JPH07307542A - Wiring board with built-in resistor and manufacture - Google Patents

Abstract

PURPOSE:To realize a wiring board with a built-in resistor which can enhance wiring density and possessed of a flat region where a resistor is printed by a method wherein the resistor is provided in a region where a ground is flat. CONSTITUTION:A pattern formed of insulating layers 2a which are opposed to each other and formed as thick as a first conductor 5 is formed on a base board 1, copper plating catalyst 3 is applied thereon, and an insulating undercoat 4 as thick as the sum of the thicknesses of the insulating layer 2a and the first, conductor 5 is provided between the insulating layers 2a. A gap 11 serving as a region where a silver electrode is formed is provided between the insulating undercroat 4 and the insulating layer 2a, the insulating layer 2a and the gap 11 are subjected to a selective chemical copper plating process for the formation of the first conductor 5 equal in thickness to the insulating layer 2a. Therefore, a resistor silver electrode 6 is so formed in the gap 11 as to be flush with the undercoat, 4 by printing to form a flat resistor printed surface 13, and a resistor 7 is formed by printing, whereby the resistor 7 is restrained in both sagging and bleeding at printing and improved in mount density.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board with a built-in resistor, which is suitable for miniaturization of electronic devices and high-density mounting of electronic parts, and a manufacturing method thereof.

[0002]

2. Description of the Related Art As electronic devices have become smaller and more densely mounted, wiring boards have become smaller, lighter and more densely wired. Along with this, a wiring board with a built-in resistor is being developed in which a resistor that has been conventionally surface-mounted is formed as a printed resistor on the inner layer of the wiring board. As a result, the mounting area of the resistor is reduced and high density wiring can be realized. A conventional wiring board with a built-in resistor has been manufactured by a build-up method as disclosed in JP-A-1-42895. This is a method in which a printed resistor is formed on a base substrate, an insulating paste is applied on the resistor, and a conductor is formed on the insulating layer with a metal paste such as copper. The build-up method is a cost effective method for manufacturing wiring boards in the future.

These conventional techniques will be described with reference to the drawings.
FIG. 6 is a sectional view of a conventional wiring board with a built-in resistor. In this figure, 1 is a base substrate which is a base, 4 is an undercoat which serves as an insulator for separating the first layer conductor 5,
Reference numeral 5 is a first layer conductor to be a wiring pattern, 6 is a silver electrode for resistance, 7 is a resistor, 8 is an overcoat which is an insulator, 9
Is the second layer conductor.

[0004]

As can be seen from this figure, since the resistor silver electrode 6 is formed on the undercoat 4, the resistor printed portion is not flat. For this reason, the printability of the resistor 7 is poor, and the resistor spreads,
There is a problem that bleeding occurs during repeated printing and high density wiring cannot be performed. Further, due to the sagging, the thickness of the resistor 7 becomes non-uniform, so that the resistance value varies. Therefore, unlike the design value, there is a problem in that reliability is impaired.

Further, when heat shrinking after printing the resistor 7 or when handling the wiring board in the device, the resistor 7 is moved to the stepped portion.
Stress concentrates. For this reason, there is a possibility that cracks may occur, leading to reduced reliability and malfunction due to changes in resistance value. Further, the resistor-arranged portion is formed by stacking three stages of the first-layer conductor 5, the silver electrode 6, and the resistor 7, and a step difference of three stages is generated as compared with the non-wiring portion. Therefore, the overcoat 8 also does not become flat. Therefore, when the second layer conductor is formed, the printability is deteriorated when the second layer conductor using a metal paste such as copper or the resistor is formed by printing. Therefore, similarly, sagging and blurring occur, and there is a problem that a high-density multilayer wiring board cannot be obtained.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art. The resistance value of the resistor is excellent in stability and reliability, high-density wiring, and a built-in resistor capable of forming a multilayer structure. It is an object of the present invention to provide a structure of a wiring board, a manufacturing method thereof, and an electronic device in which electronic parts are mounted on the wiring board.
A first specific object is to provide a structure of a wiring board with a built-in resistor in which a printed portion of a resistor is flat and a manufacturing method thereof. The second purpose is to form an insulating layer on the resistor formed by printing, and to form a further upper layer, in a multilayer wiring board,
(EN) A structure of a multi-layer substrate having a flat upper layer forming surface and a manufacturing method thereof.

[0007]

In order to achieve the above object, a wiring board with a built-in resistor according to the present invention includes a base substrate, an insulating layer provided separately on the base substrate, and an insulating material between these insulating layers. A resistor built-in wiring board including an undercoat formed by using the resistor, at least a resistor provided on the undercoat, and an electrode connected to the resistor, wherein the resistor has a flat base layer. It is arranged in.

More specifically, the wiring board with a built-in resistor according to the present invention has an undercoat having the same film thickness as the insulating layer, separated from each insulating layer by the gap, and the insulating layer and the gap. , A conductor formed continuously by using metal plating and having a thickness smaller than that of the insulating layer, a resistance electrode formed in the gap with metal paste at the same height as the undercoat, and a resistance electrode The resistor is formed on a flat surface that is continuous with the upper surface and the upper surface of the undercoat, and has the same height as the conductor on the insulating layer.

