JP2022091223A - Manufacturing method of print circuit board and print circuit board - Google Patents

Abstract

To obtain an excellent conductive circuit on a penetration hole.SOLUTION: A manufacturing method contains the steps of: preparing a double-sided copper adhesion laminate sheet 3 made of an insulation substrate 1 and, a first copper foil 2-1 and a second copper foil 2-2, formed on both surfaces; forming a penetration hole 4 to the double-sided copper adhesion laminate sheet; forming a cylindrical through-hole conductor 5-3 to a side wall of the penetration hole; forming both of a first plating film 5-1 onto the first copper foil 2-1, and a second plating film 5-2 onto the second copper foil 2-2 to fill a filling resin 6 to the penetration hole, removing the first copper foil and the first plating film, the second copper foil and the second plating film, and the filling resin projected from the penetration hole to obtain one surface of a front surface of the insulation substrate and the front surface of the filling resin to have a shape of both end parts of the through-hole conductor, which is inserted into the penetration hole from the front surface having the one surface of the insulation substrate and the filling resin in a convex shape; forming a third plating film 7-1 and a fourth plating film 7-2, onto the front surface of the insulation substrate and the front surface of the filling resin as one surface; and forming a first conductive circuit 8-1 and a second surface circuit 8-2 on both front surfaces of the insulation substrate from the third plating film 7-1 and the fourth plating film 7-2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing a printed wiring board having through holes and a printed wiring board.

Conventionally, a printed wiring board having a through hole formed has been used (see, for example, Patent Document 1). 4 (a) to 4 (d) are diagrams showing an embodiment of a conventional method for manufacturing a printed wiring board having a through hole formed therein.

The printed wiring board is manufactured by the following process. First, a through hole 54 is formed by a drill in a double-sided copper-plated laminated plate 53 composed of an insulating substrate 51 and copper foils 52 formed on both surfaces thereof, and a tubular through-hole conductor 55 is formed on the exposed insulating substrate 51. , A plating film 59 is formed on the copper foil 52 (FIG. 4A). Next, the through-hole conductor 55 is filled with the filling resin 56, and the filling resin 56 is polished so as to be flush with the through-hole conductor 55 and the plating film 59 (FIG. 4B). Next, the plating film 57 is formed on both surfaces where the filling resin 56, the through-hole conductor 55, and the plating film 59 are flush with each other (FIG. 4 (c)). Further, for example, a subtractive method is applied to the plating film 57 to form a conductor circuit 58 (FIG. 4 (d)).

Japanese Patent Application Laid-Open No. 2003-163452

In the printed wiring board manufactured by the above-mentioned manufacturing method, the filling resin 56 protrudes from the surface of the insulating substrate 51 by the thickness of the copper foil 52 + the thickness of the through-hole conductor 55. Therefore, in the state of FIG. 4C, the conductor thickness on the filled resin 56 is thinner than the conductor thickness on the insulating substrate 51 by the thickness of the copper foil 52 + the thickness of the through-hole conductor 55. At this time, the stress increases in the vicinity of the protruding portion of the filling resin 56, and the plating film 57 is likely to be peeled off. Since the conductor thickness on the filling resin 56 is thin, there is a risk of penetrating the conductor when laser processing the build-up layer formed on the conductor. Since the arithmetic mean roughness Ra of the interface between the insulating substrate 51 of the double-sided copper-clad laminate 53 and the copper foil 52 is large, the transmission loss of the insulating substrate 51 becomes large, which is disadvantageous as a high-frequency substrate.

