JPH09326562A - Circuit board and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the reliability of a circuit board comprising three or more layers by forming an insulating layer on the wiring pattern on the surface of an insulating board, filling openings in the insulating layer with a setting conductive member, thereafter flattening the workpiece, forming a plating layer thereon, and etching it to form a second wiring pattern. SOLUTION: An insulating layer 10 is formed on a first wiring pattern 6 containing through holes 2 penetrating an insulating board 1, and openings 11 are formed to connect the front side and rear side of the insulating board 1. The openings 11 are filled with copper paste as a setting conductive member 12, and the surface comprising the insulating layer 10 and the cured body of the setting conductive member 12 is flattened by grinding. A copper plate layer 20 is formed on the flattened surface of the insulating layer containing the copper paste 12 by plating. A resist pattern is formed on the surface of the plating layer, and etching is performed. Then, the etching resist is stripped to obtain a second wiring pattern 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board manufacturing method and a circuit board. Conventionally, when a component is mounted on a printed circuit board, it has been usual to place the circuit component on the surface of the component, insert the lead of the circuit component into the through hole, and solder it. However, in recent years, the packaging density of circuit components has been improved, the wiring patterns have been miniaturized accordingly, and the number of pins of the circuit components has increased significantly. With the increase in the density of such circuit boards, printed circuit boards having three or more layers have been used, and multilayer circuit boards that are easy to manufacture are required.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing a conventional process for manufacturing a circuit board. In (a), 1 is an insulating substrate (printed substrate), 2 is a through hole penetrating the front surface and the back surface of the insulating substrate 1, and 3 is a copper foil formed on the front surface and the back surface of the insulating substrate 1. The insulating substrate 1 has a thickness of 1.2 mm, for example.
Glass epoxy substrates are used. The through holes 2 are drilled between the first layer circuit patterns made of the copper foil 3. The diameter of the through hole 2 is, for example, about 0.4 mm.

Next, as shown in (b), the through hole 2 is filled with a copper paste 4 as a curable conductive member by a screen printing method so as to protrude by 0.25 mm from the wiring pattern. With this copper paste, the wiring patterns on the front surface and the back surface of the insulating substrate 1 are electrically connected. Next, the copper paste 4 is 50 in an air oven.
It is cured under conditions of 30 minutes at 180 ° C. and 60 minutes at 180 ° C.

Next, the surface composed of the cured product of the circuit pattern (copper foil) 3 and the copper paste 4 is smoothed by sequentially using the 200th buff and the 360th buff as shown in (c). Grind. Next, as shown in (d), electroless plating is performed on the smoothed conductive layer surface including the through hole portion,
Electrolytic plating is performed to form a plating layer (plating layer) 5 having a thickness of 15 μm. Then, an etching resist is laminated on the surface of the plating layer 5, exposed and developed to form a resist pattern, and after etching with a ferric chloride etching solution, the etching resist is peeled off,
A first wiring pattern 6 as shown in (e) is formed.

[0005]

The above-mentioned conventional technique has an advantage that it is not necessary to plate through holes, but it cannot manufacture a circuit board having three or more layers.

The present invention has been made in view of the above problems, and an object thereof is to provide a method of manufacturing a circuit board having three or more layers and high reliability, and a circuit board.

[0007]

According to a first invention for solving the above-mentioned problems, a front side and a back side of an insulating substrate are connected by a first curable conductive member filled in a through hole, and a first curable conductive member is formed on the surface thereof. In which the wiring pattern is formed, a first step of forming an insulating layer on the first wiring pattern and forming an opening at a predetermined position of the insulating layer; and a second step of forming the opening in the opening. In the second step of filling the curable conductive member, the third step of flattening the second curable conductive member, and then forming a plating layer thereon, and etching the plating layer. And a fourth step of forming a predetermined second wiring pattern.

According to the structure of the present invention, the insulating layer is formed on the surface of the conductive layer formed of the first wiring pattern, the opening is provided in the insulating layer, and the opening is filled with the curable conductive member to form the through layer. By maintaining the electrical connection with the hole, the second wiring pattern can be further formed on the first wiring pattern, and the electrical connection between the first wiring pattern and the second wiring pattern can be achieved. The connection can be secured. Then, a highly reliable circuit board having three or more layers can be manufactured.

In this case, the circuit board having an arbitrary number of layers is characterized by repeating the first to fourth steps. According to the configuration of the present invention, by repeating the first to fourth steps, a circuit board having an arbitrary number of layers can be created, and the created circuit board is highly reliable. Become.

