JP5310345B2 - Laminated body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminate which hardly causes expansion and contraction at a high temperature and retains a well-balanced strength bearing weight or the like. <P>SOLUTION: The laminate is obtained by laminating a plurality of polyimide films obtained by reacting aromatic tetracarboxylic acids with aromatic diamines having benzoxazole skeleton without allowing an adhesive layer to intervene between the films, has a thickness of 10 &mu;m or more and has a linear expansion coefficient in the planar direction in the range of -5 ppm/&deg;C to +7 ppm/&deg;C. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a polyimide film laminate, and more particularly to a polyimide film laminate having a low linear expansion coefficient comparable to a ceramic material.

Polyimide films have very little change in physical properties over a wide temperature range from −269 ° C. to 300 ° C., and therefore, applications and uses in the electric and electronic fields are expanding. In the electric field, for example, it is used for coil insulation of vehicle motors, industrial motors, etc., insulation of aircraft electric wires and superconducting wires. On the other hand, in the electronic field, for example, it is used as a constituent material for a flexible printed circuit board, a base film of a film carrier for semiconductor mounting, a burn-in board or a built-up multilayer wiring board. Thus, the polyimide film is widely used in the electrical and electronic fields as a highly reliable film among various functional polymer films.
Conventionally, ceramic has been used as a material for base materials of electronic components such as information communication equipment (broadcast equipment, mobile radio, portable communication equipment, etc.), radar, high-speed information processing devices, and the like. A base material made of ceramic has heat resistance, and can cope with a recent increase in the frequency band of information communication equipment (reaching the GHz band). However, ceramics are not flexible and cannot be thinned, so the fields that can be used are limited.
For this reason, studies have been made to use a film made of an organic material as a base material for an electronic component, and a film made of polyimide and a film made of polytetrafluoroethylene have been proposed. A film made of polyimide is excellent in heat resistance and has an advantage that the film can be thin because it is tough.

These polyimide films generally have a large coefficient of linear expansion, have a significant dimensional change due to a temperature change, and are not suitable for the production of circuits having fine wiring.
The polyimide film is mainly produced by solution casting by casting, and it is difficult to produce a thick film due to its production method, or its productivity is extremely inferior. For this reason, it has been proposed that thermoplastic polyimide is bonded to a normal polyimide film with a heating laminator or a heating press device, but there are problems of poor heat resistance and increased cost.

Attempts have also been made to provide other structural reinforcements on the polyimide film via an adhesive layer such as a thermoplastic resin. For example, a polyimide molded body in which a thin amorphous polyimide is laminated on the surface of a crystalline polyimide molded body (see Patent Document 1) has been proposed. Although these are satisfactory in structural improvement, a thermoplastic resin is proposed. Because of its low heat resistance, it had a tendency to ruin the heat resistance of the folded polyimide film.
As an improvement, a polyimide film laminate has been proposed that comprises at least two plasma surface-treated polyimide films laminated and thermocompression bonded, and the peel strength between the films is 0.3 kgf / cm or more ( Patent Document 2).

Japanese Patent Laid-Open No. 10-058628 JP 2002-234126 A

However, a polyimide film having a low coefficient of linear expansion while maintaining heat resistance has not been proposed so far.
The present invention is intended to simultaneously solve the problems of these conventional techniques, such as delamination of the laminate, or anxiety about thermal expansion due to a high linear expansion coefficient, using a heat-resistant polyimide, It is to provide a laminate without using a polyimide adhesive.

As a result of intensive studies, the inventors of the present invention have laminated a polyimide film using a diamine having a benzoxazole skeleton after plasma treatment, so that the linear expansion coefficient is in a specific range with a low level, and the heat resistance is higher. It discovered that the polyimide laminated body comprised by this was obtained.
That is, the present invention has the following configuration.
(1) A laminate in which a polyimide film obtained by a reaction between an aromatic tetracarboxylic acid and an aromatic diamine having a benzoxazole skeleton is laminated without an adhesive layer, and the thickness is 10 μm or more. A polyimide film laminate having a linear expansion coefficient in the plane direction of −5 ppm / ° C. to +7 ppm / ° C.
(2) The laminate according to (1), wherein the linear expansion coefficient in the thickness direction is a value of 5 times or more the linear expansion coefficient in the plane direction.
(3) The laminate according to the above (1) or (2), wherein the laminate peel strength is 3.0 N / cm or more at the initial stage, and shows a value of 2.0 N / cm or more after the PCT treatment and after the heat treatment.
(4) The laminate according to any one of (1) to (3), wherein the average surface roughness Ra of the peeled surface of the laminate is 10 nm or more.
(5) The laminate according to any one of (1) to (4) above, wherein the surface element ratio O / C of the release surface of the laminate is 0.20 to 0.35 and A / C is less than 0.05. body. (However, O represents oxygen, C represents carbon, A represents an element other than carbon, nitrogen, and oxygen, and the abundance observed by ESCA is 0.1 atom% or more.)

By this invention, the polyimide laminated body of the outstanding performance as shown below can be provided. An aromatic tetracarboxylic acid or a reactive derivative thereof (eg, anhydride and amide-forming derivative) (hereinafter, these may be collectively referred to as aromatic tetracarboxylic acids) and an aromatic diamine having a benzoxazole skeleton or Lamination obtained by laminating polyimide films obtained by reaction with reactive derivatives (eg, amide-forming derivatives) (hereinafter, these may be collectively referred to as aromatic diamines) without using an adhesive layer. This is a polyimide laminate with a thickness of 10 μm or more and a linear expansion coefficient in the plane direction of −5 ppm / ° C. to +7 ppm / ° C., which has low thermal expansion and shrinkage at high temperatures and strength to withstand weight, etc. Is a laminate that is maintained in a well-balanced manner. Therefore, it can be effectively used as a mechanical jig or component at a high temperature or in a device laminate, and has excellent insulation, heat resistance, and heat-resistant dimensional stability, and can solve mechanical problems in handling and the like.
In addition, the laminate of the present invention can be effectively used for a device laminate such as a sensor or circuit, particularly a device laminate such as a sensor or circuit excellent in heat-resistant dimensional stability, without using an adhesive. Can do.

