JP4759381B2 - Device-embedded circuit board and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an element-incorporated circuit board which is reliable and can be made highly functional and compact, and to provide its manufacturing method. <P>SOLUTION: The element-incorporated circuit board comprises an interlayer insulation layer 1 formed of thermoplastic resin, a first interconnection circuit 2 formed on one principal plane of the interlayer insulation layer 1, and a second interconnection circuit 3 formed on the other principal plane of the interlayer insulation layer 1. The interconnection 3a of the second interconnection circuit 3 includes a convex portion 4 which penetrates through the interlayer insulation layer 1 and is exposed on the one principal plane. The interconnection 3b of the second interconnection circuit 3 includes a concave portion 5 encompassed by the interconnection insulation layer 1. On the bottom of the concave portion 5, a semiconductor chip 8 is mounted via a plating layer 6. A bonding wire 9 connects an electrode pad of the semiconductor chip 8 and the convex portion 4. A sealing resin 10 is formed on the entire surface by sealing the semiconductor chip 8 in the concave portion 5 and covering the first interconnection circuit 2. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a circuit board with a built-in element and a manufacturing method thereof, and more particularly to a circuit board with a built-in element composed of a double-sided copper-clad laminate containing electronic components composed of functional elements and a manufacturing method thereof.

  As electronic devices such as portable devices become shorter, lighter and thinner, circuit boards on which electronic components are mounted are strongly required to have higher density wiring and shorter, lighter and thinner, and various multilayer wiring boards have been developed. ing. For example, a multilayer wiring board in which a double-sided copper-clad laminate is used as an inner layer substrate and an interlayer insulator layer and a wiring pattern layer (wiring circuit) are laminated as outer layers on both sides thereof is put into practical use. Here, the double-sided copper-clad laminate is obtained by arranging copper foils on both sides of an interlayer insulator layer made of a thermosetting resin and integrating them by heating and pressing. Further, as the interlayer insulator layer, a thermosetting resin such as a glass epoxy type, a polyester resin type, a polyimide resin type or the like that normally exhibits functions such as electrical insulation between wiring circuits and mechanical support is used. . In addition, the wiring circuits of each layer of the multilayer wiring board are electrically connected by a conductor penetrating an interlayer insulating layer interposed therebetween.

  In this type of multilayer wiring board, for example, semiconductor package parts made of active elements such as transistors, diodes, and ICs, or electronic parts made of passive elements such as resistors and capacitors are usually placed on the uppermost layer of the multilayer wiring board. Surface mounted on the wiring circuit surface. Hereinafter, such an electronic component of an active element (also referred to as an active element component) and an electronic component of a passive element (also referred to as a passive element component) are collectively referred to as a functional element component.

  Furthermore, in order to increase the mounting density of functional element parts on the circuit board, a through hole is formed in a part of the interlayer insulating layer of the multilayer wiring board, and a passive element such as a resistor chip, a capacitor, and an inductance is formed in the through hole. A multilayer wiring board having a configuration in which components are accommodated has been developed (see, for example, Patent Document 1). Alternatively, a recess or a cavity is provided in a part of the interlayer insulator layer of the multilayer wiring board, and a multilayer in which an active element component such as a semiconductor bare chip or an IC chip encapsulated CSP (chip size package) is accommodated. Various wiring boards have also been proposed (see, for example, Patent Document 2). Here, the surface area occupied by the recess or cavity is considerably larger than the surface area occupied by the through hole.

In this way, the circuit board with a built-in element can set the surface mounting area surface or the wiring area surface widely by housing the functional element parts in the interlayer insulator layer of the wiring board. For this reason, high-density wiring and high-density mounting are further promoted, and the circuit board can be easily enhanced in function and size.
JP 2000-340955 A JP 2003-188314 A

  In storing functional element parts on the above-described element built-in circuit board, when the functional element and the wiring circuit are electrically connected by wire bonding, the interlayer insulator layer needs to have a required hardness to withstand the heat pressing of wire bonding. is there. Therefore, as the interlayer insulator, inorganic materials mainly composed of ceramics such as alumina or glass, thermosetting resin materials such as glass epoxy resin or polyimide resin, and composite materials thereof are suitable.

  However, in the case of a structure using an inorganic material, a thermosetting resin material or a composite material capable of ensuring the required hardness for the interlayer insulator layer, an adhesive for joining and integrating the outer layers of the multilayer wiring board It becomes essential to intervene, and the manufacturing process of the circuit board becomes complicated. Moreover, joining and integration by the insertion of an adhesive are accompanied by the flow of the adhesive and the like, and are liable to cause a decrease in reliability and generation of defective products. Furthermore, in the case of an inorganic material, a glass epoxy resin material, or a composite material, it is difficult to handle due to poor flexibility, and sometimes the wiring layer peels off. For this reason, a decrease in the reliability of the circuit board and the generation of defective products are promoted, and there are practical problems in terms of yield and productivity.

  Further, in the interlayer insulator layer made of the inorganic material, thermosetting resin material, or composite material, a wide area of the interlayer insulator layer is formed by laser in order to make a recess or cavity for housing the element component. Need to be processed. Here, a high-power laser such as a UV (far ultraviolet) -YAG (Yttrium Aluminum Garnet) laser or a carbon dioxide laser is required as the laser. For this reason, the manufacturing process of the circuit board with a built-in element becomes complicated, resulting in an increase in manufacturing cost and a difficulty in producing an inexpensive circuit board with a built-in element.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a low-cost element-embedded circuit board that is highly reliable, highly functional and compact, and a manufacturing method thereof.

