JP5566921B2 - Method for manufacturing printed wiring board using aluminum as conductive pattern - Google Patents

Description

The present invention relates to a method for producing a printed wiring board in which the aluminum and the conductive pattern.

  The main conductor material for printed wiring boards has been limited to copper foil for decades. Recently, a thick copper plate having a thickness of 200 to 500 μm has been used as a main conductor of a printed wiring board that requires high current and high heat dissipation. However, printed wiring boards using thick copper as the main conductor are heavy, and particularly in hybrid automobiles and next-generation automobiles that are required to be lightweight, it is desired to reduce the weight of the printed wiring boards.

  Therefore, a circuit board using an aluminum plate as a base material has been proposed for the purpose of weight reduction and heat dissipation. For example, as a circuit board using an aluminum plate, a metal base substrate obtained by bonding and laminating a circuit board having a conductor layer on one side or both sides on an aluminum plate, or laminating and laminating aluminum between conductor layers on both sides. A printed circuit board with a metal core having a three-layer structure has been put into practical use (Patent Document 1). These circuit boards use aluminum for the purpose of heat dissipation, but copper is used as a conductor. Therefore, in a high temperature environment, peeling occurred in the insulating layer for adhesion due to the difference in coefficient of linear expansion between the copper plate as the main conductor and the aluminum plate, and sufficient reliability could not be secured.

  In order to solve such a problem, there is one in which a circuit pattern for mounting an electronic component or the like is formed of an aluminum plate (Patent Document 2). Specifically, an aluminum plate as a conductor is laminated with a prepreg, which is an adhesive having an insulating function, and the surface of the aluminum plate is subjected to an aluminum surface treatment to obtain a zinc-substituted film or a nickel plating film. And a copper plating film, and a copper plating film and a through-hole plating are formed on the copper plating film through pretreatment and chemical copper plating. The copper plating film, the multilayer film, and the aluminum plate Are formed with the circuit pattern.

  However, the invention described in Patent Document 2 requires a complicated processing method of simultaneously and selectively etching an aluminum plate and a copper plating film, and further requires a high liquid management technique at the time of etching. There was a point. Further, in the invention described in Patent Document 2, “the aluminum pattern is formed using the dry film used for forming the copper pattern”, but the aluminum conductor is tapered by side etching, and the nickel- There was a problem that both ends of the copper conductor floated slightly and became undercut.

Japanese Patent Laid-Open No. 09-18140 JP 2007-27618 A

Therefore, the present invention has been made in view of these problems, and does not require a complicated processing method of simultaneously and selectively etching an aluminum plate and a copper plating film, and also has advanced liquid management technology at the time of etching. a main object to provide a method for manufacturing a need for such type printed wiring board.

  In order to achieve the above-mentioned object, the present invention employs the following means.

The printed wiring board according to the present invention is
In a method for manufacturing a printed wiring board, comprising: a core aluminum plate; a prepreg laminated on at least one surface of the core aluminum plate; and a circuit forming aluminum plate laminated on the surface of the prepreg.
The circuit forming aluminum plate includes a conductive pattern forming step of forming a conductive pattern by etching ;
An electroless nickel plating film forming step of forming an electroless nickel plating film after forming a zinc replacement film on at least a part of the surface of the conductive pattern ;
An electroless plating film forming step of forming an electroless copper plating film on at least a part of the prepreg surface, the electroless nickel plating film and the conductive pattern ;
An electrodeposition photoresist film forming step of forming an electrodeposition photoresist film on the surface of the electroless copper plating film ;
And electrodeposited photoresist film removing step of removing the electrodeposited photoresist film only soldering the necessary sites on Suruho Le及 beauty conductors,
It is characterized by including .

The method for producing a printed wiring board according to the present invention is a laminated plate obtained by bonding and laminating a core aluminum plate, a prepreg, and a circuit forming aluminum plate. A conductive pattern is formed by etching the aluminum plate for circuit formation disposed in the outermost layer of the laminated plate prior to the plating step. Therefore, there is an effect that a complicated processing step of selectively etching the aluminum plate and the copper plating film is not required, and it is not necessary to manage the etching solution by selection at that time.

Moreover, since only the aluminum plate for circuit formation is etched according to this invention, a high-density and highly accurate aluminum conductive pattern can be formed easily. Further, since the removal of the saw electrodeposited photoresist film of soldering is required site on Suruho Le及 beauty aluminum conductor performing electrolytic copper plating, as compared with the conventional printed wiring board, requires energy saving, environmentally friendly A printed wiring board can be provided.

  Furthermore, in the present invention, after an aluminum plate for circuit formation is etched to form a conductive pattern, a zinc replacement film, an electroless nickel plating film, an electroless copper plating film, and an electrolytic copper plating film are sequentially formed on the aluminum surface of the conductive pattern. Since it forms, an electrolytic copper plating process can be carried out once. Therefore, a conventional “lamination of zinc replacement coating, nickel plating coating and electrolytic copper plating coating on the surface of the aluminum plate, and pre-treatment and electroless copper plating on the electrolytic copper plating coating again. Compared with the “forming” method, the electrolytic copper plating step can be reduced to one step, which contributes to labor saving in all steps.

  Furthermore, the present invention forms a resist on a relatively thick circuit forming aluminum plate on which a conductive pattern is formed when the electrolytic copper plating is finally performed after etching the circuit forming aluminum plate to form a conductive pattern. There is a need. However, when a normal exposure type dry film is laminated using a vacuum laminator, it cannot be sufficiently adhered to the side edge portion of the conductive pattern and the root portion of the conductive pattern, leaving a cavity or space remaining. Become. Therefore, it is possible to laminate without forming such a defect by forming a film with an electrodeposited photoresist. Thereby, since a conductive pattern can be formed with the comparatively thick aluminum plate for circuit formation, the printed wiring board corresponding to a large current and having high heat dissipation can be provided.

Furthermore, the present invention is Suruho soldering seen electrodeposition photo required site resist film is removed electrolytic copper plating on Le及 beauty aluminum conductor is formed, only the portion required in a single electrolytic copper plating copper plating Therefore, the machining process can be simplified. In addition, since the formation of the copper plating film can be minimized, the weight can be further reduced.

