JP2006216869A - Composite substrate and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite wiring board which is excellent in layout efficiency, can be thinned with the high degree of freedom of design, and is excellent in connection reliability as well, and a manufacturing method of the composite wiring board which is excellent in an yield and capable of simplifying processes. <P>SOLUTION: For the composite substrate, a flexible wiring board provided with a conductor part for interlayer connection and a module wiring board provided with a land for conductor joining are joined on one surface. The joining part is constituted of a joining part by an adhesive material layer and the conductor joining part of the conductor part for the interlayer connection of the flexible wiring board, and the land for the conductor joining of the module wiring board. The manufacturing method of the composite substrate comprises a process of laminating the flexible wiring board provided with a conductor circuit, an insulating layer and the conductor for the interlayer connection exposed through the insulating layer onto the conductor circuit, and the module wiring board provided with the land for the conductor joining through the adhesive material layer, so that the conductor part for the interlayer connection, and the land for the conductor joining face each other; and a process of executing the interlayer connection by heating and press fitting. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a composite substrate and a manufacturing method thereof.

  Conventionally, various printed wiring boards of single side, double side and multilayer have been widely used in the field of industrial equipment or consumer equipment. Only one printed wiring board is rarely used for one of these electronic devices. For example, a plurality of printed wiring boards (hereinafter referred to as “module wiring boards”) are used by function. It is common. The module wiring boards are connected with various connectors. On the other hand, electronic devices are oriented toward lightness, thinness and smallness, and high-density mounting printed wiring boards representing lightness, thinness and shortness are particularly incorporated in recent video cameras and notebook computers. In these electronic devices, since it is necessary to incorporate a plurality of printed wiring boards in a small space in a compact manner, it is no longer difficult to connect the boards using connectors.

  As a means for solving this problem, a rigid flexible wiring board in which a rigid wiring board is formed on a flexible wiring board by a build-up method has appeared. The rigid flexible wiring board is characterized by having a foldable portion. The foldable portion is formed by window processing for exposing the flexible wiring board by removing the rigid wiring board at a predetermined portion. The flexible part made of the exposed flexible wiring board realizes bendability and plays a role of electrically connecting the rigid parts made of the rigid wiring board that has not been removed during the window processing, that is, the module wiring boards. ing. Since a connector is unnecessary and it can be mounted thinly, there is an increasing need mainly for mobile phones and digital video cameras.

  Patent Document 1 describes a rigid flexible wiring board in which a rigid wiring board and a flexible wiring board are integrated by welding with a prepreg in which a glass substrate is impregnated with a resin having a melt viscosity of 10,000 to 50,000 poise and semi-cured. Has been. Patent Document 2 describes a method for manufacturing a rigid flexible wiring board in which a rigid wiring board and a flexible wiring board are integrated using an adhesive sheet.

  However, in the above rigid flexible wiring board, a portion of the rigid wiring board is sandwiched between one flexible wiring board and bonded with an adhesive such as a prepreg, or the flexible wiring board is sandwiched between rigid boards to be a curved portion. This is obtained by providing a window space on the rigid board, and since the at least three wiring boards are laminated, the thickness of the wiring board cannot be further reduced, and the shape and size of the board to be combined with each other are also reduced. In other words, the other depends on one of the rigid wiring board and the flexible wiring board, and there are disadvantages such as imposition efficiency, yield due to disposal of unnecessary portions, and low degree of freedom in design.

  In view of the problems of the rigid flexible wiring board as described above, it is possible to manufacture a module wiring board unit and connect the two module wiring boards with a flexible wiring board in the final process. In the case of using the conventional anisotropically conductive film or microbonding using silver paste for the connection method of the module wiring board, in the microjoining using the anisotropically conductive film, the metal-coated particles are terminals. The contact area is limited because the contact is made between them, and there is a problem that sufficient conductivity and connection reliability cannot be secured. In addition, since the silver paste is patterned by a printing method in the micro bonding using the silver paste, there is a problem that when the distance between the terminals is narrowed, the silver paste in the adjacent bonding portion is connected and a short circuit occurs. .

JP-A-7-176836 Japanese Patent Application Laid-Open No. 5-90756

  The present invention provides a composite wiring board that is excellent in imposition efficiency, has a high degree of design freedom, can be thinned, and has excellent connection reliability. Moreover, this invention provides the manufacturing method of the composite wiring board which is excellent in a yield and can simplify a process.

