JP2009141337A - Metal laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To economically manufacture a flexible metal laminate and a flexible printed board that are excellent in flexibility, folding endurance, heat resistance reliability, moisture resistant reliability, absorbency, and dimensional accuracy. <P>SOLUTION: The flexible metal laminate comprises a heat resistant resin film having at least one side laminated with a metal foil, wherein the heat resistant resin film is a thermoplastics resin that comprises two layers, and has adhesive strength of 4N/cm or more after it is treated for 500 hours while being heated at 85°C and humidified at 85%RH using a sample having a circuit pattern created by a subtractive method according to IPC-FC241 (IPC-TM-650, 2. 4. 9 (A)), and wherein a heat resistant resin film layer contacting the metal foil side has a Tg of 350 °C or higher. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flexible metal laminate in which a metal foil is laminated on at least one surface of a heat-resistant resin film, and a flexible printed circuit board. More specifically, the present invention is excellent in flexibility, folding resistance, insulation, and solder processing. The present invention relates to a flexible metal-clad laminate and a flexible printed circuit board that are excellent in heat resistance reliability such as adhesive strength later, moisture resistance reliability such as adhesive strength after humidification treatment, and dimensional accuracy such as humidity dimensional change rate.

  In the present specification and claims, the term “flexible metal-clad laminate” refers to a laminate formed from a metal foil and a resin layer, and is useful for the production of, for example, a flexible printed circuit board. It is. The “flexible printed circuit board” can be manufactured by a conventionally known method such as a subtractive method using, for example, a flexible metal-clad laminate, and covers a conductor circuit partially or entirely as required. So-called flexible circuit board (FPC), flat cable, circuit board for tape automated bonding (TAB), or circuit board for mounting TCP (tape carrier package) covered with lay film or screen printing ink (Chip-on-flexible substrates, etc.) are generic names.

  A conventional flexible metal-clad laminate for a flexible printed circuit board is obtained by bonding a polyimide film and a metal foil with an adhesive such as a rubber-modified epoxy resin or acrylic resin. The flexible printed circuit board formed from the flexible metal-clad laminate bonded with this adhesive is inferior in heat resistance, dimensional stability, insulation reliability, etc., because the heat resistance of the adhesive is significantly inferior to that of the polyimide film. There was a problem.

In order to solve these problems, a technique for forming a metal-clad laminate (two-layer CCL) having a two-layer structure without an adhesive layer by directly applying a polyimide resin solution to a metal foil has been proposed. (For example, refer to Patent Documents 1 and 2). However, these two-layer CCL
-Since the polyimide resin to be applied is insoluble in an organic solvent, it is necessary to imidize by applying a high temperature heat treatment on the metal foil after applying the precursor polyamic acid solution. Therefore, it is inferior to workability.
-Since the elastic modulus of the resin film layer formed on the metal foil is high, the flexible printed circuit board is inferior in the bending resistance and folding resistance.
There are disadvantages such as.

  In order to improve the processability, bending resistance, and folding resistance as described above, in Patent Document 3, a resin composition that is soluble in an organic solvent and has a low film modulus is directly applied to a metal foil. A technique for forming a two-layer CCL by drying is proposed. However, although the resin composition used here is excellent in workability and bending resistance, it is inferior in dimensional accuracy such as the humidity dimensional change rate after circuit processing of the copper foil. There is a drawback that it is not suitable for use in what is mounted (TCP mounting), so-called COF substrate (chip-on-flexible substrate). Moreover, since it is inferior in reliability of peel strength (adhesive strength), for example, peel stability after humidification, etc., there is a disadvantage that it is not suitable for circuit board applications requiring a fine pitch.

JP-A-57-50670 JP-A-57-66690 JP 2001-105530 A

  An object of the present invention is to solve the above-described problems, and includes a flexible metal laminate for a flexible printed circuit board and the like, and a flexible printed circuit board such as a circuit board that requires a fine pitch such as COF. It is intended to be manufactured at low cost. That is, an object of the present invention is to provide a flexible metal-clad laminate and a flexible printed circuit board made of a substrate material that is excellent in flexibility and folding resistance, has a low humidity dimensional change rate, and has excellent heat resistance reliability and moisture resistance reliability. It is about.

  As a result of diligent research to achieve the above object, the present inventors have found a resin composition that is not conventional and is soluble in solvent and excellent in heat resistance, and a layer structure as a flexible printed board including these materials, As a result of intensive studies on processing methods, etc., this has been achieved.

That is, this invention is the following flexible metal-clad laminates and flexible printed boards.
(1)
A flexible metal laminate in which a metal foil is laminated on at least one surface of a heat resistant resin film, and a circuit pattern is formed by a subtractive method according to IPC-FC241 (IPC-TM-650, 2.4.9 (A)). Using the prepared sample, the adhesive strength after being treated for 500 hours under heating and humidification at 85 ° C. and 85% RH is 4 N / cm or more, and the heat-resistant resin film comprises two layers. A flexible metal laminate, wherein the heat-resistant resin film layer on the side in contact with the metal foil is a thermoplastic resin having a Tg of 350 ° C. or higher.
(2)
A flexible metal laminate in which a metal foil is laminated on one side of a heat resistant resin film, the heat resistant resin film comprising two layers, and the thickness (T1) of the resin layer on the side in contact with the metal foil and the metal foil The flexible metal laminate according to (1), wherein the ratio (T1) / (T2) of the thickness (T2) of the resin layer on the non-contact side is 0.05 to 5.
(3)
The flexible metal laminate according to (1) or (2), wherein the heat-resistant resin film is soluble in an organic solvent and is a thermoplastic polyamideimide resin.
(4)
The flexible metal laminate according to any one of (1) to (3), wherein a metal foil is formed on one side, wherein the heat-resistant resin layer on the side in contact with the metal foil is
a) When the total amount of the acid component is 100 mol%, the total amount of the amine component is 100 mol%, and the total of the acid component and the amine component is 200 mol%, the monomer component having a naphthalene group is 80 mol% or more,
And b) a molar ratio of imide bond to amide bond is 99/1 to 60/40 molar ratio,
c) A flexible metal laminate characterized by being a polyamide-imide resin having an imidization rate of imide bonds of 50% or more.
(5)
The flexible metal laminate according to any one of (1) to (4), wherein a metal foil is formed on one side, and the resin layer on the side not in contact with the metal foil,
a) When the total amount of the acid component is 100 mol%, the total amount of the amine component is 100 mol%, and the total of the acid component and the amine component is 200 mol%, the monomer component having a biphenylene group is 100 mol% or more,
And b) a molar ratio of imide bond to amide bond is 99/1 to 65/35 molar ratio,
c) A flexible metal laminate characterized by being a polyamide-imide resin having an imidization rate of imide bonds of 50% or more.
(6)
The double-sided flexible metal laminated body obtained by bonding together the flexible metal laminated body in any one of (1)-(5) so that metal foil may be formed in both surfaces.
(7)
A flexible printed circuit board obtained from the flexible metal-clad laminate according to any one of (1) to (6).

  The flexible metal laminate of the present invention is composed of a plurality of resin compositions having low flexibility, folding resistance, humidity dimensional change rate, and high Tg, and the folding resistance, flexibility, dimensions, depending on the layer configuration and processing conditions. Excellent in terms of accuracy, moisture resistance reliability, heat resistance reliability, and the like. Furthermore, since the resin composition to be used is soluble in an organic solvent, it can be produced at low cost without the need for heat treatment at high temperatures. Therefore, since a flexible substrate that can be used even for high-density mounting substrate applications can be manufactured at low cost, there are significant industrial advantages.

  The heat resistant resin film of the flexible metal laminate of the present invention is formed of at least two layers. That is, the heat-resistant resin film is composed of two layers: a first resin layer in contact with the metal foil side and a second resin layer laminated on the first resin layer. A metal foil is laminated on one side. The first resin layer refers to a resin layer in contact with a metal foil side such as a copper foil in the flexible metal laminate of the present invention. The second resin layer refers to a resin layer further laminated on the first layer. Of the two layers, the heat-resistant resin film layer on the side in contact with the metal foil needs to be a thermoplastic resin having a Tg of 350 ° C. or higher. Moreover, the flexible metal laminated body of this invention is 85 degreeC, 85 using the sample which created the circuit pattern by the subtractive method according to IPC-FC241 (IPC-TM-650, 2.4.9 (A)). It is necessary that the adhesive strength between the circuit pattern and the heat-resistant resin film after being treated for 500 hours under heating and humidification of% RH is 4 N / cm or more.

In the present invention, the heat-resistant resin film has a two-layer structure, but if the heat-resistant resin film has a single-layer structure, the peel strength (adhesive strength) in the normal state (25 ° C., 65% RH) may be good. At the same time, it is difficult to simultaneously satisfy the reliability of the characteristics such as the adhesive strength after the humidification atmosphere or after the humidification treatment, or the adhesion strength after the heat treatment such as the heating atmosphere or after the solder treatment. In the present invention, it is necessary that the structure has two or more layers.
In the present invention, the first layer is laminated with a thermoplastic resin having a good adhesion to a metal foil such as copper foil and having a relatively high polarity and a Tg of 350 ° C. or more. By laminating resins with excellent moisture absorption properties such as moisture content and moisture absorption rate, it is possible to obtain a metal laminate that can exhibit stable properties, particularly in the reliability of peel strength (adhesive strength), in any atmosphere. Features.
In particular, in circuit board applications where fine pitch such as COF is required, the adhesive strength after processing for 500 hours under heating and humidification at 85 ° C. and 85% RH is 4 N / cm or more, as usual. More preferably, the adhesive strength is 6 N / cm or more, and still more preferably 8 N / cm or more. When the adhesive strength is less than 4 N / cm, if the circuit width is narrowed, circuit peeling or floating occurs and reliability is lowered, which is not desirable. There is no particular upper limit because the higher the adhesive strength after treatment for 500 hours under heating and humidification at 85 ° C. and 85% RH, the better. However, if it is about 25 N / cm, it is sufficient as performance, and although it cannot be said more generally than required performance, it may be 20 N / cm or less, and further 15 N / cm or less.
The difference in solubility parameter between the two resin film layers is preferably (2.0) or less, more preferably (1.5) or less, and even more preferably (1.0) or less. If the difference in solubility parameter exceeds (2.0), the peel strength (adhesion strength) is reliable, especially in high-density circuits after humidification treatment, adhesion between the metal foil interface and two resin layers. It tends to be unfavorable because the properties may decrease.

