WO2004003259A1

WO2004003259A1 - Method of forming polyimide coating containing dielectric filler on surface of metallic material, process for producing copper clad laminate for formation of capacitor layer for printed wiring board and copper clad laminate obtained by the process

Info

Publication number: WO2004003259A1
Application number: PCT/JP2003/008194
Authority: WO
Inventors: Toshiko Yokota; Susumu Takahashi; Hideaki Matsushima; Makoto Dobashi; Takuya Yamamoto
Original assignee: Mitsui Mining & Smelting Co.,Ltd.
Priority date: 2002-06-28
Filing date: 2003-06-27
Publication date: 2004-01-08
Also published as: CN1665966A; JP2004035917A; JP4080799B2; TW200402481A; CN100357496C; US20050161149A1; TWI270580B

Abstract

A method of forming a dielectric layer containing dielectric filler, which is excellent in film thickness uniformity, from a polyimide electrodeposition liquid containing dielectric filler. In particular, a method of forming a polyimide coating containing dielectric filler on a surface of metallic material according to the electrodeposition coating technique, characterized in that as the dielectric filler, use is made of dielectric powder of perovskite structure in approximately spherical form which has an average particle diameter (D1A) of 0.05 to 1.0 μm and a weight cumulative particle diameter (D50), measured in accordance with the laser diffraction scattering type particle size distribution measuring method, of 0.1 to 2.0 μm and further exhibits an aggregation degree, in terms of D50/D1A wherein D50 and D1A represent a weight cumulative particle diameter and an average particle diameter obtained by image analysis, respectively, of 4.5 or less.

Description

Description: A method for forming a polyimide film containing a dielectric filler on the surface of a metal material, a method for manufacturing a copper-clad laminate for forming a capacitor layer for a printed wiring board, and a copper-clad laminate obtained by the method

The present invention relates to a method for forming a polyimide film containing a dielectric filler on the surface of a metal material such as copper, a method for manufacturing a copper-clad laminate for forming a capacitor layer for a printed wiring board, and a copper-clad laminate obtained by the method. Background art

In recent years, it has become common practice to form a capacitor structure on the inner layer of a printed wiring board, especially a multilayer printed wiring board, in the same manner as forming a circuit shape using a copper-clad laminate, and use this as a built-in capacitor. I have been doing it. By forming a capacitor structure in the inner layer of the multilayer printed wiring board, it is possible to omit the capacitor disposed on the outer layer surface, and it is possible to miniaturize and increase the density of the outer layer circuit, and surface mount components It has reduced the number and made it easier to manufacture printed wiring boards with fine pitch circuits.

A capacitor structure using a copper-clad laminate uses a double-sided copper-clad laminate composed of a so-called copper foil layer on each side and a dielectric layer located between the copper foil layers, and a copper layer on both sides. This is performed by etching a foil layer into a capacitor electrode having a desired shape, and forming a capacitor structure in a state where a dielectric layer is sandwiched between capacitor electrodes on both sides at a target position.

Capacitors are required to have the largest possible capacitance as a basic quality. The capacitance (C) of the capacitor is C-ε ε. It is calculated from the equation of (AZ d) (ε is vacuum permittivity). Therefore, in order to increase the capacitance of the capacitor, ① Increase the surface area (表面積) of the capacitor electrode. (2) Reduce the thickness (d) of the dielectric layer. 3) Increase the dielectric constant (ε) of the dielectric layer. Use one of these techniques You just have to use it.

However, regarding the surface area (A) in (1), similar requirements have been imposed on printed wiring boards due to the recent trend of lighter and smaller electronic and electrical β, and within a certain printed wiring board area However, it is almost impossible to broaden the area of the capacitor electrode. Regarding the reduction of the thickness (d) of the dielectric layer in (2), if the dielectric layer includes a skeletal material such as glass cloth, as represented by a pre-preda, there is a skeletal material in the thinning. Therefore, a limitation arises. On the other hand, if the skeletal material is simply omitted using the conventional dielectric layer constituent material, when the capacitor electrode is manufactured by etching, the dielectric layer at the portion where the copper foil layer has been etched away is the shower pressure of the etching solution. Had to be destroyed. From these facts, it has generally been considered to increase the relative dielectric constant (ε) of the dielectric layer in (3).

That is, the structure of the dielectric layer requires a skeletal material such as glass cloth as an indispensable material, and the thickness of the entire dielectric layer is reduced by reducing the thickness of the skeletal material by, for example, non-woven fabric. The use of a resin in which a dielectric filler is dispersed and contained in the material of the dielectric layer has been used to increase the capacitance of the capacitor.

However, as the electric capacity of the built-in capacitor is further increased, the thickness of the dielectric layer is thinner and has excellent thickness accuracy, and is flexible enough to withstand the pressure of the etching solution during etching. It has been awaited to establish a method of manufacturing a copper-clad laminate for forming a capacitor layer having the following characteristics.

To manufacture a copper-clad laminate for forming a capacitor layer that can satisfy such conditions, a dielectric filler-containing polyimide electrodeposition liquid in which a dielectric filler is contained in a polyimide electrodeposition liquid on one side of a copper foil is used. JP-A-2001-158883, forming a dielectric layer containing a dielectric filler in a polyimide resin by an electrodeposition coating method, and further laminating a copper foil to this dielectric layer. Techniques such as those disclosed in the gazette have been studied.

However, forming a polyimide film directly on the copper surface by using an electrodeposition solution with a polyimide electrodeposition solution is extremely advantageous over the coating method in that the film thickness can be reduced. However, in reality, it was quite difficult, and stable operation of polyimide electrodeposition itself was difficult. In addition, the dielectric filler powder is included in the polyimide electrodeposition solution, and the dielectric filler powder particles are contained in the polyimide film to be electrodeposited. It is much more difficult to disperse them evenly, and mass production has not been achieved in actual operations.