In order to achieve the above object, an element-embedded circuit board according to the present invention includes a first wiring circuit formed of a metal foil, a second wiring circuit formed of a metal foil, and the first wiring circuit formed on a main surface. An insulating body made of a thermoplastic resin formed by laminating one wiring circuit and laminating the second wiring circuit on the other main surface so that a part of the second wiring circuit is exposed on the one main surface side An insulating layer forming a first recess capable of accommodating a functional element with a part exposed on the one main surface side of the second wiring circuit as a bottom portion, The functional element is attached to one wiring of the second wiring circuit exposed at the bottom of the first recess, and is exposed on the one main surface side of the insulator layer and is the same metal foil as the one wiring. other wiring and the functional element of the second wiring circuits that could have been a configuration that is connected with a bonding wire .

  According to the above invention, since the circuit board with a built-in element is formed of a thermoplastic resin, it is excellent in flexibility, high reliability, and can be produced at a high yield, so that it has excellent practicality. The element-embedded circuit board can freely mount various electronic components in required regions of the first wiring circuit and the second wiring circuit. For this reason, high-density mounting of electronic components such as functional elements becomes extremely easy, and the circuit board can be further enhanced in function and size.

  And the manufacturing method of the circuit board with a built-in element concerning this invention is a manufacturing method of the circuit board with a built-in element which accommodated the functional element inside, Comprising: The surface of the 1st metal foil was selectively etched, and several recessed parts and A step of forming a convex portion, and a step of laminating and arranging an insulating layer made of a thermoplastic resin and a second metal foil in this order on the surface side of the first metal foil on which the concave portion and the convex portion are formed. A step of integrating the laminated body arranged by heating and pressurizing, filling the concave portion with the insulator layer, and penetrating the convex portion to one main surface of the insulator layer; and the first metal foil And selectively etching the second metal foil to form a first wiring circuit made of the second metal foil on one main surface of the insulator layer, exposing the convex portion, and further A second wiring circuit made of one metal foil is connected to the other insulator layer. Forming a first recess by etching the protrusion of one wiring of the second wiring circuit to a predetermined depth from one main surface side of the insulator layer, A step of attaching a functional element to the one wiring in one recess, and a step of wire bonding to the upper surface of the convex portion of the other wiring of the functional element and the second wiring circuit. .

  According to the above invention, the first recess in which the functional element is accommodated can be formed by the etching process of a thin metal plate such as a copper foil that forms the wiring circuit. The manufacturing cost is reduced, and an inexpensive circuit board can be produced.

  In addition, in the electrical connection between the functional element housed in the first recess and the wiring circuit, the bonding wire is bonded to one wiring of the second wiring circuit that does not have an insulator layer made of a thermoplastic resin underneath. Is done. For this reason, even if the circuit board with a built-in element is heated in the wire bonding step, stable wire bonding is possible without being affected by thermal deformation of the insulator layer.

  Alternatively, the method for manufacturing a circuit board with a built-in element according to the present invention is a method for manufacturing a circuit board with a built-in element in which a functional element is housed, and the surface of the first metal foil is selectively etched to form a plurality of recesses and A step of forming a convex portion, and a step of laminating and arranging an insulating layer made of a thermoplastic resin and a second metal foil in this order on the surface side of the first metal foil on which the concave portion and the convex portion are formed. A step of integrating the laminated body arranged by heating and pressurizing, filling the concave portion with the insulator layer, and penetrating the convex portion to one main surface of the insulator layer; and the first metal foil And selectively etching the second metal foil to form a first wiring circuit made of the second metal foil on one main surface of the insulator layer, exposing the convex portion, and further A second wiring circuit made of one metal foil is connected to the insulating layer. Forming a first recess by etching the protrusion of one wiring of the second wiring circuit to a predetermined depth from one main surface side of the insulator layer; Etching the protrusions of the other wiring of the second wiring circuit to a predetermined depth from one main surface side of the insulator layer to form a second recess; and the one of the first recesses The method includes a step of attaching a functional element to the wiring, and a step of wire bonding to the functional element and the other wiring of the second recess.

  According to the invention, the bonding wire includes the functional element mounted on the second wiring circuit of the first recess provided in the insulator layer, and the first wiring through the second recess provided in the insulator layer. Bonding is performed with the wiring of the second wiring circuit located lower than the circuit. For this reason, the height of the bonding wire becomes a low loop, and the thickness of the sealing material for sealing the functional element can be reduced. In addition, portable devices such as IC cards are made thinner and more compact.

  Alternatively, the method for manufacturing a circuit board with a built-in element according to the present invention is a method for manufacturing a circuit board with a built-in element in which a functional element is housed, and the surface of the first metal foil is selectively etched to have a cross-sectional shape. A step of forming a plurality of concave portions and convex portions which are forward tapered, and an insulating layer made of a thermoplastic resin and a second metal foil on the surface side of the first metal foil on which the concave portions and the convex portions are formed. Are stacked in this order and integrated by heating and pressurization of the stacked stack, and the recess is filled with the insulator layer and the protrusion is inserted through one main surface of the insulator layer. And selectively etching the first metal foil and the second metal foil to form a first wiring circuit made of the first metal foil on the other main surface of the insulator layer, The second wiring circuit made of the second metal foil is mainly used as the insulator layer. Forming the first recess and the first recess on one wiring and the other wiring of the second wiring circuit by removing the convex portion of the first metal foil. And a step of attaching a functional element to the one wiring of the first recess, and a step of wire bonding to the functional element and the other wiring of the second recess.

  According to the above invention, the cross-sectional shape of the first recess in which the functional element such as the light emitting element is accommodated is easily controlled so as to have a forward taper. Moreover, the cross section of the first recess is constituted by an insulator layer made of a white liquid crystal polymer that has extremely high light reflectance. For this reason, the element-embedded circuit board containing the light-emitting elements highly reflects light emission in the cross section and increases the outgoing light rate. For example, it is extremely suitable for a backlight for a compact liquid crystal display device made of white light of a wavelength conversion type LED. In addition, it is extremely effective as a display device or lighting device for short, small and light portable devices.