  Furthermore, the present invention provides a printed wiring board that is excellent in weight reduction and high heat dissipation compared to the case where copper is used as a conductor because aluminum plates are used for the core layer and the circuit forming layer. Can do.

Moreover, as the printed wiring board manufactured by the method for manufacturing a printed wiring board according to the present invention, the aluminum plate for the core has a surface roughness Ra of 0.05 μm or less, wherein at least one surface is surface-modified by a molecular adhesion method An aluminum plate may be used, and the circuit-forming aluminum plate may be an aluminum plate whose surface is modified by a molecular adhesion method. The surface modification by the molecular adhesion method may be formation of an electropolymerized film of a triazine dithiol derivative.

  As a surface treatment method for bonding an aluminum plate, there are a buffing method, a caustic treatment method, a chemical conversion treatment method, an alumite treatment method, and the like. Among these, the unsealed state of the anodizing anodizing method is particularly effective for bonding with a normal adhesive. However, when alumite film and non-alumite film are present on the aluminum plate, due to the difference in coefficient of linear expansion, delamination is likely to occur due to thermal shock and temperature change of temperature cycle. It is unsuitable for production. Therefore, the above-described drawbacks can be solved by modifying the surface of the laminated surface by a molecular adhesion method. Furthermore, by forming an electropolymerized film of a triazine dithiol derivative, it is possible to obtain a printed wiring board that has excellent adhesion to a resin base material and excellent heat resistance after adhesion.

Furthermore, as the printed wiring board manufactured by the method for manufacturing a printed wiring board of the present invention, the core aluminum plate is drilled at a position where a through hole is formed, and the hole filling ink is filled by screen printing. It may be formed by polishing excess ink.

  Before processing the aluminum surface, the core aluminum plate is drilled, and the hole filling ink is filled in by screen printing. Conventionally, a plurality of prepregs are used and the core material holes are filled with a prepreg resin that oozes out during the laminating press process. However, such a resin becomes unnecessary. Since no resin from the prepreg is required, a single prepreg can be sufficiently insulated and bonded. Therefore, the thermal resistance of the insulating layer can be greatly reduced, and the heat generated by the circuit components can be efficiently transmitted to the core aluminum.

Furthermore, as the printed wiring board manufactured by the method for manufacturing a printed wiring board according to the present invention, the prepreg and the hole filling ink are resin resins whose composition is 80 to 95% by weight of diallyl phthalate and 20 to 5% by weight of an epoxy resin. A mixture containing 30 to 70% by weight of alumina based on the amount may be used.

  The composition of the prepreg and the hole filling ink is the same. By using the same material for the mixture used for the prepreg and the mixture used for filling the holes, the mutual mixture is melted and mixed together in the lamination press step, so that an integrated insulating mixture can be obtained. Further, by using a mixture in which alumina is added in an amount of 30 to 70% by weight with respect to the resin amount of a resin containing 20 to 5% by weight of an epoxy resin in 80 to 95% by weight of diallyl phthalate, thermal conductivity and insulation are obtained. The reliability can be greatly improved.

Furthermore, as a method for producing a printed wiring board of the present invention, the electroless nickel plating film may be performed in a hypophosphorous acid bath having a phosphorus content of 7 wt% or more and 9 wt% or less.

  By adopting such a configuration, the adhesion of the electroless copper plating film on the electroless nickel plating film is improved.

Furthermore, as a method for producing a printed wiring board of the present invention, after the electroless nickel plating film is formed, the prepreg surface, the electroless nickel plating film, and the conductive pattern may be treated with an alkaline palladium ion catalyst.

  In the process of forming a zinc-substituted film and an electroless nickel plating film on the aluminum surface, performing a catalyst treatment, and sequentially forming the electroless copper plating film and the electrolytic copper plating film, generally the resin before through-hole plating A hydrochloric acid-based palladium catalyst is used for the activation. When a hydrochloric acid-based palladium catalyst is used, the catalyst solution permeates through fine pinholes or the like of the electroless nickel plating film, dissolves aluminum inside, and aluminum deficiency occurs. Therefore, the use of an alkaline palladium ion catalyst can prevent the occurrence of aluminum deficiency.

Furthermore, as a method for producing a printed wiring board of the present invention, after the electrolytic copper plating is formed, the electrodeposited photoresist film may be peeled off and the electroless copper plating film may be removed with an acid aqueous solution.

  Since the electroless copper plating film exposed by peeling the electrodeposited photoresist film is as thin as 0.2 to 0.3 μm, the electroless copper plating film can be easily removed with an acid aqueous solution.

Furthermore, as a method of manufacturing the printed wiring board of the present invention,
A hole filling step of filling in at least a part of the through hole forming region of the core aluminum plate having a surface roughness Ra of 0.05 μm or less, and then filling with a hole filling ink;
A surface modification step of modifying the surfaces of the core aluminum plate and the circuit forming aluminum plate by a molecular adhesion method;
A thermocompression bonding step in which a prepreg having an insulating function is laminated and thermocompression bonded between the core aluminum plate and the circuit forming aluminum plate;
A conductive pattern forming step of forming a conductive pattern by etching the aluminum plate for circuit formation;
An electroless nickel plating film forming step of forming an electroless nickel plating film after forming a zinc replacement film on at least a part of the surface of the conductive pattern;
An electroless plating film forming step of forming an electroless copper plating film on at least a part of the prepreg surface, the electroless nickel plating film and the conductive pattern;
An electrodeposition photoresist film forming step of forming an electrodeposition photoresist film on the surface of the electroless copper plating film;
And electrodeposited photoresist film removing step of removing only electrodeposited photoresist film of soldering site necessary on Suruho Le及 beauty aluminum conductors,
An electrolytic copper plating forming step for forming an electrolytic copper plating at a site where the electrodeposited photoresist film is removed;
A second electrodeposition photoresist film removing step for removing the remaining electrodeposition photoresist film;
An electroless copper plating film removing step of removing the electroless copper plating film with an acid aqueous solution;
It is characterized by including.

