WO2013021477A1

WO2013021477A1 - Circuit substrate manufacturing method

Info

Publication number: WO2013021477A1
Application number: PCT/JP2011/068243
Authority: WO
Inventors: 秀吉瀧井; 典明種子; 高木　剛
Original assignee: 株式会社メイコー
Priority date: 2011-08-10
Filing date: 2011-08-10
Publication date: 2013-02-14
Also published as: TW201320849A

Abstract

Provided is a circuit substrate manufacturing method, comprising: a preparation step of forming a first metal foil (8) upon a first support substrate (14), and forming a second metal foil (38) upon a second support substrate (36); a bump forming step of respectively forming metallic first and second bumps (21, 38) upon the first and second metal foils by plating; a layering step of placing the first bumps (21) and the second bumps (38) opposite one another to form columnar bodies (4), forming an insulation substrate (58) which is sandwiched between the first metal foil and the second metal foil and wherein the columnar bodies (4) are embedded, and forming a layered body (60) wherein the support substrates are respectively overlapped via the first and second metal foils on both sides of the insulation substrate; and a pattern forming step of detaching the first and second support substrates (14, 36) from the layered body (60), exposing the first and second metal foils (8, 38), and respectively forming the first and second metal foils in first and second wiring patterns (6, 62).

Description

Circuit board manufacturing method

The present invention relates to a circuit board manufacturing method, and more particularly to a circuit board manufacturing method having a heat dissipation path for heat dissipation.

High heat generation type circuit boards, such as circuit boards on which electrical or electronic components with a large amount of heat are mounted and circuit boards for large currents where large currents flow through the circuit, have a heat dissipation path that dissipates the generated heat. I have. This type of heat dissipation path generally includes a thermal via, which covers the through hole penetrating from one surface of the circuit board to the other surface and the inner wall surface of the through hole and the both surfaces of the circuit board. And a metal material connected to the wiring pattern. According to a circuit board including such a thermal via, for example, even if the component mounted on one surface of the circuit board generates heat, the heat is transmitted to the other surface of the circuit board through the thermal via. The heat is dissipated.

However, since the metal material forming the thermal via is only in the form of a thin layer formed only on the inner wall of the through hole, the heat transfer effect by the thermal via, that is, the heat radiation efficiency is relatively low. For this reason, when the calorific value of electronic parts etc. increases, there exists a problem that it cannot fully radiate.
Therefore, it can be considered that the through hole is filled with a metal paste to further improve the heat dissipation efficiency. As a means for filling the through hole with the metal paste, a technique of filling the through hole provided in the circuit board with the metal paste (for example, see Patent Document 1) is used.

The method of filling the through hole of the circuit board of Patent Document 1 with the metal paste is as follows.
First, through holes are provided in a circuit board having wiring patterns on both sides. Thereafter, a metal paste containing a required metal powder is prepared, and this metal paste is pushed into the through hole with a roll or a piston. At this time, by applying ultrasonic vibration to the circuit board at the same time, the metal paste can easily flow and the metal paste can easily enter the through hole. In this way, the metal paste is filled into the through hole.

JP-A-5-37157

By the way, as described above, filling the through hole of the circuit board with the metal paste is very time-consuming, has poor workability, and deteriorates the manufacturing efficiency of the circuit board. In addition, the metal paste may not be completely filled in the through holes, and the desired heat dissipation efficiency may not be obtained with certainty.

An object of the present invention is to provide a manufacturing method that enables rapid manufacture of a circuit board having a heat dissipation function without requiring a separate manufacturing process for securing only a heat dissipation path.