  According to the configuration of the present invention, it is possible to provide a low-cost circuit board with a built-in element and a manufacturing method thereof that are highly reliable, capable of high functionality and compactness.

Several preferred embodiments of the present invention will be described below with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals.
(First embodiment)
An element-embedded circuit board and a manufacturing method thereof according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a main part showing one embodiment of a circuit board with a built-in element. 2 to 4 are cross-sectional views of the circuit board according to the process showing the method of manufacturing the element-embedded circuit board.

  In FIG. 1, the circuit board with a built-in element includes an interlayer insulator layer 1 made of a thermoplastic resin, a first wiring circuit 2 formed on one main surface of the interlayer insulator layer 1, and other main layers of the interlayer insulator layer 1. It has the 2nd wiring circuit 3 formed in the surface. One wiring 3a of the second wiring circuit 3 has a convex portion 4 in a part thereof, and the convex portion 4 penetrates the interlayer insulating layer 1 and is exposed on the one main surface. Further, the other wiring 3 b of the second wiring circuit 3 is provided with a recess 5 surrounded by the interlayer insulating layer 1 in a part thereof.

  Here, a plating layer 6 made of a composite layer of nickel (Ni) / gold (Au) or Ni / silver (Ag), for example, is formed on the surface of the protrusion 4 of the wiring 3a and the surface of the wiring 3b at the bottom of the recess 5. It is given to each. Similarly, the plating layer 6 made of the composite layer is also applied to the opening of the plating resist 7 covering the first wiring circuit 2 and the second wiring circuit 3.

  A semiconductor chip 8 is mounted (mounted) on a land portion composed of the wiring 3 b at the bottom of the recess 5, and a bonding wire 9 is connected to an electrode pad (not shown) of the semiconductor chip 8 and the convex portion 4. Further, a sealing resin 10 is formed on the entire surface so as to seal the semiconductor chip 8 in the recess 5 and cover the first wiring circuit 2. In this manner, the element built-in circuit board of the present embodiment accommodates and incorporates the semiconductor chip 8 having active elements or passive elements.

  In the said embodiment, as a thermoplastic resin used for the interlayer insulator layer 1, liquid crystal polymer (LCP), a phenoxy resin, a polyether sulfone resin, a polysulfone resin, a polyphenylene sulfone resin, a polyphenylene sulfide resin, a polyphenyl ether resin, for example. , Polyetherimide resin, thermoplastic polyimide resin, polytetrafluoroethylene resin, and the like. In particular, the LCP is extremely suitable because it has high heat resistance and high dielectric constant stability.

  Further, the first wiring circuit 2 and the second wiring circuit 3 are preferably formed of a metal foil (including a metal thin plate) such as a copper foil as will be described later in the method of manufacturing an element-embedded circuit board. is there.

  Next, a method for manufacturing the element-embedded circuit board will be described. As shown in FIG. 2A, first, a first copper foil 11 having a thickness of 50 to 100 μm is prepared. Then, an etching resist 12 having a predetermined pattern is formed on the surface of the first copper foil 11, and an etching resist 13 that covers the entire back side of the first copper foil 11 is formed. Here, the etching resist is formed by a required patterning by a known photosensitive resin film formed by spin coating or screen printing, and exposure / development.

  Next, the first copper foil 11 is etched using the etching resists 12 and 13 as an etching mask by immersing in an etching solution of a chemical solution made of, for example, an aqueous cupric chloride solution or an aqueous iron chloride solution. In this manner, as shown in FIG. 2B, a recess 14 having a depth of, for example, about 30 to 80 μm is formed on the surface of the first copper foil 11a so as to be approximately the same as the thickness of the semiconductor chip 8. Form. Here, as the etching solution, a ferric chloride aqueous solution is particularly preferable. By using this etching solution, it becomes easy to control the shape of the side wall of the deep recess 14 vertically. Further, after the etching process, chemical polishing such as treatment with a sulfuric acid-hydrogen peroxide solution, blackening treatment, or mechanical polishing such as buffing or brushing may be performed. Such a treatment improves the adhesion between the interlayer insulator layer and the copper foil in the production of a double-sided copper-clad laminate described below.

  Next, as shown in FIG. 2 (c), an LCP film which is a thermoplastic resin having a thickness substantially equal to the concave portion 14, for example, about 30 to 80 μm, on the surface side where the concave portion 14 of the first copper foil 11a is formed. 15 is further arranged, and a second copper foil 16 having a thickness of 20 to 35 μm is further laminated to form a laminate. Here, as the LCP film 15, for example, LCP cast (trade name) manufactured by Sumitomo Chemical Co., Ltd., Bexter (trade name) manufactured by Kuraray Co., Ltd. and the like can be suitably used.

Then, as shown in FIG.2 (d), a contact plate is arrange | positioned on both the copper foils 11a and 16 surfaces of the said laminated body, and it heat-presses and integrates as resin pressure, for example at about 30-100 kg / cm < ² >. A double-sided copper-clad laminate 17 is produced. Here, the convex portion of the first copper foil 11 a penetrates the LCP film 15 and reaches the second copper foil 16.

  Next, as shown in FIG. 3A, an etching resist 18 having the first wiring circuit 2 is formed on the surface of the double-sided copper-clad laminate 17, and further, a second side is formed on the back side of the double-sided copper-clad laminate 17. An etching resist 18 having the wiring circuit 3 is formed.