In the method for manufacturing a printed wiring board according to the present invention, a first surface, an insulating substrate having a second surface opposite to the first surface, and a first surface laminated on the first surface of the insulating substrate. A double-sided copper-clad laminate formed of a copper foil and a second copper foil laminated on the two surfaces is prepared, and a through hole penetrating the double-sided copper-clad laminate is provided with the double-sided copper-clad laminate. Forming a plate, forming a tubular through-hole conductor on the insulating substrate exposed from the through hole, forming a first plating film on the first copper foil, and forming the second plating film. Forming a second plating film on the copper foil, filling the through-hole conductor with a filling resin, and filling the first plating film, the first copper foil, a part of the through-hole conductor, and the filling. By removing a part of the resin, a first plane formed of the insulating substrate, the through-hole conductor, and the filled resin is formed on the first surface side, and the second plating film and the second plating film are formed. By removing the copper foil, a part of the through-hole conductor, and a part of the filling resin, a second plane formed of the insulating substrate, the through-hole conductor, and the filling resin is formed on the second surface side. To form a third plating film on the insulating substrate exposed from the first surface, the through-hole conductor, and the filling resin, and the insulating substrate exposed from the second surface and the through-hole conductor. A print including forming a fourth conductor circuit on the filling resin, forming a first conductor circuit from the third plating film, and forming a second conductor circuit from the fourth plating film. In the method of manufacturing a wiring plate, the through-hole conductor exposed from the first surface has a convex shape and has a shape of entering the through hole from the first surface, and the through-hole conductor exposed from the second surface has a convex shape. The shape is such that it enters the through hole from the second surface.

The printed wiring board according to the present invention has an insulating substrate having a first surface, a second surface opposite to the first surface, a through hole formed so as to penetrate the insulating substrate, and exposed from the through hole. A tubular through-hole conductor formed on the insulating substrate, a filling resin filled in the through-hole conductor, a first conductor circuit formed on the first surface of the insulating substrate, and the above. A printed wiring board including a second conductor circuit formed on the second surface of an insulating substrate, wherein the conductor thickness on the insulating substrate and the conductor thickness on the filling resin are the same, and the insulation is provided. The surface of the substrate and the surface of the filling resin are flush with each other, and only the first conductor circuit is formed on the first surface of the insulating substrate, and the surface of the insulating substrate is on the second surface. In, only the second conductor circuit is formed, and the first conductor circuit and the second conductor circuit are in contact with the through-hole conductor at a position deeper than the surface of the insulating substrate, and the through-hole conductor is formed. Both ends of the are convex.

(A) to (e) are diagrams for explaining each step in one embodiment of the method for manufacturing a printed wiring board according to the present invention, respectively. (A) to (d) are diagrams for explaining the subtractive construction method for forming the first conductor circuit and the second conductor circuit, respectively. (A) to (c) are diagrams for explaining the semi-additive construction method for forming the first conductor circuit and the second conductor circuit, respectively. (A) to (d) are diagrams for explaining each step in one embodiment of the conventional method for manufacturing a printed wiring board, respectively.

An embodiment of a method for manufacturing a printed wiring board according to the present invention will be described with reference to the drawings. In the examples shown in FIGS. 1 (a) to 1 (e), the dimensions of each member, particularly the dimensions in the height direction, are the actual dimensions so that the features of the present invention can be better understood. They are listed with different dimensions. Hereinafter, an embodiment of the method for manufacturing a printed wiring board according to the present invention will be described with reference to FIGS. 1 (a) to 1 (e).

First, as shown in FIG. 1A, the insulating substrate 1 is composed of a first copper foil 2-1 and a second copper foil 2-2 formed on both surfaces thereof by using the same method as before. A double-sided copper-clad laminate 3 is prepared, a through hole 4 is formed in the double-sided copper-clad laminate 3, and a first plating film 5-1 and a second copper foil 2-2 are formed on the first copper foil 2-1. A second plating film 5-2 and a tubular through-hole conductor 5-3 are formed on the insulating substrate 1 exposed from the through hole 4.

Here, as the double-sided copper-clad laminate 3, a commercially available double-sided copper-clad laminate (CCL) can be used. The through hole 4 can be formed by subjecting the double-sided copper-clad laminate 3 to a conventionally known method, for example, drilling or laser (CO ₂ , UV-YAG, excimer, etc.) processing. Further, after the formation of the through hole 4 and before the formation of the through hole conductor 5-3, the residue generated by the formation of the through hole on the surface of the insulating substrate 1 and the side surface of the through hole 4 is, for example, permanganate + sodium hydroxide. It is preferable to remove it by a desmear treatment using the above or a desmear treatment using plasma using CF ₄ . Further, the first plating film 5-1 and the second plating film 5-2 and the through-hole conductor 5-3 are formed by electroless copper plating and subsequent electrolytic copper plating.

Next, as shown in FIG. 1 (b), the filling resin 6 is filled in the through-hole conductor 5-3. Here, as the filling resin 6, for example, a thermosetting epoxy resin composition can be used, as is conventionally known. Further, as conventionally known, a printing method, a vacuum printing method, or the like can be used for filling the filling resin 6.