In the present invention, an insulating substrate, a first wiring pattern formed on one surface of the insulating substrate, a second wiring pattern formed on the other surface, and the first and first wiring patterns are provided in the insulating substrate. A circuit board manufacturing method comprising a heat radiation path made of a metal column that thermally connects two wiring patterns, wherein first and second supporting substrates are prepared, and the first supporting substrate is provided with the first supporting substrate. Forming a first metal foil on which a wiring pattern is to be formed, and forming a second metal foil on which a second wiring pattern is to be formed on a second carrier substrate; and on the first and second metal foils A bump forming step of forming metal first and second bumps each having a height approximately half the height of the columnar body by plating, and the first metal foil and the second metal foil to face each other. The first and second support substrates are arranged, and the columnar body Forming the insulating substrate sandwiched between the first metal foil and the second metal foil and having the columnar body embedded therein while the first bump and the second bump are abutted with each other to form And laminating the both sides of the insulating substrate with the first and second metal foils interposed therebetween to form a laminate, and peeling the first and second carrier substrates from the laminate. And a pattern forming step of forming the first and second metal foils on the first and second wiring patterns after exposing the first and second metal foils, respectively. A circuit board manufacturing method is provided.

Here, the laminating step is a plate-like main prepreg having one main through-hole into which the first and second bumps are to be inserted, and prepares a main prepreg containing uncured insulating resin, In order to insert the first and second bumps into the main through-holes of the main prepreg and to bring the tips of the first and second bumps into contact with each other, the first and second support substrates on both sides of the main prepreg After that, by pressing the first and second supporting substrates in a direction approaching each other, the first and second bumps are integrated to form the columnar body, and the main prepreg It is preferable to form the insulating substrate in which the columnar body is embedded by flowing the insulating resin.

Further, the bump forming step is a thick conductor for providing a thick wiring pattern thicker than the first wiring pattern by a formation method similar to the formation method of the first bump on the first metal foil. And the laminating step includes a main prepreg having a part of the main through hole and a remaining part of forming the main through hole in cooperation with the part of the main through hole. Sub-prepregs each having a main through-hole and a sub-through-hole into which the thick conductor is to be inserted, further comprising a sub-prepreg containing uncured insulating resin, for pressing the first and second supporting substrates Prior to disposing the first and second supporting substrates to sandwich the sub-prepreg and the main prepreg between the first metal foil and the second metal foil, It is preferable to insert the thick conductor sub through hole.

According to the present invention, the first and second bumps are brought into contact with each other through the main through hole of the prepreg to form a metal columnar body, thereby thermally radiating the first wiring pattern and the second wiring pattern. A route is secured. Since this heat dissipation path is not formed by a manufacturing process separately provided in the manufacturing process of the circuit board, rapid manufacturing of the entire circuit board can be realized. In addition, a heat radiation path having a desired diameter can be easily formed without being limited by the hole diameter, as compared with filling the through hole or the like with a metal paste. Further, compared with the case where the through hole is filled with a metal paste, the work efficiency due to the number of holes does not decrease.

Further, by providing the thick conductor separately from the first bump, the wiring pattern in the portion where the thick conductor exists can be partially thickened, and a large current can flow in this portion. As a result, the heat dissipation path can be easily secured even in the large current substrate. At this time, by using a sub-prepreg in which a sub through hole is formed at a position corresponding to the thick conductor, the stacking process can be easily and quickly performed.

It is the schematic which shows 1st Embodiment of the manufacturing method of the circuit board based on this invention in order. It is the schematic which shows the continuation of FIG. 1 in order. It is the schematic which shows 2nd Embodiment of the manufacturing method of the circuit board based on this invention in order. It is the schematic which shows the continuation of FIG. 3 in order.

(First embodiment)
With reference to FIG.1 and FIG.2, the manufacturing method of the circuit board 2 provided with the thermal radiation path | route which consists of the metal columnar bodies 4 which concern on this invention is demonstrated.
In the present invention, first and

second carrier substrates

14 and 36 are prepared, and the first metal foil 8 on which the first wiring pattern 6 is to be formed is formed on the first carrier substrate 14, while the second carrier substrate is formed. A second metal foil 38 on which the second wiring pattern 62 is to be formed is formed on 36 (preparation step).

