JPH01268778A - Hot-melt adhesive, polyimide film with said adhesive layer and printed circuit board therefrom - Google Patents

Abstract

PURPOSE:To provide the title adhesive, comprising a polymer constituted of a specific recurring unit, capable of hot-melt adhesion in a short time, giving high adhesive force to high temperatures, small in deterioration even left to stand at elevated temperatures, useful for application on printed circuit boards etc. CONSTITUTION:The objective adhesive comprising a polymer constituted of recurring unit of formula I [R1-R4 are each H, lower alkoxy or halogen; X is bond, -O-, -S-, >C=O, -SO2-, >S=O, of formula II, III or IV (R5 and R6 are each H, lower alkyl, trifluoromethyl, trichloromethyl or phenyl), X may differ between each recurring unit; Y is of formula V or VI (Ar is aromatic divalent group; Ar' is aromatic trivalent group), Y may differ between each recurring unit].

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a hot melt adhesive, a sheet-like core hot melt adhesive, a polyimide film with a hot melt adhesive layer provided with the hot melt adhesive layer, A flexible printed circuit board formed by adhering a polyimide film and a metal foil through the hot melt adhesive layer; and a metal-based printed circuit formed by adhering a metal plate and metal foil through the hot melt adhesive layer. related to the board for use.

(Prior Art) Currently, flexible printed circuit boards are manufactured by bonding a polyimide film and a metal foil through an insulating adhesive layer. Metal-based printed circuit boards with excellent heat dissipation properties are manufactured by bonding a metal plate, such as an aluminum plate or a steel plate, to a metal foil via an insulating adhesive layer. In these fields of electronics, materials with excellent high-temperature properties and workability are required.

The insulating adhesive layer mentioned above is also heat resistant.

There is a need for materials that have excellent adhesive strength and can be bonded in a short time.

Epoxy-based adhesives have traditionally been used as adhesives,
Modified epoxy resins, phenolic resins, acrylic resins, and the like have a drawback of poor heat resistance.

On the other hand, polyimide resins are known as resins with excellent heat resistance. However, polyimide resin is insoluble and unfusible, making it unsuitable for use as an adhesive.
Rather, the precursor, polyamic acid, must be used in the form of a solution in a specific solvent, and then the solvent must be removed and imidized. However, in this case, voids are likely to be generated due to condensed water during desolvation and imidization, and imidization requires high temperatures and long periods of time, so there are many restrictions on its use.

(Problems to be Solved by the Invention) An object of the present invention is to provide a hot melt adhesive material that has excellent heat resistance and adhesive strength and is capable of melt bonding (hot melt bonding). An object of the present invention is to provide a printed circuit board with excellent heat resistance by using the hot melt adhesive to bond a polyimide film and a metal to a metal foil.

(Means for Solving the Problems) The present invention relates to a hot melt adhesive comprising a polymer having a repeating unit represented by the following formula (11).

[In the formula, R1, R4, Rs, and R4 each independently represent hydrogen, a lower alkyl group, a lower alkoxy group, or a halogen, and X is a bond, -〇-, -S-, -C-.

R4 (where & and R4 each independently represent hydrogen, a lower alkyl group, a trifluoromethyl group, a trichloromethyl group, or a phenyl group) X is a repeating unit that is an aromatic divalent group, and Ar' is an aromatic group. Y (representing a trivalent group of the same group) may be different for each repeating unit. [Such a polymer in the present invention is an aromatic dicarboxylic acid or its reactive derivative and/or an aromatic tricarboxylic acid or its reactive derivative and the general formula (ff) (in the formula, e R1 * R1e R4 and R4 are each independently represents hydrogen, a lower alkyl group, a lower alkoxy group, or a halogen, and X is a bond, -o-, -s +, -C
-tm & and - each independently represent hydrogen or a lower alkyl group.

(represents a tri2-fluoromethyl group, trichloromethyl group or phenyl group).

It is obtained by polycondensing aromatic diamines represented by:

The aromatic dicarboxylic acid in the present invention has two carboxyl groups bonded to an aromatic nucleus. of course,
This aromatic ring may have a hetero ring introduced therein, and the aromatic fRs are alkylene.

It may be bonded with oxygen, carbonyl group, etc.