Based on the above, the technology for forming a dielectric layer with excellent thickness accuracy using a dielectric filler-containing polyimide electrodeposition solution for forming the dielectric of the copper-clad laminate used to form the capacitor layer Has been sought. Disclosure of the invention

Accordingly, the inventors of the present invention have conducted intensive studies and found that a method of forming a polyimide film containing a dielectric filler on the surface of a metal material such as copper and a copper-clad laminate for forming a capacitor layer for a printed wiring board as shown below. By adopting the board manufacturing method, they came up with the idea of providing an unprecedented copper-clad laminate.

According to the claim, `` a dielectric filler-containing polyimide film is formed on a metal material surface by an electrodeposition coating method using a dielectric filler-containing polyimide electrodeposition liquid in which a dielectric filler is contained in a polyimide electrodeposition liquid. a method of, the dielectric filler, the average particle diameter D _IA is 0 0 5~:.. 1 0 μ a m, weight cumulative particle diameter D _{5 0} by a laser diffraction scattering particle size distribution measuring method 0 .:!. ~ 2 0 i is ni, and, D s oZD t cohesion values represented by a with an average particle diameter D _IA obtained by the weight-cumulative particle diameter D ₅ and the image analysis. A method for forming a dielectric filler-containing polyimide film on a metal material, characterized by using a dielectric powder having a perovskite structure having a substantially spherical shape with a particle size of 4.5 or less. "

The electrodeposition coating method of polyimide resin has been described as being able to form a uniform film on a metal without defects such as pinholes, and can also be used for forming a uniform film on a complicated shape. Conventional polyimides hardly dissolve in solvents, so they were electrodeposited in the form of their precursors, polyamic acid, and dehydrated and cyclized by heating to form a polyimide film. . However, polyamic acid is easily decomposed and unstable. Accordingly, in the present invention, it is preferable to use a polyimide electrodeposition solution for anion electrodeposition coating using a pendant carboxyl group-containing solvent-soluble multi-layer polyimide, such as a composition. Therefore, such a type of polyimide electrodeposition solution can be procured in the factory, and a commercially available polyimide electrodeposition solution can be obtained. Some have very good '1.

When a polyimide film is to be formed on a metal by using the polyimide electrodeposition solution, the electrodeposition property differs depending on the type of the metal. Therefore, it is necessary to prepare a polyimide electrodeposition solution depending on the type of the metal material which is the coated body for forming the polyimide film. In particular, when a polyimide coating is to be formed on a copper material as a metal material by an electrodeposition coating method, if the colloidal particles of the multiblock polyimide in the polyimide electrodeposition solution are not small, uniform and defective It seems that there is a tendency that no good film can be formed. Therefore, it is considered necessary to reduce the size of the colloid particles by increasing the amount of the solvent in accordance with the type of the electrodeposited polyimide. However, since the diameter of the colloidal particles in the polyimide electrodeposition liquid also has a relationship with the thickness of the polyimide film to be formed, it should be adjusted to an appropriate area where the balance between the target polyimide film thickness and electrodeposition properties is finally maintained. We need to do that.

Further, in the case of the present invention, it is considered that the solution property of the polyimide electrolyte should be determined in consideration of the dispersibility of the dielectric filler dispersed and mixed in the polyimide electrolyte. However, at the current technical level, there is a limit to the type of polyimide electrodeposition solution containing multiblock polyimide that can form a uniform and good defect-free polyimide coating on metal materials, and the range of preparation of the composition is also limited. There is.

Accordingly, the present inventors have determined that the powder property of the dielectric filler is improved to ensure good dispersibility of the dielectric filler powder in the polyimide electrodeposition liquid. The dielectric filler used in the present invention is to be dispersed and present in the polyimide film containing the dielectric boiler, and finally functions as a dielectric layer of the capacitor. It is used to increase the electrical capacity of the vehicle. The dielectric filler, B aT I_〇 _{_{3, S rT i0 3, P}} b (Z rT i) 0 3 ( commonly called PZT), P b L a T i 0 3 · P b L a Z r O (aka P LZT), using _{_{S r B i 2 Ta 2 O}} g ( aka SBT) dielectric powder of the complex oxide having a perovskite structure, such as.

The powder properties of the dielectric filler must first be in the range of 0.05 to 1.Ομπι. The particle size referred to here means that the particles form a certain secondary coagulation state, such as the laser diffraction scattering particle size distribution measurement method and the BET method. Indirect measurement, such as estimating the average particle size from the measured values of, cannot be used because the accuracy is inferior, and the dielectric filler is directly observed with a scanning electron microscope (SEM), and the SEM image is analyzed by image analysis The average particle size obtained. In this specification, the particle size at this time is indicated as _DIA . The image analysis of the dielectric filler powder observed using a scanning electron microscope (SEM) in this specification was performed using an IP-1000 PC manufactured by Asahi Engineering Co., Ltd. Circular particle analysis was performed with a threshold value of 10 and a degree of overlap of 20, and the average particle size _A was determined. Further, the weight cumulative particle size D ₅ by a laser diffraction scattering type particle size distribution measuring method. There 0.: - 2. a O ^ m, and, the value of cohesion represented an average particle size 0 obtained by the weight-cumulative particle diameter D ₅₀ and the image analysis in use Ite 0 _50/0 It is required that the dielectric powder has a perovskite structure with a substantially spherical shape and shape of 4.5 or less.

The weight cumulative particle diameter D ₅ 0 by a laser diffraction scattering particle size distribution measurement method is that the particle diameter at weight accumulation of 50% obtained by using a laser diffraction scattering particle size distribution measurement method, the weight-cumulative particle size D _5. The smaller the value of, the larger the ratio of fine particles in the particle size distribution of the dielectric filler powder. In the present invention, this value is required to be 0.1 μπι to 2.0 m. That is, the value of the weight-cumulative particle diameter D ₅₀ in the case of less than 0. 1 H m, whether any manufacturing method is adopted dielectric filler powder, satisfies the cohesion described below significantly the progress of aggregation It is not something. On the other hand, when the value of weight-cumulative particle diameter D ₅ 0 exceeds 1. 0 mu m, the use of as a dielectric Buira for built-in capacitor layer forming a printed wiring board is where an object of the present invention It becomes impossible. That is, the dielectric layer of the double-sided copper-clad laminate used to form the built-in capacitor layer is usually 10 μη! The thickness is about 25 / m, and the upper limit is 2.0 μπι in order to uniformly disperse the dielectric filler.

