JP5804830B2 - Method for producing metal-clad laminate - Google Patents

Description

  The present invention relates to a method for producing a metal-clad laminate suitably used for a flexible printed wiring board and the like. More specifically, the present invention relates to a method for producing a metal-clad laminate comprising at least a conductor and a plurality of polyimide layers.

  The performance, functionality, and miniaturization of electronic devices are rapidly progressing, and accordingly, there is an increasing demand for miniaturization and weight reduction of electronic components used in electronic devices. In response to the above requirements, semiconductor device packaging methods and wiring boards on which they are mounted are required to have higher density, higher functionality, and higher performance.

  In recent years, FPCs in which a metal layer is directly provided on an insulating film and FPCs in which thermoplastic polyimide is used for an adhesive layer have been proposed. Such an FPC is also called a two-layer FPC because a metal layer is directly formed on an insulating substrate. This two-layer FPC has superior characteristics to a three-layer FPC that uses an epoxy resin-based or acrylic resin-based thermosetting adhesive as the adhesive layer, and can fully meet the requirements for the various characteristics described above. Therefore, demand is expected to grow in the future.

  The two-layer FPC is manufactured using a metal-clad laminate having a structure in which a metal foil is laminated on a substrate. The metal-clad laminate can be produced by casting a polyamic acid, which is a polyimide precursor, on a conductor, casting it, then imidizing it, and metalizing a metal layer directly on the polyimide film by sputtering or plating. And a laminating method in which a polyimide film and a metal foil are bonded via a thermoplastic polyimide.

  Of these, the casting method is the most productive, and is therefore the most cost effective method for producing metal-clad laminates. In the casting method, in order to provide both adhesiveness and dimensional stability, it is generally performed to provide a plurality of polyimide resin layers on a conductor. As a method of producing a plurality of polyimide resin layers on a conductor, one polyimide precursor solution is cast on a conductor and dried, and then the next polyimide precursor solution is cast thereon (for example, a sequential casting method (for example, Patent Document 1) and a co-extrusion method (for example, see Patent Document 2) in which a plurality of polyimide precursor solutions are simultaneously cast on a conductor using a co-extrusion die are known. Among these, the co-extrusion method is more advantageous than the sequential casting method because it is superior in productivity and because there are fewer steps of defects such as contamination due to fewer steps.

  On the other hand, a drawback in using a polyimide material is a high water absorption rate based on the properties of polyimide. This is a problem that also applies to the two-layer FPC. When the water absorption rate of the FPC is high, it may adversely affect the mounting of components using solder. Specifically, moisture taken into the material from the atmosphere is suddenly released out of the system by heating at the time of component mounting, resulting in swelling and whitening of the FPC, and between the materials in the FPC There may be problems with adhesion and electrical properties. In order to avoid such problems related to heat resistance of the hygroscopic solder, for example, it is possible to take measures to remove moisture by predrying the FPC before the mounting process. However, since the number of processes increases, there is a problem in terms of productivity.

  In order to solve the above problems, an adhesive film in which the properties of thermoplastic polyimide used for the adhesive layer are controlled has been proposed. Specifically, by increasing the glass transition temperature of the thermoplastic polyimide contained in the adhesive layer provided on one side or both sides of the heat-resistant base film, improving the heat resistance of the adhesive layer and lowering the water absorption rate, The amount of moisture taken into the film is reduced (see, for example, Patent Document 3 or Patent Document 4). Moreover, when bonding an adhesive film and metal foil, the countermeasure in the process surface of removing a water | moisture content by pre-drying an adhesive film is also proposed (for example, refer patent document 5).

  By these methods, moisture-absorbing solder heat resistance, which has been a drawback when using a polyimide material, is improved. However, with the recent increase in awareness of the environment, there are an increasing number of cases where lead-free solder is used in semiconductor mounting. Since lead-free solder has a melting point of about 40 ° C. higher than eutectic solder currently used, the temperature applied to the material used in the mounting process inevitably rises. For this reason, the current situation is that the moisture-absorbing solder heat resistance required for the material is stricter than before. In addition, when used as a multilayer FPC application, moisture tends to be trapped inside the material due to multilayering, and therefore, defects tend to occur at a lower solder temperature than in the case of a single layer FPC. The materials used in the above are required to have stricter moisture-absorbing solder heat resistance.

Japanese Patent Laid-Open No. 10-323935 Japanese Patent Publication No. 4-79713 JP 2000-129228 A JP 2001-260272 A JP 2001-270037 A

  The present invention has been made in view of the above problems, and its object is to provide a metal-clad laminate having excellent moisture-absorbing solder heat resistance by controlling the properties of thermoplastic polyimide used as an adhesive. There is to do.

  In general, it is known that the imidization temperature of the thermoplastic polyimide is effective as high as possible from the viewpoint of leaving no solvent component in the film after imidization and baking. However, there are polyimides that cannot obtain sufficient moisture-absorbing solder heat resistance when imidized at high temperatures.

  As a result of intensive studies in view of the above-mentioned problems, the present inventor uses a specific monomer in a specific molar ratio for the thermoplastic polyimide composition used in the adhesive layer, and imidizes in a specific temperature range to thereby form an adhesive film. And it discovered that the moisture absorption solder heat resistance of the flexible metal-clad laminate obtained by using it could be improved, and came to complete this invention.

That is, the present invention is a method for producing a metal-clad laminate having at least two or more types of polyimide layers on a conductor, wherein at least the two or more types of polyimide layers in contact with the conductor are thermoplastic. It is a polyimide layer, and the thermoplastic polyimide satisfies the following (A) and (B), and two or more solutions containing a polyimide resin precursor are cast on a conductor by coextrusion to form two or more layers. Including a step of forming a plurality of layers, wherein at least one of the solutions used in the coextrusion contains a chemical dehydrating agent and a catalyst, and imidizes the polyimide precursor at a temperature of 310 to 410 ° C. This is a method for producing a metal-clad laminate.
(A) The thermoplastic polyimide is mainly composed of pyromellitic dianhydride and 2,2-bis- [4- (4-aminophenoxy) phenyl] propane, and other than pyromellitic dianhydride Diamine other than 2,2-bis- [4- (4-aminophenoxy) phenyl] propane and / or a diamine other than 2,2-bis- [4- (4-aminophenoxy) phenyl] propane In 100 mol% of the diamine component, 5 to 30 mol%,
(B) The total number of moles of acid dianhydride other than pyromellitic dianhydride and diamine other than 2,2-bis- [4- (4-aminophenoxy) phenyl] propane is 100 moles of acid dianhydride component. % And 100 mol% of the diamine component in a total of 200 mol% is 5 to 50 mol%.

  It is preferable that a polyimide layer other than the thermoplastic polyimide layer includes at least a heat-resistant polyimide layer.