  Then, the copper foils 11a of the double-sided copper clad laminate 17 are immersed in an etching solution such as a cupric chloride aqueous solution, an iron chloride aqueous solution, or a sulfuric acid-hydrogen peroxide aqueous solution, and the etching resists 18 and 19 are used as an etching mask. 16 are etched. When the insulating resin is slightly present at the interface between the copper foils 11a and 16, it is preferable to perform mechanical polishing such as buffing or brushing or chemical polishing using a solution such as a polyimide etching solution. In this way, as shown in FIG. 3B, the first wiring circuit 2, the wiring 3a having the convex portion 4, and the wiring 3b having the convex portion 20 are formed.

  Thereafter, as shown in FIG. 3C, an etching resist 21 having a predetermined pattern is formed on the surface of the double-sided copper-clad laminate 17 on which the wiring circuits 2 and 3 are formed so as to expose the protrusions 20. Further, an etching resist 22 that covers the entire back side of the double-sided copper-clad laminate 17 is formed.

  Then, for example, a chemical solution made of an aqueous ferric chloride solution is used, and the double-sided copper-clad laminate 17 is immersed in the chemical solution using the etching resists 21 and 22 as an etching mask. Etch to a depth. In this way, as shown in FIG. 3D, a recess 5 surrounded by the interlayer insulator layer 1 is provided in a part on the wiring 3b. In FIG. 3D, the depth of the recess 5 is shown to be the same as that of the recess 14, but it may be set to the required depth. The planar dimension of the recess 5 is as wide as, for example, 10 mm × 10 mm depending on the size of the semiconductor chip 8 to be accommodated.

  Next, as shown in FIG. 4A, a plating resist 7 having a pattern covering a predetermined region is formed. Here, the plating resist 7 is formed by a required patterning by a known photosensitive resin film formed by spin coating or screen printing, and exposure / development. Then, a plating layer made of, for example, a composite layer of Ni / Au is formed on the surface of the convex portion 4, the surface of the wiring 3 b at the bottom of the recess 5, and a predetermined region of the first wiring circuit 2 and the second wiring circuit 3. 6 is formed. Here, for example, a Ni layer having a thickness of about 3 μm is formed by plating, and an Au layer having a thickness of about 1 μm is formed thereon by plating.

  Subsequently, as shown in FIG. 4B, the semiconductor chip 8 is attached to the surface of the plating layer 6 in the land portion composed of the wiring 3b at the bottom of the recess 5 by, for example, Ag paste. Then, as shown in FIG. 4C, a bonding wire 9 is connected to the electrode pad (not shown) of the semiconductor chip 8 and the plating layer 6 of the projection 4 of the wiring 3a by, for example, ultrasonic bonding. The surface dimension of the convex part 4 only needs to be large enough to bond the bonding wire 9. For example, one side of the rectangle is about 50 μm to 100 μm.

  Finally, the sealing resin 10 shown in FIG. 1 is formed on the entire surface. As described above, the circuit board with a built-in element according to the first embodiment is formed. Here, the sealing resin 10 may be a thermosetting resin such as an epoxy resin or an acrylic resin, or may be the above thermoplastic resin.

  In the present embodiment, the interlayer insulator layer 1 is formed of a thermoplastic resin. For this reason, the circuit board with a built-in element has excellent flexibility, is easy to handle, has high reliability as a circuit board, and can be produced at a high yield.

  The recess 5 for housing the semiconductor chip 8 in the circuit board with the built-in element immerses the double-sided copper-clad laminate 17 in a chemical solution, and etches the convex portion 20 of the first copper foil 11a to a required depth. Formed. In this case, the copper foil etching apparatus for forming a normal wiring circuit pattern can be used as it is, and the laser processing of the wide region of the interlayer insulating layer described in the prior art is completely unnecessary. For this reason, the manufacturing process of the circuit board with a built-in element is greatly simplified, the manufacturing cost is reduced, and an inexpensive circuit board can be produced.

  Further, in the electrical connection between the semiconductor chip 8 accommodated in the recess 5 and the wiring circuit, the bonding wire 9 is wire-bonded to one wiring of the second wiring circuit 3. For this reason, even if the element built-in circuit board is heated in the wire bonding step, stable wire bonding is possible. This is because there is no thermoplastic resin underneath, unlike wire bonding to one wiring of the first wiring circuit. When wire bonding is performed to the first wiring circuit 2 on the interlayer insulating layer 1 made of the thermoplastic resin, the interlayer insulating layer 1 is easily deformed by the heating, and therefore the first wiring thereon Bonding failure with the circuit 2 is likely to occur.

  In the element-embedded circuit board, various electronic components are further mounted in required regions of the first wiring circuit 2 and the second wiring circuit 3. In this manner, the element-embedded circuit board described in the present embodiment facilitates high-density mounting of functional element parts, and enables further enhancement of function and compactness of the circuit board.

(Second Embodiment)
Next, an element built-in circuit board and a method for manufacturing the same according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a cross-sectional view of an essential part showing another aspect of the circuit board with a built-in element. 6 to 8 are sectional views of the circuit boards according to the process showing the method of manufacturing the element built-in circuit board.

  In FIG. 5, the circuit board with a built-in element includes an interlayer insulator layer 1 made of a thermoplastic resin, a first wiring circuit 2 formed on one main surface of the interlayer insulator layer 1, and another main layer of the interlayer insulator layer 1. It has the 2nd wiring circuit 3 formed in the surface. The one wiring 3a and the other wiring 3b of the second wiring circuit 3 are each provided with a recess 23 and a recess 5 surrounded by the interlayer insulating layer 1.