Next, as shown in FIG. 1 (c), the first plating film 5-1 and the first copper foil 2-1 and the first copper foil 2-1 are obtained by polishing and etching both surfaces of the double-sided copper-clad laminate 3. 2 The plating film 5-2, the second copper foil 2-2, a part of the through-hole conductor 5-3, and a part of the filling resin 6 are removed. By polishing and subsequent etching, the surface of the insulating substrate 1 and the surface of the filling resin 6 become flush with each other. At the same time, both ends of the through-hole conductor 5-3 on the side wall of the through hole 4 are convex and have a shape of entering the through hole 4 from the surface where the insulating substrate 1 and the filling resin 6 are flush with each other.

Here, as a method for polishing both surfaces of the double-sided copper-clad laminate 3, as conventionally known methods, methods such as buffing, belt polishing, and surface polishing can be used, and the polishing method depends on the product specifications. Use properly. Further, as conventionally known, any etching process using an etching solution can be used for etching both surfaces of the insulating substrate 1 and both ends of the through-hole conductor 5-3 after polishing. At this time, after etching, the Ra on the surface of the insulating substrate 1 is preferably 0.1 μm or more and 0.5 μm or less.

Next, as shown in FIG. 1 (d), both surfaces of the insulating substrate 1 and the surface of the filling resin 6 are flush with each other, and through-hole conductors 5-3 having convex ends at both ends are formed. The plating film 7-1 and the fourth plating film 7-2 of No. 3 are formed. The third plating film 7-1 and the fourth plating film 7-1 can be formed by electroless copper plating and subsequent electrolytic copper plating in the same manner as in the formation of the through-hole conductor 5-3. At this time, the thickness of the conductor (third plating film 7-1 and the fourth plating film 7-2) on the insulating substrate 1 and the conductor (third plating film 7-1 and the fourth plating) on the filling resin 6 are the same. The thickness of the film 7-2) is preferably 20 μm or more and 40 μm or less.

Finally, as shown in FIG. 1 (e), the third plating film 7-1 and the fourth plating film 7-2 are processed, and the first conductor circuit 8-1 and the second conductor are formed on the surface of the insulating substrate 1. The circuit 8-2 is formed. In order to form the first conductor circuit 8-1 and the second conductor circuit 8-2 from the third plating film 7-1 and the fourth plating film 7-2, a conventionally known subtractive method or semi-additive method is used. Can be used. At this time, the contact position between both ends of the through-hole conductor 5-3 and the first conductor circuit 8-1 and the second conductor circuit 8-2 is preferably a position deeper than the surface of the insulating substrate 1 by 5 μm or more.

Hereinafter, as a processing method used when forming the first conductor circuit 8-1 and the second conductor circuit 8-2 from the third plating film 7-1 and the fourth plating film 7-2, the subtractive method and the semi-additive method are used. Will be described with reference to FIGS. 2 (a) to 2 (d) and FIGS. 3 (a) to 3 (d), respectively. In the examples shown in FIGS. 2 (a) to 2 (d) and FIGS. 3 (a) to 3 (c), the same members as those shown in FIGS. 1 (a) to 1 (e) are designated by the same reference numerals. The explanation is omitted.

2 (a) to 2 (d) are diagrams showing the steps of one embodiment for forming the first conductor circuit 8-1 and the second conductor circuit 8-2 according to the subtractive method, respectively. First, with respect to the double-sided copper-clad laminate 3 (corresponding to FIG. 1 (d)) in which the third plating film 7-1 and the fourth plating film 7-2 shown in FIG. 2 (a) are formed, FIG. 2 (corresponding to FIG. 1 (d)) As shown in b), the resist 9 is formed at a position where the first conductor circuit 8-1 and the second conductor circuit 8-2 should be formed. After that, etching was performed on the double-sided copper-clad laminate 3 on which the resist 9 was formed, and as shown in FIG. 2 (c), the third plating film 7-1 and the fourth plating film 7-2 other than the resist 9 were removed. Then, the insulating substrate 1 is exposed. Finally, the resist 9 is removed to form the first conductor circuit 8-1 and the second conductor circuit 8-2, as shown in FIG. 2D. A known method can be used for forming the resist 9, etching, and removing the resist 9.

