JP4781814B2 - Manufacturing method and manufacturing apparatus for build-up type multilayer printed wiring board - Google Patents

Description

  The present invention relates to a manufacturing method and a manufacturing apparatus for a build-up type multilayer printed wiring board which is one form of a multilayer printed wiring board.

  In order to meet demands for higher performance and smaller size of electronic devices, printed wiring boards are required to have higher density and thickness. In order to meet these requirements, a build-up type multilayer printed wiring board, which is one form of the multilayer printed wiring board, has attracted attention.

  A build-up type multilayer printed wiring board is generally composed of a wiring layer formed on both sides of a core material mainly composed of a resin and a through hole formed by drilling, for example, to connect the wiring layers. An IVH (Interstitial Via Hole), an insulating layer formed so as to cover the IVH and each wiring layer, and a non-through hole LVH (Laser Via) formed by laser processing or the like at a predetermined position of the insulating layer Hole) and a through hole which is a through hole formed by drilling, a wiring layer formed on the surface of the insulating layer so as to cover the inner wall of the LVH and the through hole, and a predetermined opening on the wiring layer And a solder resist layer formed.

In addition, as a method for forming the above-described insulating layer or solder resist layer, a screen printing method in which an insulating resin ink or solder resist ink is applied to a wiring board using a screen, an insulating resin sheet or the like using a vacuum laminator is used. There are a vacuum laminating method and a roll coating method.
In the roll coating method, an insulating layer or a solder resist layer is formed by sandwiching a wiring board between a pair of coating rolls in a state where the wiring board stands vertically, and insulating resin ink on both sides of the wiring board through the roll. Since it can be applied simultaneously to the side, the productivity is superior to the screen printing method in which each side is applied.
In addition, when forming an insulating layer or a solder resist layer, it is possible to use an inexpensive insulating resin ink and solder resist ink, so that the manufacturing cost can be reduced compared to a vacuum laminating method using an expensive insulating resin sheet. This is advantageous.
Therefore, the roll coating method is an effective method for forming the insulating layer and the solder resist layer in the manufacturing method of the build-up type multilayer printed wiring board.

Patent Document 1 describes a method for manufacturing a printed wiring board in which an insulating layer and a solder resist layer are formed by a roll coating method.
According to the description of Patent Document 1, the coating pressure on the surface of the wiring board with the smaller area ratio of the wiring pattern is made smaller than the coating pressure on the surface of the wiring pattern with the larger area ratio, so that Even on wiring boards having different wiring pattern area ratios, an insulating layer and a solder resist layer having a uniform film thickness can be formed on the front and back surfaces.
JP 2001-144419 A

  By the way, in the method for manufacturing a printed wiring board described in Patent Document 1, when an insulating layer is formed, an insulating resin ink is simultaneously applied to both sides of the wiring board, so that voids are generated inside the IVH of the wiring board. There is a case. This void is called an IVH internal void. The build-up type multilayer printed wiring board having voids in IVH is subjected to thermal stress by a thermal shock test which is one of reliability tests. The wiring layer may be disconnected.

  The reason why the voids in IVH are generated will be described with reference to FIG. FIG. 16 is a schematic cross-sectional view illustrating a state in which the insulating resin ink 112 is filled into the IVH 105 of the wiring board 100 using a pair of rolls 110a and 110b. Moreover, (a), (b), and (c) in FIG. 16 show a state in which the wiring board 100 moves in the direction of the arrow Ed in that order. Also, arrows Ea and Eb in FIG. 16 indicate the rotation directions of the pair of rolls 110a and 110b.

  As shown in FIG. 16, the pair of rolls 110 a and 110 b have the same contact area in contact with the wiring board 100, that is, contact with one roll 110 a and the wiring board 100 in the transport direction Ed of the wiring board 100. Since the length of the surface 125a and the length of the other roll 110b, the wiring board 100, and the contact surface 125b are substantially equal, the insulating resin ink 112 is injected into the IVH 105 almost simultaneously from the roll 110a and the roll 110b. For this reason, it is considered that the air inside the IVH 105 is trapped, and the trapped air becomes the void G in the IVH.

Moreover, since the manufacturing method of the printed wiring board of patent document 1 applies a soldering resist ink simultaneously on both surfaces side of a wiring board when forming a soldering resist layer, it is a wiring board for the reason similar to the reason mentioned above. Voids may occur inside the through-holes. This void is referred to as a through-hole void.
When mounting electronic components etc. on a build-up type multilayer printed wiring board with through-hole voids using cream solder etc., the voids in the through-holes are generated when the wiring board is heated in the reflow process to melt the cream solder. There is a possibility that the mounting position of an electronic component or the like placed in the range corresponding to the through hole and in the vicinity thereof may shift due to thermal expansion and rupture. If the displacement amount of the mounting position of the electronic component is large, a conduction failure occurs between the wiring board and the electronic component, and the function as a mounting substrate is impaired.
Since the thickness of the wiring board when forming the solder resist layer is thicker than the thickness of the wiring board when forming the insulating layer, the aspect ratio of the through hole (when the inner diameter of the IVH is substantially equal to the inner diameter of the through hole) Since the ratio of the length to the inner diameter of the through hole) is larger than the aspect ratio of IVH, it is considered that the void in the through hole is generated with a higher probability than the void G in the IVH.

  Accordingly, the problem to be solved by the present invention is to provide a printed wiring board manufacturing method and manufacturing apparatus that suppress voids generated in IVH and through holes when forming an insulating layer and a solder resist layer. .