Furthermore, in the aromatic ring, for example, alkoxy, allyloxy,
Substituents that do not participate in the condensation reaction, such as alkylamino and halogen, may be introduced. The aromatic dicarboxylic acid mentioned above is terephthalic acid.

Isophthalic acid, diphenyl ether dicarboxylic acid-44
', diphenylsulfonedicarboxylic acid 4.4'.

Examples include diphenyldicarboxylic acid-4,4' and naphthalenedicarboxylic acid-1,5.

Terephthalic acid and isophthalic acid are preferred because they are easily available. Further, the above-mentioned reactive derivatives of aromatic dicarboxylic acids include dichlorides, dichlorides, diesters, etc. of the aromatic dicarboxylic acids.

The aromatic tricarboxylic acid in the present invention has three carboxyl groups bonded to the aromatic group, and two of the three carboxyl groups are bonded to adjacent carbon atoms. Of course, this aromatic ring may have a hetero ring introduced therein, or each of the nine aromatic rings may be bonded to an alkylene, oxygen, carbonyl group, or the like. Furthermore, a substituent that does not participate in the condensation reaction, such as alkoxy, allyloxy, alkylamino, or halogen, may be introduced into the aromatic ring. Examples of aromatic tricarboxylic acids include:

trimellitic acid, 3.3.4'-benzophenonetricarboxylic acid, 2. &4'-diphenyltricarboxylic acid.

2.3.5-hyridinetricarboxylic acid, 3,4.4'-
Penzanilide tricarboxylic acid, 1,4,5-naphthalenetricarboxylic acid, 2'-methoxy-3,4,4'-diphenyl ethertricarboxylic acid, τ-chlorobenzanilide 3,44'-)dicarboxylic acid, etc. can. Further, the reactive derivative of the aromatic tricarboxylic acid means an acid anhydride, halide, ester, amide, ammonium salt, etc. of the aromatic tricarboxylic acid.

Examples of these include trimellitic anhydride, trimellitic anhydride monochloride, 1,4-dicarboxy-
3-N,N-dimethylcarbamoylbenzene, 1.4-
Dicarbomethoxy 3-carboxybenzene, 1.4-
Dicarboxy-3-carbophenoxybenzene, 46-
Dicarpoxy 3-carbomethoxypyridine.

1.6-dicarpoxy 5-carbamoylnaphthalene,
The above aromatic tricarboxylic acids and ammonia.

Examples include ammonium salts consisting of dimethylamine, triethylamine, etc. Among these, trimellitic anhydride and trimellitic anhydride monochloride are preferred.

As the aromatic diamine represented by formula (II) above, 2-bis(4-(4-aminophenoxy)phenyl)furopane, λ2-bis[3-methyl-4-(4-aminophenoxy)phenyl ] Propane, 2.2-bis(4
-(4-aminophenoxy)phenylcobutane, 2
．． 2-bis[3-methyl-4-(4-aminophenoxy)phenylcobutane.

2.2-bis[3,5-dimethyl-4-(4-aminophenoxy)phenylcobutane, λ2-bis[tortoise 5-dibromo-4-(4-aminophenoxy)phenylcobutane, 1,1,1 ,3,3.3-hexafluoro-2,
2-bis[3-methyl-4-(4-aminophenoxy)
phenyl]furopane, 1.1-bis[4-(4-aminophenoxy)phenylcocyclohexane, 1.1-bis(4-(4-aminophenoxy)phenylcocyclopenkune, bis(4-(4-aminophenoxy)phenyl) Phenoxy) phenyl]
Sulfone, bis(4-(4-aminophenoxy)phenylconythyl, bis(4-(3-aminophenoxy)phenyl)sulfone, 4.4'-carbonylbis(p-phenyleneoxy)dianiline, 4.4'- Bis(4-aminophenoxy)biphenyl, etc. Among these, bis(2-bis(:4-(4-7minophenoxy)phenyl)propane is preferred. Mixtures of the above diamines may be used if necessary. .

