JPH10173337A - Production of printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a fine pitch, while eliminating side etching by forming a plating layer on the surface of a plate barrier layer and the inner surface of a through-hole, filling the through-hole with a mask material, removing the plate barrier layer to expose a conductor layer and then forming a specified pattern thereon. SOLUTION: First, a conductive mask 2 is pasted to a both side copper clad plate, i.e., a conductor layer CO. A resin layer of the conductive mask 2 is mounted on a printed board 1 and bonded thereto by baking before a through-hole is made at a specified position of the printed board 1. Subsequently, the printed board 1 is immersed into a plating layer and subjected to electrolytic plating using the conductor layer as an electrode. Thereafter, the through-hole TH 10 is filled with a resin paste, and the plating layer on the surface and rear of the printed board 1 is stripped from the conductive layer of the conductive mask 2 by etching. The printed board 1 is coated, on the surface and rear thereof, with an etching resist which is then exposed and developed and the conductive layer CO is etched, thus forming a pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a printed circuit board, and more particularly to a method of manufacturing a fine pitch printed circuit board having through holes. The pattern on the surface of the printed circuit board is formed by etching a conductor layer on the surface of the printed circuit board. In particular, the pattern size of the printed circuit board for fine pitch is, for example, a line width of 90
μ, the gap is 90 μ, which is delicate and dense. As described above, when etching a fine and fine pattern for fine pitch, side etching tends to occur as the pattern thickness increases. Therefore, the thickness of the pattern layer is required to be equal to or less than a predetermined thickness.

[0002]

[Prior art]

<Prior Art 1> Prior Art 1 will be described with reference to the drawings.
FIG. 17 to FIG. 21 are views for explaining a manufacturing process of a printed board with through holes. First, a hole making process is performed on the printed circuit board. As disclosed in FIG. 17, the printed circuit board 1 is a double-sided copper-clad board in which a conductor layer CO such as copper is bonded on both sides. A through hole is provided at a predetermined position of the printed circuit board 1 with a lathe or the like.

Next, plating is performed on the printed circuit board. As shown in FIG. 18, the printed circuit board 1 is immersed in a plating bath and subjected to electrolytic plating. Therefore, the plating layer M10 is also formed on the front and back of the printed circuit board 1 and the inner wall of the through hole. As a result, a through hole TH10 is formed. Subsequently, a hole filling process is performed on the printed circuit board. As shown in FIG.
H10 is filled with a paste resin mask MK using a roll coater or the like. Thereafter, the mask MK is thermally cured.

Further, a pattern forming process is performed on the printed circuit board. As disclosed in FIG. 20, an etching resist is applied on the front and back surfaces of the printed circuit board 1 by a screen printing method or the like. After that, the etching resist is exposed and developed to form a conductor layer C.
O is etched. Thereafter, the etching resist is removed to obtain a pattern as shown in FIG.

[0005] Finally, a mask removal process is performed on the printed circuit board. As shown in FIG. 21, the through hole TH1
The mask MK in 0 is removed by chemical treatment with caustic soda or the like. In the above-mentioned manufacturing method, when forming a through hole in the printed circuit board 1, a plating layer is also formed on the surface of the conductor layer CO. Therefore, when forming a pattern, the plating layer is etched in addition to the conductor layer, and side etching becomes a problem. <Prior art 2> As a technique which does not increase the thickness of the surface of the printed circuit board 1 unlike the prior art 1, Japanese Patent Application Laid-Open No. 63-23 / 1988
No. 2487 discloses a method for manufacturing a printed wiring board.

According to this method, an insulating mask made of a thermoplastic resin such as polyethylene, polypropylene, polyvinyl chloride, or vinylidene is coated on a copper foil on the surface of a printed circuit board. After the through holes are formed, the surface of the printed circuit board is electrolytically plated to form through holes. Thereafter, a resin is embedded in the through hole. Then, the mask is mechanically peeled off. Further, a pattern is provided on the surface of the printed circuit board. Thereafter, the resin in the through hole is removed. The pattern is formed on the surface of the printed circuit board by the above steps.

[0007]

As described above, the printed circuit board 1 according to the prior art 1 has to etch the conductor layer and the plating layer. Therefore, side etching becomes a problem. For this purpose, mechanical polishing of a plating layer formed on the surface of a printed circuit board may be considered. However, a pattern surface having a uniform thickness cannot be obtained by the mechanical polishing method. It also required a lot of man-hours.