A second invention for solving the above-mentioned problems is to provide a through hole penetrating the front and back of the insulating substrate, a first curable conductive member filling the through hole, and the front and back of the insulating substrate. A first wiring pattern formed on the first wiring pattern, an insulating layer formed on the first wiring pattern, an opening formed at a predetermined position of the insulating layer, and a second filling the opening. And a second wiring pattern formed on the insulating layer including the second curable conductive member.

According to the structure of the present invention, the insulating layer is formed on the surface of the conductive layer formed of the first wiring pattern, the opening is provided in the insulating layer, and the opening is filled with the curable conductive member to form the through layer. By maintaining the electrical connection with the hole, the second wiring pattern can be further formed on the first wiring pattern, and the electrical connection between the first wiring pattern and the second wiring pattern can be achieved. The connection can be secured. Then, a highly reliable circuit board having three or more layers can be manufactured.

In this case, the insulating layer, the opening, the second curable conductive member, and the second wiring pattern are added as necessary to form a circuit board having an arbitrary number of layers. Is characterized by.

According to the structure of the present invention, the insulating layer,
A circuit board with an arbitrary number of layers can be created by adding an opening, a second curable conductive member, and a second wiring pattern as needed, and a highly reliable circuit board is provided. can do.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a flowchart showing an embodiment of the method of the present invention. The method of the present invention is the first method in which the front and back of the insulating substrate are filled in through holes.
Which is connected by the curable conductive member and has a first wiring pattern formed on its surface, an insulating layer is formed on the first wiring pattern, and an opening is formed at a position corresponding to the through hole. First step of forming, second step of filling the second curable conductive member into the opening, and flat processing of the second curable conductive member, and then forming a plating layer thereon. And a fourth step of etching the plated layer to form a predetermined second wiring pattern. Then, by adopting such a sequence, it is possible to provide a highly reliable method of manufacturing a circuit board having three or more layers and a circuit board.

2 and 3 are views showing an embodiment of a process for manufacturing a circuit board by the method of the present invention. The same components as those in FIG. 5 are denoted by the same reference numerals. In the present invention, the steps up to forming the first wiring pattern on both surfaces of the insulating substrate 1 are the same as those shown in FIG. Therefore, (a) of FIG. 2 is the same as that shown in (e) of FIG.

In (a) and (a), 1 is an insulating substrate made of glass epoxy or the like, 2 is a through hole penetrating the insulating substrate 1, and 4 is a first curable conductive member filled in the through hole 2. A certain copper paste. Reference numeral 6 is a first wiring pattern formed on the front and back surfaces of the insulating substrate 1.

Here, the components of the copper paste 4 will be described. A copper paste having the following composition was used as the copper paste. That is, as a binder component, 69 parts by weight of undecyl glycidyl ether per 100 parts by weight of bisphenol A diglycidyl ether having an epoxy equivalent of 173 g / equivalent and 100 parts by weight of the bisphenol A diglycidyl ether, and a novolak type phenol resin as a curing agent are used. 5
7 parts by weight and, as copper powder, 400 parts by weight of dendritic copper powder having an average particle size of 10.5 μm was added to the binder, and further 2
-Ethyl-4-methylimidazole, binder 10
What added 2.8 weight part with respect to 0 weight part was knead | mixed for 45 minutes with a three roll, and the copper paste was prepared.

In order to form an insulating layer on the first layer wiring pattern 6 including the through holes 2 from the state shown in (b) and (a), a photosensitive insulating resist (Probicoat 5000:
Product name, made by Nippon Paint Co., Ltd.), dried, exposed,
After developing, it is thermally cured to form the insulating layer 10.
Then, the opening 11 having a diameter of 0.15 mm is formed at a portion (that is, a portion corresponding to the through hole) where electrical connection is required between the front surface and the back surface of the insulating substrate 1 or another predetermined position.

(C) Next, the opening 11 is filled with a copper paste as the second curable conductive member 12. As a component of the copper paste 12, a copper paste NF-2000 manufactured by Tatsuta Electric Wire Co., Ltd. in which a binder is a resol-type phenol resin is used. Specifically, the copper paste 12 is filled by a screen printing method so as to protrude from the insulating layer 10 by 0.05 mm, and the first temperature is set to 230 ° C. in a belt conveyor type far infrared furnace and the curing time is set to 6 minutes. The second copper paste 12 is hardened.

(D) Insulating layer 10 and curable conductive member 12
The surface composed of the cured product of No. 360 buff and 6
Use No. 00 buff sequentially to grind smoothly. As a result, the second copper paste 12 does not protrude from the insulating layer 10 and becomes flat.