That is, the present invention is achieved by the following composite substrates of items 1 to 17 and the composite substrates of items 12 to 17.
1. A flexible wiring board having a conductor part for interlayer connection and a module wiring board having a conductor joining land are bonded on one side, wherein the joining part is a joint part by an adhesive layer, and the flexible wiring board A composite substrate comprising: an interlayer connection conductor portion and a conductor junction portion between a conductor junction land of the module wiring board.
2. 2. The composite substrate according to claim 1, wherein the conductor joint portion is obtained by metal joining the interlayer connection conductor portion of the flexible wiring board and the conductor joining land of the module wiring board.
3. The flexible wiring board has a conductor circuit, an insulating layer, an interlayer connecting conductor portion exposed through the insulating layer on the conductor circuit, and a conductor connecting metal layer formed in the interlayer connecting conductor exposed portion. The composite substrate according to Item 1 or 2, wherein the composite substrate is one.
4). 4. The composite substrate according to item 3, wherein the conductor connecting metal layer is made of solder.
5. 5. The composite substrate according to item 3 or item 4, wherein the flexible wiring board has an adhesive layer in the exposed conductor for interlayer connection.
6). The composite substrate according to any one of claims 1 to 5, wherein the adhesive layer is made of an adhesive having a flux function.
7. The composite substrate according to any one of Items 1 to 6, wherein the flexible wiring board and the module substrate have a conductor circuit in an outermost layer.
8). The composite substrate according to any one of Items 3 to 7, wherein the conductor circuit is formed by a semi-additive method using photolithography.
9. 9. The composite substrate according to any one of claims 1 to 8, wherein the composite substrate has a structure in which two module wiring boards are coupled by the flexible wiring board.
10. The composite substrate according to any one of Items 1 to 9, wherein the composite substrate is an electronic component mounted on the flexible wiring board.
11. The composite substrate according to any one of Items 1 to 10, wherein a plurality of the flexible wiring boards are connected.
12 A method for manufacturing a composite substrate in which a flexible wiring board and a module wiring board are bonded on one side, wherein a conductor circuit, an insulating layer, and a conductor part for interlayer connection exposed through the insulating layer on the conductor circuit A flexible wiring board having
A step of laminating a module wiring board having a conductor bonding land with an adhesive layer so that the interlayer connecting conductor portion and the conductor bonding land face each other, heating and pressure bonding, thereby connecting the interlayer connection A method for manufacturing a composite substrate, comprising the steps of:
13. 13. The method for manufacturing a composite substrate according to item 12, wherein the flexible wiring board has a conductor connecting metal layer in an exposed conductor for interlayer connection.
14 14. The method for manufacturing a composite substrate according to item 12 or 13, wherein the conductor connecting metal layer is solder.
15. The composite according to any one of Items 12 to 14, wherein the adhesive layer is formed on an exposed conductor for interlayer connection of the flexible wiring board and / or a land for conductor bonding of the module wiring board. A method for manufacturing a substrate.
16. 16. The method for manufacturing a composite substrate according to any one of Items 12 to 15, wherein the adhesive layer is formed from an adhesive having a flux function.
17. The method for manufacturing a composite substrate according to any one of Items 12 to 16, wherein the heating is performed at a temperature equal to or higher than a melting point of the conductor-connecting metal layer.

  The present invention provides a composite wiring board that is excellent in imposition efficiency, has a high degree of design freedom, can be thinned, and has excellent connection reliability. The composite wiring board of the present invention can have a finely processed wiring layer. The present invention provides a method of manufacturing a composite wiring board that is excellent in yield and that can simplify the process.

  The present invention is a composite substrate in which a flexible wiring board having an interlayer connection conductor portion and a module wiring board having a conductor joining land are joined on one side, wherein the joining portion includes an adhesive layer and the flexible wiring. It is a composite substrate characterized in that it is composed of an inter-layer connection conductor portion of a board and a conductor joint portion between conductor lands of the module wiring board. As a result, it is possible to provide a composite substrate that is excellent in imposition efficiency, has a high degree of design freedom, can be thinned, and has excellent connection reliability.