  The polyimide in the polyimide (film) laminate in the present invention is not particularly limited as long as it is a polyimide obtained by a reaction between an aromatic tetracarboxylic acid and an aromatic diamine having a benzoxazole structure (skeleton).

<Aromatic diamines having a benzoxazole structure>
The molecular structure of aromatic diamines having a benzoxazole structure is not particularly limited, and is usually amino (aminophenyl) benzoxazole which may have a substituent, or phenylenebisamino which may have a substituent. Examples include benzoxazole, bisaminobenzoxazolobenzene which may have a substituent, and diaminodiphenylbenzobisoxazole which may have a substituent. Specific examples include the following.

Among these, from the viewpoint of easy synthesis, each isomer of amino (aminophenyl) benzoxazole is preferable, and 5-amino-2- (p-aminophenyl) benzoxazole is more preferable. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, the above “formula 1” to “formula 4”). Each compound described in the above. These diamines may be used alone or in combination of two or more.
In the present invention, the aromatic diamine having the benzoxazole structure is preferably used in an amount of 70 mol% or more of the wholly aromatic diamine.

  In the present invention, as long as it is 30 mol% or less of the wholly aromatic diamine, one or more of the diamines exemplified below may be used in combination. Examples of such diamines include 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, and bis [4- (3-aminophenoxy) phenyl]. Sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 3,3′-diamino Diphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodi Phenyl sulfide, 3,3′-diaminodiphenyl sulfoxide, 3,4′-diaminodiphenyl sulfoxide, 4,4′-diaminodiphenyl sulfoxide, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 4, 4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4 '-Diaminodiphenylmethane, bis [4- (4-aminophenoxy) phenyl] methane, 1,1-bis [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) ) Phenyl] ethane, 1,1-bis [4- (4-aminophenoxy) Phenyl] propane, 1,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,3-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4 -Aminophenoxy) phenyl] propane, 1,1-bis [4- (4-aminophenoxy) phenyl] butane, 1,3-bis [4- (4-aminophenoxy) phenyl] butane, 1,4-bis [ 4- (4-aminophenoxy) phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl] butane, 2- [4- (4-Aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3- Tilphenyl] propane, 2- [4- (4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4- Aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,4- Bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfone Hydroxide, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,3-bis [ 4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 4, 4′-bis [(3-aminophenoxy) benzoyl] benzene, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [4- (3-aminophenoxy) phenyl] propane 3,4′-diaminodiphenyl sulfide, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3- Hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) Phenyl] ethane, bis [4- (3-aminophenoxy) phenyl] sulfoxide, 4,4′-bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [3- (3-amino Phenoxy) benzoyl] diphenyl ether, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethyl) Benzyl) phenoxy] diphenylsulfone, bis [4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4 (4-Aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-fluorophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-methylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-cyanophenoxy) -α, α -Dimethylbenzyl] benzene, 3,3'-diamino-4,4'-diphenoxybenzophenone, 4,4'-diamino-5,5'-diphenoxybenzophenone, 3,4'-diamino- 4,5′-diphenoxybenzophenone, 3,3′-diamino-4-phenoxybenzophenone, 4,4′-diamino-5-phenoxybenzophenone, 3,4′-diamino-4-phenoxybenzophenone, 3,4′- Diamino-5'-phenoxybenzophenone, 3,3'-diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5 '-Dibiphenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone, 4,4'-diamino-5-biphenoxybenzophenone, 3,4'-diamino-4-biphenoxybenzophenone, 3,4'- Diamino-5′-biphenoxybenzophenone, 1,3-bis (3-amino-4-phenoxybenzoyl) benze 1,4-bis (3-amino-4-phenoxybenzoyl) benzene, 1,3-bis (4-amino-5-phenoxybenzoyl) benzene, 1,4-bis (4-amino-5-phenoxybenzoyl) Benzene, 1,3-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,4-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,3-bis (4-amino-5- Biphenoxybenzoyl) benzene, 1,4-bis (4-amino-5-biphenoxybenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzonitrile, and Some or all of the hydrogen atoms on the aromatic ring of the aromatic diamine are halogen atoms, alkyl groups having 1 to 3 carbon atoms, alkoxyl groups, cyano groups, It can be mentioned such as an alkyl group or an aromatic diamine in which a part or all of the hydrogen atoms are substituted with a halogenated alkyl group or an alkoxyl group having 1 to 3 carbons substituted with a halogen atom alkoxyl group.

<Aromatic tetracarboxylic acids>
An aromatic tetracarboxylic acid used in the present invention is preferably an anhydride, and particularly preferably a dianhydride. Specific examples include the following.

  These tetracarboxylic acid anhydrides may be used alone or in combination of two or more.

  In the present invention, one or two or more non-aromatic tetracarboxylic dianhydrides exemplified below may be used in combination as long as they are less than 30 mol% of the total tetracarboxylic dianhydrides. Examples of such tetracarboxylic acid anhydrides include butane-1,2,3,4-tetracarboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, and cyclobutanetetracarboxylic acid. Acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, cyclohex-1-ene-2,3 5,6-tetracarboxylic dianhydride, 3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohexane-3 -(1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride 1-ethylcyclohexane -(1,2), 3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane- 1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2.1] Heptane-2,3,5,6-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane-1 -(2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ', 4'-tetracarboxylic dianhydride, bicyclo [2.2.1] heptane -2,3,5,6-tetracarboxylic dianhydride, Cyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid A dianhydride etc. are mentioned. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

<Solvent>
The solvent used when the polyamic acid is obtained by reacting (polymerizing) the aromatic tetracarboxylic acid and the aromatic diamine is not particularly limited as long as it dissolves both the raw material monomer and the produced polyamic acid. Is preferably a polar organic solvent, such as N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, Examples include hexamethylphosphoric amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, and halogenated phenols. These solvents can be used alone or in combination. The amount of the solvent used may be an amount sufficient to dissolve the monomer as a raw material. As a specific amount used, the weight of the monomer in the solution in which the monomer is dissolved is usually 5 to 40% by weight, The amount is preferably 10 to 30% by weight.

