JP2013021126A - Method of manufacturing multilayer substrate, and multilayer substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a multilayer substrate which can achieve inexpensive formation of the multilayer substrate by simplifying manufacturing steps, and the multilayer substrate.SOLUTION: A second substrate 22 having a via hole 23 is formed on one surface 21a of a first substrate 21 so that the second substrate 22 is adhered to the first substrate 21 and a land 34 of a first conductor pattern 31 is exposed from the via hole 23. Then, a second conductor pattern 32 is formed by punching a metal foil 25 into a predetermined shape by heat press, and a second wire 35 is formed by allowing a part of the second conductor pattern 32 to be thermocompressed against one surface 22b of the second substrate 22. The rest of the second conductor pattern 32 is pushed in the via hole 23, and an interlayer connection part 36 is formed by allowing a part of the second conductor pattern 32 thus pushed in to extend along an inclined surface 23a of the via hole 23, and by allowing the part of the second conductor pattern 32 thus pushed in to be thermocompressed against the inclined surface 23a. A connection part 37 as the rest of the second conductor pattern 32 thus pushed in is electrically connected to the land 34.

Description

  The present invention relates to a multilayer substrate in which wirings are arranged in multiple layers with respect to an insulating base formed using a synthetic resin, and a method for manufacturing the same.

  Conventionally, a first substrate and a second substrate formed using a synthetic resin are bonded to each other, and the first wiring formed on one surface of the first substrate and the first substrate in the second substrate As a multilayer substrate formed by electrically connecting the second wiring formed on one surface opposite to the adhesive surface with the interlayer connection portion in the via hole formed in the second base material, and a manufacturing method thereof, for example, The thing of patent document 1 is known.

  In Patent Document 1, first, a thermoplastic resin film (corresponding to the second base material) having a metal foil attached on one side is prepared, and the metal foil is patterned by etching to form a conductor pattern. And a laser beam is irradiated to a 2nd base material by making a conductor pattern into a bottom part, and a via hole is formed. At this time, the conductor pattern constituting the second wiring is formed so that a part thereof is cantilevered (projects into the via hole) on the via hole.

  In addition, a thermoplastic resin film (corresponding to the first base material) having a conductor pattern (corresponding to the first wiring) on one side is separately prepared, and the conductor pattern forming surface on the first base material and the second base material The first base material and the second base material are laminated so that the surface opposite to the surface on which the conductor pattern is formed is a laminate. And this laminated body is heated with a hot press machine, pressurizing from the upper and lower sides of the lamination direction.

  At this time, the buffer material interposed between the heating press and the second base material enters the via hole, and the portion located on the via hole in the conductor pattern constituting the second wiring is pressed downward, It contacts the conductor pattern (the land of the first wiring) of the first base material. In this abutting state, the conductive paste is filled in the via hole by screen printing and heated to electrically connect the second wiring and the first wiring by the interlayer connection portion formed by sintering the conductive paste. To do.

  As described above, in Patent Document 1, a part of the conductor pattern constituting the second wiring is pushed into the via hole and brought into contact with the land of the first wiring. The conductive paste constituting the connection portion is easily spread in the via hole. As a result, voids are prevented from remaining in the via hole.

JP 2004-31778 A

  As described above, in the manufacturing method described in Patent Document 1, as a process excluding the preparation of the first base material having the first wiring, 1) formation of a conductor pattern constituting the second wiring by etching, and 2) second 2) Formation of via holes in the base material, 3) Integration of the first base material and the second base material and pressing of the conductor pattern into the via hole by pressurization and heating, 4) Filling the via hole with conductive paste, 5) A step of sintering the conductive paste (forming an interlayer connection) is necessary. As described above, according to the manufacturing method of Patent Document 1, the number of steps required for bonding the first base material and the second base material to each other and electrically connecting the first wiring and the second wiring is large. . Moreover, the equipment according to the number of processes is also required.

  Moreover, in patent document 1, when forming a conductor pattern (2nd wiring) in a 2nd base material, metal foil is patterned by an etching. That is, a conductor pattern is formed by a wet process. On the other hand, when forming a via hole in the second substrate, the via hole is formed by irradiating a laser beam. That is, a via hole is formed by a dry process. In addition, adhesion | attachment (pressurization and heating) with a 1st base material and a 2nd base material is also performed by a dry process. Thus, the wet process and the dry process are mixed, and the manufacturing process is complicated.

  In view of the above problems, an object of the present invention is to provide a method for manufacturing a multilayer substrate and a multilayer substrate that can be formed at low cost by simplifying the manufacturing process.