  The flexible wiring board used in the present invention may be any one that can be bent and has a solder joint (solder bump) on one surface for conductor joining with the module wiring board. As such a flexible wiring board, a single-layer or multilayer flexible circuit board having an insulating layer of polyimide resin or liquid crystal polymer resin can be used, and electronic components such as semiconductor chips and capacitors are mounted on the surface and inner layer. You may do it. Further, the flexible wiring board may be one in which a conductor circuit on the surface of the wiring board is protected by a surface protective film. As said surface protective film, what is used as protective films, such as a polyimide resin and a liquid crystal polymer resin, can be used. Examples of the method for forming the surface protective layer include a method of laminating and pressing the surface protective layer coated with an adhesive on the surface of the flexible wiring board.

  The flexible wiring board of the present invention can be manufactured by various methods, and a typical manufacturing method will be described below, but the present invention is not limited at all.

  First, a plating resist layer 102 in which a conductor circuit is patterned is formed on a metal plate 101 (FIG. 1A). Examples of the material of the metal plate 101 include copper, a copper alloy, nickel, and the like. These metal plates may be a thin metal foil. In particular, the copper foil, the copper plate, and the copper alloy plate are preferable for use as the metal plate 101 because not only electrolytic plated products and rolled products can be selected but also various thicknesses can be easily obtained.

  As a method for forming the plating resist layer 102, a conductive circuit pattern is formed by laminating an ultraviolet-sensitive dry film resist on the metal plate 101 in advance, selectively exposing using a negative film or the like, and then developing. A method of laminating the formed ones, and a resist layer is formed by applying a liquid resist with a curtain coater or a roll coater at a position where the plating resist 102 is formed on the metal plate 101, and this is exposed and developed in the same manner as described above. The method of patterning a conductor circuit by performing can be mentioned.

  Next, using the metal plate 101 as an electrolytic plating lead (power supply electrode), a resist metal layer 103 is formed by electrolytic plating on a circuit pattern portion where the plating resist layer 102 is not formed (FIG. 1B). Examples of the material of the resist metal layer 103 include nickel, gold, tin, silver, solder, palladium, and the like. The purpose of forming the resist metal layer 103 is to prevent the conductive circuit 104 shown in FIG. 1C from being etched by the chemical solution used when the metal plate 101 is etched. For example, when the material of the metal plate 101 is copper and the material of the conductor circuit 104 is copper, the material of the resist metal layer 103 is most preferably gold.

  Next, using the metal plate 101 as an electroplating lead (feeding electrode), a conductor circuit 104 is formed by electrolytic plating on the resist metal layer 102 obtained above in a circuit pattern portion where the plating resist layer 102 is not formed. Is formed (FIG. 1C). Examples of the material of the conductor circuit 104 include copper, nickel, gold, tin, silver, and palladium.

  Next, the plating resist layer 102 is removed (FIG. 1 (d)), and then an interlayer adhesive layer 106 of a flexible wiring board is formed on the conductive circuit 104 formed as described above so as to embed the insulating layer. The layer 105 is bonded by the interlayer adhesive layer 106 (FIG. 1E). As the material for the insulating layer 105 and the interlayer adhesive layer 106, any material can be used as long as it can be bent and has heat resistance capable of withstanding heating during solder bonding. Specific examples include those composed of polyimide, polyetheretherketone, polyphenylene ether, polysulfone, fluororesin, and modified products thereof. As long as the said insulating layer has adhesiveness, an insulating layer and an interlayer adhesive layer may be the same.

  Next, vias 107 are drilled in positions where conductor posts of the insulating layer 105 and the interlayer adhesive layer 106 are to be formed (FIG. 1 (f)). Examples of the method for drilling the via 107 include dry etching by laser and chemical etching by exposure / development. Laser drilling is advantageous because it does not require the insulating layer 105 to be photosensitive.

  Next, the metal plate 101 is used as an electroplating lead (power supply electrode), and the portion of the insulating layer 105 where the via 107 is formed is filled by electroplating to form a conductor post 108 (FIG. 1G). ). The conductor post 108 penetrates the insulating layer 105 and the interlayer adhesive layer 106 and joins the conductor circuit 104 and the conductor circuit of another layer in the flexible wiring board or the conductor bonding land of the module wiring board. It is a conductor part for interlayer connection. Examples of the material of the conductor post 108 include copper, nickel, gold, tin, silver, palladium, and the like, and one or more of these can be used.