  Here, the surface of the wiring 3a and the wiring 3b at the bottom of the recess 23 and the bottom of the recess 5 and the opening of a part of the plating resist 7 covering the second wiring circuit 3, for example, Ni / Au or Ni / A plating layer 6 made of a composite layer of Ag is applied.

  The semiconductor chip 8 is mounted on the land portion of the wiring 3b at the bottom of the recess 5, and the bonding wire 9 is connected to the electrode pad (not shown) of the semiconductor chip 8 and the one wiring 3a exposed at the recess 23. ing. Further, a sealing resin 10 is formed on the entire surface so as to seal the semiconductor chip 8 in the recess 5 and cover the first wiring circuit 2. In this manner, the element built-in circuit board of the present embodiment incorporates the semiconductor chip 8 having an active element or a passive element.

  In the above embodiment, the interlayer insulator layer 1 is made of a thermoplastic resin such as the LCP described in the first embodiment. The first wiring circuit 2 and the second wiring circuit 3 are preferably formed of a metal foil such as a copper foil.

  Next, a method for manufacturing the element built-in circuit board according to the second embodiment will be described. As shown in FIG. 6A, as in the case of the first embodiment, for example, a first copper foil 11 of 50 to 100 μm is prepared. Then, an etching resist 24 having a predetermined pattern is formed on the surface of the first copper foil 11, and further an etching resist 25 that covers the entire back side of the first copper foil 11 is formed.

  Next, the first copper foil 11 is etched by immersing it in an etching solution of ferric chloride aqueous solution, which is a chemical solution, for example, using the etching resists 24 and 25 as an etching mask. In this way, as shown in FIG. 6B, a recess 14 having a depth of about 30 to 80 μm, which is about the same as the thickness of the semiconductor chip 8, is formed on the surface of the first copper foil 11b.

  Next, as shown in FIG. 6 (c), an LCP film 15 which is a thermoplastic resin having a thickness substantially equal to the concave portion 14 is disposed on the surface side where the concave portion 14 of the first copper foil 11b is formed, and Further, a second copper foil 16 having a thickness of 20 to 35 μm is laminated to form a laminate. And as shown in FIG.6 (d), both the copper foils 11b and 16 of the said laminated body are heat-pressed and integrated, and the double-sided copper clad laminated board 17 is produced. Here, the convex portion of the first copper foil 11 b reaches the second copper foil 16 through the LCP film 15.

  Next, as shown in FIG. 7A, an etching resist 26 having the first wiring circuit 2 is formed on the surface of the double-sided copper-clad laminate 17, and further a second side is formed on the back side of the double-sided copper-clad laminate 17. An etching resist 27 having the wiring circuit 3 is formed.

  Then, for example, the copper foils 11b and 16 of the double-sided copper clad laminate 17 are etched by immersing in an etching solution of a ferric chloride aqueous solution that is a chemical solution and using the etching resists 26 and 27 as an etching mask. In this way, as shown in FIG. 7B, the first wiring circuit 2 and the wiring 3a and the wiring 3b constituting the second wiring circuit are formed. Further, the convex portion that has penetrated the interlayer insulator layer 1 of the wiring 3a and the wiring 3b and reached the second copper foil 16 is etched to a required depth. In this way, the recess 5 surrounded by the interlayer insulator layer 1 is provided on the wiring 3b, and the recess 23 surrounded by the interlayer insulator layer 1 is provided on the wiring 3a.

  In FIG. 7B, the depths of the recess 5 and the recess 23 are shown to be the same as those of the recess 14, but these depths can be freely set so as to be the required depth. Good. Here, the planar dimension of the recess 5 is as wide as 10 mm × 10 mm, for example, depending on the size of the semiconductor chip 8 to be accommodated. On the other hand, the planar dimension of the recess 23 only needs to be large enough to bond the bonding wire 9, and for example, one side of the rectangle may be about 50 μm to 100 μm.

  Subsequently, the etching resists 26 and 27 are peeled off using an organic solvent by a known method to obtain a circuit board as shown in FIG.

  Next, as shown in FIG. 8A, a plating resist 7 having a pattern covering a predetermined region is formed in the same manner as described in the first embodiment. Then, a plated layer 6 made of, for example, a Ni / Au composite layer is formed on the surfaces of the wiring 3 a and the wiring 3 b at the bottom of the recess 23 and the bottom of the recess 5 and a predetermined region of the second wiring circuit 3.

  Subsequently, as shown in FIG. 8B, the semiconductor chip 8 is attached and attached to the surface of the plating layer 6 in the land portion composed of the wiring 3b at the bottom of the recess 5 by, for example, Ag paste. Then, as shown in FIG. 8C, an electrode pad (not shown) of the semiconductor chip 8 and, for example, the plating layer 6 at the bottom of the recess 23 of the two wirings 3a are bonded to the bonding wire 9 using, for example, an ultrasonic bonding method. Connect with.

  Finally, the sealing resin 10 shown in FIG. 5 is formed on the entire surface in the same manner as described in the first embodiment. As described above, the circuit board with a built-in element according to the second embodiment is formed.

  In this embodiment, the same effect as described in the first embodiment is produced. Furthermore, in this embodiment, the bonding wire 9 becomes a low loop, and the film thickness of the sealing resin 10 can be made thinner than in the case of the first embodiment. The effect is that the bonding wire 9 is bonded to the convex portion 4 of the first wiring circuit 3 in the first embodiment, whereas in this case, the bottom of the recess 23 that is positioned lower than the convex portion 4. Results from being bonded to. Here, when the diameter of the bonding wire 9 is, for example, 20 μmφ, the height of the bonding wire 9 is reduced by 30 to 60 μm, and accordingly, the thickness of the sealing resin 10 can be reduced by 30 to 60 μm. In this way, for example, an element-embedded circuit board having an overall thickness of about 350 to 400 μm can be easily realized.

