JP2020075483A - Manufacturing method of metal-clad laminate, and manufacturing method of circuit board - Google Patents

Abstract

[Problem] To provide a method for producing a metal-clad laminate having a plurality of polyimide layers as insulating resin layers by a casting method, which improves adhesion between polyimide layers while suppressing foaming. [Solution] A method for producing a metal-clad laminate 100 includes the steps of forming a first polyamide resin layer 20A on a metal foil 10A, imidizing polyamic acid in the first polyamide resin layer to form a first polyimide layer 20, performing a surface treatment on the first polyimide layer, forming a second polyamide resin layer 30A on the first polyimide layer, and imidizing polyamic acid in the second polyamide resin layer to form a second polyimide layer 30, thereby forming an insulating resin layer 40. The thickness (L1) of the first polyimide layer is 0.5 to 100 μm, the thickness (L) of the entire insulating resin layer is 5 to less than 200 μm, and the ratio (L/L1) is in the range of more than 1 and less than 400. [Selected Figure] FIG.

Description

  The present invention relates to a method for manufacturing a metal-clad laminate that can be used as a material for a circuit board and the like, and a method for manufacturing a circuit board.

  2. Description of the Related Art In recent years, with the progress of miniaturization, weight reduction, and space saving of electronic devices, a flexible circuit board (FPC; Flexible Printed Circuits) that is thin and lightweight, has flexibility, and has excellent durability even after repeated bending. ) Demand is increasing. FPCs can be mounted in a three-dimensional and high density even in a limited space, so their applications are expanded to wiring of electronic devices such as HDDs, DVDs, mobile phones and smartphones, and parts such as cables and connectors. I am doing it. As an insulating resin used in FPC, attention has been paid to polyimide, which has excellent heat resistance and adhesiveness.

  As a method for producing a metal-clad laminate as an FPC material, a casting method is known in which a polyimide precursor layer is formed by coating a resin solution of polyamic acid on a metal foil and then imidized to form a polyimide layer. There is. When manufacturing a metal-clad laminate having a plurality of polyimide layers as an insulating resin layer by a casting method, generally, on a substrate such as a copper foil, after forming a plurality of polyimide precursor layers sequentially, these Are collectively imidized. However, when a plurality of polyimide precursor layers are collectively imidized, the solvent or imidized water in the polyimide precursor layer cannot be completely exhausted, and the residual solvent or imidized water causes foaming or peeling between the polyimide layers, resulting in a yield. There was a problem of causing a decrease in

  The above-mentioned problems of foaming and peeling can be solved by repeating imidation of each layer of the polyimide precursor layer and applying a polyamic acid resin solution thereon. However, if a polyamic acid resin solution is further applied to the imidized polyimide layer to imidize it, it becomes difficult to obtain sufficient adhesion between the layers. In the prior art, before applying the resin solution of polyamic acid, the surface of the underlying polyimide film or polyimide layer is subjected to a surface treatment such as corona treatment or plasma treatment, thereby making a proposal to improve the adhesion between layers. (For example, Patent Documents 1 and 2).

Japanese Patent No. 5615253 Japanese Patent No. 5480490

  An object of the present invention is to improve adhesion between polyimide layers while suppressing foaming when a metal-clad laminate having a plurality of polyimide layers as insulating resin layers is manufactured by a casting method.

  The present inventors have found that by controlling the thickness of a plurality of polyimide layers formed by a casting method, it is possible to improve the adhesion between polyimide layers while suppressing foaming, and completed the present invention.

That is, the method for producing a metal-clad laminate according to the present invention is a metal-clad laminate comprising an insulating resin layer including a plurality of polyimide layers, and a metal layer laminated on at least one surface of the insulating resin layer. Is a method of manufacturing.
The method for producing a metal-clad laminate of the present invention includes the following steps 1 to 5;
Step 1) A step of forming a single layer or a plurality of layers of the first polyamide resin layer by laminating a solution of a polyamic acid on the metal layer.
Step 2) a step of imidizing the polyamic acid in the first polyamide resin layer to form a first polyimide layer composed of a single layer or a plurality of layers,
Step 3) a step of performing a surface treatment on the surface of the first polyimide layer,
Step 4) a step of applying a solution of a polyamic acid onto the first polyimide layer to form a single layer or a plurality of layers of the second polyamide resin layer,
Step 5) The polyamic acid in the second polyamide resin layer is imidized to form a second polyimide layer composed of a single layer or a plurality of layers, and the first polyimide layer and the second polyimide layer are separated from each other. A step of forming the laminated insulating resin layer,
Is included.
Then, in the method for producing a metal-clad laminate of the present invention, the thickness (L1) of the first polyimide layer is within a range of 0.5 μm or more and 100 μm or less, and the thickness (L) of the entire insulating resin layer. Is in the range of 5 μm or more and less than 200 μm, and the ratio of the L to the L1 (L / L1) is in the range of more than 1 and less than 400.

  In the method for producing a metal-clad laminate of the present invention, the polyimide forming the layer in contact with the metal layer in the first polyimide layer may be a thermoplastic polyimide.

Method for producing a metal-clad laminate of the present invention, the moisture permeability of the metal layer, the thickness 25 [mu] m, when the 25 ° C., may be not more than 100g ^/ m 2 ^/ 24hr.

  The method of manufacturing a circuit board of the present invention includes a step of processing a wiring circuit of the metal layer of the metal-clad laminate manufactured by the above method.

  According to the method of the present invention, it is possible to manufacture a metal-clad laminate having an insulating resin layer having excellent adhesion between polyimide layers while suppressing foaming by using a casting method.

FIG. 4 is a process chart showing a procedure of a method for manufacturing a metal-clad laminate according to an embodiment of the present invention. It is explanatory drawing of the target for position measurement used for the measurement of the dimension change rate after etching. It is explanatory drawing of the evaluation sample used for measurement of the dimensional change rate after etching.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. The method for manufacturing a metal-clad laminate according to the present embodiment, an insulating resin layer including a plurality of polyimide layers, and a metal layer laminated on at least one surface of the insulating resin layer, a metal-clad laminate provided It is a manufacturing method.

  FIG. 1 is a process chart showing a main procedure of a method for manufacturing a metal-clad laminate according to an embodiment of the present invention. The method of this embodiment includes the following steps 1 to 5. In FIG. 1, the numbers next to the arrows mean steps 1 to 5.

