JP2002076613A - Method for manufacturing printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a printed circuit board capable of realizing an increase in a density of a wiring pattern at a low cost without lowering connecting reliability. SOLUTION: The method for manufacturing the printed circuit board comprises the steps of forming a through hole 3 at a double-sided copper-clad laminate 4 in which copper foils 2 are laminated on both surfaces, executing copper-plating or the like on an inner wall of the hole 3 and the foils 2 of both the surfaces of the board so as to connect the foils 2 of the surfaces of the laminate 4 via the hole 3, and embedding and printing paste having etching resistance in the hole 3. The method further comprises the steps of half etching the laminate 4 in which a hole filling resin 7 is filled in the hole 3, removing a part of a copper-plating layer 5 in a thickness direction, polishing the resin 7 projected from the surface of the board together with a conductor layer 6 retained on the board to flatten the surface of the board, and forming an electrode pad 8 on the flattened resin 7. Thus, a density of the wiring pattern can be enhanced without lowering the connecting reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a printed wiring board for realizing high-density mounting of electronic components.

[0002]

2. Description of the Related Art In recent years, printed wiring boards for mounting integrated circuit components such as ICs and LSIs have been further densified by multi-layering and fine patterning. This contributes to the reduction in size and weight of the equipment. An example of a printed wiring board that has realized a higher density of wiring patterns is, for example, a build-up board.

In this build-up substrate, an insulating layer and a circuit layer are alternately formed on an inner substrate serving as a base. For example, a blind via hole is formed on an inner via hole provided in an inner layer. In addition, the density of the wiring pattern is increased by providing a pad for mounting components on the blind via hole.

A method of forming an inner via hole in an inner layer of a base substrate and forming a component mounting pad or a blind via hole on the formed inner via hole will be described.

First, a through-hole is formed in a double-sided copper-clad laminate, and copper plating is performed on the inner wall of the through-hole and the copper foil on both sides of the substrate so that the copper foils on both sides of the substrate are connected to each other through the through-hole. Is applied. Next, a filling resin is filled into the through hole provided with the copper plating, and after the resin is cured, the excess filling resin protruding from the opening surface of the through hole is removed by mechanical polishing to flatten the substrate surface. . Further, a method of subjecting so-called lid plating to the flattened via hole, based on this, a method for forming a component mounting pad and further forming a blind via hole on the pad are mainly employed.

[0006]

However, in such a conventional method for manufacturing a printed wiring board, copper plating is further performed twice on a copper foil previously laminated on the substrate surface. In addition, the thickness of the conductor is increased, which is a factor that hinders the fine pattern formation required in recent years.

[0007] Therefore, for example, it is conceivable to reduce the thickness of the copper foil laminated on the substrate, but in this case, the usable copper foil becomes expensive. Also, for example, when trying to reduce the plating thickness when connecting copper foil on both sides of the board,
Of course, the plating thickness formed on the inner wall of the through hole is also reduced,
If the thickness of the lid plating is reduced, the adhesion between the lid plating and the filling resin is impaired.

The present invention has been made to solve such a problem, and provides a method of manufacturing a printed wiring board capable of realizing a high-density wiring pattern at a low cost without lowering connection reliability. Things.

[0009]

According to a first aspect of the present invention, there is provided a method for manufacturing a printed wiring board, comprising the steps of: forming a hole in a substrate having conductor layers laminated on both sides; Forming a conductor layer further on the inner wall of the hole and the conductor layer so that the conductor layer laminated on each surface of the substrate is connected, and wherein the conductor layer is formed on the inner wall. Filling the hole portion of the substrate with a filling material,
Removing the conductor layer on the substrate in which the hole portion is filled with the filling material while leaving a predetermined thickness, and removing the conductor layer together with the conductor layer that remains the filling material protruding from above the substrate. A step of polishing to flatten the substrate surface; and a step of forming a circuit pattern on the flattened hole filling material.

According to a second aspect of the present invention, in the method for manufacturing a printed wiring board according to the first aspect, the conductor layer is removed by half etching. I do.

Further, a method of manufacturing a printed wiring board according to claim 3 of the present invention is characterized in that, in the method of manufacturing a printed wiring board according to claim 1 or 2, the filling material has etching resistance. I do.

In the above-described method of manufacturing a printed wiring board according to the present invention, for example, a through hole or a non-through hole reaching one conductor layer is formed on a substrate having conductor layers laminated on both sides, and each surface of the substrate is formed. In order to connect the conductive layers through the holes, the inner walls of the holes and the conductive layers on both sides of the substrate are subjected to copper plating or the like, and the holes are filled with an etching-resistant paste or the like. It is. Further, the method for manufacturing a printed wiring board of the present invention is characterized in that a half-etching or the like is performed on a substrate having a hole filled with a filling resin or the like to remove a part of the conductor layer in the thickness direction, and the substrate is removed by removing the conductor layer The filling resin or the like protruding from the surface is polished together with the conductor layer remaining on the substrate to flatten the substrate surface, and a circuit pattern is formed on the flattened filling resin or the like.