In order to achieve the above object, the invention described in claim 1
The first base material and the second base material formed using the synthetic resin are bonded to each other, and the first wiring formed on one surface of the first base material and the first base material in the second base material A method for producing a multilayer substrate in which a second wiring formed on one surface opposite to an adhesive surface is electrically connected by an interlayer connection portion disposed in a via hole of a second base material,
Forming a second base material having a via hole on one surface of the first base material having the first wiring so that the land of the first wiring is adhered to the first base material and the land of the first wiring is exposed from the via hole; 2 substrate forming step,
A metal foil is punched into a predetermined shape by hot pressing to form a conductor pattern, and a part of the conductor pattern is thermocompression bonded to one surface of the second substrate to form a second wiring, and the remainder of the conductor pattern is placed in the via hole. A heat press for pressing and pressing a part of the pressed conductor pattern along the wall surface of the via hole to be thermocompression bonded to the wall surface to form an interlayer connection portion, and electrically connecting the remainder of the pressed conductor pattern to the land of the first wiring A process,
In the second base material forming step, the portion of the wall surface of the via hole that is thermocompression-bonded of the conductor pattern that forms the interlayer connection portion is further away from the land of the first wiring in the stacking direction of the first wiring and the second wiring. The second base material is formed so as to have an inclination away from the exposed portion of the land of the first wiring in a direction perpendicular to the stacking direction.

  In the present invention, in order to form the second substrate so that the portion of the wall surface of the via hole where the conductor pattern forming the interlayer connection portion is thermocompression-bonded has the above inclination, the conductor is formed by punching the metal foil by hot pressing. This conductor pattern can be thermocompression bonded to the wall surface of the via hole while forming the pattern.

  Further, the metal foil is punched out by hot pressing to form a conductor pattern constituting the second wiring, and the portion of the second wiring in the conductor pattern is crimped to the surface of the second base material softened by heating (thermocompression bonding). ) Also, a part of the conductor pattern formed by punching is pushed into the via hole by a press die, and the part of the conductor pattern pushed into the via hole is heated on the wall surface of the via hole softened by heating (the surface of the second base material). Crimp. Furthermore, a part of the conductor pattern pushed into the via hole is electrically connected to the land of the first wiring by heating and pressing. In this way, the conductor pattern is pushed into the via hole while the conductor pattern constituting the second wiring is formed in one process (heat press process), and the first wiring and the second wiring are electrically connected. be able to. For this reason, a manufacturing process can be simplified compared with the past.

  Further, the second wiring and the first wiring are electrically connected while forming the second wiring by hot pressing. Therefore, the first wiring and the second wiring can be electrically connected to each other while the second base material having the second wiring is formed on the first base material having the first wiring only by the dry process. . Thereby, a manufacturing process can be simplified compared with the structure containing a wet process like the past.

  As described above, according to the present invention, the manufacturing process of the multilayer substrate can be simplified and the multilayer substrate can be formed at a low cost.

  According to a second aspect of the present invention, in the hot pressing step, it is preferable that the conductor pattern is thermocompression bonded to the land of the first wiring. In this way, when the conductor pattern constituting the second wiring and the land of the first wiring are thermocompression-bonded (diffusion-bonded), the conductor pattern and the first wiring are directly connected, thereby simplifying the manufacturing process. can do.

  According to a third aspect of the present invention, it is preferable to perform the hot pressing step in a state where the land of the first wiring is irradiated with plasma and the surface of the land is activated. This facilitates thermocompression bonding. Even if a plasma irradiation step is added, the manufacturing process can be simplified as compared with the conventional case.

  5. A welding step of welding the conductor pattern and the land of the first wiring by irradiating a laser beam onto the thermocompression bonding portion of the conductor pattern and the land of the first wiring after the hot pressing step. May be provided. According to this, connection reliability can be improved compared with the structure which electrically connects a conductor pattern and the land of 1st wiring only by thermocompression bonding. In addition, even if a welding process is added, a manufacturing process can be simplified compared with the past.

As described in claim 5, after the second substrate forming step, a paste containing metal particles is disposed on the land of the first wiring,
In the hot pressing step, the metal particles may be sintered by hot pressing to electrically connect the conductor pattern and the land of the first wiring.

  In this case, although the paste placement process is increased, the manufacturing process can be simplified as compared with the prior art even if this paste placement process is added.

  According to a sixth aspect of the present invention, in the second base material forming step, the second base material is formed into the first base material by injection molding using a thermoplastic resin using the first base material having the first wiring as an insert part. It is good to form on one side.

  According to this, a manufacturing process is compared with the 2nd base-material formation process compared with the structure provided with the process of preparing the 2nd base material which has a via hole, and the process of adhere | attaching this 2nd base material to a 1st base material. It can be further simplified. In addition, even if a 2nd base material formation process is provided with an above-described preparation process and an adhesion process, a manufacturing process can be simplified compared with the past.

  As described in claim 7, before the second base material forming step, the metal foil is punched into a predetermined shape by hot pressing to form the first wiring, and the first wiring is formed on one surface of the first base material. It is good to provide the 1st base material formation process of making it thermocompression-bond and form the 1st base material which has the 1st wiring. According to this, since the first wiring is also formed in the dry process, the multilayer substrate can be formed only in the dry process. Therefore, the manufacturing process can be further simplified.

Next, the invention according to claim 8 is:
An insulating base formed using a synthetic resin;
Wiring arranged in multiple layers on the insulating substrate;
An interlayer connection part disposed on an insulating base material and electrically connecting the first wiring and the second wiring located in the adjacent layer as wiring;
The second wiring is configured as a part of a conductor pattern formed by patterning a metal foil,
The conductor pattern integrally has the second wiring, the interlayer connection portion, and the connection portion electrically connected to the land of the first wiring by thermocompression bonding,
Of the conductor pattern, the portion of the second wiring and the interlayer connection portion is roughened on the surface of the first wiring side, and is thermocompression bonded to the insulating substrate.
The interlayer connection portion of the conductor pattern is inclined so as to move away from the connection portion of the conductor pattern in the direction perpendicular to the lamination direction as it is farther from the land of the first wiring in the lamination direction of the wiring arranged in multiple layers. It is characterized by.