  In the flexible metal laminate of the present invention, the Tg of the first layer of thermoplastic resin in contact with the metal foil side is 350 ° C. or higher, preferably 380 ° C. or higher, more preferably 400 ° C. or higher. If Tg is less than 350 ° C., the heat resistance, in particular, the adhesive strength after soldering and the like is lowered, which is not desirable. The higher the Tg of the thermoplastic resin in contact with the metal foil side, the better, and there is no upper limit. However, the temperature of about 500 ° C. is sufficient, and the required performance cannot be generally specified. However, even if the Tg of the thermoplastic resin in contact with the metal foil side is 450 ° C. or less, there is no problem.

  Here, the adhesive strength can be measured using a sample in which a circuit pattern is created by a subtractive method according to IPC-FC241 (IPC-TM-650, 2.4.9 (A)). The solubility parameter can be calculated by a conventionally known method, for example, the Fedor method.

  The heat-resistant resin film used in the present invention is a resin classified into the category of so-called engineering plastics, which has excellent heat resistance, such as polyimide, polyamideimide, polyetherimide, polyesterimide, polyparabanic acid, polyarylate, and aramid. If you can, you can use it. From the viewpoint of heat resistance, dimensional accuracy, etc., preferably polyimide and polyamideimide, and from the viewpoint of workability described later, more preferably soluble in an organic solvent and / or thermoplastic polyimide and polyamideimide, Preferably, it is soluble in an organic solvent and / or is a thermoplastic polyamideimide.

[First resin layer]
The heat resistant resin film of the flexible metal laminate of the present invention is composed of two layers. Of the two layers, the first resin layer refers to a resin layer in contact with the metal foil side such as a copper foil in the flexible metal laminate of the present invention. The resin in the first layer needs to be a thermoplastic resin having a Tg of 350 ° C. or higher.
One preferred embodiment of the thermoplastic resin having a Tg of 350 ° C. or higher used for achieving the object of the present invention is as follows.
In the first resin layer, when the total amount of the acid component is 100 mol%, the total amount of the amine component is 100 mol%, and the total amount of the acid component and the amine component is 200 mol%, the monomer having a naphthalene group is 80%. A mol% or more polyamideimide is preferred. For the monomer having a naphthalene group, the total amount of the acid component is 100 mol%, the total amount of the amine component is 100 mol%, and the total amount of the acid component and the amine component is 200 mol%, more preferably 90 mol% or more, Even more preferably, it is 100 mol% or more. If the naphthalene group is less than 80 mol%, the moisture absorption property tends to deteriorate, and the moisture resistance reliability such as peel strength (adhesion strength) after the humidification treatment may not satisfy the requirements of the present invention. Since it decreases, the heat resistance reliability such as peel strength (adhesion strength) after soldering tends to decrease.
In addition, the monomer having a naphthalene group is preferably 170 mol% or less when the total amount of the acid component is 100 mol%, the total amount of the amine component is 100 mol%, and the total amount of the acid component and the amine component is 200 mol%. More preferably, it is 160 mol% or less, and still more preferably 150 mol% or less. When it exceeds 170 mol%, the elastic modulus increases and the solubility tends to decrease.
The molar ratio of the imide bond and the amide bond of the polyamideimide is preferably 99/1 to 60/40, more preferably 99/1 to 75/25, and even more preferably 90/10 to 80 /. 20 When the molar ratio of the imide bond to the amide bond is less than 60/40, the heat resistance, the moisture resistance reliability, and the heat resistance reliability tend to be poor, and in particular, the adhesive strength after soldering tends to decrease. On the other hand, if it exceeds 99/1, the elastic modulus increases, and the folding resistance and bending characteristics tend to decrease. Further, since the solubility is poor, the workability of the flexible metal laminate tends to be deteriorated.
One preferred embodiment includes the unit represented by the general formula (1) as an essential component, and is further selected from the group represented by the general formula (2), the general formula (3), and the general formula (4). It is a polyamide-imide resin that contains at least one unit as a repeating unit in the molecular chain. Here, in the general formula (2), X is SO2 or direct connection (biphenyl), especially from low elastic modulus, high heat resistance (Tg, peel stability after soldering, etc.), and adhesiveness with copper foil. ) Or n = 0, and more preferably, direct connection (biphenyl) or n = 0. In general formula (3), Y is similarly benzophenone type (CO), or low elastic modulus, high heat resistance (Tg, peel stability after soldering, etc.), and adhesiveness with copper foil, or Direct connection type (biphenyl) is preferred. The units represented by the following general formula (2) and general formula (3) may be one type or two or more types, respectively. In the first-layer thermoplastic resin, a substituent may be bonded to the naphthalene skeleton or the benzene skeleton.
According to IPC-FC241 (IPC-TM-650, 2.4.9 (A)), using a sample in which a circuit pattern was created by a subtractive method, heating at 85 ° C., 85% RH, under humidification for 500 hours The adhesive strength after the treatment and the Tg of the thermoplastic resin on the side in contact with the metal foil are preferably higher, but in order to make it higher, the component ratio of the general formula (1) is decreased. Means such as increasing the proportion of bonds and increasing the amount of naphthalene groups are preferred.

The content ratio of the general formula (1), the general formula (2), the general formula (3), and the general formula (4) is a molar ratio of {general formula (1)} / {general formula (2) + general formula ( 3) + General formula (4)} = 1/99 to 40/60 (molar ratio), and the molar ratio of the imide bond to the amide bond is 99/1 to 60/40 molar ratio. It is preferable that More preferably, {general formula (1)} / {general formula (2) + general formula (3) + general formula (4)} = 10/90 to 30/70. The molar ratio is 99/1 to 75/25. Even more preferably, {general formula (1)} / {general formula (2) + general formula (3) + general formula (4)} = 10/90 to 20/80, and the mole of imide bond and amide bond. The ratio is 90/10 to 80/20.
When this content ratio {general formula (1)} / {general formula (2) + general formula (3) + general formula (4)} exceeds 40/60 or is lower than 1/99, heat resistance It tends to be difficult to achieve both compatibility (Tg), low elastic modulus, and adhesion with copper foil. In particular, when it exceeds 40/60, the heat resistance is deteriorated, and when it is lower than 1/99, the solubility in a solvent is poor, and the elastic modulus of the resin film is increased, so that the bending resistance and folding resistance are increased. Tend to decrease. On the other hand, when the molar ratio of the imide bond to the amide bond is less than 60/40, the heat resistance, moisture resistance reliability, and heat resistance reliability are poor, and the adhesive strength after soldering tends to decrease. On the other hand, if it exceeds 99/1, the elastic modulus increases, and the folding resistance and bending characteristics tend to decrease. Further, since the solubility is poor, the workability of the flexible metal laminate tends to be deteriorated.

Further, from the viewpoint of heat resistance and moisture absorption characteristics, a particularly preferred embodiment is a molar ratio of the amide-forming component of the general formula (2) and the imide-forming component of the general formula (3) and / or the general formula (4). The ratio is preferably adjusted to {general formula (2)} / {general formula (3) + general formula (4)} = 5/95 to 95/5. If the content of {general formula (2)} in general formula (2) and general formula (3) and / or general formula (4) is less than 5 mol%, the moisture absorption properties tend to be poor. On the other hand, if it exceeds 95 mol%, the heat resistance tends to deteriorate. In one preferred embodiment, the general formula (1) is a repeating unit from trimellitic anhydride and 1,5-naphthalene diisocyanate, the general formula (2) is a repeating unit from terephthalic acid and 1,5-naphthalene diisocyanate, (3) is a repeating unit from biphenyltetracarboxylic dianhydride and / or benzophenonetetracarboxylic dianhydride and 1,5-naphthalene diisocyanate, and the content ratio thereof is represented by the general formula (1) / {general formula ( 2) + general formula (3) + general formula (4)} = 1/99 to 40/60 molar ratio and general formula (2) / general formula (3) = 10/90 to 90/10 molar ratio Is preferred.

  In the above, when the content of general formula (1) in general formula (1), general formula (2), general formula (3), and general formula (4) exceeds 40 mol%, Hygroscopic properties are lowered, and if it is less than 1 mol%, the solvent solubility of the resin tends to be poor and the film modulus tends to be high. Moreover, when the content of the general formula (2) in the general formula (2), the general formula (3), and the general formula (4) is less than 10 mol%, the moisture absorption property tends to be lowered, and 90 mol If it exceeds 50%, the solvent solubility of the resin may deteriorate.