Next, a solder layer 109 is formed on the tip surface where the conductor post 108 formed as described above is exposed (FIG. 1H). As the material of the solder layer 109, in addition to tin-lead solder, so-called lead-free solder such as tin-silver solder or tin-silver-copper solder may be used, and the solder layer 109 composed of a plurality of solder layers is formed. May be. For the solder layer 109, a film obtained by plating, a solder ball, or the like may be used.
In the present invention, by forming a solder layer as the conductor connecting metal layer, an alloy is formed at the conductor connecting portion between the interlayer connecting conductor portion of the flexible wiring board and the conductor connecting land of the module wiring board, Since a stronger joint can be formed, a conductor joint excellent in connection reliability can be obtained, which is more preferable. Examples of a method for forming the solder layer 109 include a method in which the metal plate 101 is formed by electrolytic plating using an electrolytic plating lead (power feeding electrode), and a method in which a paste containing a solder component is printed. In the printing method, it is necessary to accurately align the printing mask with respect to the conductor post 108. However, in the method using electrolytic plating, the solder layer 109 can be selectively formed on the surface of the conductor post 108. It is advantageous.

Next, an adhesive layer 110 with the module wiring board is formed so as to cover the front end surface of the solder layer 109 and the insulating layer 105 (FIG. 1 (i)). As a method of forming the adhesive layer 110 with the module wiring board, depending on the characteristics of the resin used, a method of directly applying an adhesive by a method such as curtain coating or bar coating, or laminating a dry film type adhesive, A method of laminating by pressing or the like can be mentioned. The adhesive layer 110 may be formed on the entire surface of the insulating layer of the flexible wiring board, or may be formed on a part of the surface such as an adhesive surface with the module wiring board.
Here, an example is shown in which the adhesive layer with the module wiring board is formed on the flexible wiring board side, but the adhesive layer may be provided on the surface on which the conductor bonding land on the module wiring board side is formed. good.

  Next, the metal plate 101 is peeled off to obtain the flexible wiring board 111 with an adhesive layer with the module wiring board. The metal plate 101 peeling includes a method of chemically etching using a chemical solution that dissolves the metal plate 101. Here, by using a chemical solution that does not dissolve the resist metal layer 103 provided between the metal plate 101 and the conductor circuit 104, the resist metal layer functions as an etching protective layer.

  Moreover, a multilayer flexible wiring board can be obtained by laminating | stacking 2 or more of the flexible wiring boards 111 with an adhesive layer obtained above. The flexible wiring board may be provided with an external connection terminal for mounting an electronic component and mounting an electronic component such as a semiconductor chip or a capacitor.

  Although the example of the formation method by the semiadditive method using photolithography was shown as a manufacturing method of the conductor circuit in the said flexible wiring board, a printing sintering method, a subtractive method, etc. are mentioned as this other method. Compared with other methods, the semi-additive method can solve problems such as circuit thinning and side etching at the time of etching, thereby enabling fine wiring processing. Further, according to this method, a conductor circuit is formed on a metal plate by electrolytic plating, an insulating resin layer composed of an interlayer adhesive layer and an insulating layer is bonded onto the conductor circuit, and then the metal plate is removed. In this way, a method of obtaining a flexible wiring board having a conductor circuit embedded in the insulating resin layer so that the exposed surface of the conductor circuit is flush with the surface of the insulating resin layer can also be adopted. Even when a fine conductor circuit having a line width of less than 20 μm is formed, the periphery of the conductor circuit is protected by the insulating resin layer, which is preferable because disconnection of the conductor circuit during the manufacturing process can be reduced. .

  In the present invention, the adhesive constituting the adhesive layer 110 with the module wiring board formed on the flexible wiring board 111 preferably has a flux function. As a specific example, a compound having a flux action and And a curable resin having an adhesive action. The adhesive having the flux function is a reducing agent for the oxide film formed on the metal layer for conductor connection, particularly the solder, and the metal surface of the conductor part for interlayer connection and the land for conductor connection, at the solder bonding temperature. Since it has the action of decomposing and removing this, and the action of causing a curing reaction at a specific temperature, it is possible to obtain a joint with excellent metal bonding and adhesion, and to obtain a joint with excellent connection reliability. preferable. Examples of the compound having a flux action include a compound having a phenolic hydroxyl group and a compound having a carboxyl group, and specific examples thereof include phenolphthaline and dihydroxybenzoic acid. As the curable resin having an adhesive action, a resin having good heat resistance and insulation, such as an epoxy resin, a cyanate resin, an isocyanate resin, a phenol resin, a polyimide resin, and a polyamideimide resin, can be used. The adhesive having the flux function is obtained by mixing the above components, but may contain other components such as a curing accelerator, a silane coupling agent, an inorganic filler, and a leveling agent as necessary.

