JP2009164340A - Stereoscopic circuit board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a stereoscopic circuit board, which can bond a conductor metal to a substrate with a high peel strength, having a high degree of circuit designing flexibility, and can be manufactured easily and efficiently. <P>SOLUTION: The method comprises: a substrate forming step S1 of forming an electrically-insulating thermoplastic heat-resistant film into a three-dimensional substrate 12; a circuit mask mounting step S2 of mounting a mask 20 which is formed into a three-dimensional shape to cover the surface of a portion corresponding to an electrically-insulating portion I of a conductive circuit C provided on the surface of the substrate 12; a conductive paste applying step S3 of applying conductive paste 14a to the conductive circuit (C) portion which is an unmasked portion of the substrate 12, removing the mask 20, curing the conductive paste 14a, and thus obtaining a conductive coat layer 14; and an electroplating step S4 of electroplating conductor metal on the surface of the conductive coat layer 14 and obtaining a conductor plating layer 16. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a three-dimensional circuit board in which a conductive circuit is provided at a necessary position on the surface of a base material formed into a three-dimensional three-dimensional shape and a method for manufacturing the same.

  3D circuit boards with conductive circuits provided at the necessary locations on the surface of a base material molded into a three-dimensional shape can dramatically improve the degree of freedom in electronic device design. Has attracted attention from various fields.

Therefore, conventionally, the following techniques have been proposed as a method of manufacturing this three-dimensional circuit board.
(1) After forming a substrate by molding a thermosetting resin such as an epoxy resin or an unsaturated polyester resin containing a catalyst for electroless plating or a thermoplastic resin such as polyetherimide or polyphenylene sulfide into a three-dimensional shape A method of forming a conductive circuit pattern by subjecting the surface of the substrate to electroless plating of a conductive metal such as copper and selectively removing a predetermined portion of the plating layer by a photolithography method [subtractive method].
(2) A thin conductive metal film is formed on the surface of a three-dimensional substrate, which is a synthetic resin molded product capable of metal coating, by chemical plating (electroless plating) in advance, and then applied to a predetermined portion of the conductive metal film. A method [subtractive method] in which only a portion to be a conductive circuit is left by irradiating laser light to remove the conductive metal film in the portion (see, for example, Patent Document 1).
(3) After printing a conductive circuit pattern with conductive paste using a printing method such as screen printing, offset printing, letterpress printing, or intaglio printing on the substrate, the energy on the entire substrate or the printed surface of the substrate ( A method of manufacturing a three-dimensional circuit board using a method of fixing the conductive circuit pattern by irradiation (heating, light irradiation, etc.) (for example, see Patent Document 2) [additive method].

If these techniques are used, a 3D circuit board can be obtained by forming a conductive circuit pattern on the surface of a base material formed into a three-dimensional shape.
JP-A-6-164105 JP 2001-15893 A

  However, the above-described conventional methods (1) to (3) for manufacturing a three-dimensional circuit board have the following problems.

  That is, in the method of manufacturing a three-dimensional circuit board according to the above (1), when the three-dimensionally formed substrate has large unevenness, it is difficult to uniformly expose the resist applied on the substrate when exposing the resist applied on the substrate. There is a problem that it can be applied only to a substrate whose three-dimensional shape is close to a plane. In addition, there is a problem that facilities (especially an exposure apparatus) used for manufacturing a general planar printed circuit board cannot be used, and a separate facility must be installed. Furthermore, in this example, the surface of the base material is electrolessly plated with a conductive metal so as to directly form a metal foil film that becomes the base of the conductive circuit. In a 3D circuit board where the adhesive strength (more specifically, peel strength) is weak and the stress at the time of thermal expansion tends to concentrate on the bent part or corner part, it is affected by heat etc. when soldering electronic components. When a stress is applied to the substrate, there is a problem that the layer between the metal foil film and the base material at the bent portion or corner portion immediately peels off and is not practical.

  In the method of manufacturing a three-dimensional circuit board according to (2) above, even if it is an effective method in the case of a flat surface, in the case of a three-dimensional substrate, the conductive metal film formed on the three-dimensional surface is irradiated with laser light. Therefore, a difference occurs in effective energy absorbed in each of the plane perpendicular to the irradiation direction of the laser beam, the inclined plane, and the parallel plane. For this reason, there has been a problem that it is difficult to uniformly remove the conductive metal film provided on the surface of the substrate, and it is difficult to form a circuit uniformly on the surface of the substrate. Also, in this manufacturing method, similarly to the manufacturing method of (1), the conductive metal film is directly formed on the surface of the base material using electroless plating. There was a problem that the adhesive strength (peel strength) was weak and impractical.