  In the above embodiment, common preferred embodiments will be described. In the general formula (2), it is particularly preferable that the bond ratio of the ratio in which the amide bond is in the para position and the ratio in the meta position satisfies para position / meta position = 5/95 to 100/0 mol%. More preferably, the bond ratio of the ratio in which the amide bond is in the para position and the ratio in the meta position satisfies the para position / meta position = 20/80 to 100/0 mol%, most preferably the para position. / Meta position = when satisfying 50/50 to 100/0 mol%. When the para position is 5 mol% or less, the effect of improving the heat resistance tends to decrease.

  Further, these polyamide-imide resins are preferably non-halogen-based resins that do not contain halogens such as fluorine, chlorine, bromine, and iodine from the viewpoint of environmental considerations.

The imidization rate of the polyamide-imide resin is preferably 50% or more, more preferably 90% or more, and still more preferably 95% or more. The higher the imidization rate, the more preferable the upper limit is 100%. If the imidization rate of the imide bond is less than 50%, the adhesiveness with the resin of the second layer laminated on the resin film of the first layer tends to be low, and peeling between the resin layers occurs. It tends to be easy, and the peel strength may decrease after soldering or after humidification. As a result, reliability such as folding resistance, flexibility, heat resistance reliability, moisture resistance reliability, etc. tends to be poor.
The reason for this is that if the second layer is laminated before the imidization reaction of the first layer is completed, the imidization reaction accompanying the heating proceeds in the subsequent heating step, and it occurs accordingly. It is presumed that the condensed water adversely affects the adhesiveness at the resin layer or at the interface between the resin and the metal foil. Therefore, it is preferable to manufacture the resin composition used in the present invention by a method such as an isocyanate method described later so that the imidization rate of the obtained resin varnish is completed after polymerization. At this time, the polyamideimide resin is preferably soluble in an organic solvent. In addition, it is preferable to pay attention to the production conditions since the imidization reaction may not be completed after polymerization due to the purity of the monomer and the influence of the solvent type even in the production by the isocyanate method. In order to increase the imidization ratio to 50% or more, in the case of the amine method, a precursor is synthesized by a usual method, and after film formation, the temperature is gradually increased to Tg or more, and around Tg (plus or minus 10 ° C.) It is preferable to heat for about 1 hour and perform sufficient imidization treatment. In the isocyanate method, it is preferable to reduce the moisture content to 50 mol% or less of the number of moles of the monomer or to increase the purity of the monomer, for example, using a trimellitic anhydride having a high cyclization rate in the diisocyanate component. It is desirable that the monomer purity is high, for example, the amount of the diamine component which is an impurity is small.
In addition, the measurement of imidation rate can be calculated | required by the method as described in the below-mentioned Example.

Moreover, it is preferable that these polyamideimide resins are soluble in an organic solvent also from the workability at the time of making the flexible metal-clad laminate and the laminated film with an adhesive layer described later. The organic solvents mentioned here are N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, tetramethylurea, sulfolane, dimethyl. It is at least one selected from the group consisting of sulfooxide, γ-butyrolactone, cyclohexanone and cyclopentanone, or a part of these is a group consisting of toluene, xylene, diglyme, triglyme, tetrahydrofuran, methyl ethyl ketone and methyl isobutyl ketone. It shall be replaced with at least one selected from the above. In the present invention, being soluble in an organic solvent means that any one of the above-mentioned single solvents or a mixed organic solvent containing 20% or more of at least one of them is 10% by weight or more. It is preferable to dissolve. More preferably, it is 15 weight% or more, More preferably, it is 20 weight% or more. In addition, when the resin is in a solid state, whether or not it has been dissolved is determined by adding a specified weight of resin powder passing through 80 mesh into a 200 ml beaker and gently stirring at 25 ° C. for 24 hours. It was determined that it was dissolved at 25 ° C. for 24 hours, and the solution that was not gelled, non-uniformized, clouded, or precipitated was dissolved.

In order to be soluble in a solvent, (1) the above-described preferred resin composition is used, (2) the ratio of imide group / amide group is lowered (3) a polycarboxylic acid component having an alicyclic group, polyamine described later Copolymerized as a component, (4) a polycarboxylic acid component having an aliphatic group, which will be described later, copolymerized as a polyamine component, (5) a flexible group is introduced into the aromatic ring, (6) a bulky in the polymer chain (7) The polymer is modified with an epoxy compound described later.
Etc. can be achieved.

  As described above, with the naphthalene skeleton as the main skeleton and the bond ratio set to a specific ratio, the rigidity / flexibility of the polymer chain itself, the intermolecular force between the polymer chains, the plane orientation, etc. are well balanced. In addition, the objects of the present invention such as solvent solubility, low elastic modulus, and heat resistance can be achieved.

(X represents an oxygen atom, CO, SO2, or direct connection, and n represents 0 or 1)

(Y represents an oxygen atom, CO, or OOC-R-COO, n represents 0 or 1, and R represents a divalent organic group.)

In the first layer thermoplastic resin on the side in contact with the metal foil, an example of a preferable means for achieving a desired Tg has been described above, but the present invention is not limited thereto. That is, if appropriate molecular design is performed to reduce the entropy change before and after melting or transition, reduce the flexibility of the molecule, improve the intermolecular force, improve the packing property, and reduce the bulkiness. Good.

[Second resin layer]
Here, the second resin layer refers to a resin layer laminated on the first resin layer.
Heating at 85 ° C. and 85% RH using a sample in which a circuit pattern was created by a subtractive method according to IPC-FC241 (IPC-TM-650, 2.4.9 (A)) for a metal laminate In order to make the adhesive strength between the circuit pattern and the heat-resistant resin film 4N / cm or more after the treatment for 500 hours in the above, the second layer resin is excellent in moisture absorption characteristics such as moisture permeability and moisture absorption rate. A resin is preferred. By laminating this resin on the first resin layer, it is possible to obtain a metal laminate capable of exhibiting stable characteristics in all atmospheres, particularly with a focus on the reliability of peel strength (adhesion strength). . That is, it is preferable to use a resin having a low humidity expansion coefficient as the second layer resin. Specifically, a resin having a humidity expansion coefficient of 20 ppm or less is preferable, more preferably 15 ppm or less, and even more preferably 13 ppm or less. By forming the second heat-resistant resin layer as a resin layer having a low humidity expansion coefficient, the first resin layer is sandwiched between the metal foil layer and the resin layer having a low humidity expansion coefficient, From the viewpoint of the body structure, the first resin layer is less susceptible to humidity, so it seems to be excellent in heat resistance reliability and moisture resistance reliability, but the mechanism is not clear.
In the second resin layer, when the total amount of the acid component is 100 mol%, the total amount of the amine component is 100 mol%, and the total amount of the acid component and the amine component is 200 mol%, the monomer having a biphenylene group is 100 A mol% or more polyamideimide is preferred. More preferably, 120 mol% or more, and still more preferably 140 mol% or more of polyamideimide is used. If the biphenylene group is less than 100 mol%, the moisture absorption characteristics are deteriorated, and the moisture resistance reliability such as the adhesive strength after the humidification treatment may not be sufficiently satisfied, and the dimensional change rate is also deteriorated. Tend to decrease. The monomer having a biphenylene group is preferably 180 mol% or less, more preferably 170 mol% or less, and most preferably 160 mol% or less. If it exceeds 180 mol%, the solubility tends to decrease.
Moreover, 99 / 1-65 / 35 molar ratio is preferable, and, as for imide bond and amide bond molar ratio, More preferably, it is 90 / 10-70 / 30 molar ratio. If the molar ratio of imide bond to amide bond is less than 65/35, the dimensional accuracy such as the moisture absorption dimensional change rate tends to deteriorate, and the moisture resistance such as peel strength (adhesive strength) after the humidification treatment also tends to deteriorate. . If the molar ratio of the imide bond to the amide bond exceeds 99/1, the solubility tends to be poor, and further, the elastic modulus is increased, and the folding resistance and bending characteristics tend to be deteriorated.
One preferred embodiment of the resin layer of the second layer has a repeating unit consisting of general formula (5), general formula (6), and general formula (7) as a constituent component, and their copolymerization ratio is {general formula (5)} / {General formula (6)} / {General formula (7)} = 30 to 75/10 to 50/10 to 50 (molar ratio) polyamideimide resin is preferable. More preferably, {general formula (5)} / {general formula (6)} / {general formula (7)} = 35 to 65/10 to 30/20 to 50 (molar ratio), most preferably {General formula (5)} / {General formula (6)} / {General formula (7)} = 40-50 / 10-25 / 25-40 (molar ratio). Here, the molar ratio of imide bond to amide bond is preferably 99/1 to 65/35 molar ratio, and more preferably 90/10 to 70/30 molar ratio. When the general formula (5) is more than 75 mol% and the general formula (6) and the general formula (7) are lower than the lower limit, respectively, the dimensional accuracy such as the moisture absorption dimensional change rate is increased, and the peel after the humidification treatment Moisture resistance such as strength (adhesive strength) tends to deteriorate. Further, when the general formula (5) is less than 30 mol% and the general formula (6) and the general formula (7) are more than the upper limit, respectively, the solubility is poor, and the elastic modulus of the resin film is increased, It tends to be difficult to ensure flexibility and folding resistance, which is one of the objects of the present invention. On the other hand, when the molar ratio of imide bond to amide bond is less than 65/35, the dimensional accuracy such as the moisture absorption dimensional change rate is deteriorated, and the moisture resistance such as peel strength (adhesion strength) after the humidification treatment tends to be deteriorated. If the molar ratio of the imide bond to the amide bond exceeds 99/1, the solubility tends to be poor, and further, the elastic modulus is increased, and the folding resistance and bending characteristics tend to be deteriorated.
In particular, among the acid component and the amine component, the most preferable combination is when a monomer having a bisubstituted biphenylene group such as dimethyldiaminobiphenyl is used, and the acid component is trimellitic anhydride, 3, 3 ′, 4,4′-benzophenonetetracarboxylic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and the amine component is 3,3′-dimethyl- This is the case for 4,4′-diaminobiphenyl (or the corresponding diisocyanate).
According to IPC-FC241 (IPC-TM-650, 2.4.9 (A)), using a sample in which a circuit pattern was created by a subtractive method, heating at 85 ° C., 85% RH, under humidification for 500 hours In order to further increase the adhesive strength after the treatment, it is preferable to increase the ratio of imide bonds to amide bonds in the second-layer resin and to perform appropriate molecular design in consideration of the above matters.

