JP2000315863A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a multilayer printed wiring board which can surely realize interlayer connection of wiring layers, when a multilayer printed wiring board of IVH structure is formed, and is superior in alignment accuracy. SOLUTION: A film 3 is stuck on a resin substrate 1 of a resin substrate 11 with a copper foil, and an aperture part is formed in the film 3 and the resin substrate 1 by laser working, using the copper foil 2 as a stopper. The sidewall surface of an aperture part 4 and the copper foil surface are subjected to cleaning treatment, the aperture part 4 is filled with a conductive paste, the film 3 is peeled and removed, and an outer layer substrate 10 is formed in which a semicured conductive paste conductor 5, having protruding parts on the resin substrate 11 with a copper foil, is formed. An outer layer substrate 20 is formed by a similar process. An inner layer substrate 30, in which a wiring layer 22 and a wiring layer 23 are formed, is made a core. The outer layer substrate 10 and the outer layer substrate 20 are laminated on both sides of the core. A multilayer printed wiring board is formed by heating and pressing with pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board used as a high-density mounting board for various electronic devices, and more particularly to a method for manufacturing a multilayer printed wiring board capable of reliably obtaining electrical connection between wiring layers.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and lighter, mounting boards constituting them have been required to have higher density and higher reliability. 2. Description of the Related Art A multilayer wiring board having an inner via hole (hereinafter, referred to as IVH) structure has been used as one method of reducing the size and increasing the density of a multilayer wiring board. In this multilayer wiring board, since the IVH can be formed between any layers, the component arrangement can be freely set, and the wiring length can be shortened as compared with the conventional through-hole structure. Widely used as a board.

FIGS. 2 (a) to 2 (h) show an example of a conventional process of manufacturing a multilayer wiring board having an IVH structure. Hereinafter, a method for manufacturing a multilayer wiring board having an IVH structure will be described with reference to the drawings. First, a prepreg resin substrate 61 in which an aramid nonwoven fabric is impregnated with an epoxy resin is perforated by laser processing such as carbon dioxide gas laser to form an opening 62 (see FIGS. 2A and 2B).

[0004] Next, a conductive paste is filled in the opening 62 and preliminarily dried to obtain a semi-cured conductive paste conductor 63.
To form Copper foil 64 on both sides of prepreg resin substrate 61
And 65 are heated and pressed to produce a laminate (see FIGS. 2C and 2D). In this heating and pressing step, the epoxy resin of the prepreg resin substrate 61 and the resin of the conductive paste conductor 63 are cured, and the copper foil 64 and the copper foil 65 are electrically connected by the conductive paste conductor 63. . Next, the copper foil 64 and the copper foil 65 are patterned to form the wiring layer 64a and the double-sided wiring board 60 on which the wiring layer 65a is formed.
(See FIG. 2E).

Next, a prepreg 71 and a prepreg 72 on which a conductive paste conductor is formed with the double-sided wiring board 60 as a core, a copper foil 81 and a copper foil 82 are laminated on both surfaces of the double-sided wiring board 60 (FIG. f)).

Next, a multi-layer board 90 is produced by heating and pressing at a temperature of 180 to 200 ° C. (see FIG. 2 (g)). In this heating / pressing step, the epoxy resin of the prepreg 71 and the prepreg 72 and the resin of the conductive paste conductor 73 and the conductive paste conductor 74 are cured, and the copper foil 81 and the copper foil 82 are bonded to the double-sided wiring board 60. At the same time, the wiring layers 64a and 65a of the double-sided wiring board 60 are electrically connected to the copper foils 81 and 82 by the conductive paste conductors 73 and 74.

Next, copper foil 81 and copper foil 82 of multilayer board 90
Are patterned to form a wiring layer 81a and a wiring layer 82a.
To form a multilayer wiring board 100 having an IVH structure in which wiring layers between layers are connected via (see FIG. 2 (h)).

In the multilayer wiring board having the IVH structure as described above, a conductive paste conductor in a second half cured state in which conductive paste is filled into openings is formed, and after lamination, heating and pressing are performed to form a wiring layer with the conductive paste conductor. Is electrically connected to the copper foil, but there is a problem that the electrical connection between the layers is insufficient at a certain frequency.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it has been found that the interlayer connection of each wiring layer can be reliably performed when a multilayer printed wiring board having an IVH structure is manufactured, and the alignment accuracy is improved. An object of the present invention is to provide an excellent method for manufacturing a multilayer printed wiring board.