  In the method for manufacturing a three-dimensional circuit board of (3) above, a conductive circuit pattern made of a conductive paste is three-dimensionally formed on the surface of a substrate formed into a three-dimensional shape using a printing method such as screen printing, offset printing, letterpress printing, or intaglio printing. For this purpose, there is a problem that a very special and expensive equipment capable of three-dimensional drawing has to be introduced. In addition to the conductive metal powder, the conductive paste is indispensable for bonding the conductive metal powder to each other and bonding the conductive paste to the surface of the base material, but there are components such as a binder that hinders electrical conductivity and thermal conductivity. Therefore, there is a problem that the conductivity and heat dissipation are inferior to the case where the conductive circuit is formed using only a conductive metal such as a copper foil film (or plating film). In particular, it cannot be employed in a three-dimensional circuit board that requires heat dissipation.

  In addition to the above-mentioned technologies, it is also possible to attach a punching circuit prepared separately by punching a copper foil or the like to the surface of a base material formed into a three-dimensional shape, and in such a method, circuit design is possible. The degree of freedom of (design) is limited and it is not practical in terms of cost.

  Therefore, a main object of the present invention is to provide a highly reliable three-dimensional circuit board in which a base material and a conductor metal formed on the surface thereof are bonded with high peel strength. It is an object of the present invention to provide a method of manufacturing a three-dimensional circuit board that can be bonded to a metal with a high peel strength, has a high degree of freedom in circuit design, and can manufacture a three-dimensional circuit board simply and efficiently.

The invention described in claim 1 is “a base material 12 formed by molding a thermoplastic heat-resistant film having electrical insulation into a three-dimensional shape;
A conductive coating layer 14 formed by applying a conductive paste 14a to a conductive circuit forming portion on the surface of the substrate 12,
It is composed of a conductive circuit C made of a conductive plating layer 16 formed by electroplating a conductive metal on the surface of the conductive coating layer 14.
The three-dimensional circuit board 10 is characterized by the above.

  In this invention, between the base material 12 which shape | molded the heat-resistant film in the three-dimensional shape, and the conductor plating layer 16, the binder and conductor plating layer 16 (namely, high adhesive force with respect to the heat-resistant film which comprises the base material 12 (namely,). Conductive circuit C) is composed of conductive metal powder having high adhesion to the conductive metal, and formed of conductive paste 14a having high bonding strength to both substrate 12 and conductive plating layer 16. Since the conductive coating layer 14 is interposed, the base material 12 and the conductor plating layer 16 can be bonded with high peel strength.

  The invention described in claim 2 is characterized in that, in the three-dimensional circuit board 10 according to claim 1, "the heat-resistant film is an aromatic polyimide film", which is excellent in solder heat resistance (solder It is possible to easily mount an electronic component, obtain a base material 12 with high shape accuracy and light weight, and improve the heat resistance of the three-dimensional circuit board 10.

Invention of Claim 3 is the manufacturing method of the three-dimensional circuit board 10 of Claim 1 or 2, Comprising:
“Substrate molding step S1 to obtain a substrate 12 by molding a thermoplastic heat-resistant film having electrical insulation into a three-dimensional shape,
Circuit mask mounting step S2 for mounting a mask 20 formed in a three-dimensional shape in advance so as to cover the surface of the portion on the portion corresponding to the electrical insulating portion I other than the conductive circuit C provided on the surface of the base material 12,
After applying the conductive paste 14a to the conductive circuit forming portion which is the uncovered portion of the mask 20 of the base material 12, the mask 20 is removed and the conductive paste 14a is cured to obtain the conductive coating layer 14 S3 , And an electroplating process S4 in which a conductive metal is electroplated on the surface of the conductive coating layer 14 to obtain a conductive circuit C composed of the conductive plating layer 16.
This is a method for manufacturing the three-dimensional circuit board 10.