Process 1)
In step 1, a solution of polyamic acid is applied onto the metal foil 10A to be the metal layer 10 to form a single layer or a plurality of layers of the first polyamide resin layer 20A. The method of applying the resin solution of the polyamic acid onto the metal foil 10A by the casting method is not particularly limited, and it can be applied with a coater such as a comma, a die, a knife or a lip.
When the first polyamide resin layer 20A has a plurality of layers, for example, a method of repeatedly applying and drying a solution of a polyamic acid on the metal foil 10A is repeated a plurality of times, or by multilayer extrusion, the metal foil 10A is formed on the metal foil 10A. At the same time, a method of applying and drying the polyamic acid in a multi-layered state can be adopted.

  In step 1, as will be described later, the first polyamide resin layer 20A is formed so that the thickness (L1) of the first polyimide layer 20 after curing in step 2 is in the range of 0.5 μm or more and 100 μm or less. It is preferably formed. In the casting method, the polyamic acid resin layer is imidized in a state of being fixed to the metal foil 10A, so that the expansion and contraction change of the polyimide layer during the imidization process can be suppressed, and the thickness and dimensional accuracy can be maintained.

  The material of the metal foil 10A is not particularly limited, but for example, copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and These alloys etc. are mentioned. Among these, copper or copper alloy is particularly preferable. As the copper foil, a rolled copper foil or an electrolytic copper foil may be used, and a commercially available copper foil can be preferably used.

  In the present embodiment, for example, when used for manufacturing FPC, the metal layer 10 has a preferable thickness within a range of 3 to 80 μm, and more preferably within a range of 5 to 30 μm.

  The surface of the metal foil 10A used as the metal layer 10 may be subjected to surface treatment such as rust prevention treatment, siding, aluminum alcoholate, aluminum chelate, and silane coupling agent. Further, the metal foil 10A may be in the form of a cut sheet, a roll, an endless belt, or the like, but in order to obtain productivity, the metal foil 10A is in the form of a roll or an endless belt for continuous production. It is efficient to make it possible. Further, from the viewpoint of more exerting the effect of improving the wiring pattern accuracy in the circuit board, the metal foil 10A is preferably a long roll-shaped one.

Further, the moisture permeability of the metal layer 10, for example a thickness 25 [mu] m, at 25 ° C., preferably not more than 100g ^/ m 2 ^/ 24hr. When the water vapor permeability of the metal layer 10 is low and the solvent or imidized water does not easily escape from the metal layer 10 side, the effect of the method of the present embodiment is greatly exhibited.

Process 2)
In step 2, the polyamic acid in the first polyamide resin layer 20A formed in step 1 is imidized to form the first polyimide layer 20 composed of a single layer or a plurality of layers. By imidizing the polyamic acid contained in the first polyamide resin layer 20A, most of the solvent and imidized water contained in the first polyamide resin layer 20A can be removed.

  The method for imidizing the polyamic acid is not particularly limited, and for example, heat treatment of heating at a temperature condition of 80 to 400 ° C. for a time of 1 to 60 minutes is preferable. The heat treatment is preferably performed in a low oxygen atmosphere in order to suppress the oxidation of the metal layer 10, and specifically, in an inert gas atmosphere such as nitrogen or a rare gas, a reducing gas atmosphere such as hydrogen, or a vacuum. It is preferable to carry out in.

Process 3)
In step 3, the surface of the first polyimide layer 20 is surface-treated.
The surface treatment is not particularly limited as long as it is a treatment capable of improving the interlayer adhesion between the first polyimide layer 20 and the second polyimide layer 30, and examples thereof include plasma treatment, corona treatment, flame treatment, ultraviolet treatment, and ozone. Examples thereof include treatment, electron beam treatment, radiation treatment, sandblasting, hairline processing, embossing, chemical treatment, steam treatment, surface grafting treatment, electrochemical treatment, and primer treatment. Particularly, when the first polyimide layer 20 is a thermoplastic polyimide layer, surface treatment such as plasma treatment, corona treatment, and ultraviolet treatment is preferable, and the condition thereof is, for example, 300 W / min / m ² or less. preferable.

Process 4)
In step 4, a single layer or a plurality of layers of the second polyamide resin layer 30A is laminated by applying a solution of a polyamic acid onto the first polyimide layer 20 subjected to the surface treatment in step 3. To do. The method of applying the resin solution of the polyamic acid onto the first polyimide layer 20 by the casting method is not particularly limited, and it can be applied with a coater such as a comma, a die, a knife or a lip.
When the second polyamide resin layer 30A has a plurality of layers, for example, a method of repeatedly applying and drying a solution of a polyamic acid on the first polyimide layer 20 a plurality of times, or by multi-layer extrusion, It is possible to adopt a method in which polyamic acid is simultaneously laminated in multiple layers on the first polyimide layer 20 and applied and dried.

  In Step 4, as will be described later, the second polyamide resin layer 30A is formed after the next Step 5 so that the total thickness (L) of the insulating resin layer 40 is within the range of 5 μm or more and less than 200 μm. Is preferred.

Process 5)
In step 5, the polyamic acid contained in the second polyamide resin layer 30A is imidized to be converted into the second polyimide layer 30, and the insulating resin containing the first polyimide layer 20 and the second polyimide layer 30. Form layer 40.
In step 5, the polyamic acid contained in the second polyamide resin layer 30A is imidized to synthesize polyimide. The imidization method is not particularly limited and can be carried out under the same conditions as in step 2.

<Arbitrary process>
The method of the present embodiment can include any step other than the above.

  Through the above steps 1 to 5, the metal-clad laminate 100 having the insulating resin layer 40 having excellent adhesion between the first polyimide layer 20 and the second polyimide layer 30 can be manufactured. In the method of the present embodiment, even if the first polyimide layer 20 is formed on the metal layer 10 by a casting method, imidization is performed before the second polyimide layer 30 is formed. Since water is removed, problems such as foaming and delamination do not occur. In addition, the adhesion between the first polyimide layer 20 and the second polyimide layer 30 is secured by performing a surface treatment on the first polyimide layer 20 before forming the second polyamide resin layer 30A. it can.

In the insulating resin layer 40 of the metal-clad laminate 100 manufactured by the method of the present embodiment, the thickness (L1) of the first polyimide layer is in the range of 0.5 μm or more and 100 μm or less.
Here, when the first polyimide layer 20 is a single layer, its thickness (L1) is preferably in the range of 0.5 μm or more and 5 μm or less, and more preferably in the range of 1 μm or more and 3 μm or less. In this case, in step 2, most of the solvent and imidized water can be removed by curing in a thin state where the thickness (L1) after imidization is 5 μm or less. Further, when the first polyimide layer 20 is a single layer, by controlling the thickness (L1) to be 5 μm or less, it is possible to reduce the peel strength with the metal layer 10 and the metal layer 10. Since the polyamic acid does not remain at the interface and can be completely imidized, the peel strength can be improved. When the thickness (L1) is less than 0.5 μm, the adhesiveness with the metal layer 10 is deteriorated and the insulating resin layer 40 is easily peeled off.
On the other hand, when the first polyimide layer 20 is composed of a plurality of layers, its thickness (L1) is preferably in the range of 5 μm or more and 100 μm or less, and more preferably in the range of 25 μm or more and 100 μm or less. When the first polyimide layer 20 is composed of a plurality of layers, if the thickness (L1) exceeds 100 μm, foaming tends to occur.