  The multilayer substrate having such a structure is formed by the manufacturing method according to claim 2 described above. That is, the same effect as that of the first and second aspects of the invention can be achieved.

When forming a via hole that irradiates a laser beam to form the bottom of the conductor pattern as in the prior art, for example, a via hole is formed in an insulating substrate by a CO ₂ laser, and then smear (residue) is removed by a UV laser. It will be. The surface of the conductor pattern on the side irradiated with the laser beam is roughened in advance to improve the adhesion to the insulating substrate, but the portion on the via hole (irradiated with the laser beam) is irradiated with the laser beam. Part) is flattened. For this reason, the adhesiveness with an insulating base material etc. falls in the part irradiated with the laser beam. On the other hand, in this invention, the conductor pattern which stamped metal foil is thermocompression-bonded with respect to the 2nd base material which has a via hole by hot press. Therefore, it is not necessary to irradiate the surface on the first wiring side with laser light for forming a via hole. For this reason, the part of the 2nd wiring and interlayer connection part remains in the state by which the surface by the side of the 1st wiring was roughened among conductor patterns, and it can adhere to an insulating substrate favorably.

  According to a ninth aspect of the present invention, the conductor pattern may include a second wiring at each end thereof and an interlayer connection portion between each second wiring and the connection portion. According to this, the freedom degree of arrangement | positioning of the wiring containing an interlayer connection part can be improved compared with the structure which has a 2nd wiring in one end and has a connection part in the other end.

It is a top view top view showing a schematic structure of a multilayer substrate concerning a 1st embodiment. As for the conductor pattern and the via hole, only the area A surrounded by the two-dot chain line is shown for convenience. Further, the inner layer conductor pattern is also shown by a broken line. It is sectional drawing which follows the II-II line | wire of FIG. FIGS. 3A and 3B are cross-sectional views illustrating a method for manufacturing the multilayer substrate shown in FIG. 2, wherein FIG. 3A is a first base material preparation step having a first conductor pattern, FIG. 2B is a second base material formation step having a via hole; ) A hot press process is shown. It is sectional drawing which shows the modification of a manufacturing method, and shows the pre-processing process by plasma irradiation. It is sectional drawing which shows the modification of a manufacturing method, and shows the welding process by a laser beam. It is sectional drawing, the manufacturing method of the multilayer substrate which concerns on 2nd Embodiment, (a) shows a paste application | coating process, (b) shows a hot press process. It is sectional drawing which shows schematic structure of the multilayer substrate concerning 3rd Embodiment. It is sectional drawing which shows the other modification of a multilayer substrate. It is sectional drawing which shows the other modification of a multilayer substrate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings shown below, common or related elements are given the same reference numerals. Further, the stacking direction of the wirings arranged in multiple layers, in other words, the thickness direction of the insulating base material is simply referred to as the stacking direction. A direction perpendicular to the stacking direction is simply referred to as a vertical direction.

(First embodiment)
A multilayer substrate 10 shown in FIGS. 1 and 2 includes an insulating base 20 formed using a synthetic resin, wirings 33 and 35 arranged in multiple layers with respect to the insulating base 20, and an insulating base 20. And an interlayer connection part 36 for electrically connecting the wirings 33 and 35 located in adjacent layers. In the present embodiment, as an example, the multilayer substrate 10 includes two layers of wirings 33 and 35.

  The insulating base material 20 includes at least a synthetic resin as a constituent material. As the synthetic resin, any of a thermoplastic resin and a thermosetting resin can be employed, but a thermoplastic resin is more preferable in consideration of moldability described later and adhesiveness with the conductor pattern 30. It is preferable to adopt the one that does not flow largely as a whole, but softens the surface (the one that allows the conductor patterns 31 and 32 to adhere) under the pressurizing and heating conditions of a hot press described later.

  In this embodiment, the two base materials 21 and 22 of the 1st base material 21 and the 2nd base material 22 which consist of thermoplastic resins are mutually adhere | attached, and the insulating base material 20 is comprised. As the thermoplastic resin, PBT, PPS, or the like can be used. As resin materials constituting the two base materials 21 and 22, different materials can be adopted, but the same material is preferably adopted. Also in this embodiment, the two base materials 21 and 22 are formed using the same thermoplastic resin.

  Of the two base materials 21 and 22, the first base material 21 is formed in a flat rectangular plate having a predetermined thickness. And the 1st conductor pattern 31 which comprises the 1st wiring 33 is being fixed to the one surface 21a of the 1st base material 21. FIG. On the other hand, the second base material 22 is bonded and fixed to the one surface 21 a of the first base material 21, and its outer contour coincides with the first base material 21 so as to cover the one surface 21 a of the first base material 21. Yes. In addition, the second base material 22 is formed with a via hole 23 for arranging an interlayer connection portion 36 that electrically connects the first wiring 33 and the second wiring 35. The second conductor pattern 32 constituting the second wiring 35 is fixed to the second base material 22.