In order to solve the above problems, each invention of the present application has the following means.
1) While forming wiring patterns (8a, 8b) on both surfaces of a core material having a through hole (4) and being bendable, conductive layers (5a, 8b) covering these wiring patterns with the inner surface of the through hole 5b) to prepare a double-sided wiring board (9) electrically connected through, and then transport the double-sided wiring board in one direction through a nip between a pair of rolls in the roll coater (10a), Insulating ink (11a, 31a) is applied to both surfaces of the double-sided wiring board by the roll coater (10a) to form an insulating layer covering the wiring pattern, and at the same time, the through hole (4) is filled with the insulating ink. In the manufacturing method of the build-up type multilayer printed wiring board that performs the ink application process, the ink application process includes a step of the part of the double-sided wiring board that faces the nip opening. Is a manufacturing method of a buildup type multilayer printed wiring board, characterized in that it is carried out in a state in which along the outer peripheral surface of the square of the roll (12b).
2) Conductive layers covering the inner surface of the through hole (4) while forming the wiring patterns (8a, 8b) on both surfaces of the core material having the through hole (4) and being bendable. The double-sided wiring board (9) electrically connected via (5a, 5b) is prepared, and then the double-sided wiring when the double-sided wiring board is transported in one direction and passes through the roll coater (10a). An insulating ink (11a, 31a) is applied to both surfaces of the substrate by a roll coater (10a) to form an insulating layer that covers the wiring pattern, and at the same time, a build-up type multilayer printed wiring board that fills the through hole with the insulating ink. In the manufacturing apparatus, the roll coater (10a) is a pair of rolls (12a, 12b) that can contact and separate from each other, and allows the double-sided wiring board (9) to pass between these rolls. A pair of rolls (12a, 12b) that form a nip opening that accommodates the ink, and an ink supply means (14a, 14b) that supplies the insulating ink to each of the pair of rolls; Including a guide member that sandwiches the double-sided wiring board with one roll upstream and guides the conveyance of the double-sided wiring board, and a portion of the double-sided wiring board from the guide member to the nip opening In contact with the outer peripheral surface of the roll (12b), the bending means (30) for bending along the outer peripheral surface, and the rotational driving of the pair of rolls, the wire core material is conveyed in the one direction. And a build-up type multilayer printed wiring board manufacturing apparatus characterized by having a conveying means (15a).

  According to the present invention, in a manufacturing method and a manufacturing apparatus of a build-up type multilayer printed wiring board, an insulating resin ink, a solder resist ink, etc. using a roll coater having a pair of rolls on both sides of the wiring board having a through hole When the ink is applied, the wiring board is curved along the outer peripheral surface of one of the pair of rolls, so that the ink can be put into the IVH or the through hole that is a through hole. And the generation of voids in the through hole can be suppressed.

An embodiment of the present invention will be described with reference to FIGS.
1 and 2 are schematic cross-sectional views for explaining a first step and a second step, respectively, in an embodiment of the method for manufacturing a build-up type multilayer printed wiring board according to the present invention.
FIG. 3 is a process flow diagram for explaining a method for forming an insulating layer and a solder resist layer in an embodiment of the method for manufacturing a build-up type multilayer printed wiring board according to the present invention.
4 and 5 are schematic cross-sectional views for explaining the third step in the embodiment of the manufacturing method of the build-up type multilayer printed wiring board of the present invention, and the build-up type multilayer printed wiring board of the present invention. It is typical sectional drawing for demonstrating the Example of this manufacturing apparatus.
FIG. 6 is a schematic cross-sectional view for explaining a third step in the embodiment of the method for manufacturing a build-up type multilayer printed wiring board according to the present invention.
7 and 8 are schematic cross-sectional views for explaining the fourth step in the embodiment of the method for manufacturing a build-up type multilayer printed wiring board according to the present invention.
FIGS. 9 to 13 are schematic cross-sectional views for explaining the fifth to ninth steps in the embodiment of the method for manufacturing a build-up type multilayer printed wiring board according to the present invention.
FIG. 14 is a schematic cross-sectional view for explaining an eleventh step in the embodiment of the manufacturing method of the build-up type multilayer printed wiring board of the present invention.

  Examples of the manufacturing method and manufacturing apparatus of the build-up type multilayer printed wiring board of the present invention will be described below. In addition, the manufacturing method of the buildup type multilayer printed wiring board demonstrated below is a manufacturing method of the buildup type multilayer printed wiring board which has four wiring layers.

<Example>
In the embodiment, in the step of forming the insulating layer and the solder resist layer by using the roll coating method, the insulating resin ink and the solder resist ink are applied to the wiring board in a state where the wiring board is curved, whereby IVH ( Interstitial Via Hole) and IVH voids and through-hole voids generated in the through-holes are suppressed.
Examples will be described below as first to eleventh steps with reference to FIGS.

(First step) [See FIG. 1]
Copper is placed at a predetermined position on a double-sided copper-clad plate 3 in which copper foils 2a and 2b having a thickness of 12 μm are bonded to the front and back surfaces of the core material 1 which is a resin substrate having a length of 340 mm, a width of 510 mm, and a plate thickness of 0.4 mm. An IVH (Interstitial Via Hole) 4 for electrically connecting the foils 2a and 2b is formed as a through hole.
This IVH4 can be formed by drilling or laser processing. In the example, IVH4 having a diameter of about 0.2 mm was formed by drilling.
In addition, the thickness of the core material 1 and copper foil 2a, 2b and the diameter of IVH4 are not limited to an Example.

(Second step) [See FIG. 2]
For example, first plating layers 5a and 5b made of copper are formed on the inner surface of IVH4 and the surfaces of copper foils 2a and 2b. The first plating layers 5a and 5b are formed, for example, by performing electroless copper plating and further electrolytic copper plating. In the embodiment, the thickness of the first plating layers 5a and 5b is about 20 μm. The plating conditions were set in
Next, the first wiring layer 6 is formed by selectively etching the first plating layer 5a and the copper foil 2a so as to obtain a predetermined wiring pattern 8a by photolithography, and a predetermined wiring pattern 8b is obtained. In this manner, the second wiring layer 7 is formed by selectively etching the first plating layer 5b and the copper foil 2b.
The double-sided copper-clad board 3 that has undergone the above-described steps is referred to as a double-sided wiring board 9.