  According to the method for producing a printed wiring board of the present invention, a printed wiring board having the above-described effects can be produced.

  According to the method for producing a printed wiring board according to the present invention, a complicated processing method of simultaneously and selectively etching an aluminum plate and a copper plating film is not required, and an advanced liquid management technique is not required at the time of etching. A printed wiring board and a method for manufacturing the printed wiring board can be provided.

It is sectional drawing which shows the outline of a structure of the printed wiring board 100 concerning embodiment. It is an enlarged view of the part of A of FIG. It is a part of flowchart which shows the manufacturing method of the printed wiring board 100 concerning embodiment. It is a part of flowchart (continuation of FIG. 2) which shows the manufacturing method of the printed wiring board 100 concerning embodiment. It is sectional drawing which shows a part of manufacturing process of the manufacturing method of the printed wiring board 100 concerning embodiment. It is sectional drawing which shows a part of manufacturing process (continuation of FIG. 5) of the manufacturing method of the printed wiring board 100 concerning embodiment. It is sectional drawing which shows a part of manufacturing process (continuation of FIG. 6) of the manufacturing method of the printed wiring board 100 concerning embodiment. FIG. 8 is a cross-sectional view showing a part of the manufacturing process of the printed wiring board 100 according to the embodiment (continuation of FIG. 7). FIG. 9 is a cross-sectional view showing a part of the manufacturing process of the printed wiring board 100 according to the embodiment (continuation of FIG. 8). FIG. 10 is a cross-sectional view showing a part of the manufacturing process of the printed wiring board 100 according to the embodiment (continuation of FIG. 9). It is sectional drawing which shows a part of manufacturing process (continuation of FIG. 10) of the manufacturing method of the printed wiring board 100 concerning embodiment. It is a microscope picture which shows the state of a defect | deletion of the internal core aluminum plate which generate | occur | produces when using a hydrochloric acid type palladium catalyst.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The embodiments and drawings described below exemplify a part of the embodiments of the present invention, and are not used for the purpose of limiting to these configurations. In addition, the same or similar code | symbol is attached | subjected to the corresponding component in each figure.

FIG. 1 is a cross-sectional view schematically illustrating a configuration of a printed wiring board 100 according to the embodiment. The printed wiring board 100 according to the embodiment is a core aluminum plate 10 that is a radiator and has a function as a conductor, and prepregs 21 and 22 that have an insulating function laminated on both sides of the core aluminum plate 10. The circuit forming aluminum plates 31 and 32 formed with the conductive patterns 33 respectively laminated on the prepregs 21 and 22 on both sides, and the zinc replacement film 40 and the non-coated film laminated on the surfaces of the circuit forming aluminum plates 31 and 32 in this order. and a electroless nickel plating film 50 (see FIG. 2), furthermore, the soldering of the required site on Suruho Le 1 1, 13 and the conductor (B, range C), electroless copper plating film 60 The electrolytic copper plating film 70 is laminated in this order. Furthermore, Suruho Le 1 1, 13 and soldering the necessary part of the other portion on the conductor (B, in the range other than C, portions other than the through hole) is a solder resist 90 is laminated. In the through hole, only the circuit forming aluminum plates 31 and 32 laminated on the front and back surfaces are electrically connected, and the circuit forming aluminum plates 31 and 32 and the core aluminum plate 10 are electrically connected. And the electrical connection holes 13 that electrically insulate between the circuit forming aluminum plates 31 and 32 and the core aluminum plate 10 laminated on the front and back surfaces. Further, it also has a complete insulation hole 12 that is electrically insulated from both the circuit forming aluminum plates 31 and 32 and the core aluminum plate 10.

  The core aluminum plate 10 is a plate having a thickness of 0.2 mm to 3.0 mm. Preferably, a plate having a thickness of 0.4 mm to 1.0 mm is used from the viewpoint of weight reduction and heat dissipation. The aluminum material to be used is selected from pure aluminum, Al—Cu, Al—Mn, Al—Si, Al—Mg, Al—Mg—Si, Al—Zn—Mg, and the like. . The type to be selected is appropriately selected according to the required characteristics of the product and the purpose of use. From the viewpoint of thermal conductivity and electrical conductivity, a heat-treated pure aluminum system is more preferable.

  Further, the surface roughness Ra of the core aluminum plate 10 used here is 0.05 μm or less in both the rolling direction and the width direction. The surface roughness Ra of a general aluminum plate is 0.5 μm to 0.8 μm in the rolling direction and 0.1 to 0.3 μm in the width direction. Should be used. By using an aluminum plate with an Ra value of 0.05 μm or less, the surface roughness of an aluminum plate that has been subjected to surface modification of aluminum, which will be described later, also becomes an Ra value of 0.05 μm or less, and it has optimal characteristics for high-speed transmission of electrical signals It can be. More preferably, an aluminum plate having an Ra value of 0.03 μm to 0.05 μm may be used.

  Examples of the prepregs 21 and 22 include, but are not limited to, a prepreg made of a glass epoxy resin in which a glass substrate is impregnated with an epoxy resin, an epoxy resin adhesive sheet, an imide-modified epoxy resin adhesive sheet, and the like. The glass substrate may be a woven fabric or a non-woven fabric. Further, in the prepregs 21 and 22, an inorganic filler such as silica or alumina is mixed in the epoxy resin to increase the thermal conductivity between the core aluminum plate 10 and the circuit forming aluminum plate 30, and to improve the heat dissipation characteristics. May be raised. More preferably, the glass base material is impregnated with a mixture in which alumina is added in an amount of 30 to 70% by weight with respect to the resin amount of a resin containing 80 to 95% by weight of diallyl phthalate and 20 to 5% by weight of an epoxy resin. Things are good.

  The circuit forming aluminum plates 31 and 32 have a thickness of 0.1 mm to 1.0 mm. Preferably, the thing of 0.1 mm-0.3 mm is used. The aluminum material used is the same as that of the core aluminum plate 10 and the surface roughness Ra is similarly 0.05 μm or less in both the rolling direction and the width direction. The circuit forming aluminum plates 31 and 32 are laminated on the prepregs 21 and 22 and then etched to form a conductive pattern.