  The polyimide layer is preferably formed by providing a thermoplastic polyimide layer on both sides of the heat-resistant polyimide layer.

  On the conductor, a thermoplastic polyimide precursor solution-a heat-resistant polyimide precursor solution-a thermoplastic polyimide precursor solution is cast on the conductor by coextrusion in the order described above, and then dried and fired to obtain a conductor-thermoplastic polyimide layer. -After preparing the laminated body which consists of-heat resistant polyimide layer-thermoplastic polyimide layer, it is preferable to thermally laminate the thermoplastic polyimide layer and the 2nd conductor which are not in contact with the conductor of the said laminated body.

  The acid dianhydride other than pyromellitic dianhydride contained in the thermoplastic polyimide is preferably 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride.

  The diamine other than 2,2-bis- [4- (4-aminophenoxy) phenyl] propane contained in the thermoplastic polyimide is preferably 4,4'-oxydianiline.

  The metal foil peeling strength is preferably 10 N / cm or more when peeled in the 180 ° direction.

The thermoplastic polyimide preferably has a storage elastic modulus of 1 × 10 ⁸ Pa or more at 280 ° C. and a storage elastic modulus of less than 1 × 10 ⁸ Pa at 350 ° C.

  It is preferable that the heat-resistant polyimide film contains a thermoplastic polyimide block component in an amount of 20 to 60 mol% of the whole polyimide.

  The repeating unit n of the block component of the thermoplastic polyimide is preferably 3 to 99.

  The metal-clad laminate obtained by the present invention is excellent in moisture absorption solder heat resistance while maintaining excellent adhesion.

  Hereinafter, preferred embodiments of the metal-clad laminate according to the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

  The present invention is a method for producing a metal-clad laminate having at least two or more polyimide layers on a conductor and needs to be a coextrusion method. The coextrusion method according to the present invention is a film production method including a step of casting two or more solutions containing a polyimide resin precursor on a conductor by coextrusion to form two or more layers. is there. The two or more layers are simultaneously supplied with two or more solutions containing a polyimide resin precursor to an extruder having two or more multilayer dies, and at least two layers of the solution are discharged from the outlet of the multilayer die. It is obtained by extruding as a thin film. To describe a commonly used method, both the solutions extruded from two or more multilayer dies are continuously extruded onto a conductor held in a backup roll, and then a multilayer thin film on the support. The desired metal-clad laminate is obtained by volatilizing at least a portion of the solvent of the solid body and sufficiently heat-treating it at a high temperature to substantially remove the solvent and advance imidization. Further, for the purpose of improving the melt fluidity of the adhesive layer, the imidization rate may be intentionally lowered and / or the solvent may be left.

  As the above-mentioned multilayer die having two or more layers, those having various structures can be used. For example, a T-die for producing a multi-layer film can be used. In addition, any conventionally known structure can be suitably used, and feed block T dies and multi-manifold T dies are exemplified as particularly suitable ones.

  The conductor according to the present invention is not particularly limited as long as it is a metal foil, but is preferably a copper foil, particularly a copper foil having a thickness of 5 to 20 μm, or an ultrathin copper foil with a carrier copper foil. As the copper foil, either a rolled copper foil or an electrolytic copper foil can be suitably used, and any known treatment can be used for the surface treatment of the copper foil.

  In the two or more types of polyimide layers formed on the conductor, the layer in contact with the conductor needs to be a thermoplastic polyimide. More preferably, in order to impart dimensional stability, it is preferable that the polyimide layer other than the thermoplastic polyimide layer includes at least a heat-resistant polyimide layer.

  In general, polyimide is obtained by a dehydration conversion reaction from a polyimide precursor, that is, a polyamic acid. As a method for performing the conversion reaction, a thermal curing method performed only by heat and a chemical curing method using a chemical curing agent are used. The two methods are most widely known. However, in the present invention, it is essential to employ a chemical curing method, and at least one solution used for the coextrusion contains a chemical dehydrating agent and a catalyst.

  Here, the chemical curing agent includes a chemical dehydrating agent and a catalyst. The chemical dehydrating agent here is a dehydrating ring-closing agent for polyamic acid, and as its main component, aliphatic acid anhydride, aromatic acid anhydride, N, N'-dialkylcarbodiimide, lower aliphatic halide, halogen A lower aliphatic acid anhydride, an arylsulfonic acid dihalide, a thionyl halide, or a mixture of two or more thereof can be preferably used. Of these, aliphatic acid anhydrides and aromatic acid anhydrides work particularly well. A suitable introduction amount of the chemical dehydrating agent is 0.5 to 4.0 mol, preferably 0.7 to 4.0, relative to 1 mol of the amic acid unit in the polyamic acid contained in the solution containing the chemical dehydrating agent. Mol, particularly preferably 1.0 to 4.0 mol. If the above range is exceeded, the conductor may corrode. On the other hand, below the above range, the curing rate is not sufficient and the effects of the present invention may not be exhibited.

  The catalyst is a component having an effect of promoting the dehydration ring-closing action of the curing agent on the polyamic acid. For example, an aliphatic tertiary amine, an aromatic tertiary amine, or a heterocyclic tertiary amine can be used. . Of these, nitrogen-containing heterocyclic compounds such as imidazole, benzimidazole, isoquinoline, quinoline, or β-picoline are preferred. Furthermore, introduction of an organic polar solvent into a solution composed of a chemical dehydrating agent and a catalyst can be appropriately selected. A suitable introduction amount of the catalyst is 0.05 to 2.0 mol, preferably 0.1 to 2.0 mol, particularly preferably 0.1 mol to 1 mol of amic acid unit in the polyamic acid contained in the solution containing the catalyst. Is 0.2 to 2.0 mol. When the above range is exceeded, the catalyst may remain in the polyimide layer and may be inferior in long-term heat resistance. On the other hand, below the above range, the curing rate is not sufficient and the effects of the present invention may not be exhibited.

  The polyimide precursor for introducing the chemical curing agent can suitably exhibit the effect of the present invention regardless of the layer constituting the layer, but the method of introducing the chemical curing agent only to the heat-resistant polyimide layer is an apparatus. The most favorable results can be obtained with regard to simplification of the conductor, prevention of corrosion of the conductor, and physical properties of the polyimide layer.

  There is no particular limitation regarding the method of volatilization of the solvent in the precursor solution of the heat-resistant polyimide extruded from the multilayer die of two or more layers and the solution containing the thermoplastic polyimide or the precursor of the thermoplastic polyimide, The method by heating and / or blowing is the simplest method. If the temperature at the time of heating is too high, the solvent is volatilized rapidly, and the trace of the volatilization becomes a factor for forming minute defects in the finally obtained multilayer film. Preferably there is.