Furthermore, in the present invention, known diamino acids such as 4,4'
-Diaminodiphenyl ether, 4,4'-diaminonephenylmethane, 44'-diaminodiphenylsulfone, metaphenylenediamine, hyherazine, hexamethylenediamine, heptamethylenediamine, tetramethylenediamine, p-xylylenediamine, m-xylylenediamine , 3-methylhebutamethylenediamine, 1.3
-bis(3-aminopropyl)tetramethyldisiloxane, etc. can be used in combination. The ratio of these cyamines to the total diamines is preferably 30 molti or less. If this ratio exceeds 30 molt, thermal stability or thermal meltability tends to deteriorate.

In the present invention, the acid component such as aromatic dicarboxylic acid or its reactive derivative and/or aromatic tricarboxylic acid or its reactive derivative is 80 to 12% of the total amount of diamine.
It is preferable to use 0 mole, and preferably 95 to 105 mole per 1%. When equimolar amounts of these are used, a product with a high molecular weight can be obtained. If the amount of the acid component is too large or too small relative to the diamine, the molecular weight tends to decrease and mechanical strength, heat resistance, etc. tend to decrease.

In one reaction in the present invention, the method already used for the reaction between an amine and an acid can be employed, and various conditions can also be adopted.

It is not particularly limited.

aromatic dicarboxylic acid or its reactive derivative and/or
Alternatively, known methods can be used for the polycondensation reaction between aromatic tricarboxylic acid attachment or its reactive derivative and diamine.

Use two or more aromatic diamines.

Alternatively, by using two or more aromatic dicarboxylic acids or reactive derivatives thereof, or two or more aromatic tricarboxylic acids or reactive derivatives thereof, the general formula +1
Polymers having different repeating units represented by 1 can be obtained.

Further, by using an aromatic dicarboxylic acid or a reactive derivative thereof in combination with an aromatic tricarboxylic acid or a reactive derivative thereof, a polymer having different repeating units represented by the above-mentioned general 2 (1) can be obtained.

The polymer preferably has a reduced viscosity of 0.2 to 0.2 dJ/9 at 30°C in a 0.2% by weight dimethylformamide solution. If the reduced viscosity is too small, the heat resistance 9 mechanical strength tends to decrease, and if it is too thick, the heat meltability tends to decrease.

It is effective to form the adhesive of the present invention into a sheet in advance and use it as a sheet adhesive. 9 The adhesive of the present invention can also be used as a film-like adhesive for fiber-reinforced glass obtained by impregnating a thin cloth mat made of fibers with excellent heat resistance, such as glass fiber, in the form of a so-called festival dissolved in a solvent and drying it. can. The powder of the adhesive of the present invention can also be used by pressure bonding.

The face of the adhesive of the present invention can be applied to an adherend, dried, and heat-melted and pressed to another adherend.

The hot-melt adhesive face of the present invention is coated on one side of a polyimide film and then dried on both sides.The hot-melt adhesive layer-coated polyimide film is then heat-melted and pressure-bonded with metal foil to produce flexible printed circuit boards, etc. It is particularly effective for manufacturing.

Heat melt compression bonding is performed at a temperature of 50 to 400℃ and a temperature of 1 to 1000℃.
It is preferable to pressurize for 1 second to 30 minutes at a pressure of 10 to 500 ka/cm at a temperature of 200 to 350°C.
cx? It is more preferable to pressurize at a pressure of 10 seconds to 10 minutes. 50-200 kg/at a temperature of 250-330℃
It is particularly preferable to apply pressure at a pressure of 30 seconds to 1 minute.

Furthermore, the adhesive of the present invention includes antimony dioxide.

Flammable inorganic compounds such as aluminum hydroxide and barium borate, silica, alumina, mica, titanium oxide, zirconia, calcium silicate, magnesium hydroxide, magnesium oxide, iron oxide, calcium carbonate, silicon carbide, boron nitride, silver powder, Gold powder.

An inorganic filler such as copper powder or nickel powder may be contained in an amount of 70% by weight or less based on the total amount of the adhesive.

When these inorganic fillers exceed 70% by weight,
Adhesive flow tends to decrease and adhesive strength decreases. Furthermore, fillers, stabilizers, surfactants, solvents, etc. other than these may be included depending on the purpose.

Examples of the metal foil in the present invention include steel foil and aluminum foil.

Metal plates in the present invention include aluminum plates, steel plates,
Examples include titanium plates.

