JP4352311B2 - Thick film circuit board - Google Patents

Description

  The present invention relates to a thick film circuit board, and more particularly to a thick film circuit board in which a conductor layer does not peel when an element is attached to the conductor layer.

  Conventionally, electrical elements are assembled on thick film circuit boards. The thick film circuit board has an insulating base material and a conductor layer formed on the surface of the base material. A conductor layer that conducts electricity in a thick film circuit board is required to satisfy characteristics such as adhesion to a base material, soldering strength, and matching with a resistor.

  In order to ensure sufficient soldering strength, it is necessary not only to improve the adhesion between the conductor layer and the substrate, but also to densify the conductor layer itself. In particular, it is known that the density of the conductor layer greatly affects the solder diffusion when left at high temperature. Specifically, when the conductor layer is porous, the diffusion layer produced by the diffusion of solder in soldering becomes thick, and the adhesion strength between the conductor layer and the substrate is greatly reduced due to stress produced by the diffusion layer.

  In addition, if the conductor layer is made dense (improvement in density), the stress acting from the periphery of the conductor layer to the center increases, causing the problem that the periphery of the conductor layer peels off (floats) from the substrate. It was. When the peripheral portion of the conductor layer is peeled off from the substrate, the area of the contact portion between the conductor layer and the base material is reduced, and the soldering strength of the conductor layer is reduced.

Peeling of the peripheral portion of the conductor layer is likely to occur in a conductor layer obtained by baking the copper conductive paste described in Patent Document 1 at a low temperature. Specifically, since the copper conductive paste is fired at a low temperature to form a conductor layer, the metal powder in the paste is pulverized. Although the sinterability of the paste is improved by pulverizing the metal powder, at the same time, shrinkage (volume reduction) during sintering is likely to occur. Due to this shrinkage, stress is applied to the peripheral portion of the conductor layer in the direction of the center of the conductor layer. Due to this residual stress, the peripheral portion of the conductor layer is likely to be peeled off (lifted up) from the substrate.
Japanese Patent Laid-Open No. 11-329066

  This invention is made | formed in view of the said actual condition, and makes it a subject to provide the thick film circuit board from which the peripheral part of a conductor layer does not peel from a base material.

  In order to solve the above-mentioned problems, the present inventors have studied the thick film circuit board, and as a result, have reached the present invention.

The thick film circuit board of the present invention has an insulating base material, a glass layer made of glass formed on the surface of the base material, and a conductive layer that conducts electricity formed on the glass layer , The conductor layer is a metal powder capable of forming a conductor layer after firing, and a powder having an average particle size of 0.1 to 10 μm is used, and a conductor paste to which at least one of Mn, Ti, and Ge is added is fired. Thus, the glass layer is at least at the periphery of the conductor layer, and is formed to have a size protruding from the conductor layer.

In the thick film circuit board of the present invention, the glass layer fixes the conductor layer on the base material. Furthermore, the conductive layer does not peel from the glass layer in order to prevent the peripheral portion from being lifted up by bonding the conductive layer and the glass layer previously laid on the conductive layer before shrinking during firing. As a result, the thick film circuit board of the present invention can ensure sufficient soldering strength because peeling of the peripheral portion of the conductor layer from the base material does not occur.
The thick film circuit board of the present invention has an insulating base material, a glass layer made of glass formed on the surface of the base material, and a conductive layer that conducts electricity formed on the glass layer, The glass layer is formed only in the peripheral portion of the conductor layer and has a size protruding from the conductor layer.

The thick film circuit board of the present invention has a glass layer to suppress peeling of the conductor layer from the base material. For this reason, in the thick film circuit board of the present invention, peeling from the base material at the peripheral portion of the conductor layer does not occur, so that sufficient soldering strength is ensured.

The thick film circuit board of this invention has a base material, a glass layer, and a conductor layer.

  As the base material, a base material used in a conventionally known circuit board can be used. As the substrate, for example, an alumina ceramic substrate in which a ceramic such as alumina is formed in a plate shape can be used.

  The glass layer is formed on the substrate surface. The glass forming the glass layer is not particularly limited as long as it can be formed on the surface of the substrate and can fix the conductor layer. For example, ZnO-based or PbO-based glass can be used.

  The conductor layer is formed on the glass layer. That is, the conductive layer is formed on the glass layer, so that the glass layer fixes the conductive layer on the substrate. By fixing the conductor layer to the glass layer, peeling of the peripheral portion of the conductor layer is suppressed.