Next, an insulating layer is formed on the front and back surfaces of the double-sided wiring board 9 using a roll coating method.
Therefore, first, an outline of a method for forming this insulating layer will be described with reference to FIG.
FIG. 3 is a process flow diagram for explaining an outline of a method for forming an insulating layer and a method for forming a solder resist layer described later.
The method of forming the insulating layer will be described in detail later. As shown in FIG. 3, the first insulating resin ink 11a is applied to both surfaces of the double-sided wiring board 9 by using the first roll coater 10a. A first coating step for forming one resin ink layer 18a, 18b, and a second insulating resin ink 11b on the first resin ink layer 18a, 18b, using a second roll coater 10b. The second resin ink layer 19a, 19b is applied to form the second resin ink layer 19a, 19b, and the first resin ink layer 18a, 18b and the second resin ink layer 19a, 19b are simultaneously cured to form an insulating layer. 20 and 21, a curing step.
The first application process is a process mainly intended to fill the IVH4 with the first insulating resin ink 11a while suppressing the generation of voids in the IVH4, and the second application process mainly includes the second application process. This is a process aimed at setting the thickness of the insulating layer to a predetermined thickness with the insulating resin ink 11b.

  Hereinafter, the first application process will be described as a third process, the second application process as a fourth process, and the curing process as a fifth process.

(Third Step) [Refer to FIGS. 4 to 6]: First Application Step In the first application step, the first insulating resin ink 11a is applied to both surfaces of the double-sided wiring board 9 using the first roll coater 10a. The purpose is to fill the inside of the IVH 4 and the gap between the wiring patterns 8a and 8b with the first insulating resin ink 11a when applied to the side.

First, the structure of the 1st roll coater 10a used at a 1st application | coating process is demonstrated using FIG.4 and FIG.5.
As shown in FIG. 4, the first roll coater 10a used in the first coating step includes a pair of rolls 12a and 12b and a pair of doctor bars 13a disposed so as to come into contact with the pair of rolls 12a and 12b, respectively. , 13b, storage portions 14a, 14b for storing the first insulating resin ink 11a, and the double-sided wiring board 9 produced in the second step described above, and the double-sided wiring board 9 is paired with a pair of rolls. It has the attachment part 15a which has a drive means for making it pass between 12a and 12b, and the roller part 30 which is a bending means to bend the double-sided wiring board 9. As shown in FIG.
Moreover, the drive part which moves the roll part 16a which consists of the roll 12a, the doctor bar 13a, and the storage part 14a, and the roll part 16b which consists of the roll 12b, the doctor bar 13b, and the storage part 14b to contact and separate each. (Not shown).

  In order to fill the IVH4 of the double-sided wiring board 9 with the first insulating resin ink 11a while suppressing the generation of voids in the IVH4, the roller unit 30 places the double-sided wiring board 9 on the outer peripheral surface of one roll 12b. The length of the double-sided wiring board 9 in the moving direction at the contact surface between the roll 12b and the double-sided wiring board 9, and the length of the double-sided wiring board 9 at the contact surface between the other roll 12a and the double-sided wiring board 9 is curved. This is for making it longer than the length in the moving direction.

  In the embodiment, a cylindrical stainless material having a diameter of about 8 mm is used as the roller portion 30, and the contact position when the double-sided wiring board 9 is moved in the direction of the arrow Ec <b> 1 and brought into contact with the roller portion 30 is the position of the roller portion 30. Both end portions of the roller portion 30 were fixed to the first roll coater 10a so as to be positioned closer to the roll 12b than the axis O.

  Further, the roller unit 30 may be movable in the directions of the arrows Ed and Ec1 of the double-sided wiring board 9 and fixed at an arbitrary position. Since the degree of curvature of the double-sided wiring board 9 can be changed by moving the roller part 30 in the directions of arrows Ed and Ec1, the moving direction of the double-sided wiring board 9 on the contact surface between the roll 12b and the double-sided wiring board 9 And the length in the moving direction of the double-sided wiring board 9 on the contact surface between the other roll 12a and the double-sided wiring board 9 can be set to an arbitrary value.

That is, the degree of curvature of the double-sided wiring board 9 can be increased by moving the roller portion 30 in the direction of the arrow Ed, so that the double-sided wiring board 9 moves on the contact surface between the roll 12b and the double-sided wiring board 9. The length in the direction can be made longer than the length in the moving direction of the double-sided wiring board 9 on the contact surface between the roll 12a and the double-sided wiring board 9.
Further, by moving the roller portion 30 in the direction of the arrow Ed, when the double-sided wiring board 9 is moved in the direction of the arrow Ed, it is possible to hold the curved state of the double-sided wiring board 9 for a longer time. .

  In addition, since the degree of curvature of the double-sided wiring board 9 can be reduced by moving the roller unit 30 in the direction of the arrow Ec1, the double-sided wiring board 9 moves on the contact surface between the roll 12b and the double-sided wiring board 9. The difference between the length in the direction and the length in the moving direction of the double-sided wiring board 9 on the contact surface between the roll 12a and the double-sided wiring board 9 can be reduced.

  Since the degree of curvature of the double-sided wiring board 9 varies depending on the thickness and material of the double-sided wiring board 9, the configuration of the double-sided wiring board 9, etc., the arrangement position of the roller unit 30 is set within a range that does not damage the double-sided wiring board 9. It is necessary.

  Further, the roller unit 30 may be rotatable about the axis O as a rotation axis. By making the roller part 30 rotatable, the double-sided wiring board 9 can be moved more smoothly by rotating the roller part 30 in the moving directions Ed and Ec2 of the double-sided wiring board 9.

  Moreover, the shape of the roller part 30 is not limited to an Example, For example, let the shape of the roller part 30 be plate shape, and one surface of this roller part 30 becomes substantially parallel to the moving direction Ec of the double-sided wiring board 9. At the same time, when the double-sided wiring board 9 is moved by moving the double-sided wiring board 9 in the direction of the arrow Ec1, the roller part 30 is arranged so that the double-sided wiring board 9 contacts the roller part 30. Since the double-sided wiring board 9 is in contact with the surface, the curved state of the double-sided wiring board 9 can be further stabilized.

  In addition, the material of the roller part 30 is not limited to the embodiment, but the double-sided wiring board 9 may be a material that does not damage the double-sided wiring board 9 when the double-sided wiring board 9 is in contact with the roller part 30. desirable.

