JP2013239565A - Flexible wiring board with reinforcement plate and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible wiring board with a reinforcement plate which facilitates the mounting of a terminal insertion mounting type electronic component, and to provide a manufacturing method of the flexible wiring board with the reinforcement plate.SOLUTION: A flexible wiring board 10 with a reinforcement plate is composed of a reinforcement plate 11A and a flexible wiring board 11B which are joined to and integrated with each other. A through hole 15, at which a terminal of an electronic component is fixedly installed, is provided penetrating through the reinforcement plate 11A and the flexible wiring board 11B. On an inner wall surface of the through hole 15, a conductive resin layer 14 fixed to an inner peripheral surface of an opening 13 provided at a rigid insulator layer 12 is formed in a thickness direction of the rigid insulator layer 12. Similarly, conductive bumps 21, each of which connects a first conductor pattern 19 of the flexible wiring board 11B with a second conductor pattern 20, are formed being fixed to a flexible insulator layer 18 in a thickness direction thereof.

Description

  The present invention relates to a flexible wiring board with a reinforcing plate and a method for manufacturing the same.

  In recent years, many electronic components mounted on flexible wiring boards have become so-called surface mount types. The surface-mount type electronic component is electrically connected to circuit wiring disposed on the surface of the flexible wiring board. The semiconductor element is sealed in a package such as an SOJ (Small Outline J-Leaded), and the lead is bent in the lateral direction and is surface-mounted. Alternatively, for example, a CSP (Chip Size Package) such as a BGA (Ball Grid Array) package, a SMD (Surface Mount Device) such as a flip chip structure bare chip, and the like are mounted on a flexible wiring board through, for example, solder balls.

  On the other hand, even for a terminal insertion mounting type electronic component that is not a surface mounting type, there is still a strong demand for easy mounting on a flexible wiring board. Conventionally, passive elements such as capacitors or resistors or discrete semiconductor elements have their leads or pins mounted on a rigid wiring board by soldering to form a printed circuit board (PCB). In that case, a through hole penetrating the rigid wiring board is provided, and a terminal such as a lead or a pin is inserted into the through hole and soldered (for example, see Patent Documents 1 and 2). Hereinafter, the lead or pin is also referred to as a terminal of an electronic component.

  However, it is difficult to solder and mount the terminals on the flexible wiring board in the same manner as the rigid wiring board. In particular, it becomes impossible in the case of a flexible wiring board having excellent flexibility.

JP 7-307543 A Japanese Patent No. 3628313

  By the way, a copper (Cu) plating layer is usually formed on the inner wall surface of a through hole provided in a hard insulator layer such as a rigid wiring board by a combination of an electroless plating method and an electrolytic plating method. And the terminal of an electronic component is fixed to the Cu plating layer of the inner wall surface of a through hole with solder. Therefore, the hard insulating layer is used as a reinforcing plate to be joined and integrated into a predetermined region of the flexible wiring board on which the electronic component is mounted. Furthermore, a through-hole penetrating the reinforcing plate and the flexible wiring board is formed. And the method of fixing the terminal of an electronic component with solder to Cu plating layer formed through the said plating method on the inner wall surface can be considered.

  However, in such a method, the same process as the case of forming a flex-rigid wiring board having a flexible part and a rigid part is required, and it is difficult to reduce the manufacturing cost.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a flexible wiring board with a reinforcing plate that facilitates mounting of a terminal insertion mounting type electronic component and a method for manufacturing the same. It is another object of the present invention to enable the flexible wiring board with a reinforcing plate to be manufactured easily and at a low cost.

  In order to achieve the above object, a flexible wiring board with a reinforcing plate according to the present invention includes a flexible flexible wiring board in which a conductor pattern is disposed on a flexible insulating layer made of resin, and the flexible wiring board. A reinforcing plate made of a rigid insulating layer harder than the flexible insulating layer joined and integrated, and through holes are formed through the flexible wiring board and the reinforcing plate in a predetermined region of the conductor pattern. At least an inner wall surface of the through hole in the reinforcing plate is formed of a conductive resin layer containing a metal powder and a binder component resin.

  And the manufacturing method of the flexible wiring board with a reinforcement board concerning this invention has the process of forming the opening hole penetrated in the thickness direction of the rigid insulator layer which consists of resin, and metal powder and resin of binder component in the said opening hole A step of filling a conductive paste comprising a conductive embedded resin layer to form a reinforcing plate, and providing a conductive pattern on a flexible insulating layer softer than the rigid insulating layer to form a flexible wiring board A step of bonding and integrating the reinforcing plate and the flexible wiring board, and the flexible wiring board and the conductive embedded resin layer from a predetermined region of the conductor pattern to the flexible wiring board and the flexible wiring board. Forming a through hole penetrating in the thickness direction of the reinforcing plate.

  Or the manufacturing method of the flexible wiring board with a reinforcement board concerning this invention includes the process of penetrating and forming the opening hole in the rigid insulator layer made of resin, and the conductive paste containing the resin of the metal powder and the binder component A step of filling the opening hole and fixing the conductive embedded resin layer to form a reinforcing plate; a step of forming a first through hole penetrating in the thickness direction of the conductive embedded resin layer; and the rigid insulator Forming a second through-hole having a diameter larger than that of the first through-hole in a flexible wiring board having a conductor pattern disposed on a flexible insulating layer softer than the first layer; and the first through-hole and the first through-hole. And a step of joining and integrating the reinforcing plate and the flexible wiring board so that the two through holes communicate with each other.