  As for the imidization time, it is sufficient to take a time sufficient for the imidization and drying to be substantially completed, and it is not limited uniquely, but generally it is appropriately in the range of about 1 to 600 seconds. Is set. At this time, it is necessary to finally heat at a temperature of 310 to 410 ° C. Moreover, it is preferable to heat in the range of 320-400 degreeC. Moreover, it is more preferable to heat in the range of 330-390 degreeC. If the temperature is higher than this temperature, the thermoplastic polyimide may be thermally deteriorated to cause a problem. Conversely, if the temperature is lower than this temperature, the predetermined effect may not be exhibited. For example, heating at 300 ° C. or lower causes problems such as deterioration in heat resistance of moisture-absorbing solder and reduction in adhesion strength with the copper foil after moisture absorption. When heated at 420 ° C. or higher, there arises a problem that the adhesion strength with the copper foil is lowered.

  Moreover, it can also be preferably selected to provide a conductor on both sides of the polyimide layer by thermally laminating the second conductor with the thermoplastic polyimide layer on the side not in contact with the conductor of the obtained metal-clad laminate. The second conductor according to the present invention is not limited as long as it is a metal foil like the conductor, but is a copper foil, particularly a copper foil with a thickness of 5 to 20 μm, or an ultrathin copper foil with a carrier copper foil. It is preferable. As the copper foil, either a rolled copper foil or an electrolytic copper foil can be suitably used, and any known treatment can be used for the surface treatment of the copper foil.

  The method of thermal lamination is not particularly limited, and examples thereof include a double belt method and a hot roll method in which pressure is applied with a pair of hot rolls. Also in the hot roll method, a method of sandwiching a protective film between the hot roll and the metal-clad laminate, a method of surrounding the hot roll with a booth, and filling the inside of the booth with an inert gas can be mentioned.

  When producing a double-sided metal-clad laminate, it is preferable that both sides of the outermost layer of the polyimide layer are thermoplastic polyimide, and the two or more types of polyimide layers are provided with a thermoplastic polyimide layer on both sides of the heat-resistant polyimide layer. It is preferable to become.

  On the conductor, a precursor solution of thermoplastic polyimide-a precursor solution of a heat-resistant polyimide-a precursor solution of a thermoplastic polyimide is cast on the conductor by coextrusion in the above order, and then dried and fired. After producing a laminate composed of a plastic polyimide layer-a heat-resistant polyimide layer-a thermoplastic polyimide layer, both sides of the laminate are thermally laminated with a thermoplastic polyimide layer that is not in contact with a conductor of the laminate and a second conductor. It is preferable to obtain a metal-clad laminate.

<Thermoplastic polyimide>
The thermoplastic polyimide according to the present invention has a glass transition temperature and is 10 to 400 ° C. (temperature increase rate: 10 ° C./temperature) in a compression mode (probe diameter 3 mmφ, load 5 g) in a thermomechanical analyzer (TMA). Min) which causes permanent compression deformation in the temperature range. In view of the fact that lamination with an existing apparatus is possible and the heat resistance of the resulting metal-clad laminate is not impaired, the thermoplastic polyimide according to the present invention has a glass transition temperature in the range of 150 to 310 ° C. (Hereinafter also referred to as “Tg”). Tg can be obtained from the value of the inflection point of the storage elastic modulus measured by a dynamic viscoelasticity measuring device (DMA).

The thermoplastic polyimide according to the present invention must satisfy the following (A) and (B) in order to improve solder heat resistance.
(A) The thermoplastic polyimide is mainly composed of pyromellitic dianhydride and 2,2-bis- [4- (4-aminophenoxy) phenyl] propane, and other than pyromellitic dianhydride Diamine other than 2,2-bis- [4- (4-aminophenoxy) phenyl] propane and / or a diamine other than 2,2-bis- [4- (4-aminophenoxy) phenyl] propane In 100 mol% of the diamine component, 5 to 30 mol%,
(B) The total number of moles of acid dianhydride other than pyromellitic dianhydride and diamine other than 2,2-bis- [4- (4-aminophenoxy) phenyl] propane is 100 moles of acid dianhydride component. % And 100 mol% of the diamine component in a total of 200 mol% is 5 to 50 mol%.

  In the present specification, the main component means 50% or more.

  When the above (A) and (B) are not satisfied, the predetermined effect of the thermoplastic polyimide may not be exhibited. For example, when an acid dianhydride other than pyromellitic dianhydride is contained in an amount of less than 10 mol% in 100 mol% of the tetracarboxylic dianhydride component, a problem such as a decrease in adhesion strength with the copper foil may occur. On the other hand, when an acid dianhydride other than pyromellitic dianhydride is contained in an amount of more than 50 mol% in 100 mol% of the tetracarboxylic dianhydride component, a problem such as deterioration of heat resistance of the hygroscopic solder may occur. When a diamine other than 2,2-bis- [4- (4-aminophenoxy) phenyl] propane is contained in less than 5 mol% in 100 mol% of the diamine component, a problem such as a decrease in adhesion strength with copper foil may occur. is there. On the contrary, when diamine other than 2,2-bis- [4- (4-aminophenoxy) phenyl] propane is contained in an amount of more than 50 mol% in 100 mol% of the diamine component, there arises a problem that the heat resistance of the hygroscopic solder is deteriorated. There is a case.

  The tetracarboxylic dianhydride component may contain a component other than the main component, the diamine component may contain a component other than the main component, and both the tetracarboxylic dianhydride component and the diamine component are the main components. Other components may be included.

  The acid dianhydride other than pyromellitic dianhydride is 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, so that it has good moisture-absorbing solder heat resistance and good adhesion to copper foil. It is preferable for obtaining strength. The diamine other than 2,2-bis- [4- (4-aminophenoxy) phenyl] propane is 4,4′-oxydianiline, so that good moisture-absorbing solder heat resistance and good adhesion to copper foil It is preferable for obtaining strength.

Furthermore, it is preferable that the storage elastic modulus at 280 ° C. of the thermoplastic polyimide according to the present invention is 1 × 10 ⁸ Pa or more in order to exhibit good moisture-absorbing solder heat resistance. When the storage modulus of thermoplastic polyimide at the solder test temperature is low, the moisture in the multilayer polyimide is suddenly released outside the system through the adhesive layer, resulting in whitening or the like in the multilayer polyimide or flexible metal-clad laminate. Can cause blistering. Further, at the temperature at which the multi-layer polyimide and the metal foil are bonded when the flexible metal-clad laminate is manufactured, the thermoplastic polyimide needs to be sufficiently softened in order to exhibit adhesiveness. The plastic polyimide preferably has a storage elastic modulus at 350 ° C. of less than 1 × 10 ⁸ Pa. Furthermore, it is preferable that the thermoplastic polyimide has a storage elastic modulus at 300 ° C. of 1 × 10 ⁷ Pa or more and a storage elastic modulus at 340 ° C. of less than 1 × 10 ⁸ Pa, and is further contained in the adhesive layer. The thermoplastic polyimide preferably has a storage elastic modulus at 300 ° C. of 3 × 10 ⁷ Pa or more and a storage elastic modulus at 340 ° C. of less than 8 × 10 ⁷ Pa. Moreover, when the storage elastic modulus is large at the temperature to be bonded to the metal foil, the copper foil adhesion strength is lowered, and problems such as peeling of the copper foil occur when the obtained copper clad laminate is processed. In addition, the low storage elastic modulus at the temperature to be bonded to the metal foil is a necessary condition for the good adhesion strength of the copper foil, and even if the storage elastic modulus is small, the adhesion strength is due to poor matching with the copper foil. May be low.