  The conductor layer is a member through which electricity flows in the thick film circuit board. The conductor layer is formed on the substrate according to a predetermined circuit pattern.

  The glass layer is preferably formed at least on the part on which the component is mounted on the conductor layer. Since the glass layer is formed at least on the part (joint part) where the component (external element) is mounted, when the external element is soldered to the joint part, stress is applied to the peripheral part of the conductor layer due to the diffusion of the solder. However, the conductor layer does not peel off due to the effect of the glass layer. In other words, the glass layer is preferably formed under the conductor layer that applies particularly strong stress to the peripheral edge.

  The conductor layer is preferably fired. In the conductor layer that has been fired, the stress generated by shrinkage during firing remains. This residual stress is a force toward the central portion (portion where the conductor layer is thick) at the peripheral portion. In a conventional circuit board having no glass layer, the conductor layer is not sufficiently thick at the peripheral edge, and therefore, peeling from the base material is likely to occur. On the other hand, when the glass layer is provided like the thick film circuit board of the present invention, the conductor layer and the glass layer are joined before the conductor layer shrinks at the time of firing, thereby preventing the peeling of the conductor layer at the time of firing. . That is, in the thick film circuit board of the present invention, the peripheral portion of the conductor layer does not peel from the base material even in the baked conductor layer in which the peripheral portion is easily peeled.

  The conductor layer is preferably fired after the glass layer is formed. That is, instead of forming the glass layer and the conductor layer at the same time, by forming the conductor layer after the formation of the glass layer, it is possible to suppress the elements forming the glass layer and the conductor layer from diffusing into the other during firing. .

  The softening point of the glass forming the glass layer is preferably lower than the firing temperature of the conductor layer. When the glass softening point is lower than the firing temperature of the conductor layer, the glass layer softens during firing of the conductor layer, and the shrinkage of the conductor layer can be alleviated.

  The conductor layer is preferably made of a Cu-based conductor fired at 750 ° C. or lower. Since the Cu-based conductor fired at 750 ° C. or less has a large shrinkage during firing, peeling on the peripheral edge can be suppressed by firing on the glass layer. Moreover, even if the thick film circuit board of the present invention is densified in order to obtain sufficient soldering strength, the peripheral portion of the conductor layer does not peel off.

  Firing of the Cu-based conductor is performed in an inert gas atmosphere. Here, the inert gas atmosphere may be any gas that does not react with the Cu-based conductor, and examples thereof include nitrogen, helium, neon, argon, and the like. It is preferable.

  The Cu-based conductor forming the conductor layer can be a conventionally known Cu-based conductor as long as it is a conductor fired at a temperature of 750 ° C. or lower. Preferably, the conductor is fired at 600 to 700 ° C. Examples of the Cu-based conductor include a sintered body of low-temperature copper conductor paste containing Cu and an additive metal other than 1 to 35% by weight of Cu and having an overall melting point lower than that of Cu. be able to. In addition, examples of the metal component other than Cu in the low-temperature copper conductor paste include at least one of Ti, Mn, and Ge.

  The conductor layer is a conductor composition composed of Cu and one or more additive metals other than Cu, and the additive metal is a metal that makes the melting point of the conductor composition lower than the melting point of Cu and contains the additive metal The amount is preferably 0.8 to 30% by weight. Examples of metal components other than Cu include at least one of Ti, Mn, and Ge.

  The conductor layer is a metal powder capable of forming a conductor layer after firing, and is preferably obtained by firing a conductor paste using a powder having an average particle size of 0.1 to 10 μm. As the particle size of the metal powder becomes smaller, firing at a low temperature becomes possible. That is, the cost required for firing can be reduced. Here, the metal powder may be either an alloy powder having a conductor layer composition or a mixed powder weighed so that pure metal and / or alloy powder has the conductor layer composition.

  Moreover, it is preferable to have an oxide, glass powder, and a vehicle in the raw material of a conductor layer. By baking the paste having these, densification of the conductor layer is promoted.

  The glass in which the glass particles are dispersed in the conductor layer to form the glass layer is preferably manufactured using a glass raw material having the same composition as that of the glass particle raw material as a main component. Glass particles are dispersed in a conductor layer obtained by firing a paste having glass powder. And since the glass raw material which is a raw material of a glass layer becomes the same composition as this glass powder, the glass particle exposed to the surface of a conductor layer and a glass layer are integrated, and a conductor layer is adhere | attached on the base-material surface. More preferably, the glass layer is manufactured from a glass raw material.

