JP2007019268A - Wiring board and manufacturing method thereof, and electronic equipment incorporating wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board that can be miniaturized, and a method of manufacturing the wiring board. <P>SOLUTION: The wiring board 10 has two core materials 11, 12, and a resin layer 22 sandwiched between the two core materials 11, 12. Copper foil existing on the inner surface of the core member 11 is etched to form a pad 15', and an electronic component 20 is packaged onto the pad 15'. The core material 12 is oppositely arranged via the resin layer 22, and the electronic component 20 is sandwiched between the two core materials 11, 12 to form the laminated wiring board 10. A hole 24 (26) is formed from the outer surface side of the core material 11 (12) toward the pad 15' (16'), and wiring is connected via the hole. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wiring board incorporating an electronic component, an electronic device incorporating the wiring board, and a method of manufacturing the wiring board.

  Conventionally, as a wiring board incorporating an electronic component, the electronic component is attached to the mounting surface of the core substrate via an adhesive and sealed with an insulating resin, and penetrated from the back side of the core substrate toward the electrode of the electronic component. There is known a wiring board in which holes are formed by laser processing and a circuit pattern connected to an electrode of an electronic component through the through hole is formed on the back surface of a core substrate (see Patent Document 1).

  According to this wiring board, since the circuit pattern is directly connected to the electrode of the electronic component attached to the core board through the through hole of the core board, no wiring is required on the mounting surface of the core board. The manufacturing process can be simplified.

However, when manufacturing the wiring board, when the through hole is formed in the core substrate by laser processing, the laser is directly irradiated toward the electrode of the electronic component, which causes a problem of damaging the electronic component.
JP 2004-296562 A (FIG. 1)

  The object of the present invention is to increase the product yield without damaging the built-in electronic components, and to realize a reduction in size of the wiring board, the electronic device incorporating the wiring board, and the wiring board It is to provide a manufacturing method.

  In order to achieve the above object, a wiring board according to the present invention includes a first board having a first pad, an electronic component connected to the first pad, and a first board facing the first board across the electronic part. Two substrates, and a resin layer on which the electronic component is laminated between the first and second substrates.

  Further, the method of manufacturing a wiring board according to the present invention includes a step of patterning a metal layer formed on an inner surface of a first substrate having metal layers on both sides to form a first pad on the inner surface, and the first pad. A mounting step of connecting the electronic component to the inner surface and mounting the electronic component on the inner surface; and a step of melting and laminating the resin layer with the second substrate facing the inner surface of the first substrate via the resin layer; And a hole forming step of forming a conduction hole connected from the outer surface of the first substrate to the first pad.

  Furthermore, the method for manufacturing a wiring board according to the present invention includes a step of patterning a metal layer formed on an inner surface of a first substrate having metal layers on both sides to form a first pad on the inner surface, and the first pad. A mounting step of connecting the electronic component to the inner surface and mounting the electronic component on the inner surface; and a step of melting and laminating the resin layer with the second substrate facing the inner surface of the first substrate via the resin layer; And a hole forming step of forming a conduction hole connected to the first pad by irradiating laser light from the outer surface of the first substrate toward the first pad.

  According to the above invention, when the conduction hole for connecting the first wiring from the outer surface side of the first substrate is formed, the laser is irradiated from the outer surface side of the first substrate toward the first pad. It is possible to prevent the electronic component from being damaged without directly irradiating the electrode of the component with the laser.

  According to the present invention, it is possible to reduce the size of the wiring board.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view partially enlarging a cross section of a wiring board 10 according to an embodiment of the present invention. For example, the wiring board 10 is incorporated in a casing 101 of an electronic device 100 such as a TV, a mobile phone, or a laptop computer (see FIG. 13). The wiring substrate 10 has a structure in which an electronic component 20 such as a capacitor or a chip resistor is disposed between two core materials 11 and 12 and sandwiched between resin layers 22. Here, the mounting structure of one electronic component 20 will be described as a representative, but a plurality of electronic components can be arranged between the two core members 11 and 12.

A method for manufacturing the wiring board 10 will be described below with reference to FIGS. 1 to 11 together with the flowchart shown in FIG.
First, a core material 11 (first substrate) as shown partially enlarged in FIG. 2 is prepared. The core material 11 is formed by laminating copper foils 15 and 17 (metal layers) on both surfaces of a flat substrate 13 made of, for example, a resin material (prepreg) containing glass fibers. In order to match the thermal expansion coefficient of the substrate 13 with the copper foils 15 and 17 and to suppress warping, glass fiber is mixed with the substrate 13. Thereby, the curvature of the core material 11 by heating can be suppressed. A core material 12 (second substrate) described later also has the same structure as the core material 11.