  In addition, a filler can be added for the purpose of improving various film properties such as slidability, thermal conductivity, conductivity, corona resistance, and loop stiffness. Any filler may be used, but preferred examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica and the like.

The particle size of the filler is not particularly limited because it is determined by the film characteristics to be modified and the kind of filler to be added, but generally the average particle size is 0.05 to 100 μm, preferably 0.1. It is -75 micrometers, More preferably, it is 0.1-50 micrometers, Most preferably, it is 0.1-25 micrometers. If the particle size is below this range, the modification effect is less likely to appear. If the particle size is above this range, the surface properties may be greatly impaired or the mechanical properties may be greatly deteriorated. Further, the number of added parts of the filler is not particularly limited because it is determined by the film properties to be modified, the filler particle diameter, and the like. Generally, the addition amount of the filler is 0.01 to 100 parts by weight, preferably 0.01 to 90 parts by weight, and more preferably 0.02 to 80 parts by weight with respect to 100 parts by weight of the polyimide. If the amount of filler added is less than this range, the effect of modification by the filler hardly appears, and if it exceeds this range, the mechanical properties of the film may be greatly impaired. Addition of filler
1. 1. A method of adding to a polymerization reaction solution before or during polymerization 2. A method of kneading fillers using three rolls after the completion of polymerization. Any method such as preparing a dispersion containing filler and mixing it with a polyamic acid organic solvent solution may be used, but a method of mixing a dispersion containing filler with a polyamic acid solution, particularly immediately before film formation. This method is preferable because the contamination by the filler in the production line is minimized. When preparing a dispersion containing a filler, it is preferable to use the same solvent as the polymerization solvent for the polyamic acid. Further, in order to disperse the filler satisfactorily and stabilize the dispersion state, a dispersant, a thickener and the like can be used within a range not affecting the film physical properties.

  The thickness of the thermoplastic polyimide layer in the multilayer polyimide according to the present invention is not limited, but may be appropriately selected in consideration of the thickness of the entire multilayer polyimide, the surface roughness of the metal foil to be bonded, The range of 1-12 micrometers is preferable, Furthermore, the range of 1.3-10 micrometers is preferable, Furthermore, the range of 1.5-8 micrometers is more preferable. Even if the adhesive layer is made thicker than the above range, the adhesive strength does not improve proportionally, and conversely, it may be difficult to control the linear expansion coefficient of the multilayer polyimide. If the adhesive layer is thinner than the above range, the adhesive layer may not sufficiently bite into the irregularities on the surface of the metal foil, resulting in poor adhesion.

  Moreover, the thermoplastic polyimide of this invention can control various characteristics by limiting the raw material ratio to be used.

<Metal-clad laminate>
The metal-clad laminate according to the present invention is moisture-absorbing solder heat resistant (for example, after absorbing moisture for 24 hours under a humidified condition of 85 ° C. and 85% RH, and then dipping in a solder bath at 300 ° C. for 10 seconds. , A level at which appearance abnormality such as swelling and whitening does not occur) can be improved.

  The metal-clad laminate of the present invention preferably has a metal foil peeling strength of 10 N / cm or more when peeled in the 180 ° direction. When the metal foil peeling strength is less than 10 N / cm, problems such as peeling of the copper foil occur when the obtained copper-clad laminate is processed.

<Heat resistant polyimide>
Here, the heat-resistant polyimide film in the present invention refers to a film that melts and maintains the shape of the film when the high molecular weight film is heated to about 350 ° C to 500 ° C. As a more specific method for determining a heat-resistant polyimide film, a polyamic acid solution is prepared by adding a molar ratio of a diamine to be used and an acid dianhydride to an appropriate solvent so that the molar ratio is virtually 100: 97 to 97: 100. Then, the polyamic acid solution is applied onto a smooth support so that the final thickness is 10 to 30 μm and the length of one side is 25 cm or more. Specific examples of the smooth support include PET film, aluminum foil, and copper foil. Examples of the method for applying the final thickness to 10 to 30 μm include a bar coater, a comma coater, and a doctor blade. Furthermore, the coating film of the polyamic acid solution coated on the support is dried until it is self-supporting, peeled off from the support, fixed to a metal frame, and imidization and drying are substantially terminated. To produce a single layer sheet of polyimide. Examples of the drying and imidization methods include hot air and far infrared rays, and the temperature conditions are appropriately selected depending on the solvent species and the molecular structure of the polyamic acid. The polyimide single-layer sheet thus obtained was fixed to a square metal frame having an inner side of 20 cm each so that the center of the polyimide single-layer sheet and the metal frame substantially coincided, and 350 ° C. to 500 ° C. In the atmosphere of 5 minutes or more so that the film is substantially horizontal. At that time, if the thermal deformation at the center of the film is less than 1 cm in the vertically downward direction, the film made of the polyimide is determined to be heat resistant.

  The heat-resistant polyimide film according to the present invention is produced using polyamic acid as a precursor. Any known method can be used as a method for producing the polyamic acid. Usually, the polyamic acid obtained by dissolving a substantially equimolar amount of an aromatic dianhydride and an aromatic diamine in an organic solvent is obtained. The organic solvent solution is produced by stirring under controlled temperature conditions until the polymerization of the acid dianhydride and the diamine is completed. These polyamic acid solutions are usually obtained at a concentration of 5 to 35% by weight, preferably 10 to 30% by weight. When the concentration is in this range, an appropriate molecular weight and solution viscosity are obtained.