In this step, first, as shown in FIG. 1A, a first carrier substrate 14 is prepared. The first carrier substrate 14 is a thin plate made of, for example, stainless steel. Then, as shown in FIG. 1B, a first metal foil 8 is formed on the first carrier substrate 14. The first metal foil 8 is made of, for example, a copper plating film obtained by electrolytic plating. Thus, the copper-clad steel plate 16 which consists of a stainless steel plate with one surface covered with copper foil is obtained. Here, in the first metal foil 8, a surface in contact with the first carrier substrate 14 is a first surface 18, and a surface opposite to the first surface 18 is a second surface 20.

Next, metal first and

second bumps

10 and 30 having substantially half the height of the columnar body 4 are formed on the first and

second metal foils

8 and 38 by plating (bump forming step), respectively.

In this step, first, metallic first bumps 10 are formed on the first metal foil 8 to be formed on the first wiring pattern 6 of the circuit board 2.

Specifically, as shown in FIG. 1C, the second surface 20 of the first metal foil 8 of the copper-clad steel plate 16 is covered with a plating resist 22 made of a dry film having a predetermined thickness. Thereafter, the plating resist 22 is provided with a bump formation hole 24 that reaches the second surface 20 of the first metal foil 8 at a predetermined position. Specifically, the bump formation hole 24 is a hole used for forming the first bump 10 to be a part of the heat dissipation path, and one opening end 23 is closed by the first metal foil 8, and the other The opening end 25 of the plating resist 22 is open to the exposed surface 34 opposite to the contact surface 35 of the plating resist 22 with the first metal foil 8. Thus, the plating resist 22 is formed on the mask layer 26 that exposes the first metal foil 8 in the bump forming hole 24 and covers the other portion of the first metal foil 8 (FIG. 1D). )).

Here, the bump formation hole 24 is formed at a site to be a heat dissipation path in the future by a known photoetching method, laser processing method, or the like. At least one bump forming hole 24 (four in FIG. 1D) is formed. At this time, the diameter of the bump formation hole 24 can be arbitrarily set according to the diameter of the heat dissipation path.

Next, electrolytic plating of copper is performed on the copper-clad steel plate 16 on which the mask layer 26 is formed. Thus, copper is preferentially deposited on the second surface 20 of the first metal foil 8 exposed from the bump formation hole 24, and a copper column is formed along the bump formation hole 24 (FIG. 1 (e)). The copper pillar generally does not exceed the thickness of the mask layer 26, but when it grows beyond the opening end 25 of the bump formation hole 24 as shown in FIG. A flange that extends slightly in a ring shape toward the outside in the radial direction may be formed, and the top portion 28 may have a round shape. Thereafter, the first bump 10 made of copper is formed at a predetermined position on the second surface 20 of the first metal foil 8 by removing the mask layer 26 (FIG. 1F). In this way, the first metal foil 8 having the first bump 10 is obtained. At this stage, as apparent from FIG. 1 (f), the first metal foil 8 is supported on a stainless steel plate as the first supporting substrate 14.

On the other hand, the second bump 30 is formed on the second metal foil 38 in parallel with or after the formation of the first bump 10.

The procedure for forming the second bump is shown in FIGS. 1G to 1L and is basically the same as the procedure for forming the first bump. That is, a mask layer 44 obtained by processing a plating resist 42 is formed on a copper-clad steel plate 40 in which a copper foil (second metal foil 38) is formed on a stainless steel plate (second support substrate 36), and bumps of the mask layer 44 are formed. Copper plating is performed on the portion of the formation hole 46 to form a copper pillar, and the second bump 30 is obtained. However, when the mask layer 44 is formed, the bump formation hole 46 is provided at a position facing the first bump 10. That is, when the second surface 50 of the second metal foil 38 opposite to the first surface 48 in contact with the second carrier substrate 36 is opposed to the second surface 20 of the first metal foil 8, Bump formation holes 46 for the second bumps 30 are formed in the plating resist 42 at opposite positions.