The total thickness (L) of the insulating resin layer 40 is in the range of 5 μm or more and less than 200 μm.
Here, when the first polyimide layer 20 is a single layer, the thickness (L) of the entire insulating resin layer 40 is preferably in the range of 5 μm or more and less than 30 μm, and more preferably in the range of 10 μm or more and 25 μm or less. When the first polyimide layer 20 is a single layer and the total thickness (L) of the insulating resin layer 40 is less than 5 μm, the foaming suppressing effect, which is an effect of the invention, is less likely to be exhibited, and the dimensional stability is improved. It is difficult to obtain the effect.
On the other hand, when the first polyimide layer 20 is composed of a plurality of layers, the total thickness (L) of the insulating resin layer 40 is preferably in the range of 10 μm or more and less than 200 μm, and more preferably in the range of 50 μm or more and less than 200 μm. When the first polyimide layer 20 is composed of a plurality of layers and the total thickness (L) of the insulating resin layer 40 is 200 μm or more, foaming is likely to occur.

As described above, the thickness (L1) of the first polyimide layer 20 and the total thickness (L) of the insulating resin layer 40 affect foaming suppression, dimensional stability improvement, and adhesiveness with the metal layer 10, The ratio (L / L1) between the thickness (L) and the thickness (L1) is more than 1 and less than 400.
The ratio (L / L1) is preferably in the range of more than 1 and less than 60, more preferably 4 or more and 45 or less, and most preferably 5 or more and 30 or less.

  The insulating resin layer 40 may include a polyimide layer other than the first polyimide layer 20 and the second polyimide layer 30. Further, the polyimide layer forming the insulating resin layer 40 may contain an inorganic filler, if necessary. Specific examples include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride and the like. These can be used alone or in combination of two or more.

<Polyimide>
Next, a preferred polyimide for forming the first polyimide layer 20 and the second polyimide layer 30 will be described. For forming the first polyimide layer 20 and the second polyimide layer 30, an acid anhydride component and a diamine component which are generally used as raw materials for synthesizing polyimide can be used without particular limitation.

  In the metal-clad laminate 100, the polyimide forming the first polyimide layer 20 may be either thermoplastic polyimide or non-thermoplastic polyimide, but it is easy to secure adhesiveness with the underlying metal layer 10. For reasons, thermoplastic polyimides are preferred.

Further, the polyimide forming the second polyimide layer 30 may be either thermoplastic polyimide or non-thermoplastic polyimide, but when the non-thermoplastic polyimide is used, the effect of the invention is remarkably exhibited.
That is, even if the imidization is completed by laminating a resin layer of a polyamic acid, which is a precursor of a non-thermoplastic polyimide, by a method such as a casting method on the polyimide layer that has been imidized, usually, the adhesion between the polyimide layers I can hardly get sex. However, in the present embodiment, by performing the surface treatment on the first polyimide layer 20 as described above and then laminating the second polyamide resin layer 30A, the polyimide constituting the second polyimide layer 30 is heated. Excellent adhesion is obtained between the first polyimide layer 20 and the first polyimide layer 20, regardless of whether it is plastic or non-thermoplastic. In addition, when the second polyimide layer 30 is a non-thermoplastic polyimide, it can function as a main layer (base layer) that secures the mechanical strength of the polyimide layer in the metal-clad laminate 100.

  From the above, in the metal-clad laminate 100, forming a structure in which a thermoplastic polyimide layer as the first polyimide layer 20 and a non-thermoplastic polyimide layer as the second polyimide layer 30 are laminated is the most preferable embodiment. ..

Polyimide includes low thermal expansion polyimide and high thermal expansion polyimide. Usually, thermoplastic polyimide has high thermal expansion and non-thermoplastic polyimide has low thermal expansion. For example, when the first polyimide layer 20 is a thermoplastic polyimide layer, the coefficient of thermal expansion is preferably in the range of more than 30 × 10 ⁻⁶ and 80 × 10 ⁻⁶ / K or less. By setting the coefficient of thermal expansion of the thermoplastic polyimide layer within the above range, it is possible to secure the adhesiveness with the metal layer 10 as the first polyimide layer 20. Moreover, by making the second polyimide layer 30 a low-expansion polyimide layer, it can function as a main layer (base layer) that secures the dimensional stability of the polyimide layer in the metal-clad laminate 100. Specifically, the coefficient of thermal expansion of the low expansion polyimide layer is in the range of 1 × 10 ⁻⁶ to 30 × 10 ⁻⁶ (1 / K), preferably 1 × 10 ^{−6 to} 25 × 10 ⁻⁶ ( The range of 1 / K) is more preferable, and the range of 10 × 10 ^{−6 to} 25 × 10 ⁻⁶ (1 / K) is more preferable. Further, since the non-thermoplastic polyimide has a low thermal expansion coefficient, the thermal expansion coefficient can be suppressed low by increasing the thickness ratio of the non-thermoplastic polyimide layer. The first polyimide layer 20 and the second polyimide layer 30 can be polyimide layers having a desired coefficient of thermal expansion by appropriately changing the combination of raw materials used, thickness, and drying / curing conditions.

In addition, "thermoplastic polyimide" is generally a polyimide whose glass transition temperature (Tg) can be clearly confirmed, but in the present invention, it is measured using a dynamic viscoelasticity measuring device (DMA), 30 ° C. The polyimide having a storage elastic modulus of 1.0 × 10 ⁹ Pa or more and a storage elastic modulus at 350 ° C. of less than 1.0 × 10 ⁸ Pa. Further, the "non-thermoplastic polyimide" generally means a polyimide that does not soften or adhere even when heated, but in the present invention, it is measured using a dynamic viscoelasticity measuring device (DMA), 30 A polyimide having a storage elastic modulus at 0 ° C of 1.0 x 10 ⁹ Pa or higher and a storage elastic modulus at 350 ° C of 1.0 x 10 ⁸ Pa or higher.