  The via hole 23 penetrates through the second base material 22 and opens on one surface 22b of the second base material 22 opposite to the bonding surface 22a with the first base material 21. Of the wall surface of the via hole 23, the surface 23 a to which the conductor pattern 32 forming the interlayer connection portion 36 is thermocompression bonded is the first in the vertical direction as the distance from the first conductor pattern 31 (land 34) increases in the stacking direction. The conductor pattern 31 has an inclination away from the exposed portion of the land 34. Hereinafter, the surface 23a is referred to as an inclined surface 23a. The exposed portion of the land 34 is a portion of the land 34 that is located in the via hole 23. In the present embodiment, the via hole 23 has a quadrangular frustum shape, and an inclined shape other than the inclined surface 23a to which the conductor pattern 32 is thermocompression bonded is also formed. That is, the opening area of the via hole 23 increases as the distance from the first conductor pattern 31 increases in the stacking direction. Further, the amount of change in the opening area per unit length of the via hole 23 is constant in the stacking direction.

  As described above, the multilayer substrate 10 has the conductor patterns 30 (31, 32) constituting the wirings 33, 35 in multiple layers. Among the conductor patterns 30, the first conductor pattern 31 formed on the one surface 21 a of the first base material 21 includes a land 34 provided for electrical connection between the first wiring 33 and the second wiring 35, have. It can be said that the land 34 is a portion of the first wiring 33 that is used for electrical connection with the second wiring 35. The first wiring 33 is an inner layer wiring disposed inside the insulating base material 20, and a part of the land 34 is exposed to the outside through the via hole 23.

  The configuration of the first conductor pattern 31 is not particularly limited. In the present embodiment, a first conductor pattern 31 formed by punching a metal foil is employed, and the first conductor pattern 31 is fixed to one surface 21a of the first base material 21 made of a thermoplastic resin by thermocompression bonding. ing. The first conductor pattern 31 is in a state where the surface on the first base material 21 side is roughened and the surface on the opposite side to the first base material 21 is not roughened.

  On the other hand, the second conductor pattern 32 includes a second wiring 35 formed on the one surface 22b of the second base material 22, an interlayer connection portion 36 that electrically connects the first wiring 33 and the second wiring 35, and a second wiring pattern 35. And a connection portion 37 that is electrically connected to the exposed portion of the land 34 of the one conductor pattern 31. In the second conductor pattern 32, the surface 32a on the second base material 22 side (the first conductor pattern 31 side) is roughened, and the surface opposite to the second base material 22 is not roughened. It has become.

  The interlayer connection portion 36 connects the second wiring 35 and the connection portion 37 in the second conductor pattern 32, and the inclined surface along the inclined surface 23 a of the via hole 23 formed in the second base material 22. It is fixed to 23a by thermocompression bonding. That is, the interlayer connection part 36 is connected to the connection part 37 (in other words, the exposed part of the land 34) in the vertical direction as the distance from the first conductor parane 31 (land 34) in the stacking direction with respect to the second substrate 2. It is inclined to move away from.

  The connection portion 37 is disposed to face the exposed portion of the land 34 of the first conductor pattern 31, and the second conductor pattern 32 is electrically connected to the first conductor pattern 31 at the connection portion 37. . In the present embodiment, the connection portion 37 is fixed (electrically and mechanically connected) to the exposed portion of the land 34 by thermocompression bonding. In other words, diffusion bonding occurs at the interface between the connection portion 37 and the exposed portion of the land 34, whereby the first conductor pattern 31 and the second conductor pattern 32 (the first wiring 33 and the second wiring 35) are electrically connected. Has been.

  Next, a method for manufacturing the multilayer substrate 10 configured as described above will be described with reference to FIGS.

  First, as shown to Fig.3 (a), the 1st base material 21 which has the 1st conductor pattern 31 (1st wiring 33) is prepared. In the present embodiment, a metal foil 24 (copper foil) having a thickness of 18 μm, for example, is disposed on one surface 21 a of the separately prepared first base material 21, and the first base material 21 is held by the lower mold 100. In this state, the upper die 101 is lowered, and the metal foil 24 is punched out by the convex portion 102 of the upper die 101. At this time, at least one of the molds 100 and 101 (the upper mold 101 in the present embodiment) is heated by a heater or the like (not shown), and the surface of the first base material 21 is softened by this heat. Therefore, the punched metal foil 24, that is, the first conductor pattern 31 is pressed into the one surface 21 a of the first base material 21 and welded (thermocompression bonding). In this manner, the metal foil 24 is punched out by the upper mold 101 and thermocompression bonded to form the first conductor pattern 31 on the first base material 21. In addition, since parts other than the convex part 102 among metal foil 24 are not pushed in by the upper mold | type 101, but remain as shown to Fig.3 (a), they can be removed after mold opening. The above corresponds to the preparation step of the first base material 21 described in the claims.