Next, the first and second supporting

substrates

14 and 36 are arranged so that the first metal foil 8 and the second metal foil 38 face each other, and the first bump 10 and the second bump are formed to form the columnar body 4. 30, and an insulating substrate 58 sandwiched between the first metal foil 8 and the second metal foil 38 and having the columnar body 4 embedded therein. A laminated body 60 is formed in which the

carrier substrates

14 and 36 are overlaid via the second metal foils 8 and 38 (lamination process).

Specifically, as shown in FIG. 1 (m), first and second metal foils 8 and 38 carried on the first and second carrying

substrates

14 and 36 are first formed into the first bump 10 and the second bump. The second surfaces 20 and 50 having the bumps 30 are opposed to each other with the main prepreg 52 interposed therebetween.

Here, the main prepreg 52 has, for example, a plate shape in which a glass fiber is impregnated with an uncured thermosetting resin. The main prepreg 52 has a main through hole 54 as shown in FIG. The main through hole 54 is provided at a predetermined position where the first bump 10 can be inserted from one side and the second bump 30 can be inserted from the other side. Yes.

Here, the alignment of the first and second metal foils 8 and 38 supported on the first and

second support substrates

14 and 36 and the main prepreg 52 is performed using, for example, a pin lamination method.

After the first and second metal foils 8 and 38 carried on the first and second carrying

substrates

14 and 36 and the main prepreg 52 are aligned, the first and

second bumps

10 and 30 are placed on the main prepreg 50. While being inserted into the main through hole 54, the first and

second carrier substrates

14 and 36 are pressed toward each other and the whole is heated.

At this time, the first bump 10 and the second bump 30 have the

top portions

28 and 56 abutted against each other and thermocompression bonded, and the columnar body 4 connecting the first metal foil 8 and the second metal foil 38 to each other. Become. The columnar body 4 is used as a heat dissipation path in the circuit board 2. Specifically, as shown in FIG. 2A, the first and

second bumps

10 and 30 are integrated by collapsing and deforming the

top portions

28 and 56, so that the columnar body 4 having high heat radiation efficiency is obtained. be able to. Moreover, this columnar body 4 is the same also about conduction | electrical_connection, and can ensure the stable electroconductivity.

On the other hand, simultaneously with the formation of the columnar body 4, the uncured thermosetting resin of the main prepreg 52 is pressed and flows, spread around the columnar body 4, and the like between the through hole 54 and the columnar body 4. Meet. Thereafter, such a thermosetting resin is cured by being heated. As a result, the main prepreg 52 is formed on the insulating substrate 58 in which the columnar body 4 is embedded.

As a result, as shown in FIG. 2A, a laminate 60 in which the first and second carrying

substrates

14 and 36 are overlapped on both surfaces of the insulating substrate 58 via the first and second metal foils 8 and 38, respectively. Is obtained.

Next, the first and second metal foils 8 and 38 are formed on the first and

second wiring patterns

6 and 62, respectively (pattern forming step).

In this step, first, as shown in FIG. 2B, the first and

second support substrates

14 and 36 are peeled off from the first metal foil 8 and the second metal foil 38, respectively, and the first metal foil 8 and the first metal foil 8 The first surfaces 18 and 48 of the two metal foils 38 are exposed.

Next,

wiring patterns

6 and 38 are formed on the first metal foil 8 and the second metal foil 38 by using a normal etching method. Specifically, an etching resist is applied to the portions of the first metal foil 8 and the second metal foil 38 that are to be left as wiring, and unnecessary portions are removed by etching, thereby forming

wiring patterns

6 and 62 having a predetermined shape. (FIG. 2 (c)). Then, in the obtained

wiring patterns

6 and 62, only the portions that require soldering are exposed, and the solder resist layer 64 is formed so that the solder does not adhere to the portions that do not require soldering. Thus, the insulating substrate 58, the first and

second wiring patterns

6, 62 having a predetermined shape formed on the front and back surfaces of the insulating substrate 58, and the first and second wiring patterns 6 built in the insulating substrate 58 are provided. , 62 is obtained as a circuit board 2 provided with a copper columnar body 4 as a heat radiation path (FIG. 2D).