Therefore, according to the method for manufacturing a printed wiring board of the present invention, the plating thickness formed on the inner wall of the hole is reduced, and an expensive copper foil for reducing the conductor thickness is used. Thus, a circuit formed on a substrate can be formed into a fine pattern without causing a decrease in electrical connection reliability, and a high-density wiring pattern can be realized at low cost.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a view schematically showing an inner via hole portion of a printed wiring board according to an embodiment of the present invention.

As shown in FIG.
Has an electrode pad for component mounting on the inner via hole 16 in the inner layer of the base substrate.
Are laminated on both sides and a double-sided copper-clad laminate 4 as a base substrate having a through-hole 3 formed therein, and the inner wall of the through-hole 3 is connected to the copper foil 2 on each side of the laminate 4. A copper plating layer 5 formed by performing copper plating and a conductor layer formed by further performing copper plating on the copper foil 2 together with the formation of the copper plating layer 5 are removed while leaving a predetermined thickness. Conductor layer 6, a filling resin 7 filling the through hole 3 in which the copper plating layer 5 is formed on the inner wall, and pads (circuits) formed on the upper and lower surfaces of the filling resin 7 having a flattened surface. 8).

Next, a method for manufacturing the printed wiring board 1 configured as described above will be described with reference to FIG.

First, as shown in FIG. 2A, a double-sided copper-clad laminate 4 having copper foils 2 formed on both sides in advance is prepared, and this double-sided copper-clad laminate 4 is shown in FIG. 2B. Thus, the through hole 3 is formed. Next, as shown in FIG. 2C, through-hole panel plating is performed on the through-hole 3, and a copper plating layer 5 is formed on the inner wall of the through-hole 3 and on the copper foil 2. Further, as shown in FIG. 2D, after filling and curing a filling resin 7 in a hollow portion of the through hole 3 on which the through hole plating is performed, unnecessary resin adhering around the upper and lower end surfaces of the through hole 3 is removed. Removal and flattening of the surface of the substrate. Next, the copper plating layer 5 (including the copper foil 2) on the flattened substrate surface is removed by half etching to leave a predetermined thickness as shown in FIG.

Further, as shown in FIG. 2 (f), the filling resin 7 projecting from the surface of the double-sided copper-clad laminate 4 is polished together with the conductor layer 6 by half-etching, and the surface of the double-sided copper-clad laminate 4 is polished. Flatten. Next, as shown in FIG. 2 (g), lid plating 9 is formed on both sides of the laminated board 4, and the lid plating 9 is etched to form pads (circuit patterns) 8 as shown in FIG. 2 (h). Forming the pad 8 on the inner via hole 16 in the inner layer of the base substrate.
The printed wiring board 1 on which is laminated is manufactured. After that, by performing well-known manufacturing processes such as lamination press, blind via formation, circuit formation, and external processing, a desired printed wiring board can be completed.

As described above, in the method of manufacturing the printed wiring board 1 of the present embodiment, the through holes 3 are formed in the double-sided copper-clad laminate 4 having the copper foils 2 laminated on both sides, and Copper foil 2
The inner wall of the through-hole 3 and the copper foil 2 on both surfaces of the substrate are plated with copper or the like so as to be connected through the through-hole 3, and the inside of the through-hole 3 is filled with an etching-resistant paste. Is what you do. Further, the method of manufacturing the printed wiring board 1 of the present embodiment is a
A half-etching is performed on the laminated plate 4 filled with, and a part of the conductor layer is removed in the thickness direction, and the filling resin 7 protruding from the substrate surface by removing the conductor layer is polished together with the conductor layer remaining on the substrate. Thus, a circuit pattern is formed on the flattened filling resin 7 by flattening the substrate surface.

Therefore, according to the method of manufacturing the printed wiring board 1 of the present embodiment, the plating thickness formed on the inner wall of the through hole 3 is reduced, and expensive copper for reducing the plating thickness and the like is used. Fine patterning of the circuit formed on the substrate can be achieved without using foil, so high-density wiring patterns can be realized at low cost without reducing electrical connection reliability. Can be.

Although the present invention has been described in detail with reference to the embodiment, the present invention is not limited to the above embodiment and can be variously modified without departing from the gist thereof. For example, in the present embodiment, the pads 8 are formed on the inner via holes 16 in the inner layer of the double-sided copper-clad laminate 4 based on the through-holes 3. A non-through hole reaching the inner layer copper foil is formed, and the non-through hole is subjected to electrolytic plating, resin filling, half etching, flattening polishing, and lid plating to form a blind via hole, and to form a pad 8 and a circuit pattern. May be formed. After the non-through hole is formed, filling with a conductive paste, half etching, flattening polishing, and lid plating may be performed.

[0023]

Next, an embodiment of the present invention will be described with reference to FIGS. In this embodiment, one blind via hole is formed on the inner via hole 16 in the inner layer of the base substrate.
A method for manufacturing the four-layered build-up substrate 17 having 3 will be described.