An aromatic diamine compound, an aliphatic diamine compound, or the like can be used as the diamine compound which is a raw material of the polyimide, but for example, an aromatic diamine compound represented by NH ₂ —Ar ₁ —NH ₂ is preferable. Examples of Ar1 include those selected from the groups represented by the following formula. Ar1 may have a substituent, but preferably does not have, or when it has, the substituent is preferably a lower alkyl or lower alkoxy group having 1 to 6 carbon atoms. These aromatic diamine compounds may be used alone or in combination of two or more.

As the acid anhydride to be reacted with the diamine compound, aromatic tetracarboxylic acid anhydride is preferable from the viewpoint of ease of synthesis of polyamic acid. Although the aromatic tetracarboxylic acid anhydride is not particularly limited, for example, a compound represented by O (CO) ₂ Ar2 (CO) ₂ O is preferable. Here, Ar2 is exemplified by a tetravalent aromatic group represented by the following formula. The substitution position of the acid anhydride group [(CO) ₂ O] is arbitrary, but a symmetrical position is preferable. Ar2 may have a substituent, but preferably has no substituent, or when it has, the substituent is preferably a lower alkyl group having 1 to 6 carbon atoms.

(Synthesis of polyimide)
The polyimide constituting the polyimide layer can be produced by reacting an acid anhydride and a diamine in a solvent to generate a precursor resin and then subjecting it to ring closure by heating. For example, a polyimide precursor is prepared by dissolving an acid anhydride component and a diamine component in substantially equimolar amounts in an organic solvent and stirring the mixture at a temperature in the range of 0 to 100 ° C. for 30 minutes to 24 hours to cause a polymerization reaction. A polyamic acid is obtained. In the reaction, the reaction components are dissolved in the organic solvent so that the amount of the produced precursor is in the range of 5 to 30% by weight, preferably 10 to 20% by weight. Examples of the organic solvent used in the polymerization reaction include N, N-dimethylformamide, N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, 2-butanone, dimethylsulfoxide, dimethyl sulfate, cyclohexanone, dioxane. , Tetrahydrofuran, diglyme, triglyme and the like. Two or more of these solvents may be used in combination, and further aromatic hydrocarbons such as xylene and toluene may be used in combination. The amount of such an organic solvent used is not particularly limited, but the amount used is such that the concentration of the polyamic acid solution (polyimide precursor solution) obtained by the polymerization reaction is about 5 to 30% by weight. It is preferable to adjust the above to use. The synthesized precursor is usually advantageously used as a reaction solvent solution, but it can be concentrated, diluted or replaced with another organic solvent if necessary. Further, the precursor is generally used because it is excellent in solvent solubility.

  In the synthesis of polyimide, each of the acid anhydride and diamine may be used alone or in combination of two or more. Controlling thermal expansion, adhesiveness, storage elastic modulus, glass transition temperature, etc. by selecting the type of acid anhydride and diamine and the respective molar ratios when two or more acid anhydrides or diamines are used. can do. When the polyimide has a plurality of polyimide structural units, it may exist as a block or may exist at random, but preferably exists at random.

  As described above, the metal-clad laminate obtained in the present embodiment has excellent adhesion between the first polyimide layer 20 and the second polyimide layer 30, and is used as a circuit board material typified by FPC. The reliability of electronic devices can be improved.

<Circuit board>
A circuit board according to an embodiment of the present invention includes an insulating resin layer including a plurality of polyimide layers, and a wiring layer laminated on at least one surface of the insulating resin layer. This circuit board can be manufactured by processing the metal layer 10 of the metal-clad laminate 100 obtained by the method of the above-described embodiment into a pattern by a conventional method to form a wiring layer. The patterning of the metal layer 10 can be performed by any method using, for example, a photolithography technique and etching.

  In addition, as a process that is usually performed when manufacturing a circuit board, for example, a through-hole process in a pre-process, a terminal plating process in a post-process, and an outer shape process can be performed according to a conventional method.

  Hereinafter, the features of the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited to the examples. In the following examples, various measurements and evaluations are based on the following unless otherwise specified.

[Viscosity measurement]
The viscosity of the resin was measured at 25 ° C. using an E-type viscometer (trade name: DV-II + Pro, manufactured by Brookfield). The rotation speed was set so that the torque was 10% to 90%, and 2 minutes after the measurement was started, the value when the viscosity became stable was read.

[Evaluation of foaming]
When peeling is confirmed between the first polyimide layer and the second polyimide layer, or when a crack is generated in the polyimide layer, it is defined as "foaming", and when there is no peeling or cracking, "no foaming" And

[Measurement of dimensional change rate after etching]
A metal-clad laminate having a size of 80 mm × 80 mm was prepared. After providing a dry film resist on the metal layer of this laminated plate, it is exposed and developed to form 16 resist patterns having a diameter of 1 mm so as to form a square shape as a whole, as shown in FIG. Then, a position measurement target capable of measuring 5 positions at 50 mm intervals in the longitudinal direction (MD) and the transverse direction (TD) was prepared.

Regarding the prepared sample, the distance between the targets in the vertical direction (MD) and the horizontal direction (TD) of the resist pattern in the target for position measurement was measured in an atmosphere of a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5%. After the measurement, the exposed portion of the metal layer at the opening of the resist pattern is removed by etching (etching solution temperature: 40 ° C. or lower, etching time: within 10 minutes), and as shown in FIG. 3, 16 metal layers are removed. An evaluation sample having a residual point was prepared. This evaluation sample was allowed to stand for 24 ± 4 hours in an atmosphere of temperature: 23 ± 2 ° C., relative humidity: 50 ± 5% for 24 ± 4 hours, and then the distance between the remaining points of the metal layer in the machine direction (MD) and the transverse direction (TD). Was measured. The dimensional change rates for the normal state at each of the five locations in the vertical direction and the horizontal direction are calculated, and the average value of each is used as the dimensional change rate after etching.
Each dimensional change rate was calculated by the following mathematical formula.
Dimensional change rate after etching (%) = (B−A) / A × 100
A: Distance between targets after resist development B: Distance between remaining metal layer points after metal layer etching Absolute value of dimensional change rate after etching is 0.2% or less is “good”, 0.2 %, And 0.4% or less is “OK”, and 0.4% or more is “NO”.

[Curl Evaluation]
The film curl is obtained by etching the entire surface of the copper foil of the metal-clad laminate and removing the copper foil, and placing the first polyimide layer of the polyimide film having a size of 100 mm × 100 mm on the lower side and setting the floating heights at the four corners. It was measured. The case where the average value of the floating heights at the four corners exceeded 10 mm was evaluated as "curled".

[Evaluation of moisture permeability]
In accordance with JIS Z0208, a moisture absorbent / calcium chloride (anhydrous) was enclosed in a moisture permeable cup, and the increase in mass of the cup after 24 hours was evaluated as the amount of water vapor permeation.