The thick film circuit board of the present invention can have a resistor in addition to the glass layer and the conductor layer. As the resistor, a conventionally known resistor can be used, for example, a RuO ₂ resistor.

  The thick film circuit board of the present invention preferably has an overcoat glass on the conductor layer. By forming the overcoat glass on the conductor layer, the conductor layer is not exposed, and damage to the conductor layer is suppressed.

  Since the conductive film is formed on the glass layer, the thick film circuit board of the present invention is preferably used for a substrate that requires a land having a small land size. In particular, it is preferable to use for a substrate having a distance between lands of 0.3 mm or less.

  The manufacturing method of the thick film circuit board of the present invention is not particularly limited. For example, it can be manufactured by the following manufacturing method.

  The manufacturing method of the thick film circuit board of the present invention includes a glass layer forming step of forming a glass layer by firing in a state where a glass material is disposed on a substrate surface, and a conductive paste capable of forming a conductor layer after firing. And a conductor layer forming step of firing in a state of being disposed on the layer. By performing the glass layer forming step and the conductor layer forming step, the thick film circuit board of the present invention can be manufactured.

  The glass layer forming step is preferably a step of printing and baking a pasty glass material on the surface of the substrate. Moreover, it is preferable that a conductor layer formation process is a process of printing and baking a low-temperature copper conductor paste.

The thick film circuit board of the present invention is a metal powder capable of forming a conductor layer after firing, and is obtained by firing a conductor paste using a powder having an average particle size of 0.1 to 10 μm at 600 to 700 ° C. A thick film circuit board having a conductor layer for conducting electricity formed on a substrate is preferable.

  The conductor layer is a metal powder capable of forming a conductor layer after firing, and is obtained by firing a conductor paste using a powder having an average particle size of 0.1 to 10 μm at 600 to 700 ° C. By reducing the particle size of the metal powder, firing at a low temperature of 600 to 700 ° C. is possible. That is, the cost required for firing can be reduced. Here, the metal powder may be either an alloy powder having a conductor layer composition or a mixed powder weighed so that pure metal and / or alloy powder has the conductor layer composition.

  As the base material, a base material used in a conventionally known circuit board can be used. As the substrate, for example, an alumina ceramic substrate in which a ceramic such as alumina is formed in a plate shape can be used.

  The conductor layer is a member through which electricity flows in the thick film circuit board. The conductor layer is formed on the surface of the base material according to a predetermined circuit pattern.

In the thick film circuit board of the present invention, it is preferable that at least the peripheral portion of the conductor layer to which the element is bonded is covered with a protective film made of glass or resin . Since the protective coating covers the peripheral portion of the conductor layer, the protective coating regulates the displacement of the peripheral portion even if the peripheral portion of the conductor layer is about to be displaced. As a result, it is possible to suppress the peripheral edge from being peeled off from the base material. That is, even if the conductor layer is easily peeled off from the base material, the peripheral portion can be prevented from peeling off from the base material.

  Moreover, it becomes possible to reduce the contact area of a protective film and a conductor layer because a protective film coat | covers the peripheral part of the conductor layer to which an element is joined at least. Since the contact area can be reduced, diffusion of elements constituting the protective film into the conductor layer (or resistor) can be suppressed, and deterioration of the electrical conduction characteristics of the conductor layer (or resistor) can be suppressed.

  Furthermore, since the protective film exhibits the same function as the overcoat glass on the conductor layer, damage to the conductor layer can be suppressed when the thick film circuit board is used.

  The protective film is made of glass or resin. The glass or resin for forming the protective film is not particularly limited as long as it can be formed on the surface of the substrate and can fix the conductor layer. For example, as the glass for forming the protective film, ZnO-based or PbO-based glass can be used.

In the thick film circuit board of the present invention, it is preferable that the peripheral edge of the conductor layer is covered with a protective film . In other words, the protective coating covers the peripheral portion of the conductor layer, so that the protective coating regulates the displacement of the peripheral portion even if the peripheral portion of the conductor layer is about to be displaced. As a result, the displacement of the peripheral portion of the conductor layer is suppressed, and peeling caused by the displacement of the peripheral portion is suppressed.

The thick film circuit board of the present invention preferably has a base material, a conductor layer, and a protective film .