As a method of manufacturing this wiring board with a built-in resistor,
A step of separately providing an insulating layer on the base substrate so as to face at least the resistor formation region, and a step of applying a metal plating catalyst on the base substrate and the insulating layer,
A step of forming an undercoat using an insulating material, which has a gap portion and has the same thickness as that of the insulating layer, between the insulating layers facing each other; A step of forming a one-layer conductor, a step of printing and forming a resistance electrode by using a metal paste in the gap so that there is no step difference with the undercoat, and a continuous flat surface of the resistance electrode upper surface and the undercoat upper surface. And a step of forming a resistor on the insulating layer so as to have the same height as that of the first layer conductor on the insulating layer.

The wiring board with a built-in resistor according to the present invention comprises an undercoat formed of an insulating material and having the same thickness as the insulating layer, separated from each insulating layer by a gap, and an undercoat formed on the insulating layer. A conductor continuously formed at the same height as the undercoat by using metal plating in the gap, a thin film resistance electrode formed by metal plating on the upper surface of the conductor, an undercoat, and an undercoat. The resistor is formed on a continuous flat surface on the resistive thin-film electrode area on substantially the same plane as the coat, and at the same height as the conductor on the insulating layer.

As a method of manufacturing this wiring board with a built-in resistor,
A step of separately providing an insulating layer on the base substrate so as to face at least the resistor formation region, and a step of applying a metal plating catalyst on the base substrate and the insulating layer,
A step of forming an undercoat using an insulating material, which has a gap portion and has the same thickness as that of the insulating layer between the insulating layers facing each other, and metal plating is performed on the insulating layer and the gap portion. A step of forming the first layer conductor so that the height formed on the substrate is the same as the undercoat,
On the upper surface of the first layer conductor, the step of forming a thin film resistance electrode by metal plating, on the thin film resistance electrode area on the same plane as the undercoat on the base substrate, and on a continuous flat surface on the undercoat. , Selectively forming a resistor so as to have the same height as the first-layer conductor on the insulating layer.

Furthermore, the wiring board with a built-in resistor according to the present invention is an undercoat formed by using an insulating material which is between insulating layers and which is separated from each insulating layer by a gap and has a thickness larger than that of the insulating layer. And a conductor and a metal-plated gap part continuously formed by metal plating on the insulating layer and the gap part so that the height on the insulation layer becomes the same height as the undercoat. And a resistor electrode formed by using a metal paste at the same height as the undercoat, and a resistor formed on a continuous flat surface of the resistor electrode upper surface and the undercoat upper surface.

As a method of manufacturing this wiring board with built-in resistors,
A step of separately providing an insulating layer on the base substrate so as to face at least the resistor formation region, and a step of applying a metal plating catalyst on the base substrate and the insulating layer,
Between the insulating layers facing each other, a step of forming an undercoat using an insulating material having a gap and having a film thickness thicker than that of the insulating layer, and an undercoat by metal plating on the insulating layer and the gap. The step of forming the first-layer conductor so as to have the same height as that of the step 1, the step of printing the resistance electrode so that there is no step between the undercoat and the undercoat by using the metal paste in the gap, and the top surface of the resistance electrode. And a step of forming a resistor on a flat surface continuous with the upper surface of the undercoat.

Alternatively, a step of separately providing an insulating layer on the wiring portion on the base substrate so as to face at least the resistor forming region, and a step of applying a metal plating catalyst on the base substrate and the insulating layer. , Between the insulating layers facing each other, having a gap and having the same thickness as the edge layer,
A step of forming an undercoat using an insulating material, and a resistor formed later on the non-wiring part on the base substrate,
A step of forming a separation layer so as to have the same height as the first layer conductor, a step of forming a first layer conductor on the insulating layer and the gap portion by metal plating, and a step of using a metal paste in the gap portion. The step of printing and forming the resistance electrode so that there is no step with the undercoat, and the resistor is formed on the upper surface of the resistance electrode and the upper surface of the undercoat so as to have the same height as the first-layer conductor on the insulating layer. And a step of performing.

Further, the wiring board with a built-in resistor according to the present invention has the first layer conductor separately provided so as to have the gap on the base substrate, the side surface on the gap side of the first layer conductor, and the upper surface. A resistance electrode formed continuously in the, and an undercoat using an insulating material formed in the gap at the same height as the resistance electrode,
It comprises a resistor formed on a flat surface that is continuous with the upper surface of the resistance electrode and the upper surface of the undercoat.

As a method of manufacturing this wiring board with built-in resistors,
A step of providing the first layer conductors so as to face each other so as to have a gap on the base substrate, and a step of continuously forming a resistance electrode on the side surface of the first layer conductor on the gap side and the upper surface. When,
A step of applying an insulating material thicker than the resistance electrode so as to fill at least the gap; a step of polishing the insulation material to expose the resistance electrode to form a flat surface; a resistance electrode upper surface and an insulation material And a step of forming a resistor on the upper surface.

These wiring boards with built-in resistors are wiring boards in which a plurality of wirings with built-in resistors are arranged adjacent to each other on the same wiring board with an insulating separation layer interposed therebetween. The same plane is a flat surface.

Furthermore, these wiring boards with built-in resistors have at least a base substrate, a first-layer conductor, and a resistor, and an overcoat made of an insulating material and having a flat surface. The method of manufacturing this wiring board with built-in resistors includes the steps of forming the resistor in the above manufacturing method, then covering the base substrate, the first-layer conductor, and the resistor with an overcoat made of an insulating material, and polishing the surface. And a flattening step.