  The module wiring board used in the present invention has a conductor bonding land which is conductively bonded to the interlayer connection conductor portion of the flexible wiring board on at least one surface. Even if it is a rigid wiring board, the flexible wiring board It may be.

Further, an example of the module wiring board will be described with reference to FIG.
As the module wiring board 201 used in the present invention, a portion to be joined (conductor joining land) 202 composed of a metal conductor layer, which is the conductor joining land, is provided on the surface and used. Any material can be applied as long as it can withstand the heating during solder connection. For example, glass substrate epoxy resin circuit boards, paper substrate phenol resin circuit boards, ceramic circuit boards, polyester circuit boards, flexible circuit boards having an insulator layer composed of polyimide resin, liquid crystal polymer resin, etc., and build-up layers A multi-layer rigid wiring board or the like formed can be used.
The module wiring board 201 may be provided with external connection terminals for mounting electronic components on the surface and inner layer thereof, and may be mounted with electronic components such as semiconductor chips and capacitors. Note that a solder resist may be formed on the surface of the module wiring board 201.
A conductor circuit layer composed of a plurality of metal layers may be used for the bonded portion 202 on the surface of the module wiring board 201. For example, a metal layer such as gold or solder may be formed on the surface for the purpose of improving the solder wettability on the surface of the conductor circuit. By doing in this way, an alloy joint part with higher intensity | strength can be formed and it can be set as a thing with high connection reliability.

  According to the present invention, when designing a module wiring board, an electronic device can be manufactured by combining a plurality of types of module wiring boards having different functions, and in that case, the types of module wiring boards to be combined are: Since it can be freely selected, the degree of freedom in design is improved.

  The composite substrate of the present invention is obtained by joining the flexible wiring board and the module wiring board on one side, and an example of the manufacturing method will be described.

  First, the conductor post 108 of the flexible wiring board 111 obtained above and the joined portion (conductor joining land) 202 of the module wiring board 201 are aligned so as to face each other (FIG. 2A) and overlapped. Place on the pressure device. As a positioning method, a method of reading a positioning mark formed in advance on the flexible wiring board 111 and the module wiring board 201 with an image recognition device, a positioning method using a positioning pin, or the like is used. be able to.

  Subsequently, the flexible wiring board 111 and the module wiring board 201 superposed on each other are heated and pressurized to melt the solder layer 109 provided on the conductor post 108 of the flexible wiring board 111, so that the flexible wiring board 111 and the module The bonding surface with the wiring board 201 is adhered, and the conductor post and the conductor bonding land are metal-bonded to form a conductor bonding portion to perform interlayer connection (FIG. 2B). In this interlayer connection method, for example, using a vacuum press, the solder layer 109 excludes the adhesive layer 110 with a flux function, and the module wiring board to-be-bonded (conductor connection land) 202 and the conductor There is a method of joining the flexible wiring board 111 and the module wiring board 201 by heating and pressurizing the post 108 until they are metal-bonded by the solder layer 109 to form a conductor joint and bonding them. Furthermore, the adhesive strength can be further improved by heating to cure the adhesive layer 110 with a flux function. It is essential that the maximum temperature during heating is equal to or higher than the melting point of the solder layer 109.

  The composite substrate 301 in which the module wiring board 201 and the flexible wiring board 111 of the present invention are joined on one side is manufactured by the steps shown in FIGS. 2A to 2B described in detail so far. be able to. FIG. 2 shows an example in which two module wiring boards and one flexible wiring board are joined on one side, but a plurality of module wiring boards are further joined on one side with a plurality of flexible wiring boards by the same method as described above. A composite substrate can be obtained. At this time, the shape of each wiring board is not limited as long as the interlayer connecting conductor portion of the flexible wiring board and the conductor joining land portion of the module wiring board can be joined.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

  In order to confirm the usefulness of the wiring board manufactured by the method for manufacturing a wiring board of the present invention, a temperature cycle test, observation of a cross section of a metal joint, and a metal junction conduction resistance test were performed.