The zinc substitution film 40 and the electroless nickel plating film 50 are plating films formed on the surfaces of the circuit forming aluminum plates 31 and 32 having a conductive pattern. The zincate coating 40, an electroless nickel plating film 50 is plated similarly onto the surface of the circuit forming the aluminum plate 30 in Suruho Le 1 1, 13. This plating film is laminated in order to plate the electroless copper plating 60 on aluminum.

Electroless copper plating 60 is plated to be made in order to form an electrolytic copper plated film 70, after the electrolytic copper plating film 70 is formed to the required site of soldering on Suruho Le 1 1, 13 and conductor It is removed with a low concentration aqueous acid solution. Therefore, the electroless copper plating existing in the final product exists in the lower layer of the electrolytic copper plating film 70.

Electrolytic copper plating film 70, as described above, is formed on the soldering of the required sites on Suruho Le及 beauty aluminum conductor (B, range C).

  The solder resist 90 is laminated on the surface of the laminated board, leaving a soldered mounting portion for mounting electronic components and the like by soldering in the electrolytic copper plating portion, and protects the printed wiring board.

  Next, a method for manufacturing the printed wiring board 100 having the above configuration will be described below with reference to the flowcharts shown in FIGS. First, as shown in FIG. 5a, one aluminum plate having a surface roughness Ra of 0.05 μm or less, which is a heat-treated pure aluminum-based material having a thickness of 0.2 to 3.0 mm, is used as a material for the core aluminum plate 10. Prepare (S1). Then, as shown in FIG. 5b, a drilling process is performed in advance at a location where the insulating hole 11 or the complete insulating hole 12 is formed (S2). Thereafter, as shown in FIG. 5 c, the hole-filling insulating resin 95 is filled into the insulating holes 11 by screen printing using a 100-mesh Tetron screen as the hole-filling ink. The insulating resin 95 for filling holes is not limited, but 30 to 70% by weight of alumina is added to the resin amount of the resin having 20 to 5% by weight of epoxy resin in 80 to 95% by weight of diallyl phthalate. A mixture may be used. Thereafter, hot air at 90 to 110 ° C. is blown for 15 to 25 minutes in a hot air drying furnace to temporarily cure the insulating resin 95 for filling holes, and then hot air at 120 to 140 ° C. is blown for 30 to 50 minutes for curing. Let After that, using a buffing machine, the excess insulating resin 95 for filling the gaps from the insulating holes 11 is removed, and further, hot air at 130 to 160 ° C. is blown for 50 to 60 minutes using a hot air drying furnace to fill the holes. The insulating resin 95 is completely cured (S3).

Next, surface modification of both surfaces of the core aluminum plate 10 is performed (S4). The modification treatment, if example embodiment, caustic treatment, alumite treatment, a treatment by molecular adhesion method. Preferably, surface modification is performed by a molecular adhesion method. In this embodiment, a triazine dithiol derivative coating treatment is performed as a surface modification. At this time, various triazine dithiol derivatives can be used, but preferably 6- (3-triethoxysilylpropylamino) having a dithioltriazinyl group and a triethoxysilyl group in the molecule as a molecular adhesive. -1,3,5-triazine-2,4-dithiol monosodium salt (TES) may be used. In order to perform surface modification, first, degreasing of the surface is indispensable. As the degreasing treatment, the object is achieved by immersing in an organic solvent or an alkaline degreasing solution and spraying these solutions, or by performing ultrasonic treatment in these solutions. Organic solvents include alcohols such as methanol, ethanol, isopropanol, ethylene glycol, propylene glycol, cellosolve and carbitol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as benzene, toluene and xylene, hexane and octane. Aliphatic hydrocarbons such as decane, dodecane and octadecane, esters such as ethyl acetate, methyl propionate and methyl phthalate, ethers such as tetrahydrofuran, ethylbutyl ether and anisole and mixed solvents thereof are effective. The alkaline degreasing solution is composed of alkaline soaps, nonionic surfactants and alkaline earth metals. Preferably, Asahi Cleaner No. 50 (made by Uemura Kogyo Co., Ltd.) may be used. Degreasing can be performed in combination with ultrasonic treatment. Further, atmospheric pressure corona discharge treatment, atmospheric pressure plasma treatment, UV irradiation treatment, and the like are also effective. Further, a reduction treatment may be used in combination as a degreasing step. The reduction treatment may be performed by immersing the degreased aluminum metal plate in a hydrazine aqueous solution. The hydrazine concentration is preferably 1 to 10% by weight, the immersion time is preferably 0.1 to 5.0 minutes, and the immersion temperature is preferably 20 to 60 ° C. This pretreatment condition facilitates electrolytic polymerization on the surface of the aluminum metal plate, which is the next step. Then, it is thoroughly washed with pure water and methanol and dried.

Next, as a polymerization step, an electropolymerized film of a triazine dithiol derivative is formed on the surface of the pretreated aluminum metal plate. The electrolytic solution is obtained by dissolving the triazine dithiol derivative and the supporting electrolyte in pure water. The concentration of the mixed triazine dithiol derivative in the aqueous solution is 0.001 to 5% by weight, preferably 0.01 to 1% by weight. Examples of the supporting electrolyte include NaNO ₂ , NaOH, LiOH, KOH, Na ₂ CO ₃ , Na ₂ SO ₄ , K ₂ SO ₃ , Na ₂ SO ₃ , K ₂ CO ₃ , KNO ₂ , KNO ₃ , NaClO ₄ , _{CH 3 COONa, Na 2 B 2} O 7, NaBO 3, NaH 2 PO 2, (NaPO 3) 6, Na 2 MnO 4, Na 3 SiO 3 and the like. In the present invention, it is preferable to use a supporting electrolyte containing at least one compound of sodium hydroxide (NaOH), sodium nitrite (NaNO ₂ ), and sodium carbonate (Na ₂ CO ₃ ). In particular, a supporting electrolyte containing sodium nitrite (NaNO ₂ ) as an essential component is preferable. That is, a mixed electrolyte of sodium nitrite and sodium hydroxide or a mixed electrolyte of sodium nitrite and sodium carbonate is preferable.