[0019]

With the above construction, the resistor printing portion becomes flat. As a result, the printability of the resistor is improved, and sagging and bleeding are less likely to occur. Since there is no step between the resistance electrode and the resistor, stress concentration on the resistor is eliminated, and there is no fear that the resistance value will change. Although the first layer conductor is not flat, since metal plating is used, no crack occurs.

Further, since the resistor can be formed at the same height as the first layer conductor, the insulating layer on the resistor is also flat. The printability when forming the second-layer conductor on the insulating layer with a metal paste such as copper is also improved. As a result, the problem that sagging, bleeding, and the like are likely to occur is solved, and high-density wiring of the second-layer conductor is possible. This is also the case when the second layer conductor is formed on the insulating layer by metal plating such as copper. Further, the present invention has a feature that it can be realized by a conventional material without requiring a special material.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Embodiments 1 to 5 describe the first object of the present invention, that is, an example of realizing a wiring board with a built-in resistor for flattening the printed surface of the resistor. In addition, Examples 6 and 7 have a second object of the present invention, namely, not only to flatten the resistor printed surface but also to print the second layer conductor, resistor, etc. when forming an upper layer. Examples of realizing a wiring board with a built-in resistor for flattening are described below. In addition, Examples 8 and 9 describe applications of the wiring board with a built-in resistor of the present invention.

<Embodiment 1> (1) Structure FIG. 9 is a sectional view of an essential part showing an example of a wiring board with a built-in resistor. In this figure, 1 is a base substrate (hereinafter referred to as a base substrate), 2a is an insulating layer, 4 is an undercoat also made of an insulator, 5 is a first layer conductor which is wiring, and 6 is a first layer. A resistance electrode (a silver electrode in this example) that connects the conductor 5 and the resistor 7 is the same as the undercoat 4
An overcoat made of an insulating material, and 9 is a second layer conductor which is an upper layer conductor. As you can see from this figure, resistor 7
Is arranged in a region where the undercoat 4 and the silver electrode 6 which are bases are flat and form the same plane.

(2) Manufacturing Flow FIG. 3 is a process chart showing the manufacturing flow, and the process sequence will be described below. Step (a): An insulating material made of a photosensitive resin is applied onto the base substrate 1 made of glass epoxy. Next, exposure is performed through a mask on which a predetermined circuit pattern is formed.
Further, it is developed and dissolved to form a pattern having the same film thickness (about 20 μm) as that of the first-layer conductor 5 to be formed later, and the insulating layer 2a facing each other. Step (b): A well-known copper plating catalyst 3 such as palladium is provided on the base substrate 1 and the insulating layer 2a.

Step (c): An undercoat 4 made of an insulating material is formed, for example, by screen printing between the insulating layers 2a facing each other. At this time, undercoat 4
Is a film thickness (about 40 μm) obtained by adding the film thicknesses of the insulating layer 2a and the first-layer conductors 5 to be formed later. Further, the insulating layer 2a and the insulating layer 2a are formed so as to have a gap portion 11 which will be a formation region of the silver electrode 6 in a later step. Step (d): Chemical copper plating is selectively performed on the insulating layer 2a and the gap portion 11 to form the first-layer conductor 5 having the same film thickness (about 20 μm) as the insulating layer 2a. Step (e): A silver electrode for resistance 6 (about 20 μm) is printed and formed in the gap 11 using a metal paste so that there is no step with the undercoat 4. As a result, the flat resistor printed surface 13 is formed. Step (f): The resistor 7 (2
0 μm) is formed by printing.

(3) Effect As can be seen from the step of FIG. 3 (e) and the above description, the base printing surface 13 of the resistor 7 is flat. As a result, even if the resistor 7 is printed, sagging and blurring do not occur. Also,
Since there is no step, there is no problem of stress concentration. Further, if the insulating layer 2a is formed also in the non-wiring portion, the step between the portion where the resistor 7 is formed and the portion where it is not formed corresponds to two steps of the resistor 7 and the first layer conductor 5.
The number of steps is smaller than that in the conventional example having three steps as shown in FIG. Therefore, the overcoat 8
Even when applying and forming an upper layer on it,
The surface of the overcoat 8 becomes flatter. As a result,
There is also an effect that the printability of the second layer conductor 9 shown in FIG. 9 is increased.

<Embodiment 2> (1) Structure FIG. 10 is a sectional view of an essential part showing an example of a wiring board with a built-in resistor. 2b in this figure is an insulating layer like 2a. As can be seen from this figure, the point different from FIG. 9 illustrated in Example 1 is that the thickness of the undercoat 4 is reduced and that portion is supplemented by the insulating layer 2b. The resistor 7 is arranged in a region where the undercoat 4 and the silver electrode 6 are flat and form the same plane as in the structure of the first embodiment.

(2) Manufacturing Flow FIG. 4 is a process chart showing the manufacturing flow, and the process sequence will be described below. Step (a): An insulating material made of a photosensitive resin is applied onto the base substrate 1 made of glass epoxy. Next, exposure is performed through a mask on which a predetermined circuit pattern is formed.
Further developed and dissolved, the insulating layers 2 facing each other and having the same film thickness (about 20 μm) as the first layer conductor 5 formed later.
At the same time, a pattern is formed between a and the insulating layer 2a, which is between the a and the insulating layer 2a, and the insulating layer 2b which forms the gap portion 11 which becomes the formation region of the resistance silver electrode 6 in a later step. Step (b): A well-known copper plating catalyst 3 such as palladium is applied onto the base substrate 1 and the insulating layers 2a and 2b.