  In the present invention, first, after the heat-resistant film is formed into a three-dimensional shape to obtain the base material 12 (S1), the portion corresponding to the electrical insulating portion I of the conductive circuit C provided on the base material 12 is A mask 20 previously formed into a three-dimensional shape so as to cover the portion is mounted (S2). In this way, by using the mask 20 that has been molded in a predetermined three-dimensional shape in advance, the mask 20 can be brought into close contact with the portion corresponding to the electrical insulating portion I simply by mounting the mask 20 on the surface of the substrate 12. It is possible to mask the three-dimensional base material 12 very easily.

  Subsequently, the conductive coating layer 14 is formed by applying the conductive paste 14a to the conductive circuit forming portion of the base material 12 with the electrical insulating portion I masked, whereby screen printing, offset printing, letterpress printing, intaglio printing is performed. Compared to the case where the conductive coating layer 14 is drawn with halftone dots (dots) of the conductive paste 14a according to a predetermined pattern using a printing method such as printing, the predetermined shape is applied to the three-dimensional substrate 12 very quickly and easily. A patterned conductive coating layer 14 can be formed.

  Then, a conductive metal is electroplated on the surface of the conductive coating layer 14 to form the conductive plating layer 16 (that is, the conductive circuit C). By performing the electroplating process in this way, the conductive material is different from the electroless plating. The conductive metal can be selectively plated on the surface of the conductive coating layer 14, and the conductive metal is laminated on the surface of the conductive coating layer 14 at a higher speed and with a thicker film than in the case of using electroless plating. can do. Further, between the conductor plating layer 16 and the base material 12, a binder having a high adhesive force to the heat-resistant film constituting the base material 12 and a conductor metal constituting the conductor plating layer 16 (that is, the conductive circuit C). With a conductive coating layer 14 formed of a conductive paste 14a having a high bonding strength to both the base material 12 and the conductive plating layer 16. Therefore, the base material 12 and the conductor plating layer 16 can be joined with high peel strength.

  According to the fifth aspect of the present invention, in the method of manufacturing the three-dimensional circuit board 10 according to the fourth aspect, “After the electroplating treatment step S4, the mask 20 is mounted again on the electrical insulating portion I, and the conductive plating layer 16 is formed. Further, the surface of the conductive circuit is further subjected to a hot dip plating process, whereby it is possible to further increase the thickness of the conductive circuit C at a lower cost and to improve the conductivity and heat dissipation of the conductive circuit C. Can be further improved, the rigidity of the entire three-dimensional circuit board 10 can be improved, and further shape stability can be imparted to the three-dimensional circuit board 10.

  According to the present invention, a three-dimensional circuit board that can join a base material and a conductor metal with high peel strength, has a high degree of freedom in circuit design, and can easily and efficiently manufacture a three-dimensional circuit board. And a highly reliable three-dimensional circuit board in which the base material and the conductor metal formed on the surface thereof are joined with high peel strength.

  The present invention will be described below with reference to the drawings. A three-dimensional circuit board 10 according to an embodiment of the present invention shown in FIG. 1 is for operating electronic components such as LEDs in a three-dimensional manner. In general, the substrate 12, the conductive coating layer 14, and the conductor plating are provided. The conductive circuit C is composed of the layer 16. Here, circled circles “+” and “−” in FIG. 1 indicate a positive pole and a negative pole in the conductive circuit C, respectively.

  The base material 12 is a molded body made of a heat-resistant film having thermoplasticity and molded into a predetermined three-dimensional shape so as to maintain the form of the three-dimensional circuit board 10. In this embodiment, as shown in FIG. 1, the substrate 12 is formed in a shallow bowl shape having a stepped portion.

  Examples of the material for the heat-resistant film constituting the substrate 12 include polyimide, polyamide, polyphenylene sulfide, and liquid crystal polymer. In particular, it is preferable to use a polyimide film. Thus, by using the polyimide film excellent in heat resistance as the base material 12, it is easy to mount electronic components such as LEDs with excellent solder heat resistance, and the base material 12 with high shape accuracy can be obtained. For example, even when a power LED that emits heat of about 150 to 200 ° C. at the maximum is used as an electronic component to be mounted, there is no concern that the substrate 12 is deformed by the heat generated by the LED.

  Further, in order to obtain a molded shape of the base material 12, that is, a predetermined three-dimensional shape with high accuracy, it is preferable to use a thermoplastic aromatic polyimide film.