  Here, in general formula (7), Y is preferably a direct bond (biphenyl bond) or an ether bond, and in particular, from dimensional accuracy (low moisture absorption dimensionality) and moisture resistance (peel stability after humidification treatment, etc.) More preferably, it is a direct bond (biphenyl bond). In addition, each of the units represented by the following general formula (7) may be one type or two or more types.

  Further, these polyamide-imide resins are preferably non-halogen-based resins that do not contain halogens such as fluorine, chlorine, bromine and iodine from the viewpoint of environmental considerations.

The imidization rate of these polyamide-imide resins is preferably 50% or more, more preferably 90% or more, and still more preferably 95% or more. The higher the imidization rate, the more preferable the upper limit is 100%. When the imidization ratio of the imide bond is less than 50%, the adhesiveness with the resin film of the first layer is lowered, and as a result, peeling between the resin layers tends to occur, and after the soldering process or the humidification process Later, the peel strength (adhesive strength) tends to decrease. As a result, reliability such as folding resistance, flexibility, heat resistance reliability, moisture resistance reliability (peel strength), and the like may be poor.
The reason for this is that if a molding process such as heat treatment is performed in a laminated structure before the imidization reaction of the second layer is completed, the imidization reaction proceeds with the heat treatment, and the condensation that occurs along with that proceeds. It is estimated that water adversely affects the adhesiveness at the resin layer or at the interface between the resin and the metal foil. Therefore, the production of the resin composition used in the present application is a method such as the isocyanate method described later, in which the imidation ratio of the obtained resin varnish is completed after polymerization even in the second layer resin composition. It is preferable to manufacture by. Since it is essential to dissolve in a polymerization solvent, the composition is preferably soluble in an organic solvent. In addition, it is desirable to pay attention to the production conditions since the imidization reaction may not always be completed after the polymerization due to the purity of the monomer and the influence of the solvent type even in the production by the isocyanate method.
In order to make the imidization ratio 50% or more, an example is shown. In the case of the amine method, a precursor is synthesized by a usual method, and after film formation, the temperature is gradually raised to Tg or more, and around Tg (plus It is desirable to carry out sufficient imidization treatment by heating at minus 10 ° C. for about 1 hour. In the isocyanate method, it is preferable to increase the moisture content to 50 mol% or less of the number of moles of the monomer or to increase the purity of the monomer in the polymerization. For example, use of a trimellitic anhydride having a high cyclization rate, It is desirable that the monomer purity is high, such as a small amount of diamine as an impurity.
In addition, the measurement of imidation rate can be calculated | required by the method as described in the below-mentioned Example.

  It is preferable that the polyamide-imide resin can be dissolved in an organic solvent from the viewpoint of processability when a flexible metal-clad laminate or a laminated film with an adhesive layer described later is used. The organic solvents mentioned here are N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, tetramethylurea, sulfolane, dimethyl. It is at least one selected from the group consisting of sulfooxide, γ-butyrolactone, cyclohexanone and cyclopentanone, or a part of these is a group consisting of toluene, xylene, diglyme, triglyme, tetrahydrofuran, methyl ethyl ketone and methyl isobutyl ketone. It shall be replaced with at least one selected from the above. In the present invention, being soluble in an organic solvent means that any one of the above-mentioned single solvents or a mixed organic solvent containing 20% or more of at least one of them is 10% by weight or more. It is preferable to dissolve. More preferably, it is 15 weight% or more, More preferably, it is 20 weight% or more. In addition, when the resin is in a solid state, whether or not it has been dissolved is determined by adding a specified weight of resin powder passing through 80 mesh into a 200 ml beaker and gently stirring at 25 ° C. for 24 hours. It was determined that it was dissolved at 25 ° C. for 24 hours, and the solution that was not gelled, non-uniformized, clouded, or precipitated was dissolved.

To be soluble in a solvent,
(1) The above-mentioned preferred resin composition is used, (2) the ratio of imide group / amide group is lowered, (3) copolymerization as a polycarboxylic acid component and polyamine component having an alicyclic group described later, (4 ) Copolymerized as a polycarboxylic acid component having an aliphatic group, which will be described later, and a polyamine component. (5) A flexible group is introduced into the aromatic ring. (6) A bulky compound is introduced into the polymer chain. (7) The polymer is modified with an epoxy compound described later.
Etc. can be achieved.

(In the formula, R5 and R6 may be the same or different and each represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group.)

(In the formula, R 3 and R 4 may be the same or different and each represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group.)

(In the formula, R1 and R2 may be the same or different and each represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group. Y is a direct bond (biphenyl bond), or Indicates an ether bond (—O—).)

According to IPC-FC241 (IPC-TM-650, 2.4.9 (A)), using a sample in which a circuit pattern was created by a subtractive method, heating at 85 ° C., 85% RH, under humidification for 500 hours An example of a preferred embodiment of the second resin layer for increasing the adhesive strength after treatment to a desired value or more is shown above, but is not limited to the above, and is not limited to methyl group, ethyl group, fluorine It is only necessary to reduce the water absorption rate of the resin itself by introducing a hydrophobic substituent such as a system group or lowering the polarity of the bond, thereby improving the adhesive strength even in a moisture-resistant environment. it can. In order to reduce the polarity of the bond, for example, there are means such as increasing the ratio of the imide bond to the amide bond, and by performing the appropriate molecular design as described above, the adhesive strength after the desired warming and humidification A resin having is obtained.

[Production of polyamide-imide resin]
The polyamideimide resin can be synthesized by a usual method. For example, the isocyanate method, amine method (acid chloride method, low temperature solution polymerization method, room temperature solution polymerization method, etc.), etc., but the polyamideimide resin used in the present invention is preferably soluble in an organic solvent. For reasons such as ensuring the reliability of strength (adhesive strength), production by the isocyanate method is preferred. Also, industrially, it is preferable because the solution at the time of polymerization can be applied as it is.

  In the case of the isocyanate method, as a raw material, aromatic tricarboxylic acid anhydride, aromatic dicarboxylic acid, aromatic tetracarboxylic dianhydride and the like and aromatic diisocyanate are reacted in an organic solvent in an approximately stoichiometric amount in the present invention. A resin composition can be obtained. Here, trimellitic anhydride is used as the aromatic tricarboxylic acid anhydride, and pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride is used as the aromatic tetracarboxylic acid anhydride. Products, diphenyl ether-3,3 ′, 4,4′-tetracarboxylic acid, etc., and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, biphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylsulfone dicarboxylic acid, etc. 1,4-naphthalene diisocyanate, 1,5-naphthalene diisocyanate, 2,6-naphthalene diisocyanate, 2,7-naphthalene diisocyanate, orthotolidine diisocyanate and the like can be used.

  The reaction is preferably carried out in an organic solvent usually at 10 ° C. to 200 ° C. for 1 hour to 24 hours, and the reaction is a catalyst for the reaction of an isocyanate and an active hydrogen compound, for example, tertiary amines, alkali metal compounds, alkaline earth metals You may carry out in presence of a compound etc.

  As a polymerization solvent for producing the polyamideimide resin of the present invention, an organic solvent capable of dissolving the polyamideimide resin can be used. Typical examples of such organic solvents include, for example, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, tetramethylurea, sulfolane. Dimethyl sulfoxide, γ-butyrolactone, cyclohexanone, cyclopentanone, etc., preferably N-methyl-2-pyrrolidone. Some of these can be replaced with hydrocarbon organic solvents such as toluene and xylene, ether organic solvents such as diglyme, triglyme and tetrahydrofuran, and ketone organic solvents such as methyl ethyl ketone and methyl isobutyl ketone.

  The molecular weight of the polyamideimide resin of the present invention is the molecular weight corresponding to 0.3 to 2.5 dl / g in N-methyl-2-pyrrolidone (polymer concentration 0.5 g / dl) and logarithmic viscosity at 30 ° C. Those having a molecular weight corresponding to 0.5 to 2.0 dl / g are more preferable. If the logarithmic viscosity is less than 0.3 dl / g, mechanical properties may be insufficient when formed into a molded product such as a film, and if it exceeds 2.0 dl / g, the solution viscosity becomes high, so that molding processing is performed. May be difficult.

The polyamide-imide resin of the present invention has the target characteristics of the present invention for the purpose of balancing various performances such as heat resistance, adhesiveness, dimensional stability, flexibility, insulation (migration resistance), and moisture resistance. It is possible to copolymerize the acid component and amine component shown below in addition to the acid component, isocyanate component, or amine component shown above as long as they are not impaired. Also, a resin separately polymerized by a combination of these acid component and amine component can be mixed and used. Of course, the above-mentioned acid component and the resin component separately polymerized in combination with the amine component may be mixed together. In addition to the above-mentioned acid component, in addition to the acid component described below and the above-described amine component, A resin polymerized separately in combination with the amine component described in 1) may be mixed.