  The conductor layer is preferably formed by firing a low-temperature copper conductor paste containing a metal component composed of Cu and one or more additive metals other than Cu having a total of 1 to 35% by weight. Here, the additive metal is a metal that makes the melting point of the metal component lower than the melting point of Cu. The low-temperature copper conductor paste shrinks when fired, and stress remains in the conductor layer obtained by firing. This residual stress is a force toward the central portion (portion where the conductor layer is thick) at the peripheral portion. That is, the conductor layer formed by firing the low-temperature copper conductor paste is easily peeled off from the base material at the peripheral edge. For this reason, it was difficult to obtain sufficient soldering strength.

  Here, in the low-temperature copper conductor paste for forming the conductor layer, it is preferable to use at least one of Ti, Mn, and Ge as the additive metal other than Cu.

  Firing of the Cu-based conductor is performed in an inert gas atmosphere. Here, the inert gas atmosphere may be any gas that does not react with the Cu-based conductor, and examples thereof include nitrogen, helium, neon, argon, and the like. It is preferable.

  The protective coating is preferably formed by firing in a state where the peripheral portion of the conductor layer is covered after the formation of the conductor layer.

  The softening point of the glass forming the protective film is preferably lower than the firing temperature of the conductor layer. When the glass softening point is lower than the firing temperature of the conductor layer, the protective film can be coated after firing the conductor layer. Moreover, even if the peripheral part of the conductor layer has peeled off from the substrate surface, the protective coating penetrates into the gap between the substrate surface and the conductor layer, and the penetrated coating adheres the substrate and the conductor layer. It will be. As a result, peeling of the conductor layer does not occur.

  The conductor paste preferably has an oxide, glass powder, and vehicle. By baking the paste having these, densification of the conductor layer is promoted.

  It is preferable that the conductive paste has a glass powder and the protective coating is made mainly of a glass raw material having the same composition as the glass powder raw material. Glass particles are dispersed in a conductor layer obtained by firing a paste having glass powder. And since the glass raw material which is a raw material of a glass layer becomes the same composition as this glass powder, the glass particle exposed to the surface of the conductor layer and the protective film are integrated, and a conductor layer is adhere | attached on the base-material surface. More preferably, the glass layer is manufactured from a glass raw material.

  The conductor layer is a conductor composition composed of Cu and one or more additive metals other than Cu, and the additive metal is a metal that makes the melting point of the conductor composition lower than the melting point of Cu and contains the additive metal The amount is preferably 0.8 to 30% by weight. Examples of metal components other than Cu include at least one of Ti, Mn, and Ge.

  The thick film circuit board of the present invention can have a resistor and an Ag-based conductor in addition to the Cu-based conductor layer and the protective film.

  The resistor is preferably fired at a temperature higher than the firing temperature of the conductor layer. That is, it is preferable to fire the resistor in advance at a predetermined position on the surface of the substrate, and then fire the conductor layer. By forming the resistor on the substrate in advance, the firing conditions of the resistor are not limited. That is, a resistor fired in an air atmosphere can be used.

A resistor fired at a temperature equal to or higher than the firing temperature of the conductor layer can be used for the thick film circuit board of the present invention. In particular, it is preferable to use an inexpensive RuO ₂ resistor. This RuO ₂ resistor was reduced and decomposed by nitrogen gas, which is the firing atmosphere of the conductor layer, when the copper conductor fired at a temperature of 900 ° C. or higher formed the conductor layer. When the baking is performed at 750 ° C. or lower, reductive decomposition of the resistor by nitrogen gas does not occur. That is, the RuO ₂ resistor can be fired in the air atmosphere, and the cost required for manufacturing can be reduced.

  The manufacturing method of the thick film circuit board of the present invention is not particularly limited. For example, it can be manufactured by the following manufacturing method.

  The method for producing a thick film circuit board of the present invention includes a conductor layer forming step of firing a conductor paste capable of forming a conductor layer after firing on a substrate surface, and a coating material capable of forming a protective coating after firing. And a protective film forming step in which the protective film is formed by baking in a state where the film is disposed on the peripheral portion of the conductor layer. By performing the conductor layer forming step and the protective film forming step, the thick film circuit board of the present invention can be manufactured.

  The conductor layer forming step is preferably a step of printing and baking a low-temperature copper conductor paste. Moreover, it is preferable that a protective film formation process is a process of printing and baking a paste-form glass material.