  Next, as the heat treatment step, the polymer film obtained in the polymerization step is subjected to heat treatment. The heat treatment is a process for increasing the film strength by increasing the degree of polymerization of the triazine dithiol derivative film. As the heat treatment conditions, the temperature is 60 to 350 ° C., preferably 80 to 200 ° C. in the air atmosphere, and the treatment time is 5 to 600 minutes, preferably 5 to 120 minutes. Simultaneously with the heat treatment, radiation treatment such as ultraviolet treatment can be used together. If the polymerized film has uneven electrodeposition, it is preferable to carry out water washing and immersion treatment in an alcohol solution after electrolytic polymerization and before heat treatment. As the alcohol solution, alcohol alone or an alcohol solution in which an acrylic acid derivative or a maleic acid derivative is dissolved can be used. Specific examples of the alcohol solution include an ethanol solution in which 10% by weight of acrylic acid-n-hexyl is dissolved, and an ethanol solution in which 10% by weight of maleic acid-n-butyl is dissolved.

  Thus, the core aluminum plate 10 is formed with a triazine dithiol derivative film having a thickness of 100 to 300 nm on the surface having a surface roughness Ra of 0.05 μm or less. The surface contact angle of the aluminum plate shows a value of 40 degrees to 75 degrees, and shows a peel strength of 2.1 KN / m or more.

  On the other hand, two aluminum plates having a surface roughness Ra of 0.05 μm or less, which are pure aluminum heat-treated alloys having a thickness of 0.1 to 1.0 mm, which are materials for the circuit forming aluminum plates 31 and 32, are prepared. (S5). Similarly to the core aluminum plate 10, the circuit forming aluminum plates 31 and 32 are subjected to surface modification by a molecular adhesion method or the like (S6).

  On the other hand, prepregs 21 and 22 are prepared. As the prepregs 21 and 22, the resin amount of the resin containing 80 to 95% by weight of diallyl phthalate having a composition similar to that of the insulating resin 95 for filling a hole in a glass substrate made of glass fiber and 20 to 5% by weight of an epoxy resin. On the other hand, a 0.1 to 0.2 mm glass fiber cloth base epoxy resin impregnated with a mixture added with 30 to 70% by weight of alumina is preferable. Further, a corona discharge treatment is performed so that TES can react with the resin.

  Then, as shown in FIG. 6a, the aluminum plate 31 for circuit formation, the prepreg 21, the aluminum plate 10 for core, the prepreg 22, and the aluminum plate 32 for circuit formation are laminated in this order from the lower layer, and laminated and bonded by hot pressing to form aluminum. A conductor laminate 15 is produced (S7).

  Next, as shown in FIG. 6b, drilling is performed by NC or laser processing or the like at a site where a through hole is required (S8). By this drilling, both the electrical connection hole 13, the insulation hole 11, and the complete insulation hole 12 are opened.

Next, as shown in FIG. 7a, printed circuit board photosensitive films (dry film resists) 41 and 42 are laminated to form an etching resist on the surfaces of the circuit forming aluminum plates 31 and 32 (S9). ). As the printed wiring board photosensitive films 41 and 42, a dry film SA150 and a thickness of 50 μm (manufactured by DuPont) may be used. Then, the photosensitive films 41 and 42 for printed wiring boards are exposed through a negative film (not shown) at a UV amount of 90 mJ / cm ² in a 3 KW UV curing furnace, and 30 ° C. and 1.0% carbonic acid. Development with soda and baking are performed at 150 ° C. for 30 minutes to form a conductive etching resist pattern on the printed wiring board photosensitive films 41 and 42 as shown in FIG. 7b.

  Then, as shown in FIG. 8a, the laminated plate 15 on which the resist pattern is formed is etched to form an aluminum conductive pattern 33 (S10). As an etchant for etching the circuit-forming aluminum plates 31 and 32, 50% by weight of 40Be ferric chloride may be used. In this embodiment, 40Be ferric chloride is used, a liquid volume of 20 liters, an initial liquid temperature of 39 ° C., and a spray type experimental apparatus is used, and the dimensions are 25 cm × 33 cm. Thickness is etched to obtain a laminate 15 in which aluminum forms a conductive pattern.

  After the etching, as shown in FIG. 8b, the printed wiring board photosensitive films 41 and 42 are peeled off (S11). The dry film can be peeled off by spraying, for example, 4% sodium hydroxide (liquid temperature: 40 ° C.) for 2 to 3 minutes.

  Thereafter, as shown in FIG. 9a, zinc is formed on the inner walls of the through holes 11 and 13 of the core aluminum plate 10 and the surface of the conductive pattern of the circuit forming aluminum plates 31 and 21 (including the inside of the through holes 11 and 13). A pretreatment called a zincate treatment using a substitution reaction with aluminum is performed to form a zinc-substituted film 40 having a thickness of 0.1 to 0.2 μm (S12). A uniform and thin electroless nickel plating film 50 of ˜3.0 μm is formed (S13).

  Next, the electroless nickel plating film 50 is surface-treated with an alkaline palladium ion catalyst (S14). As the alkaline palladium ion catalyst, OPC-50 inducer A (Okuno Pharmaceutical Co., Ltd.) may be used. In general, a hydrochloric acid-based palladium catalyst is used to activate the resin before through-hole plating. However, when a hydrochloric acid-based palladium catalyst is used, a fine pinhole or the like of the electroless nickel plating film 50 is used. Then, the catalyst solution penetrates to dissolve the aluminum inside, and the molten aluminum is melted out from the pinholes and the like, and a space in which the aluminum is deficient is generated in the nickel plating film 50 (see FIG. 12). Such a problem can be solved by performing the surface treatment with an alkaline palladium ion catalyst.

  Next, as shown in FIG. 9b, an electroless copper plating film 60 is formed on the entire laminate 15 by electroless copper plating (S15). The electroless copper plating treatment may be a commonly used chemical or process, and a Rochelle salt bath, an EDTA-based chelate bath, or the like can be used. Print Gantt P-DK (manufactured by Atotech Co., Ltd.) and Circvogit 4500 (manufactured by Rohm and Haas Co., Ltd.) are exemplified, but not particularly limited. The electroless copper plating is deposited on the order of 0.1 to 0.5 μm. Preferably, considering the subsequent electroless copper plating removal step, 0.2 μm to 0.3 μm is preferable.