  Next, as shown in FIG. 3B, the second base material 22 having the via hole 23 is formed on the one surface 21 a of the first base material 21. In the present embodiment, the second base material 22 is formed on the one surface 21a of the first base material 21 by injection molding using a thermoplastic resin using the first base material 21 having the first conductor pattern 31 as an insert part. . For this reason, the second base material 22 is formed in the shape having the via hole 23 along the shape of a mold (not shown) and is bonded and fixed to the first base material 21. The above corresponds to the second substrate forming step described in the claims.

  Next, as shown in FIG. 3C, the second conductor pattern 32 is formed and fixed to the second base material 22, and the formed second conductor pattern 32 is electrically connected to the first conductor pattern 31. . In this step, similarly to the preparation of the first base material 21 having the first conductor pattern 31 (first wiring 33), the hot pressing is performed. For example, a metal foil 25 (copper foil) having a thickness of 18 μm is disposed on one surface 22 b of the second base material 22 so as to close the via hole 23, and the upper mold 111 is held with the first base material 21 held by the lower mold 110. Is lowered, and the metal foil 25 is punched out by the convex portions 112 and 113 of the upper die 111. Of the protrusions 112 and 113, the first protrusion 112 punches out a portion corresponding to the second wiring 35, and the second protrusion 113 that protrudes further than the first protrusion 112 includes the interlayer connection 36 and This is a part for punching out a part corresponding to the connection part 37. The second convex portion 113 has an inclined surface 113 a corresponding to the inclined surface 23 a so that the interlayer connecting portion 36 is thermocompression bonded along the inclined surface 23 a of the via hole 23. Further, in order to thermocompress the connecting portion 37 to the land 34 of the first conductor pattern 31, the lower mold 110 has a front end surface 113 b parallel to the first base material mounting surface.

  At this time, at least one of the molds 110 and 111 (the upper mold 111 in this embodiment) is heated by a heater (not shown) or the like, and the surface of the second base material 22 is softened by this heat. Accordingly, in the punched metal foil 25, that is, the second conductor pattern 32, the second wiring 35 is pushed into the one surface 22 b of the second base material 22 by the first protrusion 112 of the upper mold 111 and is welded (heated). Crimp). Further, the portion of the second conductor pattern 32 excluding the second wiring 35 is pushed into the via hole 23 by the second convex portion 113 of the upper mold 111. Of the second conductor pattern 32, the interlayer connection portion 36 is pushed into the inclined surface 23a of the via hole 23 by the inclined surface 113a of the second convex portion 113 of the upper mold 111, and the inclined surface along the inclined surface 23a. 23a is welded (thermocompression bonding). Further, in the second conductor pattern 32, the connection portion 37 is pushed into the land 34 of the first conductor pattern 31 by the tip surface 113 b of the second convex portion 113 of the upper mold 111 and is thermocompression bonded to the land 34. That is, diffusion bonding is formed.

  In this manner, the metal foil 25 is punched and thermocompression bonded with the upper mold 111 to form the second conductor pattern 32 on the second base material 22, and the second conductor pattern 32 is electrically connected to the first conductor pattern 31. Connect to. In addition, portions other than the convex portions 112 and 113 in the metal foil 25 remain as shown in FIG. 3C without being pushed in by the upper die 111, and thus can be removed after the die is opened. The above corresponds to the hot pressing process described in the claims. In this way, the multilayer substrate 10 shown in FIGS. 1 and 2 can be formed.

  Next, the effects of the features of the multilayer substrate 10 and the manufacturing method thereof according to the present embodiment will be described.

  In the present embodiment, of the wall surface of the via hole 23, the portion 23a to which the interlayer connection portion 36 of the second conductor pattern 32 is thermocompression bonded is defined as the inclined surface described above. Accordingly, the second conductive pattern 32 can be thermocompression bonded to the wall surface of the via hole 23 while the second conductive pattern 32 is formed by punching the metal foil 25 by hot pressing.

  Further, the metal foil 25 is punched out by hot pressing to form the second conductor pattern 32, and the second wiring 35 in the second conductor pattern 32 is crimped to the one surface 22b of the second base material 22 softened by heating ( Thermocompression). Further, the portion of the second conductor pattern 32 excluding the second wiring 35 is pushed into the via hole 23 by the second convex portion 113 of the upper mold 111, and the interlayer connection portion 36 of the second conductor pattern 32 is softened by heating. And thermocompression-bonded to the inclined surface 23a. Further, the connection portion 37 of the second conductor pattern 32 is thermocompression bonded to the land 34 of the first conductor pattern 31. As described above, a part of the second conductor pattern 32 is pushed into the via hole 23 while forming the second conductor pattern 32 constituting the second wiring 35 in one process (heat press process), and the first conductor pattern 32 is formed. The wiring 33 and the second wiring 35 can be electrically connected. For this reason, a manufacturing process can be simplified compared with the past. Specifically, according to the present embodiment, as a process excluding the preparation of the first base material 21 having the first wiring 33, 1) formation of the second base material 22 having the via hole 23 and adhesion to the first base material 21 Step 2) Only the two steps of forming the second conductor pattern 32 by hot pressing, bonding to the second base material 22, and electrically connecting the wirings 33 and 35 are sufficient. For this reason, compared with the conventional manufacturing method described in [Problems to be Solved by the Invention], the number of manufacturing steps can be greatly reduced.