The circuit board 2 provided with the heat dissipation path obtained in this way is then mounted with electronic components or processed according to the board shape to be used.

As described above, in the method of manufacturing the circuit board 2 according to the present invention, the first metal foil 8 and the second metal foil 38 are opposed to each other with the main prepreg 52 interposed therebetween. At this time, since the first and

second bumps

10 and 30 of the first and second metal foils 8 and 38 are abutted and integrated with each other through the main through hole 54 of the main prepreg 52, the first wiring pattern 6 and the second wiring The columnar body 4 connecting the pattern 62 is secured as a heat dissipation path. Since this heat dissipation path is not formed by a manufacturing process separately provided in the manufacturing process of the circuit board 2, the entire circuit board can be quickly manufactured. In addition, a heat dissipation path having a desired diameter can be easily formed without being limited by the hole diameter, as compared with the conventional method of filling the through hole with a metal paste. Further, since the

bumps

10 and 30 to be the columnar bodies 4 are formed by plating, even if the number of heat dissipation paths is increased, a large number of bumps can be formed by plating at the same time, and a reduction in work efficiency is suppressed. . In addition, the columnar body 4 can be used not only for the purpose of heat dissipation but also as a means for achieving conduction between the wiring patterns on both sides.

(Second Embodiment)
As a second embodiment, a method for manufacturing a circuit board capable of securing a heat dissipation path for the circuit board 70 for a large current through which a large current flows will be described below with reference to FIGS. In the description of the second embodiment, the same reference numerals are assigned to the related members and parts for the operation procedures of the same steps as those of the first embodiment already described, and the description thereof is omitted. Only the differences will be described.

In the second embodiment, a thick conductor 72 for providing a thick wiring pattern thicker than the first wiring pattern 6 is further formed in the bump forming process by the same formation method as that of the first bump 10. To do. Specifically, a thick conductor forming hole 74 for the thick conductor 72 is further formed in a predetermined portion where the thick conductor 72 is to be formed in the plating resist layer 22 shown in FIG. )), Plating is performed on the thick conductor formation hole 74 for the thick conductor 72 simultaneously with the bump formation hole 24 for the first bump 10, and the thick conductor 72 is formed in the same manner as the first bump 10.

The thick conductor 72 is provided along the wiring through which a large current flows in the first wiring pattern 6 formed on the surface of the circuit board 70. That is, the thick conductor 72 is formed on a portion of the first metal foil 8 that should be a wiring pattern through which a large current flows. As a result, in the first wiring pattern 6, a portion where the thick conductor 72 exists is locally thick, and the portion becomes a thick wiring pattern, so that a large current can flow.

Next, by removing the mask layer 26, the first metal foil 8 in which the thick conductor 72 is formed in addition to the first bump 10 is obtained (FIG. 3F).
Since the thick conductor 72 is different from the first bump 10, the second bump 30 is not provided on the second metal foil 38 at a position facing the thick conductor 72.

Next, in the stacking step, a main prepreg 52 provided with a partial main through hole 55 that forms a part of the main through hole 54 at a position corresponding to each of the first and

second bumps

10 and 30 is prepared. A sub-prepreg provided with a sub through hole 78 into which the thick conductor 72 is to be inserted at a position corresponding to the remaining main through hole 57 and the thick conductor 72 that form the main through hole 54 in cooperation with the main through hole 55. 76 is prepared. These two prepregs 52 and 76 are disposed between the first and second metal foils 8 and 38. At this time, the sub-prepreg 76 is arranged on the metal foil side on which the thick conductor 72 is formed, that is, on the first metal foil 8 side in this embodiment (FIG. 3 (m)). In this state, the first and

second support substrates

14 and 36 are pressed in a direction approaching each other, and the whole is heated. Thereby, the thick conductor 72 is embedded in the insulating substrate 58 (FIG. 4A). Then, similarly to the circuit board 2 described above, the first and

second carrier boards

14 and 36 are peeled off (FIG. 4B), and the first and

second wiring patterns

6 and 62 are formed (FIG. 4C). ) And a solder resist layer 64 is formed (FIG. 4D). Thereby, the circuit board 70 for large current is manufactured.