  According to the present invention, it is possible to provide a flexible wiring board with a reinforcing plate that facilitates mounting of a terminal insertion mounting type electronic component and a method for manufacturing the same. And this flexible wiring board with a reinforcement board can be manufactured simply and at low cost.

The principal part expanded sectional view which shows an example of the flexible wiring board concerning the 1st Embodiment of this invention. Sectional drawing according to a partial manufacturing process which shows an example of the manufacturing method of the reinforcement board in the 1st Embodiment of this invention. Sectional drawing according to manufacturing process which shows an example of the manufacturing method of the flexible wiring board in the 1st Embodiment of this invention. FIG. 4 is a partially enlarged plan view for explaining one step of FIG. 3. Sectional drawing according to manufacturing process which shows an example of the manufacturing method of the flexible wiring board concerning the 1st Embodiment of this invention. Sectional drawing according to a partial manufacturing process which shows the other example of the manufacturing method of the reinforcement board in the 1st Embodiment of this invention. The principal part expanded sectional view which shows the state by which the electronic component was mounted | worn with the flexible wiring board concerning the 1st Embodiment of this invention. The principal part expanded sectional view which shows an example of the flexible wiring board concerning the 2nd Embodiment of this invention. Sectional drawing according to a partial manufacturing process which shows an example of the manufacturing method of the reinforcement board in the 2nd Embodiment of this invention. Sectional drawing according to manufacturing process which shows an example of the manufacturing method of the flexible wiring board concerning the 2nd Embodiment of this invention. The principal part expanded sectional view which shows the state by which the electronic component was mounted | worn with the flexible wiring board concerning the 2nd Embodiment of this invention. The principal part expanded sectional view which shows the modification of the flexible wiring board in the 2nd Embodiment of this invention.

  Several preferred embodiments of the present invention will be described below with reference to the drawings. Here, the drawings are schematic, and ratios of dimensions and the like are different from actual ones. In these drawings, the same or similar parts are denoted by the same reference numerals, and a duplicate description is partially omitted.

(First embodiment)
A first embodiment of the present invention is a flexible wiring board with a reinforcing plate having a through hole into which a terminal insertion mounting type electronic component is inserted and soldered, and a method of manufacturing the same. Referring to FIGS. explain. As shown in FIG. 1, the flexible wiring board 10 with a reinforcement board consists of the reinforcement board 11A and the flexible wiring board 11B which were mutually joined and integrated. Here, the reinforcing plate 11A is attached to a predetermined region where the electronic component of the flexible wiring board 11B is mounted.

  In the reinforcing plate 11 </ b> A, an opening hole 13 is formed in a required portion of the rigid insulator layer 12. Then, a conductive resin layer 14 is formed so as to adhere to the inner peripheral surface of the opening hole 13. Thereby, the conductive resin layer 14 becomes a part of the reinforcing plate 11A. Furthermore, a through hole 15 having a diameter smaller than the diameter of the opening hole 13 is formed with the surface of the conductive resin layer 14 as an inner wall surface. A first conductor land 16 made of, for example, Cu foil is formed so as to surround the through hole 15 on one main surface that is the upper surface of the rigid insulator layer 12. Further, the second conductor land 17 is formed so as to surround the through hole 15 on the other main surface which is the lower surface of the rigid insulator layer 12. Here, the conductive resin layer 14, the first conductor land 16 and the second conductor land 17 are electrically connected.

  As shown in FIG. 1, the flexible flexible wiring board 11 </ b> B is made of a resin and has a flexible insulating layer 18 softer than the rigid insulating layer 12 as a base film. A first conductor pattern 19 is disposed on the upper surface, and a second conductor pattern 20 is disposed on the lower surface of the first conductor pattern 19 as a two-layer wiring structure. The first conductor pattern 19 and the second conductor pattern 20 are appropriately connected by conductive bumps 21 that are conductive members that penetrate the flexible insulator layer 18.

  Moreover, the cover layer film 22 and the soldering resist 23 are laminated | stacked and stuck to the surface layer of the upper surface of the flexible insulator layer 18 in this order. Here, the coverlay film 22 and the solder resist 23 cover the first conductor pattern 19. A part of the predetermined first conductor pattern 19 is exposed through the opening 24 provided in a required region of the cover lay film 22 and the solder resist 23. On the other hand, the flexible insulator layer 18 is laminated and integrated with the reinforcing plate 11A described above through an adhesive film 25 of an insulator adhered to the surface layer on the lower surface. Here, the adhesive film 25 covers the second conductor pattern 20 as a coverlay film on the lower surface of the flexible wiring board 11B.

  In the predetermined area where the electronic component on the upper surface of the flexible wiring board 11B is mounted, the above-described through hole 15 penetrates the flexible wiring board 11B. The through hole 15 has a predetermined first conductor pattern 19 exposed at the opening 24, a part of the conductive bump 21, a part of the flexible insulating layer 18, and a second conductor connected to the first conductor pattern 19. The conductive pattern 20 and the adhesive film 25 are penetrated.