The above prior art 2 which proposes a method for preventing side etching does not occur. In the prior art 2, the printed wiring board is covered with an insulating resin such as polyvinyl chloride, vinylidene or the like on the entire front and back surfaces thereof. A uniform charge cannot be applied to the entire surface. As a result, plating with a uniform thickness is not formed on the inner wall of the through hole. SUMMARY OF THE INVENTION An object of the present invention is to provide a manufacturing method capable of obtaining a fine pitch pattern without side etching even when a uniform thickness plating is formed on the inner surface of a through hole of a printed circuit board without increasing the thickness of a conductor layer to be patterned. Is provided.

[0009]

The object of the present invention is to form a plating having a uniform thickness on the inner wall of a through hole without forming a plating layer on a pattern forming surface. In the described invention, a step of laminating a plating barrier layer made of a material different from a material of the conductor layer on at least one conductor layer of a printed board having conductor layers on both surfaces, and a step of forming a through hole in the printed board And providing a plating layer on the inner surface of the through hole including the surface of the plating barrier layer to form a through hole, and filling the through hole with a mask material,
A method of manufacturing a printed circuit board, comprising: removing the plating barrier layer to expose the conductor layer; and forming a predetermined pattern on the exposed conductor layer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 An embodiment of the present invention will be described with reference to the drawings. The same parts as those in the conventional example are denoted by the same reference numerals and description thereof will be omitted. First, the first method of the manufacturing method according to the present invention is described.
In the third step, as shown in FIG. 1, the conductive mask 2 is attached to the conductive layer CO which is a double-sided copper-clad plate described in the conventional example.

As the conductive mask 2, a plating barrier material made of a material different from the material of the conductor layer CO may be used. In the first embodiment, for example, Noritsuki Haku, MK-61 manufactured by Mitsui Kinzoku Co., Ltd. using resin and copper foil is used.
The shape is about 55 cm in width W × about 100 cm in length L. It is composed of upper and lower layers. The lower layer is a resin layer 21 such as a phenol resin and has a thickness of about 30 μm. The upper layer is a conductive layer 22 such as a copper foil and has a thickness of about 35 μm. The resin layer 21 of the conductive mask body 2 is placed on the printed circuit board 1 and baked and bonded at 120 ° C. to 130 ° C. for 5 minutes to 10 minutes. After the baking bonding, a through hole is opened at a predetermined position of the printed circuit board 1 with a lathe or the like.

Next, plating is performed on the printed circuit board. As shown in FIG. 2, the printed circuit board 1 is immersed in a plating bath and electrolytic plating is performed using the conductive layer 22 as an electrode. Therefore, a plating layer M10 having a uniform thickness is formed on the surface of the conductive mask body 2 and the inner wall of the through hole. Subsequently, a hole filling process is performed on the printed circuit board. As shown in FIG. 3, a paste resin mask MK is filled in the through hole TH10 using a roll coater or the like. As the mask MK, Plus Fine, PTR924W manufactured by Kureo Chemical Co., Ltd. was used.
Thereafter, the mask MK is light-cured.

Further, a process for exposing the conductor layer to the printed board is performed. That is, as shown in FIG. 4, the plating layer 10 on the front and back of the printed circuit board 1 and the conductive layer 22 of the conductive mask 2 are separated by etching. When the conductive mask body 2 uses a metal different from the material of the conductive layer CO, for example, Cr, the etching process may be performed by selecting an etching solution.
Therefore, the resin layer 21 of the conductor mask 2 is exposed on the front and back of the printed circuit board 1. Then, the resin layer 21 is separated by swelling treatment with hydrochloric acid or the like.

Next, a pattern forming process is performed on the printed circuit board. As disclosed in FIG. 5, an etching resist is applied on the front and back surfaces of the printed circuit board 1 by photo printing using a dry film photoresist or the like. Thereafter, the etching resist is exposed and developed, and the conductor layer CO is etched. Thereafter, the pattern is obtained by removing the etching resist. Finally, a mask removal process is performed on the printed circuit board.
That is, as shown in FIG. 6, the mask MK in the through hole TH10 is removed by chemical treatment with caustic soda or the like.