(E) Next, the surface of the smoothed insulating layer containing the copper paste 12 is subjected to electroless plating or electroplating to form a copper plating layer (plating layer) 20 having a thickness of 10 μm.

(F) Next, an etching resist is laminated on the surface of the plating layer, exposed and developed to form a resist pattern, and after etching with a ferric chloride etching solution, the etching resist is peeled off. Thereby, the second layer wiring pattern 21 is formed. This makes it possible to obtain a multilayer circuit board having a wiring pattern of two layers on each of the front surface and the back surface of the insulating substrate 1 and a total of four layers.

According to the present invention, the front and back of the insulating substrate are connected by the first curable conductive member filled in the through hole, and the first wiring pattern is formed on the surface of the first curable conductive member. Form an insulating layer on the wiring pattern of 1,
A first step of forming an opening at a predetermined position of the insulating layer, and a second step of filling the opening with a second curable conductive member
And the step of flattening the second curable conductive member,
The conductive layer surface formed of the first wiring pattern is constituted by a third step of forming a plating layer thereon and a fourth step of etching the plating layer to form a predetermined wiring pattern. An insulating layer is formed on the insulating layer, an opening is formed in the insulating layer, and the opening is filled with a curable conductive member to maintain electrical connection with the through hole.
It is possible to further form a second wiring pattern on the wiring pattern, and it is possible to ensure electrical connection between the first wiring pattern and the second wiring pattern.
Then, a highly reliable circuit board having three or more layers (here, four layers) can be manufactured.

In the above-described embodiment, the case where a circuit board having a total of four layers, two layers each on the front surface and the back surface of the insulating substrate, is prepared as an example. However, the present invention is not limited to this. The process of forming the insulating layer, forming an opening in the insulating layer, filling the opening with a curable conductive member, smoothing it, and forming a plating layer on the surface of the insulating substrate 1
By providing on the front surface and the back surface of or any of the surfaces,
A circuit board having an arbitrary number of layers can be produced, and the produced circuit board is highly reliable.

FIG. 3F is a view showing the structure of the completed four-layer circuit board. In the figure, 2 is an insulating substrate 1.
Through holes 3 and 3 are copper foils formed on the front surface and the back surface of the insulating substrate 1, respectively, and 4 is a copper paste (first copper conductive film) filling the through holes 2 (first copper foil). Copper paste), 6 is a first wiring pattern formed on the front and back of the insulating substrate 1, 10 is an insulating layer formed on the first wiring pattern 6, and 11 is the insulating layer 1.
0 is an opening formed at a predetermined position, 12 is the opening 1
1 is a copper paste (second copper paste) as a second curable conductive member, and 21 is a second wiring formed on the insulating layer including the second curable conductive member 12. It is a pattern.

By thus configuring the circuit board, the insulating layer is formed on the surface of the conductive layer formed of the first wiring pattern, the insulating layer is provided with an opening, and the opening is filled with the curable conductive member. By maintaining the electrical connection with the through hole, a second wiring pattern can be further formed on the first wiring pattern, and furthermore, the first wiring pattern and the second wiring pattern can be formed. The electrical connection of the can be ensured. Then, a highly reliable circuit board having three or more layers can be manufactured.

In the above-described embodiment, the case where the second layer is formed on both surfaces of the insulating substrate 1 is taken as an example, but the second layer can be formed on either the front surface or the back surface. In this case, the circuit board has three layers.

Further, in the above-described embodiment, the case where a circuit board having a total of four layers, two layers each on the front surface and the back surface of the insulating substrate 1 is realized is taken as an example. However, the present invention is not limited to this, and the insulating layer 10 and the opening 1
1, the second curable conductive member 12, and the second wiring pattern 21 are added to the front surface and / or the back surface of the insulating substrate 1 or any one of the surfaces thereof as necessary to form a circuit board having an arbitrary number of layers. Can be created.

[0029]

EXAMPLE The resistance between the wiring patterns 21 located on the front and back of the multilayer circuit board obtained as described above and connected to a common through hole was measured, and as a result, the average was 23 mΩ.
Met. In addition, the thermal shock test of JIS C-5012 (-65 ° C ×) using a test pattern including between the wiring patterns located on the front and back sides of the multilayer circuit board as shown in FIG.
30 minutes ← → 125 ° C x 30 minutes: In Fig. 4, in (1) and (1), (2) and (2), (3) and (3) resistance measurement), the number of cycles exceeds 100 times. However, there was continuity of the test pattern including between the wiring patterns 21 located on the front and back sides of the multilayer circuit board, and there was almost no increase in electrical resistance thereafter.