  Aromatic polyimide is a condensate of aromatic tetracarboxylic acid and aliphatic or aromatic diamine, typically tetracarboxylic dianhydrides such as pyromellitic dianhydride and biphenyltetracarboxylic dianhydride. And a diamine such as paraphenylenediamine and diaminodiphenyl ether to produce an amic acid, which is obtained by ring-closing curing with heat or a catalyst. The thermoplastic polyimide can be obtained, for example, by copolymerizing the following compounds.

  Examples of dicarboxylic acid anhydrides include pyromellitic dianhydride, 4,4′-oxydiphthalic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′biphenyltetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride Bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) sulfide dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3 , 4-dicarboxyphenyl) methane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) methane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) propan Anhydride, 2,2-bis (3,4-carboxyphenyl) propane dianhydride, m- phenylene bis (trimellitic acid) may be mentioned dianhydrides like.

  Examples of diamines include hexamethylenediamine, heptamethylenediamine, 3,3′-dimethylpentamethylenediamine, 3-methylhexamethylenediamine, 3-methylheptamethylenediamine, 2,5-dimethylhexamethylenediamine, octamethylenediamine, and nona. Methylenediamine, 1,1,6,6-tetramethylhexamethylenediamine, 2,2,5,5-tetramethylhexamethylenediamine, 4,4-dimethylheptamethylenediamine, decamethylenediamine, m-phenylenediamine, 4 , 4′-diaminobenzophenone, 4-aminophenyl-3-aminobenzoate, m-aminobenzoyl-p-aminoanilide, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, bis (4-aminophenyl) Nyl) methane, 1,1-bis (4-aminophenyl) ethane, 2,2-bis (4-aminophenyl) propane, 2,2′-bis [4- (4-aminophenoxy) phenyl)] propane, 4,4′-diaminodiphenyl sulfoxide, 3,3′-diaminobenzophenone, 1,3-bis (4-aminophenoxy) benzene, 2,2′-diaminozenzophenone, 1,2-bis (4-aminophenoxy) ) Benzene, 1,3-bis (4-aminobenzoyloxy) benzene, 4,4′-dibenzanilide, 4,4′-bis (4-aminophenoxy) phenyl ether, 2,2′-bis (4-aminophenyl) Hexafluoropropane, 2,2′-bis (4-aminophenyl) -1,3-dichloro-1, 1,3,3-hexafluoropropane, 4,4′- Diaminodiphenyl sulfone, 1,12-diamino-dodecane, 1,13-diamino dodecane, etc. polysiloxane diamine.

  Among the above compounds, the thermoplastic polyimide used in the present invention includes 1,3-bis (4-aminophenoxy) benzene (abbreviated as RODA), pyromellitic dianhydride (abbreviated as PMDA) and 4, Copolymer of 4′-oxydiphthalic dianhydride (ODPA), 4,4′-diaminodiphenyl ether (abbreviated as ODA) and 3,3′4,4′-biphenyltetracarboxylic dianhydride (abbreviated as BPDA) Copolymer with ODA, PMDA and BPDA, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and PMDA with 2,2′-bis [4- A copolymer with (4-aminophenoxy) phenyl)] propane (abbreviated as BAPP) is particularly preferable.

  The thermoplastic polyimide is softened by heating. In the present invention, the glass transition temperature is preferably 200 to 350 ° C., more preferably 210 to 320 ° C. from the viewpoint of solder heat resistance when mounting electronic components. More preferably, it is 250 degreeC-310 degreeC. The thermoplastic polyimide preferably has a breaking elongation at the glass transition temperature of 100 to 700%, and more preferably 150 to 400%.

  The thickness of the film formed of the material as described above and formed on the substrate 12 is preferably 12.5 to 500 μm, more preferably 25 to 300 μm, from the viewpoints of form retention and heat dissipation. Moreover, it is preferable that the thermal expansion coefficient of a film is 5-60 ppm / degrees C in the location where the wiring after shaping | molding exists.

  Examples of a method for forming the substrate 12 using such a thermoplastic heat-resistant film include a vacuum forming method and a press forming method, but the method is not particularly limited as long as it does not cause cracks or wrinkles. is not.