<Preparation of adhesive varnish with flux function>
As a resin having a phenolic hydroxyl group, 106 g of phenol novolak resin (PR-53647 manufactured by Sumitomo Durez Co., Ltd., OH equivalent 106) and as a resin acting as a curing agent, diallyl bisphenol A type epoxy resin (Nippon Kayaku Co., Ltd.) ) RE-810NM, epoxy equivalent 220) 35 g, and 210 g of dicyclopentadiene type novolac epoxy resin (Nippon Kayaku Co., Ltd. XD-1000L, epoxy equivalent 250) are dissolved in 100 g of methyl ethyl ketone, and an adhesive with a flux function A varnish was prepared.

<Fabrication of flexible wiring board 111>
A dry film resist (Tokyo Ohka Kogyo AR320) is roll-laminated on a rolled copper plate copper foil (metal foil 101, Furukawa Electric EFTEC-64T, thickness 150 μm) whose surface is roughened, and exposed using a predetermined negative film. Development was performed to form a plating resist (plating resist 102) necessary for forming a conductor circuit (conductor circuit 104). Subsequently, using a rolled copper plate as a lead for electrolytic plating, gold (resist metal layer 103) was formed by electrolytic plating, and further, a conductive circuit was formed by electrolytic copper plating. The conductor circuit had a line width / interline / thickness = 40 μm / 40 μm / 10 μm. Next, a two-layer material obtained by applying an interlayer adhesive layer (interlayer adhesive layer 106, made by Sumitomo Bakelite, APL) to 25 μm thick polyimide (flexible base material 105, made by Toray, DuPont, Kapton H) by vacuum lamination, An insulator layer made of polyimide and an interlayer adhesive layer was formed by molding while embedding the irregularities of the conductor circuit.

Next, a 45 μm diameter via (via 107) is formed on an insulator layer made of polyimide and an interlayer adhesive layer by a UV-YAG laser, and the processing residue inside and around the via is subjected to wet desmear treatment using ultrasonic waves in combination. Washed off. Subsequently, the via was filled with copper by electrolytic copper plating using the rolled copper plate as a lead for electrolytic plating, thereby forming a copper post (conductor post 108). At this time, plating was performed while controlling the plating current density to 4 A / dm ² so that the tip of the copper post filled with the via became convex. Further, plating was performed until the convex tip portion protruded 5 μm from the surface of the insulator layer. Next, Sn—Ag eutectic solder (solder layer 109) was formed on the copper post to have a thickness of 5 μm by electrolytic plating using the rolled copper plate as a lead for electrolytic plating. Since the tip portion of the copper post is convex, the Sn-Ag eutectic solder surface is also convex. Next, the activator varnish with flux function obtained above is applied by bar coating to the surface of the insulating layer, that is, the surface on which the Sn—Ag eutectic solder is formed, and then dried at 80 ° C. for 20 minutes, and the thickness is 10 μm. An adhesive layer with a flux function (adhesive layer 110 with a flux function) was formed. Finally, the copper plate was removed by etching using a cupric chloride solution to obtain a flexible wiring board (flexible wiring board 111).

  Then, the joining method between said flexible wiring board and a module wiring board (module wiring board 201) is demonstrated in detail.

  First, image recognition is performed on the positioning marks previously attached to both the module wiring board (201) and the flexible wiring board (111) having pads (bonded portions 202) formed by electroless Ni / Au plating at predetermined positions. Read by the device, align and superimpose each. In this state, the temperature was raised to 250 ° C. for 45 minutes at a pressure of 1 MPa by a vacuum press, then heated and pressurized at 250 ° C. for 30 minutes, and then cooled to room temperature in 55 minutes. The metal layers were bonded to each other by Sn-Ag eutectic solder formed in the above, and the layers were bonded by an adhesive layer with a flux function. Thus, a composite wiring board (wiring board 301) in which the flexible wiring board and the module wiring board were joined was obtained.

  The obtained composite wiring board (wiring board 301) is designed so that the junction points between the 480 flexible wiring boards and the module wiring board are connected in series for the temperature cycle test. Using this composite wiring board, a temperature cycle test and cross-section observation of the joint were performed. The evaluation method and evaluation results are described below.