[Measurement of moisture absorption rate]
Two polyimide film test pieces (width 4 cm x length 25 cm) were prepared and dried at 80 ° C for 1 hour. Immediately after drying, the sample was placed in a constant temperature and humidity chamber at 23 ° C./50% RH, allowed to stand for 24 hours or more, and calculated from the weight change before and after that by the following formula.
Moisture absorption rate (wt%) = [(weight after moisture absorption−weight after drying) / weight after drying] × 100

[Measurement of glass transition temperature (Tg)]
The polyimide film (10 mm × 40 mm) was heated from 20 ° C. to 500 ° C. at 5 ° C./min with a dynamic thermomechanical analyzer (DMA: TA Instruments Japan Co., Ltd., trade name: RSA-G2). The dynamic viscoelasticity at that time was measured, and the glass transition temperature (Tan δ maximum value: ° C) was determined.

[Measurement of storage elastic modulus]
The storage elastic modulus was measured using a dynamic viscoelasticity measuring device (DMA). A polyimide having a storage elastic modulus at 30 ° C. of 1.0 × 10 ⁹ Pa or more and a storage elastic modulus at 350 ° C. of 1.0 × 10 ⁸ Pa or more is referred to as “non-thermoplastic polyimide”, and the storage elasticity at 30 ° C. A polyimide having a modulus of 1.0 × 10 ⁹ Pa or more and a storage elastic modulus at 350 ° C. of less than 1.0 × 10 ⁸ Pa is referred to as “thermoplastic polyimide”.

[Measurement of coefficient of thermal expansion (CTE)]
A polyimide film having a thickness of 25 μm and a size of 3 mm × 20 mm was heated from 30 ° C. to 300 ° C. at a constant heating rate while applying a load of 5.0 g using a thermomechanical analyzer (Bruker, trade name; 4000 SA). After being heated and further maintained at that temperature for 10 minutes, it was cooled at a rate of 5 ° C./min, and the average coefficient of thermal expansion (thermal expansion coefficient) from 250 ° C. to 100 ° C. was obtained.

Abbreviations used in Examples and Comparative Examples represent the following compounds.
m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl TPE-R: 1,3-bis (4-aminophenoxy) benzene BAPP: 2,2-bis [4- (4-aminophenoxy) Phenyl] propane TFMB: 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl BAFL: 9,9-bis (4-aminophenyl) fluorene PMDA: pyromellitic dianhydride DMAc: N, N-dimethylacetamide

(Synthesis example 1)
75.149 g of m-TB (353.42 mmol) and 850 g of DMAc were put into a 1000 ml separable flask, and the mixture was stirred at room temperature under a nitrogen stream. After completely dissolving, 74.851 g of PMDA (342.82 mmol) was added, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution A. The viscosity of the obtained polyamic acid solution A was 22,700 cP. The polyimide after imidization of the obtained polyamic acid was non-thermoplastic. The CTE of the obtained polyimide film (thickness: 25 μm) was 6.4 ppm / K.

(Synthesis example 2)
A 1000 ml separable flask was charged with 65.054 g of m-TB (310.65 mmol), 10.090 g of TPE-R (34.52 mmol) and 850 g of DMAc and stirred at room temperature under a nitrogen stream. After completely dissolving, 73.856 g of PMDA (338.26 mmol) was added, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution B. The viscosity of the obtained polyamic acid solution B was 26,500 cP. The polyimide after imidation of the obtained polyamic acid was non-thermoplastic and had a glass transition temperature (Tg) of 303 ° C. The obtained polyimide film (thickness; 25 [mu] m) CTE of is 16.2ppm / K, moisture absorption is 0.61% by weight, the moisture permeability was ^64g / m 2 / 24hr.

(Synthesis example 3)
A 1000 ml separable flask was charged with 89.621 g of TFMB (279.33 mmol) and 850 g of DMAc and stirred at room temperature under a nitrogen stream. After completely dissolving, 60.379 g of PMDA (276.54 mmol) was added and stirred at room temperature for 4 hours to obtain a polyamic acid solution C. The viscosity of the obtained polyamic acid solution C was 21,200 cP. The polyimide after imidization of the obtained polyamic acid was non-thermoplastic. The CTE of the obtained polyimide film (thickness: 25 μm) was 0.5 ppm / K.

(Synthesis example 4)
A 1000 ml separable flask was charged with 49.928 g of TFMB (155.70 mmol), 33.102 g of m-TB (155.70 mmol) and 850 g of DMAc and stirred at room temperature under a nitrogen stream. After completely dissolving, 66.970 g of PMDA (307.03 mmol) was added, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution D. The viscosity of the obtained polyamic acid solution D was 21,500 cP. The polyimide after imidization of the obtained polyamic acid was non-thermoplastic. The CTE of the obtained polyimide film (thickness: 25 μm) was 6.0 ppm / K.

(Synthesis example 5)
A 300 ml separable flask was charged with 29.492 g of BAPP (71.81 mmol) and 255 g of DMAc and stirred at room temperature under a nitrogen stream. After completely dissolving, 15.508 g of PMDA (71.10 mmol) was added, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution E. The viscosity of the obtained polyamic acid solution E was 10,700 cP. The polyimide after imidation of the obtained polyamic acid was thermoplastic and had a glass transition temperature (Tg) of 312 ° C. The obtained polyimide film (thickness; 25 [mu] m) CTE of is 63.1ppm / K, moisture absorption is 0.54% by weight, the moisture permeability was ^64g / m 2 / 24hr.

(Synthesis example 6)
25.889 g of TPE-R (88.50 mmol) and 255 g of DMAc were put into a 300 ml separable flask, and the mixture was stirred at room temperature under a nitrogen stream. After completely dissolved, 19.111 g of PMDA (87.62 mmol) was added, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution F. The viscosity of the obtained polyamic acid solution F was 13,200 cP. The polyimide after imidization of the obtained polyamic acid was non-thermoplastic. The CTE of the obtained polyimide film (thickness: 25 μm) was 57.7 ppm / K.

(Synthesis example 7)
27.782 g of BAFL (79.73 mmol) and 255 g of DMAc were put into a 300 ml separable flask, and the mixture was stirred at room temperature under a nitrogen stream. After completely dissolving, 17.218 g of PMDA (78.94 mmol) was added, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution G. The viscosity of the obtained polyamic acid solution G was 10,400 cP. The polyimide after imidization of the obtained polyamic acid was non-thermoplastic. The CTE of the obtained polyimide film (thickness: 25 μm) was 52.0 ppm / K.

