JPH07336051A - Printed circuit board and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a printed circuit board having excellent dimensional stability and low-cost by disposing a core layer having a resin-impregnated woven fabric base material in an inner layer, and forming an insulating layer directly under a conductor circuit of the base material. CONSTITUTION:A copper-plated laminated plate is obtained by disposing a layer of resin-impregnated woven fabric 10 to become the core layer of the part of an inner layer, disposing a copper foil to become a conductor circuit 31 on the outermost layer, disposing at least resin-impregnated nonwoven fabric 20 between the both, laminating it and integrating it. Then, a through hole 41 or a non-penetrated hole 46 are formed by selectively etching the foil. That is, when the hole 41 or 46 is formed by drilling, the copper-plated laminated plate in which the insulating layer directly under the foil of the cutting starting side is formed of the fabric 20 is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board having through holes and a method of manufacturing the same, and particularly to a printed wiring board having excellent dimensional stability and low cost, and a manufacturing cost being low and drilling hole precision being excellent. And a method for manufacturing a printed wiring board.

[0002]

2. Description of the Related Art At present, there are the following materials for forming a printed wiring board. (1) A printed wiring board using an insulating layer obtained by impregnating a thermosetting resin in a nonwoven fabric made of paper, aramid fiber or glass fiber. (2) A printed wiring board using an insulating layer obtained by impregnating a woven cloth made of glass fibers with a thermosetting resin. (3) A printed wiring board using a ceramic material such as alumina or aluminum nitride as an insulating layer. However, in recent years, (1) or (2) except for special cases in terms of material cost and through hole processability.
Printed wiring boards are widely used.

In the printed wiring board of (1), the insulating layer is made of paper or non-woven fabric impregnated with resin (hereinafter referred to as resin-impregnated non-woven fabric), so that the printed wiring board is heat-treated during soldering. The dimensional change of becomes large. Therefore, it cannot be used for applications such as mounting fine electronic components at high density, and is used for producing "rough substrates" at low cost. Further, in the printed wiring board of (2), unlike the former, the material forming the insulating layer is a material obtained by impregnating a thermosetting resin into a woven cloth such as glass fiber (hereinafter referred to as a resin-impregnated woven cloth). It has excellent dimensional stability against heat treatment. Therefore, a through hole having a small diameter is formed, which is optimal for applications such as a multilayer printed wiring board which requires a heating / pressing / laminating / pressing step.

[0004]

However, the printed wiring board of (2) has a higher material cost than the printed wiring board of (1) and has the following problems. A printed wiring board using a resin-impregnated woven fabric as an insulating layer is a copper clad laminate that is a starting material by placing a copper foil on the outer surface of an uncured or semi-cured resin-impregnated woven fabric and heating and pressing it. The folds of the woven fabric such as glass fibers located immediately below are transferred to the surface of the copper foil of the copper clad laminate by the heating and pressing process. The transferred folds appear as irregularities on the surface of the copper foil, and cause the occurrence of drill shake that deteriorates the hole position accuracy during the drill cutting process at some time. Therefore,
Conventionally, a flat plate having a good "drill bite" such as a bake plate is arranged on the outer layer of the copper clad laminate which is the object to be cut to make a hole. This bake board is a "useless material" that does not constitute the final printed wiring board.
It is obvious that the thickness of the machined plate is large, the wear of the drill is accelerated, and the number of lapped holes is reduced. Therefore, it is difficult to reduce the manufacturing cost.

The present invention has been made in view of the above problems, and provides a printed wiring board having excellent dimensional stability and low cost, as well as low manufacturing cost and high accuracy of drilling holes. An object of the present invention is to provide an excellent printed wiring board manufacturing method.

[0006]

Means for Solving the Problems The means adopted by the present invention to solve the above-mentioned problems are as follows. First, a layer of a printed wiring board having through holes (41, 46) connected to a conductor circuit (31) on the surface layer. The structure is such that a core layer containing a resin-impregnated woven fabric substrate (10) is arranged as an inner layer, and an insulating layer consisting of a resin-impregnated nonwoven fabric substrate (20) is provided immediately below the conductor circuit (31). .