Step (c): The insulating layer 2 is formed on the insulating layer 2b.
Undercoat 4 (20μ with the same thickness as a and 2b)
m) is formed by screen printing, for example. The copper plating catalyst does not work in the portion where the undercoat 4 is formed. Step (d): Selectively perform chemical copper plating on the insulating layer 2a and on the gap portion 11 so as to have the same height as the surface of the undercoat 4 (in this case, the same film as the insulating layers 2a and 2b). A first layer conductor 5 (having a thickness of about 20 μm) is formed. Step (e): The silver electrode for resistance 6 (20 μm) so that the gap 11 has no step with the undercoat 4 and the first-layer conductor 5.
Is formed by printing using a metal paste. As a result, the flat resistor printed surface 13 is formed. Step (f): The resistor 7 (2
0 μm) is formed by printing.

(3) Effect As can be seen from the process shown in FIG. 4E and the above description, the base printing surface 13 of the resistor 7 is flat. As a result, even if the resistor 7 is printed, sagging and blurring do not occur. Also,
Since there is no step, there is no problem of stress concentration. Further, if the insulating layer 2a is formed also in the non-wiring portion, the step between the portion where the resistor 7 is formed and the portion where it is not formed corresponds to two steps of the resistor 7 and the first layer conductor 5.
The number of steps is smaller than that in the conventional example having three steps as shown in FIG. Therefore, the overcoat 8
Even when applying and forming an upper layer on it,
The surface of the overcoat 8 becomes flatter. As a result,
There is also an effect that the printability of the second-layer conductor 9 shown in FIG. 10 is increased.

<Embodiment 3> (1) Structure FIG. 11 is a sectional view of an essential part showing an example of a wiring board with a built-in resistor. As can be seen from this figure, the point different from FIGS. 9 and 10 illustrated in Examples 1 and 2 is that the silver electrode for resistance 6 is directly formed on the first layer conductor without forming the undercoat 4. is there. The resistor 7 is arranged at a position where the insulating layer 2a and the silver electrode 6 are flat and have the same height.

(2) Manufacturing Flow FIG. 5 is a process chart showing the manufacturing flow, and the process sequence will be described below. Step (a): The copper foil 12 is formed on the base substrate 1 made of glass epoxy. Step (b): The copper foil 12 is etched using a mask on which a predetermined circuit pattern is formed to form a pattern of the first layer conductor 5. Step (c): The resistance silver electrode 6 is formed on the first-layer conductor 5 by using a metal paste, for example, by screen printing.

Step (d): Printing on the base substrate 1, the first-layer conductor 5, and the silver electrode for resistance 6 with a thickness not less than the total thickness of the first-layer conductor 5 and the silver electrode for resistance 6 Alternatively, the insulating layer 2a is provided by coating. Step (e): polishing is performed so that the insulating layer 2a has a uniform height and only the resistance silver electrode 6 is exposed from the insulating layer 2a. As a result, a flat resistor printing surface 13 including the upper surface of the resistor silver electrode 6 and the upper surface of the insulating layer 2a is formed. Step (f): The resistor 7 (2
0 μm) is formed by printing.

(3) Effect As can be seen from the step of FIG. 5E and the above description, the printed surface 13 of the resistor 7 is flat. As a result, even if the resistor 7 is printed, sagging and blurring do not occur. Further, since there is no stepped portion, the problem of stress concentration does not occur. Further, if the insulating layer 2a is formed also in the non-wiring portion, the step between the portion where the resistor 7 is formed and the portion where it is not formed corresponds to one step of the resistor 7. The number of steps is smaller than that in the conventional example having three steps as shown in FIG. Therefore, even when the overcoat 8 is applied and an upper layer is further formed thereon, the surface of the overcoat 8 becomes flatter. As a result, there is an effect that the printability of the second layer conductor 9 is increased.

<Embodiment 4> (1) Structure FIG. 7 is a sectional view of an essential part showing an example of a wiring board with a built-in resistor. As can be seen from this figure, the resistor 7 is arranged where the undercoat 4 and the silver electrode 6 are flat and have the same height. Further, a feature of this embodiment is that the height after formation is the same as that of the first-layer conductor on the insulating layer a, which is different from the above-described embodiments.

(2) Manufacturing Flow FIG. 1 is a process chart showing the manufacturing flow, and the process sequence will be described below. Step (a): An insulating material made of a photosensitive resin is applied onto the base substrate 1 made of glass epoxy. Next, the film is exposed through a mask on which a predetermined circuit pattern is formed, further developed and dissolved, and the film thickness (about 40 μm) is obtained by adding the first-layer conductor 5 and the silver electrode 6 for resistance formed later. And a pattern made of the insulating layers 2a facing each other is formed. Step (b): A copper plating catalyst 3 such as palladium is applied on the base substrate and the insulating layer 2a. Step (c): An undercoat 4 made of an insulating material is formed, for example, by screen printing between the insulating layers 2a facing each other. At this time, the undercoat 4 has a film thickness (about 40 μm) obtained by adding the film thicknesses of the insulating layer 2a and the first-layer conductors 5 to be formed later. At this time, the undercoat print pattern is formed so as to have a gap 11 between the insulating layer 2a and the insulating layer 2a, which will be a region for forming the silver electrode 6 in a later step.