  The conductive coating layer 14 serves as a base of the conductor portion of the conductive circuit C provided on the surface of the base material 12, and is configured by applying a conductive paste 14a (see FIG. 3C).

  Here, as the conductive paste 14a constituting the conductive coating layer 14, a conductive metal powder such as copper, silver, tin, gold and nickel and a binder are used as main raw materials, and various additives such as a solvent and a dispersant as required. The well-known thing comprised by mix | blending can be used.

  In addition, the binder may be any of thermoplasticity, thermosetting property, or photocuring property, but it is thermosetting from the viewpoint of heat resistance and difficulty in uniform exposure due to the three-dimensional shape of the substrate 12. It is preferable to use one. However, this binder needs to have a high adhesive force to the heat-resistant film constituting the substrate 12 in any case.

  The thickness of the conductive coating layer 14 is preferably in the range of 1 to 30 μm from the viewpoints of electrical conductivity, heat dissipation or economy.

  The conductor plating layer 16 is a main conductor in the conductive circuit C, and is constituted by electroplating a surface of the conductive coating layer 14 with a simple substance or an alloy of a conductor metal such as copper, silver, solder, tin, gold and nickel. Layer. Here, when the conductive metal constituting the conductive plating layer 16 and the conductive metal powder contained in the conductive paste 14a constituting the conductive coating layer 14 are made of the same type, the adhesion between them is high. Although it is considered that the conductor plating layer 16 and the conductive coating layer 14 can be firmly bonded, even if the adhesion between the conductive metal of the conductive plating layer 16 and the conductive metal powder of the conductive coating layer 14 is poor. Separately, by providing a base layer made of a conductive metal having adhesion to both, the bond between the conductive plating layer 16 and the conductive coating layer 14 can be strengthened.

  The thickness of the conductor plating layer 16 is preferably in the range of 5 to 50 μm from the viewpoints of electrical conductivity, heat dissipation or economy.

  The pattern of the conductive circuit C composed of the conductive coating layer 14 and the conductive plating layer 16 is appropriately set according to the user's request, but the conductive circuit forming surface of the base material 12 as shown in FIG. The area ratio of the conductor on the side (conductor covering area ratio) is preferably 75% or more, more preferably 90% or more. This is because the heat diffusion efficiency on the surface of the conductor 12 and the shape holding power of the three-dimensional circuit board 10 can be improved.

  In the three-dimensional circuit board 10 shown in FIG. 1, the conductive circuit C is provided only on the upper surface (outer surface) of the base material 12. Instead, the conductive circuit C is provided only on the lower surface (inner surface). The conductive circuit C may be provided on both the inner and outer surfaces.

  Further, as in the case of the conductive circuit C, portions other than the conductive circuit forming portion of the substrate 12 may be coated with a conductive paste and then electroplated to provide a plating layer. This is because by providing such a plating layer, it is possible to further improve the heat dissipating property and the shape retention of the three-dimensional circuit board 10.

  Next, when manufacturing the three-dimensional circuit board 10 of the present invention, as shown in FIG. 2, the “base material forming step S1”, “circuit mask mounting step S2”, “conductive paste coating step S3” and “ The electroplating process S4 "is executed in this order.

  In the “base material forming step S1”, the heat-resistant film cut into a predetermined size and shape is formed into a predetermined three-dimensional shape using a vacuum forming method, a press forming method, or the like so as not to cause cracks or wrinkles. A material 12 is obtained (see FIG. 3A).

  Here, when the base material 12 is molded, it is preferable to provide the surplus portion 18 at the peripheral edge of the base material 12 as exemplified by the two-dot chain line in FIG. By providing the surplus portion 18 as described above, in the “conductive paste coating step S3” to be described later, the surplus portion 18 is provided with a conductive coat layer 14 that later becomes a positive pole of the conductive circuit C and a conductive coat layer that becomes a negative pole. 14 is formed, and in the subsequent “electroplating step S4”, the negative electrode is attached to only one portion of the connection portion, and the entire surface of the conductive coating layer 14 is attached. This is because the conductor metal can be electroplated.

  And the following "circuit mask mounting process S2" is performed for the base material 12 shape | molded by the three-dimensional shape.

  In the “circuit mask mounting step S <b> 2”, the mask 20 formed in a three-dimensional shape in advance so as to cover the surface of the portion corresponding to the electrical insulating portion I other than the conductive circuit C provided on the surface of the substrate 12. Wear it (see Fig. 3 (b)).