  The element-embedded circuit board further reduces the thickness of the IC card, for example, or facilitates further downsizing of the portable device.

(Third embodiment)
Next, an element built-in circuit board and a method for manufacturing the same according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a cross-sectional view of an essential part showing still another aspect of the circuit board with a built-in element. 10 to 12 are sectional views of the circuit boards according to the process showing the method of manufacturing the element built-in circuit board.

  In FIG. 9, the circuit board with a built-in element includes an interlayer insulator layer 1 made of thermoplastic resin, a first wiring circuit 2 (not shown) formed on one main surface of the interlayer insulator layer 1, an interlayer insulator layer. 1 has a second wiring circuit 3 formed on the other main surface. The one wiring 3a and the other wiring 3b of the second wiring circuit 3 are provided with a recess 23a and a recess 5a surrounded by the interlayer insulator layer 1, respectively. And as a characteristic matter in the present embodiment, at least the recess 5a is formed in a forward tapered shape. The recess 23a may also be formed in a forward tapered shape.

  Here, for example, a Ni / Ag composite layer is formed at the bottom of the recess 23 a and the surfaces of the wiring 3 a and the wiring 3 b at the bottom of the recess 5 a and a part of the opening of the plating resist 7 covering the second wiring circuit 3. A plating layer 6 made of is applied.

  The semiconductor chip 8 is mounted on the land portion of the wiring 3b at the bottom of the forward tapered recess 5a, and the bonding wire 9 is connected to the electrode pad (not shown) of the semiconductor chip 8 and the wiring 3a at the bottom of the recess 23a. Has been. Here, the semiconductor chip 8 is preferably a semiconductor LED (Light Emitting Diode). Specific examples thereof include a semiconductor LED that constitutes an excitation light source of a so-called wavelength conversion LED that emits ultraviolet light, blue light, etc. to excite a phosphor, or emits or displays visible light of the three primary colors of colored light. There are semiconductor LEDs that serve as direct light sources.

  A sealing resin 28 is formed on the entire surface so as to seal the semiconductor chip 8 in the recess 5 a and cover the first wiring circuit 2. Here, the sealing resin 28 is a transparent resin that transmits the light emitted from the semiconductor LED or a transparent resin in which a phosphor or the like is mixed.

  In this embodiment, the interlayer insulator layer 1 is particularly preferably an LCP with high light reflectivity. The first wiring circuit 2 and the second wiring circuit 3 may be formed of copper foil.

  Next, a method for manufacturing the element built-in circuit board according to the third embodiment will be described. As shown in FIG. 10A, as in the case of the first embodiment, for example, a first copper foil 11 of 50 to 100 μm is prepared. Then, an etching resist 29 having a predetermined pattern is formed on the surface of the first copper foil 11, and an etching resist 30 that covers the entire back side of the first copper foil 11 is formed.

  Next, the first copper foil 11 is etched using the etching resists 29 and 30 as an etching mask by immersing in an etching solution of a cupric chloride aqueous solution that is a chemical solution, for example. In this way, as shown in FIG. 10B, a recess 14a having a depth of about 30 to 80 μm, which is about the same as the semiconductor chip 8, is formed on the surface of the first copper foil 11c. Here, the etching solution of the above-mentioned cupric chloride aqueous solution is a suitable chemical solution that makes the cross-sectional shape of the recess 14a a forward tapered shape.

  Next, as shown in FIG. 10 (c), the LCP film 15 which is a thermoplastic resin having a thickness substantially equal to the concave portion 14a is disposed on the surface side where the concave portion 14a of the first copper foil 11c is formed, Further, a second copper foil 16 having a thickness of 20 to 35 μm is laminated to form a laminate. And as shown in FIG.10 (d), both the copper foils 11c and 16 of the said laminated body are heat-pressed and integrated, and the double-sided copper clad laminated board 17 is produced. Here, the convex portion of the first copper foil 11 c reaches the second copper foil 16 through the LCP film 15.

  Next, as shown in FIG. 11A, the double-sided copper clad laminate 17 is turned upside down so that the first copper foil 11c is the front side and the second copper foil 16 is the back side. Then, an etching resist 31 having the second wiring circuit 3 is formed on the back side of the double-sided copper-clad laminate 17. Here, an etching resist having the first wiring circuit 2 is also formed in a predetermined region on the front side of the double-sided copper-clad laminate 17 but is not shown.

  Then, for example, the copper foils 16 and 11c of the double-sided copper clad laminate 17 are etched by immersing in an etching solution of a ferric chloride aqueous solution that is a chemical solution and using the etching resist 31 as an etching mask. By this etching process, as shown in FIG. 11B, a wiring 3a that is one wiring of the second wiring circuit 3 and a wiring 3b that is another wiring are formed. Further, the first copper foil 11c is etched leaving the predetermined region. Here, all the forward taper-shaped convex parts which the 1st copper foil 11c penetrated the interlayer insulator layer 1 and reached the 2nd copper foil 16 are removed by etching. Thus, the forward tapered recess 5a surrounded by the interlayer insulator layer 1 on the wiring 3b formed by etching the second copper foil 16 and the interlayer insulator layer 1 on the wiring 3a. An enclosed forward tapered recess 23a is provided.

  In FIG. 11B, the depth of the recess 5a and the recess 23a is the same as that of the recess 14a. Here, if the convex part of the 1st copper foil 11c which penetrated the said LCP film 15 electrically connects with the 2nd copper foil 16, in the etching process of both the said copper foils 16 and 11c, the said convex part May be etched to a required depth. In this case, the depths of the recess 5a and the recess 23a are shallower than the depth of the recess 14a. The planar dimension of the recess 5a is, for example, about 1 mm to 2 mm on one side of the rectangle depending on the size of the semiconductor LED to be stored. On the other hand, the planar dimension of the recess 23a is about 50 μm to 100 μm on one side of the rectangle.