In the above embodiment, the method of attaching the conductive mask 2 to the conductor layers CO on both sides of the printed circuit board 1 has been described. However, the conductive mask body 2 may be attached to at least one conductive layer CO of the printed circuit board 1. This is the case where only one surface of the printed circuit board 1 has a high density for fine pitch and the other has a low density of the power and ground patterns. <Embodiment 2> In the embodiment 1, the conductor mask 2 including the bonding portion 21 and the copper foil layer 22 was used.
A conductor copper foil may be provided after applying an adhesive such as a phenol resin on the first conductor layer CO. <Embodiment 3> FIGS. 7A and 7B show printed board members 8, 9 and 10 as examples used for manufacturing a multilayer printed board.

The printed board member 8 is used in the first or second embodiment.
A predetermined pattern is provided on the conductor layers CO on both surfaces, and the pattern surface is plated with copper. Then, through holes for conducting the patterns on both sides are provided at predetermined positions. The printed board member 9 has a predetermined pattern on the conductor layers CO on both surfaces. However, the conductor layer CO is not plated. The printed board member 10 is provided with a pattern at a predetermined position on one surface and is plated with copper. The pattern forming portion L in which the entire surface of the conductor layer CO on the other surface is copper-plated
A. A through hole is provided at a predetermined position.

FIG. 8 shows printed board members 11, 12, and 13 used for manufacturing a multilayer printed board. The printed board member 11 is manufactured in the same manner as the printed board member 10.
The printed board member 12 is manufactured in the same manner as the printed board member 9. The printed board member 13 is manufactured in the same manner as the printed board member 8.

Hereinafter, a method of manufacturing the multilayer printed board 30 using the printed board members 11, 12, 13 will be described. The multilayer printed board 40 using the printed board members 8, 9, 10 is similarly manufactured separately. You. Next, a lamination process of each of the printed boards is performed. As shown in FIG. 9, the printed board 30 is composed of the conductive mask 2 and the printed board member 1.
The sheets 1, 12, 13 and the copper foil CP are laminated with the adhesive prepreg PP interposed therebetween, and the positions of the patterns of the printed board members 11, 12, 13 are aligned. That is, from below, the copper foil CP, the prepreg PP, the printed board member 13,
Prepreg PP, printed board member 12, prepreg P
P, the printed board member 11, and the conductive mask body 2 are laminated in this order. And 5 minutes to 10 at 120 ° C to 130 ° C
It was baked for a minute and cured. The copper foil CP functions as an electrode plate when plating a printed board 30 described later.

Subsequently, the printed board is perforated and plated. As shown in FIG. 10, a through hole is provided at a predetermined position of the printed board 30, and the printed board 30 is immersed in a plating tank to perform electroplating. Therefore, the surface of the conductive mask body 2 and
A plating layer M10 is formed on the surface of the copper foil CP and on the inner wall of the through hole. As a result, a through hole TH10 is formed.

Further, a hole filling process is performed on the printed board. As shown in FIG. 11, as in the prior art 1, the resin is thermally cured after filling the through hole TH10 with a mask MK such as a resin. Thereafter, the plating layer M10 and the copper foil CP under the printed board 30 are removed by etching. Next, the printed circuit board is laminated. The printed board 3 described with reference to FIGS. 9 to 11 as disclosed in FIG.
No. 0 and a separately manufactured printed board 40 are vertically stacked. However, the masks MK in the through holes TH10 are removed by chemical treatment with caustic soda or the like before the printed boards 30 and 40 are laminated. Pattern forming portion L of printed board member 11 on the uppermost layer of printed board 30
A is directed upward, the pattern forming portion LA of the lowermost printed circuit board member 10 of the printed circuit board 40 is directed downward, and the printed circuit boards 30 and 40 are laminated via a prepreg PP. Thereafter, it was baked and cured at 120 ° C. to 130 ° C. for 5 minutes to 10 minutes.

Next, the printed circuit board is subjected to perforation and plating. As shown in FIG. 13, a through hole TH11 is formed at a predetermined position on the printed circuit board 1. After that, the printed circuit board 1
Is immersed in a plating tank to perform electrolytic plating. Therefore, the plating layer M11 is also formed on the front and back of the printed circuit board 1 and the inner wall of the through hole TH11.
Is formed. Therefore, a through hole TH11 is formed.