  Thereafter, as shown in FIG. 3, the copper foil 15 laminated on the one surface (inner surface) side of the prepared core material 11 is etched and patterned, and a pad 15 ′ (first) for connecting the electronic component 20 is formed. Pad) is formed (FIG. 12, step 1). At this time, a photoresist layer (not shown) is formed on the copper foil 15, a mask pattern (not shown) is formed by exposure and development, and the pad 15 ′ is formed by etching the copper foil 15 through the mask pattern. . The pad 15 ′ functions as a pad for electrically connecting the electrode terminals of the electronic component 20.

  Then, as shown in FIG. 4, the conductive paste 2 (conductive adhesive) is disposed on the portion where the electronic component 20 is connected on the pad 15 ′. At this time, the conductive paste 2 is formed on the pad 15 ′ by printing using a metal mask or syringe (not shown), for example. The conductive paste 2 is formed by mixing several kinds of metal materials 4 and an adhesive 6, and when heated and melted, the adhesive 6 is applied to the surface of the metal material 4 as shown in an enlarged view in FIG. 5. Has the property of appearing. That is, since the melting rate of the metal material 4 and the adhesive 6 are different and the surface tension is different, the adhesive 6 is deposited on the surface of the metal material 4. As the conductive paste 2 having such properties, for example, Sn-Bi + epoxy resin is known.

  Further, as shown in FIG. 6, the electrode terminal of the electronic component 20 is connected to the pad 15 'through the conductive paste 2, and the electronic component 20 is mounted on the inner surface of the core material 11 (step 2). The electronic component 20 is a small component such as a capacitor such as 0603 and 0402, a resistor, and an inductor. At this time, for example, the conductive paste 2 is heated and melted at a temperature of about 150 ° C. to 200 ° C. for about 3 to 10 minutes, preferably at a temperature of 170 ° C. for 5 minutes, and the surface is covered with the adhesive 6. The electrode terminal of the electronic component 20 and the pad 15 ′ are electrically connected with the metal material 4. The heating temperature and heating time at this time are set to temperatures and times at which several kinds of metal materials can be alloyed and the adhesive 6 can be deposited on the surface. The adhesive 6 deposited on the surface functions as a barrier for preventing the metal material 4 melted in the thermal process described later from flowing out.

  Since no other electronic components are mounted on the outer surface of the core material 11 when the electronic component 20 is mounted on the inner surface of the core material 11, there is no need to hold the core material 11 so as not to interfere with the electronic component on the outer surface side. The apparatus configuration can be simplified.

  After the electronic component 20 is mounted as described above, another core material 12 is arranged facing the inner surface of the core material 11 so as to sandwich the electronic component 20 via the resin layer 22 as shown in FIG. To do. The core material 12 also has the same structure as the core material 11 and is formed by laminating copper foils 16 and 18 on both surfaces of the prepreg substrate 14. In the present embodiment, the copper foil on the inner surface side where the core material 12 faces the core material 11 is also patterned by etching, and the pad 16 ′ (second pad) is formed in advance. Although not shown here, another electronic component may be mounted on the pad 16 ′ formed on the inner surface side of the core material 12 so as to be nested with the electronic component 20 mounted on the core material 11. A large number of electronic components can be mounted in the space.

  In this state, as shown in FIG. 8, the electronic component 20 is sandwiched between the two core materials 11 and 12 and heated and pressurized to melt the resin layer 22, so that the electronic component 20 is replaced with the two core materials 11 and 12. Laminate in between (step 3). As shown in FIG. 9, the resin layer 22 is formed by mixing a resin material 22 a with silica particles 22 b at a relatively high ratio, and is formed in a sheet shape that can be melted by heating.

  At this time, the conductive paste 2 connecting the electronic component 20 and the pad 15 ′ is also heated by the heating of the resin layer 22. However, since the conductive paste 2 of the present embodiment covers the surface of the metal material 4 with the adhesive 6 as shown in FIG. 5, the metal material 4 melted by heating does not flow out to the resin layer 22. .

  As described above, by using the resin layer 22 in which the silica particles 22b are mixed as the filler as the resin material as the resin material, the glass fiber is not hit and the electronic component 20 is not damaged as in the case of using the prepreg. That is, when the electronic component 20 is laminated by melting the resin layer 22, the filler does not move in the resin material so as to avoid the electronic component, and the electronic component 20 is not damaged.

  The filling amount of the filler 22b is adjusted so that the thermal expansion coefficients of the resin layer 22 and the electronic component 20 are substantially the same. Thereby, it can prevent that a crack originates in the difference in a thermal expansion coefficient.

  As described above, after the electronic component 20 is mounted on the core material 11 (12) and laminated between the two core materials 11 and 12, as shown in FIG. 10, the holes 24 ( A conduction hole) is formed from the outer surface side of the core material 11, and a hole 26 (conduction hole) connected to the pad 16 'is formed from the outer surface side of the core material 12 (steps 4 and 5). And the hole 28 which penetrates the two core materials 11 and 12 and the resin layer 22 is formed by drilling as needed.