Measurement of Weight cumulative particle diameter D ₅₀ of the present invention, the dielectric filler powder is mixed and dispersed in Mechiruechi ketone, the solution a laser diffraction scattering particle size distribution measuring apparatus Μ icro Tr ac HRA 9320- X 100 inch (Nikkiso stock Society Neighbors were placed in the circulator and a horizontal test was performed.

The concept of cohesion is used here, but the one adopted for the following reasons: It is. That is, the value of the weight-cumulative particle diameter D _{5 0} obtained by using a laser diffraction scattering particle size distribution measurement method, the it is thought and not observed truly every single size of particulate directly. This is because most of the particles constituting the dielectric powder are not so-called monodispersed powders in which individual particles are completely separated, but a state in which a plurality of particles are aggregated and aggregated. This is because the laser diffraction scattering type particle size distribution measuring method regards the agglomerated particles as one particle (agglomerated particles) and calculates the weight cumulative particle size.

On the other hand, the average particle diameter D _{∑ A} obtained by image-processing the observed image of the dielectric powder observed using a scanning electron microscope is obtained directly from the SEM observation image. The particles are surely caught, and on the other hand, they do not reflect the existence of the aggregation state of the powder particles at all.

Considering the above, the present inventors have determined that the weight cumulative particle size D ₅ of the laser diffraction scattering type particle size distribution measuring method. With an average particle diameter D z _A obtained by image analysis and, D _5.

The value calculated by ZD z _A was taken as the degree of aggregation. That is, on the assumption that the value of the copper powder Niore, Te D ₅ 0 and D j _A in the same bite Tsu bets can be measured with the same accuracy, considering theory described above, determined that there is a cohesive state D ₅ to be reflected in the value. Is likely to be greater than the value of _DIA (similar results can be obtained in actual measurements).

At this time, the value of D _{5 0,} if at all there is no granular state of aggregation of the dielectric filler powder, Yuki approaching the value of the infinitely D _IA, D ₅ is a degree of aggregation. The value of ZD _IA will be close to 1. At the stage when the degree of agglomeration reaches 1, it can be said that this is a monodispersed powder in which the state of agglomeration of the powder particles has completely disappeared. However, in reality, the cohesion degree may show a value of less than 1. It is theoretically considered that in the case of a true sphere, the value does not become less than 1, but in reality, it seems that since the powder is not a true sphere, a value of less than 1 is obtained. is there.

In the present invention, it is required that the cohesion of the dielectric filler powder is 4.5 or less. If the agglomeration degree exceeds 4.5, the agglomeration level of the dielectric filler powder particles becomes too high, and it becomes difficult to uniformly mix the dielectric filler powder with the above-mentioned polyimide electrodeposition solution.

Alkoxide method, hydrothermal synthesis method, oxare Regardless of the production method such as the one-to-one method, a certain coagulated state is inevitably formed, so that a dielectric filler powder that does not satisfy the above coagulation degree can be generated. In particular, in the case of the hydrothermal synthesis method, which is a wet method, formation of an aggregated state tends to occur easily. Therefore, by performing a deagglomeration process of separating the aggregated powder into individual particles, it is possible to set the aggregation state of the dielectric filler powder within the above-described aggregation degree. It is possible.

If the purpose is simply to perform the pulverization work, as a means to perform the pulverization, high-energy ball mill, high-speed conductor impingement type air flow type pulverizer, impact type pulverizer, gauge mill, medium stirring type mill, high water pressure It is possible to use various things such as a pulverizer. However, in order to ensure the mixability and dispersibility of the dielectric filler powder and the polyimide electrodeposition solution, it is necessary to consider the viscosity reduction of the dielectric filler-containing polyimide electrodeposition solution described below. In order to reduce the viscosity of the dielectric filler-containing polyimide electrodeposition liquid, it is required that the specific surface area of the dielectric filler powder be small and smooth. Therefore, even if crushing is possible, the crushing method must not damage the surface of the granules during crushing and increase the specific surface area. Based on such recognition, the present inventors have conducted intensive studies and found that two methods are effective. What is common to these two methods is that it minimizes the contact between the particles of the dielectric filler powder and the parts such as the inner wall of the device, stirring blades, and the grinding media, and reduces the agglomerated particles. This is a method that can be sufficiently disaggregated by causing mutual collision. That is, contact with the inner wall of the device, the stirring blades, the grinding media, etc. damages the surface of the granules, increases the surface roughness, deteriorates the sphericity, and prevents this. is there. Then, by causing sufficient collision between the particles, it is possible to employ a method capable of disintegrating the particles in the agglomerated state and, at the same time, smoothing the surface of the particles due to the collision between the particles. It is.

One is to use a jet mill to pulverize the dielectric filler powder in the agglomerated state. The term "jet mill" here refers to the use of a high-speed air stream to put dielectric filler powder into this air stream and cause the powder particles to collide with each other in this high-speed air stream to perform a pulverizing operation. .

It also breaks the stoichiometry of the dielectric filler powder in the aggregate state. The slurry dispersed in a solvent free from cracks is subjected to a granulation treatment using a fluid mill utilizing centrifugal force. By using the “fluid mill using centrifugal force” here, the slurry flows at high speed in a circular orbit, and the powder particles agglomerated by the centrifugal force generated at this time mutually in the solvent. The powder is then crushed to perform the pulverizing operation. In this way, the slurry that has been pulverized is washed, filtered, and dried to obtain a dielectric filler powder that has been pulverized. By the method described above, it is possible to adjust the degree of agglomeration and to smooth the powder surface of the dielectric filler powder.