Subsequently, a process for exposing the conductive layer on the printed circuit board is performed. As disclosed in FIG. 14, the plating layers 11, the plating layers 10 on the front and back surfaces of the printed circuit board 1 and the conductive layer 22 of the conductive mask body 2 are separated by etching. Therefore, the resin layer 21 of the conductor mask 2 is exposed on the front and back of the printed circuit board 1. Further, a process of removing the resin layer from the printed circuit board is performed. As shown in FIG. 15, the resin layer 21 of the conductor mask 2 on the front and back of the printed circuit board 1 is swelled with hydrochloric acid or the like and peeled off.

Next, reinforcing plating is performed to increase the bonding strength of the plating. In particular, this is for preventing the peeling of the plating at the corners of the through holes, and this reinforcing plating may be performed as needed. As a result, only the pattern forming portion LA exists on the front and back of the printed circuit board 1. However, FIG. 15 shows the reinforcing plating layer M12 for easy understanding of the description.

Finally, a process for forming a pattern on the printed circuit board is performed. As shown in FIG. 16, an etching resist is applied on the front and back surfaces of the printed circuit board 1 by using a screen printing method as in the prior art 1. After that, the etching resist is exposed and developed, and the conductor layer CO is etched.
Thereafter, the etching resist is removed to obtain a pattern as shown in FIG. After that, the through hole TH of the printed circuit board 1
The mask MK in 11 is removed.

[0025]

As described above, the printed circuit board manufactured by the manufacturing method according to the present invention does not increase the thickness of the conductor layer for pattern formation even if plating of uniform thickness is formed on the inner surface of the through hole. Therefore, a fine pitch pattern without side etching can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a hole forming step of a printed circuit board according to the present invention,

FIG. 2 is an explanatory view of a plating step of a printed circuit board according to the present invention,

FIG. 3 is an explanatory view of a hole filling step of a printed board according to the present invention;

FIG. 4 is an explanatory view of a step of exposing a conductor layer of a printed board according to the present invention,

FIG. 5 is an explanatory view of a printed circuit board pattern forming step according to the present invention;

FIG. 6 is an explanatory diagram of a mask removing step of a printed circuit board according to the present invention;

FIG. 7 is an explanatory view of a printed board member for a printed board;

FIG. 8 is an explanatory view of a printed board member for a printed board;

FIG. 9 is an explanatory view of a printed board laminating step according to the present invention;

FIG. 10 is an explanatory view of a hole forming and plating step of a printed board according to the present invention;

FIG. 11 is an explanatory view of a hole filling step of a printed board according to the present invention,

FIG. 12 is an explanatory view of a step of laminating a printed circuit board according to the present invention,

FIG. 13 is an explanatory diagram of a hole forming and plating step of a printed circuit board according to the present invention,

FIG. 14 is an explanatory view of a step of exposing a conductor layer of a printed board according to the present invention;

FIG. 15 is an explanatory view of a resin layer removing step of a printed board according to the present invention;

FIG. 16 is an explanatory view of a printed circuit board pattern forming step according to the present invention;

FIG. 17 is an explanatory view of a conventional process of forming a hole in a printed circuit board;

FIG. 18 is an explanatory view of a conventional printed circuit board plating process,

FIG. 19 is an explanatory view of a conventional printed circuit board hole filling step,

FIG. 20 is an explanatory view of a conventional printed circuit board pattern forming process;

FIG. 21 is an explanatory diagram of a conventional mask removal process for a printed circuit board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed board 2 Conductive mask body 21 Adhesion part 22 Conductive layer 3 Printed board 4 Printed board 5 Printed board member 10 Printed board member 30 Printed board 40 Printed board PP adhesive MK Mask TH10 Through hole CP Copper foil M1 Plating layer M11 Plating layer M12 Reinforcement plating layer LD pattern LA Pattern forming part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Keizo Yamamoto, Inventor 4-1-1, Uedanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Yasutomo Maehara 4-chome, Ueodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture No. 1 in Fujitsu Limited

Claims (1)

[Claims] 1. A step of laminating a plating barrier layer made of a material different from a material of a conductive layer on at least one conductive layer of a printed circuit board having a conductive layer on both sides, and a step of forming a through hole in the printed board. Providing a plating layer on the inner surface of the through hole including the surface of the plating barrier layer to form a through hole; filling the through hole with a mask material; removing the plating barrier layer to form the conductor layer And a step of forming a predetermined pattern on the exposed conductor layer.