  Moreover, it is preferable to form a composite layer in which nickel (Ni) and gold (Au) are laminated in this order on the inner wall of the through hole as the Ni / Au plating film 26. The plating film 26 chemically stabilizes the surface of the first conductor pattern 19 exposed at the opening 24 to prevent surface oxidation or the like. In addition, such a plating film 26 is formed on a single layer of a noble metal such as Au, silver (Ag), palladium (Pd), platinum (Pt) or Ni metal, or a composite layer such as Ni / Ag or Ni / Pd. It may be. Note that the plating film 26 formed in the opening 24 is formed on the first conductor pattern 19 that becomes an external connection terminal of the flexible wiring board 11B, for example. Alternatively, it is formed in a region to which the SMD is connected.

  Here, in the reinforcing plate 11A, the rigid insulator layer 12 may be either a thermosetting resin or a thermoplastic resin. Examples of the hard thermosetting resin include an epoxy resin containing glass cloth, a phenol resin, an unsaturated polyester resin, a bismaleimide / triazine resin (BT resin), and a polyimide (PI) resin. The hard thermoplastic resin has a glass transition point or melting point higher than that of lead-free solder, and examples thereof include polycarbonate, liquid crystal polymer, and polyethylene naphthalate (PEN) resin. In addition, for example, an inorganic insulator such as thin hard ceramics may be used. The thickness of the rigid insulator layer 12 depends on the material of the rigid insulator layer 12 but is appropriately determined, for example, from about 100 μm to 1 mm.

  The conductive resin layer 14 includes, for example, conductive powders such as Cu, solder, tin (Sn), iron (Fe), Ag, Au, or conductive carbon, alloy powders thereof, or composite (mixed) metal powders (hereinafter referred to as “conductive powders”). , Generically referred to as metal powder). These metal powders are kneaded with the binder component of the thermosetting resin used for the rigid insulator layer 12 described above, for example, to prepare a conductive paste. As the thermosetting resin, for example, an epoxy resin, a phenol resin, or a PI resin is preferably used.

  Moreover, a thermoplastic resin can also be used as a binder component. The thermoplastic resin preferably has a glass transition point or melting point lower than that of the thermoplastic resin constituting the rigid insulator layer 12 and higher than the melting point of lead-free solder. For example, polycarbonate resin, PEN resin, polyethylene terephthalate (PET) resin, polyether ether ketone (PEEK) resin, polyphenylene sulfide (PPS) resin, and the like are used.

In the conductive resin layer 14, the electrical resistivity increases as the amount of the binder component made of the resin increases. The conductive resin layer 14 depends on the mixed metal powder, but the component of the binder so that the resistivity is, for example, in the range of about 5 × 10 ⁻⁶ Ω · cm to 10 ⁴ Ω · cm. The amount is appropriately determined and prepared. Here, if the resistivity is too low, the adhesion strength of the conductive resin layer 14 to the inner peripheral surface of the opening hole 13 formed in the rigid insulator layer 12 becomes insufficient. On the other hand, if the resistivity becomes too high, the wettability of the solder in the through hole 15 having the surface of the conductive resin layer 14 as the inner wall surface is lowered. Further, the fixing of the terminals of the electronic components inserted into the through holes 15 through solder becomes insufficient.

  The first conductor land 16 and the second conductor land 17 are formed of a metal foil such as Cu or Cu alloy attached to the surface of the rigid insulator layer 12. Alternatively, it may be made of a metal film plated on the surface of the rigid insulator layer 12. The thickness is appropriately determined, for example, from about 5 μm to 50 μm depending on the metal material.

  In the flexible wiring board 11B, the flexible insulating layer 18 may be either a thermosetting resin or a thermoplastic resin. Examples of the soft thermosetting resin include epoxy resins, polyester resins, PI resins, and composite resins such as these. The soft thermoplastic resin has a glass transition point or melting point higher than that of lead-free solder, and examples thereof include liquid crystal polymers, PET resins, PEEK resins, and PPS resins. Although the thickness of the flexible insulator layer 18 depends on the material, it is, for example, about 20 μm to 100 μm.

  The conductive bumps 21 connecting the layers of the conductor pattern disposed in the two-layer wiring structure on both surfaces of the flexible insulator layer 18 are made of metal powder such as Ag, Au, Cu, Sn, conductive carbon, and epoxy resin. It is formed from a conductive paste mixed with PI resin, phenol resin and the like. The conductive paste used for the conductive bump 21 may be the same as that used for the conductive resin layer 14 described above. In addition, in the flexible wiring board 11B, other structures are not particularly different from known ones.

  The adhesive film 25 that joins and integrates the flexible wiring board 11B and the reinforcing plate 11A is made of a thermosetting resin or a thermoplastic resin. As the thermosetting resin, a PI resin, an epoxy resin, or a thermosetting synthetic resin containing oligophenylene ether and a styrene butadiene elastomer is used. As such a synthetic resin, for example, ADFLEMA OPE system (trade name, manufactured by NAMICS) is exemplified. And the film thickness is set to about 10 micrometers-50 micrometers, for example. Here, in the case of a resin such as a PI-based resin, for example, the reinforcing plate 11A and the flexible wiring board 11B may be joined via adhesive layers formed on both surfaces thereof.