The above-described polyimide electrodeposition solution and the dielectric filler are mixed to form a dielectric filler-containing polyimide electrodeposition solution. At this time, the mixing ratio of the polyimide electrodeposition liquid and the dielectric filler was such that the content of the dielectric filler in the dielectric filler-containing polyimide electrodeposition liquid was 50 g. / L to 350 g ZL is desirable.

If the content of the dielectric filler is less than 50 gZL, the dielectric constant of the capacitor is too low to satisfy the relative dielectric constant of 20 currently required in the market. If the dielectric filler content exceeds 350 g / L, the content of the polyimide resin in the dielectric filler-containing polyimide film to be formed will be too low, and the adhesion to the copper foil to be adhered to will be poor. They will be damaged and the formation of capacitors will be difficult.

At this stage, it is preferable to use barium titanate among composite oxides having a perovskite structure in consideration of the production accuracy as a powder at this stage. As the dielectric filler at this time, either calcined titanium titanate or uncalcined parium titanate can be used. In order to obtain a high dielectric constant, it is preferable to use calcined barium titanate. However, if it is selected and used in accordance with the design quality of the capacitor, it is preferable. Most preferably, the dielectric filler of barium titanate has a cubic crystal structure. The crystal structure of barium titanate has a cubic structure and a tetragonal structure. The dielectric filler of the cubic structure is not the same as the dielectric filler of the barium titanate, which has only the tetragonal structure. Place using filler Compared with the case, the dielectric constant of the finally obtained dielectric layer is stabilized. Therefore, it can be said that it is necessary to use at least a barium titanate powder having both a cubic crystal structure and a tetragonal crystal structure.

Using the dielectric filler-containing polyimide electrodeposition solution described above, a dielectric filler-containing polyimide film is formed on the surface of the copper material by an electrodeposition coating method. The dielectric filler is uniformly dispersed without uneven distribution in the polyimide filler-containing polyimide coating, and the dielectric filler-containing polyimide coating itself has a smooth surface and a uniform film thickness without any defects. It becomes. Furthermore, as described in the claim, "a dielectric filler-containing polyimide film is formed on a metal material surface by an electrodeposition coating method using a dielectric filler-containing polyimide electrodeposition solution in which a dielectric filler is contained in a polyimide electrodeposition solution. a method of forming a film, Yukkeru young properly copper material to form a metal seed layer of cobalt to the metal seed layer, a dielectric FILLER one, the average particle diameter D _IA is 0. 0 5~1. Ο a mu Iotaita obtained, the weight-cumulative particle diameter D _{5 0} by laser diffraction scattering particle size distribution measurement method is 0. 1~2. 0 / m, and, by weight cumulative particle diameter D _5. and image analysis containing dielectric powder having an average particle diameter D! _a and perovskite structures in the form of substantially spherical values of cohesion represented by D ₅ ./D! _a is 4.5 or less using for Metal surface by electrodeposition coating using a polyimide electrodeposition solution containing a dielectric filler A method of forming a dielectric filler-containing polyimide film on a metal material characterized by forming a dielectric filler-containing polyimide film. " It is possible to further improve the uniformity of the film thickness.

The method of forming the dielectric filler-containing polyimide film is different from the above-described method of forming the dielectric filler-containing polyimide film in that a metal seed layer of nickel or cobalt is previously formed on the surface of the metal material. Thus, a polyimide film containing a dielectric filler is formed. In other respects, only the formation of a different metal seed layer will be described to avoid duplication of description. The metal material is provided with a very thin metal layer of nickel or cobalt which is excellent in electrodeposition of the polyimide film when using the electrodeposition coating method. This metal layer is called a metal seed layer in this specification. Formation of metal seed layer on metal surface Can employ various methods such as a dry method such as an electrolytic method and a sputtering vapor deposition method, and is not particularly limited.

By providing this metal seed layer, an extremely good polyimide film can be formed even on a copper material surface where it is said to be difficult to form a polyimide film by the electrodeposition coating method. The dielectric filler-containing polyimide film formed on the substrate has a very low possibility of occurrence of defects, and the film thickness uniformity can be remarkably improved.

By using the method for forming a dielectric filler-containing polyimide film on a metal material as described above, the dielectric filler is uniformly dispersed without uneven distribution in the dielectric filler-containing polyimide film. It is possible to reduce the variation in the electrical conductivity depending on the location on the work size plane. The dielectric filler-containing polyimide film itself has a smooth surface and a uniform film thickness, so when forming a capacitor, the electrode material such as copper foil bonded to the dielectric filler-containing polyimide film is formed. Uniform adhesion is easily obtained, and there are no manufacturing defects. By adopting such a method of forming a dielectric layer on the surface of a metal material, the thickness of the polyimide film containing the dielectric filler as the dielectric layer can be made freely, resulting in an excellent electric capacity. Therefore, it is possible to obtain a product having high-level capacitor quality. The technical idea of the method of forming a dielectric filler-containing polyimide film on a metal material described above can be applied to a method of manufacturing a copper-clad laminate for forming a capacitor layer of a printed fine wire board. . That is, the claim includes a method of manufacturing a copper-clad laminate for forming a capacitor layer for a printed wiring board having a layer structure of a first copper foil Z dielectric filler-containing polyimide dielectric layer / second copper foil. in the surface of the first copper foil, the polyimide electrodeposition solution, the average particle diameter D _IA as a dielectric FILLER one is 0. 0 5~1. Ο μ πι , by laser first diffraction scattering particle size distribution measurement method weight cumulative particle diameter D ₅ 0 is 0:.!. ~ 2 0 μ m Ri der, and, D so D with an average particle diameter D _IA obtained by a weight cumulative particle diameter D _{5 0} and the image analysis! _Using a dielectric filler-containing polyimide electrodeposition liquid mixed with a dielectric powder having a substantially spherical shape and a mouth-cube structure having a cohesion degree represented by _A of 4.5 or less, A dielectric filler-containing polyimide coating-coated copper foil with a dielectric filler-containing polyimide coating formed by a coating method, and a second copper foil Polyimide thin film on one surface Using the formed polyimide foil with a polyimide thin film, the dielectric filler-containing polyimide coating surface of the dielectric filler-containing copper foil and the polyimide thin film surface of the copper foil with the polyimide thin film are in contact with each other. Copper foil for forming a capacitor layer for a printed wiring board with a layered structure of the first copper foil Z dielectric filler-containing polyimide dielectric layer / second copper foil A method for manufacturing a laminate. "

