JPH1140912A - Full-additive printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a full additive printed wiring board, which has a substrate containing a catalyst for an electroless copper plating and has adhesive layerss formed on the front and rear sides of the substrate and containing a catalyst, which can cope with high-speed manufacturing, high-density mounting and cost reduction by providing a conductive layer having conductive connection hole therein for fixing a surface-mounting part onto the hole. SOLUTION: A through-hole 5D is made in a substrate, a heat-resistive, a conductive past 5 is filled into this hole, conductive layers 5E are provided on the filled connection hole 5D, and a conductive connection hole 5A for electrical connection between the front and rear conducive layers 5E is made. Thereafter formed on the conductive layer 5E on the hole is a small region 5C of the conductive layer for fixing of a surface-mounting part 9 thereonto. Thereby the wiring board can cope with space saving, high-density mounting, high-speed manufacturing and cost reduction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fully additive printed circuit board (CC-41) used for various electronic devices.
The present invention relates to a structure for reducing the space of a conductor layer above a conductive connection hole for making an electrical connection between the front and back conductor layers.

[0002]

2. Description of the Related Art In recent years, while various electronic devices have been adopting advanced packaging technologies, demands have been placed on lowering the price of printed wiring boards, as well as high-density mounting and high electrical characteristics (high-speed operation, etc.). Have been. Hereinafter, a conventional manufacturing process will be described with reference to FIGS. 4A to 4D and FIG.

[0003] First, as shown in FIG. 4 (a), an adhesive layer 12.13 containing a catalyst is applied on the front and back of a glass epoxy substrate 11 containing an electroless copper plating catalyst.

Next, as shown in FIG. 4B, a through-hole 14 is selectively formed using a drill or the like.

[0005] As shown in FIG. 4 (c), a smear is removed, and then an electroless copper plating catalyst is applied in the hole 14.
A permanent resist layer for electroless copper plating having a predetermined thickness is formed on the front and back surfaces of the substrate 11.12.13 by screen printing.
15B is applied and formed.

[0006] As shown in FIG. 4 (d), the adhesive layer 12 is formed by a chemical etching solution such as a chromic acid-sulfuric acid mixed solution.
13 is roughened to form a conductive layer 16 including a through hole 14 and a conductive connection hole 17 by electroless copper plating. At the same time as the formation of the conductive layer 16, a drawer for mounting a surface-mounted component 19 is provided. This is a fully additive printed wiring board 21 according to the related art in which the conductor layer 18 is configured and provided to obtain a large area 18A of the conductor layer.

[0007] Next, as shown in FIG.
In the case where the surface mount type component 19 is mounted on the large area 18A of the conductor layer including the lead-out conductor layer 18 for fixing the surface mount type component 19 and fixed by the cream solder 20A, the reflow soldering method is used. Then, when the paste-like solder 20A melts, the solder 20A flows into the holes of the conductive connection holes 17, and the amount of the solder 20A at both ends of the surface-mounted component 19 becomes non-uniform, which causes a problem in electrical connectivity. Arises

Further, since the large area 18A of the conductor layer is occupied, it is difficult to reduce the space of the conductive connection hole 17 according to the conventional example.
It is.

[0009]

However, in the fully additive printed wiring board 21 according to the prior art, the lead-out conductor layer 1 for fixing the surface-mounted component 19 is not provided.
In order to form 8 outside the conductive connection hole 17, a large area 18A of the conductor layer is provided as shown in FIG. This makes it difficult to reduce the space of the conductor layer 16 in the conductive connection hole 17 and to achieve high-density mounting.
The provision of the lead-out conductor layer for fixing 9 also poses a problem in high-speed operation (high electrical characteristics).

Accordingly, the present invention has been made in view of the above circumstances, and has as its object to reduce the area 5C of the fixing conductor layer of the surface mount type component 9, to reduce the cost, and to increase the density. An object of the present invention is to provide a fully additive printed wiring board 10 which is excellent in mounting and high speed operation.