  Hereinafter, the present invention will be described using examples.

  As an example, a thick film circuit board was prepared.

(Example 1)
A plate-like substrate 1 made of alumina ceramics was prepared using a conventionally known method. Then, a glass material, a resistor material, and an Ag-based conductor material were printed on the surface of the plate-like substrate 1 and fired at 850 ° C. This calcination was performed in Air. The glass material is a ZnO-based or PbO-based glass material, the resistor material is a RuO ₂ -based resistor material, and the Ag-based conductor material is an Ag or Ag-Pd-based conductor material. Can be used. These materials became the glass layer 3, the resistor 5, and the Ag-based conductor 6 by firing. Here, the softening point of the glass constituting the glass layer 3 was 600 ° C. The cross section of the base material after firing is shown in FIG. The Ag-based conductor 6 functions as a bonding pad conductor. The bonding pad conductor fixes the electric element to the thick film circuit board and electrically connects the circuit and the element when the electric element is installed in the thick film circuit.

Subsequently, a Cu-based conductor material was printed on the surface of the glass layer 3 and fired at 600 to 700 ° C. in an N ₂ atmosphere. By this firing, a Cu-based conductor 2 was formed on the glass layer 3. The cross section of the base material after firing is shown in FIG. As shown in FIG. 2, the Cu-based conductor 2 has a conductor 21 formed entirely on the surface of the glass layer 3, a peripheral portion formed on the glass layer 3, and a central portion in close contact with the substrate 1. And the conductor 22 formed in this manner.

Thereafter, an overcoat glass material was printed and fired at 600 ° C. in an N ₂ atmosphere. The overcoat glass 4 was formed by this baking. The cross section of the base material after firing is shown in FIG.

  Thus, this example was manufactured.

In the thick film circuit board of this example, a Cu-based conductor layer 2 is formed on a glass layer 3. At this time, the glass layer 3 has the glass layer 3 on which the entire conductor layer 2 is formed, and the glass layer 3 on which only the peripheral edge of the conductor layer 2 is formed. In addition, the Cu-based conductor layer 2 was not confirmed to be peeled off at the periphery in both the conductor 21 and the conductor 22. That is, in the thick film circuit board of this example, peeling from the base material at the periphery of the conductor layer does not occur. As a result, the thick film circuit board of the present example has a sufficient soldering strength.

( Reference example )
Similar to Example 1, a plate-like substrate 1 made of alumina ceramics was prepared. Then, a resistor material and an Ag-based conductor material were printed on the surface of the plate-like substrate 1 and baked at 850 ° C. This calcination was performed in Air. As the resistor material, a RuO ₂ based resistor material can be used, and as the Ag based conductor material, an Ag or Ag—Pd based conductor material can be used. These materials became the resistor 5 and the Ag-based conductor 6 by firing.

Subsequently, a Cu-based conductor material was printed on the surface of the substrate 1 and fired at 600 to 700 ° C. in an N ₂ atmosphere. By this firing, a Cu-based conductor 2 was formed on the substrate 1. The cross section of the base material after firing is shown in FIG. As shown in FIG. 4, in the Cu-based conductor 2, peeling (raising) from the surface of the base material 1 was observed at the peripheral portion 23.

Then, the glass material is applied in a state of covering the periphery of the conductor layer 2 of Cu-based and calcined in N ₂ atmosphere at 600 ° C.. The protective film 7 was formed by this baking. The cross section of the base material after firing is shown in FIG.

Thus, the present reference example was manufactured.

In this reference example , the peripheral portion of the Cu-based conductor 2 formed on the surface of the substrate 1 is covered with the protective coating 7. That is, even if the peripheral edge 23 of the Cu-based conductor 2 is peeled off from the surface of the base material 1, the protective coating 7 covers the peripheral edge 23, so that the shear stress resistance is greatly improved. The protective coating 7 also enters the gap between the peripheral portion 23 and the surface of the base material 1 and also serves to fix the peripheral portion 23 on the base material 1.

Furthermore, since the protective film 7 is formed only in the peripheral part of the Cu-based conductor 2 in this reference example , diffusion of elements constituting the protective film 7 into the Cu-based conductor 2 is suppressed.

As a result, the thick film circuit board of this reference example has a sufficient soldering strength.

( Example 2 )
This example is a thick film circuit board in which the configurations of Example 1 and Reference Example 1 are used in combination.