As the polymerization method, any known method and a combination thereof can be used. The characteristic of the polymerization method in the polymerization of polyamic acid is the order of addition of the monomers, and the physical properties of the polyimide obtained can be controlled by controlling the order of addition of the monomers. Therefore, in the present invention, any method of adding monomers may be used for the polymerization of polyamic acid. The following method is mentioned as a typical polymerization method. That is,
1) A method in which an aromatic diamine is dissolved in an organic polar solvent, and this is reacted with a substantially equimolar aromatic tetracarboxylic dianhydride for polymerization.
2) An aromatic tetracarboxylic dianhydride is reacted with a small molar amount of an aromatic diamine compound in an organic polar solvent to obtain a prepolymer having acid anhydride groups at both ends. Subsequently, a method of polymerizing with an aromatic diamine compound so that the aromatic tetracarboxylic dianhydride and the aromatic diamine compound are substantially equimolar in all steps,
3) An aromatic tetracarboxylic dianhydride and an excess molar amount of the aromatic diamine compound are reacted in an organic polar solvent to obtain a prepolymer having amino groups at both ends. Subsequently, after adding an aromatic diamine compound here, using the aromatic tetracarboxylic dianhydride so that the aromatic tetracarboxylic dianhydride and the aromatic diamine compound are substantially equimolar in all steps. How to polymerize,
4) A method in which an aromatic tetracarboxylic dianhydride is dissolved and / or dispersed in an organic polar solvent and then polymerized using an aromatic diamine compound so as to be substantially equimolar,
5) A method of polymerizing by reacting a mixture of substantially equimolar aromatic tetracarboxylic dianhydride and aromatic diamine in an organic polar solvent,
And so on. These methods may be used singly or in combination.

  The heat-resistant polyimide film of the present invention preferably contains 20 to 60 mol% of a thermoplastic polyimide block component in the molecule. By using a heat-resistant film in this range, it becomes possible to improve moisture-absorbing solder heat resistance. The reason for this has not been clarified yet, but is presumed as follows. Defects in the moisture absorption solder heat resistance test, that is, whitening and foaming, are caused by rapid expansion at the interface between the metal foil and the polyimide layer when the moisture absorbed in the polyimide layer is immersed in a heated solder bath. This is a phenomenon that occurs. By introducing the block component of the thermoplastic polyimide layer into the heat-resistant polyimide layer, the water vapor transmission rate is remarkably improved, which prevents the rapid expansion of moisture at the metal foil / polyimide layer interface. Yes. Furthermore, the thermoplastic polyimide block component is contained in an amount of 20 to 60 mol%, preferably 25 to 55 mol%, particularly preferably 30 to 50 mol% of the whole polyimide. If the thermoplastic polyimide block component is below this range, it will be difficult to develop the excellent adhesiveness of the present invention, and if it exceeds this range, it will be difficult to finally form a heat-resistant polyimide film. For the purpose of ideally forming the block component, after forming the block component of the thermoplastic polyimide precursor, the method of forming the non-thermoplastic polyimide precursor using the remaining diamine and / or acid dianhydride is used. preferable. Under the present circumstances, it is preferable to use combining the method of said 1) -5) partially.

  In the present invention, the thermoplastic polyimide block component refers to a component that melts when the high molecular weight film is heated to about 350 ° C. to 500 ° C. and does not retain the shape of the film. As a more specific determination method for the thermoplastic polyimide block component, the molar ratio of the diamine to be used and the acid dianhydride is added to an appropriate solvent so that the molar ratio is virtually 100: 97 to 97: 100. A solution is prepared, and then the polyamic acid solution is coated on a smooth support so that the final thickness is 10 to 30 μm and the length of one side is 25 cm or more. Specific examples of the smooth support include PET film, aluminum foil, and copper foil. Examples of the method for applying the final thickness to 10 to 30 μm include a bar coater, a comma coater, and a doctor blade. Furthermore, the coating film of the polyamic acid solution coated on the support is dried until it is self-supporting, peeled off from the support, fixed to a metal frame, and imidization and drying are substantially terminated. To produce a single layer sheet of polyimide. Examples of the drying and imidization methods include hot air and far infrared rays, and the temperature conditions are appropriately selected depending on the solvent species and the molecular structure of the polyamic acid. The polyimide single-layer sheet thus obtained was fixed to a square metal frame having an inner side of 20 cm each so that the center of the polyimide single-layer sheet and the metal frame substantially coincided, and 350 ° C. to 500 ° C. In the atmosphere of 5 minutes or more so that the film is substantially horizontal. At that time, if the center of the film is thermally deformed by 1 cm or more vertically downward, the block component made of the polyimide is determined to be thermoplastic.

Here, the mol% of the thermoplastic polyimide block component, that is, the content of the thermoplastic polyimide block component in the present invention was synthesized by using the thermoplastic polyimide block component excessively with respect to the acid component. In the case of synthesis by the following calculation formula (1), the acid component is calculated according to the following calculation formula (2) when synthesized in excess with respect to the diamine component.
(Thermoplastic polyimide block component content) = a / b × 100 Formula (1)
a: Amount of diamine contained in thermoplastic polyimide block component (mol)
b: Total diamine amount (mol)
(Thermoplastic polyimide block component content) = a / b × 100 Formula (2)
a: Amount of acid component contained in thermoplastic polyimide block component (mol)
b: Total acid component amount (mol)
Further, the repeating unit n of the thermoplastic polyimide block component is preferably 3 to 99, more preferably 4 to 90. When the repeating unit n is less than this range, excellent adhesiveness is hardly exhibited and the hygroscopic expansion coefficient tends to be large. On the other hand, if the repeating unit n exceeds this range, the storage stability of the polyimide precursor solution tends to deteriorate, and the reproducibility of polymerization tends to decrease, such being undesirable.

  The thermoplastic polyimide block component in the present invention preferably has a glass transition temperature (Tg) in the range of 150 to 300 ° C. in the high molecular weight body. Tg can be obtained from the inflection point value of the storage elastic modulus measured by a dynamic viscoelasticity measuring device (DMA).

The monomer that forms the thermoplastic polyimide block component of the present invention will be described.
Examples that can be preferably used as the diamine main component constituting the thermoplastic polyimide block component of the present invention include 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 3,3. '-Diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 4,4'-oxydianiline, 3,3'-oxydianiline, 3,4'-oxydianiline, 4,4'-diaminodiphenyldiethyl Silane, 4,4′-diaminodiphenylsilane, 4,4′-diaminodiphenylethylphosphine oxide, 4,4′-diaminodiphenyl N-methylamine, 4,4′-diaminodiphenyl N-phenylamine, 1,4- Diaminobenzene (p-phenylenediamine), bis {4- (4-aminophenoxy) Enyl} sulfone, bis {4- (3-aminophenoxy) phenyl} sulfone, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 1,3- Bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 3, Examples include 3′-diaminobenzophenone, 4,4′-diaminobenzophenone, 2,2-bis (4-aminophenoxyphenyl) propane, and these can be used alone or in combination. These examples are examples that are suitably used as the main component, and any diamine can be used as the accessory component. Examples of diamines that can be particularly preferably used among these are 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 1,3-bis (3-amino). Phenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 2,2-bis (4 -Aminophenoxyphenyl) propane.

  Among these, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride is particularly preferable because the adhesiveness can be easily controlled within a suitable range.