A flexible printed circuit board formed by bonding a polyimide film and a metal foil through a hot melt adhesive layer made of the hot melt adhesive of the present invention is useful.

Also useful is a metal paste printed circuit board formed by bonding a metal plate and a metal foil through a real melt adhesive layer made of the hot melt adhesive of the present invention.

(Example) Next, the present invention will be explained with reference to Examples, but the present invention is not limited in any way by these Examples.

Example 1 2.2-bis[4-(4-aminophenoxy)phenyl]propane 2059 (0.5 mol) was added to a four-loaf flask equipped with a thermometer, a stirrer, and a nitrogen inlet tube with a 9-fraction head under nitrogen. and dissolved in 705 g of N-methyl-2-pyrrolidone. This solution was cooled to -10°C, and at this temperature trimellitic anhydride monochloride 105.39 (0.5
mol) was added so that the temperature dangerously exceeded 15°C. Once the trimellitic anhydride monochloride was dissolved, triethylamine 769 was added so that the temperature did not exceed 5°C.

503 g of N-methyl-2-pyrrolidone was added.

After stirring at room temperature for 1 hour, the reaction was carried out at 190°C for 9 hours to complete imidization.

The resulting reaction solution was poured into methanol to isolate polymer 9. After drying this, it was again dissolved in N,N-dimethylformamide, poured into methanol to purify the polyamideimide polymer, and dried under reduced pressure.

Reduced viscosity (ηsp/c) of this polymer (measured in a 0.2% by weight solution of N,N-dimethylformamide at 30°C.

The same applies below) is 0.89 di/g.

The obtained polymer powder was dissolved in N,N-dimethylformamide to make a 25% solution and placed on a glass plate at a thickness of 1cI5 with an IQ of Oμm. 100℃-t' 1 hour ISJ'
After drying, remove the glass plate and fix it on an iron frame.

It was dried at 250° C. for 1 hour to obtain a sheet with a thickness of 25 μm.

The obtained sheet was placed between a 2cm thick aluminum plate and a 35μm thick aluminum plate.
sandwiched between steel foils and heated in a compression molding machine.

Pressure was applied for 1 minute at a temperature of 300° C. and a pressure of 20 kg/cm” to obtain a metal base steel clad plate.

The characteristics are shown in Table 1.

Example 2 147.69 (0,36
), 9.929 (0.04 mol) of 1,3-bis(aminopropyl)tetramethyldisiloxane, and 34.89 (0.6 mol) of propylene oxide were added, and N,N-
Dissolved in 564 g of dimethylacetamide. The solution was cooled to 0°C and at this temperature 84.29 (0.4 mol) of trimellitic anhydride monochloride was added such that the temperature did not exceed 5°C. After stirring at room temperature for 3 hours, acetic anhydride 2
009. Pyridine 509 was added and stirring was continued at 60°C for one day and night. The obtained reaction solution was isolated and purified in the same manner as in Example 1. The reduced viscosity of this polyamideimide polymer is 0.
It was 73 di/n.

A sheet was produced in the same manner as in Example 1, and a metal base steel clad plate was obtained in the same manner as in Example 1 using this sheet as a heat-resistant adhesive.

The characteristics are shown in Table 1.

Example 3 2-bis[4-(4-7minophenoxy)phenyl]propane zosg (o, s mol) was added to a four-bottle flask equipped with a thermometer, stirrer, nitrogen inlet tube, and condenser under nitrogen.
, propylene oxide 69.8 s (1,2 mol)
and dissolved in N-methyl-2-pyrrolidone tzoog. The solution was cooled to -5°C and at this temperature 101.59 (0.5 mol) of isophthalic dichloride was added such that the temperature did not exceed 20°C. Stirring was continued for 3 hours at room temperature.

The obtained reaction solution was isolated in the same manner as in Example 1.

Purified. The reduced viscosity of this polyamide polymer is 1, Od
//s and nine.

A sheet was produced in the same manner as in Example 1, and a metal base steel clad plate was obtained in the same manner as in Example 1 using this sheet as a heat-resistant adhesive.

The characteristics are shown in Table 1.