Step (d): Using the above-mentioned copper plating catalyst 3, the first layer conductor 5 (about 20 μm) is selectively formed in the insulating layer 2a and the gap portion 11 by chemical copper plating. Step (e): A silver electrode for resistance 6 (about 20 μm) is printed and formed in the gap 11 using a metal paste so that there is no step with the undercoat 4. As a result, the flat resistor printed surface 13 is formed. Step (f): The resistor 7 is printed on the resistor printing surface 13. At this time, the thickness of the resistor 7 is adjusted so that the thickness of the resistor 7 and the undercoat 4 is equal to the thickness of the first conductor 5 and the insulating layer 2a. Is about 20 μm.

(3) Effect As can be seen from the step of FIG. 1 (e) and the above description, the printed surface 13 of the resistor 7 is flat. As a result, even if the resistor 7 is printed, sagging and blurring do not occur. Further, since there is no stepped portion, the problem of stress concentration does not occur. Further, if the insulating layer 2a is formed also in the non-wiring part, the step difference between the resistor 7 and the portion where the first layer conductor 5 is formed on the insulating layer 2a and the portion other than the resistor 7 are It is one stage of the first layer conductor 5 on the same plane. Compared with the case of having three steps in the conventional example shown in FIG. 6,
There are fewer steps. Therefore, even when the overcoat 8 is applied to form an upper layer, the surface of the overcoat 8 becomes flatter. As a result, the second-layer conductor 9
It also has the effect of increasing the printability of.

<Embodiment 5> (1) Structure FIG. 8 is a sectional view of an essential part showing an example of a wiring board with a built-in resistor. Reference numeral 10 in this figure is a thin film resistance electrode formed by metal plating. The feature of this embodiment is that the thin film electrode for resistance is used instead of the silver electrode 6 of FIG. As can be seen from this figure, the resistor 7 is arranged where the resistor thin film electrode 10 on the first layer conductor 5 and the undercoat 4 are flat and at the same height. Furthermore, this embodiment is similar to the fourth embodiment in that the height after the resistor 7 is formed is the same as that of the first layer conductor on the insulating layer 2a.

(2) Manufacturing Flow FIG. 2 is a process chart showing the manufacturing flow, and the process sequence will be described below. Step (a): An insulating material made of a photosensitive resin is applied onto the base substrate 1 made of glass epoxy. Next, it is exposed through a mask on which a predetermined circuit pattern is formed, further developed and dissolved, and has the same film thickness (about 20 μm) as the first-layer conductor 5 to be formed later, and the insulating layers are opposed to each other. Form the layer 2a. Step (b): A well-known copper plating catalyst 3 such as palladium is provided on the base substrate 1 and the insulating layer 2a. Step (c): The insulating layer 2a is provided between the insulating layers 2a facing each other.
Undercoat 4 (about 20 μm) with the same thickness as
Are formed by screen printing, for example. Undercoat 4
The copper plating catalyst does not work in the formation part of. As a print pattern at this time, a gap portion 11 to be a region for forming the resistance silver electrode 6 in a later step is formed between the insulating layer 2a and the undercoat 4.

Step (d): on the insulating layer 2a and the gap 11
Then, the first-layer conductor 5 (about 20 μm) having the same thickness as the undercoat 4 is selectively formed by copper plating. Step (e): The resistance thin film electrode 10 is formed on the entire first layer conductor 5 as an anti-oxidation film by gold plating or the like. Gold plating
Since the thickness is as thin as about 3 μm, the resistor printing surface 13 becomes flat. Step (f): The resistor 7 is printed on the resistor printing surface 13. At this time, the resistance is adjusted so that the total thickness of the resistor 7 and the undercoat 4 is equal to the total thickness of the first layer conductor 5 and the gold plating 10. The thickness of the body 7 is about 20 μm.

(3) Effect As can be seen from the step of FIG. 2 (e) and the above description, the base printing surface 13 of the resistor 7 is flat. As a result, even if the resistor 7 is printed, sagging and blurring do not occur. Also,
Since there is no step, there is no problem of stress concentration. Further, if the insulating layer 2a is formed also in the non-wiring part, the resistor 7 and the first-layer conductor 5 are formed on the insulating layer 2a.
In the portion where is formed, the step is one step of the resistor 7 and the first layer conductor 5 as compared with the portion where it is not formed. The number of steps is smaller than that in the conventional example having three steps as shown in FIG. Therefore, even when the overcoat 8 is applied to form an upper layer, the surface of the overcoat 8 becomes flatter. As a result, the printability of the second-layer conductor 9 shown in FIG. 8 is also increased.

As described above, in any of the first to fifth embodiments, the printing surface 13 of the resistor 7 is flat, which is the first object of the present invention, namely, printing of the resistor. We have realized a wiring board with a built-in resistor that flattens the surface.
Therefore, unlike the conventional example, stress is not concentrated on the stepped portion of the resistor 7. Even when the overcoat 8 is applied and an upper layer is further formed thereon, the surface of the overcoat 8 becomes flatter. As a result, there is also an effect that the printability of the second layer conductor is increased.