  Further, the second conductor pattern 32 (second wiring 35) and the first conductor pattern 31 (first wiring 33) are electrically connected while forming the second conductor pattern 32 (second wiring 35) by hot pressing. I do. Accordingly, the first substrate 33 having the first wiring 33 and the second substrate 35 having the second wiring 35 are formed on the first substrate 21 having the first wiring 33 only by a dry process. Connection can be made. Thereby, a manufacturing process can be simplified compared with the structure containing a wet process like the past.

  As described above, according to the present embodiment, the manufacturing process of the multilayer substrate 10 can be simplified and the multilayer substrate 10 can be formed at low cost.

By the way, when a via hole having a conductor pattern as a bottom is formed by irradiating a laser beam as in the prior art, for example, a via hole is formed in an insulating substrate with a CO ₂ laser, and then smear (residue) is removed with a UV laser. It will be removed. The surface of the conductor pattern on the side irradiated with the laser beam is roughened in advance to improve the adhesion to the insulating substrate, but the portion on the via hole is flattened by the irradiation of the laser beam. For this reason, the adhesiveness with an insulating base material etc. falls in the part irradiated with the laser beam. On the other hand, in this embodiment, the second conductor pattern 32 formed by punching the metal foil 25 is thermocompression bonded to the second base material 22 having the via hole 23 by hot pressing. Therefore, it is not necessary to irradiate the surface 32a of the second conductor pattern 32 on the first conductor pattern 31 side with the laser beam for forming the via hole 23. For this reason, in the second conductor pattern 32, the portions of the second wiring 35 and the interlayer connection portion 36 remain in a state where the surface on the first conductor pattern 31 side is roughened, which is favorable with respect to the second base material 22 Can be glued to.

  In the present embodiment, the first base material 21 having the first conductor pattern 31 (first wiring 33) is used as an insert part, and the second base material 22 is formed by injection molding using a thermoplastic resin. 21 is formed on one surface 21a. That is, the formation of the second base material 22 and the adhesion between the first base material 21 and the second base material 22 are performed simultaneously. Therefore, the second base material forming step is a manufacturing process as compared with a configuration including a step of preparing the second base material 22 having the via hole 23 and a step of bonding the second base material 22 to the first base material 21. Can be further simplified.

  In the present embodiment, in the preparation process of the first base material 21, the metal foil 24 is punched into a predetermined shape by hot pressing to form the first conductor pattern 31 (first wiring 33), and the first base material 21 The first substrate 21 having the first conductor pattern 31 is formed by thermocompression bonding the first conductor pattern 31 on the one surface 21 a of the substrate 21. According to this, since the first base material 21 is prepared in the dry process, the entire multilayer substrate 10 can be formed only in the dry process. Therefore, the manufacturing process can be further simplified.

(Modification)
In the present embodiment, in the second base material forming step, the first base material 21 having the first conductor pattern 31 (first wiring 33) is used as an insert part, and the second base material is formed by injection molding using a thermoplastic resin. The example which forms 22 on the one surface 21a of the 1st base material 21 was shown. However, the second base material forming step may include a step of preparing the second base material 22 having the via holes 23 and a step of bonding the second base material 22 to the first base material 21. Specifically, the via hole 23 of the second base material 22 is formed by laser processing, drilling, or the like, and then heated, for example, while being pressurized, so that the second base material 22 and the first base material 21 having the via hole 23 are formed. Are glued together. In this case, although the number of manufacturing steps is increased as compared with the above embodiment, the number of manufacturing steps can be reduced as compared with the conventional case. In addition, as the 2nd base material 22, not only a thermoplastic resin but the thermosetting resin of a B stage state can also be employ | adopted.

  In this embodiment, the example which forms the 1st conductor pattern 31 also by hot press was shown. However, the formation method of the 1st conductor pattern 31 is not limited to the example shown in the said embodiment. For example, the conductive foil may be formed by etching, plating, screen printing using a conductive paste, or the like. In this case, although the number of manufacturing steps is increased as compared with the above embodiment, the number of manufacturing steps can be reduced as compared with the conventional case. In addition, as a constituent material of the 1st base material 21, it is not limited to a thermoplastic resin, A thermosetting resin can also be employ | adopted.

  Also, as shown in FIG. 4, before the hot pressing process, the plasma 121 from the plasma source 120 is formed on the exposed portion of the land 34 of the first conductor pattern 31 (the gas is turned into plasma to at least contain radicals). May be activated to activate the surface of the land 34, and in this state, a hot pressing process may be performed. According to this, the connecting portion 37 of the second conductor pattern 32 can be easily thermocompression bonded to the land 34 of the first conductor pattern 31. In other words, it becomes easy to form diffusion bonding. Thereby, the electrical connection reliability of the 1st conductor pattern 31 and the 2nd conductor pattern 32 can be improved. Even if this plasma irradiation step is added, the manufacturing process can be simplified as compared with the conventional case. Either atmospheric pressure plasma or vacuum plasma can be employed. Moreover, as gas, inert gas, such as Ar, He, and Xe, a carbon dioxide, nitrogen, etc. are employable.

