JP2015216300A - Printed wiring board manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board manufacturing method which can form a halved through hole simply and easily regardless of a thickness of the printed wiring board and a hole diameter of a through hole.SOLUTION: A manufacturing method of a printed wiring board having a through hole halved in a circumferential direction by a slit extending in an axial direction comprises: a process of forming a through hole 18 in a substrate; a process of forming a cylindrical plating layer 8 on an inner surface of the through hole 18; a process of filling the inner peripheral side of the cylindrical plating layer 8 with protection resin 22; a process of irradiating laser beams on the resin 22 which faces a position where a slit is to be formed to remove part of the resin 22 to expose an inner surface of the plating layer 8 on a place where the slit is to be formed; a process of removing the plating layer 8 exposed by the removal of part of the resin 22 by etching to form a slit; and a process of removing all of the resin 22 filled in on the inner peripheral side of the plating layer 8.

Description

  The present invention relates to a method for manufacturing a printed wiring board.

In a multilayer printed wiring board or the like, a through hole may be formed to connect each layer. The through hole has a plating layer formed on the inner side surface of the hole, and is provided through the printed wiring board in the thickness direction. Such a through hole is provided with lands extending on the front and back surfaces of a printed wiring board or the like. This land is electrically connected to the plating layer on the inner surface described above. The printed wiring board is formed in a sheet shape having a plurality of pieces, and each piece is often divided later.
However, since the printed wiring board requires a relatively large space for forming the above-described through hole, the number of pieces to be taken has been reduced.
Patent Document 1 proposes a technique for forming a half through hole on an end face of a printed wiring board. By forming such a half through hole, the installation space can be reduced compared with a general circular through hole, and the reduction in the number can be suppressed.

JP 2000-082662 A

  By the way, when forming the above-mentioned half through-hole, if the through-hole formed in a circle is cut in half, a burr may occur in the plating layer. For this reason, an increase in man-hours related to burr removal and a man-hour related to burr inspection increase. In order to suppress the occurrence of such burrs, for example, it is conceivable to remove the plating layer where the through hole is to be cut by etching or the like in advance. is there. However, when exposing the inner surface of the through hole, it is necessary to apply light obliquely or to incline the printed wiring board, which makes the operation complicated. In addition, when the thickness of the printed wiring board on which the through hole is formed is large, or when trying to reduce the hole diameter of the through hole, the light does not reach the inner surface of the through hole, and an exposure process using a photoresist is performed. There is a problem that it becomes difficult.

  The present invention has been made in view of the above circumstances, and a printed wiring board manufacturing method capable of easily and easily forming a half through hole regardless of the thickness of the printed wiring board and the hole diameter of the through hole. The purpose is to provide.

In order to solve the above problems, the following configuration is adopted.
A method for manufacturing a printed wiring board according to the present invention is a method for manufacturing a printed wiring board having a through hole divided in a circumferential direction by a slit extending in an axial direction, the step of forming a through hole in a substrate, and the penetration A step of forming a cylindrical plating layer on the inner surface of the hole, a step of filling a protective resin on the inner peripheral side of the cylindrical plating layer, and the resin facing the position where the slit is formed A step of exposing the inner surface of the plating layer where the slit is formed by removing a part of the resin by irradiating a laser beam, and the plating layer exposed by removing a part of the resin Are removed by an etching process to form the slit, and a process of removing all of the resin filled on the inner peripheral side of the plating layer is included.
By doing so, the protective resin can be penetrated and removed in the axial direction with a uniform width by irradiation with laser light having high coherence, so that the inner surface of the plating layer where the slit is formed is exposed with the slit width. Can be made. Therefore, the slit can be easily formed by the etching process. Therefore, regardless of the thickness of the printed wiring board and the hole diameter of the through hole, the half through hole can be formed easily and easily.

Furthermore, in the method for manufacturing a printed wiring board according to the present invention, the laser beam in the method for manufacturing a printed wiring board may be a laser beam of a carbon dioxide gas laser.
By using a carbon dioxide laser, it is possible to easily obtain a high-power laser beam necessary for removing the protective resin.

Furthermore, in the method for manufacturing a printed wiring board according to the present invention, the slits in the method for manufacturing a printed wiring board may be formed at two locations, and each slit may be formed at a symmetrical position across the axis. .
By configuring in this way, for example, the substrate is cut so as to pass through two slits arranged at symmetrical positions across the axis, whereby a half-through hole can be formed in the end face of the printed wiring board. .