Further, in the manufacturing method of the present invention, a layer of the resin-impregnated woven fabric (10) serving as the core layer is arranged in a part of the inner layer, and the copper foil (30) serving as the conductor circuit (31) is provided in the outermost layer. And a resin-impregnated non-woven fabric (21) is placed between them to laminate and integrate to obtain a copper-clad laminate. Next, a through hole (40) or a non-through hole (45) is formed by drilling from the copper foil (30) side,
After that, by selectively etching the copper foil (30), the conductor circuit (3
1) is formed. That is, when the through hole (40) or the non-through hole (45) is formed by drilling, the insulating layer immediately below the copper foil (30) on the cutting start side is formed by the resin-impregnated nonwoven fabric (21). A laminated laminate is used.

[0008]

[Advantages] The following actions are achieved by adopting the above means. First, as a copper-clad laminate that constitutes a printed wiring board, a resin-impregnated woven fabric base material (10) having excellent dimensional stability is arranged in the inner layer, so that it is equivalent to a conventional printed wiring board. It has dimensional stability. Further, since the resin-impregnated non-woven fabric base material (20) with low material cost is used for the insulating layer located at the outermost layer of this copper-clad laminate, the printed wiring board as a whole becomes a low-cost printed wiring board. .

In the manufacturing method, since a resin-impregnated non-woven fabric (21) having no large undulations such as a resin-impregnated woven fabric is used in the insulating layer immediately below the copper foil (30) on the drilled surface side, Almost no unevenness of the insulating layer directly below is transferred to the surface of the copper foil (30), resulting in a very flat surface state. Therefore, the drill does not escape during the drill cutting process, so-called "bite of the drill" is improved, and the through hole (40) or the non-through hole (45) with high processing accuracy without drill blur can be formed. Further, since the "bite of the drill" is good, it is not necessary to use a backing plate such as a baking plate as in the conventional case. Therefore, reduction of material cost such as bake plate,
By reducing the thickness of the plate to be cut, the number of lapped holes can be increased and the processing cost can be greatly reduced.

[0010]

EXAMPLES Next, as specific examples of the present invention, the manufacturing steps thereof will be described step by step. (1) 1.1 mm thick epoxy resin impregnated glass woven base material
Double-sided copper clad laminate consisting of (10) (Hitachi Kasei, standard: FR
-4, trade name: MCL-E-67) was selectively etched copper foil (35 μm) on both main surfaces to form a conductor circuit (32), thereby forming a core substrate (FIG. 2). (2) After conducting the roughening treatment on the conductor circuit (32) on the surface of the core substrate, a semi-cured resin-impregnated glass non-woven fabric (21) having a thickness of 0.1 mm is formed on both sides of the conductor circuit (32) with a thickness of 18 μm. One side roughened copper foil
(30) (Mitsui Kinzoku) Combine and stack (Fig. 3), set in a multi-stage vacuum hot press, preheat temperature 120 ° C, heating rate 3 ° C / min, 175 ° C, 30 kg / cm ² , hold for 2 hours By heating and pressurizing under the conditions of (1) and integrating, a laminated plate having a thickness of 1.5 mm was obtained (FIG. 4).

(3) Two sheets of the above laminated and laminated laminated plate are superposed, and the cutting surface side thereof is directly manufactured by Hitachi NSK without using a backing plate such as a conventional baking plate. / C hole drilling machine, 0.3mmφ through hole (40)
And a non-through hole (45) was formed (FIG. 5). (4) After washing the laminated plate having the through holes (40) and the non-through holes (45) formed therein, it is immersed in a catalyst solution for electroless plating (manufactured by Shipley, trade name: Cataposit 44) for 5 minutes, and then Electroless copper plating solution (made by Shipley, trade name: 328
L) for 20 minutes to deposit a plating film having a thickness of 0.3 μm, and then in an electrolytic copper plating solution at 23 ° C., 2.0 A /
It was immersed for 60 minutes at a current density of dm ² to deposit a plating film having a thickness of 25 μm for through hole plating.

(5) Next, the conductor circuit (31) is formed by selectively etching the copper foils (30) on both main surfaces, and a predetermined portion is solder resist (trade name: HR- manufactured by Hitachi Chemical Co., Ltd.). 6060) A printed wiring board having a desired four-layer structure was formed by coating with a coating (FIG. 5).

Further, as Comparative Example 1, except that the semi-cured resin-impregnated glass nonwoven fabric (21) in the step (2) is a semi-cured resin-impregnated glass woven fabric (manufactured by Hitachi Chemical, trade name: GEA-67N). A printed wiring board having a four-layer structure was formed in the same manner as in the above example. Furthermore, as Comparative Example 2, the double-sided copper-clad laminate in the step (1) was replaced by a double-sided copper-clad laminate composed of a 0.8 mm-thick epoxy resin-impregnated glass nonwoven fabric substrate (Matsushita Electric Works, trade name: CEM- A printed wiring board having a four-layer structure was formed in the same manner as in the above-described example except that 3) was adopted.