Conventionally known conditions may be applied for the polymerization reaction for obtaining the polyamic acid (hereinafter also simply referred to as “polymerization reaction”). As a specific example, in a temperature range of 0 to 80 ° C., 10 Stirring and / or mixing continuously for minutes to 30 hours. If necessary, the polymerization reaction may be divided or the temperature may be increased or decreased. In this case, the order of adding both monomers is not particularly limited, but it is preferable to add aromatic tetracarboxylic acid anhydrides to the solution of aromatic diamines. The weight of the polyamic acid in the polyamic acid solution obtained by the polymerization reaction is preferably 5 to 40% by weight, more preferably 10 to 30% by weight, and the viscosity of the solution is measured with a Brookfield viscometer (25 ° C.). From the viewpoint of the stability of liquid feeding, it is preferably 10 to 2000 Pa · s, and more preferably 100 to 1000 Pa · s.
The reduced viscosity (ηsp / C) of the polyamic acid in the present invention is not particularly limited, but is preferably 3.0 dl / g or more, more preferably 4.0 dl / g or more. By setting these reduced viscosities, It becomes easy to control the linear expansion coefficient of the obtained polyimide benzoxazole from −10 −5 to +16 +7 (ppm / ° C.).

  Vacuum defoaming during the polymerization reaction is effective for producing a good quality polyamic acid solution. Moreover, you may perform superposition | polymerization by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction. Examples of the end capping agent include compounds having a carbon-carbon double bond such as maleic anhydride. The amount of maleic anhydride used is preferably 0.001 to 1.0 mol per mol of aromatic diamine.

  In order to form a polyimide film to be laminated from a polyamic acid solution obtained by a polymerization reaction, a green film (that is, a self-supporting precursor film) is obtained by coating the polyamic acid solution on a support and drying it. And then imidizing the green film by subjecting it to a heat treatment. Application of the polyamic acid solution to the support includes, for example, casting from a die with a slit and extrusion by an extruder, but is not limited thereto, and conventionally known solution application means can be appropriately used.

  The thickness of the polyimide film (single layer) constituting the laminate in the present invention is not particularly limited, but is preferably 50 μm or less, more preferably 40 μm or less, and further preferably 25 μm or less. From the viewpoint of workability at the time of lamination processing, a preferable lower limit is 3 μm. The in-plane thickness unevenness of these films is preferably 20% or less.

The linear expansion coefficient of the polyimide laminate in the present invention (hereinafter sometimes referred to as CTE) is defined as the linear expansion coefficient of the polyimide laminate in the plane direction of the laminate, and preferably from −5 ppm / ° C. to +7 ppm / ° C. -1.0 ppm / ° C to +5 ppm / ° C is more preferable.
When CTE exceeds the range of −5 ppm / ° C. to +7 ppm / ° C., the dimension of the laminate expands or contracts when exposed to a predetermined temperature or higher, and the dimensional stability of the laminate does not appear. .
Since the laminate is particularly excellent in dimensional stability against temperature changes, the laminate exhibits excellent characteristics for processing accompanied by temperature changes, fine processing, and lamination with dimensional stable dissimilar materials.
Moreover, in order to control the linear expansion coefficient of a laminated body within the said range, it is necessary to laminate | stack the single film which has a low linear expansion coefficient. As the method, it is important to select aromatic tetracarboxylic acids that can be expected to be highly oriented and aromatic diamines having a benzoxazole structure (skeleton). For aromatic diamines having a benzoxazole structure, amino (aminophenyl) benzoxazole isomers are suitable, and for acid anhydrides, pyromellitic anhydride and 3,3 ′, 4,4′- Biphenyltetracarboxylic anhydride is suitable.

For the formation method of the laminate, a green film (polyimide precursor film) at the time of polyimide film production is laminated and imidized, or the polyimide film surface is subjected to atmospheric pressure (normal pressure) plasma treatment or vacuum plasma treatment. There is a method in which the green film and vacuum press are combined. The method of forming the laminate of the present invention is a method in which polyimide films are plasma treated and the polyimide films are laminated by vacuum pressing or heating and pressing, and at least two polyimide films that have been subjected to plasma surface treatment are laminated. A production method is preferred in which lamination is carried out by heating and pressing for 3 minutes or more at a temperature of at least ° C. and a pressure of at least 20 kg / cm ² .

In the method for producing a laminate of the present invention in which at least two polyimide films subjected to plasma surface treatment are stacked and heated and pressed at a temperature of 150 ° C. or more and a pressure of 20 kg / cm ² or more for 3 minutes or more, the plasma surface treatment method comprises: A known method such as glow discharge can be employed. In order to carry out the plasma surface treatment of the polyimide film preferably, glow discharge is performed by applying a discharge voltage of at least 1,000 volts or more between the electrodes in the internal electrode type low temperature plasma generator, and the polyimide film surface is subjected to a low temperature plasma atmosphere. Contact with. Plasma gases for low temperature plasma treatment include helium, neon, argon, nitrogen, oxygen, air, nitrous oxide, nitrogen monoxide, nitrogen dioxide, carbon monoxide, carbon dioxide, ammonia, water vapor, hydrogen, sulfurous acid gas , Hydrogen cyanide and the like are exemplified, and these can be used alone or in admixture of two or more. In particular, it is preferable to use an oxygen-containing inorganic gas, more preferably carbon dioxide and water vapor, and most preferably carbon dioxide.