[0011]

The fully additive printed wiring board 10 of the present invention uses a substrate 1A having a 2.3 layer of an adhesive containing a catalyst on the front and back of a substrate 1 containing an electroless copper plating catalyst. The substrate 1A has a through hole 4 selectively, and the hole 4 is filled with a heat-resistant conductive paste 5;
The photosensitive resist layer for electroless copper plating 6A. Is formed on the front and back surfaces of the substrate 1A. After forming a predetermined thickness of 6B, the wiring conductor layer 5B of a predetermined thickness is formed on the 2.3 adhesive layers on the front and back by electroless copper plating, and at the same time, the conductor layer 5E is integrally formed on the conductive connection hole 5A. Therefore, it is intended to solve the problems of the prior art, such as low cost, high-density mounting, high-speed operation, and the like.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A fully additive printed wiring board having 2.3 layers of an adhesive containing a catalyst on the front and back of a substrate 1 containing an electroless copper plating catalyst of the present invention, using the substrate 1A. The substrate 1A is selectively provided with through-holes 4 by irradiating a laser beam, and the inner wall of the holes 4 is subjected to a smear treatment. Thereafter, the holes 4 are filled with a heat-resistant conductive paste 5, and the inside of the holes 4 is filled. Adhering to the wall surface to form an integral body, and then, on the front and back of the substrate 1A, a photosensitive permanent resist layer (such as SR-3000) 6A for electroless copper plating (temperature: 70 ± 2 ° C., PH: 11, etc.) 6A . After forming the predetermined thickness of 6B,
A filling connection hole in which the heat-resistant conductive paste 5 is filled in the through holes 4 including the wiring conductor layer 5B by electroless copper plating by roughening the adhesive 2.3 layers on the front and back surfaces of the substrate 1A. A conductive layer 5E for fixing the surface-mounted component 9 and a conductive connection hole 5A are also formed on the hole 5D to form a region 5C where the conductive layer is small.
Therefore, it is possible to solve the problems of the prior art, such as high-density mounting and high electric characteristics (high-speed operation, etc.), in addition to low cost.

[0013]

1 and 2 showing an embodiment of the present invention.
A specific description will be given based on (a) to (c) and FIGS. 3 (d) to (g).

[0014]

Embodiment 1 First, FIG. 2A shows an adhesive 2.3 containing a catalyst on the front and back of a substrate 1 containing an electroless copper plating catalyst.
Using a glass epoxy substrate 1A provided with a layer (thickness 1.44t, trade name ACL-E-168 manufactured by Hitachi Chemical Co., Ltd.)
The substrate 1A has a low induction ratio of 5.4 due to high-speed operation and the like.
Hereinafter, the material is a plating solution contamination of 0.5 mA / cm ² or more and a solder heat resistance of 260 to 262 ° C.

Next, as shown in FIG.
The φ1 through hole 4 is selectively formed in the substrate 1A of FIG. The method of drilling this hole 4 is
For example, as a laser beam, a carbon dioxide laser, YAG
Although it is a laser and an excimer laser, in the embodiment of the present invention, a carbon dioxide laser is preferable,

The diameter of the through hole 4 is set to 0.045 to 0.045.
The preferred diameter in the range of 0.4 mm is 0.1 to 0.2 mm, and the inner wall roughness of the hole 4 is in the range of 5 to 40 μm, more preferably in the range of 15 to 30 μm.

Next, as shown in FIG. 2C, the inner wall of the through hole 4 is subjected to a smear treatment, and then a heat-resistant conductive paste 5 made of a conductive filler and a heat-resistant thermosetting resin is screened in the hole 4. Fill using a printing squeegee,
Temporarily dry at a temperature of about 80 ° C. Then, about 10 kg /
After applying a pressure of ² cm ² to increase the packing density of the heat-resistant conductive paste 5, the unnecessary heat-resistant conductive paste 5 was removed and flattened on the front and back surfaces using a belt grinder. After a while
The main drying is performed in a continuous wicket drying oven at a temperature of 150 ° C.

The heat-resistant conductive paste 5 is composed of a conductive filler and a heat-resistant thermosetting resin. The heat-resistant thermosetting resin includes, for example, an epoxy resin, a modified epoxy resin, a modified phenolic resin, and a modified polyimide resin. And at least one selected from these may be used.

The conductor filler is, for example, copper powder, nickel powder, palladium powder, platinum powder, or the like, and may be at least one selected from these.
In the range of 0.18 to 35 μm, more preferred particle size is 4 to
In the range of 10 μm, the most preferred particle size is on the order of about 7.0 μm. When the average particle size is more than 35 μm, the contact between the conductive fine powders is insufficient, and the electrical density is deteriorated, and the conductivity is reduced. When the average particle size is less than 0.18 μm, the contact resistance is increased. Therefore, the conductivity is lowered, so that any of them is not suitable, and the shape of the particle size is preferably spherical or flake.