3 (a) to 3 (c) are diagrams showing the steps of one embodiment for forming the first conductor circuit 8-1 and the second conductor circuit 8-2 according to the semi-additive method, respectively. First, as shown in FIG. 3A, a resist is formed on the surface of the insulating substrate 1 in the state shown in FIG. 1C at a position where the first conductor circuit 8-1 and the second conductor circuit 8-2 are not formed. 9 is formed. Next, as shown in FIG. 3B, the third plating film 7-1 and the fourth plating film 7-2 are formed on the insulating substrate 1 in which the resist 9 does not exist. Finally, the resist 9 is removed to form the first conductor circuit 8-1 and the second conductor circuit 8-2, as shown in FIG. 3 (c). Also in this example, known methods can be used for forming the resist 9, etching, and removing the resist 9. The semi-additive method is more suitable for forming a narrow-pitch conductor pattern than the subtractive method.

Next, an embodiment of the printed wiring board manufactured according to the manufacturing method according to the present invention will be described with reference to FIG. 1 (e).

In the embodiment shown in FIG. 1 (e), the thickness of the first conductor circuit 8-1 and the second conductor circuit 8-2 on the insulating substrate 1 and the first conductor circuit 8-1 and the second conductor on the filling resin 6 The thickness of the circuit 8-2 is the same, and the conductor thickness is preferably 20 μm or more and 40 μm or less. The surface of the insulating substrate 1 and the surface of the filling resin 6 are flush with each other. The arithmetic mean roughness Ra of the surface of the insulating substrate 1 is 0.1 μm or more and 0.5 μm or less. Ra on the surface of the insulating substrate 1 and Ra on the surface of the filling resin 6 are substantially the same. The first plating film 5-1 on the first copper foil 2-1 and the first copper foil 2-1 does not exist on the first surface of the insulating substrate 1, and only the first conductor circuit 8-1 is formed. Has been done. The second plating film 5-2 on the second copper foil 2-2 and the second copper foil 2-2 does not exist on the second surface of the insulating substrate 1, and only the second conductor circuit 8-2 is formed. Has been done. The first conductor circuit 8-1 and the second conductor circuit 8-2 are in contact with the through-hole conductor 5-3 at a position deeper than the surface of the insulating substrate 1, and both ends of the through-hole conductor 5-3 are convex. Is. Preferably, the contact position between the through-hole conductor 5-3 exposed from the first surface of the insulating substrate 1 and the first conductor circuit 8-1 and the through-hole conductor 5-3 exposed from the second surface of the insulating substrate 1 The contact position between the and the second conductor circuit 8-2 is 5 μm or more deeper than the first surface and the second surface of the insulating substrate 1, respectively.

According to the printed wiring board of the present invention shown in FIG. 1 (e), the thickness of the first conductor circuit 8-1 and the second conductor circuit 8-2 on the insulating substrate 1 and the thickness of the first conductor circuit 8 on the filling resin 6 Since the thickness of -1 and the second conductor circuit 8-2 are the same, the filling resin 6 does not protrude from the insulating substrate 1 and is applied to the first conductor circuit 8-1 and the second conductor circuit 8-2. The stress can be made uniform. Further, since the thickness of the first conductor circuit 8-1 and the second conductor circuit 8-2 can be preferably increased to 20 μm or more and 40 μm or less, even if the upper layer is laser-machined, the first conductor circuit 8-1 and the second conductor circuit 8-1 and the second conductor are formed. The risk of penetrating the circuit 8-2 can be reduced.

Further, since the surfaces of the insulating substrate 1 and the filling resin 6 are polished and etched, the surface can be preferably as small as 0.1 μm or more and 0.5 μm or less, the transmission loss can be reduced, and the surface can be used for high frequencies. It is advantageous as a printed wiring board. Further, since both ends of the through-hole conductor 5-3 have a convex shape and have a structure that penetrates into the through-hole to a position preferably 5 μm or more deeper than the surface, the first conductor circuit 8-1 and the second conductor circuit 8-2 is less likely to peel off from the insulating substrate 1 and the filling resin 6, and the first conductor circuit 8-1 and the second conductor circuit 8-2 can be firmly formed.