The pressure of the gas atmosphere in the apparatus is preferably in the range of 0.001 to 10 Torr, and more preferably 0.1 to 1.0 Torr. Stable glow discharge can be performed by applying electric power of 10 W to 100 KW at a high frequency of, for example, a frequency of 10 KHz to 2 GHz between the discharge electrodes under such a gas pressure. As the discharge frequency band, low frequency, microwave, direct current and the like can be used in addition to high frequency. The low-temperature plasma generator is preferably an internal electrode type, but may be an external electrode type in some cases, and may be either capacitive coupling such as a coil furnace or inductive coupling. The shape of the electrode is not particularly limited, and various shapes such as a flat plate shape, a ring shape, a rod shape, and a cylinder shape are possible, and further, a shape in which the metal inner wall of the processing apparatus is grounded as one electrode may be used. . In order to apply a voltage of 1,000 volts or more between the electrodes and maintain a stable low temperature plasma state, it is necessary to apply an insulating coating having a considerable withstand voltage to the input electrode.
Discharge power density suitable for plasma treatment is preferably in a range of from 5~2000W · min / m ^2, more preferably 10~1500W · min / m ^2. If it is less than 5 W · min / m ² , the modification effect is not sufficient. If it is greater than 2000, surface embrittlement proceeds and a laminate having sufficient strength cannot be obtained.

In the present invention, the surface element ratio of the plasma surface-treated polyimide film used for lamination is preferably O / C of 0.30 to 0.45. When O / C is less than 0.30, the modification effect by the plasma treatment is not sufficient, and when O / C is greater than 0.45, the embrittlement of the surface proceeds and the laminate has sufficient strength. Cannot be obtained.
In addition, A / C is desirably less than 0.05, and a preferred lower limit is 0. (However, A means an element other than carbon, nitrogen, and oxygen, and the abundance observed by ESCA is 0.1 atom% or more.) At 0.05 or more, an element not involved in adhesion is This increases the strength and prevents strong adhesion at the laminated interface. Here, when A / C is less than 0.05, when a plurality of elements other than carbon, nitrogen, and oxygen are included, the total value of the plurality of included elements is 0.05 with respect to carbon. It is less than. Therefore, even if A / C is less than 0.05 for individual elements, if A / C obtained by adding a plurality of elements is 0.05 or more, strong adhesion at the laminated interface is inhibited.

That is, one of the important points in the method for producing the polyimide laminate of the present invention is that the surface of the polyimide film obtained by the reaction of aromatic tetracarboxylic acids and aromatic diamines having a benzoxazole skeleton is laminated. The above plasma processing method is to control the plasma processing conditions so that the surface element ratio O / C is 0.30 to 0.45 and A / C is less than 0.05 at the previous time point. The control becomes possible by adopting.
Moreover, surface element ratio O / C of the peeling surface of the polyimide film which comprises the laminated body of this invention created in this way is 0.20-0.35. In other words, the laminate of the present invention forms a bonding layer having an element ratio O / C of 0.20 to 0.35 in the thickness direction of the laminate. Such a bonding layer is formed as (n-1) layers when n polyimide films are laminated.

  Thus, when plasma-treating the surface of the polyimide film, the film surface to be plasma-treated may be one side, but it is preferable to plasma-treat both sides. The obtained plasma surface-treated polyimide film is obtained by laminating at least two of these and thermocompression bonding without using an adhesive or the like to obtain a laminate. When laminating a plasma surface-treated polyimide film and thermocompression bonding, the thermocompression bonding means is not particularly limited, and a heating roll is used, or a film laminated by cutting between flat hot plates is pressed with a cylinder or the like. You can also.

In thermocompression bonding, heating and pressurization under vacuum (reduced pressure) is preferable from the viewpoint that defects such as bubbles are not easily generated in the obtained laminate. In order to reduce the in-plane pressure unevenness, a mirror plate, a cushion plate, or the like may be used on the top or bottom or inside of the laminate. As the heating and pressing conditions, any conditions can be selected, but from the viewpoint of heat resistance of the obtained laminate, it is necessary to heat and press at 150 ° C. or higher, 180 ° C. or higher and 20 kg / cm ² or higher. It is preferable to heat and press for 3 minutes or more under conditions. What is necessary is just to set suitably the temperature of a lamination process, a pressure, and time according to a layer structure.
The upper limit value of the heating temperature is usually about 400 ° C., and the upper limit value of the pressurizing pressure is usually about 1000 kg / cm ² . Lamination is performed by stacking 2 or more and 4 to 2000 plasma surface-treated polyimide films and thermocompression-bonding to obtain a sheet-like laminate. The thickness of the obtained laminate is preferably 10 μm or more, more preferably 50 μm or more, further 100 μm or more, even more preferably 250 μm or more, and further preferably 500 μm or more, and there is no particular upper limit. By repeating this production method, a laminate of usually 0.2 to 100 mm, preferably 0.5 to 20 mm can be easily obtained.

  In the present invention, the laminate peel strength is 3.0 N / cm or more at the initial stage, after pressure cooker test (PCT) treatment (for example, 121 ° C., 100%, 2 atm, 96 hrs), and heat treatment (for example, 150 It is desirable to show a value of 2.0 N / cm or more after 168 hrs. If the initial peel strength is less than 3.0 N / cm, the adhesive strength between layers is insufficient, and drilling with lasers and drills and external processing such as routers when used in device laminates such as sensors and circuits. Cracks and peeling are likely to occur. In addition, when the peel strength after PCT treatment and heat treatment is less than 2.0 N / cm, when used in a high-temperature or high-humidity environment, cracks and peel will occur against stress due to thermal expansion and humidity expansion with other members. Likely to happen.

  As another method for forming a polyimide molded body, there is a method in which polyimide particles are compression molded. In general, in this method, only a molded body having the same linear expansion coefficient value in the thickness direction and the surface direction can be obtained. One feature of the laminate of the present invention is that a film single film having a linear expansion coefficient in the thickness direction of 5 times or more in the plane direction is laminated so that the linear expansion coefficient in the thickness direction is 5 in the plane direction. It has a value more than double. The linear expansion coefficient in the thickness direction with respect to the surface direction is preferably 5 times or more, and more preferably 10 times or more. By molding such a laminate having anisotropy in the thickness direction and the plane direction, a molded body having low linear expansion in the plane direction can be realized.