  According to the method for manufacturing a printed wiring board according to the present invention, it is possible to easily and easily form a half through hole regardless of the thickness of the printed wiring board and the hole diameter of the through hole.

It is sectional drawing which shows the state which formed the hole for IVH (Interstitial Via Hole) in the core board | substrate of the printed wiring board in this embodiment. It is sectional drawing which shows the state which formed the plating layer in the inner surface of IVH in this embodiment. It is sectional drawing which shows the state which laminated-pressed the insulating resin layer and the copper foil on the core board | substrate in this embodiment. It is sectional drawing which shows the state which formed the via hole in the insulating resin layer of this embodiment. It is sectional drawing which shows the state which formed the hole for through-holes which penetrates the insulating resin layer and core substrate of this embodiment. It is sectional drawing which shows the state which formed the plating layer in the inner surface of the hole for via holes and through-holes in this embodiment, and formed the resist and gold plating. It is sectional drawing which shows the state which carried out the dicer cut of the printed wiring board in this embodiment along the slit of a through hole. It is a perspective view of the half through hole in this embodiment. It is a top view of the through-hole in this embodiment. It is a top view which shows the state which filled the protective resin in the through-hole in this embodiment. It is a top view which shows the state after irradiating the protection resin in this embodiment with a laser beam. It is a top view of the through hole in this embodiment.

Hereinafter, a method for manufacturing a printed wiring board according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a state in which IVH (Interstitial Via Hole) holes are formed in the core substrate of the printed wiring board in this embodiment. FIG. 2 is a cross-sectional view showing a state in which a plating layer is formed on the inner surface of the IVH in this embodiment. FIG. 3 is a cross-sectional view showing a state in which an insulating resin layer and a copper foil are laminated and pressed on the core substrate in this embodiment. FIG. 4 is a cross-sectional view showing a state where via holes are formed in the insulating resin layer of this embodiment. FIG. 5 is a cross-sectional view showing a state in which holes for through holes penetrating the insulating resin layer and the core substrate of this embodiment are formed. FIG. 6 is a cross-sectional view showing a state in which a plating layer is formed on the inner surfaces of via holes and through-holes in this embodiment to form a resist and gold plating. FIG. 7 is a cross-sectional view showing a state in which the printed wiring board according to this embodiment is cut by a dicer along the slit of the through hole. FIG. 8 is a perspective view of the half through-hole in this embodiment.

A multilayer printed wiring board 100 shown in FIG. 7 has an inner core substrate 110 and an insulating resin layer 120. The multilayer printed wiring board 100 is formed with a via 10 and a half through hole 30.
The inner core substrate 110 has wirings 2 formed on both surfaces of the electrically insulating resin layer 1.
The insulating resin layer 120 is laminated on both sides of the inner layer core substrate 110. The insulating resin layer 120 has wiring 4 on the outer surface 3 opposite to the inner layer core substrate 110 side.

  The via 10 is a non-through hole that reaches the wiring 2 of the inner core substrate 110 from the outer surface 3 of the insulating resin layer 120. A via wiring portion 6 made of a copper plating layer is formed on the inner surface of the via 10. The via wiring portion 6 electrically connects the wiring 2 of the inner core substrate 110 and the wiring 4 of the outer surface 3 of the insulating resin layer 120.

  The half through hole 30 is formed at the edge 7 of the multilayer printed wiring board 100. As shown in FIGS. 7 and 8, the half through-hole 30 is formed in a round groove shape with a semicircular cross section extending from the outer surface 3 of one insulating resin layer 120 to the outer surface 3 of the other insulating resin layer 120. . A through hole wiring portion 8 made of a copper plating layer is formed on the inner surface of the half through hole 30. Further, the half through-hole 30 has a portion where the through-hole wiring portion 8 is not formed on the edge 7 side. The through-hole wiring part 8 electrically connects each wiring 4 of the two insulating resin layers 120 and the wiring 2 of the inner layer core substrate 110.

The multilayer printed wiring board 100 in this embodiment has the above-described configuration. Next, the manufacturing method of the multilayer printed wiring board mentioned above is demonstrated, referring drawings.
First, as shown in FIG. 1, the through hole 12 is formed in the copper clad laminate 111. The copper clad laminate 111 is formed by depositing copper foil 11 on both surfaces of a resin layer 1 made of an electrically insulating resin material such as glass epoxy resin. For example, MCL-E-679F (manufactured by Hitachi Chemical Co., Ltd.) or the like can be used for the resin layer 1.