1 Insulated substrate 2-1 1st copper foil 2-2 2nd copper foil 3 Double-sided copper laminated board 4 Through hole 5-1 1st plating film 5-2 2nd plating film 5-3 Through-hole conductor 6 Filling resin 7 -1 3rd plating film 7-2 4th plating film 8-1 1st conductor circuit 8-2 2nd conductor circuit 9 Resist

Claims (9)

An insulating substrate having a first surface, a second surface opposite to the first surface, and a first copper foil laminated on the first surface of the insulating substrate are laminated on the two surfaces. Preparing a double-sided copper-clad laminate made of the second copper foil,
By forming a through hole penetrating the double-sided copper-clad laminate in the double-sided copper-clad laminate,
Forming a cylindrical through-hole conductor on the insulating substrate exposed from the through hole, and
Forming the first plating film on the first copper foil and
Forming a second plating film on the second copper foil and
Filling the through-hole conductor with a filling resin and
By removing the first plating film, the first copper foil, a part of the through-hole conductor, and a part of the filling resin, the insulating substrate, the through-hole conductor, and the filling resin are on the first surface side. To form the first plane formed by
By removing the second plating film, the second copper foil, a part of the through-hole conductor, and a part of the filling resin, the insulating substrate, the through-hole conductor, and the filling resin are on the second surface side. To form the second plane formed by
Forming a third plating film on the insulating substrate exposed from the first surface, the through-hole conductor, and the filling resin, and
Forming a fourth plating film on the insulating substrate exposed from the second surface, the through-hole conductor, and the filling resin.
Forming the first conductor circuit from the third plating film and
It is a method of manufacturing a printed wiring board including forming a second conductor circuit from the fourth plating film.
The through-hole conductor exposed from the first surface has a convex shape and has a shape that enters the through hole from the first surface.
The through-hole conductor exposed from the second surface has a convex shape and has a shape that enters the through hole from the second surface. In the method for manufacturing a printed wiring board according to claim 1, the formation of the through-hole conductor, the formation of the first plating film, and the formation of the second plating film are performed at the same time, and the third plating film is formed. The formation of the plating film and the formation of the fourth plating film are performed at the same time. The method for manufacturing a printed wiring board according to claim 1 or 2, wherein the first plating film, the first copper foil, a part of the through-hole conductor, and a part of the filling resin are removed, and the second. Removal of the plating film, the second copper foil, a part of the through-hole conductor, and a part of the filling resin is performed by polishing and etching. In the method for manufacturing a printed wiring board according to claim 1 or 2, forming the first conductor circuit from the third plating film and forming the second conductor circuit from the fourth plating film is a subtra. It is carried out by the active method or the semi-additive method. An insulating substrate having a first surface and a second surface opposite to the first surface,
A through hole formed so as to penetrate the insulating substrate,
A tubular through-hole conductor formed on the insulating substrate exposed from the through hole, and
The filling resin filled in the through-hole conductor and
A first conductor circuit formed on the first surface of the insulating substrate and
A printed wiring board comprising a second conductor circuit formed on the second surface of the insulating substrate.
The conductor thickness on the insulating substrate and the conductor thickness on the filling resin are the same,
The surface of the insulating substrate and the surface of the filling resin are flush with each other.
Only the first conductor circuit is formed on the first surface of the insulating substrate.
Only the second conductor circuit is formed on the second surface of the insulating substrate.
The first conductor circuit and the second conductor circuit are in contact with the through-hole conductor at a position deeper than the surface of the insulating substrate.
Both ends of the through-hole conductor are convex. In the printed wiring board of claim 5, the conductor thickness on the insulating substrate and the conductor thickness on the filling resin, which are the same, are 20 μm or more and 40 μm or less. In the printed wiring of claim 5, Ra on the surface of the insulating substrate is 0.1 μm or more and 0.5 μm or less. The printed wiring board according to claim 5, wherein the through-hole conductor exposed from the first surface and the first conductor circuit are in contact with each other, and the through-hole conductor exposed from the second surface and the second conductor circuit. The contact position with the insulation substrate is 5 μm or more deeper than the surface of the insulating substrate. In the printed wiring board of claim 5, Ra on the surface of the insulating substrate and Ra on the surface of the filling resin are substantially the same.

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