  Next, as shown in FIG. 10a, an electrodeposition photoresist film 45 is formed on the electroless copper plating 60 layer by using an electrodeposition photoresist (S16). Here, the electrodeposition photoresist is used because the resist film can be uniformly formed as long as it is a conductive surface, and the entire three-dimensional shape including the end surfaces and corners can be photoetched. The circuit forming aluminum plates 31 and 32 for forming the conductive pattern 33 have a thickness of 0.1 to 1.0 mm. When a normal exposure type dry film is laminated, a laminate is performed using a vacuum laminator. However, the side edge portion of the conductive pattern 33 and the root portion of the conductive pattern 33 cannot be sufficiently adhered, and a cavity or space remains. However, by forming a film with an electrodeposited photoresist, it is possible to laminate without such drawbacks. Thereafter, as shown in FIG. 10b, exposure and development are performed, and only the through-hole portions 11 and 13 and the mounting region of the electronic component that require soldering are peeled off (ranges B and C). The electrodeposition photoresist used here may be an anionic treatment or a cationic treatment. The former is a method in which the resin is dissociated into anions in the electrodeposition bath, and the resin anions are electrophoresed on the substrate of the substrate to be coated and deposited on the surface of the substrate, and the latter is dissociated into cations. In this method, resin cations are electrophoresed on a substrate of an object to be coated, which is a cathode, and deposit on the substrate surface.

  Then, as shown in FIG. 11a, an electrolytic copper plating film 70 having a thickness of 25 to 30 μm is formed in the through hole portions 11 and 13 that need to be soldered and the mounting region of the electronic component (S17). In order to form the electrolytic copper plating film 70, a copper sulfate bath having a dense deposit, large elongation, low internal stress, and uniform electrodeposition is preferable.

  Next, as shown in FIG. 11b, the electrodeposited photoresist film 45 is peeled off (S18), and the exposed electroless copper plating film 60 is removed by quick etching (S19). For stripping the electrodeposited photoresist, a base such as triethylamine, monoethanolamine, morpholine, ammonia, sodium hydroxide, etc. is used as a neutralizing agent for water-solubilization or water-dispersion in the case of anionic systems. The In the case of a cationic system, for example, an acid such as acetic acid, lactic acid, phosphoric acid, sulfuric acid or the like is used as a neutralizing agent for water-solubilization or water-dispersion. In order to remove the electroless copper plating film 60, since the electroless copper plating film 60 is as thin as 0.2 to 0.3 μm, it can be easily removed by using a low concentration acidic solution.

Finally, as shown in FIG. 1, a solder resist insulating film 90 is formed (S20). The formation of the solder resist insulation film 90 is, for example, a development type one-component solder resist PSR-4000CC02 made by Taiyo Ink Manufacturing Co., Ltd., coated with a viscosity of 65 dpa · s (at 25 ° C.) twice with a target film thickness of 45 μm, Thereafter, it is pre-dried at 80 ° C. for 30 minutes. This pre-dried solder resist is exposed with an ultraviolet light amount of 400 mJ / cm ² , developed with a sodium carbonate solution at 30 ° C. and 1.0%, and then dried at 150 ° C. for 60 minutes to form a solder resist insulating film 90. .

  The printed wiring board 100 according to the embodiment has the following effects. Since the circuit forming aluminum plates 31 and 32 are used as the conductive pattern 33, the printed circuit board 100 can be reduced in weight and heat dissipation compared with the case where copper is used as the conductor. For example, in order to pass an allowable current equivalent to that of a copper foil or a copper plate to the circuit forming aluminum plates 31 and 32 as conductors, the cross-sectional area of the circuit forming aluminum plates 31 and 32 is made of copper. It is necessary to make it 1.6 times that of foil or copper plate. Thus, even if the cross-sectional area of the conductor is 1.6 times, the weight of the conductor is 0.48 times that of a copper foil or a copper plate as a conductor, which is half or less, and the weight can be reduced.

  The printed wiring board 100 forms the conductive pattern 33 by etching the circuit forming aluminum plates 31 and 2 prior to the plating step. Therefore, a complicated processing step of selectively etching the aluminum plate and the copper plating film is not required, and it is not necessary to manage the etching solution by selection at that time.

  Moreover, since only the circuit forming aluminum plates 31 and 32 are etched, a high-density, high-precision aluminum conductive pattern can be easily formed. In addition, since the electrodeposited photoresist film is removed and the electrolytic copper plating is performed only on the through-hole portions 11 and 13 and the portions that need to be soldered, it is possible to save energy compared to the entire copper plating. Can provide environment-friendly printed wiring board.

  Furthermore, after forming the conductive pattern by etching the aluminum plate, the electrolytic copper plating process is used to sequentially form a zinc replacement coating, electroless nickel plating coating, electroless copper plating coating, and electrolytic copper plating coating on the aluminum surface. Can be done once. This contributes to labor saving in all processes.

  Furthermore, since the electrodeposited photoresist film is removed only at the through-hole portion and the portion that needs to be soldered on the conductor to form the electrolytic copper plating, the processing process can be simplified. Moreover, since the formation of the copper film can be minimized, the weight can be further reduced.

Hereinafter, about the printed wiring board manufactured with the printed wiring board manufacturing method of this invention, while giving the preferable Example, as a characteristic about Example 1- Example 5, heat dissipation, the electroless copper on electroless nickel The performance was evaluated for adhesion, adhesion of the photoresist to the conductor, presence or absence of aluminum deficiency in the through hole, and adhesive strength of the laminate. Table 1 shows the materials, processing methods, and characteristics of each example.