  Examples that can be suitably used as the acid component constituting the thermoplastic polyimide block component include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 4,4′-oxydiphthalic dianhydride and the like can be mentioned, and these can be used alone or in combination. In the present invention, at least 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 4,4′-oxydiphthalic acid It is preferable to use at least one acid dianhydride selected from the group consisting of anhydrides as an essential component. By using these acid dianhydrides, high adhesion to the adhesive polyimide layer, which is the effect of the present invention, can be easily obtained.

  In this invention, the suitable example of the diamine and acid dianhydride which are used when making it react with a thermoplastic polyimide block component (at this stage, a thermoplastic polyimide precursor block component) and manufacturing a heat resistant polyimide precursor is given. . Although various characteristics change depending on the combination of diamine and acid dianhydride, it cannot be specified unconditionally, but ultimately, a diamine or an acid that becomes a heat-resistant polyimide is used. As such a diamine, it is preferable to use a rigid component such as paraphenylenediamine and a derivative thereof, benzidine and a derivative thereof as a main component. By using these diamines having a rigid structure, it becomes non-thermoplastic and it is easy to achieve a high elastic modulus. Moreover, it is preferable to use pyromellitic dianhydride as a main component as an acid component. As is well known, pyromellitic dianhydride tends to give heat-resistant polyimide because of its rigid structure.

  In the present invention, from the viewpoint of ease of polymerization control and convenience of the apparatus, after first synthesizing a thermoplastic polyimide precursor block component, diamine and acid dianhydride are further added at an appropriately designed molar fraction to provide heat resistance. It is preferable to use a polymerization method using a polyimide precursor.

  As a preferred solvent for synthesizing a polyimide precursor (hereinafter referred to as polyamic acid), any solvent that dissolves polyamic acid can be used, but amide solvents, that is, N, N-dimethylformamide, N, N -Dimethylacetamide, N-methyl-2-pyrrolidone and the like, and N, N-dimethylformamide and N, N-dimethylacetamide can be particularly preferably used.

  Hereinafter, based on an Example and a comparative example, it demonstrates still more concretely about this invention. In addition, this invention is not limited to the following Example.

[Hygroscopic solder heat resistance of flexible metal-clad laminate]
The double-sided flexible metal-clad laminates obtained in the examples and comparative examples were cut into 3.5 cm squares, and one side (for convenience, the A side) had a 2.5 cm square copper foil layer left in the center of the sample. On the opposite side (for convenience, B side), five samples were prepared by removing the excess copper foil layer by etching treatment so that the copper foil layer remained on the entire surface. The obtained sample was 40 ° C., 90% R.D. H. The sample was left for 96 hours under the humidification conditions, and a moisture absorption treatment was performed. After the moisture absorption treatment, the sample was immersed in a solder bath at 260 ° C., 280 ° C., or 300 ° C. for 10 seconds. For the sample after solder immersion, the copper foil layer on the B side is completely removed by etching, and if the appearance of the part where the copper foil overlaps is not changed, ○ (good), whitening of the multilayer polyimide layer, swelling, copper When any peeling of the foil layer was confirmed, it was set as x (bad).

[Metal foil peel strength of flexible metal-clad laminate]
A sample was prepared according to “6.5 peel strength” of JIS C6471, and a 5 mm wide metal foil part was peeled off at a peeling angle of 180 degrees and 50 mm / min, and the load was measured. Furthermore, as the adhesive strength in a high temperature and high humidity environment, the substrate was left to stand at 121 ° C., humidity 95%, 2 atm oven for 96 hours, allowed to reach room temperature, and then evaluated by 90 ° peel strength. .

[Measurement of storage modulus of polyimide film with adhesive layer only]
The polyimide film obtained from the polyimide precursor resin of each synthesis example was measured using a DMS6100 manufactured by Seiko Electronics Co., Ltd. (sample size width: 9 mm, length: 50 mm) at a frequency of 1, 5, and 10 Hz. Measurements were made at a temperature range of 20 to 400 ° C. at 3 ° C./min, and the storage elastic modulus values at 280 ° C. and 350 ° C. were read.