  First, as in Example 1, a plate-like substrate 1 made of alumina ceramics was created. Then, a glass material, a resistor material, and an Ag-based conductor material were printed on the surface of the plate-like substrate 1 and fired at 850 ° C. This calcination was performed in Air. These materials became the glass layer 3, the resistor 5, and the Ag-based conductor 6 by firing. Here, the softening point of the glass constituting the glass layer 3 was 600 ° C. A cross section of the base material after firing is shown in FIG.

Subsequently, a Cu-based conductor material was printed on the surface of the substrate 1 and the glass layer 3 and fired at 600 to 700 ° C. in an N ₂ atmosphere. By this firing, a Cu-based conductor 2 was formed on the substrate 1. A cross section of the base material after firing is shown in FIG. As shown in FIG. 7, in the Cu-based conductor 2 formed on the surface of the base material 1, peeling (raising) from the surface of the base material 1 was observed at the peripheral portion 23. In addition, peeling was not seen in the peripheral part 23 of the Cu-type conductor layer 2 formed on the glass layer 3. FIG.

Then, the glass material is applied in a state of covering the periphery 23 of the conductive layer 2 of Cu system formed on the surface of the substrate 1 was baked in an N ₂ atmosphere at 600 ° C.. The protective film 7 was formed by this baking. The formed protective film 7 also functions as the overcoat glass 4 of Example 1 depending on the position where it is formed. A cross-section of the base material after firing is shown in FIG.

  Thus, this example was manufactured.

The present embodiment exhibits the same effect as that of the first embodiment . That is, even when the Cu-based conductor 2 is formed on the glass layer 3 or when the Cu-based conductor 2 is formed on the surface of the base material 1, the conductor 2 is formed at any peripheral edge 23. Peeling is suppressed. As a result, the thick film circuit board of the present example has a sufficient soldering strength.

  On the other hand, since the conventional thick film circuit board does not use the glass layer 3 or the protective coating 7, the peripheral portion 23 of the Cu-based conductor 2 is peeled off from the surface of the substrate 1. This is illustrated in FIG.

That is, the thick film circuit boards of Examples 1 and 2 which are the thick film circuit boards of the present invention ensure sufficient soldering strength by suppressing peeling of the peripheral portion of the conductor layer (Cu-based conductor 2). It is what has been.

It is the figure which showed the cross section of the base material in the state in which the glass layer was formed in Example 1. FIG. It is the figure which showed the cross section of the base material in the state in which the conductor layer was formed in Example 1. FIG. It is the figure which showed the cross section of the thick film circuit board of Example 1. FIG. It is the figure which showed the cross section of the base material in the state in which the conductor layer was formed in the reference example . It is the figure which showed the cross section of the thick film circuit board of a reference example . It is the figure which showed the cross section of the base material in the state in which the glass layer was formed in Example 2. FIG. It is the figure which showed the cross section of the base material in the state in which the conductor layer was formed in Example 2. FIG. It is the figure which showed the cross section of the thick film circuit board of Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Cu-type conductor 23 ... Peripheral part 3 ... Glass layer 4 ... Overcoat glass 5 ... Resistor 6 ... Ag-type conductor 7 ... Protective film

Claims (5)

An insulating substrate;
A glass layer made of glass formed on the substrate surface;
A conductor layer for conducting electricity formed on the glass layer;
Have
The conductor layer is a metal powder capable of forming the conductor layer after firing, a powder having an average particle diameter of 0.1 to 10 μm, and at least one of Mn, Ti, and Ge is added. Baked,
The thick film circuit board, wherein the glass layer is at least at a peripheral edge of the conductor layer and has a size protruding from the conductor layer.   The thick film circuit board according to claim 1, wherein the glass layer is formed at least on a portion where a component is mounted on the conductor layer. The thick film circuit board according to claim 2, wherein a softening point of the glass forming the glass layer is lower than a firing temperature of the conductor layer. 3. The thick film circuit according to claim 2, wherein the glass particles are dispersed in the conductor layer, and the glass forming the glass layer is manufactured using a glass raw material having the same composition as a raw material of the glass particles as a main component. substrate. An insulating substrate;
A glass layer made of glass formed on the substrate surface;
A conductor layer for conducting electricity formed on the glass layer;
Have
The thick film circuit board, wherein the glass layer is formed only in a peripheral portion of the conductor layer and has a size protruding from the conductor layer.

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