  Here, when the base materials 12 have a three-dimensional shape that can be superposed on each other, the mask 20 attached to the base materials 12 can be manufactured as follows. That is, one piece is extracted from the base material 12 molded into a three-dimensional shape, and the portion corresponding to the electrical insulating portion I of the extracted base material 12 is cut out to complete the production of the mask 20. According to such a method, the mask 20 can be easily produced, and the obtained mask 20 is only removed after applying the conductive paste 14a on the substrate 12, and thus the substrate 20 is removed. 12 can be used repeatedly for masking a portion to be the electrical insulating portion I on the top 12.

  Note that the mask 20 used in this step S2 is not limited to the above-described one. For example, a metal member punched into the shape of the electrical insulating portion I is bent along the surface shape of the base 12. The thing etc. may be sufficient.

  In addition, when conductive circuits are provided on both the inner and outer surfaces of the base material 12 (that is, when a double-sided circuit board is used), after forming the base material 12, drilling is performed at a predetermined position of the base material 12 by this step. preferable. If drilling is performed at such time, the conductive coating layer 14 is formed on the surface of the substrate 12 when the conductive paste is applied to the base material 12 in the subsequent “conductive paste coating step S3”. This is because a through-hole structure can be formed in the holed portion.

  In the subsequent “conductive paste coating step S3”, the conductive paste 14a was applied to the conductive circuit C forming portion of the substrate 12 (see FIG. 3C), and then the mask 20 was removed and applied onto the substrate 12. The conductive paste 14a is cured to form the conductive coat layer 14 (see FIG. 3D).

  As a coating method of the conductive paste 14a, a known coating method such as a spray method or a brush coating method can be used. Moreover, when the base material 12 and the mask 20 are firmly adhered via an adhesive material or the like, a dipping (immersion) method can also be used.

  In addition, after applying the conductive paste 14a to the conductive circuit forming portion of the substrate 12, the conductive paste 14a is cured (curing). The condition depends on the type and amount of the binder constituting the conductive paste 14a. Is set.

  And the following "electroplating process process S4" is performed for the base material 12 with which the conductive coating layer 14 was completed.

  In the “electroplating treatment step S4”, a conductor metal layer is electroplated on the surface of the conductive coating layer 14 to form the conductor plating layer 16. Here, “electroplating” means that the substrate 12 is immersed in an aqueous solution (plating solution) containing an ionized conductor metal (that is, copper, silver, solder, tin, gold, nickel, etc.), and the conductive coating layer 14 Is a method in which a conductive metal is selectively deposited on the surface of the conductive coating layer 14 by energizing with a negative electrode. Needless to say, an appropriate pretreatment such as degreasing and washing is performed prior to the “electroplating treatment step S4”.

  Then, the three-dimensional circuit board 10 is completed by forming a conductor plating layer 16 having a predetermined thickness on the surface of the conductive coating layer 14 by electroplating (see FIG. 3E).

  Note that, as described in the “base material forming step S1”, when the surplus portion 18 is provided on the outer peripheral edge portion of the base material 12 (see FIG. 1), the surplus portion 18 in the surplus portion cutting step S5. The three-dimensional circuit board 10 is completed by cutting away (FIG. 2).

  According to the manufacturing method of the three-dimensional circuit board 10 of the present embodiment, first, the heat-resistant film is formed into a three-dimensional shape to obtain the base material 12 (S1), and then the conductive circuit C provided on the base material 12 is obtained. A mask 20 formed in a three-dimensional shape in advance so as to cover the portion is attached to the portion corresponding to the electrical insulating portion I (S2). In this way, by using the mask 20 that has been molded in a predetermined three-dimensional shape in advance, the mask 20 can be brought into close contact with the portion corresponding to the electrical insulating portion I simply by mounting the mask 20 on the surface of the substrate 12. It is possible to mask the three-dimensional base material 12 very easily.

  Subsequently, the conductive coating layer 14 is formed by applying the conductive paste 14a to the conductive circuit forming portion of the base material 12 with the electrical insulating portion I masked, whereby screen printing, offset printing, letterpress printing, intaglio printing is performed. Compared to the case where the conductive coating layer 14 is drawn with halftone dots (dots) of the conductive paste 14a according to a predetermined pattern using a printing method such as printing, the predetermined shape is applied to the three-dimensional substrate 12 very quickly and easily. A patterned conductive coating layer 14 can be formed.