Further, as shown in FIG. 2, a copper plating layer 13 is formed on the entire surface of the resin layer 1 including the inner surface of the through hole 12 by a panel plating method or the like.
Next, the wiring 2 is formed by patterning the copper plating layer 13 on the front and back surfaces of the resin layer 1 by a circuit forming process including formation of an etching resist such as a dry film, etching, and removal of the etching resist. Here, as a dry film mentioned above, PH-3030 (made by Hitachi Chemical Co., Ltd.) can be used, for example.
After that, the inner layer core substrate 110 is subjected to a roughening process for forming minute irregularities on the surface by an MD process or the like.

  Next, as shown in FIG. 3, the insulating resin layer 120 and the copper foil 14 are sequentially stacked on the front and back surfaces of the inner layer core substrate 110, and are pressurized and heated. Thereby, the laminated substrate 112 with a copper foil in which the insulating resin layer 120 and the copper foil 14 are integrated with the inner layer core substrate 110 is obtained. Here, as the insulating resin layer 120, for example, GEA-679F (manufactured by Hitachi Chemical Co., Ltd.) can be used.

Next, as shown in FIG. 4, the via hole 16 is processed in the insulating resin layer 120 of the laminated substrate 112 with copper foil. The via hole 16 is formed by laser processing using a carbon dioxide laser, for example. The via hole 16 is formed so as to reach the wiring 2 of the inner core substrate 110 from the outer surface 17 side of the insulating resin layer 120.
Further, as shown in FIG. 5, similarly to the via hole 16, the through hole 18 for the through hole is formed so as to penetrate the two insulating resin layers 120 of the laminated substrate 112 with the copper foil and the inner layer core substrate 110. To do.

Thereafter, desmear treatment is performed to remove the resin residue. This desmear process is performed by bringing the desmear solution into contact with the entire surface of the laminated substrate 112 with the copper foil.
Next, a copper plating layer is formed on the entire surface of the multilayer substrate 112 with a copper foil by a panel plating method. Thereby, the via wiring portion 6 and the through-hole wiring portion 8 are formed on the inner surface of the via hole 16 and the inner surface of the through hole 18. Thereafter, the through hole 18 is filled with a protective resin, the details of which will be described later, and laser processing is performed.

  Further, as shown in FIG. 6, the outer surface 3 of the insulating resin layer 120 is etched to form the wiring 4. Here, the etching process is performed, for example, after masking with an etching resist such as a photosensitive dry film and exposing and removing the circuit pattern. Thereby, the wiring 4 is formed. Then, after removing the dry film and the protective resin and applying the resist 19, gold plating is formed on the portion where the copper plating is exposed.

  The multilayer printed wiring board 100 formed in this way is divided into a plurality of pieces by dicer cutting along a slit (a slit portion 24 described later) of the through hole 20 after shipment. Thereby, the half through-hole 30 (refer FIG. 8) of a cross-sectional semicircle shape is formed between pieces.

Next, the process of forming the above-described through hole 20 will be described in detail with reference to the drawings.
FIG. 9 is a plan view of the through hole in this embodiment. FIG. 10 is a plan view showing a state in which the through hole in this embodiment is filled with a protective resin. FIG. 11 is a plan view showing a state after the protective resin in this embodiment is irradiated with laser light. FIG. 12 is a plan view of the through hole in this embodiment.

First, as shown in FIG. 9, after forming the through-hole 18 in the laminated substrate 112 with a copper foil, a plating layer is formed on the entire surface by a panel plating method. Thereby, a cylindrical through-hole wiring portion 8 is formed inside the through hole 18.
Next, as shown in FIG. 10, the through hole 18 is filled with a protective resin 22 serving as an etching resist. This resin 22 covers the entire inner surface of the through hole 18. Here, as the resin 22, SER-451B (manufactured by Yamaei Chemical Co., Ltd.), which is an alkali-dissolving hole filling ink, can be used.

  Thereafter, as shown in FIG. 11, the resin 22 is irradiated with laser light to form a laser through hole 23 in the resin 22. The laser beam in this embodiment is a laser beam emitted from a carbon dioxide laser. The irradiation width of this laser light is the same as or smaller than the slit width to be formed. The laser light travels straight along the axis of the through hole 18 and penetrates the resin 22 so as to slightly contact the inner surface of the through hole 18. The laser beam is irradiated to a symmetrical position across the axis of the laser through hole 23. Further, the irradiation position of the laser light is on a cut line 21 that is cut by a dicer cut or the like. Here, the higher the output of the carbon dioxide laser, the better. In addition, when the laser beam of the carbon dioxide laser is a pulsed laser beam, when the laser through hole 23 cannot be formed by a single irradiation, the beam is shifted little by little to form the laser through hole 23. What is necessary is just to irradiate so that it may overlap.