Examples of the acid component include the following.
a) Tricarboxylic acid; diphenyl ether-3,3 ′, 4′-tricarboxylic acid, diphenylsulfone-3,3 ′, 4′-tricarboxylic acid, benzophenone-3,3 ′, 4′-tricarboxylic acid, naphthalene-1,2 , 4-tricarboxylic acid, monoanhydrides such as tricarboxylic acid such as butane-1,2,4-tricarboxylic acid, esterified compounds, or a mixture of two or more.
b) Tetracarboxylic acid; diphenylsulfone-3,3 ′, 4,4′-tetracarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, naphthalene-1,2,4,5-tetracarboxylic acid , Naphthalene-1,4,5,8-tetracarboxylic acid, butane-1,2,3,4-tetracarboxylic acid, cyclopentane-1,2,3,4-tetracarboxylic acid monoanhydride, dianhydride , Esterified products alone or a mixture of two or more.
c) Dicarboxylic acid; adipic acid, azelaic acid, sebacic acid, dicarboxylic acid of cyclohexane-4,4′-dicarboxylic acid, and monoanhydrides and esterified products thereof.

For example, the following are mentioned as an amine component.
d) Amine component 3,3′-dimethyl-4,4′-diaminobiphenyl, 3,3′-diethyl-4,4′-diaminobiphenyl, 2,2′-dimethyl-4,4′-diaminobiphenyl, 2 , 2′-diethyl-4,4′-diaminobiphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-diethoxy-4,4′-diaminobiphenyl, p-phenylenediamine, m -Phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminobiphenyl, 3,3 ' -Diaminobiphenyl, 3,3'-diaminobenzanilide, 4,4'-diaminobenzanilide, 4,4'-diaminobenzophenone, 3,3'-diamy Nobenzophenone, 3,4'-diaminobenzophenone, 2,6-tolylenediamine, 2,4-tolylenediamine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4 ' -Diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, p-xylenediamine, m-xylenediamine, 2,2'-bis (4-amino) Phenyl) propane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,2-bis [4 -(4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone, [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] propane, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3 -Aminophenoxy) biphenyl, tetramethylenediamine, hexamethylenediamine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, cyclohexane-1,4-diamine, diaminosiloxane, or the corresponding diisocyanate alone or in two kinds The above mixture is mentioned. Of course, the monomer component used in the first layer can be used in a part of the second layer, and vice versa.

[Polyamideimide resin solution]
If necessary, for the purpose of improving various properties of the flexible metal-clad laminate or flexible printed circuit board, for example, mechanical properties, electrical properties, slipperiness, flame retardancy, etc., the polyamideimide resin solution of the present invention is used. In addition, other resins, organic compounds, and inorganic compounds may be mixed or reacted to be used in combination. For example, lubricant (silica, talc, silicone, etc.), adhesion promoter, flame retardant (phosphorus, triazine, aluminum hydroxide, etc.), stabilizer (antioxidant, UV absorber, polymerization inhibitor, etc.), plating activity Agents, organic and inorganic fillers (talc, titanium oxide, silica, fluorine polymer fine particles, pigments, dyes, calcium carbide, etc.), silicone compounds, fluorine compounds, isocyanate compounds, blocked isocyanate compounds, acrylic resins, urethanes Resin, polyester resin, polyamide resin, epoxy resin, phenolic resin and organic compounds, or these curing agents, silicon oxide, titanium oxide, calcium carbonate, iron oxide and other inorganic compounds do not hinder the purpose of this invention Can be used together in a range. In addition, if necessary, a catalyst for polyimide formation such as aliphatic tertiary amine, aromatic tertiary amine, heterocyclic tertiary amine, aliphatic acid anhydride, aromatic acid anhydride, hydroxy compound, etc. It may be added. For example, triethylamine, triethylenediamine, dimethylaniline, pyridine, picoline, isoquinoline, imidazole, undecene, hydroxyacetophenone and the like are preferable, and pyridine compound, imidazole compound and undecene compound are particularly preferable. Among them, benzimidazole, triazole, 4 -Pyridinemethanol, 2-hydroxypyridine and diazabicyclo [5.4.0] undecene-7 are preferred, and 2-hydroxypyridine and diazabicyclo [5.4.0] undecene-7 are more preferred.

  The concentration of the polyamideimide resin in the polyamideimide resin solution thus obtained can be selected from a wide range, but is generally preferably about 5 to 40% by weight, more preferably about 8 to 20% by weight. When the concentration is out of the above range, the coatability tends to be lowered. Preferred solvents for the polyamide-imide resin solution include N, N-dimethylformamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, tetramethylurea, sulfolane, and dimethylsulfo because of coating properties and the like. Among them, oxide, γ-butyrolactone, cyclohexanone, cyclopentanone, etc., particularly preferably N-methyl-2-pyrrolidone. Some of these can be replaced with hydrocarbon organic solvents such as toluene and xylene, ether organic solvents such as diglyme, triglyme and tetrahydrofuran, and ketone organic solvents such as methyl ethyl ketone and methyl isobutyl ketone. In addition, since these solvents can also be applied as solvents during polymerization, the polymerization solution can be applied as it is, so that a resin solution having excellent processability can be easily obtained.

  As an appropriate solution viscosity, the B-type viscosity at 25 ° C. is preferably in the range of 1 to 1000 poise. When the viscosity is out of the above range, the coatability may be lowered.

[Metal foil]
A flexible metal-clad laminate can be obtained by laminating with a metal foil using the polyamideimide resin or the resin composition. As the metal foil used in the present invention, copper foil, aluminum foil, steel foil, nickel foil, and the like can be used. Composite metal foil obtained by combining these, and metal foil treated with other metals such as zinc and chromium compounds Can also be used. Of these, copper foil is generally used.
Although there is no limitation in particular about the thickness of metal foil, For example, metal foil of 3-50 micrometers can be used suitably. In particular, for finer circuit pitches, the thickness is preferably 3 to 12 μm, and the surface roughness Rz of the coated surface is preferably in the range of 0.5 to 2.0 μm. If each copper foil characteristic is lower than the lower limit, the peel strength (adhesive strength) is low, and if it is higher than the upper limit, it tends to be difficult to make a fine pitch.
The metal foil is usually in the form of a ribbon, and its length is not particularly limited. Also, the width of the ribbon-like metal foil is not particularly limited, but is generally about 25 to 300 cm, particularly about 50 to 150 cm.
As the copper foil, a commercially available electrolytic foil or a rolled foil can be used as it is. For example, “HLS” manufactured by Nippon Electrolytic Co., Ltd., “F0-WS”, “U-WZ” manufactured by Furukawa Circuit Foil Co., Ltd., “NA-VLP”, “DFF” manufactured by Mitsui Mining & Smelting Co., Ltd. Be mentioned

[Method for producing flexible metal laminate]
In the present invention, one preferred production method is to sequentially apply a solution of the two types of polyamideimide resins (first layer resin, second layer resin) to the metal foil directly or via an adhesive layer. It is formed by applying, drying the coating film (hereinafter referred to as initial drying), and optionally heat treatment and solvent removal (hereinafter referred to as secondary drying).

  As a method of laminating two kinds of resins on the metal foil, the first layer can be applied, and after the initial drying, the second layer can be applied and initially dried, and in some cases, it can be produced by secondary drying. Alternatively, the first layer may be applied, initially dried and secondarily dried, and then the second layer may be applied, initially dried and secondarily dried. Furthermore, after the first layer is applied, the second layer may be applied, and initial drying and secondary drying may be performed. In this case, the first layer and the second layer can be applied simultaneously.

(Coating)
In the present invention, the polyamideimide resin solution is applied directly to the metal foil or via an adhesive layer and dried. The application method is not particularly limited, and a conventionally well-known method can be applied. For example, after adjusting the viscosity of the polyamide-imide resin solution, which is the coating solution, using a roll coater, knife coater, doctor, blade coater, gravure coater, die coater, reverse coater, etc., either directly on the metal foil or with an adhesive layer Can be applied. The adhesive composition when applied through the adhesive layer is not particularly limited, and acrylonitrile butadiene rubber (NBR) adhesive, polyamide adhesive, polyester adhesive, polyester urethane adhesive, epoxy resin Type, acrylic resin type, polyimide resin type, polyamideimide resin type, polyesterimide resin type and other adhesives can be used, but in terms of heat resistance, adhesiveness, bending resistance, etc., polyimide resin type, polyamideimide resin type, or A resin composition in which an epoxy resin is blended with these resins is preferable, and the thickness of the adhesive layer is preferably about 5 to 30 μm.
In addition, for the purpose of improving various properties of the flexible printed circuit board, the polyamideimide resin solution, which is the coating liquid of the present invention, is applied directly to the metal foil or through the adhesive layer, or after application / drying, It is also possible to further apply an adhesive. The adhesive composition and thickness are the same as described above from the viewpoints of heat resistance, adhesion, bending resistance, curling properties of the flexible printed wiring board, and the conditions for coating and drying are the same as those of the polyamideimide resin solution of the present invention. The same conditions can be applied.

(Dry)
In the present invention, there is no particular limitation on the drying conditions after coating, but generally, after initial drying at a temperature 70 ° C. to 130 ° C. lower than the boiling point (Tb (° C.)) of the solvent used in the polyamideimide resin solution, It is preferable to further dry (secondary drying) at a temperature near the boiling point of the solvent or at a temperature higher than the boiling point.