[Example 1]
A polyamic acid solution E to be the first polyimide layer was uniformly applied onto a 12 μm-thick electrolytic copper foil so that the thickness after curing was 2 μm, and the temperature was raised stepwise from 120 ° C. to 360 ° C. The solvent was removed and imidization was performed. The obtained first polyimide layer was corona-treated at 120 W · min / m ² . Then, a polyamic acid solution A to be the second polyimide layer was uniformly applied on it so that the thickness after curing would be 25 μm, and then dried by heating at 120 ° C. for 3 minutes to remove the solvent. Then, the temperature was raised stepwise from 130 ° C. to 360 ° C. for imidization to prepare a metal-clad laminate 1. The thickness (L1) of the first polyimide layer was 2 μm, the thickness (L) of the entire insulating resin layer was 27 μm, and the ratio (L / L1) was 13.5. An adhesive tape was attached to the resin surface of the prepared metal-clad laminate 1, and a peeling test was performed by instantaneously peeling it off in the vertical direction. However, peeling between the first polyimide layer and the second polyimide layer was observed. There wasn't.

[Example 2]
A metal-clad laminate 2 was prepared in the same manner as in Example 1 except that the polyamic acid solution F was used instead of the polyamic acid solution E. A peeling test was performed on the prepared metal-clad laminate 2 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 3]
A metal-clad laminate 3 was prepared in the same manner as in Example 1 except that the polyamic acid solution G was used instead of the polyamic acid solution E. A peeling test was performed on the prepared metal-clad laminate 3 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 4]
A metal-clad laminate 4 was prepared in the same manner as in Example 1 except that the polyamic acid solution C was used instead of the polyamic acid solution E. A peeling test was performed on the prepared metal-clad laminate 4 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 5]
A metal-clad laminate 5 was prepared in the same manner as in Example 1 except that the polyamic acid solution B was used instead of the polyamic acid solution A. A peeling test was conducted on the prepared metal-clad laminate 5 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 6]
A metal-clad laminate 6 was prepared in the same manner as in Example 1 except that the polyamic acid solution B was used instead of the polyamic acid solution A, and the polyamic acid solution F was used instead of the polyamic acid solution E. .. A peeling test was performed on the prepared metal-clad laminate 6 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 7]
A metal-clad laminate 7 was prepared in the same manner as in Example 1 except that the polyamic acid solution B was used instead of the polyamic acid solution A, and the polyamic acid solution G was used instead of the polyamic acid solution E. .. A peeling test was performed on the prepared metal-clad laminate 7 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 8]
A metal-clad laminate 8 was prepared in the same manner as in Example 1 except that the polyamic acid solution B was used instead of the polyamic acid solution A, and the polyamic acid solution A was used instead of the polyamic acid solution E. .. A peeling test was performed on the prepared metal-clad laminate 8 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 9]
A metal-clad laminate 9 was prepared in the same manner as in Example 1 except that the polyamic acid solution B was used instead of the polyamic acid solution A, and the polyamic acid solution C was used instead of the polyamic acid solution E. .. A peeling test was performed on the prepared metal-clad laminate 9 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 10]
A metal-clad laminate 10 was prepared in the same manner as in Example 1 except that the polyamic acid solution C was used instead of the polyamic acid solution A. A peeling test was performed on the prepared metal-clad laminate 10 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 11]
A metal-clad laminate 11 was prepared in the same manner as in Example 1 except that the polyamic acid solution C was used instead of the polyamic acid solution A, and the polyamic acid solution F was used instead of the polyamic acid solution E. .. A peeling test was conducted on the prepared metal-clad laminate 11 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 12]
A metal-clad laminate 12 was prepared in the same manner as in Example 1 except that the polyamic acid solution C was used instead of the polyamic acid solution A, and the polyamic acid solution G was used instead of the polyamic acid solution E. .. A peeling test was conducted on the prepared metal-clad laminate 12 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 13]
A metal-clad laminate 13 was prepared in the same manner as in Example 1 except that the polyamic acid solution C was used instead of the polyamic acid solution A, and the polyamic acid solution A was used instead of the polyamic acid solution E. .. A peeling test was performed on the prepared metal-clad laminate 13 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 14]
A metal-clad laminate 14 was prepared in the same manner as in Example 1 except that the polyamic acid solution D was used instead of the polyamic acid solution A. A peeling test was conducted on the prepared metal-clad laminate 14 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 15]
A metal-clad laminate 15 was prepared in the same manner as in Example 1 except that the polyamic acid solution D was used instead of the polyamic acid solution A, and the polyamic acid solution F was used instead of the polyamic acid solution E. .. A peeling test was conducted on the prepared metal-clad laminate 15 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 16]
A metal-clad laminate 16 was prepared in the same manner as in Example 1 except that the polyamic acid solution D was used instead of the polyamic acid solution A, and the polyamic acid solution G was used instead of the polyamic acid solution E. .. A peeling test was performed on the prepared metal-clad laminate 16 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 17]
A metal-clad laminate 17 was prepared in the same manner as in Example 1 except that the polyamic acid solution D was used instead of the polyamic acid solution A, and the polyamic acid solution A was used instead of the polyamic acid solution E. .. A peeling test was performed on the prepared metal-clad laminate 17 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

[Example 18]
A metal-clad laminate 18 was prepared in the same manner as in Example 1 except that the polyamic acid solution D was used instead of the polyamic acid solution A, and the polyamic acid solution C was used instead of the polyamic acid solution E. .. A peeling test was performed on the prepared metal-clad laminate 18 in the same manner as in Example 1, but no peeling between the first polyimide layer and the second polyimide layer was observed.

Comparative Example 1
A metal-clad laminate 19 was prepared in the same manner as in Example 1 except that the corona treatment was not performed. When a peeling test was performed on the prepared metal-clad laminate 19 in the same manner as in Example 1, delamination of the first polyimide layer and the second polyimide layer occurred.

Comparative example 2
A metal-clad laminate 20 was prepared in the same manner as in Example 2 except that the corona treatment was not performed. When a peeling test was performed on the prepared metal-clad laminate 20 in the same manner as in Example 1, delamination of the first polyimide layer and the second polyimide layer occurred.

Comparative Example 3
A metal-clad laminate 21 was prepared in the same manner as in Example 14 except that the corona treatment was not performed. When a peeling test was performed on the prepared metal-clad laminate 21 in the same manner as in Example 1, delamination of the first polyimide layer and the second polyimide layer occurred.

Comparative Example 4
A metal-clad laminate 22 was prepared in the same manner as in Example 15 except that the corona treatment was not performed. When a peeling test was performed on the prepared metal-clad laminate 22 in the same manner as in Example 1, delamination of the first polyimide layer and the second polyimide layer occurred.