[0010]

According to the present invention, there is provided a method for producing a multilayer printed wiring board, comprising the following steps (a) to (i). It is. (A) A step of attaching a film 3 on the resin substrate 1 of the resin substrate 11 with copper foil in which the copper foil 2 is formed on the resin substrate 1. (B) a step of irradiating a laser or the like from the film 3 side to form a hole by using the copper foil 2 as a stopper layer to form an opening 4 in the film 3 and the resin substrate 1; (C) a step of cleaning the side wall surface and the copper foil surface of the opening 4; (D) a step of filling the opening 4 with a conductive paste and predrying to form a semi-cured conductive paste conductor 5; (E) a step of removing the film 3 and forming an outer layer substrate 10 in which the projections 5a of the conductive paste conductor 5 protrude from the resin substrate 1 by the thickness of the film 3; (F) a step of manufacturing another outer layer substrate 20 by repeating the steps (a) to (e). (G) A step of laminating the inner layer substrate 30 on which the wiring layers 22 and 23 are formed as a core, with the copper foil 2 and the copper foil 12 of the outer layer substrate 10 and the outer layer substrate 20 facing outward. (H) Pressing under heat and pressure to form the wiring layer 2 of the inner substrate 30
2 and wiring layer 23 and copper foil 2 and copper foil 12 are electrically connected by conductive paste conductor 5 and conductive paste conductor 15 to produce multilayer board 40 (i) on both sides of multilayer board 40 Patterning the copper foil 2 and the copper foil 12 to form a wiring layer 2a and a wiring layer 12a,
A step of producing the multilayer printed wiring board 50;

[0011]

Embodiments of the present invention will be described below. The multilayer printed wiring board of the present invention prepares an outer layer substrate in which a semi-cured conductive paste conductor having a projection is formed on a resin substrate with a copper foil, and the outer layer substrate is formed by using the inner layer substrate on which the wiring layer is formed as a core. Laminate on both sides, press and heat / press to cure the resin board with copper foil and the resin of conductive paste conductor, and make electrical connection between wiring layer and copper foil by conductive paste conductor at the same time, multilayer printed wiring board Is made. By forming a conductive paste conductor having a projection on the resin substrate with copper foil and manufacturing a multilayer printed wiring board by heating / pressing, the interlayer electrical connection between the wiring layer and the copper foil is established. It is possible to obtain a high-density multilayer printed wiring board which can be performed reliably and has excellent alignment accuracy between the outer layer substrate and the inner layer substrate. Note that, as the resin substrate with copper foil, a resin substrate in which copper foil is bonded to a resin substrate, or a resin substrate in which copper foil is coated with resin can be used. The inner substrate may be either a double-sided board or a multilayer board, for example, a multilayer wiring board having an IVH structure.

Hereinafter, a method for manufacturing a multilayer printed wiring board according to the present invention will be described. 1A to 1G are partial cross-sectional views showing one embodiment of a manufacturing process of a multilayer printed wiring board in the order of processes.

First, a polyester film is formed on a resin substrate 1 of a copper-foiled resin substrate 11 in which a copper foil 2 having a thickness of 12 μm is laminated on a resin substrate 1 made of an epoxy resin which is an uncured thermosetting resin. (See FIG. 1A). Here, as the resin substrate with copper foil (APL-B (trade name): manufactured by Sumitomo Bakelite), MC
F-6000 (trade name: manufactured by Hitachi Chemical) or the like can be used.
It is convenient that the thickness of the resin substrate 1 is in the range of 60 to 100 μm and the thickness of the copper foil 2 is in the range of 4 to 35 μm. Film 3
Is used to determine the height of a projection of a conductive paste conductor described later, and a film having a thickness of about 20 μm is used. Further, the film 3 only needs to have an appropriate adhesiveness to the resin substrate 1, and it is preferable that the film 3 has been subjected to a light adhesive bonding process.

Next, a laser (a carbon dioxide gas laser, a UV laser, a YAG laser, etc.) is irradiated from the film 3 side, a hole is formed using the copper foil 2 as a stopper layer, and an opening is formed in the film 3 and the resin substrate 1. 4 (FIG. 1)
(B)).

Next, as a method of cleaning the copper foil surface of the opening 4, there are permanganate treatment, plasma treatment,
Any method such as spraying of the coating particles is preferable. By performing this process, the side wall surface of the opening 4 and the copper foil surface corresponding to the bottom of the opening 4 are cleaned, and the conductive paste is reliably filled. The electrical connection with the device is reliably performed. In particular,
By cleaning the copper foil surface at the bottom of the opening 4, the electrical connection reliability between the conductive paste conductor and the copper foil is improved.

Next, the opening 4 is filled with a conductive paste by screen printing and preliminarily dried to form a semi-cured conductive paste conductor 5 (see FIG. 1C). here,
Copper paste, silver paste, copper paste and carbon-containing paste can be used as the conductive paste.

Next, the film 3 is peeled off and removed to form an outer layer substrate 10 having the conductive paste conductor 5 on which the protrusions 5a protruding from the resin substrate 1 by the amount of the film 3 are formed (FIG. 1 ( d)).

Next, the above steps are repeated to produce an outer layer substrate 20 having a conductive paste conductor 15 having a projection 15a on a resin substrate with a copper foil having a copper foil 12 adhered on a resin substrate 11. .