  Then, a conductive metal is electroplated on the surface of the conductive coating layer 14 to form the conductive plating layer 16 (that is, the conductive circuit C). By performing the electroplating process in this way, the conductive material is different from the electroless plating. The conductive metal can be selectively plated on the surface of the conductive coating layer 14, and the conductive metal is laminated on the surface of the conductive coating layer 14 at a higher speed and with a thicker film than in the case of using electroless plating. can do. Further, between the conductor plating layer 16 and the base material 12, a binder having a high adhesive force to the heat-resistant film constituting the base material 12 and a conductor metal constituting the conductor plating layer 16 (that is, the conductive circuit C). With a conductive coating layer 14 formed of a conductive paste 14a having a high bonding strength to both the base material 12 and the conductive plating layer 16. Therefore, the base material 12 and the conductor plating layer 16 can be joined with high peel strength.

  Therefore, the three-dimensional circuit board 10 manufactured by such a method has a high reliability in which the base 12 and the conductor plating layer 16 (conductor metal) are bonded with high peel strength.

  In the above-described embodiment, the three-dimensional circuit board 10 is completed at the stage where the conductor plating layer 16 is formed by electroplating (that is, the electroplating process step S4). The mask 20 may be attached to the electrical insulating portion I of the circuit C again, and the surface of the conductor plating layer 16 may be subjected to a hot dipping process with a conductive metal such as molten solder or hot zinc.

  Here, the “hot-plating treatment” refers to immersing the base material 12 on which the conductive plating layer 16 is formed in a plating bath in which a low melting point conductive metal is dissolved, or on the base material 12 on which the conductive plating layer 16 is formed. In this method, the surface of the conductive plating layer 16 is further plated with a conductive metal by pouring a plating solution in which a low melting point conductive metal is dissolved. By performing such a hot dipping process, it is possible to further increase the thickness of the conductor portion of the conductive circuit C at a lower cost, and to further improve the conductivity and heat dissipation of the conductive circuit C. In addition, the rigidity of the entire three-dimensional circuit board 10 can be improved, and further shape stability can be imparted to the three-dimensional circuit board 10. In addition, by using a high heat-resistant material such as aromatic polyimide as the base material 12, such a hot dipping process can be performed.

It is a perspective view which shows the three-dimensional circuit board of one Example of this invention. It is a flowchart which shows the manufacturing method of the three-dimensional circuit board of one Example of this invention. It is explanatory drawing which shows the manufacturing method of the three-dimensional circuit board of one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... 3D circuit board 12 ... Base material 14 ... Conductive coating layer 14a ... Conductive paste 16 ... Conductor plating layer 18 ... Excess part 20 ... Mask C ... Conductive circuit I ... Electrical insulation part

Claims (4)

A base material obtained by molding a thermoplastic heat-resistant film having electrical insulation into a three-dimensional shape;
A conductive coating layer formed by applying a conductive paste to a conductive circuit forming portion on the surface of the substrate;
A three-dimensional circuit board comprising: a conductive circuit comprising a conductive plating layer formed by electroplating a conductive metal on a surface of the conductive coating layer.   The three-dimensional circuit board according to claim 1, wherein the heat-resistant film is an aromatic polyimide film. A base material molding step for obtaining a base material by molding a thermoplastic heat-resistant film having electrical insulation into a three-dimensional shape;
A circuit mask mounting step of mounting a mask formed in a three-dimensional shape in advance so as to cover the surface of the part on the part corresponding to the electrical insulating part other than the conductive circuit provided on the surface of the base material,
A conductive paste coating step of applying a conductive paste to a conductive circuit forming portion of a base material, which is an uncoated portion of the mask, and then removing the mask and curing the conductive paste to obtain a conductive coating layer; and A method for producing a three-dimensional circuit board, comprising: an electroplating process for obtaining a conductive circuit comprising a conductive plating layer by electroplating a conductive metal on a surface of a coat layer. 4. The three-dimensional circuit board according to claim 3, wherein after the electroplating process, the mask is attached to the electrical insulating portion again, and a conductive metal is further hot-plated on the surface of the conductor plating layer. Production method.