  The average surface roughness Ra of the peeled surface after peeling the laminate in the present invention is preferably 10 nm or more, more preferably 15 nm or more, and the upper limit is not particularly limited. When the average surface roughness Ra of the peeled surface is less than 10 nm, the fracture mode between the layers of the laminate is brittle and sufficient adhesion cannot be obtained. In this case, when the outer shape of the laminate is processed, peeling easily proceeds, and the shape retention as the laminate is hindered. When the average surface roughness Ra is 10 nm or more, the interlaminar fracture mode is formed as a very strong laminate represented by cohesive fracture and material fracture. The average surface roughness Ra is a value measured with a direct phase interference microscope VertScan described later, and is equivalent to the arithmetic average roughness (Ra) of JIS B0601-1994.

As for the surface element ratio of the peeling surface which peeled the laminated body in this invention, 0.20-0.35 are desirable for O / C. When the O / C of the peeled surface is less than 0.20, the effect of modifying the film by plasma is not sufficient, and when the O / C is larger than 0.35, strong interface adhesion cannot be obtained. When the O / C is in the range of 0.20 to 0.35, the laminate is destroyed by the simultaneous progress of destruction of the modified layer and the inside of the film by plasma.
A / C is preferably less than 0.05. (However, A means an element other than carbon, nitrogen, and oxygen, and the abundance observed by ESCA is 0.1 atom% or more.) When A / C is 0.05 or more, adhesion is achieved. Since non-participating elements increase, strong adhesion at the laminated interface is hindered.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited by a following example. In addition, the evaluation method of the physical property in the following examples is as follows.

1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone (or N, N-dimethylacetamide) so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. with an Ubbelohde type viscosity tube. (When the solvent used for preparing the polyamic acid solution was N, N-dimethylacetamide, the polymer was dissolved using N, N-dimethylacetamide and measured.)

2. Measurement of the thickness of the polyimide film and the laminate Using a micrometer (Millitron 1245D, manufactured by Finelfu Co., Ltd.), five different points were measured and the average value was expressed.

3. Polyimide film, tensile modulus of tensile strength, tensile breaking strength and tensile breaking elongation of the polyimide film to be measured, cut into strips of 100 mm × 10 mm in the flow direction (MD direction) and the width direction (TD direction), respectively Was used as a test piece. Using a tensile tester (manufactured by Shimadzu Corp., Autograph (registered trademark), model name AG-5000A), tension was applied in each of the MD and TD directions under the conditions of a tensile speed of 50 mm / min and a chuck distance of 40 mm. The elastic modulus, tensile breaking strength and tensile breaking elongation were measured. The number of measured samples is N = 3, and the measurement result indicates an average value thereof.

4). Polyimide film, coefficient of linear expansion (CTE) in the surface direction and thickness direction of the laminate
For the polyimide film to be measured, the stretch rate in the MD direction and the TD direction is measured under the following conditions, and the stretch rate / temperature at intervals of 10 ° C., such as 40-50 ° C., 50-60 ° C., is measured. This measurement was performed up to 450 ° C. Average values of all measured values from 50 ° C. to 400 ° C. were calculated as CTE (average value) in the MD direction and CTE (average value) in the TD direction, respectively. The value in the plane direction of the film surface or laminate is the linear expansion coefficient (CTE) in the plane direction with the average value of the MD value and the TD value, while the value in the thickness direction is the thickness direction. The linear expansion coefficient (CTE). The number of measured samples is N = 3, and the measurement result indicates an average value thereof.
Thermomechanical analyzer: TMA4000S manufactured by Bruker AXS
Sample length: 10mm
Sample width: 2mm
Temperature rise start temperature: 25 ° C
Temperature rise end temperature: 450 ° C
Temperature increase rate: 5 ° C / min
Atmosphere: Argon

5. Surface composition analysis of polyimide film and laminate release surface The oxygen / carbon ratio (O / C ratio) and the silicon / carbon ratio (Si / C ratio) were measured by photoelectron spectroscopy (ESCA). Immediately after the plasma treatment, the polyimide film was fixed on the sample holder with double-sided tape and exhausted sufficiently in the preliminary exhaust chamber. Thereafter, the sample was put into the chamber of the measurement chamber, and the surface composition was analyzed. Mg Kα was used as the X-ray source, and the output was set to 10 kV and 20 mA. The detector has a pass energy of 75 eV and a photoelectron escape angle of 90 degrees. Measurement was performed at a pitch of 0.1 eV, and the measurement time was 200 ms per pitch, and integration was performed 7 times or more. During the measurement, the degree of vacuum in the sample chamber was set to 3 × 10 ⁻⁵ Pa or less. As correction of the peak accompanying charging during measurement, the binding energy value of the main peak of C1s was adjusted to 285.0 eV.
The C1s peak area was determined by drawing the background of the Shirley method in the range of the binding energy 281 to 295 eV, the O1s peak area in the range of 528 to 541 eV, and the Si2p peak area in the range of the binding energy 98 to 109 eV. As the intensity at the two end points when the background was drawn, a value obtained by numerically averaging the intensity at 10 points in the vicinity of each end point was used.
The oxygen / carbon ratio (O / C ratio) is the ratio of the C1s peak area to the O1s peak area, and the silicon / carbon ratio (Si / C ratio) is the ratio of the C1s peak area to the Si2p peak area. It was expressed as an atomic ratio calculated by dividing by the sensitivity correction value. In this example, “ESCA3400” manufactured by Shimazu-Kratos was used as the X-ray photoelectron spectrometer.
In the following examples, A is described as Si. However, A is not limited to Si, and the element ratio can be calculated by analysis similar to the above according to the observed element.