  Next, the above-described dry film mask is applied to perform etching. Thereafter, the dry film and the resin 22 are removed with an alkaline solution. Thereby, as shown in FIG. 12, the slit part 24 in which the plating layer is not formed is formed on the cut line 21. In addition, two semicircular arc-shaped lands 25 facing each other are formed on the outer surface 17 side. The slit part 24 extends to the land 25. The slit portion 24 is formed along the axis on the inner surface of the through hole 20.

  Therefore, according to the method for manufacturing a printed wiring board of the above-described embodiment, the protective resin 22 can be penetrated and removed at a uniform width in the axial direction by irradiation with laser light having high coherence. The inner surface of the plating layer at the place to be formed can be exposed with the width of the slit portion 24. Therefore, the slit part 24 can be easily formed by an etching process. As a result, regardless of the thickness of the multilayer printed wiring board 100 and the hole diameter of the through hole 20, the half through hole 30 can be formed easily and easily.

In addition, by using a carbon dioxide laser, it is possible to easily obtain a high-power laser beam necessary for removing the protective resin.
Further, by cutting the multilayer printed wiring board 100 so as to pass through the two slits 24 arranged at symmetrical positions across the axis, the half through-hole 30 can be formed on the end face of the multilayer printed wiring board. Moreover, since the plating layer is not cut by cutting so as to pass through the slit 24, generation of burrs can be suppressed.

  Note that the present invention is not limited to the above-described embodiments, and includes various modifications made to the above-described embodiments without departing from the spirit of the present invention. That is, the specific shapes, configurations, and the like given in the embodiment are merely examples, and can be changed as appropriate.

  For example, in the above-described embodiment, the case where a carbon dioxide laser is used has been described as an example. However, any laser device capable of forming the through hole 18 in the resin 22 may be used, and a laser device other than a carbon dioxide laser may be used.

  Furthermore, in the above-described embodiment, the direction in which the laser beam is irradiated is not particularly defined. However, the irradiation may be performed from one side of the through hole 20 in the axial direction or from both sides. Moreover, although the case where the cross-sectional shape of the laser through-hole 23 formed with a laser beam was a rectangle was illustrated in embodiment mentioned above, the cross-sectional shape of the laser through-hole 23 is not restricted to a rectangle.

  Furthermore, in the embodiment, the multilayer printed wiring board 100 has been described as an example, but the present invention is not limited to a multilayer printed wiring board.

DESCRIPTION OF SYMBOLS 1 Resin layer 2 Wiring 3 Outer surface 4 Wiring 5 Inner surface 6 Via wiring part 7 Edge 8 Through-hole wiring part (plating layer)
DESCRIPTION OF SYMBOLS 10 Via 11 Copper foil 12 Through-hole 13 Copper plating layer 14 Copper foil 16 Via hole 17 Outer surface 18 Through-hole 19 Resist 20 Through-hole 22 Resin 23 Laser through-hole 24 Slit part (slit)
30 Half-thru hole 100 Multilayer printed wiring board (printed wiring board)
DESCRIPTION OF SYMBOLS 110 Inner layer core board | substrate 120 Insulating resin layer 111 Copper clad laminated board 112 Laminated board with copper foil

Claims (3)

A method of manufacturing a printed wiring board having a through hole divided in a circumferential direction by a slit extending in an axial direction,
Forming a through hole in the substrate;
Forming a cylindrical plating layer on the inner surface of the through hole;
Filling a protective resin on the inner peripheral side of the cylindrical plating layer;
Irradiating a laser beam to the resin facing the position where the slit is formed, and exposing the inner surface of the plating layer where the slit is formed by removing a part of the resin;
Removing the plating layer exposed by removing a portion of the resin by etching to form the slit;
Removing all of the resin filled on the inner peripheral side of the plating layer.   The method for manufacturing a printed wiring board according to claim 1, wherein the laser beam is a laser beam of a carbon dioxide gas laser.   The method for manufacturing a printed wiring board according to claim 1, wherein the slit is formed at two locations, and each slit is formed at a symmetrical position across the axis.

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