Example 4 In Example 1, 205 g (0.5 mol) of 2,2-bis(4-(4-aminophenoxy)phenyl)propane
A polyamide-imide polymer was obtained in the same manner as in Example 1 except that 2169 (0.5 mol) of 2169 (0.5 mol) of sulfone was added. The resulting polyamide-imide polymer had a reduced viscosity of 0.66 di/g.

A sheet was produced in the same manner as in Example 1.

This sheet was sandwiched between an aluminum plate with a thickness of 2 aw and a steel foil with a thickness of 35 μm, and was pressed with a heating compression molding machine at a temperature of 320°C and a pressure of 20 kg/am for 1 minute to bond the sheet to the metal paste sheet. I got the veneer.

The characteristics are shown in Table 1.

Example 5 The nine polyamideimide polymer powders obtained in Example 1 were dissolved in diethylene glycol dimethyl ether.

A 25% solution and a 50 μm thick polyimide film (
After drying, the solution was applied to Kapton (manufactured by DuPont) to a thickness of 25 μm and heated at 100°C for 30 minutes.

It was dried at 250° C. for 1 hour to obtain a polyimide film with a hot melt adhesive layer. Next, a 35 μm steel foil was placed on the surface of the hot-melt adhesive-layered polyimide film on which the adhesive layer was provided, and a hot-compression molding machine was used.

Pressure was applied for 1 minute at a temperature of 300° C. and a pressure of 10 kg/am” to obtain a flexible steel clad plate.

The characteristics are shown in Table 1.

Example 6 The adhesive sheet obtained in Example 1 was coated with a 50 μm thick polyimide film (Kapton, manufactured by DuPont) and a 35 μm thick polyimide film (Kapton, manufactured by Dupont).
Sandwiched between μm copper foil, heated and compression molded for 30 min.
A flexible steel clad plate was obtained by pressurizing and bonding at a temperature of 0° C. and a pressure of 10 kg/cm” for 1 minute.

The characteristics are shown in Table 1.

Comparative Example 1 Adhesive film glue HC Vyralux (
DuPont's acrylic sheet adhesive) was used in the same manner as in Example 6 at 180°C and 301gf/cm''.
Lamination was carried out for 60 minutes to obtain a flexible steel clad plate.

The characteristics are shown in Table 1.

Comparative example 2 ff7' with thermometer, stirrer, nitrogen introduction tube, and cooling tube
2.2-bis[4-(4-
Aminophenoxyphenyl]propane 2059 (0,
5 mol) and dissolved in 7705 g of N-methyl-2-pyrrolide. Add 1 pyromellitic dianhydride to this solution at room temperature.
109 (0.5 mol) was added and stirring continued for 20 hours.

The polyamic acid face obtained in this way was cast onto a glass plate so that the thickness after drying was 25 μm.
Dry at 0℃ for 1 hour, peel off and fix on a steel frame at 250℃.
Imidization was carried out at 300° C. for 2 hours and at 300° C. for 2 hours to obtain a polyimide sheet.

Using this polyimide sheet as an adhesive, a flexible steel clad plate was obtained by heat-pressing the same composition as in Example 5 at 350° C. and 50 kg/cm” for 1 minute.

The characteristics are shown in Table 1.

Table 1 Characteristics of various steel clad plates These tests were conducted in accordance with JIS C6481r Test Method for Steel Clad Laminates for Printed Circuits.

(Effects of the invention) Since the hot melt adhesive of the present invention is made of a polymer with excellent heat resistance and meltability, it can be heated and melted in a short time, has excellent adhesive strength even at high temperatures, and can be left unattended at high temperatures. There is also less deterioration later.

The hot melt adhesive of the present invention can also be used in advance in the form of a sheet. Furthermore, since it is soluble in solvents, it can be coated and dried on a base material such as a polyimide film in advance, and then heat-melted and bonded to another adherend.

9 Printed circuit boards using the Hositomelt adhesive of the present invention have excellent heat resistance and adhesive strength, and exhibit excellent performance even when exposed to high temperatures.