<Embodiment 6> (1) Structure FIG. 12 is a perspective view showing a main part of a wiring board with a built-in resistor, showing that three wiring patterns with built-in resistors are arranged side by side. In this figure, (a) shows a state before forming the insulating separation layer, and (b) shows a state after forming the insulating separation layer. Reference numeral 14 in this figure is a separation layer filling the space between the three wiring patterns. The feature of this embodiment is (b)
As shown in, even after the wiring pattern with built-in resistors is formed, it is flat over the entire surface of the wiring board. (C) is a figure which formed the orthogonal wiring pattern on (b).

(2) Manufacturing Flow The manufacturing flow will be described in the order of steps with reference to FIG. In addition,
In this embodiment, the insulating layer 2a is formed only on the portion on which the first-layer conductor is formed. Step (a): The resistor built-in wiring pattern is formed by the same steps as those described in the fourth and fifth embodiments. Step (b): For example, by screen printing, the separation layer 14 made of an insulating material is selectively formed in a portion where the wiring pattern is not formed. The thickness of the separation layer 14 is the same as the height of the upper surface of the surface on which the adjacent wiring pattern is formed. Step (c): An upper layer is formed in the same manner as in step (a).

(3) Effect As can be seen from the process of FIG. 12B and the above description, not only the resistor 7 is printed flat, but also the wiring board including the conductor 5, the resistor 7, and the separation layer 14. The entire surface has the same height. Therefore, even when forming an upper layer, by applying the overcoat 8 to a uniform thickness,
The layer can be formed exactly as in the case of forming the first layer. By repeating this, the resistor in the upper layer,
The printability of the first-layer conductor is good, that is, it is easy to form a multilayer wiring board having a built-in resistor capable of high-density wiring.

<Embodiment 7> (1) Structure FIG. 13 is a sectional view of an essential part showing an example of a wiring board with a built-in resistor. This figure shows a case where an overcoat 8 is applied on the resistor wiring pattern formed in Example 4, and is a cross-sectional view of the undercoat 4 at a right angle to the wiring direction.
This figure shows that two wires are lined up. Also in this embodiment, the insulating layer 2a is formed only in the portion on which the first-layer conductor is formed. As can be seen from this figure, the entire surface is not flat when the resistor 7 is printed. However, the feature of this embodiment is that the height of the wiring board is made flat over the entire surface when the overcoat 8 is formed. This improves the printability of the upper layer.

(2) Manufacturing Flow The manufacturing flow will be described in the order of steps with reference to FIG. Since the steps up to the step of printing the resistor are the same as the step (e) of the fourth embodiment, description thereof will be omitted. Step (f): The resistor 7 is formed. Step (g): The overcoat 8 is applied to the entire surface so as to have a height equal to or higher than that of the resistor 7. Step (h): The entire surface is polished to be flat. At this time,
The resistor 7 and the first-layer conductor 5 are prevented from being exposed.

(3) Effect As can be seen from the step of FIG. 13 (h) and the above description, the surface of the overcoat 8 is flat. Therefore,
Printability increases when a resistor and a conductor are formed by printing on the second layer. When printing the same resistor on a multi-layer substrate having three or more layers, the same process as described above may be repeated after forming the overcoat 8 in FIG. For example,
It is also possible to use the wiring board with a built-in resistor in a multi-layer board of several tens of layers used in a large computer.

<Embodiment 8> (1) Structure In the above embodiments, a single-sided wiring board has been described for simplification of description, but the present invention can be applied to a double-sided wiring board. FIG. 14 is a structural diagram in which Example 4 of the present invention is applied to a double-sided wiring board. Also in this example,
As in the other embodiments, it is possible to provide a wiring board with a built-in resistor that enables high-density wiring and high reliability. Note that, although FIG. 14 is drawn vertically symmetrically, of course, the formation position of the resistor is not limited to this, and the structures of two different embodiments may be combined.

<Embodiment 9> FIG. 15 is a diagram showing an LSI mounted on a wiring board with a built-in resistor according to the present invention. 15 in this figure is L
The SI package, 16 is an LSI pin, and the pin 16 is fixed to the second layer conductor 9 by soldering. L
The narrow pitch and multiple pins of SI pins 16 are becoming more and more advanced. There is an increasing demand for high-density wiring on the LSI mounting surface. Conventionally, the surface is not flat, so the printability is poor, and even if the LSI cannot be mounted as a result,
By applying Example 6 which can make the surface flat,
High-density wiring on the surface of the wiring board is possible. Therefore, it is possible to deal with this narrow pitch, multi-pin LSI. As a result,
A small-sized device can be realized by using a narrow-pitch multi-pin LSI.

<Other Embodiments> In addition, in the embodiments of the present invention, a specific substance is described as an example. However, this is an example, and other substances having similar properties may be used. For example, the base substrate is not limited to the glass epoxy substrate, but may be a ceramic substrate or a metal insulating material. Further, silver used as an electrode, gold and copper used as a conductor are not limited to these, and a printable metal paste or a plateable metal may be used.

[0052]

As described above, according to the present invention, the intended purpose can be achieved. That is, since the printed surface of the resistor can be made flat, (1) sagging at the time of printing is eliminated, so that the resistor has a uniform thickness. It is possible to reduce variation in resistance value due to partial thinning. (2) Since blurring during printing is eliminated, high density printing (wiring) of the inner layer is possible. (3) Since the printed resistor has no step, stress concentration does not occur. Improves reliability when heat shrinks and handles wiring boards.