(Synthesis Example 1; Synthesis of thermoplastic polyimide precursor)
807.2 g of N, N-dimethylformamide (hereinafter also referred to as DMF), 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) in a glass flask having a capacity of 2000 ml 111.0 g was added, and 57.2 g of pyromellitic dianhydride (hereinafter also referred to as PMDA) was added while stirring under a nitrogen atmosphere, followed by stirring at 25 ° C. for 1 hour. A solution in which 1.8 g of PMDA was dissolved in 22.8 g of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to the viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 2: Synthesis of thermoplastic polyimide precursor)
Add 807.3 g of DMF and 110.4 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml and stir in a nitrogen atmosphere. While adding 4.0 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (hereinafter also referred to as BPDA) and stirring under a nitrogen atmosphere, 53.9 g of PMDA was added, and 25 ° C. For 1 hour. A solution prepared by dissolving 1.8 g of PMDA in 22.7 g of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 3; Synthesis of thermoplastic polyimide precursor)
Add 807.5 g of DMF and 109.7 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml and stir in a nitrogen atmosphere. While adding 7.9 g of BPDA while stirring under a nitrogen atmosphere, 50.7 g of PMDA was added and stirred at 25 ° C. for 1 hour. A solution in which 1.7 g of PMDA was dissolved in 22.5 g of DMF was separately prepared, and this was gradually added to the reaction solution while being careful of the viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 4; Synthesis of thermoplastic polyimide precursor)
Add 802.6 g of DMF and 107.9 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml and stir in a nitrogen atmosphere. While adding 8.5 g of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (hereinafter also referred to as BTDA), stirring 7.7 g of BPDA under a nitrogen atmosphere and stirring under a nitrogen atmosphere While adding 47.0 g of PMDA, the mixture was stirred at 25 ° C. for 1 hour. A solution prepared by dissolving 1.8 g of PMDA in 23.3 g of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 5: Synthesis of thermoplastic polyimide precursor)
Add 807.6 g of DMF and 109.0 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml, and stir in a nitrogen atmosphere. While adding 11.7 g of BPDA and stirring under a nitrogen atmosphere, 47.5 g of PMDA was added and stirred at 25 ° C. for 1 hour. A solution in which 1.7 g of PMDA was dissolved in 22.4 g of DMF was separately prepared, and this was gradually added to the reaction solution while being careful of the viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 6; Synthesis of thermoplastic polyimide precursor)
Add 807.7 g of DMF and 108.4 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml and stir in a nitrogen atmosphere. While adding 15.5 g of BPDA and stirring under a nitrogen atmosphere, 44.4 g of PMDA was added and stirred at 25 ° C. for 1 hour. A solution in which 1.7 g of PMDA was dissolved in 22.3 g of DMF was separately prepared, and this was gradually added to the reaction solution while being careful of the viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 7; Synthesis of thermoplastic polyimide precursor)
Add 808.0 g of DMF and 107.1 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml and stir in a nitrogen atmosphere. While adding 23.0 g of BPDA while stirring under a nitrogen atmosphere, 38.1 g of PMDA was added and stirred at 25 ° C. for 1 hour. A solution in which 1.7 g of PMDA was dissolved in 22.0 g of DMF was separately prepared, and this was gradually added to the reaction solution while being careful of the viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 8; Synthesis of thermoplastic polyimide precursor)
Add 808.5 g of DMF and 104.7 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml and stir in a nitrogen atmosphere. While adding 37.5 g of BPDA and stirring under a nitrogen atmosphere, 26.1 g of PMDA was added and stirred at 25 ° C. for 1 hour. A solution in which 1.7 g of PMDA was dissolved in 21.5 g of DMF was separately prepared, and this was gradually added to the reaction solution while being careful of the viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 9: Synthesis of thermoplastic polyimide precursor)
Add 809.0 g of DMF and 102.3 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml and stir in a nitrogen atmosphere. While adding 51.3 g of BPDA and stirring under a nitrogen atmosphere, 16.3 g of PMDA was added and stirred at 25 ° C. for 1 hour. A solution in which 1.6 g of PMDA was dissolved in 21.0 g of DMF was separately prepared, and this was gradually added to the above reaction solution while being careful of the viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 10; Synthesis of thermoplastic polyimide precursor)
Add 806.8 g of DMF and 107.3 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml, and stir in a nitrogen atmosphere. While adding 2.8 g of 4,4′-oxydianiline (hereinafter also referred to as “4,4′-ODA”), stirring under a nitrogen atmosphere, adding 58.2 g of PMDA and stirring at 25 ° C. for 1 hour did. A solution prepared by dissolving 1.8 g of PMDA in 22.7 g of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 11; Synthesis of thermoplastic polyimide precursor)
Add 806.4 g of DMF and 103.4 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask having a capacity of 2000 ml, and stir in a nitrogen atmosphere. While adding 5.6 g of 4,4′-oxydianiline (hereinafter also referred to as “4,4′-ODA”), while stirring under a nitrogen atmosphere, add 59.2 g of PMDA and stir at 25 ° C. for 1 hour. did. A solution prepared by dissolving 1.8 g of PMDA in 23.6 g of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 12; Synthesis of thermoplastic polyimide precursor)
Add 804.7 g of DMF and 86.4 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml, and stir in a nitrogen atmosphere. While adding 18.1 g of 4,4′-oxydianiline (hereinafter also referred to as “4,4′-ODA”) and stirring under a nitrogen atmosphere, 63.6 g of PMDA was added and the mixture was heated at 25 ° C. for 1 hour. Stir. A solution in which 2.0 g of PMDA was dissolved in 25.4 g of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to the viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 13; Synthesis of thermoplastic polyimide precursor)
Add 802.6 g of DMF and 66.7 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml, and stir in a nitrogen atmosphere. While adding 32.5 g of 4,4′-oxydianiline (hereinafter also referred to as “4,4′-ODA”), stirring under a nitrogen atmosphere, adding 68.7 g of PMDA and stirring at 25 ° C. for 1 hour did. A solution in which 2.0 g of PMDA was dissolved in 25.4 g of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to the viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 14; Synthesis of thermoplastic polyimide precursor)
Add 807.0 g of DMF and 106.6 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml and stir in a nitrogen atmosphere. While adding 2.7 g of 4,4′-oxydianiline (hereinafter, also referred to as 4,4′-ODA), adding 4.0 g of BPDA while stirring under a nitrogen atmosphere, and stirring with PMDA, Was added and stirred at 25 ° C. for 1 hour. A solution in which 1.8 g of PMDA was dissolved in 23.1 g of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to the viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 15: Synthesis of thermoplastic polyimide precursor)
Add 807.1 g of DMF and 106.0 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml and stir in a nitrogen atmosphere. While adding 2.7 g of 4,4′-oxydianiline (hereinafter also referred to as 4,4′-ODA), adding 8.0 g of BPDA while stirring in a nitrogen atmosphere, and stirring with PMDA 51.6 g was added and stirred at 25 ° C. for 1 hour. A solution in which 1.8 g of PMDA was dissolved in 22.9 g of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to the viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 16; Synthesis of thermoplastic polyimide precursor)
Add 805.4 g of DMF and 89.7 g of 2,2-bis- [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) to a glass flask with a capacity of 2000 ml and stir in a nitrogen atmosphere. While adding 14.6 g of 4,4′-oxydianiline (hereinafter also referred to as “4,4′-ODA”), adding 8.6 g of BPDA while stirring under a nitrogen atmosphere, stirring PMDA under a nitrogen atmosphere, Was added and stirred at 25 ° C. for 1 hour. A solution prepared by dissolving 1.9 g of PMDA in 24.6 g of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to the viscosity and stirred. When the viscosity reached 1000 poise, addition and stirring were stopped to obtain a polyamic acid solution (thermoplastic polyimide precursor solution).

(Synthesis Example 17; Synthesis of heat-resistant polyimide precursor)
17. In a glass flask having a capacity of 3000 ml, 710.7 g, 4,4′-oxydianiline (hereinafter also referred to as 4,4′-ODA) 20.7 g, p-phenylenediamine (hereinafter also referred to as p-PDA) 18. 6 g of 2,2-bis [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) 28.2 g was dissolved and pyromellitic dianhydride (hereinafter also referred to as PMDA) 31.2 g Was added and stirred for 1 hour to dissolve. To this, 60.9 g of benzophenone tetracarboxylic dianhydride (hereinafter also referred to as BTDA) was added and stirred for 1 hour to dissolve.

  A separately prepared DMF solution of PMDA (PMDA: DMF = 2.7 g: 21.0 g) was gradually added to the reaction solution, and the addition was stopped when the viscosity reached about 3500 poise. Stirring was performed for 1 hour to obtain a polyamic acid solution (heat-resistant polyimide precursor solution) having a solid content concentration of 18% by weight and a rotational viscosity at 23 ° C. of 3500 poise.