  Further, after the hot pressing step, as shown in FIG. 5, the laser light 131 is irradiated from the light source 130 to the thermocompression bonding portion between the connection portion 37 of the second conductor pattern 32 and the land 34 of the first conductor pattern 31. The connecting portion 37 and the land 34 may be welded. According to this, connection reliability can be improved compared with the structure which connects the connection part 37 and the land 34 only by thermocompression bonding. In addition, even if a welding process is added, a manufacturing process can be simplified compared with the past.

(Second Embodiment)
In the present embodiment, the description of the parts common to the multilayer substrate 10 and the manufacturing method thereof shown in the first embodiment is omitted. In the first embodiment, in the hot pressing process, the first wiring 33 and the second wiring 35 are electrically connected by thermocompression bonding to the connection portion 37 of the second conductor pattern 32 and the land 34 of the first conductor pattern 31. An example of connection is shown.

  On the other hand, in this embodiment, after the formation of the second base material 22 shown in the first embodiment, as shown in FIG. 6A, on the land 34 of the first conductor pattern 31 exposed from the via hole 23. A paste 38 containing metal particles is disposed.

  The paste 38 is formed by dispersing any one of single metal particles, a plurality of metal particles, and composite metal particles in a solvent. The plurality of metal particles refers to containing a plurality of metal particles such as Ag particles and Sn particles, and the composite metal particle refers to alloy particles such as AgSn particles. As this metal particle, what is sintered by the pressurization and heating conditions of a hot press is employ | adopted. For example, low melting point metal particles may be employed. Moreover, it is preferable to employ | adopt what has a small average particle diameter. In the present embodiment, metal particles having an average particle size of nano-order and coated with an organic protective film are employed. Such a paste 38 can be locally disposed on the land 34 using, for example, an inkjet method.

  And after arrange | positioning the paste 38, as shown in FIG.6 (b), the hot press process similar to 1st Embodiment is performed. In this hot press process, the paste 38 is pressed by the upper mold 111 through the connection portion 37 of the second conductor pattern 32, and heat is transmitted from the upper mold 111 to the paste 38 through the connection portion 37, for example. . As a result, the solvent in the paste 38 is vaporized, and the metal particles are sintered to form the joining member 39. Then, the connecting portion 37 of the second conductor pattern 32 and the land 34 of the first conductor pattern 31 are electrically connected via the bonding member 39.

  According to this embodiment, the same effect as that of the first embodiment can be obtained. In addition, although the process of paste arrangement | positioning will increase compared with 1st Embodiment (refer FIG. 3), even if this paste arrangement | positioning process is added, a manufacturing process can be simplified compared with the past.

(Third embodiment)
In the present embodiment, the description of the parts common to the multilayer substrate 10 and the manufacturing method thereof shown in the above embodiment is omitted. In the above embodiment, the second conductor pattern 32 has the second wiring 35 at one end, the connection portion 37 at the other end, and the interlayer connection portion 36 between the second wiring 35 and the connection portion 37. An example is shown.

  On the other hand, in the present embodiment, as shown in FIG. 7, the second conductor pattern 32 has second wirings 35 at both ends thereof, and an interlayer connection between each second wiring 35 and the connection portion 37. Each has a portion 36.

  When such a configuration is adopted as the second conductor pattern 32, the degree of freedom in wiring design in the multilayer substrate 10 is improved as compared with a configuration having the second wiring 35 at one end and the connecting portion 37 at the other end. Can do. Note that the second wiring 35 may include a land 40 described later.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In the above embodiment, an example of the two-layer wiring is shown as the multilayer substrate 10. However, the number of wiring layers is not limited to two, and may be three or more. For example, in the example shown in FIG. 8, the multilayer substrate 10 has three-layer wiring. In FIG. 8, the multilayer substrate 10 shown in FIG. 2 is used as the first base material described in the claims, and the second conductor pattern 32 (second wiring 35) is used as the first wiring described in the claims. The third base material 26 having the third conductor pattern 41 is disposed on the multilayer substrate 10. That is, the third substrate 26 corresponds to the second substrate described in the claims, and the third conductor pattern corresponds to the conductor pattern having the second wiring described in the claims. Therefore, the third base material 26 is formed by the method of the second base material forming step described above, and the third conductor pattern 41 is formed by the method of the hot press step described above. 8 is a land to which the third conductor pattern 41 of the second wiring 35 is connected in the second conductor pattern 32, and reference numeral 42 is thermocompression-bonded to the one surface 26 a of the third base material 26. The third wiring, reference numeral 43 is an interlayer connection portion that is thermocompression bonded to the inclined surface 23 a of the via hole 23 formed in the third base material 26, and reference numeral 44 is electrically connected to the land 40 of the second conductor pattern 32. Connected portion. Further, the surface 41a on the third base material 26 side in the third conductor pattern 41 is roughened.

  In the said embodiment, the 2nd conductor pattern 32, the via hole 23, a part of land 34 of the 1st conductor pattern 31, and the one surface 22b of the 2nd base material 22 showed the example exposed outside. However, for example, as shown in FIG. 9, a cover base material 27 is provided on one surface 22 b of the second base material 22, and the second conductor is passed through an external connection opening 28 formed in the cover base material 27. Of the pattern 32, only the land 40 of the second wiring 35 may be exposed to the outside. Note that the cover base 27 is formed by injection molding using a thermoplastic resin, transfer molding using a thermosetting resin, and attaching a film made of a thermosetting resin or a thermosetting resin in a B-stage state. It can be formed on one surface 22b of the substrate 22.