Further, since the printability can be improved in each layer of the multilayer substrate having three or more layers or the surface of the wiring board, (4) high-density wiring can be performed on the upper layer or the surface. The board can be miniaturized, and especially on the surface, there are features such as an LSI package having a narrow pin pitch, and mounting of small parts. Furthermore, the surface of each layer can be made flat over the entire surface. (5) The printability is further improved, and high density wiring of each layer of the multilayer substrate is possible.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram of a fourth embodiment of the present invention.

FIG. 2 is a manufacturing process diagram of a fifth embodiment of the present invention.

FIG. 3 is a manufacturing process diagram of the first embodiment of the present invention.

FIG. 4 is a manufacturing process diagram of Embodiment 2 of the present invention.

FIG. 5 is a manufacturing process diagram of Embodiment 3 of the present invention.

FIG. 6 is a sectional view of a main part of a conventional wiring board with built-in resistors.

FIG. 7 is a sectional view showing the structure of Example 4 of the present invention.

FIG. 8 is a sectional view showing the structure of Example 5 of the present invention.

FIG. 9 is a cross-sectional view showing the structure of Example 1 of the present invention.

FIG. 10 is a cross-sectional view showing the structure of Example 2 of the present invention.

FIG. 11 is a sectional view showing the structure of Example 3 of the present invention.

FIG. 12 is a perspective view showing the structure of Example 6 of the present invention.

FIG. 13 is a manufacturing process diagram of Example 7 of the present invention.

FIG. 14 is a sectional view showing an example of the structure of Example 8 of the present invention.

FIG. 15 is a perspective view showing an example of the structure of Example 9 of the present invention.

[Explanation of symbols]

1 ... Base substrate, 2a ... Insulating layer, 2b ...
Insulating layer, 3 ... Copper plating catalyst, 4 ... Undercoat,
5 ... First layer conductor, 6 ... Silver electrode, 7 ... Resistor, 8 ... Overcoat, 9 ... Second layer conductor,
10 ... Resistor thin film electrode, 11 ... Gap, 12 ... Copper foil, 13 ... Resistor printed surface.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Terutake Kato 216 Totsuka-cho, Totsuka-ku, Yokohama City, Kanagawa Prefecture Hitachi Ltd., Information & Communication Division (72) Inventor Satoshi Hashimoto 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi, Ltd. Information & Communication Division

Claims (15)