First, as shown in FIG. 2A, a double-sided copper-clad laminate 4 made of glass epoxy having a substrate thickness of 0.6 mm and a copper foil 2 having a thickness of 12 μm was prepared. As shown in (1), a through hole 3 is formed in the double-sided copper-clad laminate 4 by a drill having a diameter of 0.25 mm. Next, as shown in FIG. 2C, the copper foils 2 on both sides of the double-sided copper-clad laminate 4 are connected through the through holes 3.
Is plated with a copper panel with a set thickness of 20 μm.
A copper plating layer 5 is formed on the inner wall and the copper foil 2. Further, as shown in FIG. 2D, the hollow portion of the through hole 3 on which the through-hole plating has been performed is filled with an epoxy filling resin 7 which is permanently buried by screen printing, and is cured by heating. Thereafter, unnecessary resin adhering to the periphery of the upper and lower end surfaces of the through hole 3 is removed by polishing using a ceramic roll and a buff, and the surface of the substrate is flattened.

Next, as shown in FIG. 2 (e), half of the conductive layer remaining on the double-sided copper-clad laminate 4 is spray-etched using cupric chloride as an etchant so that the thickness of the conductor layer becomes about 8 μm. Etching is performed to form the conductor layer 6. Further, as shown in FIG. 2 (f), using a ceramic roll and a buff, the filling resin 7 protruding from the surface of the double-sided copper-clad laminate 4 so that the remaining thickness of the conductor layer 6 becomes 5 μm. Polishing is performed together with the conductor layer 6 to flatten the surface of the double-sided copper-clad laminate 4. Next, as shown in FIG. 2 (g), a copper plating of a set thickness of 12 μm is applied to both surfaces of the laminate 4 to form a lid plating 9, and the lid plating 9 is etched to form a lid plating 9 as shown in FIG. The circuit pattern 8 is formed as shown in FIG. Thereafter, as shown in FIG.
12 μm thick copper foil (copper plated layer) 1
Using a resin sheet 12 with a copper foil on which 1 is laminated, lamination molding is performed by hot pressing, laser processing, formation of a blind via hole 13 by copper plating, formation of a circuit pattern 14, and formation of a solder resist 15 Then, a four-layer build-up substrate 17 is completed.

As a result, the thickness, characteristics, etc. of the conductor layers of the printed wiring board manufactured according to the above embodiment and the printed wiring board manufactured by the conventional method without using half etching are as shown in the following table. It became.

[0027]

[Table 1]

[Table 2] As is clear from these results, according to the method for manufacturing a printed wiring board of the present embodiment, it is possible to form a fine pattern of a circuit formed on a substrate without reducing electrical connection reliability. It is possible.

[0028]

As described above, according to the present invention, a hole is formed in a substrate having conductor layers laminated on both sides, and the hole is formed so that the conductor layers on each side of the substrate are connected through the hole. Copper plating or the like is applied to the inner wall of the unit and the conductor layers on both surfaces of the substrate, and a filling resin or the like is embedded in these holes. Furthermore, the present invention provides a substrate in which a hole filling resin or the like is embedded by half-etching or the like to remove a part of the conductor layer in the thickness direction, and also removes the conductor layer from the substrate surface by removing the conductor layer. Is polished together with the conductor layer remaining on the substrate to flatten the substrate surface, and a circuit pattern is formed on the flattened resin or the like.

Therefore, according to the present invention, the thickness of the plating formed on the inner wall of the hole is reduced, and the expensive copper foil for reducing the thickness of the copper foil is not used on the substrate. Since a circuit to be formed can be formed into a fine pattern, it is possible to realize a high-density wiring pattern at low cost without deteriorating electrical connection reliability.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a printed wiring board according to an embodiment of the present invention.

FIG. 2 is a view for explaining a method of manufacturing the printed wiring board of FIG. 1;

FIG. 3 is a view schematically showing a build-up board manufactured by applying the method for manufacturing a printed wiring board of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Printed wiring board 2 ... Copper foil 3 ... Through-hole 4 ... Double-sided copper-clad laminate 5 ... Copper plating layer 6 ... Conductive layer formed by half etching 7 ... Filling resin 8 ... Pad (circuit pattern) 9 ... Lid plating DESCRIPTION OF SYMBOLS 10 ... Insulating layer 11 ... Copper foil and copper plating layer 12 ... Resin sheet with copper foil 13 ... Blind via hole 14 ... Circuit pattern 15 ... Solder resist 16 ... Inner via hole 17 ... Build-up board

Claims (3)

[Claims] A step of forming a hole in a substrate having a conductor layer laminated on both sides thereof; and an inner wall of the hole and the conductor layer such that the conductor layers laminated on each surface of the substrate are connected. Further laminating a conductor layer on the substrate; filling the hole portion of the substrate with the conductor layer laminated on the inner wall with a filling material; and filling the hole portion with the filling material. Removing the conductor layer with a predetermined thickness, polishing the hole filling material protruding from above the substrate together with the remaining conductor layer by removing the conductor layer, and flattening the substrate surface; Forming a circuit pattern on the formed hole filling material. 2. The method for manufacturing a printed wiring board according to claim 1, wherein the removal of the conductive layer is performed by half etching. 3. The method for manufacturing a printed wiring board according to claim 1, wherein the filling material has etching resistance.