[0014]

Table 1 shows the measurement results of the positional accuracy of the through holes and the dimensional changes before and after the heat treatment of the hot press in the step (2) of the various printed wiring boards thus formed. As is clear from this table, the printed wiring board of the present invention can realize the through hole position accuracy far superior to that of Comparative Example 1, and
It has dimensional stability comparable to that of Comparative Example 1. Further, it is possible to realize the through hole position accuracy comparable to that of the comparative example 2 and to have the dimensional stability significantly superior to that of the comparative example 2.

Further, the embodiment of the present invention can be modified and implemented as follows, and the same effect can be exhibited by these. (1) Instead of the resin-impregnated woven fabric base material that is the core base material, a multilayer printed wiring board including a resin-impregnated base material in its inner layer is used. (2) Instead of using a resin-impregnated non-woven fabric (prepreg) as the outermost insulating layer, use a resin-impregnated non-woven fabric substrate, that is, a single-sided or double-sided copper-clad laminate (may have through holes) Good. In this case, a new adhesive layer is required for adhesion to the resin-impregnated woven fabric base material that becomes the core base material. (3) Instead of using a resin-impregnated non-woven fabric (prepreg) as an insulating layer located on both outermost layers, a resin-impregnated non-woven fabric substrate, that is, a single-sided or double-sided copper-clad laminate (through holes may be formed) is used. May be. In this case, the resin-impregnated woven fabric substrate is not used as the core substrate, but both resin-impregnated nonwoven fabric substrates are bonded and integrated using a prepreg made of the resin-impregnated woven fabric. (4) In the above (3), a single-sided or double-sided copper-clad laminate (through hole) made of a resin-impregnated woven fabric substrate may be formed between the resin-impregnated non-woven fabric substrates located at both outermost layers. ), Or alternatively, a multilayer printed wiring board including a resin-impregnated base material is placed in the inner layer, and laminated and integrated by another adhesive layer.

[0017]

As described above, in the printed wiring board of the present invention, since the resin-impregnated woven fabric excellent in dimensional stability and the resin-impregnated non-woven fabric which is low in material cost are used, the conventional printed wiring board can be used. It has the same dimensional stability and a low cost as a whole printed wiring board.
Further, in the method for manufacturing a printed wiring board of the present invention,
It is possible to form a through hole or a non-through hole with a high processing accuracy, in which the drill does not escape during the drilling process, so-called "bite of the drill" is improved, and there is no drill blurring. Furthermore,
It does not require a backing plate such as a bake plate, but can significantly reduce the processing cost by reducing the thickness of the plate to be cut and by making multiple holes.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a printed wiring board of the present invention.

FIG. 2 is a partial cross-sectional view showing a first manufacturing step of the printed wiring board of the present invention.

FIG. 3 is a partial cross-sectional view showing a second manufacturing step of the printed wiring board of the present invention.

FIG. 4 is a partial cross-sectional view showing a second manufacturing step of the printed wiring board of the present invention.

FIG. 5 is a partial cross sectional view showing a third manufacturing step of the printed wiring board of the present invention.

FIG. 6 is a partial cross sectional view showing a fifth manufacturing step of the printed wiring board of the present invention.

[Explanation of symbols]

10 == Resin-impregnated woven fabric substrate 20 == Resin-impregnated non-woven fabric substrate
21 == Resin impregnated non-woven fabric 30 == Copper foil 31 == Conductor circuit 32 == Inner layer conductor circuit 40
== Through hole 41 == Through hole 45 == Non-through hole 46 == Non-through hole

Claims (2)

[Claims] 1. A printed wiring board having a through hole connected to a conductor circuit of a surface layer, wherein a core layer containing a resin-impregnated woven fabric substrate is provided as an inner layer, and an insulating layer immediately below the conductor circuit is resin-impregnated. A printed wiring board comprising a non-woven fabric substrate. 2. A method of manufacturing a printed wiring board having a through hole for connecting to a conductor circuit on a surface layer, wherein a core base material including a resin-impregnated woven fabric which forms a core layer and a copper foil which forms the conductor circuit are resin-impregnated non-woven fabric. A method for manufacturing a printed wiring board, characterized in that a through hole or a non-through hole is formed by drilling from the copper foil side, and then a conductor circuit is formed.