6). Measurement of peel strength of laminate The evaluation of the adhesion of the laminate (evaluation of the adhesion between the films of the laminate structure) is performed immediately after the laminate is formed, by pressure cooker test (PCT) treatment (121 ° C, 100%, After 2 atm, 96 hrs) and after heat treatment (150 ° C., 168 hrs), the peel strength was measured by performing a 180 degree peel test under the following conditions. The number of measured samples is N = 3, and the measurement result indicates an average value thereof.
Testing machine: Autograph AG-IS, manufactured by Shimadzu Corporation
Sample length: 100mm
Sample width: 3mm
Measurement temperature: 25 ° C
Peeling speed: 50mm / min
Atmosphere: Atmosphere

7). Analysis of surface roughness of peeled surface of laminated body Observation method of protrusion on peeled surface of each film of laminated body structure: Surface observation of film using direct phase interference microscope VertScan (manufactured by Ryoka System Co., Ltd.) (mode: wave560M, Observation field of view: 75 × 75 μm ² ) was carried out, and the average surface roughness (Ra) was calculated.

8). The moisture absorption reflow test laminate was tested under the condition of JEDEC (Joint Electron Device Engineering Council) LEVEL 1 (85 ° C./85% RH-168 hr + 245 ° C./3 sec × 3 times). That is, a test sample that was left in a high humidity atmosphere of 85 ° C./85% RH for 168 hours was taken out, and the test immersed in a solder bath at 245 ° C. for 3 seconds was repeated three times. The appearance after the test was inspected and evaluated as ◯ when no peeling, blistering, or discoloration was observed, △ when peeling, blistering, or slight discoloration was observed, and x when peeling, blistering, or discoloration was observed. did. The number of samples measured was N = 3.

[Reference Example 1]
(Preliminary dispersion of inorganic particles)
1.22 parts by mass of amorphous silica spherical particle Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.) and 420 parts by mass of N-methyl-2-pyrrolidone, the wetted part and the infusion pipe are made of austenitic stainless steel SUS316L. The mixture was placed in a container and stirred with a homogenizer T-25 basic (manufactured by IKA Labortechnik) at a rotation speed of 1000 rpm for 1 minute to obtain a preliminary dispersion. The average particle size in the preliminary dispersion was 0.11 μm.

(Preparation of polyamic acid solution)
The reactor was equipped with a nitrogen inlet tube, a thermometer, a stirring rod, and the wetted part and the infusion pipe were made of austenitic stainless steel SUS316L. After purging with nitrogen, 223 parts by mass of 5-amino-2- (p- Aminophenyl) benzoxazole was placed in the reaction vessel. Next, 4000 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, and then 421.2 parts by mass of the previously obtained preliminary dispersion and 217 parts by mass of pyromellitic dianhydride were added. By stirring for 24 hours at ° C., a brown viscous polyamic acid solution A was obtained. The reduced viscosity (ηsp / C) of the polyamic acid solution A was 3.8.

[Reference Example 2]
(Preliminary dispersion of inorganic particles)
7.6 parts by mass of amorphous silica spherical particles Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.) and 390 parts by mass of N-methyl-2-pyrrolidone, the wetted part and the infusion pipe are made of austenitic stainless steel SUS316L. The mixture was placed in a container and stirred with a homogenizer T-25 basic (manufactured by IKA Labortechnik) at a rotation speed of 1000 rpm for 1 minute to obtain a preliminary dispersion.

(Preparation of polyamic acid solution)
Nitrogen introduction pipe, thermometer, liquid contact part of vessel equipped with stirring rod, and infusion piping were replaced with nitrogen in reaction vessel made of austenitic stainless steel SUS316L, and then 200 parts by mass of diaminodiphenyl ether was put into reaction vessel I put it in. Next, after 3800 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, 397.6 parts by mass and 217 parts by mass of pyromellitic dianhydride were added to the preliminary dispersion obtained above. By stirring at 25 ° C. for 5 hours, a brown viscous polyamic acid solution B was obtained. The reduced viscosity (ηsp / C) of the polyamic acid solution B was 3.7.

[Preparation of polyimide film]
The polyamic acid solution obtained in Reference Examples 1 and 2 was coated on a stainless steel endless continuous belt mirror-finished using a die coater (coating width 1240 mm) and dried at 90 to 115 ° C. for 10 minutes. The polyamic acid film that became self-supporting after drying was peeled from the support and cut at both ends to obtain a green film composed of the polyamic acid solutions A and B.
These obtained green films were passed through a pin tenter having a pin sheet in which pins are arranged so that the pin interval is constant when the pin sheets are arranged, and gripped by inserting the end of the film into the pins. The pin sheet interval was adjusted so that the film was not broken and unnecessary tarmi was not generated. It is conveyed so that the final pin sheet spacing is 1140 mm, and the first stage is heated at 170 ° C. for 2 minutes, the second stage at 230 ° C. for 2 minutes, and the third stage 485 for 6 minutes. To allow the imidization reaction to proceed. Then, it cooled to room temperature in 2 minutes, the part where the flatness of the both ends of a film was bad was cut off with the slitter, it wound up in roll shape, and each polyimide film of the film 1-the film 3 which exhibits brown was obtained. The measurement results of the characteristics of the obtained polyimide films 1 to 3 are shown in Table 1.

<Example 1>
A high frequency voltage was applied to an internal electrode type plasma source in a carbon dioxide atmosphere at an atmospheric pressure of 0.2 Torr, a discharge power density (E value) of 25 W · min / m ² , and a polyimide film NO. Both sides of 1 (thickness 38 μm) were plasma treated. Although the discharge power density varies depending on the apparatus, the examples and comparative examples in this specification are implemented using the same apparatus.
Two pieces of this film were cut into 20 cm layers, placed on top and bottom, and 3 mm thick cushion plates made of glass Teflon (registered trademark) were placed on top and bottom, using a vacuum press apparatus at 280 ° C. and 130 kg / cm ^2. The pressure was released after cooling to 100 ° C. and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 76 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test. The laminate was sufficiently resistant to external processing such as router processing and drilling.

<Example 2>
A high frequency voltage was applied to an internal electrode type plasma source in a carbon dioxide atmosphere at an atmospheric pressure of 0.2 Torr, a discharge power density (E value) of 70 W · min / m ² , and a polyimide film NO. Both sides of 1 (thickness 38 μm) were plasma treated.
Two pieces of this film were cut into 20 cm layers, placed on top and bottom, and 3 mm thick cushion plates made of glass Teflon (registered trademark) were placed on top and bottom, using a vacuum press apparatus at 280 ° C. and 130 kg / cm ^2. The pressure was released after cooling to 100 ° C. and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 76 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test. The laminate was sufficiently resistant to external processing such as router processing and drilling.