  Moreover, as a thermoplastic resin which comprises the adhesive film 25, a liquid crystal polymer, a PEN-type resin, etc. are used suitably.

  Next, an example of the manufacturing method of the flexible wiring board with the reinforcement board for electronic component mounting concerning the 1st Embodiment of this invention is demonstrated. In the manufacture of the reinforcing plate 11A, as shown in FIG. 2A, a resin rigid insulator layer 12 having a thickness of, for example, about 100 μm to 1 mm is prepared. Then, drilling of the predetermined position is performed. In this drilling, the opening hole 13 is formed by punching, drilling, laser processing or the like. Thereafter, both surfaces of the rigid insulator layer 12 and the inner wall surface of the opening hole 13 are cleaned. Here, the planar shape of the opening hole 13 is formed in various shapes such as a rectangle, a triangle, a polygon, a circle, an ellipse, and the like.

  Subsequently, as shown in FIG. 2B, the opening embedded hole 13 is filled with the conductive embedded resin layer 27 made of the conductive paste containing the metal powder and the resin as described above. The filling of the conductive embedded resin layer 27 can be easily performed by rubbing the conductive paste on the surface of the rigid insulator layer 12 using, for example, a squeegee. Alternatively, the conductive paste is poured into the opening hole 12 by a printing method or the like. Thereafter, a heat treatment at a predetermined temperature is performed to cure the resin component of the conductive paste.

  Then, mechanical polishing and desmearing are performed to flatten and clean both surfaces of the rigid insulator layer 12 and the exposed surface of the conductive embedded resin layer 27 filled in the opening holes 13.

  Next, a plated layer of about 5 μm to 50 μm is deposited on both surfaces of the rigid insulator layer 12 and the exposed surface of the conductive embedded resin layer 27 by, for example, an electroless plating method or an electrolytic plating method of Cu or Cu alloy. Then, selective etching using photolithography is performed on the plating layer. In this way, as shown in FIG. 2C, the first conductor land 16 and the second conductor land 17 having a pattern covering the conductive embedded resin layer 27 are formed.

  Then, in the manufacture of the flexible wiring board 11B, as shown in FIG. 3A, for example, a cone which is a required number of protruding conductors on the inner surface of the lower metal foil 28 made of Cu having a thickness of about 10 μm to 30 μm. A conductive paste 29 is prepared by bumping. Here, the conical conductive paste 29 is bumped by repeating screen printing and drying of the conductive paste using, for example, a stainless steel screen plate. Here, as described above, the conductive paste is a mixture of, for example, metal powder such as Ag, Au, Cu, Sn, and carbon and an epoxy resin, a phenol resin, an acrylic resin, or the like.

  Next, as shown in FIG. 3B, a resin film 30 made of, for example, a liquid crystal polymer having a thickness of about 15 μm to 50 μm and an upper metal foil 31 are laminated on the lower metal foil 28 and set up. Subsequently, the lower surface metal foil 28, the resin film 30, and the upper surface metal foil 31 are bonded by thermocompression with a hot press. Here, the resin film 30 may be the thermosetting resin described above.

In the hot press, the atmosphere gas is preferably in a reduced pressure state, for example, and the heating temperature at that time is a temperature at which the resin film 30 made of a thermoplastic liquid crystal polymer is thermally softened. In the case of a thermosetting resin, the temperature at that time is a temperature at which the resin film 30 is thermoset. For example, the temperature is set to about 180 ° C to 230 ° C. Moreover, pressurization is about 30-100 kgf / cm < ² >, for example.

  In this way, as shown in FIG. 3 (c), the conical conductive paste 29 changes its composition along with the plastic deformation in which the head is crushed to form the conductive bump 21, and the lower metal foil 28 and the upper surface The metal foil 31 is electrically connected. The resin film 30 becomes the flexible insulator layer 18. And the double-sided metal-clad laminate 32 is produced.

  Here, the conductive bump 21 formed at the position of the through hole 15 described in FIG. 1 will be described with reference to FIG. FIG. 3C is a sectional view taken along the line XX in FIG. In the double-sided metal-clad laminate 32 of FIG. 3C, a plurality of conductive bumps 21 formed at positions where the through holes 15 are formed are arranged at predetermined positions. That is, as shown in FIG. 4, for example, a plurality (eight in FIG. 4) of conductive bumps 21 are arranged along the peripheral edge 151 that is the circumference of the through hole 15 having a circular planar shape. The arrangement of the conductive bumps 21 is not limited to the circumference, and is appropriately arranged on the periphery according to the shape of the through hole 15. Note that the planar shape of the through hole 15 may be, for example, an ellipse, a rectangle, or a polygon according to the terminal of the electronic component to be inserted. The conductive bumps 21 formed in the region other than the through hole 15 as the conductive member are usually arranged one by one.

  By arranging the plurality of conductive bumps 21 at the positions where the through holes 15 are formed in this way, the conical conductive paste 29 can easily penetrate the resin film 30 in the heat press in the step of FIG. Become. Further, since the contact surface between the conductive bump 21 and the flexible insulator layer 18 is increased, the adhesion between the conductive bump 21 and the flexible insulator layer 18 is improved.