  As the aluminum plate for the core, one sheet of A1050 manufactured by Sumitomo Metals Co., Ltd., having a thickness of 0.6 mm is used, and as the prepreg, a glass substrate epoxy resin multilayer printed wiring board R1661 manufactured by Panasonic Electric Works Co., Ltd., thickness 0.2 mm Two sheets (glass transition point 130 ° C., thermal conductivity 0.3 W / mK) were used, and two sheets of A1050 and a thickness of 0.15 mm (manufactured by Sumitomo Light Metal Co., Ltd.) were used as an aluminum plate for circuit formation.

Caustic treatment using sodium hydroxide was performed for surface modification of the core aluminum plate and the circuit forming aluminum plate. These were laminated and pressed to produce a 5-layer laminate having a prepreg and a circuit forming aluminum plate on both sides of the core aluminum plate. As the lamination adhesive press conditions, the temperature was 170 ° C., the pressure was 20 kgf / cm ² , and the press time was 90 minutes.

  A conductive pattern was formed on the aluminum plate for circuit formation of the laminated plate, and then soft etching was performed on the conductive pattern. Resin residue on the surface of the conductive pattern is completely removed by this soft etching. For soft etching, a mixed solution based on sodium hydroxide is used. Next, the smut formed on the surface of the conductive pattern by soft etching is removed by acid cleaning, and after zincate treatment is performed using a zincate treatment agent Substar ZN-111 manufactured by Okuno Pharmaceutical Co., Ltd. An electroless nickel plating film was formed using Nicol LPG-LFM (phosphorus content 2% by weight) manufactured by company.

  Then, after performing a surface treatment with a hydrochloric acid-based palladium catalyst, an electroless copper plating solution is formed with an electroless copper plating solution based on EDTA, and a photoresist film is formed and developed with a dry film SA150 manufactured by DuPont, Only the through-hole portion that requires soldering and the mounting area of the electronic component were peeled off. And the electrolytic copper plating film | membrane with a thickness of 25 micrometers was formed with the copper sulfate bath.

  Further, the photoresist film was peeled off, and the exposed electroless copper plating film was removed by quick etching to form a solder resist insulating film, whereby a printed wiring board of Example 1 was obtained.

  For the printed wiring board of Example 1, instead of using two glass substrate epoxy resin multilayer printed wiring boards R1661 made by Panasonic Electric Works Co., Ltd., having a thickness of 0.2 mm as a prepreg, a thickness of 0.1 mm One was used. In addition, as a modification of the aluminum surface, alumite treatment was performed instead of caustic treatment, and a printed wiring board of Example 2 was obtained. The rest is the same as in the first embodiment.

  Instead of using two glass substrate epoxy resin multilayer printed wiring boards R1661 made by Panasonic Electric Works Co., Ltd. and a thickness of 0.2 mm as prepregs for the printed wiring board of Example 1, DAP / EP (diallyl (Phthalate / epoxy resin) (glass transition point 188 ° C., thermal conductivity 2.1 W / mK), 0.1 mm thick one was used.

  In addition, as an aluminum surface modification, alumite treatment was performed instead of caustic treatment. Furthermore, instead of forming an electroless nickel plating film using Nicolon LPG-LFM (phosphorus content 2% by weight), Nicolon TOM-LFM (phosphorus content 8% by weight) manufactured by Okuno Pharmaceutical Co., Ltd. Used to form an electroless nickel plating film. Thus, a printed wiring board of Example 3 was obtained. The rest is the same as in the first embodiment.

  Instead of using two sheets of glass substrate epoxy resin multilayer printed wiring board R1661, manufactured by Panasonic Electric Works Co., Ltd., having a thickness of 0.2 mm as a prepreg, the DAP / EP (diallyl) was used. (Phthalate / epoxy resin) (glass transition point 188 ° C., thermal conductivity 2.1 W / mK), 0.1 mm thick one was used.

  Further, as a modification of the aluminum surface, a triazine dithiol derivative coating treatment was applied as a molecular adhesion treatment instead of the caustic treatment. Furthermore, instead of forming an electroless nickel plating film using Nicolon LPG-LFM (phosphorus content 2% by weight), Nicolon TOM-LFM (phosphorus content 8% by weight) manufactured by Okuno Pharmaceutical Co., Ltd. Used to form an electroless nickel plating film. Furthermore, instead of forming a photoresist film with a dry film after forming an electroless copper plating, a negative-type photoresist electrodeposition film by Elecoat EU-XC manufactured by Shimizu Corporation was formed, and the printed wiring of Example 4 A substrate was obtained. The rest is the same as in the first embodiment.

  Instead of using two sheets of glass substrate epoxy resin multilayer printed wiring board R1661, manufactured by Panasonic Electric Works Co., Ltd., having a thickness of 0.2 mm as a prepreg, the DAP / EP (diallyl) was used. (Phthalate / epoxy resin) (glass transition point 188 ° C., thermal conductivity 2.1 W / mK), 0.1 mm thick one was used. The rest is the same as in the first embodiment.

  Further, as a modification of the aluminum surface, a triazine dithiol derivative coating treatment was applied as a molecular adhesion treatment instead of the caustic treatment. Furthermore, instead of forming an electroless nickel plating film using Nicolon LPG-LFM (phosphorus content 2% by weight), Nicolon TOM-LFM (phosphorus content 8% by weight) manufactured by Okuno Pharmaceutical Co., Ltd. Used to form an electroless nickel plating film. Furthermore, instead of the surface treatment with the hydrochloric acid-based palladium catalyst after forming the electroless nickel plating film, the surface treatment with an alkaline palladium catalyst was performed. Furthermore, instead of forming a photoresist film with a dry film after forming an electroless copper plating, a negative-type photoresist electrodeposition film by Elecoat EU-XC manufactured by Shimizu Corporation was formed, and the printed wiring of Example 5 A substrate was obtained.

  Referring to Table 1 in which the performance of each of the above examples was evaluated, in Example 1 and Example 2, heat dissipation was 0.2 W / mK, whereas in Example 3, Example 4 and Example 5. It is improved to 2.0 W / mK. This shows that DAP / EP is effective as a prepreg material.

  While the adhesion of electroless copper on electroless nickel in Example 1 and Example 2 is 0.2 kN / m, Example 3, Example 4 and Example 5 are improved to 2.6 kN / m. . Thereby, it can be seen that an electroless nickel plating solution having a phosphorus content of 2% is effective in improving the adhesion, with a phosphorus content of 8%.