When the hole 24 connected to the pad 15 ′ is formed by laser processing, for example, the copper foil 17 laminated on the outer surface side of the core material 11 needs to be partially removed (step 4). When a CO ₂ laser is used as the laser, if the laser is applied to the copper foil 17 with a laser intensity capable of making a hole in the substrate 13 of the core material 11, about 95% of the laser is reflected. For this reason, it is necessary to partially remove the copper foil 17 at the laser irradiation position before the laser irradiation. In this case, the laser irradiation position is a position facing the pad 15 ′ to which the electronic component 20 is connected, that is, a position where the hole 24 is formed.

  When the copper foil 17 is partially removed, a dry film is attached on the copper foil 17 and patterned to form a mask pattern with holes at positions where laser irradiation is performed. And the copper foil 17 is etched through the hole of this mask pattern, and a hole is opened in a laser irradiation position. Similarly, the copper foil 18 at the position where the hole 26 is formed is also partially removed.

  Then, laser is irradiated from the outer surface side of the core material 11 toward the pad 15 ′ through the hole of the copper foil 17 to form a hole 24 connected to the pad 15 ′ (step 5). In this case, there are a conformal mask method in which the hole of the copper foil 17 is used instead of a mask and laser is irradiated, and an open window method in which the laser is irradiated with a beam diameter smaller than the hole of the copper foil 17.

  In any case, in the present embodiment, the laser is not directly applied to the electrode terminal of the electronic component 20, but the pad 15 ′ is irradiated with the laser, and thus the electronic component 20 is damaged by the laser irradiation. There is no. Similarly, when the hole 26 is formed, the electrode terminal of the electronic component 20 is not damaged because the laser is irradiated from the outside of the core material 12 toward the pad 16 ′.

  In addition to this, there is a direct laser method as a method in which the step of opening a hole in advance at the laser irradiation position of the copper foil 17 is omitted. In this method, first, a laser is irradiated with a laser intensity capable of opening a hole in the copper foil 17, and after the hole is formed in the copper foil 17, the hole is formed in the substrate 13 by reducing the laser intensity to not penetrate the pad 15 ′. (Step 5). Thus, after penetrating the copper foil 17, the pad 15 'is not penetrated by irradiating the laser with low energy different from the first. That is, the electronic component 20 is not damaged by the laser irradiation.

  Thereafter, as shown in FIG. 11, a metal layer 35 is formed on the entire outer surface of the core materials 11 and 12 by plating, and finally, by etching, the holes 24, 26 and 28 are formed as shown in FIG. The metal layer 32 and the wiring 34 to cover are formed on the outer surface of each core material 11 and 12 (step 6). The wiring formed on the outer surface of the core material 11 functions as the first wiring of the present invention, and the wiring formed on the outer surface of the core material 12 functions as the second wiring of the present invention.

  In this manner, by directly forming the wirings 32 and 34 from the outer surface side of the core material 11 through the holes 24 on the pad 15 ′ to which the electrode terminals of the electronic component 20 are connected, the wiring length can be shortened and the degree of freedom in design The wiring space can be secured and the noise can be reduced.

  As described above, according to the present embodiment, the electronic component 20 is mounted on one side of the core material 11 (12) and the wiring is connected from the outer surface side of the core material. Manufacture can be facilitated compared with the case of mounting. In addition, since the electronic component 20 is sandwiched between the two core members 11 and 12 and laminated by the resin layer 22, wiring can be easily formed on the outer surface side of the core members 11 and 12, and the degree of freedom in design can be increased. .

  Further, according to the present embodiment, when the holes 24 and 26 for wiring are formed from the outer surface side of the core materials 11 and 12, the pad 15 ′ and the pad 16 ′ formed on the inner surfaces of the core materials 11 and 12, respectively. Since the laser is irradiated toward the surface, the electronic component 20 is not damaged and the product yield can be improved as compared with the conventional case where the laser is directly applied to the electrode of the electronic component.

  Furthermore, according to the present embodiment, since a plurality of electronic components 20 can be arranged between the two core materials 11 and 12, there is no need to arrange the electronic components 20 on the outer surface of the core materials 11 and 12, Thus, the space on the outer surface can be reduced, and as a result, the area of the wiring board can be reduced, and the wiring board can be downsized. Although it is conceivable that the thickness of the wiring board is increased by disposing the electronic component 20 between the two core materials 11 and 12, the height of the electronic component 20 itself can be reduced or the core material can be reduced. By arranging the electronic component mounted on 11 and the electronic component mounted on the core material 12 in a nested manner, the wiring board can be prevented from becoming thick.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, you may delete some components from all the components shown by embodiment mentioned above. Furthermore, you may combine the component covering different embodiment suitably.