  Next, selective etching using photolithography is performed on the lower surface metal foil 28 and the upper surface metal foil 31, respectively. 3D, the upper surface metal foil 31 and the lower surface metal foil 28 are patterned into a first conductor pattern 19 and a second conductor pattern 20, respectively. Then, as shown in FIG. 3E, a cover lay film 22 made of a thermosetting resin such as a PI resin and a solder resist 23 laminated thereon are formed by a known method. Thereafter, selective etching using photolithography is performed to provide an opening 24 in the predetermined first conductor pattern 19.

  Next, as shown in FIG. 5 (a), for example, the reinforcing plate 11A in the state of FIG. 2 (c) is in the state of FIG. 3 (e) through an uncured or semi-cured adhesive film 25, for example. The flexible wiring board 11B is bonded by thermocompression. Here, the second conductor pattern 20 of the flexible wiring board 11B is covered and protected by the adhesive film 25.

  Next, as shown in FIG. 5B, through holes 15 penetrating the reinforcing plate 11A and the flexible wiring board 11B are formed by, for example, drilling. The through hole 15 penetrates the first conductor pattern 19, a part of the plurality of conductive bumps 21, a part of the flexible insulator layer 18, and the second conductor pattern 20 in the flexible wiring board 11 </ b> B. Then, it penetrates through the adhesive film 25 and penetrates the first conductive land 16, the conductive embedded resin layer 27 embedded in the opening hole 13, and the second conductive land 17 in the reinforcing plate 11 </ b> A.

  Here, the through hole 15 is bored with a diameter smaller than that of the opening hole 13. In this way, the conductive resin layer 14 firmly fixed in the thickness direction of the rigid insulator layer 12 on the inner peripheral surface of the opening hole 13 is formed on the inner wall surface of the through hole 15. Note that the planar shape of the through hole 15 is appropriately matched to the terminal of the electronic component inserted as described above.

  Next, mechanical polishing and desmear processing are performed to clean the exposed surfaces such as the first conductor pattern 19, the second conductor land 17, and the inner wall surface of the through hole 1. Then, as shown in FIG. 5C, a Ni / Au plating film 26 is formed by an electroless plating method by a so-called partial plating method using a photoresist plating mask (not shown). Here, the thickness of the plating film 26 is, for example, about 1 μm for the underlying Ni layer and about 0.2 μm for the Au layer.

  After performing the above, through the so-called outer shape processing, the flexible wiring board 10 with a reinforcing plate having a desired shape as described in FIG. 1 is manufactured. There are various modifications to the flexible wiring board 10 with a reinforcing plate and its manufacturing method. Accordingly, a modification of the reinforcing plate 11A will be described with reference to FIG. A double-sided copper clad laminate having a rigid insulator layer 12 is prepared. Then, the copper foil stuck to the upper and lower surfaces of the rigid insulator layer 12 is patterned by selective etching using photolithography. In this way, first conductor lands 16 and second conductor lands 17 are first formed as shown in FIG.

  Next, as shown in FIG. 6B, the opening hole 13 is drilled by drilling, laser processing or the like so as to penetrate the first conductor land 16, the rigid insulator layer 12, and the second conductor land 17. Set up. Thereafter, both surfaces of the rigid insulator layer 12 and the inner wall surface of the opening hole 13 are cleaned.

  Then, as shown in FIG. 6C, a conductive embedded resin layer 27 made of a conductive paste is filled in the opening hole 13 and thermally cured. This filling method is the same as that described with reference to FIG. Thereafter, mechanical polishing and desmearing are performed to flatten and clean the both surfaces of the rigid insulator layer 12 and the exposed surface of the conductive embedded resin layer 27 filled in the opening holes 13. And the flexible wiring board with a reinforcement board for electronic component mounting can be manufactured through the process similar to FIG. 5 using the reinforcement board 11A of such a structure.

  As another modified example, the reinforcing plate 11A can be applied to the flexible wiring board 10 with the reinforcing plate for mounting electronic components even if the first conductor land 16 and the second conductor land 17 are not formed. .

  Next, an example in which a terminal insertion mounting type electronic component is mounted on the flexible wiring board 10 with a reinforcing plate will be described with reference to FIG. For example, a lead 33 which is a terminal of an electronic component of DIP (Dual Inline Package) is inserted into the through hole 15 and fixed to the conductive resin layer 14 of the reinforcing plate 11A and the conductive bump 21 of the flexible wiring board 11B through the solder 34. Is done. The solder 34 is also soldered to the surface of the first conductor pattern 19 and the surface of the second conductor land 17. In this way, the electronic component is fixed in the through hole 15 of the flexible wiring board 10.

  Specifically, first, a solder paste is printed in the opening 24 on the through hole 15. Then, the lead 33 of the electronic component is inserted and placed in the through hole 15, and heat treated in a solder reflow furnace, and reflow soldered from the upper surface side of the flexible wiring board 11B. Subsequently, flow soldering is performed from the lower surface side of the reinforcing plate 11A. Here, a plurality of DIP leads 33 are inserted into the corresponding through holes 15 and fixed by solders 34 respectively.