[Example 19]
A polyamic acid solution E to be the first polyimide layer was uniformly applied onto a 12 μm thick electrolytic copper foil so that the thickness after curing was 2.5 μm, and then the temperature was raised stepwise from 120 ° C. to 360 ° C. Then, the solvent was removed and imidization was performed. The obtained first polyimide layer was corona-treated at 120 W · min / m ² . Then, a polyamic acid solution A to be the second polyimide layer is uniformly applied thereon so that the thickness after curing is 20 μm, and then a polyamic acid solution E to be the third polyimide layer is applied thereon. Was evenly applied so that the thickness after curing was 2.5 μm, and the solvent was removed by heating and drying at 120 ° C. for 3 minutes. After that, the temperature was raised stepwise from 130 ° C. to 360 ° C. for imidization to prepare a metal-clad laminate 23. The thickness (L1) of the first polyimide layer was 2.5 μm, the thickness (L) of the entire insulating resin layer was 25 μm, and the ratio (L / L1) was 10.0. No bubbling was observed, and no curling of the polyimide film was observed after copper foil etching. The dimensional change rate was “good”.

[Example 20]
Instead of the polyamic acid solution E which becomes the first polyimide layer and the third polyimide layer, the polyamic acid solution F is uniformly applied so that the thickness after curing becomes 2.7 μm, and the second polyimide layer is formed. A metal-clad laminate 24 was prepared in the same manner as in Example 19 except that the polyamic acid solution A was uniformly applied so that the thickness after curing was 19.6 μm. The thickness (L1) of the first polyimide layer was 2.7 μm, the thickness (L) of the entire insulating resin layer was 25 μm, and the ratio (L / L1) was 9.3. No bubbling was observed, and no curling of the polyimide film was observed after copper foil etching. The dimensional change rate was “good”.

[Example 21]
Instead of the polyamic acid solution E which becomes the first polyimide layer and the third polyimide layer, the polyamic acid solution G is uniformly applied so that the thickness after curing becomes 3.2 μm, and the second polyimide layer is formed. A metal-clad laminate 25 was prepared in the same manner as in Example 19 except that the polyamic acid solution A was uniformly applied so that the thickness after curing was 18.6 μm. The thickness (L1) of the first polyimide layer was 3.2 μm, the thickness (L) of the entire insulating resin layer was 25 μm, and the ratio (L / L1) was 7.8. No bubbling was observed, and no curling of the polyimide film was observed after copper foil etching. The dimensional change rate was "OK".

[Example 22]
The polyamic acid solution E to be the first and third polyimide layers was uniformly applied so that the thickness after curing was 1.7 μm, and the polyamic acid solution A to be the second polyimide layer was cured. That the uniform thickness is 22 μm, and that the temperature rise time from 130 ° C. to 360 ° C. after applying the polyamic acid solution A and the polyamic acid solution E to be the third polyimide layer is 1 / A metal-clad laminate 26 was prepared in the same manner as in Example 19 except that the length was shortened to 3. The thickness (L1) of the first polyimide layer was 1.7 μm, the thickness (L) of the entire insulating resin layer was 25.4 μm, and the ratio (L / L1) was 14.9. No bubbling was observed, and no curling of the polyimide film was observed after copper foil etching. The dimensional change rate was “good”.

[Example 23]
The polyamic acid solution E to be the first polyimide layer and the third polyimide layer was uniformly applied so that the thickness after curing was 1.8 μm, and the polyamic acid solution A to be the second polyimide layer was cured. That the uniform thickness is 22 μm, and that the temperature rise time from 130 ° C. to 360 ° C. after applying the polyamic acid solution A and the polyamic acid solution E to be the third polyimide layer is 1 / A metal-clad laminate 27 was prepared in the same manner as in Example 19 except that the length was shortened to 3. The thickness (L1) of the first polyimide layer was 1.8 μm, the thickness (L) of the entire insulating resin layer was 25.6 μm, and the ratio (L / L1) was 14.2. No bubbling was observed, and no curling of the polyimide film was observed after copper foil etching. The dimensional change rate was “good”.

[Example 24]
The polyamic acid solution E to be the first polyimide layer and the third polyimide layer was uniformly applied so that the thickness after curing was 2.2 μm, and the polyamic acid solution A to be the second polyimide layer was cured. That the uniform thickness is 20 μm and that the temperature rise time from 130 ° C. to 360 ° C. after applying the polyamic acid solution A and the polyamic acid solution E to be the third polyimide layer is 1 / A metal-clad laminate 28 was prepared in the same manner as in Example 19 except that the length was shortened to 3. The thickness (L1) of the first polyimide layer was 2.2 μm, the thickness (L) of the entire insulating resin layer was 24.4 μm, and the ratio (L / L1) was 11.1. No bubbling was observed, and no curling of the polyimide film was observed after copper foil etching. The dimensional change rate was “good”.

[Example 25]
The polyamic acid solution E to be the first polyimide layer and the third polyimide layer was uniformly applied so that the thickness after curing was 2.4 μm, and the polyamic acid solution D to be the second polyimide layer was applied. A metal-clad laminate 29 was prepared in the same manner as in Example 19, except that the composition was uniformly coated so that the thickness after curing was 20.2 μm. The thickness (L1) of the first polyimide layer was 2.4 μm, the thickness (L) of the entire insulating resin layer was 25 μm, and the ratio (L / L1) was 10.4. No bubbling was observed, and no curling of the polyimide film was observed after copper foil etching. The dimensional change rate was “good”.

[Example 26]
The polyamic acid solution F to be the first polyimide layer and the third polyimide layer was uniformly applied so that the thickness after curing was 2.7 μm, and the polyamic acid solution D to be the second polyimide layer was applied. A metal-clad laminate 30 was prepared in the same manner as in Example 19 except that the composition was uniformly coated so that the thickness after curing was 20 μm. The thickness (L1) of the first polyimide layer was 2.7 μm, the thickness (L) of the entire insulating resin layer was 25.4 μm, and the ratio (L / L1) was 9.4. No foaming was confirmed, and no curling of the polyimide film was observed after copper foil etching. The dimensional change rate was “good”.

[Example 27]
The polyamic acid solution G to be the first polyimide layer and the third polyimide layer was uniformly applied so that the thickness after curing was 3.2 μm, and the polyamic acid solution D to be the second polyimide layer was applied. A metal-clad laminate 31 was prepared in the same manner as in Example 19 except that the composition was uniformly coated so that the thickness after curing was 19 μm. The thickness (L1) of the first polyimide layer was 3.2 μm, the thickness (L) of the entire insulating resin layer was 25.4 μm, and the ratio (L / L1) was 7.9. No bubbling was observed, and no curling of the polyimide film was observed after copper foil etching. The dimensional change rate was "OK".