  For example, in the above-described embodiment, the structure in which the electronic component 20 is laminated between the two core materials 11 and 12 has been described. However, the invention is not limited to this, and the electronic component is mounted on the outer side of the core materials 11 and 12. Thus, another core material may be laminated via the resin layer, and the number of core materials can be arbitrarily set. For example, when four core materials are laminated, electronic components can be mounted on the second and third core materials.

The partial expanded sectional view which expands and shows partially the structure of the principal part of the wiring board which concerns on embodiment of this invention. The figure for demonstrating the manufacturing method of the wiring board of FIG. The figure for demonstrating the manufacturing method of the wiring board of FIG. The figure for demonstrating the manufacturing method of the wiring board of FIG. The partial expanded sectional view which expands and shows partially the structure of the principal part of FIG. The figure for demonstrating the manufacturing method of the wiring board of FIG. The figure for demonstrating the manufacturing method of the wiring board of FIG. The figure for demonstrating the manufacturing method of the wiring board of FIG. The figure for demonstrating the structure of the resin layer arrange | positioned between two core materials in FIG. The figure for demonstrating the manufacturing method of the wiring board of FIG. The figure for demonstrating the manufacturing method of the wiring board of FIG. The flowchart for demonstrating the manufacturing method of the wiring board of FIG. Schematic which shows the electronic device which incorporated the wiring board of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11, 12 ... Core material, 13, 14 ... Board | substrate, 15, 16, 17, 18 ... Copper foil, 15 '... 1st wiring, 16' ... 3rd wiring, 20 ... Electronic component, 22 ... Resin layer, 24, 26, 28 ... holes, 32 ... metal layer, 34 ... wiring, 100 ... electronic equipment.

Claims (14)

A first substrate having a first pad;
An electronic component connected to the first pad;
A second substrate facing the first substrate across the electronic component;
A resin layer for laminating the electronic component between the first and second substrates;
A wiring board comprising:   The wiring board according to claim 1, further comprising a conduction hole connected to the first pad from an outer surface of the first board.   The wiring board according to claim 2, further comprising a first wiring formed on an outer surface of the first board so as to be connected to the first pad through the conduction hole.   The wiring board according to claim 1, wherein the electrode of the electronic component and the first pad are connected via a conductive adhesive.   The wiring board according to claim 1, wherein the resin layer is formed by mixing silica particles in a resin material.   The wiring substrate according to claim 5, wherein the silica particles are mixed with the resin material at a ratio such that the thermal expansion coefficients of the resin layer and the electronic component are substantially the same.   The wiring board according to claim 1, wherein a second pad is formed on an inner surface of the second substrate, and another electronic component is connected to the second pad.   A conduction hole connected to the second pad from the outer surface of the second substrate is formed, and a second wiring connected to the second pad through the conduction hole is formed on the outer surface of the second substrate. Item 8. The wiring board according to Item 7. Patterning a metal layer formed on an inner surface of a first substrate having metal layers on both sides to form a first pad on the inner surface;
A mounting step of connecting an electronic component to the first pad and mounting the electronic component on the inner surface;
A step of causing the second substrate to face the inner surface of the first substrate via the resin layer and melting and laminating the resin layer;
A hole forming step of forming a conduction hole connected from the outer surface of the first substrate to the first pad;
A method of manufacturing a wiring board, comprising:   In the mounting step, a conductive adhesive formed by mixing an adhesive that appears on the surface due to a difference in surface tension by heating and melting and a metal material is formed between the first pad and the electrode of the electronic component. The method for manufacturing a wiring board according to claim 9, wherein the wiring board is disposed between the first pad and the electrode by heating and melting the conductive adhesive.   The method for manufacturing a wiring board according to claim 9, further comprising a step of forming a first wiring connected to the first pad through the conduction hole on an outer surface of the first board. Patterning a metal layer formed on an inner surface of a first substrate having metal layers on both sides to form a first pad on the inner surface;
A mounting step of connecting an electronic component to the first pad and mounting the electronic component on the inner surface;
A step of causing the second substrate to face the inner surface of the first substrate via the resin layer and melting and laminating the resin layer;
A hole forming step of forming a conduction hole connected to the first pad by irradiating laser light from the outer surface of the first substrate toward the first pad;
A method of manufacturing a wiring board, comprising:   The hole forming step includes a step of patterning a metal layer formed on an outer surface of the first substrate and removing the metal layer at a laser irradiation position before irradiating the laser beam. Item 13. A method for manufacturing a wiring board according to Item 12.   An electronic device comprising: the wiring board according to claim 1; and a housing having the wiring board built therein.

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