[0030]

As described above in detail, according to the first aspect of the invention, the front and back of the insulating substrate are connected by the first curable conductive member filled in the through hole, and the first and second curable conductive members are connected to the surface of the first curable conductive member. 1
In which the wiring pattern is formed, a first step of forming an insulating layer on the first wiring pattern and forming an opening at a predetermined position of the insulating layer; and a second step of forming the opening in the opening.
In the second step of filling the curable conductive member, the third step of flattening the second curable conductive member, and then forming a plating layer thereon, and etching the plating layer. And a fourth step of forming a predetermined second wiring pattern, whereby an insulating layer is formed on the surface of the conductive layer formed of the first wiring pattern, an opening is provided in the insulating layer, and the opening is formed. The second wiring pattern can be further formed on the first wiring pattern by filling the portion with the curable conductive member and maintaining the electrical connection with the through hole,
Moreover, it is possible to ensure the electrical connection between the first wiring pattern and the second wiring pattern. Then, a highly reliable circuit board having three or more layers can be manufactured.

In this case, by repeating the first to fourth steps, a circuit board having an arbitrary number of layers can be produced, and the produced circuit board becomes highly reliable. .

According to the second invention, through holes penetrating the front and back of the insulating substrate, the first curable conductive member filling the through holes, and the front and back of the insulating substrate are formed. A first wiring pattern, an insulating layer formed on the first wiring pattern, an opening formed at a predetermined position of the insulating layer, and a second curable conductive material filling the opening. And a second wiring pattern formed on the insulating layer including the second curable conductive member to form an insulating layer on the surface of the conductive layer formed of the first wiring pattern. Then, by providing an opening in the insulating layer and filling the opening with a curable conductive member to maintain electrical connection with the through hole, a second wiring pattern is further formed on the first wiring pattern. And the first wiring pattern and the second wiring pattern. The electrical connection between the wiring pattern can be ensured. Then, a highly reliable circuit board having three or more layers can be manufactured.

According to the present invention, since the surface of the circuit board can be flattened, the component can be mounted at the position corresponding to the opening. In addition, when it is necessary to directly plate the opening, the plating solution may enter between the insulating layer and the copper foil to cause peeling, but the present invention can solve such a problem.

As described above, according to the present invention, it is possible to provide a highly reliable method of manufacturing a circuit board having three or more layers and a circuit board.

[Brief description of drawings]

FIG. 1 is a flowchart showing an embodiment of the method of the present invention.

FIG. 2 is a diagram showing an example of an embodiment of a manufacturing process of a circuit board according to the method of the present invention.

FIG. 3 is a diagram showing an example of an embodiment of a manufacturing process of a circuit board according to the method of the present invention.

FIG. 4 is an explanatory diagram showing a structure of a circuit board for a thermal shock test.

FIG. 5 is a diagram showing a manufacturing process of a conventional circuit board.

[Explanation of symbols]

 1 Insulating Substrate 2 Through Hole 3 Copper Foil 4 First Copper Paste (Curable Conductive Member) 6 First Wiring Pattern 10 Insulating Layer 11 Opening 12 Second Copper Paste (Curable Conductive Member) 20 Plating Layer 21 2 wiring patterns

Claims (4)

[Claims] 1. A front surface and a back surface of an insulating substrate are connected by a first curable conductive member filled in a through hole, and a first wiring pattern is formed on the surface of the first wiring pattern. A first step of forming an insulating layer on the insulating layer and forming an opening at a predetermined position of the insulating layer; a second step of filling the opening with a second curable conductive member; After the flattening of the curable conductive member No. 2 is performed, a third step of forming a plating layer thereon and a fourth step of etching the plating layer to form a predetermined second wiring pattern are performed. A method of manufacturing a configured circuit board. 2. The method for manufacturing a circuit board according to claim 1, wherein the circuit board having an arbitrary number of layers is created by repeating the first step to the fourth step. 3. A through hole penetrating the front and back of the insulating substrate, a first curable conductive member filling the through hole, and a first wiring pattern formed on the front and back of the insulating substrate. An insulating layer formed on the first wiring pattern, an opening formed at a predetermined position in the insulating layer, a second curable conductive member filling the opening, And a second wiring pattern formed on the insulating layer including the curable conductive member. 4. A circuit board having an arbitrary number of layers is created by adding the insulating layer, the opening, the second curable conductive member, and the second wiring pattern as needed. The circuit board according to claim 3.