[Example 28]
The polyamic acid solution E was uniformly applied onto a 12 μm-thick electrolytic copper foil so that the thickness after curing was 2.0 μm, and then the solvent was removed at 120 ° C. After the polyamic acid solution A was uniformly applied thereon so that the thickness after curing was 50 μm, the solvent was removed at 120 ° C. for 3 minutes. Further, a polyamic acid solution E was evenly applied thereon so that the thickness after curing was 2.0 μm, the solvent was removed at 120 ° C., and the temperature was raised stepwise from 120 ° C. to 360 ° C. Was removed and imidized to obtain a single-sided metal-clad laminate 28B on which the first polyimide layer was formed. The polyimide layer of the obtained single-sided metal-clad laminate 28B was subjected to corona treatment at 120 W · min / m ² . Next, a polyamic acid solution A to be the second polyimide layer is evenly applied thereon so that the thickness after curing is 50 μm, and the solvent is removed, and then a third polyimide layer is formed thereon. The polyamic acid solution E was uniformly applied so that the thickness after curing would be 2.0 μm, and dried by heating at 120 ° C. for 3 minutes to remove the solvent. Then, the temperature was raised stepwise from 130 ° C. to 360 ° C. for imidization to prepare a single-sided metal-clad laminate 28. The thickness (L1) of the first polyimide layer was 54 μm, the thickness (L) of the entire insulating resin layer was 106 μm, and the ratio (L / L1) was 1.96. No bubbling was observed, and no curling of the polyimide film was observed after copper foil etching. The dimensional change rate was “good”.

[Example 29]
Other than that the polyamic acid solution E for forming the two layers of the first polyimide layer and the polyamic acid solution E for forming the third polyimide layer were uniformly applied so that the thickness after curing was 10 μm, respectively. A single-sided metal-clad laminate 29 was prepared in the same manner as in Example 28. The thickness (L1) of the first polyimide layer was 70 μm, the thickness (L) of the entire insulating resin layer was 130 μm, and the ratio (L / L1) was 1.86. No foaming was confirmed, and no curling of the polyimide film was observed after copper foil etching. The dimensional change rate was “good”.

[Example 30]
The polyamic acid solution E for forming the two layers of the first polyimide layer and the polyamic acid solution E for forming the third polyimide layer were respectively designated as polyamic acid solutions F so that the thickness after curing would be 2.0 μm. To the single-sided metal-clad laminate 30 in the same manner as in Example 28, except that the polyamic acid solution B to be the second polyimide layer was evenly applied so that the thickness after curing was 50 μm. Was prepared. The thickness (L1) of the first polyimide layer was 54 μm, the thickness (L) of the entire insulating resin layer was 106 μm, and the ratio (L / L1) was 1.96. No bubbling was observed, and no curling of the polyimide film was observed after copper foil etching. The dimensional change rate was “good”.

[Example 31]
Other than that the polyamic acid solution F for forming the two layers of the first polyimide layer and the polyamic acid solution F for the third polyimide layer were uniformly applied so that the thickness after curing was 10 μm, respectively. A single-sided metal-clad laminate 31 was prepared in the same manner as in Example 30. The thickness (L1) of the first polyimide layer was 70 μm, the thickness (L) of the entire insulating resin layer was 130 μm, and the ratio (L / L1) was 1.86. No bubbling was observed, and no curling of the polyimide film was observed after copper foil etching. The dimensional change rate was “good”.

Comparative Example 5
When a metal-clad laminate 32 was prepared in the same manner as in Example 19 except that the corona treatment was not performed, curling of the polyimide film was confirmed after etching the copper foil.

Comparative Example 6
When a metal-clad laminate 33 was prepared in the same manner as in Example 20 except that no corona treatment was performed, curling of the polyimide film was confirmed after etching the copper foil.

Comparative Example 7
When a metal-clad laminate 34 was prepared in the same manner as in Example 21 except that the corona treatment was not performed, curling of the polyimide film was confirmed after etching the copper foil.

Comparative Example 8
Foaming was confirmed when the metal-clad laminate 35 was prepared in the same manner as in Example 22 except that the corona treatment was not performed.

Comparative Example 9
When the metal-clad laminate 36 was prepared in the same manner as in Example 23 except that the corona treatment was not performed, foaming was confirmed.

Comparative Example 10
When the metal-clad laminate 37 was prepared in the same manner as in Example 24 except that the corona treatment was not performed, foaming was confirmed.

  Although the embodiments of the present invention have been described above in detail for the purpose of illustration, the present invention is not limited to the above embodiments.

  Reference numeral 10 ... Metal layer, 10A ... Metal foil, 20 ... First polyimide layer, 20A ... First polyamide resin layer, 30 ... Second polyimide layer, 30A ... Second polyamide resin layer, 40 ... Insulating resin layer, 100 ... Metal-clad laminate

Claims (4)

A method for producing a metal-clad laminate comprising an insulating resin layer including a plurality of polyimide layers, and a metal layer laminated on at least one surface of the insulating resin layer,
The following steps 1 to 5:
Step 1) A step of forming a single layer or a plurality of layers of the first polyamide resin layer by laminating a solution of a polyamic acid on the metal layer.
Step 2) a step of imidizing the polyamic acid in the first polyamide resin layer to form a first polyimide layer composed of a single layer or a plurality of layers,
Step 3) a step of performing a surface treatment on the surface of the first polyimide layer,
Step 4) a step of applying a solution of a polyamic acid onto the first polyimide layer to form a single layer or a plurality of layers of the second polyamide resin layer,
Step 5) The polyamic acid in the second polyamide resin layer is imidized to form a second polyimide layer composed of a single layer or a plurality of layers, and the first polyimide layer and the second polyimide layer are separated from each other. A step of forming the laminated insulating resin layer,
Including,
The thickness (L1) of the first polyimide layer is in the range of 0.5 μm or more and 100 μm or less, and the thickness (L) of the entire insulating resin layer is in the range of 5 μm or more and less than 200 μm, and The method for producing a metal-clad laminate, wherein the ratio (L / L1) with L1 is in the range of more than 1 and less than 400.   The method for producing a metal-clad laminate according to claim 1, wherein the polyimide constituting the layer in contact with the metal layer in the first polyimide layer is a thermoplastic polyimide. Moisture permeability of the metal layer, the thickness 25 [mu] m, when ^{25 ℃, 100g / m 2 /} 24hr or less method for producing a metal-clad laminate according to claim 1 or 2. A method of manufacturing a circuit board, comprising a step of processing a wiring circuit of the metal layer of the metal-clad laminate manufactured by the method according to claim 1.

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