In this circuit board 70, since the thickness of the first metal foil 8 (copper foil) on the surface is not different from the conventional one, even if a thick thick conductor 72 is formed in the insulating substrate 58 for a large current, it is fine. A simple wiring pattern can be formed. Further, by using the sub prepreg 76 in which the sub through holes 78 are formed at positions corresponding to the thick conductors 72, the laminating process can be performed easily and quickly. The circuit board 70 has the same structure, operation, and effects as those of the circuit board 2.

2 Circuit board 4 Columnar body (heat dissipation path)
6 1st wiring pattern 8 1st metal foil 10 1st bump 14 1st support substrate 24 bump formation hole 26 mask layer 28 top 30 2nd bump 36 2nd support substrate 38 2nd metal foil 44 mask layer 46 bump formation hole 52 Main prepreg 54 Main through hole 62 Second wiring pattern 70 Circuit board 72 Thick conductor 74 Thick conductor forming hole 78 Sub through hole

Claims

An insulating substrate; a first wiring pattern formed on one surface of the insulating substrate; a second wiring pattern formed on the other surface; and the first and second wiring patterns provided in the insulating substrate. A circuit board manufacturing method comprising a heat dissipation path made of a metal columnar body that is thermally connected,
First and second supporting substrates are prepared, and a first metal foil on which the first wiring pattern is to be formed is formed on the first supporting substrate, while a second wiring pattern is to be formed on the second supporting substrate. A preparation step of forming a metal foil;
A bump forming step of forming, on the first and second metal foils, metal first and second bumps each having a height approximately half of the columnar body by plating;
The first and second supporting substrates are disposed so that the first metal foil and the second metal foil face each other, and the first bump and the second bump are butted against each other to form the columnar body. While
The insulating substrate sandwiched between the first metal foil and the second metal foil and having the columnar body embedded therein is formed, and the first and second metal foils are interposed on both surfaces of the insulating substrate. A laminating step of forming a laminated body in which the carrier substrates are superposed;
After peeling off the first and second supporting substrates from the laminate to expose the first and second metal foils, the first and second metal foils are used as the first and second wiring patterns. A circuit board manufacturing method comprising: a pattern forming process for forming each pattern.
The laminating step includes
A plate-shaped main prepreg having one main through-hole into which the first and second bumps are to be inserted, and preparing a main prepreg containing uncured insulating resin,
In order to insert the first and second bumps into the main through-holes of the main prepreg and to bring the tips of the first and second bumps into contact with each other, the first and second support substrates on both sides of the main prepreg. Then, the first and second support substrates are pressed in a direction approaching each other, thereby integrating the first and second bumps into the columnar body, and the main prepreg The method for manufacturing a circuit board according to claim 1, wherein the insulating substrate is formed by flowing the insulating resin to embed the columnar body.
The bump forming step includes
Further forming a thick conductor for providing a thick wiring pattern thicker than the first wiring pattern by the same formation method as the first bump formation method on the first metal foil,
The laminating step includes
A main prepreg having a partial main through hole that forms a part of the main through hole, a remaining main through hole that forms the main through hole in cooperation with the partial main through hole, and the thick conductor are inserted. A sub-prepreg each having a sub-through hole to be prepared, and further comprising a sub-prepreg containing an uncured insulating resin,
Prior to pressing the first and second supporting substrates, the first and second supporting substrates are arranged to sandwich the sub-prepreg and the main prepreg between the first metal foil and the second metal foil, The method for manufacturing a circuit board according to claim 2, wherein the thick conductor is inserted into the sub through hole of the sub prepreg.