Next, the pair of rolls 12a and 12b described above will be described with reference to FIG.
As shown in FIG. 5, each of the pair of rolls 12a and 12b has a columnar shape, and grooves 17a extending in the circumferential direction are formed at a constant pitch La (corresponding to the opening width) La on the outer periphery of the roll 12a. A plurality of grooves 17b extending in the circumferential direction are formed at a constant pitch (corresponding to the opening width) Lb on the outer peripheral portion of the roll 12b.
Further, the grooves 17a and 17b may be formed so as to extend in a spiral shape in the circumferential direction at a constant pitch (corresponding to the opening width) La and Lb.

In the embodiment, each of the pair of rolls 12a and 12b has a diameter Ra and Rb of about 110 mm, a material made of ethylene propylene rubber (also referred to as EPT), and a hardness Hv of 60.
Further, the groove 17a of the roll 12a has a pitch (opening width) La of 120 μm, a depth ta of 60 μm, and an opening angle θa of 90 degrees, and the groove 17b of the roll 12b has a pitch (opening width) Lb of 120 μm and a depth. The thickness tb is 60 μm and the opening angle θb is 90 degrees.
Further, the shapes and dimensions of the grooves 17a and 17b of the rolls 12a and 12b described above are not limited to those in the embodiment. For example, a non-through hole (also referred to as a bottomed hole) is formed in a double-sided wiring board. In this case, it is preferable to make the opening widths La and Lb narrower than the opening diameter of the non-through hole. By making the opening widths La and Lb narrower than the opening diameters of the non-through holes, air in the non-through holes can be easily released when the first insulating resin ink 11a is applied to the double-sided wiring board. Voids generated in the through hole can be suppressed.

Next, a method for applying the first insulating resin ink 11a will be described with reference to FIG.
The first insulating resin ink 11a is adjusted to have a predetermined viscosity, for example, a viscosity in the range of 3 to 6 Pa · s, and then supplied to the storage units 14a and 14b.
Next, when the pair of rolls 12a and 12b are rotated in the directions of the arrows Ea and Eb by a driving means (not shown), the first insulating resin ink 11a stored in the storage portions 14a and 14b is transferred to the pair of rolls 12a. 12b enters the grooves 17a and 17b. In the example, the rotation speed at each outer peripheral portion of the pair of rolls 12a and 12b was set to 1.2 m / min. The rotational speed is not limited to the embodiment, but a predetermined amount of the first insulation is provided on the double-sided wiring board 9 by setting the rotational speed to be faster than the conveyance speed of the double-sided wiring board 9 described later. Resin ink 11a can be stably supplied.

Next, as shown in FIG. 4, the double-sided wiring board 9 produced in the second step is fixed to the attachment portion 15a.
Then, the roll part 16a and the roll part 16b are moved in the direction which each leaves | separates with the drive means which is not shown in figure.
Further, when the attachment portion 15a is moved in the direction of the arrow Ec1 by a driving means (not shown) and the predetermined area on both sides of the double-sided wiring board 9 has passed between the pair of rolls 12a and 12b, the attachment portion 15a is stopped.

Here, the moving direction of the double-sided wiring board 9 will be described.
First, the double-sided wiring board 9 moves in the direction of the arrow Ec1 and passes between the pair of rolls 12a and 12b and contacts the roller unit 30.
And since the double-sided wiring board 9 which contacted the roller part 30 has arrange | positioned the roller part 30 so that the axis | shaft O may be located in the roll 12a side rather than the centerline c1 of the thickness direction of the double-sided wiring board 9, It moves in the direction of arrow Ec2 between the roller part 30 and the roll 12b.

Next, the roll part 16a and the roll part 16b are moved in directions in which the roll part 16a and the roll part 16b approach each other by a driving unit (not shown), and the rolls 12a and 12b are brought into contact with the double-sided wiring board 9, respectively. By this contact, the double-sided wiring board 9 is curved in the circumferential direction along the outer peripheral surface of the roll 12 b by the roller unit 30.
The double-sided wiring board 9 can be bent because it is composed of the core material 1 mainly composed of resin and the wiring patterns 8a and 8b made of copper. However, the degree of bending is determined by the thickness of the substrate as described above. Since it depends on the material, the configuration of the board, and the like, it is necessary to bend the printed board within a range that does not damage the printed board.

Thereafter, the mounting portion 15a is moved in the direction of the arrow Ed at a predetermined speed, for example, about 0.8 m / min, by a driving means (not shown) to fill the grooves 17a and 17b of the pair of rolls 12a and 12b. The first insulating resin ink 11 a is transferred to the front and back surfaces of the double-sided wiring board 9.
After the double-sided wiring board 9 has completely passed between the pair of rolls 12a and 12b, the attachment portion 15a is stopped.
Then, the double-sided wiring board 9 is removed from the attachment part 15a.

Through the above steps, as shown in FIG. 6, first resin ink layers 18a and 18b made of the first insulating resin ink 11a are formed in predetermined regions on both sides of the double-sided wiring board 9.
The inside of the IVH 4 and the space between the wiring patterns were filled with the first insulating resin ink 11a, and it was confirmed that the IVH void G, which was a problem in the past, was not generated. The reason why the IVH void G has not occurred will be described in detail later.
The first resin ink layers 18a and 18b on the first wiring layer 6 and the second wiring layer 7 are formed to be very thin with a thickness of about 5 μm or less, and the first resin ink layers 18a and 18b It was confirmed that the surface of 18b was a substantially smooth surface by filling the steps of the wiring patterns 8a and 8b with the first insulating resin ink 11a.

(4th process) [Refer FIG.5, FIG.7, FIG.8]: 2nd application | coating process Next, the 2nd application | coating process which is a 4th process is demonstrated.
In the second coating step, the second resin ink layers 19a and 19b are formed so that a first insulating layer 20 and a second insulating layer 21 to be described later have a predetermined thickness (60 μm in the embodiment). Is the purpose.

First, the structure of the 2nd roll coater 10b used at a 2nd application | coating process is demonstrated using FIG.5 and FIG.7.
As shown in FIG. 7, the second roll coater 10b used in the second coating step includes a pair of rolls 12c and 12d and a pair of doctor bars 13c arranged so as to come into contact with the pair of rolls 12c and 12d, respectively. , 13d, storage portions 14c, 14d for storing the second insulating resin ink 11b, and the double-sided wiring board 9 produced in the first application step are fixed, and the double-sided wiring board 9 is fixed to a pair of rolls 12c. , 12d, and a mounting portion 15b having a driving means for passing between them.
In addition, the roll part 16c which consists of the roll 12c, the doctor bar 13c, and the storage part 14c, and the roll part 16d which consists of the roll 12d, the doctor bar 13d, and the storage part 14d move each in the direction which contacts / separates. Connected with.