[Claims] 1. A base substrate, an insulating layer provided separately on the base substrate, an undercoat formed by using an insulating material between these insulating layers, and a resistor provided at least on the undercoat. A wiring board with built-in resistance, comprising: an electrode connected to the resistance body, wherein the resistance body is provided in a region where a base is flat. 2. A base substrate, an insulating layer provided separately on the base substrate, and an insulating material having the same film thickness as the insulating layer, which is separated by a gap between the insulating layers. An undercoat formed by using, a conductor continuously formed on the insulating layer and the gap with a thickness smaller than that of the insulating layer by using metal plating, and an undercoat by using a metal paste in the gap. Built-in resistor that has a resistance electrode formed at the same height and a resistor formed at the same height as the conductor on the insulating layer on a continuous flat surface of the resistance electrode upper surface and the undercoat upper surface Wiring board. 3. A base substrate, an insulating layer provided separately on the base substrate, and an insulating material having the same film thickness as the insulating layer between the insulating layers and separated from each other by a gap. Undercoat formed by using, a conductor continuously formed on the insulating layer and the gap with the same film thickness as the undercoat by metal plating, and a resistor formed by metal plating on the upper surface of the conductor. And a resistor formed on the undercoat and on the same plane as the undercoat on a continuous flat surface on the resistor thin film electrode region at substantially the same height as the conductor on the insulating layer. Wiring board with built-in resistor. 4. A base substrate, an insulating layer provided separately on the base substrate, and an insulating material having a thickness larger than that of the insulating layer and separated from each other by a gap between the insulating layers. An undercoat formed by using, a conductor formed continuously on the insulating layer and the gap portion by using metal plating so that the height on the insulating layer is the same as the undercoat,
In the gap plated with metal, a resistance electrode formed with a metal paste at the same height as the undercoat, and a resistor formed on a continuous flat surface of the resistance electrode upper surface and the undercoat upper surface are provided. A wiring board with a built-in resistor. 5. A base substrate, a first-layer conductor provided separately on the base substrate so as to have a gap, and a resistor continuously formed on a side face and an upper face of the first-layer conductor on the gap side. Electrode, an undercoat having the same height as the resistance electrode and formed of an insulating material in the gap, and a resistor formed on a continuous flat surface of the resistance electrode upper surface and the undercoat upper surface. A wiring board with a built-in resistor. 6. The wiring board according to claim 1, wherein a plurality of wirings with built-in resistors are adjacently arranged on the same wiring board with an insulating separation layer interposed therebetween, and a plurality of wirings are arranged. A wiring board with a built-in resistor in which the same plane of the wiring board is a flat surface. 7. The resistor built-in wiring board according to claim 1, further comprising an overcoat made of an insulating material, the overcoat having a flat surface that covers at least the base substrate, the first-layer conductor, and the resistor. 8. An electronic device in which electronic parts are mounted and connected on a wiring board with a built-in resistor, wherein the wiring board with a built-in resistance comprises the wiring board with a built-in resistance according to any one of claims 1 to 7. 9. A method of manufacturing a wiring board with a built-in resistor, comprising forming a resistor by printing on a base substrate.
At least a step of separately providing an insulating layer so as to face the resistor formation region, a step of applying a metal plating catalyst on the base substrate and the insulating layer, and a gap between the opposing insulating layers, A step of forming an undercoat having the same thickness as the insulating layer and using an insulating material, a step of forming a first-layer conductor by metal plating on the insulating layer and in the gap, and a metal paste in the gap. The step of printing and forming the resistance electrode so that there is no step difference from the undercoat using, and the same level as the first-layer conductor on the insulating layer on the continuous flat surface of the resistance electrode upper surface and the undercoat upper surface. And a step of forming a resistor so that 10. A method of manufacturing a wiring board with a built-in resistor in which a resistor is formed by printing on a base substrate, and a step of separately providing an insulating layer on the base substrate so as to face at least a resistor forming region. A step of applying a metal plating catalyst on the base substrate and the insulating layer and forming an undercoat using an insulating material having a gap between the opposing insulating layers and having the same thickness as the insulating layer And the process of
The step of forming the first layer conductor by metal plating on the insulating layer and the gap so that the height formed on the base substrate is the same as the undercoat, and the metal plating on the upper surface of the first layer conductor. A step of forming a thin film resistance electrode, and a first layer conductor on the insulating layer on the undercoat on the base substrate, and on a continuous flat surface on the thin film resistance electrode region on the same plane as the undercoat. A method of manufacturing a wiring board with a built-in resistor, comprising the step of selectively forming resistors so as to have the same height. 11. A method of manufacturing a wiring board with a built-in resistor in which a resistor is formed by printing on a base substrate, and a step of separately providing an insulating layer on the base substrate so as to face at least a resistor formation region. A step of applying a metal plating catalyst on the base substrate and the insulating layer, and an undercoat using an insulating material having a gap between the opposing insulating layers and having a thickness larger than that of the insulating layer. The step of forming, the step of forming the first-layer conductor by metal plating on the insulating layer and the gap so that the thin film on the insulating layer has the same height as the undercoat, and using the metal paste in the gap Built-in resistor including a step of forming a resistor electrode by printing so that there is no step between the undercoat and the resistor, and a step of forming a resistor on a continuous flat surface between the resistor electrode upper surface and the undercoat upper surface. Distribution Method of manufacturing the plate. 12. A method of manufacturing a wiring board with a built-in resistor, comprising forming a resistor by printing on a base substrate, wherein a first insulating layer is separated on the base substrate so as to face at least a resistor forming region. A step of forming a second insulating layer apart from the first insulating layer in the resistor forming region, and a step of applying a metal plating catalyst on the base substrate and the insulating layer; A step of forming an undercoat on the insulating layer so that the height of the first layer conductor is substantially the same as that of a first layer conductor formed later using an insulating material, and the insulating layer is formed by metal plating on the insulating layer and the gap. A step of forming a first-layer conductor so that the upper thin film is at the same height as the undercoat, and a step of printing and forming a resistance electrode so that there is no step with the undercoat by using a metal paste in the gap , The upper surface of the resistor electrode and A continuous flat surface on the Dakoto top method of manufacturing a resistance wiring board with a built-made and a step of forming a resistor. 13. A method of manufacturing a wiring board with a built-in resistor in which a resistor is formed by printing on a base substrate, a step of providing first-layer conductors facing each other so as to have a gap on the base substrate, A step of continuously forming a resistance electrode on the side surface on the gap side of the first layer conductor and the upper surface; and a step of applying an insulating material so as to fill at least the gap and higher than the resistance electrode. The method includes a step of polishing the insulating material to expose the resistance electrode and forming a flat surface, and a step of forming a resistor on the continuous flat surface of the resistance electrode upper surface and the insulating material upper surface. Of manufacturing a wiring board with a built-in resistor. 14. After the resistor is formed, at least the base substrate, the first-layer conductor, and the resistor are covered with an overcoat made of an insulating material, and the surface of the overcoat is polished to be flattened. 14. The method for manufacturing a wiring board with built-in resistors according to claim 9, comprising: 15. A method of manufacturing a wiring board with a built-in resistor, wherein a plurality of wirings with a built-in resistance are arranged adjacent to each other with an insulation separation layer on a base substrate, and a wiring board including the insulation separation layer has a flat surface on the same plane. A step of separately providing an insulating layer on the wiring portion on the base substrate so as to face at least the resistor forming region; a step of applying a metal plating catalyst on the base substrate and the insulating layer; A step of forming an undercoat using an insulating material having a gap and having the same thickness as the insulating layer between the layers, and a step of forming a first-layer conductor on the insulating layer and on the gap by metal plating When,
A step of printing and forming a resistance electrode in the gap portion using a metal paste so that there is no step difference from the undercoat,
On the continuous flat surface of the resistance electrode upper surface and the undercoat upper surface, the step of forming a resistor so as to be the same height as the first layer conductor on the insulating layer, and the non-wiring portion on the base substrate, A method of manufacturing a wiring board with a built-in resistor, comprising the step of forming an insulating separation layer having the same height as the resistor and the first-layer conductor.