  In this manner, the solder 34 is soldered to the surface of the first conductor pattern 19 and the surface of the second conductor land 17 to fix the lead 33 through the soldering twice. Then, a first solder fillet 35 and a second solder fillet 36 are formed at each point, and the lead 33 is firmly fixed. Note that the solder used in the solder reflow method and the flow method is the same type or different type of eutectic solder, for example.

  In the reinforcing plate 11A, the solder 34 can be firmly soldered to the metal powder exposed on the surface of the conductive resin layer 14 constituting the inner wall surface of the through hole 15. In the flexible wiring board 11 </ b> B, the solder 34 can be firmly soldered to the conductive bumps 21 constituting the inner wall surface of the through hole 15.

  The plating film 26 can stabilize the soldering of the lead 33 into the through hole 15 when the electronic component is attached to the through hole 15 of the lead 33 with the solder 34 described above. This is because solder bonding occurs with the resin component on the surface of the conductive resin layer 14 exposed in the through hole 15, the flexible insulating layer 18, or the plating film 26 attached to the inner wall surface of the adhesive film 25.

  In the flexible wiring board 10 with the reinforcing plate of the present embodiment, the solder 34 is firmly soldered to the metal powder exposed on the surface of the conductive resin layer 14 constituting the inner wall surface of the through hole 15 in the reinforcing plate 11A. be able to. Further, in the flexible wiring board 11 </ b> B, the solder 34 is firmly soldered to the conductive bumps 21 constituting the inner wall surface of the through hole 15. Here, when the plating film 26 is interposed, the solder 34 is fixed to the inner wall surface of the through hole 15 via the plating film 26.

  Alternatively, the solder 34 is soldered to the surface of the first conductor pattern 19 and the surface of the second conductor land 17. Then, a first solder fillet 35 and a second solder fillet 36 are formed at each location.

  In this way, the terminal insertion mounting type electronic component has its lead 33 inserted into the through hole 15 provided in the flexible wiring board 10 with the reinforcing plate, and is firmly and stably fixed by the solder 34. In addition, a terminal insertion mounting type electronic component such as a passive element such as a capacitor or a resistor or a discrete semiconductor element that is not a surface mounting type can be easily mounted on the flexible wiring board. Here, these electronic components are mounted on a flexible wiring board with stable and high reliability.

  Moreover, the flexible wiring board with a reinforcing plate can be manufactured easily and at low cost by the method for manufacturing a flexible wiring board with a reinforcing plate of the present embodiment.

(Second Embodiment)
Next, a flexible wiring board with a reinforcing plate for mounting electronic components according to a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, a case will be described where a terminal of an electronic component can be fixed to a through hole through one soldering. The differences from the first embodiment will be mainly described below.

  As shown in FIG. 8, the flexible wiring board 40 with a reinforcing plate includes a reinforcing board 11A and a flexible wiring board 11B that are joined and integrated with each other in the same manner as described in the first embodiment. Here, in the reinforcing plate 11 </ b> A, a first through hole 42 is formed at a required portion of the rigid insulator layer 12. In the flexible wiring board 11 </ b> B, a second through hole 42 having a diameter larger than that of the first through hole 41 is formed so as to overlap the first through hole 41. Thus, the through hole formed by communicating the first through hole 41 and the second through hole 42 has a structure in which the diameter of the flexible wiring board 11B is increased.

  It should be noted that a plurality of conductive bumps 21 are arranged along the periphery of the second through hole 42 at the position where the second through hole 42 is formed, as described in the first embodiment. Is done. However, the second conductor land is not provided on the lower surface of the rigid insulator layer 12.

  In the flexible wiring board 40 with a reinforcing plate shown in FIG. 8, other structures are substantially the same as those in the first embodiment, and detailed description thereof is omitted. However, the plating film 26 shown in the figure chemically stabilizes the surface of the first conductor pattern 19 exposed at the opening 24 and prevents its oxidation and the like, as described in the first embodiment. In some cases, it is not necessary.

  Next, an example of the manufacturing method of the flexible wiring board with a reinforcement board concerning the 2nd Embodiment of this invention is demonstrated. In the manufacture of the reinforcing plate 11A, a single-sided copper-clad laminate having a rigid insulator layer 12 is prepared. Then, by selective etching using photolithography, as shown in FIG. 9A, the copper foil stretched on the upper surface of the rigid insulator layer 12 is patterned to form the first conductor land 16. .

  Next, as shown in FIG. 9B, an opening hole 13 is formed by drilling, laser processing or the like so as to penetrate the first conductor land 16 and the rigid insulator layer 12. Thereafter, both surfaces of the rigid insulator layer 12 and the inner wall surface of the opening hole 13 are cleaned. Then, in the same manner as described in the first embodiment, as shown in FIG. 9C, a conductive embedded resin layer 27 made of a conductive paste is filled in the opening hole 13.

  Thereafter, mechanical polishing and desmearing are performed to flatten and clean the both surfaces of the rigid insulator layer 12 and the exposed surface of the conductive embedded resin layer 27 filled in the opening holes 13. Then, for example, by drilling, as shown in FIG. 9 (d), a hole is made in the conductive embedded resin layer 27 embedded in the opening hole 13, and the first through hole 41 is formed. Here, as described in the first embodiment, the first through hole 41 has a diameter smaller than that of the opening hole 13 by about 0.2 mm, for example.