  When the initial drying temperature is higher than (Tb-70) ° C., foaming occurs on the coated surface, and unevenness of the residual solvent in the thickness direction of the resin layer increases, so that the flexible metal laminate is warped (curl). In some cases, the warp of the flexible printed circuit board obtained by processing the circuit may be increased.

  Moreover, when drying temperature is lower than (Tb-130) degreeC, drying time will become long and productivity will fall. The initial drying temperature varies depending on the type of solvent, but is generally about 60 to 150 ° C, preferably about 80 to 120 ° C. The time required for the initial drying is generally an effective time for the solvent remaining rate in the coating film to be about 5 to 40% under the above temperature conditions, but generally about 1 to 30 minutes, especially 2 About 15 minutes is preferable.

  The secondary drying conditions are not particularly limited, and may be dried near the boiling point of the solvent or at a temperature equal to or higher than the boiling point. Generally, the drying temperature is preferably 120 ° C to 400 ° C, more preferably 200 ° C to 300 ° C. . If it is less than 120 degreeC, drying time will become long and productivity will fall, and if it exceeds 300 degreeC, a deterioration reaction may advance depending on resin composition, and a resin film may become brittle. The time required for the secondary drying may be an effective time that generally eliminates the solvent remaining rate in the coating film under the above temperature conditions, but is generally about several minutes to several tens of hours.

In the present invention, drying may be performed under an inert gas atmosphere or under reduced pressure. Examples of the inert gas include nitrogen, carbon dioxide, helium, and argon, but it is preferable to use easily available nitrogen. Moreover, when performing under reduced pressure, it is preferable to carry out under the pressure of about 10 < ^-5 > -10 < ³ > Pa, preferably about 10 < ^-1 > -200 Pa.

  In the present invention, there are no particular limitations on the drying method for both initial drying and secondary drying, but it can be performed by a conventionally known method such as a roll support method or a floating method. Further, continuous heat treatment in a heating furnace such as a tenter type, winding in a wound state, and heat treatment in a batch type oven may be performed. In the case of a batch type, it is preferable to wind up so that a coating surface and a non-coating surface do not contact. As a heating method, a conventionally known electric furnace, IR heater, far infrared heater, or the like can be applied.

  Moreover, the thermoplastic polyamideimide solution of the first layer in the present invention is applied to one side or both sides of a heat-resistant film such as polyimide film, polyamide film, polyamideimide film, etc. prepared in advance, and the same processing method as above The flexible metal laminate of the present invention can also be produced by obtaining a multilayer heat-resistant film and thermally bonding a metal foil to the surface of the thermoplastic polyamideimide layer. As a method of thermocompression bonding, a conventionally known method can be applied, and it can be manufactured by heating roll lamination, heating press lamination, or the like.

  In the present invention, the ratio (T1) / (T2) between the thickness (T1) of the first resin layer and the thickness (T2) of the second resin layer is preferably 0.05 to 5, more preferably. Is 0.1-5, and still more preferably 0.15-5. If (T1) / (T2) is less than 0.05, the flexibility, folding resistance, and heat resistance reliability tend to be inferior. If it exceeds 5, dimensional stability, peel strength after humidification (adhesion strength), etc. It tends to be inferior in moisture resistance reliability.

  The flexible metal-clad laminate of the present invention thus obtained is characterized by being excellent in heat resistance, dimensional stability, and adhesiveness because it has a metal foil directly on at least one surface of the polyamideimide resin film layer. In addition, imidization process is not required and molding is possible only by drying solvent, or because heat treatment at high temperature is unnecessary, it can be manufactured at low cost and has excellent moisture resistance, flexibility, bendability and moisture absorption characteristics. It is characterized by that.

The thickness of the first resin layer is preferably 3 to 50 μm, more preferably 5 to 30 μm, and most preferably 7 to 20 μm. If it is less than 3 μm, the adhesive strength after heating and humidity, the adhesive strength after soldering, flexibility, and folding resistance tend to be lowered. If it exceeds 50 μm, the dimensional change rate of moisture absorption tends to increase.
The thickness of the second resin layer is preferably 10 to 60 μm, more preferably 20 to 50 μm, and most preferably 25 to 40 μm. If it is less than 10 μm, the hygroscopic dimensional change rate tends to increase. If it exceeds 60 μm, the flexibility and folding resistance tend to be lowered.
In the flexible metal-clad laminate of the present invention consisting of a heat-resistant resin film and a metal foil, when the heat-resistant resin film is made of a polyamideimide resin, the thickness of the polyamideimide resin film layer can be selected from a wide range. Generally, the thickness after absolutely dry is about 5 to 100 μm, preferably about 10 to 50 μm. When the thickness is less than 5 μm, the mechanical properties such as film strength and handling properties are inferior. On the other hand, when the thickness exceeds 100 μm, the properties such as flexibility and workability (drying property, coating property) are deteriorated. Tend to. In addition, the flexible metal-clad laminate of the present invention may be subjected to a surface treatment as necessary. For example, surface treatment such as hydrolysis, low-temperature plasma, physical roughening, and easy adhesion coating treatment can be performed.

The double-sided flexible metal laminate of the present invention is a metal laminate having metal foils on both sides. For example, the resin surfaces of a metal laminate in which metal foils are laminated only on one side produced as described above are heated. It can be produced by a conventionally known method such as laminating or by a conventionally known method through an adhesive layer.
Moreover, the thermoplastic polyamideimide solution of the first layer in the present invention is formed on one side or both sides of a heat-resistant film (second layer resin layer) such as a polyimide film, a polyamide film, or a polyamideimide film prepared in advance. It is also possible to obtain a multilayer heat-resistant film by the same processing method as described above, and to thermally bond the metal foil to the surface of the thermoplastic polyamideimide layer to obtain a double-sided flexible gold laminate. As a method of thermocompression bonding, a conventionally known method can be applied, and it can be manufactured by heating roll lamination, heating press lamination, or the like.
The laminating method is not particularly limited, and a conventionally known method such as roll laminating, press laminating, belt press laminating, etc. can be adopted, and the laminating temperature is usually Tg of the resin or more, for example, the resin layer on the bonding surface Of 300 ° C. to 500 ° C., more preferably 350 ° C. to 450 ° C., and still more preferably 380 ° C. to 430 ° C. If it is less than 300 ° C., the adhesiveness is insufficient, and if it exceeds 500 ° C., the resin is deteriorated and the mechanical properties tend to be lowered. The laminating time is not particularly limited, but is usually 10 seconds to 10 hours, preferably 1 minute to 1 hour, more preferably 3 minutes to 30 minutes. If it is less than 10 seconds, the adhesiveness is insufficient, and if it exceeds 10 hours, the resin layer is deteriorated and the mechanical properties tend to be lowered.
The adhesive composition in the case of bonding through the adhesive layer is not particularly limited, and acrylonitrile butadiene rubber (NBR) adhesive, polyamide adhesive, polyester adhesive, polyester urethane adhesive, epoxy resin Type, acrylic resin type, polyimide resin type, polyamideimide resin type, polyesterimide resin type and other adhesives can be used, but in terms of heat resistance, adhesiveness, bending resistance, etc., polyimide resin type, polyamideimide resin type, or A resin composition in which an epoxy resin is blended with these resins is preferable, and the thickness of the adhesive layer is preferably about 5 to 30 μm. From the viewpoint of insulation performance, polyester or polyester urethane resin, or a resin composition in which an epoxy resin is blended with these resins is preferable, and the thickness of the adhesive layer is preferably about 5 to 30 μm. The thickness of the adhesive is not particularly limited as long as it does not hinder the performance of the flexible printed circuit board, but if the thickness is too thin, sufficient adhesiveness may not be obtained. If the thickness is too thick, processability (drying property, coating property) and the like may be deteriorated. As a means for forming a laminated structure through the adhesive layer, a heat-resistant film molded using the heat-resistant resin of the present invention described later and a metal foil are bonded together by the above-mentioned adhesive by a method such as heat lamination. You can also

[Flexible printed circuit board]
Using the flexible metal-clad laminate of the present invention, a flexible printed board can be produced by a method such as a subtractive method. When the circuit surface is coated for the purpose of protecting the solder resist of the conductor circuit or from dirt and scratches, a heat-resistant film such as polyimide is bonded to the wiring board (the conductor circuit is formed by an adhesive) by a conventionally known method. A method of bonding to a formed base substrate) or a method of applying a liquid coating agent to a wiring board by a screen printing method can be applied. As the liquid coating agent, conventionally known epoxy-based and polyimide-based inks can be used, but polyimide-based inks are preferable. It is also possible to directly bond an epoxy or polyimide adhesive sheet to the wiring board. The flexible printed circuit board thus obtained has excellent heat resistance reliability, dimensional stability and adhesiveness, and also has excellent moisture resistance reliability, folding resistance properties, flexibility, moisture absorption properties, and insulation properties. For example, a fine pitch is required. Since it can be used with a circuit board, a COF substrate, or the like, there are significant industrial advantages.

(Method for manufacturing flexible printed circuit board)
The flexible printed circuit board of the present invention can be manufactured using a conventionally known process except that the material of each layer described above is used.
In one preferred embodiment, a cover film with an adhesive is produced by laminating an adhesive layer on a polyimide film. On the other hand, a semi-finished product in which a desired circuit pattern is formed on the base film layer (hereinafter referred to as “base film-side semi-finished product”) is manufactured. A flexible printed wiring board can be obtained by bonding the cover film with adhesive and the base film side semi-finished product thus obtained.