FIG. 1 schematically shows the flow of this manufacturing method. In addition, the drawings are extremely schematically shown as cross-sections so that the description of the manufacturing method is easy to understand, and the thickness, size, and the like do not accurately reflect the values of the objects actually implemented. This is clearly stated here. Since the basic concept is the same as the above-mentioned method of forming a dielectric filler-containing polyimide film on a metal material, only the procedure for manufacturing a copper-clad laminate will be described.

This manufacturing method will be described below with reference to FIG. The dielectric filler-containing polyimide coating 2 is formed on the surface of the first copper foil CF1, and the resulting dielectric-filled polyimide foil-coated copper foil. At this time, the dielectric filler-containing polyimide electrodeposition liquid used for forming the dielectric filler-containing polyimide coating 2 was added to the polyimide electrodeposition liquid as a dielectric filler having an average particle diameter D of 0.05 to It is 1.0 μm and has a cumulative weight particle size D ₅ determined by laser diffraction / particle size distribution measurement. There 0. 1 to 2. O iz is m, and, D ₅ with an average particle diameter D _IA obtained by a weight cumulative particle diameter D _{5 0} and image analysis. / D! A dielectric powder having a perovskite structure having a substantially spherical shape and a cohesion value represented by A of 4.5 or less was added and uniformly mixed.

Then, using the dielectric filler-containing polyimide electrodeposition solution, a dielectric filler-containing polyimide coating-formed copper foil 3 having a dielectric filler-containing polyimide coating 2 formed by an electrodeposition coating method is obtained.

On the other hand, the polyimide thin film 4 with a thickness of 1 to 3 μm is to be left on one surface of the second copper foil CF2, taking solvent removal and resin flow occurring during drying and pressing into consideration. In addition, a copper foil 5 with a polyimide thin film having a thickness of about two to three times the intended thickness is manufactured. At this time, a thickness of about 2 to 3 times the final thickness is applied to one side of the second copper foil CF2 by electrolytic coating using a polyimide electrodeposition solution not containing the dielectric filler. Thus, a polyimide thin film 4 is formed. The polyimide thin film 4 functions as a binder at the time of bonding with the dielectric filler-containing polyimide film 2 described below. If the final polyimide thin film 4 after pressing is less than 1 m, it is difficult to sufficiently cover the uneven adhesive surface of the copper foil, and the thickness of the polyimide thin film 4 is 3 zm or more. In this case, since the polyimide thin film 4 itself does not contain a dielectric filler, the dielectric constant of the finally formed dielectric layer is significantly reduced.

Dielectric filler-containing polyimide film 2 of dielectric filler-containing polyimide film 3 of copper foil 3 with dielectric filler-containing polyimide film and polyimide thin film 5 obtained as described above, The first copper foil CF 1 / dielectric filler-containing polyimide dielectric layer 6 / second copper foil CF 2 Thus, a copper-clad laminate for forming a capacitor layer for a printed wiring board having the above layer configuration can be obtained. Further, in another claim, there is provided a method for manufacturing a copper-clad laminate for forming a capacitor layer for a printed wiring board having a layer structure of a first copper foil Z dielectric filler-containing polyimide dielectric layer Z second copper foil. In the method, a metal shield layer of nickel or cobalt is formed on the surface of the first copper foil, and the surface on which the metal seed layer is formed has a polyimide electrodeposition solution and an average particle size A as a dielectric filler. 0.0 5 to 1. an O wm, the weight-cumulative particle diameter D ₅ 0 by turbulent particle size distribution measuring method dispersion laser diffraction is 0. 1 ~ 2. 0 m, and a weight cumulative particle diameter D _5. dielectric powder having a perovskite structure in the form of substantially spherical values of cohesion represented by D ₅ .ZD j a is 4.5 or less with an average particle diameter D _IA obtained by an image analysis With a dielectric filler-containing polyimide electrodeposition solution mixed with Using a dielectric filler-containing polyimide coating-coated copper foil having a polyimide coating formed thereon, and a polyimide thin-film-forming copper foil having a polyimide thin film formed on one surface of a second copper foil, A first copper foil Z dielectric filler-containing polyimide dielectric, wherein the dielectric layer filler-containing polyimide coating surface and the polyimide thin film surface of the copper foil with the polyimide thin film are overlapped so as to be in contact with each other. Body Layer Z A method for producing a copper-clad laminate for forming a capacitor layer of a printed wiring board having a layer structure of second copper foil. " This FIG. 2 schematically shows the flow of the manufacturing method.

The method of manufacturing the copper-clad laminate for forming the capacitor layer of the printed wiring board is basically the same as the method of manufacturing the copper-clad laminate for forming the capacitor layer of the printed wiring board described above. Only in that In the case of the first copper foil C F 1, the metal seed layer S is formed on the surface of the first copper foil C F 1 before the formation of the dielectric filler-containing polyimide film 2. Similarly, in the case of the second copper foil CF2, the metal seed layer S is formed on the surface of the second copper foil CF2 before forming the polyimide thin film 4. Since the method of forming the metal seed layer S is the same as the method of forming the dielectric film-containing polyimide coating on the metal material described above, redundant description is omitted to avoid duplication.