Claims (1)

[Claims] 1. A hot melt adhesive comprising a polymer having a repeating unit represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) [In the formula, R_1, R_2, R_3, and R_4 each independently represent hydrogen, a lower alkyl group, a lower alkoxy group, or a halogen, and X is a bond, -O-, -S-, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, -SO_2-, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ formula,
There are chemical formulas, tables, etc. ▼ (Here, R_5 and R
_6 each independently represents hydrogen, a lower alkyl group, a trifluoromethyl group, a trichloromethyl group, or a phenyl group) X may be different for each repeating unit, and Y is ▲ formula,
There are chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (Here, Ar represents an aromatic divalent group, Ar' represents an aromatic trivalent group) It may be different for each repeating unit. 2. The hot melt adhesive according to claim 1, wherein the repeating unit represented by the general formula (I) is ▲a mathematical formula, a chemical formula, a table, etc.▼. 3. The hot melt adhesive according to claim 1, wherein the repeating unit represented by the general formula (I) is ▲a mathematical formula, a chemical formula, a table, etc.▼. 4. The hot melt adhesive according to claim 1, 2 or 3, which is in the form of a sheet. 5. The following general formula (
A polyimide film with a hot melt adhesive layer comprising a polymer having a repeating unit represented by I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) [In the formula, R_1, R_2, R_3, and R_4 each independently represent hydrogen, a lower alkyl group, a lower alkoxy group, or a halogen, and X is a bond, -O-, -S-, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, -SO_2-, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ formula,
There are chemical formulas, tables, etc. ▼ (Here, R_5 and R
_6 each independently represents hydrogen, a lower alkyl group, a trifluoromethyl group, a trichloromethyl group, or a phenyl group) X may be different for each repeating unit, and Y is ▲ formula,
There are chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (Here, Ar represents an aromatic divalent group, Ar' represents an aromatic trivalent group) It may be different for each repeating unit. [6] The polyimide film with a hot-melt adhesive layer according to claim 5, wherein the repeating unit represented by the general formula (I) is ▲a mathematical formula, a chemical formula, a table, etc.▼. 7. The polyimide film with a hot melt adhesive layer according to claim 5, wherein the repeating unit represented by the general formula (I) is ▲a mathematical formula, a chemical formula, a table, etc.▼. 8. Polyimide film and metal foil are combined using the following general formula (I
) A flexible printed circuit board adhered via a hot melt adhesive layer containing a polymer having repeating units represented by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R_1, R_2, R_3, and R_4 each independently represent hydrogen, a lower alkyl group, a lower alkoxy group, or a halogen, and X is a bond, -O-, -S- , ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, -SO_2-, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ formula,
There are chemical formulas, tables, etc. ▼ (Here, R_5 and R
_6 each independently represents hydrogen, a lower alkyl group, a trifluoromethyl group, a trichloromethyl group, or a phenyl group) X may be different for each repeating unit, and Y is ▲ formula,
There are chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (Here, Ar represents an aromatic divalent group, Ar' represents an aromatic trivalent group) It may be different for each repeating unit. [9] The flexible printed circuit board according to claim 8, wherein the repeating unit represented by the general formula (I) is ▲A mathematical formula, a chemical formula, a table, etc.▼ ▲A mathematical formula, a chemical formula, a table, etc.▼ 10. The flexible printed circuit board according to claim 8, wherein the repeating unit represented by the general formula (I) is ▲a mathematical formula, a chemical formula, a table, etc.▼. 11. A metal-based printed circuit board formed by adhering a metal plate and a metal foil through a hot-melt adhesive layer containing a polymer having a repeating unit represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) [In the formula, R_1, R_2, R_3, and R_4 each independently represent hydrogen, a lower alkyl group, a lower alkoxy group, or a halogen, and X is a bond, -O-, -S-, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, -SO_2-, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ formula,
There are chemical formulas, tables, etc. ▼ (Here, R_5 and R
_6 each independently represents hydrogen, a lower alkyl group, a trifluoromethyl group, a trichloromethyl group, or a phenyl group) X may be different for each repeating unit, and Y is ▲ formula,
There are chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (Here, Ar represents an aromatic divalent group, Ar' represents an aromatic trivalent group) It may be different for each repeating unit. 12. The metal-based printed circuit board according to claim 11, wherein the repeating unit represented by the general formula (I) is ▲a mathematical formula, a chemical formula, a table, etc.▼. 13. The metal-based printed circuit board according to claim 11, wherein the repeating unit represented by the general formula (I) is ▲a mathematical formula, a chemical formula, a table, etc.▼.