Further, as shown in FIG. 5, each of the pair of rolls 12c and 12d has a cylindrical shape, and grooves 17c extending in the circumferential direction are formed at a constant pitch (corresponding to the opening width) on the outer peripheral portion of the roll 12c. A plurality of grooves Ld are formed at a constant pitch (corresponding to the opening width) Ld.
The grooves 17c and 17d may be formed so as to extend in a spiral shape in the circumferential direction at a constant pitch (corresponding to the opening width) Lc and Ld.

In the embodiment, each of the pair of rolls 12c and 12d has a diameter Ra and Rb of about 110 mm, a material made of ethylene propylene rubber (also referred to as EPT), and a hardness Hv of 60.
Further, the groove 17c of the roll 12c has a pitch (opening width) Lc of 1 mm, a depth tc of 0.5 mm, and an opening angle θc of 90 degrees, and the groove 17d of the roll 12d has a pitch (opening width) Ld of 1 mm. The depth td is 0.5 mm and the opening angle θd is 90 degrees.

Next, a method for applying the second insulating resin ink 11b will be described with reference to FIG.
As shown in FIG. 7, the second insulating resin ink 11b is supplied to the storage units 14c and 14d. In the examples, the second insulating resin ink 11b was the same as the first insulating resin ink 11a used in the first application step.
Next, when the pair of rolls 12c and 12d are rotated in the directions of the arrows Ea and Eb by driving means (not shown), the second insulating resin ink 11b stored in the storage portions 14c and 14d is paired with the pair of rolls. It enters into the grooves 17c and 17d of 12c and 12d. In the example, each rotational speed of the pair of rolls 12c and 12d was set to 1.2 m / min. The rotational speed is not limited to the embodiment, but a predetermined amount of the second insulation is provided on the double-sided wiring board 9 by setting the rotational speed to be higher than the conveyance speed of the double-sided wiring board 9 described later. Resin ink 11b can be supplied stably.

Next, the double-sided wiring board 9 produced in the third step is fixed to the attachment portion 15b.
Then, the roll part 16c and the roll part 16d are moved in the direction which each leaves | separates with the drive means which is not shown in figure.
Further, the attachment portion 15b is moved in the direction of the arrow Ef by a driving means (not shown), and when the predetermined area on both sides of the double-sided wiring board 9 has passed between the pair of rolls 12a and 12b, the attachment portion 15b is attached. The part 15b is stopped.
Next, the roll part 16c and the roll part 16d are moved in the direction in which they approach each other by a driving means (not shown) to bring the rolls 12c and 12d into contact with the double-sided wiring board 9, respectively.

Thereafter, the mounting portion 15b is moved in the direction of the arrow Ed at a predetermined speed, for example, 0.8 m / min, by a driving means (not shown), and the grooves 17c and 17d of the pair of rolls 12c and 12d are filled. The second insulating resin ink 11b is transferred to the surfaces of the first resin ink layers 18a and 18b of the double-sided wiring board 9.
Further, after the double-sided wiring board 9 has completely passed between the pair of rolls 12c and 12d, the attachment portion 15b is stopped.
Then, the double-sided wiring board 9 is removed from the attachment part 15b.

As shown in FIG. 8, the second resin ink made of the second insulating resin ink 11b is formed on the first resin ink layers 18a and 18b formed on the both surfaces of the double-sided wiring board 9, as shown in FIG. Layers 19a and 19b are formed.
The first resin ink layers 18a and 18b made of the uncured first insulating resin ink 11a and the second resin ink layers 19a and 19b made of the uncured second insulating resin ink 11b In the vicinity of the interface, they are mixed with each other, and it is difficult to confirm the boundary surface clearly.
Therefore, the total thickness te, tf of the first resin ink layers 18a, 18b and the second resin ink layers 19a, 19b (thickness from the surface of the first wiring layer 6 to the surface of the second resin ink layer 19a). , Thickness from the surface of the second wiring layer 7 to the surface of the second resin ink layer 19b), the total thickness te and tf are both about 80 μm, and the surface is a substantially smooth surface. It was confirmed.

(Fifth Step) [Refer to FIG. 9]: Curing Step The first resin ink layers 18a and 18b and the second resin ink are heated by heating the double-sided wiring board 9 that has undergone the above-described steps at, for example, 150 ° C. for one hour. The solvent in the layers 19a and 19b is evaporated, and the first resin ink layers 18a and 18b and the second resin ink layers 19a and 19b are cured to obtain the first insulating layer 20 and the second insulating layer 21. The first insulating resin ink 11a for forming the first resin ink layers 18a and 18b and the second insulating resin ink 11b for forming the second resin ink layers 19a and 19b are as follows. Since the main components are the same, the first insulating layer 20 and the second insulating layer 21 have a uniform resin component.
Thickness tg, th of the first insulating layer 20 and the second insulating layer 21 (thickness from the surface of the first wiring layer 6 to the surface of the first insulating layer 20, the surface of the second wiring layer 7 to the second insulating layer 21), the average value of each is about 60 μm, and the variation in thickness is ± 8 μm.

When the inside of the IVH4 of the double-sided wiring board 9 that had undergone the above-described steps was confirmed with an optical microscope with a magnification of 100, no intra-IVH void G was generated.
In addition, it was confirmed that the thicknesses of the first insulating layer 20 and the second insulating layer 21 in the area where the area ratio of the wiring pattern is small and the area where the area ratio is large are substantially equal.
As described in detail above, the first insulating layer 20 that suppresses generation of the void G in the IVH and has a favorable thickness variation of ± 10 μm or less regardless of the area ratio of the wiring pattern by the above-described steps. It was confirmed that the second insulating layer 21 can be formed.