  In the above embodiment, an example in which the via hole 23 has a square frustum shape is shown. However, the shape of the via hole 23 is that the surface of the second conductor pattern 32 to which the interlayer connection portion 36 is thermocompression-bonded becomes farther away from the land 34 of the first conductor pattern 31 in the stacking direction. Any material having an inclination away from the exposed portion may be used. For example, a truncated cone shape or a truncated pyramid shape other than a quadrangular pyramid may be used. Further, in the truncated pyramid shape, only the surface to which the interlayer connection portion 36 of the second conductor pattern 32 is thermocompression bonded may be inclined, and the other surface may be parallel to the stacking direction.

DESCRIPTION OF SYMBOLS 10 ... Multilayer substrate 20 ... Insulating base material 21 ... 1st base material 22 ... 2nd base material 23 ... Via hole 23a ... Inclined surface 24, 25 ... Metal foil 31 .... First conductor pattern 32 ... second conductor pattern 33 ... first wiring 34 ... land 35 ... second wiring 36 ... interlayer connection part 37 ... connection part 110 ... Lower mold 111 ... Upper mold 112 ... First convex part 113 ... Second convex part

Claims (9)

The first base material and the second base material formed using a synthetic resin are bonded to each other, and the first wiring formed on one surface of the first base material and the first base material in the second base material And a second wiring formed on one surface opposite to the adhesion surface of the second substrate by electrical connection by an interlayer connection portion disposed in the via hole of the second base material. ,
A second substrate having the via hole on one surface of the first substrate having the first wiring so that the land of the first wiring adheres to the first substrate and the land of the first wiring is exposed from the via hole. A second base material forming step of forming a material;
While forming a conductor pattern by punching a metal foil into a predetermined shape by hot pressing, a part of the conductor pattern is thermocompression bonded to one surface of the second base material to form the second wiring, and the rest of the conductor pattern is The conductor pattern is pushed into the via hole, a part of the pushed conductor pattern is thermocompression bonded to the wall surface along the wall surface of the via hole to form the interlayer connection portion, and the remainder of the pushed conductor pattern is used as the land of the first wiring. A hot press process for electrical connection,
In the second base material forming step, a portion of the wall surface of the via hole that is thermocompression-bonded of the conductor pattern that forms the interlayer connection portion is the first wiring in the stacking direction of the first wiring and the second wiring. The second substrate is formed so as to be inclined away from the exposed portion of the land of the first wiring in a direction perpendicular to the stacking direction as the distance from the land is increased. .   The method for manufacturing a multilayer substrate according to claim 1, wherein, in the hot pressing step, the conductor pattern is thermocompression bonded to a land of the first wiring.   3. The method of manufacturing a multilayer substrate according to claim 2, wherein the heat pressing step is performed in a state where the land of the first wiring is irradiated with plasma and the surface of the land is activated.   After the heat pressing step, the method includes a welding step of irradiating the thermocompression bonding portion between the conductor pattern and the land of the first wiring with a laser beam to weld the conductor pattern and the land of the first wiring. The method for producing a multilayer substrate according to claim 2, wherein: After the second base material forming step, a paste containing metal particles is disposed on the land of the first wiring,
2. The multilayer substrate according to claim 1, wherein in the hot pressing step, the metal particles are sintered by hot pressing to electrically connect the conductor pattern and the land of the first wiring. Production method.   In the second substrate forming step, the second substrate is formed on one surface of the first substrate by injection molding using a thermoplastic resin using the first substrate having the first wiring as an insert part. The method for producing a multilayer substrate according to any one of claims 1 to 5, wherein:   Before the second substrate forming step, by hot pressing, the metal foil is punched into a predetermined shape to form the first wiring, and the first wiring is thermocompression bonded to one surface of the first substrate, The manufacturing method of the multilayer substrate according to claim 1, further comprising a first base material forming step of forming a first base material having the first wiring. An insulating base formed using a synthetic resin;
Wiring arranged in multiple layers on the insulating substrate;
An interlayer connection part disposed on the insulating base material and electrically connecting the first wiring and the second wiring located in an adjacent layer as the wiring;
The second wiring is configured as a part of a conductor pattern formed by patterning a metal foil,
The conductor pattern integrally includes the second wiring, the interlayer connection portion, and a connection portion electrically connected to the land of the first wiring by thermocompression bonding,
Of the conductor pattern, the surface of the first wiring side in the second wiring and the interlayer connection portion is roughened, and is thermocompression bonded to the insulating substrate,
The interlayer connection part of the conductor pattern is inclined so as to move away from the connection part of the conductor pattern in the direction perpendicular to the lamination direction as it is farther from the land of the first wiring in the lamination direction of the wirings arranged in multiple layers. A multilayer substrate characterized by the above.   The multilayer substrate according to claim 8, wherein the conductor pattern has the second wiring at both ends thereof, and the interlayer connection portion between each second wiring and the connection portion.

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