<Example 3>
A high frequency voltage was applied to an internal electrode type plasma source under a carbon dioxide atmosphere at an atmospheric pressure of 0.2 Torr, and a discharge power density (E value) of 520 W · min / m ² polyimide film NO. Both sides of 1 (thickness 38 μm) were plasma treated.
Two pieces of this film were cut into 20 cm layers, placed on top and bottom, and 3 mm thick cushion plates made of glass Teflon (registered trademark) were placed on top and bottom, using a vacuum press apparatus at 280 ° C. and 130 kg / cm ^2. The pressure was released after cooling to 100 ° C. and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 76 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test. The laminate was sufficiently resistant to external processing such as router processing and drilling.

<Example 4>
A high frequency voltage was applied to an internal electrode type plasma source in a carbon dioxide atmosphere at an atmospheric pressure of 0.2 Torr, and a discharge power density (E value) of 680 W · min / m ² , polyimide film NO. Both sides of 1 (thickness 38 μm) were plasma treated.
Two pieces of this film were cut into 20 cm layers, and a 3 mm thick cushion plate made of glass Teflon (registered trademark) was placed on the top and bottom, using a vacuum press device at 280 ° C. and 130 kg / cm ² . After pressing for 30 minutes, the pressure was released after cooling to 100 ° C., and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 76 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test. The laminate was sufficiently resistant to external processing such as router processing and drilling.

<Example 5>
A high-frequency voltage was applied to an internal electrode type plasma source under a carbon dioxide atmosphere at an atmospheric pressure of 0.2 Torr, and a discharge power density (E value) of 1100 W · min / m ² , polyimide film NO. Both sides of 1 (thickness 38 μm) were plasma treated.
Two pieces of this film were cut into 20 cm layers, placed on top and bottom, and 3 mm thick cushion plates made of glass Teflon (registered trademark) were placed on top and bottom, using a vacuum press apparatus at 280 ° C. and 130 kg / cm ^2. The pressure was released after cooling to 100 ° C. and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 76 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test. The laminate was sufficiently resistant to external processing such as router processing and drilling.

<Example 6>
A high frequency voltage was applied to an internal electrode type plasma source in a carbon dioxide atmosphere at an atmospheric pressure of 0.2 Torr, and a discharge power density (E value) of 520 W · min / m ² , polyimide film NO. Both sides of 1 (thickness 38 μm) were plasma treated.
This film was cut into 20 cm, and 10 sheets were stacked, and a 3 mm thick cushion plate made of glass Teflon (registered trademark) was placed on the top and bottom, and 30 vacuum conditions were applied at 280 ° C. and 130 kg / cm ^2. The pressure was released after cooling to 100 ° C. and the laminate was taken out.
The obtained laminated body was a plate-like body having a thickness of 380 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test. The laminate was sufficiently resistant to external processing such as router processing and drilling.

<Example 7>
A high frequency voltage was applied to an internal electrode type plasma source in a carbon dioxide atmosphere at an atmospheric pressure of 0.2 Torr, and a discharge power density (E value) of 520 W · min / m ² , polyimide film NO. Both sides of 1 (thickness 38 μm) were plasma treated.
The film was cut into 20 cm and then 100 sheets were stacked, and a 3 mm-thick cushion plate made of glass Teflon (registered trademark) was placed on the top and bottom, and 30 vacuum conditions were set at 280 ° C. and 130 kg / cm ^2. The pressure was released after cooling to 100 ° C. and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 3800 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test. The laminate was sufficiently resistant to external processing such as router processing and drilling.

<Example 8>
A high frequency voltage from an internal electrode type plasma source was applied in a carbon dioxide atmosphere at an atmospheric pressure of 0.2 Torr, and a discharge power density (E value) of 520 W · min / m ² , polyimide film NO. 3 (thickness 5 μm) was plasma treated.
This film was cut into 20 cm, and 10 sheets were stacked, and a 3 mm thick cushion plate made of glass Teflon (registered trademark) was placed on the top and bottom, and 30 vacuum conditions were applied at 280 ° C. and 130 kg / cm ^2. The pressure was released after cooling to 100 ° C. and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 50 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test. The laminate was sufficiently resistant to external processing such as router processing and drilling.

<Example 9> Difference in press conditions of Example 3 (temperature 350 ° C.)
A high frequency voltage was applied to an internal electrode type plasma source in a carbon dioxide atmosphere at an atmospheric pressure of 0.2 Torr, and a discharge power density (E value) of 520 W · min / m ² , polyimide film NO. Both sides of 1 (thickness 38 μm) were plasma treated.
The film superposing two later cut into 20 cm, at a Zylon felt cushion thickness 3mm vertically, 350 ° C. using a vacuum press apparatus, and 30 minutes pressed under the conditions of 130 kg / cm ^2, to 100 ° C. After cooling, the pressure was released and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 76 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test. The laminate was sufficiently resistant to external processing such as router processing and drilling.

<Example 10> The press condition difference of Example 3 (temperature 200 degreeC)
A high frequency voltage was applied to an internal electrode type plasma source in a carbon dioxide atmosphere at an atmospheric pressure of 0.2 Torr, and a discharge power density (E value) of 520 W · min / m ² , polyimide film NO. Both sides of 1 (thickness 38 μm) were plasma treated.
Two pieces of this film were cut into 20 cm layers, and a 3 mm thick cushion plate made of glass Teflon (registered trademark) was placed on the top and bottom, and a vacuum press apparatus was used at 200 ° C. and 130 kg / cm ^2. The pressure was released after cooling to 100 ° C. and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 76 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test. The laminate was sufficiently resistant to external processing such as router processing and drilling.