<Temperature cycle test>
After confirming the initial continuity of the composite wiring board obtained above, a temperature cycle test was performed with one cycle of -55 ° C for 30 minutes and 150 ° C for 30 minutes. Among the 10 composite wiring boards that were input, there was no disconnection failure after 1000 cycles of the temperature cycle test.

<Cross section observation>
When the cross section of the metal joint portion of the composite wiring board obtained above was observed with an electron microscope (SEM) and the metal joint state was evaluated, the alloy layer was not deteriorated after 1000 cycles.

  As can be seen from the above evaluation results, the composite wiring board of the present invention had no disconnection failure or deterioration of the bonded alloy layer in the temperature cycle test.

  According to the present invention, it is possible to provide a composite wiring board that is excellent in imposition efficiency, has a high degree of design freedom, can be thinned, and has excellent connection reliability. Therefore, various industrial equipment and consumer equipment can be provided. Can be used for

It is sectional drawing for demonstrating the method to manufacture an example of the flexible wiring board used for this invention. It is sectional drawing for demonstrating an example of the method of manufacturing the composite substrate of this invention.

Explanation of symbols

101 Metal Plate 102 Plating Resist Layer 103 Resist Metal Layer 104 Conductor Circuit 105 Insulating Layer 106 Interlayer Adhesive Layer 107 Via 108 Conductor Post 109 Solder Layer 110 Adhesive Layer 111 with Module Wiring Board Flexible Wiring Board with Adhesive Layer 201 Module Wiring Plate 202 To-be-joined part (conductor joining land)
301 Composite board

Claims (17)

A flexible wiring board having a conductor part for interlayer connection and a module wiring board having a conductor joining land are bonded on one side, wherein the joining part is a joint part by an adhesive layer, and the flexible wiring board A composite substrate comprising: an interlayer connection conductor portion and a conductor junction portion between a conductor junction land of the module wiring board. The composite substrate according to claim 1, wherein the conductor joint portion is obtained by metal-joining an interlayer connection conductor portion of the flexible wiring board and a conductor joining land of the module wiring board. The flexible wiring board has a conductor circuit, an insulating layer, an interlayer connecting conductor portion exposed through the insulating layer on the conductor circuit, and a conductor connecting metal layer formed in the interlayer connecting conductor exposed portion. The composite substrate according to claim 1, wherein the composite substrate is one. The composite substrate according to claim 3, wherein the conductor connecting metal layer is made of solder. The composite substrate according to claim 3 or 4, wherein the flexible wiring board has an adhesive layer in the exposed conductor for interlayer connection. The composite substrate according to claim 1, wherein the adhesive layer is composed of an adhesive having a flux function. The composite substrate according to claim 1, wherein the flexible wiring board and the module substrate have a conductor circuit in an outermost layer. The composite substrate according to claim 3, wherein the conductor circuit is formed by a semi-additive method using photolithography. The composite substrate according to any one of claims 1 to 8, wherein the composite substrate has a structure in which two module wiring boards are coupled by the flexible wiring board. The composite substrate according to claim 1, wherein an electronic component is mounted on the flexible wiring board. The composite substrate according to claim 1, wherein a plurality of the flexible wiring boards are connected. A method for manufacturing a composite substrate in which a flexible wiring board and a module wiring board are bonded on one side, wherein a conductor circuit, an insulating layer, and a conductor part for interlayer connection exposed through the insulating layer on the conductor circuit A flexible wiring board having
A step of laminating a module wiring board having a conductor bonding land with an adhesive layer so that the interlayer connecting conductor portion and the conductor bonding land face each other, heating and pressure bonding, thereby connecting the interlayer connection A method for manufacturing a composite substrate, comprising the steps of: The method of manufacturing a composite substrate according to claim 12, wherein the flexible wiring board has a metal layer for conductor connection in an exposed conductor for interlayer connection. The method for manufacturing a composite substrate according to claim 12 or 13, wherein the conductor connecting metal layer is solder. The composite substrate according to claim 12, wherein the adhesive layer is formed on an exposed conductor for interlayer connection of the flexible wiring board and / or a land for conductor bonding of the module wiring board. Production method. The method for manufacturing a composite substrate according to claim 12, wherein the adhesive layer is formed of an adhesive having a flux function. The method of manufacturing a composite substrate according to claim 12, wherein the heating is performed at a temperature equal to or higher than a melting point of the conductor connecting metal layer.

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