(Sixth step) [Refer to FIG. 10]
A through hole 29 for electrically connecting a third wiring layer 25 and a fourth wiring layer 26 described later is formed as a through hole at a predetermined position of the double-sided wiring board 9 that has undergone the fifth step.
The through hole 29 can be formed by drilling or laser processing. In the example, the through hole 29 having a diameter of about 0.2 mm was formed by drilling.

Next, a first LVH (Laser Via Hole) 22 for electrically connecting the first wiring layer 6 and the third wiring layer 25 through the first insulating layer 20 is replaced with the double-sided wiring board that has undergone the above-described steps. 9 at predetermined positions. In addition, a second LVH 23 for electrically connecting the second wiring layer 7 and the fourth wiring layer 26 through the second insulating layer 21 is formed at a predetermined position of the double-sided wiring board 9 that has undergone the above-described steps. .
Specifically, the laser irradiated region is irradiated with laser light at predetermined positions of the first insulating layer 20 and the second insulating layer 21 so that the surfaces of the first wiring layer 6 and the second wiring layer 7 are exposed. By removing the first insulating layer 20 and the second insulating layer 21, LVHs 22 and 23 having an opening diameter of about 150 μm are formed. The LVHs 22 and 23 can be formed by laser processing using a carbon dioxide (CO ₂ ) laser or a YAG laser.

  In the embodiment, the LVHs 22 and 23 are formed after the through holes 29 are formed. However, the present invention is not limited to this. For example, the through holes 29 may be formed after the LVHs 22 and 23 are formed.

(Seventh step) [Refer to FIG. 11]
Second plating layers 24 a and 24 b made of, for example, copper are formed on the surfaces of the first insulating layer 20 and the second insulating layer 21 so as to cover the through holes 29 and the inner surfaces of the LVHs 22 and 23. The second plating layers 24a and 24b are formed by performing electroless copper plating and further electrolytic copper plating. In the embodiment, the thickness of the second plating layers 24a and 24b is about 20 μm. Plating conditions were set.
Thereafter, the second plating layers 24a and 24b are selectively etched to form the third wiring layer 25 and the fourth wiring layer 26 so as to obtain predetermined wiring patterns 27a and 27b by photolithography.
The double-sided wiring board 9 that has undergone the above-described steps is referred to as a four-layer wiring board 28.

A solder resist layer is formed on the front and back surfaces of the four-layer wiring board 28 using a roll coating method.
First, an outline of a method for forming a solder resist layer will be described with reference to FIG.
As shown in FIG. 3, the solder resist layer is formed by applying the first solder resist ink 31a on both sides of the four-layer wiring board 28 by the first roll coater 10a used in the third step described above. Then, the second solder resist ink 31b was further used in the above-described fourth step on the third coating step for forming the first resist ink layers 38a and 38b, and on the first resist ink layers 38a and 38b. A fourth application step of applying the second roll coater 10b to form the second resist ink layers 39a and 39b; and the first resist ink layers 38a and 38b and the second resist ink layers 39a and 39b. And a drying step of simultaneously drying.

  The third application step is a step mainly intended to fill the inside of the through hole 29 and the LVHs 22 and 23 with the first solder resist ink 31a while suppressing generation of voids in the through holes and voids in the LVH. The fourth application step is a step mainly intended to set the thickness of solder resist layers 40 and 41, which will be described later, with the second solder resist ink 31b to a predetermined thickness.

  Hereinafter, the third application process will be described as an eighth process, the fourth application process as a ninth process, and the drying process as a tenth process.

(Eighth step) [Refer to FIG. 4 and FIG. 12]: Third application step The third application step uses the first roll coater 10a used in the third step (first application step) described above, When the solder resist ink 31a is applied to both sides of the four-layer wiring board 28, the inside of the through holes 29 and the LVHs 22 and 23 is suppressed by the first solder resist ink 31a from the generation of voids in the through holes and LVH. The purpose is to be filled.

The first solder resist ink 31a is adjusted to have a predetermined viscosity, for example, within a range of 4 to 10 Pa · s, and then supplied to the storage units 14a and 14b of the first roll coater 10a shown in FIG. .
Next, according to a procedure similar to the procedure detailed in the third step (first coating step), as shown in FIG. 12, the first solder resist ink is applied to a predetermined region on the front and back sides of the four-layer wiring board 28. First resist ink layers 38a and 38b made of 31a are formed.
The insides of the through holes 29 and the LVHs 22 and 23 were filled with the first solder resist ink 31a, and it was confirmed that no voids in the through holes and no voids in the LVH were generated.
The reason why no through-hole void has occurred will be described later together with the reason why the IVH void G has not occurred.

  The reason why the LVH internal void did not occur is that the opening widths La and Lb (about 120 μm in the first embodiment) are narrower than the opening diameters (about 150 μm in the embodiment) of the LVHs 22 and 23 which are non-through holes. Therefore, it is considered that the air in the LVHs 22 and 23 was easily removed when the first solder resist ink 31a was applied to the four-layer wiring board 28.

(9th process) [Refer FIG.7 and FIG.13]: 4th application | coating process The 4th application | coating process is 2nd so that the soldering resist layers 40 and 41 mentioned later may become predetermined | prescribed thickness (20 micrometers in an Example). The resist ink layers 39a and 39b are formed to a predetermined thickness.

The second solder resist ink 31b is supplied to the storage units 14c and 14d of the second roll coater 10b shown in FIG. In the example, as the second solder resist ink 31b, the same one as the first solder resist ink 31a used in the third coating step was used.
Next, according to a procedure similar to that detailed in the fourth step (second coating step), the second resist ink layers 38a and 38b of the four-layer wiring board 28 are secondly patterned as shown in FIG. Second resist ink layers 39a and 39b made of the solder resist ink 31b are formed.

Since the uncured first resist ink layers 38a and 38b and the uncured second resist ink layers 39a and 39b are mixed with each other in the vicinity of the interface, it is difficult to clearly check the boundary surface. It is.
Therefore, the total thickness ti, tj of the first resist ink layers 38a, 38b and the second resist ink layers 39a, 39b (thickness from the surface of the third wiring layer 25 to the surface of the second resist ink layer 39a). As a result of measuring the thickness from the surface of the fourth wiring layer 26 to the surface of the second resist ink layer 39b, it was confirmed that the total thicknesses ti and tj were both about 25 μm.