<Example 11> Difference in press conditions of Example 3 (pressure 50 kg / cm2)
A high frequency voltage was applied to an internal electrode type plasma source in a carbon dioxide atmosphere at an atmospheric pressure of 0.2 Torr, and a discharge power density (E value) of 520 W · min / m ² , polyimide film NO. Both sides of 1 (thickness 38 μm) were plasma treated.
Two pieces of this film were cut into 20 cm layers, placed on top and bottom, and 3 mm thick cushion plates made of glass Teflon (registered trademark) were placed on top and bottom, using a vacuum press apparatus at 280 ° C. and 50 kg / cm ^2. The pressure was released after cooling to 100 ° C. and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 76 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test. The laminate was sufficiently resistant to external processing such as router processing and drilling.

<Comparative Example 1>
Polyimide film without plasma treatment NO. After cutting 1 (thickness 38μ) m into 20cm, two sheets were stacked, and a 3mm thick cushion plate made of glass Teflon (registered trademark) was placed on the top and bottom, using a vacuum press device at 280 ° C, 130kg / cm ^{It was} pressed for 30 minutes under the conditions of ² , and after cooling to 100 ° C., the pressure was released and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 76 μm. Table 2 shows the element ratios of the films used for lamination, and Table 3 shows the surface roughness of the release surface of the laminate, the element ratio of the release surface, and the results of the moisture absorption reflow test. Attempts were made to measure CTE and peel strength, but the laminate was easily delaminated during sampling, making measurement impossible.

<Comparative example 2>
A high frequency voltage was applied to an internal electrode type plasma source under an atmospheric pressure of 0.2 Torr and a carbon dioxide atmosphere, and a discharge power density (E value) of 2220 W · min / m ² was applied. Both sides of 1 (thickness 38 μm) were plasma treated.
Two pieces of this film were cut into 20 cm layers, placed on top and bottom, and 3 mm thick cushion plates made of glass Teflon (registered trademark) were placed on top and bottom, using a vacuum press apparatus at 280 ° C. and 130 kg / cm ^2. The pressure was released after cooling to 100 ° C. and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 76 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test. The laminated body was easily peeled off by an external force although it had slight adhesiveness.

<Comparative Example 3>
A high frequency voltage was applied to an internal electrode type plasma source in a carbon dioxide atmosphere at an atmospheric pressure of 0.2 Torr, and a discharge power density (E value) of 520 W · min / m ² , polyimide film NO. Two surfaces (thickness 38 μm) were plasma treated.
Two pieces of this film were cut into 20 cm layers, placed on top and bottom, and 3 mm thick cushion plates made of glass Teflon (registered trademark) were placed on top and bottom, using a vacuum press apparatus at 280 ° C. and 130 kg / cm ^2. The pressure was released after cooling to 100 ° C. and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 76 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test.

<Comparative example 4> (Processing temperature 100 degreeC)
A high frequency voltage was applied to an internal electrode type plasma source in a carbon dioxide atmosphere at an atmospheric pressure of 0.2 Torr, and a discharge power density (E value) of 520 W · min / m ² , polyimide film NO. Both sides of 1 (thickness 38 μm) were plasma treated.
Two pieces of this film were cut into 20 cm layers, placed on top and bottom, and 3 mm thick cushion plates made of glass Teflon (registered trademark) were placed on top and bottom, using a vacuum press machine at 100 ° C. and 130 kg / cm ^2. After the minute pressing, the pressure was released and the laminate was taken out.
The obtained laminate was a plate-like body having a thickness of 76 μm. Table 2 shows the CTE characteristics of the laminate and the element ratio of the film used for lamination, and Table 3 shows the 180 ° peel strength and peel surface roughness of the laminate, the element ratio of the peel surface, and the results of the moisture absorption reflow test.

  A feature of the production method of the present invention is that a surface of a polyimide film obtained by a reaction between an aromatic tetracarboxylic acid and an aromatic diamine having a benzoxazole skeleton is subjected to a plasma treatment, whereby a predetermined surface element ratio (O / (C ratio and A / C ratio) are modified so that the polyimide film that has been surface-modified is heated and pressurized to produce a laminate. The laminate thus produced had an excellent low expansion performance with a thickness of 10 μm or more and a linear expansion coefficient in the plane direction of −5 ppm / ° C. to +7 ppm / ° C. Furthermore, the strength of delamination of the laminate had a practically sufficient strength after the initial stage, after the PCT test, and after the heat standing test. Furthermore, even after severe moisture absorption treatment of JEDEC LEVEL 1, it had good solder reflow performance.

  A laminate laminated without an adhesive layer by the laminate production method of the present invention maintains a good balance between heat resistance with little expansion and contraction at high temperature and strength to withstand weight and the like. It is a laminate that can be effectively used as a mechanical jig or component at high temperature and in a device laminate, and has excellent insulation, heat resistance, and dimensional stability, and can solve mechanical problems in handling. Since the laminate manufacturing method of the present invention can produce a thick plate without using an adhesive, it can be used effectively for device laminates such as sensors and circuits, and has insulation, heat resistance, and dimensional stability. It is excellent in mechanical properties and can solve mechanical problems in handling. In addition, by not using an adhesive, it is possible to provide a substrate that can withstand high-temperature use and can be used effectively for sensors, probes, integrated circuits, and composite devices thereof. large.

Claims (1)

A laminate in which at least two polyimide films obtained by a reaction between an aromatic tetracarboxylic acid and an aromatic diamine having a benzoxazole skeleton are laminated without an adhesive layer, and a discharge power density of 5 to 5 is obtained. The polyimide film, which has been plasma-treated within a range of 2000 W · min / m ² , is manufactured by heating and pressing at least two sheets at a temperature of 150 ° C. or higher and a pressure of 20 kg / cm ² or higher. Is 10 μm or more, the linear expansion coefficient in the plane direction is −5 ppm / ° C. to +7 ppm / ° C., and the linear expansion coefficient in the thickness direction is 5 times or more of the absolute value of the linear expansion coefficient in the plane direction. A laminate of polyimide films, characterized in that