as shown in Table 1 to obtain a laminate.

In Table 1, the linear pressure is the pressure per unit length applied to the object to be laminated by a pair of press rolls, and the linear velocity is the peripheral edge of the metal roll, that is, the pressing surface of the metal roll. And the fracture interface is
A / Pi indicates a place where destruction occurs in a peel test.
The fracture interface is between the adhesive layer and the base film, and C / A indicates that the fracture interface is between the copper foil and the adhesive layer, respectively.

With respect to the obtained laminate, the peel strength and the dimensional change were measured, and the results are shown in Table 1. Table 1
As shown in the figure, each of the obtained laminates was 10 N / c
m, and the dimensional change was small.

(Comparative Examples 1 and 2) The same materials as in Example 1 were used, and as shown in Comparative Examples 1 and 2 in Table 1, 15N
The laminate was obtained by laminating under a laminating condition using a linear pressure of / mm or less. When the peel strength and the dimensional change rate of the obtained laminate were measured, as shown in Table 1, the obtained laminate had a small dimensional change rate.
Peeling was performed at N / cm (the peeling interface was C / A destruction between the copper foil and the adhesive layer), and the adhesive strength was low.

Comparative Examples 3 and 4 The same materials as in Example 1 were used, and as shown in Comparative Examples 3 and 4 in Table 1, 75 N
The laminate was obtained by laminating under a laminating condition using a linear pressure of / mm or more. When the peel strength and the dimensional change rate of the obtained laminate were measured, as shown in Table 1, the obtained laminate had good adhesive strength, but the dimensional change was large. Was.

[0041]

[Table 1]

[0042]

According to the present invention, there is provided a heat-resistant flexible laminate having a good step change ratio and excellent adhesiveness, and a method for producing the same.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // B29K 79:00 B29K 79:00 B29L 7:00 B29L 7:00 9:00 9:00 (72) Inventor Kataoka Kousuke 2-4-64 Sakamoto, Otsu-shi, Shiga Prefecture (72) Inventor Yasuo Fushiki 33-1-702 Otowa Maedemachi, Yamashina-ku, Kyoto F-term (reference) 4F100 AB01A AB17A AB33A AK49B BA02 EJ192 EJ503 EJ912 GB43 JA05B JB16B JJ03B JK02 JK17L JL04 JL11B YY00 YY00B 4F211 AA40 AC03 AG03 AH36 AJ02 AR02 TA01 TA03 TC05 TN09 TQ03 TW45

Claims (10)

[Claims] 1. A heat-resistant flexible laminate obtained by laminating a metal foil and a heat-resistant adhesive film, wherein the metal foil has a peel strength of 10 N / cm or more at a peel angle of 180 ° and a metal foil. The dimensional change before and after removal is-
A heat-resistant flexible laminate in the range of 0.1 to + 0.1%. 2. The lamination by a hot roll laminating apparatus having at least a pair of press rolls.
2. The heat-resistant flexible laminate according to item 1. 3. The heat-resistant flexible laminate according to claim 1, wherein a protective material is placed between at least one pair of press rolls and the metal foil and the heat-resistant adhesive film are pressed and heated. A heat-resistant flexible laminate, which is produced by a method comprising the steps of: cooling the obtained laminate and the protective material while keeping them in close contact with each other; and peeling the protective material from the laminate. 4. The heat-resistant flexible laminate according to claim 2, wherein the press roll is a metal roll. 5. The step of pressurizing and heating is performed at 15 N / mm.
The heat-resistant flexible laminate according to claim 3, wherein the heat-resistant flexible laminate is performed at a pressure in the range of −75 N / mm. 6. The dimensional change rate is -0.05 to +0.0.
The heat-resistant flexible laminate according to claim 1, wherein the range is 5%. 7. The heat-resistant adhesive film contains 50% by weight or more of a thermoplastic polyimide resin.
The heat-resistant flexible laminate according to any one of the above. 8. The heat-resistant flexible laminate according to claim 1, wherein the heat-resistant adhesive film is a thermoplastic polyimide resin having a glass transition temperature of 180 ° C. or higher. 9. A method for manufacturing a heat-resistant flexible laminate comprising a metal foil and a heat-resistant adhesive film, comprising: disposing a protective material between the metal foil and the heat-resistant adhesive film between at least one pair of press rolls. Pressing and heating;
A step of cooling the obtained laminate and the protective material while keeping them in close contact with each other; and a step of peeling the protective material from the laminate, wherein the step of pressurizing and heat-forming is 15 N / mm to 75 N / m
m, performed at a pressure in the range of m. 10. The step of forming under pressure and heat is performed at 15 N /
10. The process is performed at a pressure in the range of mm to 55 N / mm.
The method described in.