(Manufacturing method of base film side semi-finished product)
A base film side semi-finished product is manufactured by forming a circuit in a metal foil layer using the above-mentioned flexible metal-clad laminate. A conventionally known method can be used to form the circuit. An additive method may be used and a subtractive method may be used. The subtractive method is preferable.
An arbitrary pattern can be formed as the circuit wiring pattern. In particular, the flexible printed circuit board of the present invention exhibits a high level of performance even in a circuit having a fine wiring pattern, and therefore the flexible printed circuit board of the present invention is particularly advantageous in a circuit having a fine wiring pattern.

Specifically, the wiring thickness of the circuit can be 100 μm or less, the wiring thickness can be 50 μm or less, and the wiring thickness can be 30 μm or less. It is also possible to make the thickness of the wiring 10 μm or less.
The interval between the wirings can be 100 μm or less, can be 50 μm or less, can be 30 μm or less, and can be 10 μm or less. The sum of the thickness of the wiring and the wiring interval (circuit pitch) can be 100 μm or less, can be 60 μm or less, and can also be 20 μm or less.

(Manufacturing method of cover film with adhesive)
The cover film with an adhesive is manufactured, for example, by applying an adhesive to a polyimide film and drying it. The adhesive is not particularly limited, and acrylonitrile butadiene rubber (NBR) adhesive, polyamide adhesive, polyester adhesive, polyester urethane adhesive, epoxy resin, acrylic resin, polyimide resin, polyamideimide Resin-based and polyesterimide resin-based adhesives can be used, but from the viewpoint of heat resistance, adhesiveness, bending resistance, etc., polyimide resin-based, polyamide-imide resin-based, or a resin composition in which an epoxy resin is blended with these resins Is preferred. As a method of laminating the adhesive, a general method can be applied, and there is no particular limitation. For example, a coating method such as a roll coater, a knife coater, a doctor, a blade coater, a gravure coater, a die coater, and a reverse coater is used. It can be applied to an insulating film, dried and laminated. In some cases, it is possible to form an adhesive layer on the releasable film by the above application method, and to laminate the adhesive layer on the insulating film by a transfer method. Drying conditions are set as appropriate according to the adhesive used. Usually, it is about 30 to 150 ° C. If necessary, a crosslinking reaction can be performed in the applied adhesive. In a preferred embodiment, the adhesive layer is semi-cured.

  The obtained cover film with adhesive may be used as it is for pasting with the base material-side semi-finished product, and after sticking and storing the release film, it is pasted with the base film-side semi-finished product. They may be used together.

(Lamination of base film side semi-finished product and cover film with adhesive)
Any method can be used as a method of bonding the base film side semi-finished product and the cover film with adhesive. For example, it can bond together using a press or a roll. Moreover, both can also be bonded together, heating by the method of using a heating press or a heating roll press apparatus.

  For example, if the adhesive layer in the semi-finished product is in an uncured or semi-cured state, it can be cured by proceeding with the crosslinking reaction of the adhesive layer by heating at the time of bonding. It is also possible to easily obtain a final product in which the agent layer is completely cured. When the crosslinking reaction is insufficient, or when it is necessary to precisely control the crosslinking reaction, post-curing can be performed as necessary after pasting by any of the above methods.

[How to use flexible printed circuit board]
The flexible printed circuit board of the present invention can have any laminated structure that can be employed as a flexible printed circuit board. For example, as above-mentioned, it can be set as the flexible printed circuit board comprised from four layers, a base film layer, a metal foil layer, an adhesive bond layer, and a cover film layer.

  Further, if necessary, a configuration in which two or three or more of the above-mentioned flexible printed boards are laminated may be employed. For example, it is possible to laminate a plurality of the above-mentioned four-layer type flexible printed boards and bond the flexible printed board and the flexible printed board with an adhesive as necessary. More specifically, for example, the base film layer of the first flexible printed circuit board, the metal foil layer of the first flexible printed circuit board, the adhesive layer of the first flexible printed circuit board, and the cover of the first flexible printed circuit board A film layer; an adhesive layer that bonds the first flexible printed circuit board and the second flexible printed circuit board; a base film layer of the second flexible printed circuit board; a metal foil layer of the second flexible printed circuit board; A total of nine layers of the adhesive layer of the flexible printed circuit board and the cover film layer of the second flexible printed circuit board can be sequentially laminated.

In addition, for example, the four-layer type flexible printed circuit board can be formed in such a manner that the bottoms of two base film films are bonded to each other by an adhesive layer and bonded back to back. In this case, for example, if the 4-layer type flexible printed circuit board is used,
A cover film layer of a first flexible printed circuit board;
An adhesive layer of the first flexible printed circuit board;
A metal foil layer of the first flexible printed circuit board;
A base film layer of a first flexible printed circuit board;
An adhesive that bonds the base films of the first flexible printed circuit board and the second flexible printed circuit board;
A base film layer of a second flexible printed circuit board;
The metal foil layer of the second flexible printed circuit board A total of 9 layers of the adhesive layer of the second flexible printed circuit board and the cover film layer of the second flexible printed circuit board may be laminated in order.

[Applications of flexible printed circuit boards]
The flexible printed circuit board of the present invention can be used for various products for which a flexible printed circuit board has been conventionally used. In particular, the flexible printed circuit board of the present invention is excellent in heat resistance, dimensional stability, moisture resistance, flexibility, folding resistance, insulation, and the like. Can be suitably used for applications that require a narrower interval. For example, it is suitable for products whose wiring thickness is 30 μm or less. Further, for example, it is suitable for a product having a wiring interval of 60 μm or less, more suitable for a product having a wiring interval of 30 μm or less, and further suitable for a product having a wiring interval of 10 μm or less. Therefore, it can be suitably used for applications in which the sum (circuit pitch) of the wiring thickness and the wiring interval is narrow. It is suitable for products having a circuit pitch of 100 μm or less, more suitable for products having a circuit pitch of 60 μm or less, more suitable for products having a circuit pitch of 30 μm or less, and particularly suitable for products having a circuit pitch of 20 μm or less.

  Examples of specific final products in which the flexible printed circuit board of the present invention is used include flat panel displays, drive modules for liquid crystal monitors such as mobile phones, and the like.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not particularly limited by the examples.
[Production example of flexible metal laminate]
The evaluation method of the characteristic value in each example is as follows. The powdered polyamideimide resin sample used for evaluation was prepared by reprecipitation and purification of the polymer dope obtained in each synthesis example with a large amount of acetone. Moreover, the resin film (base film) used for various measurements and evaluations is obtained by using 35% ferric chloride as the metal foil of the flexible metal-clad laminate obtained in each Example and Comparative Example unless otherwise specified. It was obtained by etching away at (40 ° C.).

<Logarithmic viscosity>
Using a powdered polymer sample, it was dissolved in N-methyl-2-pyrrolidone so that the polymer concentration was 0.5 g / dl. The solution viscosity of the solution and the solvent viscosity were 30 ° C., and an Ubbelohde viscosity. It measured with the pipe | tube and it calculated by the following formula.
Logarithmic viscosity (dl / g) = [ln (V1 / V2)] / V3

  In the above formula, V1 represents the solution viscosity measured with an Ubbelohde type viscosity tube, V2 represents the solvent viscosity measured with an Ubbelohde type viscosity tube, and V1 and V2 represent a polymer solution and a solvent (N-methyl-2-pyrrolidone). Was determined from the time taken to pass through the capillary of the viscosity tube. V3 is the polymer concentration (g / dl).

<Tg>
The polyamideimide resin sample shown in Table 1 was applied to a metal foil and dried, and then the metal foil was etched away with 35% ferric chloride (40 ° C.) to obtain a single-layer resin film. Using this resin film (sample size 4 mm width × 15 mm length) with a dynamic viscoelasticity measuring device (Leobibron manufactured by Orientec Co., Ltd.) under the conditions of a frequency of 1 Hz and a heating rate of 10 ° C./min, from the peak top of Tan δ Tg was determined.

<Dimensional change rate>
About the resin film obtained by etching and removing the metal foil in the sample of the example, in the MD direction under the condition of 150 ° C. × 30 minutes by IPC-FC241 (IPC-TM-650, 2.2.4 (c)) Measurement was performed in the TD direction, and an average value was obtained.

<Adhesive strength after soldering>
A circuit pattern was prepared from the sample of the example according to IPC-FC241 (IPC-TM-650, 2.4.9 (A)) by a subtractive method, and the sample was floated in a solder bath at 350 ° C. for 30 seconds. Using the sample, the adhesive strength was measured. The sample was floated on the solder bath in such a manner that the resin base material surface was in contact.

<Adhesive strength after heating and humidifying for 500 hours>
According to IPC-FC241 (IPC-TM-650, 2.4.9 (A)), the circuit pattern was created by the subtractive method, and the sample after being treated at 85 ° C. and 85% RH for 500 hours. Using, the adhesive strength of a circuit pattern and a heat resistant resin film was measured.