Next, the outer substrate 10 and the outer substrate 20 having the copper foil 2 and the copper foil 12 on the outside on both sides with the inner substrate 30 having the wiring layer 22 and the wiring layer 23 formed on the insulating substrate 21 as a core, The layers are stacked (see FIG. 1E). Here, the example of the inner layer substrate 30 is a double-sided wiring board. However, the present invention is not limited to this, and a multilayer wiring board having two or more layers can be used as appropriate.

Next, a multilayer board 40 is prepared by heating and pressing at a temperature of 170 to 180 ° C. (see FIG. 1F). In the heating / pressing step, the resin of the resin substrate 1, the resin substrate 11, the conductive paste conductor 5 and the conductive paste conductor 15 is hardened, and at the same time, the wiring of the inner layer substrate 30 is formed by the conductive paste conductor 5 and the conductive paste conductor 15. The layer 22 and the wiring layer 23 are electrically connected to the copper foil 2 and the copper foil 12 of the outer layer substrate.

Next, the copper foil 2 and the copper foil 12 of the multilayer board 40 are patterned to form the wiring layer 2a and the wiring layer 12a, thereby obtaining a multilayer printed wiring board 50 (see FIG. 1 (g)). Here, the wiring layer 2a and the wiring layer 12a above the conductive paste conductors 5 and 15 are drilled by a laser, filled with the conductive paste, and hardened, so that no dent is generated.

[0022]

As described above, according to the production method of the present invention, a conductive paste conductor having a projection is formed on a resin substrate with a copper foil to form an outer layer substrate, and is laminated with an inner layer substrate to form a multilayer printed wiring. Since it is a plate, the positioning accuracy between the conductive paste conductor of the outer layer substrate and the wiring layer of the inner layer substrate is excellent, and good electrical connection can be obtained in all the interlayer connections of each wiring layer. Further, since no dent is formed in the wiring layer above the conductive paste conductor of the outer layer substrate, the wiring layer portion can be used as a land. Therefore, the wiring density can be improved. Further, even in a reliability test such as a temperature cycle test, extremely high interlayer connection reliability can be obtained. Therefore, a multilayer printed wiring board having good electrical connection and extremely high interlayer connection reliability can be manufactured.

[Brief description of the drawings]

FIGS. 1A to 1G are partial cross-sectional views showing one embodiment of a method for manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 2A to 2H are partial cross-sectional views illustrating an example of a manufacturing process of a conventional multilayer printed wiring board having an IVH structure.

[Explanation of symbols]

1. Resin substrate 2, 12, 64, 65, 81, 82 Copper foil 2a, 12a, 22, 23, 64a, 65a, 81a,
82a ... wiring layer 3 ... film 4, 62 ... opening 5, 15, 63, 73, 74 ... conductive paste conductor 5a, 15a ... projection 10, 20 ... outer substrate 11 ... copper foil Resin substrate 21 ... Insulating substrate 30 ... Inner layer substrate 40 ... Multilayer board 50 ... Multilayer printed wiring board 60 ... Double-sided wiring board 61 ... Prepreg resin board 71, 72 ... Conductive paste conductor is formed Prepreg resin substrate 90 Multilayer board 100 Multilayer wiring board

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E346 AA43 CC08 CC32 CC39 DD45 EE06 EE07 EE09 EE13 EE18 FF24 GG08 GG09 GG15 HH07

Claims (1)

[Claims] 1. A method of manufacturing a multilayer printed wiring board, comprising the following steps (a) to (i). (A) A film (3) on a resin substrate (1) of a resin substrate with copper foil (11) in which a copper foil (2) is formed on a resin substrate (1).
A step of sticking. (B) Irradiating a laser or the like from the film (3) side, making a hole using the copper foil (2) as a stopper layer, and forming an opening (4) in the film (3) and the resin substrate (1). Process. (C) a step of cleaning the side wall surface and the copper foil surface of the opening (4). (D) A step of filling the opening (4) with a conductive paste and preliminarily drying to form a semi-cured conductive paste conductor (5). (E) The film (3) is removed to form an outer layer substrate (10) in which the protrusion (5a) of the conductive paste conductor (5) protrudes from the resin substrate (1) by the thickness of the film (3). Process. (F) a step of producing another outer layer substrate (20) by repeating the steps (a) to (e). (G) Copper foil (2) and copper foil (12) of outer layer substrate (10) and outer layer substrate (20) with inner layer substrate (30) having wiring layer (22) and wiring layer (23) formed as a core A step of laminating with the surface outside. (H) By pressing under heat and pressure, the wiring layer (22) and the wiring layer (23) of the inner layer substrate (30) and the copper foil (2) and the copper foil (12) are electrically conductive paste conductor (5) and The multilayer board (4) electrically connected by the conductive paste conductor (15)
Step 0). (I) Copper foil (2) and copper foil (1) on both sides of multilayer board (40)
2) a step of forming a wiring layer (2a) and a wiring layer (12a) by patterning to form a multilayer printed wiring board (50).