The content of the conductor filler is 50
In the range of ~ 96 wt%, the remainder becomes heat-resistant thermosetting resin,
When the preferred content is 85 to 90% by weight, higher electric conductivity can be maintained.

Further, the content of the conductor filler is 50 wt.
If the content is less than 96%, the conductivity is lowered due to the deterioration of the deposition property of the electroless copper plating. If the content exceeds 96% by weight, the adhesion between the heat-resistant thermosetting resin and the conductor powder (copper powder, nickel powder, palladium powder, platinum powder) And none are suitable.

Next, as shown in FIG. 3 (d), the photosensitive permanent resist layer 6A. 6B is formed less than about 40 μm.

The photosensitive permanent resist layer 6A.
6B is, for example, a negative type photosensitive film manufactured by Hitachi Chemical Co., Ltd., PHOTEC SR-3000, which withstands the temperature of the electroless copper plating solution: 70 ± 2 ° C. and PH: 11.0. .

The permanent resist layer 6A. 6BS
The developer of R-3000 is diethylene glycol, monobutyl ether: 200 ± 20 ml / l, water: 800 ml /
1, borax: 8 ± 2 g / l, temperature: 40 ± 2 ° C., hydraulic spray pressure: 1.0 to 1.5 kgf / cm ² , water temperature: 10 to 35
° C, drying: 70 to 90 ° C for 5 to 10 minutes, and post-exposure with a high-pressure mercury lamp: 1 to ² J / cm ² .

As shown in FIG. 3E, the surface is roughened.
Conductive layer (5E) for fixing surface-mounted component (9) on hole of filling connection hole (5D) including wiring conductor layer (5B) by electroless copper plating
Is formed to a thickness exceeding 35 μm, and the conductive connection hole 5A of the present invention is formed.
Is obtained, a small area 5C of the conductor layer 5E for fixing the surface-mounted component 9 can be formed, and a fully additive printed wiring board 10 capable of high-density mounting, high speed, and low cost
It is.

Next, as shown in FIG. 3F, the solder paste 7A. 7B to about 7
Print and form about 0 μm.

Next, as shown in FIG. 3 (g), the front and back sides of FIG. 3 (f) are subjected to fading at a temperature of 340 ° C. for about 0.5 minute, and only the wiring conductor layer 5B and the hole conductor layer 5E are formed. And a full additive printed wiring board 10 on which a solder film 8 is formed.

Next, FIG. 1 shows an embodiment of the present invention, in which a surface-mounted component 9 is filled. A solder coating 8 is formed on the conductor layer 5E on the connection hole 5D, and the surface-mounted component 9 is fixed thereto. In this case, the lead conductor layer 18 for fixing the component 19 in the prior art is no longer required, and a region 5C with a smaller conductor layer is also obtained, enabling high-density mounting and high-speed operation. Moreover, since the heat-resistant conductive paste 5 is filled in the through-holes 4 to form the conductive connection holes 5A, the full-additive printed wiring board 10 can be made available at a low cost.

[0029]

According to the present invention, the heat-resistant conductive paste 5 filled in the through-hole 4 and the conductive layer 5E on the filling connection hole 5D are formed, and the front and back of the conductive layer 5E are electrically connected. By forming the conductive connection hole 5A, the lead-out conductor layer (land) 18 for fixing the surface-mounted type component 9 is not required, which enables high-speed operation and the conductive connection hole 5A.
The component 9 can be directly fixed to the upper conductive layer 5E, thereby obtaining an area 5C with a small conductive layer, enabling a small space and high-density mounting, and a heat-resistant conductive paste 5 in the through hole 4. , And the front and back conductor layers can be electrically connected, so that the inner wall of the through hole 4 does not require electroless copper plating.
Cost reductions can also be possible, and the effect of contributing to industry is great.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

FIGS. 2A to 2C are cross-sectional views illustrating a manufacturing process of the present invention.

FIGS. 3 (d) to 3 (g) are cross-sectional views showing a manufacturing process of the present invention.

4A to 4D are cross-sectional views showing a conventional manufacturing process.