(Tenth Step): Drying Step The four-layer wiring board 28 that has undergone the above-described steps is heated, for example, at 80 ° C. for 20 minutes by using a drying furnace (not shown), whereby the first resist ink layers 38a, 38b and second The solvent in the resist ink layers 39a and 39b is evaporated and dried. The first resist ink layers 38a and 38b and the second resist ink layers 39a and 39b after drying are in an uncured state.

(11th step) [Refer to FIG. 14]
The first resist ink layers 38a and 38b and the second resist ink layers 39a and 39b after drying are subjected to predetermined exposure and development by a photolithography method to form openings 44a and 44b.
Next, the four-layer wiring board 28 in which the openings 44a and 44b are formed is heated at, for example, 150 ° C. for 30 minutes to thereby form the first resist ink layers 38a and 38b and the second resist ink layers 39a and 39b. Is cured. The cured first resist ink layers 38a and 38b and second resist ink layers 39a and 39b become solder resist layers 40 and 41, respectively.

Thickness tk, tm of the solder resist layers 40, 41 (thickness from the surface of the third wiring layer 25 to the surface of the solder resist layer 40, thickness from the surface of the fourth wiring layer 26 to the surface of the solder resist layer 41) ) Was measured, and it was confirmed that the total thickness tk and tm were both about 20 μm.
The solder resist layers 40 and 41 include a first solder resist ink 31a for forming the first resist ink layers 38a and 38b and a second solder ink for forming the second resist ink layers 39a and 39b. Since each main component is the same as that of the solder resist ink 31b, it is a layer having a uniform resin component, and it was confirmed that the surfaces of the solder resist layers 40 and 41 are substantially flat.

  When an electronic component or the like is mounted on a build-up type multilayer printed wiring board having a substantially flat surface of the solder resist layer, the electronic component can be mounted on the printed wiring board with high accuracy. Specifically, when the position reference pattern is formed on the outer layer of the build-up type multilayer printed wiring board and this position reference pattern is recognized by the image recognition unit of the mounting machine for mounting electronic components, the surface of the solder resist layer is Since the recognition image distortion due to light refraction is small when the surface is substantially flat, the recognition accuracy for recognizing the position reference pattern is improved, so that the electronic component can be mounted on the printed wiring board with high accuracy.

  Through the above-described steps, the build-up type multilayer printed wiring board 50 including the four wiring layers (6, 7, 25, 26) in which generation of voids in IVH and voids in through holes is suppressed is obtained.

  Here, the reason why the generation of the void G in the IVH is suppressed will be described with reference to FIG. FIG. 15 shows the first application in the IVH 4 of the double-sided wiring board 9 curved along the outer peripheral surface of the roll 12b by the roller portion 30 of the first roll coater 10a in the first application step (see FIG. 4) of the embodiment. It is typical sectional drawing showing a mode that it fills with the insulating resin ink 11a. Further, (a), (b), and (c) in FIG. 15 show how the double-sided wiring board 9 moves in the direction of the arrow Ed in that order.

As shown in FIG. 15, the area of each contact surface between the pair of rolls 12a and 12b and the double-sided wiring board 9 can be varied by bending the double-sided wiring board 9 along the outer peripheral surface of the roll 12b.
That is, by making the length 150b of the contact surface between the roll 12b and the double-sided wiring board 9 in the transport direction Ed of the double-sided wiring board 9 longer than the length 150a of the contact surface between the roll 12a and the double-sided wiring board 9, The insulating resin ink 11a is first supplied from the roll 12b side and fills the inside of the IVH4. For this reason, since the air inside IVH4 is pushed out to the roll 12a side, it is thought that generation | occurrence | production of the void G in IVH can be suppressed.
Therefore, in order to suppress the generation of the void G in the IVH, the length 150b is made longer than the length 150a so that the inside of the IVH4 is filled with the insulating resin ink 11a supplied from the roll 12b side. Good.

  Further, the reason why the generation of voids in the through holes is suppressed can also be explained for the same reason as the reason why the generation of voids G in the IVH is suppressed.

  Moreover, in the Example, although the double-sided wiring board 9 was curved to the circumferential direction along the surface of the roll 12b, by arrange | positioning the roller part 30 so that the central axis O of the roller part 30 may become the roll 12a side. Even if the double-sided wiring board 9 is curved along the outer peripheral surface of the roll 12a, the same effect, that is, the effect of suppressing the voids in the IVH and the voids in the through hole can be obtained.

  The embodiment of the present invention is not limited to the configuration and procedure described above, and it goes without saying that modifications may be made without departing from the scope of the present invention.

  For example, in the embodiment, the first coating process, the second coating process, and the curing process are described as independent processes, but the present invention is not limited to this. For example, the first roll coater and the second roll The first coating process, the second coating process, and the curing process may be performed continuously using an integrated coating and curing apparatus that includes a coater and a curing (drying) furnace.

  In the embodiment, the third coating process, the fourth coating process, and the drying process are described as independent processes. However, the present invention is not limited to this. For example, the first roll coater and the second roll The third coating process, the fourth coating process, and the drying process may be continuously performed using an integrated coating / drying apparatus including a coater and a drying furnace.

  Moreover, although the Example demonstrated the manufacturing method of the buildup type | mold multilayer printed wiring board which consists of four wiring layers, it is not limited to this. That is, the present invention can achieve the same effect even in a method for manufacturing a build-up type multilayer printed wiring board composed of two or more multilayer wiring layers.

In the embodiment, the first insulating resin ink and the second insulating resin ink are the same resin component. However, the present invention is not limited to this, and different resin components may be used.
Moreover, although the 1st soldering resist ink and the 2nd soldering resist ink were made into the same resin component, it is not limited to this, A different resin component may be sufficient.