The bonding surface of the first copper foil CF1 and the second copper foil CF2 used in the above manufacturing method is a surface used for bonding with the dielectric layer 6, and usually causes the dielectric layer 6 to exert an anchor effect. With irregularities for the purpose. In the drawing, it is described as having fine copper particles attached. The copper foil used for the copper-clad laminate constituting the capacitor layer preferably uses a product whose copper foil has a roughened surface as flat as possible in order to keep the thickness of the dielectric layer uniform. Therefore, it is preferable to use very rope mouth file (VLP) copper foil, rolled copper foil, or the like. The dielectric filler 1F is shown as a black dot in the drawing.

Certainly, it is also possible to manufacture copper-clad laminate 用 by using two pieces of the above-mentioned copper foil with a dielectric filler-containing polyimide coating and overlaying and pressing each dielectric filler-containing polyimide coating. It is. However, by employing the above-described method of manufacturing a copper-clad laminate, the dielectric layer containing the dielectric filler can be manufactured to have an arbitrary thickness and a uniform thickness. It became possible to form a dielectric layer. In addition, the dielectric layer of the copper-clad laminate according to the present invention is a polyimide film in which a dielectric filler is dispersed, so that the dielectric layer is embrittled because of its high strength and flexibility characteristic of polyimide resin. This prevents the occurrence of damage due to the etchant shower when forming the capacitor circuit. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic cross-sectional view illustrating a manufacturing flow of a copper-clad laminate for forming a capacitor layer of a printed wiring board. FIG. 2 is a schematic cross-sectional view illustrating a manufacturing flow of a copper-clad laminate for forming a capacitor layer of a printed wiring board. FIG. 3 is an optical microscope observation image of a copper-clad laminate for forming a capacitor layer of a printed wiring board. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described through the manufacture of a copper-clad laminate for forming a capacitor layer of a printed wiring board. First Embodiment In this embodiment, a copper-clad laminate 1 for forming a capacitor layer of a printed wiring board is manufactured according to the manufacturing flow shown in FIG. In the present embodiment, as the first copper foil C F 1, a belly rope mouth file (V L P) copper foil having a nominal thickness of 35 / im was used.

First, before the dielectric filler-containing polyimide film 2 is formed on the surface of the first copper foil CF1, the surface of the first copper foil CF1 is cleaned at the stage of FIG. 1 (a-1). A pickling treatment and an electrolytic degreasing treatment were performed. The pickling treatment was performed by immersing the first copper foil C F 1 in a 1 M sulfuric acid solution at a liquid temperature of 25 ° C. for 1 minute, followed by washing with water.

Then, using an aqueous solution of 20 g ZL sodium carbonate and 5 g ZL trisodium phosphate, the solution temperature was set to 50 ° C, and the electrolytic current was 5 A / dm2 for 1 minute. Was degreased, washed with water and dried.

Next, preparation of a dielectric filler-containing polyimide electrodeposition solution will be described. In this embodiment, 25 wt% of cyclohexanone was added to the polyimide electrodeposition solution Q-ED-22-10 manufactured by PI Technology Laboratory Co., Ltd. to adjust the colloid particle size. Was used.

Barium titanate powder, which is a dielectric filler F having the following powder properties, was mixed and dispersed in the polyimide electrodeposition solution. The mixing ratio was such that barium titanate was 80 wt% of the solid content of the polyimide in the high-speed dielectric filler-containing polyimide electrodeposition solution. Powder properties of dielectric filler

Average particle size (D _IA ) 0.25 μπχ

Weight cumulative particle size (D ₅₀ ) _0.5 m

Using cohesion _{_{(D 50 / D IA) 2.}} 0 or more way dielectric filler-containing polyimide electrodeposition solution, prepared prior Symbol first bonding surface of the copper foil CF 1, dielectric in electrodeposition coating method Body containing polyimide coating

Formed two. The electrodeposition conditions at this time were as follows: the temperature of the dielectric filler-containing polyimide electrodeposition solution was 25 ° C, the first copper foil CF 1 was the anode, the stainless steel plate was the cathode, and a DC voltage of 5 V was applied. By performing electrolysis for 6 minutes, the polyimide resin and the dielectric filler F were simultaneously electrodeposited on the copper foil surface to form a dielectric filler-containing polyimide film 2 having a thickness of about 8 μπι, which was washed with water.

Then, finally, as a drying treatment, the drying was carried out by holding the film in an atmosphere at a temperature of 120 ° C. for 30 minutes, and further raising the temperature of the atmosphere to 180 ° C. and holding it for 30 minutes. In this way, a copper foil 3 with a polyimide coating containing a dielectric filler as shown in FIG. 1 (a-2) was produced.

On the other hand, the second copper foil CF 2 is made of the same copper foil as the first copper foil CF 1, is subjected to the pickling treatment and the degreasing treatment at the stage of FIG. Then, using the above-mentioned polyimide electrodeposition solution containing no dielectric filler,

A 10 μm-thick polyimide thin film 4 was formed on the surface of the bonding surface so as to have a thickness of 3 μm. Then, as a final drying process, in the same temperature atmosphere of 120 ° C as described above,

The temperature was maintained for 30 minutes, and the ambient temperature was further increased to 180 ° C. and the temperature was maintained for 30 minutes. Thus, as shown in FIG. 1 (b-2), a copper foil 5 with a polyimide thin film was manufactured.

The dielectric filler-containing polyimide coating layer 2 of the dielectric filler-containing polyimide coating-coated copper foil 3 and the polyimide thin film 4 of the polyimide foil-coated copper foil 5 obtained as described above are shown in FIG. 1 (c). As described above, the copper-clad laminate 1 for forming the capacitor layer of the printed wiring board was manufactured by facing and laminating. The laminated strip at this time The conditions were as follows: the press pressure was 5 kg / cm ² , the press temperature was initially set to 250 ° C., the temperature was heated for 30 minutes, the temperature was raised to 300 ° C., and the temperature was maintained for 30 minutes.