FIG. 5 is a schematic explanatory view in which surface mounting components are mounted on a fully additive printed wiring board according to the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate (containing a catalyst) 1A ... Substrate (including 1 and 2.3) 2.3 ... Adhesive (containing a catalyst) 4 ... Through hole 5 ... Heat resistant conductive paste 5A ... Conductive connection hole 5B ... Wiring conductor layer ( Land) 5C
... Conductor layer small area 5D. Filled connection hole 5E. On-hole conductor layer (land) 6A. 6B: permanent resist layer (photosensitive) 7A. 7B ...
Solder paste 8 ... Solder coating 9 ... Surface mount type component 9 ... Full additive printed wiring board of the present invention 11 ...
Substrate (containing catalyst) 12.13 Adhesive (containing catalyst) 14 ... Through-hole 15A. 15B: Permanent resist layer 16: Conductor layer (land) 17: Conductive connection hole 18: Lead-out conductor layer (land) 18A: Large area of conductor layer 19: Surface mount type component
20A: Solder 20B: Poor solder flow 21: Fully additive printed wiring board according to the prior art

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] September 19, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A fully additive printed wiring board having 2.3 layers of an adhesive containing a catalyst on the front and back of a substrate 1 containing an electroless copper plating catalyst of the present invention, using the substrate 1A. The substrate 1A is selectively provided with through-holes 4 by irradiating a laser beam, and the inner wall of the holes 4 is subjected to a smear treatment. Thereafter, the holes 4 are filled with a heat-resistant conductive paste 5, and the inside of the holes 4 is filled. A photosensitive permanent resist layer for electroless copper plating (temperature: 70 ± 2 ° C., PH: 12,0, etc.) (e.g., SR-3000) ) 6A. After forming a predetermined thickness of 6B, the adhesive 2.3 layer on the front and back surfaces of the substrate 1A is roughened,
The conductive layer 5E for fixing the surface-mounted component 9 is also formed on the filling connection hole 5D in which the heat-resistant conductive paste 5 is filled in the through hole 4 including the wiring conductor layer 5B by electroless copper plating. And a conductive connection hole 5A can be formed to form a region 5C with a small conductor layer, so that it is possible to solve the problems of the prior art such as high-density mounting and high electric characteristics (high-speed operation, etc.) as well as low cost. It is.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0023

[Correction method] Change

[Correction contents]

The photosensitive permanent resist layer 6A.
6B is, for example, trade name manufactured by Hitachi Chemical, photosensitive film negative, in Fotekku SR-3000, the temperature of the electroless copper plating solution: 70 ± 2 ℃, PH: 12.0 Tolerant to <br />.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05K 3/24 H05K 3/24 C

Claims (3)

[Claims] 1. An adhesive containing a catalyst (2) on the front and back of a substrate (1) containing an electroless copper plating catalyst. (3)
In a full additive printed wiring board having a layer,
Using the substrate (1A), the substrate (1A) has a through-hole (4), and the heat-resistant conductive paste (5) is filled and integrated into the hole (4) to form a filling connection hole (5D). Thereafter, a photosensitive permanent resist layer for electroless copper plating (6A) is formed on the front and back surfaces of the substrate (1A). (6B) is formed to a predetermined thickness, and then the front and back adhesives (2). (3) A conductive layer (5A) having a predetermined thickness is formed on the layer, and at the same time, a conductive layer (5A) is formed by integrally forming the conductive layer (5E) on the connection hole (5D). Fully additive printed wiring board (1
0). 2. The heat-resistant conductive paste (5) according to claim 1, comprising a heat-resistant thermosetting resin and a conductive filler, wherein the heat-resistant thermosetting resin is an epoxy resin, a modified epoxy resin, a modified phenolic resin. , Modified polyimide resin or the like, and at least one selected from these. The conductive filler may be at least one selected from gold powder, copper powder, and nickel powder. In the range of 2 to 40 μm, in a flake or spherical shape, and the content of the conductor filler is:
A fully additive printed wiring board (10), characterized in that the remainder is made of the heat-resistant thermosetting resin in the range of 60 to 96% by weight. 3. The through hole (4) according to claim 1, wherein:
Has a hole (4) diameter in the range of 0.045 to 0.4 mm, and an inner wall roughness of the through hole (4) in the range of 5 to 40 μm. A fully additive printed wiring board (1
0).