( Reference Example 1)
The following chemical dehydrating agent and catalyst were added to the heat-resistant polyimide precursor solution obtained in Synthesis Example 17.
Chemical dehydrating agent: 2.0 moles of acetic anhydride with 1 mole of amic acid unit of heat-resistant polyimide precursor Catalyst: 0.5 mole of isoquinoline with respect to 1 mole of amic acid unit of heat-resistant polyimide precursor From a multi-manifold three-layer coextrusion multilayer die with a width of 520 mm, both outer layers are formed in the order of the thermoplastic polyimide precursor solution obtained in Synthesis Example 3, and the inner layer is the heat-resistant polyimide precursor solution prepared above. The multilayer film having the three-layer structure was continuously extruded and cast so that the copper foil and the thermoplastic polyimide precursor solution were in contact with each other on the mat surface of the copper foil running 50 mm below the T die. As the copper foil, a copper foil HLB made by Nippon Electrolytic Co., Ltd. having a thickness of 12 μm was used. Next, the copper foil with the multilayer film was dried at 140 ° C. for 100 seconds, and then heated in a tenter furnace at 250 ° C. for 20 seconds, 300 ° C. for 20 seconds, and 330 ° C. for 30 seconds to complete imidization. A metal-clad laminate having a good shape with a plastic polyimide layer of 2 μm and a high heat-resistant polyimide layer of 10 μm was obtained. Table 1 shows the raw material molar ratio of the thermoplastic polyimide precursor used for the outer layer.

  The thermoplastic polyimide layer on the side of the obtained metal-clad laminate, to which the copper foil was not bonded, and a 12 μm thick copper foil HLB made by Nippon Electrolytic Co., Ltd. were pressure bonded using a hot roll. The pressure bonding conditions were as follows: protective material (Apical 125 NPI; manufactured by Kaneka Corporation) was used on both sides of the hot roll and the metal-clad laminate, laminating temperature 360 ° C., laminating pressure 176 N / cm (18 kgf / cm) laminating speed 1. It was 0 m / min. The obtained flexible metal-clad laminate was measured for moisture absorption solder heat resistance and metal foil peeling strength. The results are shown in Table 1.

  Subsequently, the thermoplastic polyimide precursor used for the outer layer was applied to a PET film using a comma coater and dried at 150 ° C. for 5 minutes. The coating film was peeled from the PET film, fixed to a metal frame, and heated at 250 ° C. for 5 minutes and further at 350 ° C. for 5 minutes to obtain an adhesive layer polyimide film. The storage elastic modulus of the obtained polyimide film was measured. The results are shown in Table 2.

(Examples 7 to 9 , 12, 14 to 16, Reference Examples 1 to 6, 10, 11 , 13)
Except for changing the type of thermoplastic polyimide used for the outer layer as shown in Table 1 and changing the temperature for completing imidization in Reference Example 1 to 330 ° C. as shown in Table 1, In the same manner as in Reference Example 1, a metal-clad laminate and a polyimide film having an adhesive layer were produced, and moisture-absorbing solder heat resistance, metal foil peeling strength, and storage elastic modulus were measured. The results are shown in Tables 1 and 2.

(Comparative Examples 1-12)
Except for changing the type of thermoplastic polyimide used for the outer layer as shown in Table 1 and changing the temperature for completing imidization in Reference Example 1 to 330 ° C. as shown in Table 1, In the same manner as in Reference Example 1, a metal-clad laminate and a polyimide film having an adhesive layer were produced, and moisture-absorbing solder heat resistance, metal foil peeling strength, and storage elastic modulus were measured.

Claims (10)

A method for producing a metal-clad laminate having at least two or more kinds of polyimide layers on a conductor, wherein at least the two or more kinds of polyimide layers in contact with the conductor are thermoplastic polyimide layers, The thermoplastic polyimide satisfies the following (A) and (B), and forms two or more layers by casting two or more solutions containing a polyimide resin precursor onto a conductor by coextrusion. A metal-clad laminate, wherein a chemical dehydrating agent and a catalyst are contained in at least one of the solutions used for the coextrusion, and the polyimide precursor is imidized at a temperature of 310 to 360 ° C. Manufacturing method:
(A) The thermoplastic polyimide is mainly composed of pyromellitic dianhydride and 2,2-bis- [4- (4-aminophenoxy) phenyl] propane; (i) pyromellitic acid 2 in anhydrous dianhydride other than was 100 mole% tetracarboxylic acid dianhydride component contains 10-50 mol%, and 2,2-bis - other than [4- (4-aminophenoxy) phenyl] propane 5 to 30 mol% of diamine component in 100 mol% of diamine, or (ii) diamine other than 2,2-bis- [4- (4-aminophenoxy) phenyl] propane is 100 mol% of diamine component Containing 5-30 mol%,
(B) The total number of moles of acid dianhydride other than pyromellitic dianhydride and diamine other than 2,2-bis- [4- (4-aminophenoxy) phenyl] propane is 100 moles of acid dianhydride component. % And 100 mol% of the diamine component in a total of 200 mol% is 5 to 50 mol%. The polyimide layer other than the thermoplastic polyimide layer includes at least a heat-resistant polyimide layer,
2. The method for producing a metal-clad laminate according to claim 1, wherein the heat-resistant polyimide layer has a thermoplastic polyimide block component introduced therein.   The method for producing a metal-clad laminate according to claim 1 or 2, wherein the polyimide layer is formed by providing a thermoplastic polyimide layer on both sides of a heat-resistant polyimide layer. On the conductor, a thermoplastic polyimide precursor solution-a heat-resistant polyimide precursor solution-a thermoplastic polyimide precursor solution is cast on the conductor by coextrusion in the order described above, and then dried and fired to obtain a conductor-thermoplastic polyimide layer. -After preparing the laminated body which consists of-heat resistant polyimide layer-thermoplastic polyimide layer, the thermoplastic polyimide layer and the 2nd conductor of the side which is not in contact with the conductor of the said laminated body are heat laminated,
The method for producing a metal-clad laminate according to any one of claims 1 to 3, wherein the heat-resistant polyimide layer has a block component of thermoplastic polyimide introduced therein.   The acid dianhydride other than pyromellitic dianhydride contained in the thermoplastic polyimide is 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 5. The method for producing a metal-clad laminate according to claim 1.   The diamine other than 2,2-bis- [4- (4-aminophenoxy) phenyl] propane contained in the thermoplastic polyimide is 4,4′-oxydianiline. 6. The method for producing a metal-clad laminate according to claim 5.   The method for producing a metal-clad laminate according to any one of claims 1 to 6, wherein the metal-clad laminate has a metal foil peeling strength of 10 N / cm or more when peeled in the direction of 180 degrees. The said thermoplastic polyimide is the storage elastic modulus 1 * 10 < ⁸ > Pa or more in 280 degreeC, and the storage elastic modulus in 350 degreeC is less than 1 * 10 < ⁸ > Pa, The any one of Claims 1-7 characterized by the above-mentioned. Method for producing a metal-clad laminate.   The method for producing a metal-clad laminate according to claim 2 or 4, wherein the heat-resistant polyimide contains a thermoplastic polyimide block component in an amount of 20 to 60 mol% of the total polyimide. The method for producing a metal-clad laminate according to any one of claims 2, 4 and 9, wherein the repeating unit n of the block component of the thermoplastic polyimide is 3 to 99.