In the embodiment, the first insulating resin ink and the second insulating resin ink have the same viscosity. However, the present invention is not limited to this, and may have different viscosities.
By the way, the viscosity of the first insulating resin ink and the second insulating resin ink can be adjusted by changing the solvent volume ratio of the ink. That is, the viscosity can be lowered by increasing the solvent volume ratio, and conversely, the viscosity can be increased by decreasing the solvent volume ratio.
Therefore, by reducing the solvent volume ratio of the first insulating resin ink 11a, the amount of the solvent that evaporates when the first insulating resin ink 11a is cured can be reduced. It is possible to reduce the amount of dents generated on the surface of the insulating layer corresponding to. When a wiring pattern is formed on the surface of an insulating layer having a dent with a large amount of dent, the wiring pattern formed on the dent may be disconnected or a short-circuit defect may occur between the wiring patterns.

  In addition, although leveling property will deteriorate if solvent volume ratio is made small, in the 1st application | coating process, it is the objective to fill the 1st insulating resin ink 11a so that the level | step difference of IVH4 and the wiring pattern 8a may be filled. Therefore, deterioration of leveling property does not become a problem in the first coating process.

Further, when the solvent volume ratio of the first insulating resin ink 11a is reduced, the leveling property of the first insulating resin ink 11a is deteriorated. Therefore, the first insulating resin ink 11a has a first level on the first wiring layer 6 and the second wiring layer 7. If the resin ink layers 18a and 18b are formed thick, the smoothness on the surfaces of the first resin ink layers 18a and 18b may be deteriorated.
Accordingly, as in the embodiment, the first insulating resin ink 11a is filled in the IVH 4 so as to fill the steps of the wiring pattern, and the first wiring layer 6 and the second wiring layer 7 are filled with the first insulating resin 11a. It is desirable to set the coating conditions so that the resin ink layers 18a and 18b are hardly formed.

It is typical sectional drawing for demonstrating the 1st process in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention. It is typical sectional drawing for demonstrating the 2nd process in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention. It is a process flowchart for demonstrating the formation method of the insulating layer and soldering resist layer in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention. It is typical sectional drawing for demonstrating the 3rd process in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention, and is the Example of the manufacturing apparatus of the buildup type multilayer printed wiring board of this invention It is a typical sectional view for explaining. It is typical sectional drawing for demonstrating the 3rd process in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention, and is the Example of the manufacturing apparatus of the buildup type multilayer printed wiring board of this invention It is a typical sectional view for explaining. It is typical sectional drawing for demonstrating the 3rd process in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention. It is typical sectional drawing for demonstrating the 4th process in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention. It is typical sectional drawing for demonstrating the 4th process in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention. It is typical sectional drawing for demonstrating the 5th process in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention. It is typical sectional drawing for demonstrating the 6th process in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention. It is typical sectional drawing for demonstrating the 7th process in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention. It is typical sectional drawing for demonstrating the 8th process in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention. It is typical sectional drawing for demonstrating the 9th process in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention. It is typical sectional drawing for demonstrating the 11th process in the Example of the manufacturing method of the buildup type multilayer printed wiring board of this invention. It is typical sectional drawing for demonstrating the solution reason which suppresses generation | occurrence | production of the void in IVH and the void in a through hole. It is typical sectional drawing for demonstrating the reason why the void in IVH and the void in a through hole generate | occur | produce.

Explanation of symbols

1 core material, 2a, 2b copper foil, 3 double-sided copper-clad plate, 4 IVH, 5a, 5b, 24a, 24b plating layer, 6, 7, 25, 26 wiring layer, 8a, 8b, 27a, 27b wiring pattern, 9 Double-sided wiring board, 10a, 10b roll coater, 11a, 11b insulating resin ink, 12a-12d roll, 13a-13d doctor bar, 14a-14d storage part, 15a, 15b mounting part, 16a-16d roll part, 17a-17d Groove, 18a, 18b, 19a, 19b Resin ink layer, 20, 21 Insulating layer, 22, 23 LVH, 28 Four-layer wiring board, 29 Through hole, 30 Roller part, 31a, 31b Solder resist ink, 38a, 38b, 39a 39b Resist ink layer 40, 41 Solder Dist layer, 44a, 44b opening, 50 build-up type multilayer printed wiring board, La to Ld pitch (opening), Ra to Rd diameter, ta to td depth, θa to θd opening angle, te to tk, tm thickness , O axis, c1 center line

Claims (2)

A double-sided wiring board is prepared in which wiring patterns are formed on both surfaces of a core material having a through-hole and bendable, and the wiring patterns are electrically connected to each other via a conductive layer covering the inner surface of the through-hole. Thereafter, when the double-sided wiring board is conveyed in one direction through a nip opening between a pair of rolls in the roll coater, an insulating ink is respectively applied to both sides of the double-sided wiring board by the roll coater, and the wiring In the manufacturing method of the build-up type multilayer printed wiring board that performs the ink application process of filling the through hole with the insulating ink at the same time as forming the insulating layer covering the pattern,
The ink application step includes
A method of manufacturing a build-up type multilayer printed wiring board, wherein the method is carried out in a state where a part of the double-sided wiring board facing the nip port is aligned with an outer peripheral surface of one roll. A double-sided wiring board is prepared in which wiring patterns are formed on both surfaces of a core material having a through-hole and bendable, and the wiring patterns are electrically connected to each other via a conductive layer covering the inner surface of the through-hole. Then, when the double-sided wiring board is conveyed in one direction and passes through a roll coater, an insulating ink is applied to both sides of the double-sided wiring board by a roll coater to form an insulating layer that covers the wiring pattern. At the same time, in the manufacturing apparatus of a build-up type multilayer printed wiring board that fills the through hole with the insulating ink,
The roll coater
A pair of rolls capable of contacting and separating from each other, a pair of rolls forming a nip opening that allows the double-sided wiring board to pass between the rolls;
Ink supply means for supplying the insulating ink to each of the pair of rolls;
A guide member that sandwiches the double-sided wiring board with one roll upstream of the nip opening when viewed in the one direction and guides the conveyance of the double-sided wiring board; A bending means for bringing the part of the double-sided wiring board to reach the outer peripheral surface of the one roll and bending it along the outer peripheral surface ;
An apparatus for manufacturing a build-up type multilayer printed wiring board, comprising: a conveying means for conveying the wiring core material in the one direction in cooperation with rotational driving of the pair of rolls.

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