  The adhesion of Example 4 and Example 5 is improved with respect to the adhesion of the photoresists of Examples 1, 2 and 3 to the conductor. This shows that the electrodeposition photoresist is effective in improving the adhesion.

  In Example 1, Example 2, Example 3, and Example 4, an aluminum deficiency in the through hole is generated, whereas in Example 5, it is not generated. Thereby, it turns out that an alkaline palladium catalyst is effective in preventing aluminum deficiency.

The lamination adhesive strength of Example 4 and Example 5 is higher than that of Example 2 and Example 3. Moreover, Example 2 and Example 3 are higher than Example 1. Thus, it can be seen that the aluminum surface modification is more effective in the alumite treatment than the caustic treatment, and the molecular adhesion treatment is more effective than the alumite treatment.

  This aluminum conductor printed wiring board is lightweight, can handle a large current, and has a heat dissipation property due to high thermal conductivity. In addition, at the same power consumption, the temperature rise has a characteristic of 1/10 or less of a general printed wiring board. For this reason, power electronics boards with integrated power control, such as in-vehicle DC-DC converters and AC inverters, EPS (electric power steering) control boards, ECUs, wipers, power windows, electric mirrors, and power seats It can be applied to a control board, a wiring board for wiring in a vehicle, a power module board, and the like. Furthermore, this printed wiring board can be applied to a control board for a forklift, a power tool, a motor driving board for an electric bicycle, and the like for industrial equipment.

DESCRIPTION OF SYMBOLS 100 ... Printed wiring board, 10 ... Core aluminum plate, 11 ... Through hole (insulation hole), 12 ... Complete insulation hole, 13 ... Through-hole part (electrical connection hole), 15 ... Laminated board, 21, 22 ... Prepreg, 33 ... conductive pattern, 31, 32 ... aluminum plate for circuit formation, 40 ... zinc replacement coating, 41, 42 ... photosensitive film for printed wiring board, 45 ... electrodeposition photoresist film, 50 ... electroless nickel plating coating, 60 ... Electroless copper plating film, 70 ... Electrolytic copper plating film, 90 ... Solder resist

Claims (9)

In a method for manufacturing a printed wiring board, comprising: a core aluminum plate; a prepreg laminated on at least one surface of the core aluminum plate; and a circuit forming aluminum plate laminated on the surface of the prepreg.
The circuit forming aluminum plate includes a conductive pattern forming step of forming a conductive pattern by etching ;
An electroless nickel plating film forming step of forming an electroless nickel plating film after forming a zinc replacement film on at least a part of the surface of the conductive pattern ;
An electroless plating film forming step of forming an electroless copper plating film on at least a part of the prepreg surface, the electroless nickel plating film and the conductive pattern ;
An electrodeposition photoresist film forming step of forming an electrodeposition photoresist film on the surface of the electroless copper plating film ;
An electrodeposition photoresist film removing step of removing the electrodeposition photoresist film only through the through hole and the part necessary for soldering on the conductor;
A method of manufacturing a printed wiring board, comprising: The core aluminum plate is made of an aluminum plate having a surface roughness Ra of 0.05 μm or less, the surface of which is at least one surface modified by a molecular adhesion method.
2. The printed wiring board manufacturing method according to claim 1, wherein the circuit forming aluminum plate is made of an aluminum plate whose surface is modified by a molecular adhesion method . The method for producing a printed wiring board according to claim 2, wherein the surface modification by the molecular adhesion method is formation of an electrolytic polymerization film of a triazine dithiol derivative. The core aluminum plate is formed by drilling a hole at a position where the through hole is formed, and further filling the hole filling ink by screen printing, and then polishing the excess hole filling ink. Item 4. The method for manufacturing a printed wiring board according to any one of Items 1 to 3. The prepreg and the ink for filling holes are a mixture in which alumina is added in an amount of 30 to 70% by weight with respect to a resin amount of a resin containing 20 to 5% by weight of an epoxy resin in 80 to 95% by weight of diallyl phthalate. The method for manufacturing a printed wiring board according to claim 1, wherein: 6. The printed wiring board according to claim 1, wherein the electroless nickel plating film is performed in a hypophosphorous acid bath having a phosphorus content of 7 wt% or more and 9 wt% or less. Manufacturing method . 7. The surface of the prepreg, the electroless nickel plating film and the conductive pattern are treated with an alkaline palladium ion catalyst after the electroless nickel plating film is formed. The manufacturing method of the printed wiring board as described in a term. The electroless copper plating film is peeled off after the electrolytic copper plating is formed, and the electroless copper plating film is removed with an acid aqueous solution. Manufacturing method of printed wiring board. A hole filling step of filling in at least a part of the through hole forming region of the core aluminum plate having a surface roughness Ra of 0.05 μm or less, and then filling with a hole filling ink;
A surface modification step of modifying the surfaces of the core aluminum plate and the circuit forming aluminum plate by a molecular adhesion method;
A thermocompression bonding step in which a prepreg having an insulating function is laminated and thermocompression bonded between the core aluminum plate and the circuit forming aluminum plate;
A conductive pattern forming step of forming a conductive pattern by etching on the circuit forming aluminum plate;
An electroless nickel plating film forming step of forming an electroless nickel plating film after forming a zinc replacement film on at least a part of the surface of the conductive pattern;
An electroless plating film forming step of forming an electroless copper plating film on at least a part of the prepreg surface, the electroless nickel plating film and the conductive pattern;
An electrodeposition photoresist film forming step of forming an electrodeposition photoresist film on the surface of the electroless copper plating film;
And electrodeposited photoresist film removing step of removing only electrodeposited photoresist film of soldering site necessary on Suruho Le及 beauty conductors,
An electrolytic copper plating forming step for forming an electrolytic copper plating at a site where the electrodeposited photoresist film is removed;
A second electrodeposition photoresist film removing step for removing the remaining electrodeposition photoresist film;
An electroless copper plating film removing step of removing the electroless copper plating film with an acid aqueous solution;
A method of manufacturing a printed wiring board, comprising:

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