FIG. 3 shows a cross section of the copper-clad laminate 1 for forming a capacitor layer of the printed wiring board thus obtained, which was observed with an optical microscope. At this time, the dielectric layer 6 formed by laminating the dielectric filler-containing polyimide film layer 2 and the polyimide thin film 4 has an average thickness of 10 M Hi, and as shown in FIG. You can see that it has a thickness.

The first copper foil C F1 and the second copper foil C F2 on both surfaces of the copper-clad laminate 1 manufactured as described above were leveled, and a dry film was stuck on both surfaces to form an etching resist layer. Then, the capacitor circuit was exposed and developed on the etching resist layers on both sides to form an etching pattern. After that, circuit etching was performed with a copper chloride etching solution, and the etching resist was stripped to produce a capacitor circuit. During this etching, the dielectric layer 6 was not broken by the shower pressure of the etchant, and a printed wiring board in a good state was obtained.

Then, as a result of measuring the relative permittivity of the dielectric layer 6 constituting the capacitor circuit, a very good value of ε = 24.7 was obtained, and it was found that a capacitor having a high capacitance was obtained. Second Embodiment In this embodiment, a copper clad laminate 1 for forming a capacitor layer of a printed wiring board was manufactured according to the manufacturing method shown in FIG. In the present embodiment, similarly to the first embodiment, a belly rope mouth file (VLP) copper foil having a nominal thickness of 35 was used as the first copper foil CF1.

First, the steps up to the pickling treatment and the degreasing treatment of the first copper foil CF1 performed in the stage of FIG. 2 (a-1) are the same as those of the first embodiment. 2) A nickel metal seed layer S was provided as shown in FIG. 2), and then a dielectric filler-containing polyimide coating 2 was formed on the surface of the first copper foil CF1 as shown in FIG. The body foil-containing copper foil with a polyimide coating 3 ′ was used. At this time, the formation of the dielectric filler-containing polyimide film 2 after the provision of the metal shield layer S is also the same as in the first embodiment. Therefore, only the method for forming the Eckel metal seed layer s will be described. The formation of the metal seed layer S in the present embodiment is performed using a nickel pet bath containing 240 g ZL of nickel sulfate hexahydrate, 45 g / L of nickel chloride hexahydrate, and 30 g ZL of boric acid, at pH 5, liquid temperature 55 ° C, in the electrolysis of 1 second at a current density of ² a / dm 2, about

The 10 oA nickel layer was formed as the metal seed layer s.

—The second copper foil CF2 uses the same copper foil as the first copper foil CF1, and performs pickling and degreasing at the stage of Fig. Then, a metal seed layer S is formed as shown in FIG. 2 (b-2), and thereafter, about 2-3; A 10 μm-thick polyimide thin film 4 was formed on the surface of the bonding surface so as to have a thickness. Then, the final drying treatment was performed by keeping the same temperature of 120 ° C. for 30 minutes as described above, and further raising the temperature of the atmosphere to 180 ° C. and holding for 30 minutes. In this way, as shown in FIG. 2 (b-3), a copper foil 5 ′ with a polyimide thin film was manufactured.

The dielectric filler-containing copper foil 3 ′ of the dielectric filler-containing polyimide film 3 ′ obtained as described above, and the polyimide thin film 4 of the copper foil 5 with the polyimide thin film 5 and the polyimide thin film 4 of FIG. As shown in c), by facing and laminating, a copper-clad laminate 1 for forming a capacitor layer of a printed wiring board was manufactured. The lamination conditions at this time are the same as those in the first embodiment, and thus description thereof will be omitted here to avoid redundant description.

Copper-clad laminate for forming a capacitor layer of a printed wiring board thus obtained

When the cross section of 1 ′ is observed with an optical microscope, it is impossible to observe the metal seed layer s because it is extremely thin, so that the same state as shown in FIG. 3 can be observed. Accordingly, the use of an optical microscope for the copper-clad laminate 1 to omit a section observation state is omitted. However, also in this embodiment, the dielectric layer 6 formed by laminating the dielectric filler-containing polyimide coating layer 2 and the polyimide thin film 4 has an average thickness of 9.5 μm, which is very smooth. It can be seen that it has a uniform thickness.

The first copper foil CF1 and the second copper foil CF2 on both sides of the copper-clad laminate 1 manufactured as described above are leveled, and a dry film is stuck on both sides thereof. Layer was formed. A 1 cm × 1 cm capacitor circuit was exposed and developed on the etching resist layers on both sides to form an etching pattern. Thereafter, the circuit was etched with a copper chloride etchant, the etching resist was stripped, and a capacitor circuit was manufactured. During the etching, the dielectric layer 6 did not rupture due to the etching solution shear pressure, and a printed wiring board in a good state was obtained.

Then, as a result of measuring the relative permittivity of the dielectric layer 6 constituting the capacitor circuit, a very good value of ε = 33.6 was obtained, and it was found that a capacitor having a high capacitance was obtained. Industrial applicability

By using the method of forming the dielectric filler-containing polyimide coating according to the present invention on the surface of the metal material using the electrodeposition coating method, it is possible to form a thin, uniform and smooth dielectric filler-containing polyimide coating. When used as a dielectric layer of a capacitor, a high dielectric constant can be achieved, and as a result, the capacitance of the capacitor can be improved, and the quality stability can be significantly improved due to fewer defects. become. By applying the same technical concept to manufacture copper-clad laminates that use a dielectric filler-containing polyimide film as the dielectric layer, a high-quality component material for the capacitor layer of the printed wiring board can be obtained. Can be provided.