  Subsequently, the etching resist such as the etching resist 31 is peeled off using an organic solvent by a known method to obtain a circuit board as shown in FIG.

  Next, as shown in FIG. 12A, a plating resist 7 having a pattern covering a predetermined region is formed. Then, a plating layer 6 made of, for example, a composite layer of Ni / Ag is formed on the surfaces of the wiring 3a and wiring 3b at the bottom of the recess 23a and the bottom of the recess 5a and a predetermined region of the second wiring circuit 3.

  Subsequently, as shown in FIG. 12B, the semiconductor LED semiconductor chip 8 is attached to the surface of the plating layer 6 in the land portion composed of the wiring 3b at the bottom of the recess 5a by, for example, Ag paste. Then, as shown in FIG. 12C, the respective bonding wires 9 are ultrasonically bonded to the electrode pads (not shown) of the semiconductor chip 8 and the plating layer 6 at the bottom of the recess 23a of the wiring 3a.

Here, the semiconductor LED of said excitation light source, for example, _{Mg x Zn 1-x O,} In x Al y Ga (1-x-y) N, GaN -based semiconductor layer, InGaN-based semiconductor layer, an AlGaN-based semiconductor layer There are semiconductor LEDs consisting of compound semiconductors. Alternatively, the direct-source semiconductor LED that emits green light to red light includes, for example, a compound semiconductor layer such as an InAlGaP-based semiconductor layer, a GaAsP semiconductor layer, a GaP semiconductor layer, and an AlGaAs semiconductor layer. In addition, materials such as SiC, Al ₂ O ₃ (sapphire), ZnSe, and ZnS may be used.

  Finally, the sealing resin 28 shown in FIG. 9 is formed on the entire surface. As described above, the circuit board with a built-in element according to the third embodiment is formed. Here, as the transparent resin constituting the sealing resin 28, a colorless and transparent epoxy resin, acrylic resin, or silicone resin is extremely suitable. Furthermore, it is preferable to add a colorless, transparent, and highly reflective material as a light dispersion material to the sealing resin 28 without loss of light emission. Examples of such materials include silicon oxide, aluminum oxide, calcium carbonate, barium oxide, titanium oxide, barium sulfate, and epoxy resin.

Further, in the case of the wavelength conversion type LED described above, a required phosphor is added to the sealing resin 28. Such a phosphor emits light at a wavelength that is excited by light from the semiconductor LED and shifted to the longer wavelength side. For example, A ₃ B ₅ O ₁₂ : M (A: Y, Gd, Lu, Tb, etc. B: Al, Ga M: Ce ³⁺ , Tb ³⁺ , Eu ³⁺ , Cr ³⁺ , Nd ³⁺ , Er ³⁺ etc.), ABO ₃ : Aluminate such as M (A: Y, Gd, Lu, Tb B: Al, Ga M: Ce ³⁺ , Tb ³⁺ , Eu ³⁺ , Cr ³⁺ , Nd ³⁺ , Er ³⁺ ), or (Ba, Ca, _Eu) x _Si y _O z: orthosilicates such as ^{Eu 2+} and the like as examples.

  Then, for example, a YAG (Yttrium Aluminum Garnet) phosphor is excited by blue light from a GaN-based semiconductor LED, and yellow fluorescent light is emitted to generate white light that is a mixed color thereof. Alternatively, a plurality of phosphors mixed in the sealing resin 28 are excited by ultraviolet light from the semiconductor LED, and white light is generated by emitting, for example, three primary colors of red, green, and blue fluorescence.

  In the present embodiment, the same effect as described in the first and second embodiments is also produced. The circuit board with a built-in element is extremely useful as a compact backlight for liquid crystal display devices made of white light of the wavelength conversion LED. In addition, it is also suitable as a display device or illumination device for short, small and light portable devices.

  Further, in this embodiment, since the recess 5a in which the semiconductor chip 8 is accommodated is formed in a forward tapered shape, the light emitted from the semiconductor chip 8 is reflected by the forward tapered side wall of the interlayer insulator layer 1, The light emission rate to the sealing resin 28 is improved. Further, by forming the interlayer insulator layer 1 with, for example, a white LCP film 15, the amount of reflection increases. And the illumination intensity of the said display apparatus or an illuminating device improves.

  In the third embodiment, other light emitting elements may be accommodated as the semiconductor chip 8. For example, an organic EL element utilizing the electroluminescence (EL) phenomenon of an organic thin film may be used.

  The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the 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.

  For example, in the above-described embodiment, an element-embedded circuit board made of the double-sided copper-clad laminate is used as an inner layer board, and so-called prepregs and wiring pattern layers are laminated as required on both sides to form a multilayer wiring structure. May be.

  Moreover, in the said embodiment, although the wiring circuit of a circuit board is formed from copper foil or a thin plate, you may form by etching the copper foil or thin plate which consists of another metal material.

  In the third embodiment, the sealing of the semiconductor chip 8 with the sealing resin 28 may be colorless and transparent glass sealing. Alternatively, instead of the sealing resins 10 and 28, an interlayer insulator layer such as a prepreg used for forming a multilayer wiring board may be used as a sealing material.

  Further, in the circuit board with a built-in element of the present invention, the functional element component that is electrically connected to the wiring circuit by the joining means using solder bumps or ball bumps may be housed in the first recess.