  As shown in FIG. 10A, the second through hole 42 is formed in the flexible wiring board 11B by, for example, drilling. The second through hole 42 penetrates through the first conductor pattern 19, a part of the plurality of conductive bumps 21, a part of the flexible insulator layer 18, and the second conductor pattern 20 in the flexible wiring board 11 </ b> B. To do. The diameter is set larger than that of the first through hole 41. Here, the second through hole 42 has a diameter larger than that of the first through hole 41 by, for example, about 0.2 mm to 1 mm.

  Then, as shown in FIG. 10B, the adhesive film 25 in which the second through hole 42 is formed at a predetermined location by, for example, punching is attached to the upper surface of the reinforcing plate 11A. Thereafter, the reinforcing plate 11A and the flexible wiring board 11B are aligned and joined and integrated by overlapping thermocompression bonding. The adhesive film 25 becomes a coverlay film on the lower surface of the flexible wiring board 11B.

  Next, as shown in FIG.10 (c), the plating film 26 is formed by the electroless-plating method as needed. The plating film 26 is formed on the first conductor pattern 19 exposed at the opening 24 of the flexible wiring board 11B, and chemically stabilizes the surface thereof to prevent oxidation, for example. Here, the plating film 26 is also deposited on the inner wall surfaces of the first through hole 41 and the second through hole 42. Thereafter, the flexible wiring board 40 as shown in FIG.

  Next, an example in which electronic components are mounted on the flexible wiring board 40 with a reinforcing plate will be described with reference to FIG. The lead 33 of the electronic component is inserted into a through hole having a diameter-enlarged structure of the first through hole 41 and the second through hole 42, and the conductive resin layer 14 of the reinforcing plate 11A and the conductive bump of the flexible wiring board 11B. 21 is fixed through solder 34. The solder 34 is also soldered to the surface of the first conductor pattern 19 and the surface of the first conductor land 16. In this way, the electronic component is fixed to the through hole having a diameter-enlarged structure of the first through hole 41 and the second through hole 42 of the flexible wiring board 40.

  Specifically, for example, after solder paste such as cream solder is printed in the opening 24 on the second through hole 42, the lead 33 of the electronic component is transferred from the second through hole 42 to the first through hole 41. insert. By inserting the lead 33, a part of the solder paste is press-fitted together with the lead 33 to the upper part of the first conductor land 16 and the first through hole 41. Thereafter, heat treatment is performed in a solder reflow furnace.

  Here, in the terminal insertion mounting type electronic component, the plurality of leads 33 are inserted into a plurality of through holes provided corresponding to the respective leads 33. Then, through one soldering, the solder 34 forms a first solder fillet 35 at the first conductor pattern 19 and is soldered to the inner wall surface of the through hole to firmly fix the electronic component.

  In the present embodiment, when the plating film 26 is not formed, the solder 34 constitutes the inner wall surface of the first through hole 41 in the reinforcing plate 11A as described in the first embodiment. The metal powder exposed on the surface of the conductive resin layer 14 is also firmly soldered. Further, in the flexible wiring board 11 </ b> B, the solder 34 is firmly soldered to the conductive bumps 21 constituting the inner wall surface of the second through hole 42.

  When the plating film 26 is formed, the resin component on the surface of the conductive resin layer 14 exposed in the first through hole 41, the flexible insulator layer 18, or the inner wall surface of the adhesive film 25 is deposited. Solder joint with the plating film 26 to be generated occurs. Further, the solder 34 is fixed to the metal powder and the conductive bump 21 exposed on the surface of the conductive resin layer 14 through the plating film 26 to be soldered.

  Next, a modification of the flexible wiring board with a reinforcing plate according to the second embodiment will be described with reference to FIG. Also in this case, the flexible wiring board 50 with a reinforcing plate is composed of a reinforcing plate 11A and a flexible wiring board 11B which are joined and integrated with each other. Here, the reinforcing plate 11 </ b> A has the same structure as that described in the second embodiment, and has a first through hole 41. On the other hand, the flexible wiring board 11 </ b> B having a one-layer wiring structure includes the second through hole 42 but does not have the conductive bump 21. The second through hole 42 has a structure that penetrates the first conductor pattern 19, the flexible insulator layer 18, and the adhesive film 25 and has a diameter larger than that of the first through hole 41.

  As another modification, the reinforcing plate 11A may have a structure in which the second conductor land 17 described in the first embodiment is formed.

  Even in the flexible wiring board 50 with the reinforcing plate, the fixing of the terminal insertion mounting type electronic component is almost the same as that of the flexible wiring board 40. However, when the plating film 26 is not deposited, the exposed surface of the flexible insulating layer 18 is not soldered to the solder 17 on the inner wall surface of the second through hole 42. However, in the solder reflow heat treatment, the solder paste wets the surface of the first conductor land 16 and flows into the first through hole 41, and is soldered to the conductive resin layer 14 in the first through hole 41. The electronic component is firmly fixed to the first through hole 41 and the second through hole 42 by solder 34. This modification is suitable as the film thickness of the flexible insulating layer 18 of the flexible wiring board 11B having high flexibility or flexibility is reduced.