<Humidity expansion coefficient>
After the polyamideimide resin sample shown in Table 1 was coated on a metal foil and dried, a metal-clad laminate was prepared.
It measured by the following.
(1) A hole is made in a certain position of the metal-clad laminate according to IPC-FC 241 (IPC-TM-650, 2.2.4 (c)), and humidity is adjusted at 25 ° C. and 65% for 4 hours. Measure the distance between holes.
(2) The front surface of the metal layer of the metal-clad laminate was removed with ferric chloride (etching), and the resulting resin film was subjected to 25% relative humidity in an atmosphere of 20%, 40%, 65%, and 90%. Condition at 24 ° C for 24 hours.
(3) According to IPC-FC 241 (IPC-TM-650, 2.2.4 (c)), the distance between holes in the resin film is measured, and the distance between holes in the metal foil laminate in (1). The dimensional change rate is obtained based on the above.
(4) The rate of dimensional change in (3) was plotted against each relative humidity, and the slope with respect to that humidity was defined as the humidity expansion coefficient (CHE).

<Folding resistance>
In the sample of the example, a resin film (sample size; 25.4 mm × 88.9 mm) obtained by etching and removing the metal foil was JIS L using a Gurley type flexibility tester manufactured by Toyo Seiki Seisakusho. According to 1096, the degree of flexibility (a measure of repulsive force) was measured. The determination of the measurement result was evaluated as “x” when the value of the flexibility was 120 mg or more and “◯” when it was lower than 120 mg.

<Strength, elongation and elastic modulus of resin film>
The polyamideimide resin sample shown in Table 1 was applied to a metal foil and dried, and then the metal foil was etched away with 35% ferric chloride (40 ° C.) to obtain a single-layer resin film. A sample having a width of 10 mm and a length of 100 mm was prepared from this resin film, and measured with a tensile tester (trade name “Tensilon tensile tester”, manufactured by Toyo Baldwin) at a tensile speed of 20 mm / min and a distance between chucks of 40 mm. did.

<Imidization rate>
Using a powdery polymer sample, the absorbance ratio is determined from absorption of imide (1380 cm-1) and absorption of benzene gap (1510 cm-1) by the infrared spectrophotometer (manufactured by Shimadzu Corporation) KBr method. It was.
The calculation of the imidization ratio was carried out in the same manner using a powder sample prepared by scraping the resin surface of a metal laminated film prepared from the varnish of the same resin composition under the following conditions. ) And the benzene nucleus (1510 cm −1), and the absorbance ratio was calculated as 100%.
―Metal laminated film making method―
Using a knife coater, an electrolytic copper foil having a thickness of 12 μm (trade name “HLS”, manufactured by Nippon Electrolytic Co., Ltd.) was coated so that the thickness after solvent removal was 20 μm, and dried at a temperature of 100 ° C. for 5 minutes. Then
Drying conditions under reduced pressure: 200 ° C. × 24 hr (the degree of reduced pressure varied between 10 and 100 Pa due to volatilization of the solvent)
Heating under nitrogen (flow rate; 20 L / min); 260 ° C. × 10 hr
And heat treated.

Synthesis example 1 (resin 1)
In a reaction vessel, 172 g of trimellitic anhydride (90 mol%, manufactured by Mitsubishi Gas Chemical Co., Inc.), 3,
3 ', 4, 4'-biphenyltetracarboxylic dianhydride 29 g (10 mol%, manufactured by Mitsubishi Chemical Corporation), 1,5-naphthalene diisocyanate 210 g (100 mol%, manufactured by Sumitomo Bayer Urethane Co., Ltd.), 1 g of diazabicycloundecene (manufactured by San Apro Co., Ltd.) and 1836 g of N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP) (manufactured by Mitsubishi Chemical Corporation) (polymer concentration 15%) were added. The temperature was raised to 100 ° C. in 2 hours, and the reaction was allowed to proceed for 5 hours. Subsequently, NMP534g (polymer concentration 12 weight%) was added, and it cooled to room temperature. The obtained polymer dope was yellowish brown transparent and the polymer was dissolved in NMP. The logarithmic viscosity and imidation ratio were as shown in Table 1. In addition, a resin film (single layer) obtained by etching and removing the metal foil of the metal laminate formed by the method described in Example 1 with 35% ferric chloride (40 ° C.) using this resin solution. Table 1 shows Tg, strength, elongation, and elastic modulus.
The purity of each monomer was 99% or more.

Synthesis Examples 2-9
A resin varnish was prepared under the same polymerization conditions as in Synthesis Example 1 except that the monomer composition was changed to the contents shown in Table 1. The logarithmic viscosity, imidization rate, Tg, strength, elongation, and elastic modulus were as shown in Table 1.

Example 1, Example 2, Example 5, Comparative Examples 1-5
Using the polymer solution obtained as described above, a flexible metal-clad laminate was prepared under the following molding process conditions, and various characteristics shown in Table 2 were evaluated.
(A) Initial drying Using the two types of resin solutions obtained above, a flexible metal-clad laminate with an initially dried base resin layer having a two-layer structure was obtained in the laminated structure as shown in Table 2. .
That is, using a knife coater on a 12 μm thick electrolytic copper foil (trade name “NA-VLP”, manufactured by Mitsui Metal Mining Co., Ltd.), the thickness of the first layer is as shown in Table 2. The eyes were coated and dried at a temperature of 100 ° C. for 5 minutes. Next, in the same manner, the coating is further coated and dried at a temperature of 100 ° C. for 10 minutes so that the thickness after solvent removal is as shown in Table 2. Thus, an initially dried flexible metal-clad laminate is obtained. It was.
(B) Secondary drying The above initially dried laminate was wound around an aluminum can with an outer diameter of 16 inches so that the coated surface was on the outside, and was heat-treated with a vacuum dryer or an inert oven under the conditions shown below. . The solvent in the coating film of the obtained laminate was completely removed.
Drying conditions under reduced pressure: 200 ° C. × 24 hr (the degree of reduced pressure varied between 10 and 100 Pa due to volatilization of the solvent)
Heating under nitrogen (flow rate; 20 L / min); 260 ° C. × 10 hr

Examples 3 and 4
Resin described in Table 2 by changing the copper foil to the electrolytic copper foil “U-WZ” manufactured by Furukawa Circuit Foil Co., Ltd. having a thickness of 12 μm and the electrolytic copper foil “HLS” manufactured by Nippon Electrolytic Co., Ltd. having a thickness of 12 μm. A flexible metal laminate was prepared in the same manner as in Example 2 except that the characteristics shown in Table 2 were evaluated.

Meaning of abbreviations
HR-16N: Polyamideimide resin varnish manufactured by Toyobo Co., Ltd.
TMA: trimellitic anhydride
BTDA; 3, 3, '4, 4'-benzophenone tetracarboxylic dianhydride
BPDA; 3, 3, '4, 4'-biphenyltetracarboxylic dianhydride
PMA: pyromelotic anhydride
TPA; terephthalic acid
NDI: 1,5-naphthalene diisocyanate
TODI; O-tolidine diisocyanate
CHE: Dimensional change rate of moisture absorption

As described above, the flexible metal laminate of the present invention is composed of a plurality of resin compositions having low flexibility, folding resistance, humidity dimensional change rate and high Tg. Excellent in terms of flexibility, dimensional accuracy, and moisture resistance reliability. Furthermore, since the resin composition to be used is soluble in an organic solvent, it can be produced at low cost without the need for heat treatment at high temperatures. Therefore, since a flexible substrate that can be used even for high-density mounting substrate applications can be manufactured at low cost, there are significant industrial advantages.

Claims (7)

  A flexible metal laminate in which a metal foil is laminated on at least one surface of a heat resistant resin film, and a circuit pattern is formed by a subtractive method according to IPC-FC241 (IPC-TM-650, 2.4.9 (A)). Using the prepared sample, the adhesive strength after being treated for 500 hours under heating and humidification at 85 ° C. and 85% RH is 4 N / cm or more, and the heat-resistant resin film comprises two layers. A flexible metal laminate, wherein the heat-resistant resin film layer on the side in contact with the metal foil is a thermoplastic resin having a Tg of 350 ° C. or higher. A flexible metal laminate in which a metal foil is laminated on one side of a heat resistant resin film, the heat resistant resin film comprising two layers, and the thickness (T1) of the resin layer on the side in contact with the metal foil and the metal foil The flexible metal laminate according to claim 1, wherein the ratio (T1) / (T2) of the thickness (T2) of the resin layer on the non-contact side is 0.05 to 5.   The flexible metal laminate according to claim 1 or 2, wherein the heat-resistant resin film is soluble in an organic solvent and is a thermoplastic polyamide-imide resin. The flexible metal laminate according to any one of claims 1 to 3, wherein a metal foil is formed on one side, wherein the heat-resistant resin layer on the side in contact with the metal foil is
a) When the total amount of the acid component is 100 mol%, the total amount of the amine component is 100 mol%, and the total of the acid component and the amine component is 200 mol%, the monomer component having a naphthalene group is 80 mol% or more,
And b) a molar ratio of imide bond to amide bond is 99/1 to 60/40 molar ratio,
c) A flexible metal laminate characterized by being a polyamide-imide resin having an imidization rate of imide bonds of 50% or more. The flexible metal laminate according to any one of claims 1 to 4, wherein a metal foil is formed on one side, and the resin layer on the side not in contact with the metal foil,
a) When the total amount of the acid component is 100 mol%, the total amount of the amine component is 100 mol%, and the total of the acid component and the amine component is 200 mol%, the monomer component having a biphenylene group is 100 mol% or more,
And b) a molar ratio of imide bond to amide bond is 99/1 to 65/35 molar ratio,
c) A flexible metal laminate characterized by being a polyamide-imide resin having an imidization rate of imide bonds of 50% or more. The double-sided flexible metal laminated body obtained by bonding the flexible metal laminated body in any one of Claims 1-5 so that metal foil may be formed in both surfaces.   A flexible printed circuit board obtained from the flexible metal-clad laminate according to claim 1.