Claims

The scope of the claims

1. A method for forming a dielectric filler-containing polyimide film on a metal material surface by an electrodeposition coating method using a dielectric filler-containing polyimide electrodeposition liquid in which a dielectric filler is contained in a polyimide electrodeposition liquid;

The dielectric filler, the average particle diameter A is from 0.05 to 1.0 / A zm, weight cumulative particle diameter D ₅₀ by laser first diffraction scattering particle size distribution measuring method 0. 1~2. Ομηι Der Ri, and, D ₅ with an average particle diameter D _IA obtained by a weight cumulative particle diameter D ₅₀ and the image analysis. A dielectric powder having a substantially spherically shaped perovskite structure having an agglomeration degree of 4.5 or less expressed by ZD _t A; Method of forming containing polyimide coating.

2. A method for forming a dielectric filler-containing polyimide film on a metal material surface by an electrodeposition coating method using a dielectric filler-containing polyimide electrodeposition liquid in which a dielectric filler is contained in a polyimide electrodeposition liquid;

Form a nickel seed or co-part metal seed layer on copper material,

On the metal seed layer, a dielectric filler, the average particle diameter D of 0.05~:.! L 0 a Myupaiiota, 0. weight cumulative particle diameter D ₅₀ by laser diffraction scattering particle size distribution measuring method; ~ 2 . 0 m, and and substantially the value of cohesion represented by D ₅ o / D _a with an average particle diameter D _{r a} obtained by the weight-cumulative particle diameter D ₅₀ and the image analysis is 4.5 or less A dielectric filler containing a dielectric powder having a perovskite structure with a spherical shape is used. A polyimide filler-containing polyimide electrodeposition solution is used to form a polyimide filler-containing polyimide film on a copper material surface by electrodeposition coating. Characteristic method for forming a dielectric filler-containing polyimide film on a metal material surface.

3. The dielectric filler content on the surface of the metal material according to claim 1 or 2, wherein the content of the dielectric filler in the dielectric filler-containing polyimide electrodeposition liquid is 50 g / L to 350 gZL. A method for forming a polyimide film.

4. The dielectric filler mono-containing polyimide on the surface of a metal material according to any one of claims 1 to 3, wherein the dielectric filler is calcined barium titanate or uncalcined barium titanate. The method of forming the coating.

5. The crystal structure of the dielectric filler is only cubic or a mixture of cubic and tetragonal. 5. The method for forming a polyimide film containing a dielectric filler on a surface of a metal material according to any one of claims 1 to 4, wherein the film is parium titanate having a structure.

6. First copper foil In a method of manufacturing a copper-clad laminate for forming a capacitor layer for a printed wiring board having a layered structure of a Z dielectric filler-containing polyimide dielectric layer / second copper foil, on the surface, the polyimide electrodeposition solution, the average particle diameter D _IA as a dielectric filler 0 0 5:.. a L 0 mu m, a weight cumulative particle diameter D ₅ 0 by a laser diffraction scattering particle size distribution measurement method from 0.1 to 2. a 0 _mu m, and a weight cumulative particle diameter D _5. And average particle size D obtained by image analysis! A and D ₅ . ZD! An electrodeposition coating method using a dielectric filler-containing polyimide electrodeposition liquid mixed with a dielectric powder having a substantially spherical shape and a perovskite structure having a cohesion value of 4.5 or less. Using a copper foil with a polyimide filler-containing polyimide coating formed with a dielectric filler-containing polyimide coating with a polyimide foil with a polyimide thin film formed on one surface of a second copper foil,

It is characterized in that the dielectric filler-containing polyimide coating surface of the dielectric filler-containing polyimide coating copper foil and the polyimide thin film surface of the polyimide thin film-containing copper foil are overlapped and laminated so that they come into contact with each other. A method for producing a copper-clad laminate for forming a capacitor layer for a printed wiring board having a layered structure of the first copper foil Z dielectric filler-containing polyimide dielectric layer / second copper foil.

7. The method for manufacturing a copper-clad laminate for forming a capacitor layer for a printed wiring board, comprising a layer structure of a first copper foil / a dielectric filler-containing polyimide dielectric layer / a second copper foil. on the surface of, a metal seed layer of nickel or cobalt, the surface forming the metal seed layer, and the polyimide electrodeposition solution, the average particle size D _a as dielectric filler 0 0 5:.. 1 0 μm, and the cumulative weight particle size D ₅ by a laser diffraction scattering particle size distribution measuring method. Is 0.1 to 2.Ομηι and the cumulative weight particle size D ₅ . Dielectric powder having a D ₅ OZD t values of cohesion represented by _A is 4.5 or less perovskite structure in the form of substantially spherical is used the average particle diameter D _r A obtained by image analysis and Using a dielectric filler-containing polyimide electrodeposition solution obtained by mixing a dielectric filler-containing polyimide coating with an electrodeposition coating method, Using a copper foil with a polyimide thin film having a polyimide thin film formed on one surface of the second copper foil,

It is characterized in that the dielectric filler-containing polyimide coating surface of the dielectric filler-containing polyimide coating copper foil and the polyimide thin film surface of the polyimide thin film-containing copper foil are overlapped and laminated so that they come into contact with each other. A method of manufacturing a copper-clad laminate for forming a capacitor layer of a printed wiring board having a layered structure of a first copper foil Z dielectric filler-containing polyimide dielectric layer / second copper foil.

8. The capacitor layer of the printed wiring board according to claim 6 or 7, wherein the content of the dielectric filler in the dielectric filler-containing polyimide electrodeposition liquid is 50 g / L to 350 g / L. A method for producing a copper-clad laminate for forming.

9. The copper clad laminate for forming a capacitor layer of a printed wiring board according to any one of claims 6 to 8, wherein the dielectric filler is calcined parium titanate or uncalcined barrier titanate. Plate manufacturing method.

10.The printed wiring board according to any one of claims 6 to 9, wherein the dielectric filler is a palladium titanate having a crystal structure of a cubic crystal alone or a mixed state of a cubic crystal and a tetragonal crystal. A method for producing a copper-clad laminate for forming a capacitor layer.

11. A copper-clad product for forming a capacitor layer of a printed wiring board obtained by the method for producing a copper-clad laminate for forming a capacitor layer of a printed wiring board according to any one of claims 6 to 10.