  In the second embodiment, the same effect as described in the first embodiment is obtained. In addition, since the electronic component can be fixed by one soldering, it is possible to reduce the cost of mounting the terminal insertion mounting type electronic component on the flexible wiring board. And the flexible printed circuit board by which the said electronic component is mounted in a flexible wiring board can be produced now at low cost.

  For convenience, the description has been made using the terms “upper surface” and “lower surface”. The “upper surface” and the “lower surface” mean that they are in a relationship of front and back, and do not mean spatial top and bottom.

  Although the preferred embodiments of the present invention have been described above, the above-described embodiments do not limit the present invention. Those skilled in the art can make various modifications and changes in specific embodiments without departing from the technical idea and technical scope of the present invention.

  In the above embodiment, the case where the flexible wiring board has a one-layer wiring structure or a two-layer wiring structure has been described.

  In addition, in the through hole in which the terminal of the electronic component is fixed, instead of the conductive bump connecting the wiring layers, for example, a Cu plating layer may be formed on the inner wall surface of the through hole. Good. Alternatively, a conductive paste may be filled and formed as a conductive member instead of the conductive bump.

  Moreover, in the flexible wiring board with a reinforcement board shown in 2nd Embodiment, you may make it use the double-sided metal-clad laminated board shown in 1st Embodiment in the reinforcement board 11A used.

  DESCRIPTION OF SYMBOLS 10, 40, 50 ... Flexible wiring board with a reinforcement board, 11A ... Reinforcement board, 11B ... Flexible wiring board, 12 ... Rigid insulator layer, 13 ... Opening hole, 14 ... Conductive resin layer, 15 ... Through-hole, 151 ... Peripheral edge, 16 ... first conductor land, 17 ... second conductor land, 18 ... flexible insulator layer, 19 ... first conductor pattern, 20 ... second conductor pattern, 21 ... conductive bump, 22 ... cover Lay film, 23 ... solder resist, 24 ... opening, 25 ... adhesive film, 26 ... plating film, 27 ... conductive embedded resin layer, 28 ... bottom metal foil, 29 ... conical conductive paste, 30 ... resin film, 31 ... upper surface metal foil, 32 ... double-sided metal-clad laminate, 33 ... lead, 34 ... solder, 35 ... first fillet, 36 ... second fillet, 41 ... first through hole 42 ... second through-hole

Claims (7)

A flexible flexible wiring board in which a conductor pattern is disposed on a flexible insulating layer made of resin;
A reinforcing plate made of a rigid insulator layer harder than the flexible insulator layer joined and integrated with the flexible wiring board;
A through hole is formed through the flexible wiring board and the reinforcing plate in a predetermined region of the conductor pattern, and at least an inner wall surface of the through hole in the reinforcing plate is a conductive resin layer containing a metal powder and a resin of a binder component. A flexible wiring board with a reinforcing plate, which is formed.   On the inner wall surface of the through-hole, conductive bumps containing metal powder and resin that connect between the conductive pattern layers of the flexible wiring board are fixedly formed in the thickness direction of the flexible insulator layer. The flexible wiring board with a reinforcing plate according to claim 1.   3. The flexible wiring board with a reinforcing plate according to claim 1, wherein a conductor land is formed so as to surround the through hole on one main surface of the rigid insulator layer. Forming an opening hole penetrating in the thickness direction of the rigid insulator layer made of resin;
Filling the opening hole with a conductive paste comprising a metal powder and a binder component resin to form a conductive embedded resin layer and forming a reinforcing plate;
A step of forming a flexible wiring board by disposing a conductor pattern on a flexible insulator layer that is softer than the rigid insulator layer;
A step of joining and integrating the reinforcing plate and the flexible wiring board;
Forming a through-hole penetrating in a thickness direction of the flexible wiring board and the reinforcing plate from a predetermined region of the conductor pattern in the flexible wiring board and the conductive embedded resin layer;
The manufacturing method of the flexible wiring board with a reinforcement board characterized by having. A step of forming an opening hole in a rigid insulator layer made of resin; and
Filling the opening hole with a conductive paste comprising a metal powder and a binder component resin, and fixing a conductive embedded resin layer to form a reinforcing plate;
Forming a first through hole penetrating in the thickness direction of the conductive embedded resin layer;
Forming a second through hole having a diameter larger than that of the first through hole in a flexible wiring board in which a conductor pattern is disposed on a flexible insulating layer softer than the rigid insulating layer;
A step of joining and integrating the reinforcing plate and the flexible wiring board so that the first through hole and the second through hole communicate with each other;
The manufacturing method of the flexible wiring board with a reinforcement board characterized by having.   A plurality of conductive bumps including a metal powder and a resin penetrating the flexible insulator layer and connecting the layers of the conductor pattern are formed along a peripheral edge of the inner wall surface of the through hole to form the through hole. 6. The method according to claim 4, wherein the conductive bump is formed so as to surround an inner wall surface of the through hole by being cut out in a thickness direction of the flexible insulator layer. Manufacturing method of flexible wiring board with reinforcing plate.   7. The conductor land provided on one main surface of the rigid insulator layer is formed so as to surround the through hole by being cut out in the step of forming the through hole. The manufacturing method of the flexible wiring board with a reinforcement board as described in any one of Claims.

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