1 is a cross-sectional view of a main part showing one aspect of an element built-in circuit board according to a first embodiment of the present invention. (A) thru | or (d) is a circuit board sectional drawing according to process which shows one manufacturing process of the circuit board with a built-in element concerning the 1st Embodiment of this invention. (A) And (d) is the circuit board sectional drawing according to process which shows the manufacturing process of the circuit board with a built-in element following FIG. (A) And (c) is a circuit board sectional view according to process which shows a manufacturing process of an element built-in circuit board following Drawing 3. The principal part sectional view showing one mode of the circuit board with a built-in element concerning a 2nd embodiment of the present invention. (A) thru | or (d) is a circuit board sectional drawing according to process which shows one manufacturing process of the circuit board with a built-in element concerning the 2nd Embodiment of this invention. (A) And (c) is a circuit board sectional view according to process which shows a manufacturing process of an element built-in circuit board following Drawing 6. (A) And (c) is a circuit board sectional view according to process which shows the manufacturing process of the circuit board with a built-in element following Drawing 7. Sectional drawing which shows the principal part which shows the one aspect | mode of the circuit board with a built-in element concerning the 3rd Embodiment of this invention. (A) thru | or (d) are circuit board sectional drawings according to process which show one manufacturing process of the circuit board with a built-in element concerning the 3rd Embodiment of this invention. (A) And (c) is the circuit board sectional drawing according to process which shows the manufacturing process of the circuit board with a built-in element following FIG. (A) And (c) is a circuit board sectional view according to process which shows a manufacturing process of a circuit board with a built-in element following Drawing 11.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Interlayer insulator layer, 2 ... 1st wiring circuit, 3 ... 2nd wiring circuit, 3a, 3b ... wiring, 4, 20 ... Convex part, 5, 5a, 23, 23a ... Recessed part, 6 ... Plating Layer, 7 ... plating resist, 8 ... semiconductor chip, 9 ... bonding wire, 10, 28 ... sealing resin, 11, 11a, 11b, 11c ... first copper foil, 12, 13, 18, 19, 21, 22 24, 25, 26, 27, 29, 30, 31 ... Etching resist, 14, 14a ... Recess, 15 ... LCP film, 16 ... Second copper foil, 17 ... Double-sided copper-clad laminate

Claims (7)

A first wiring circuit formed of metal foil;
A second wiring circuit formed of metal foil;
Heat formed by laminating the first wiring circuit on one main surface and laminating the second wiring circuit on the other main surface so that a part of the second wiring circuit is exposed on the one main surface side An insulator layer made of a plastic resin, the insulator layer forming a first recess capable of accommodating a functional element with a part exposed on the one main surface side of the second wiring circuit as a bottom portion And
The functional element is mounted on one wiring of the second wiring circuit exposed at the bottom of the first recess, and is exposed on the one main surface side of the insulator layer and is the same metal foil as the one wiring A circuit board with a built-in element, characterized in that the other wiring of the second wiring circuit made of and the functional element are connected by a bonding wire. A portion of the other wiring has a protrusion that penetrates the insulator layer and is exposed to the one main surface side;
The element built-in circuit board according to claim 1, wherein the bonding wire is bonded to an upper surface of the convex portion. A second recess formed in the insulator layer in a part of the other wiring;
2. The element built-in circuit board according to claim 1, wherein the bonding wire is bonded to the other wiring exposed to the one main surface side at the bottom of the second recess. 4. The element built-in circuit board according to claim 1, wherein a cross-sectional shape of the first recess is a forward taper. A method of manufacturing an element-embedded circuit board that houses functional elements therein,
Selectively etching the surface of the first metal foil to form a plurality of recesses and protrusions;
A step of laminating and arranging an insulating layer made of a thermoplastic resin and a second metal foil in this order on the surface side of the first metal foil in which the concave and convex portions are formed;
The step of integrating the laminated body arranged by heating and pressurizing, filling the concave portion with the insulator layer, and penetrating the convex portion to one main surface of the insulator layer;
The first metal foil and the second metal foil are selectively etched to form a first wiring circuit made of the second metal foil on one main surface of the insulator layer, and the convex portion Exposing the second wiring circuit made of the first metal foil on the other main surface of the insulator layer; and
Etching the convex portion of one wiring of the second wiring circuit from the main surface side of the insulator layer to a predetermined depth to form a first recess;
Attaching a functional element to the one wiring of the first recess;
Wire bonding to the upper surface of the convex portion of the other wiring of the functional element and the second wiring circuit;
A method of manufacturing a circuit board with a built-in element, comprising: A method of manufacturing an element-embedded circuit board that houses functional elements therein,
Selectively etching the surface of the first metal foil to form a plurality of recesses and protrusions;
A step of laminating and arranging an insulating layer made of a thermoplastic resin and a second metal foil in this order on the surface side of the first metal foil in which the concave and convex portions are formed;
The step of integrating the laminated body arranged by heating and pressurizing, filling the concave portion with the insulator layer, and penetrating the convex portion to one main surface of the insulator layer;
The first metal foil and the second metal foil are selectively etched to form a first wiring circuit made of the second metal foil on one main surface of the insulator layer, and the convex portion Exposing the second wiring circuit made of the first metal foil on the other main surface of the insulator layer; and
Etching the convex portion of one wiring of the second wiring circuit from the main surface side of the insulator layer to a predetermined depth to form a first recess;
Etching the convex portion of the other wiring of the second wiring circuit to a predetermined depth from one main surface side of the insulator layer to form a second recess;
Attaching a functional element to the one wiring of the first recess;
Wire bonding the functional element and the second wiring in the second recess;
A method of manufacturing a circuit board with a built-in element, comprising: 7. The method of manufacturing a circuit board with a built- in element according to claim 5, wherein the first recess has a forward taper in cross-sectional shape .

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