JP2003347462A - Method for manufacturing circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a circuit board for reducing the man-hours of manufacturing by simultaneously firing a plurality of materials by changing the order of the firing of the respective materials. <P>SOLUTION: A pad conductor 1 for wire bonding and a resistor 3 are respectively printed on a substrate (S1, S2), and they are simultaneously fired (S3). Therefore, it is possible to reduce the man-hours of manufacturing compared with a conventional method for separately firing the pad conductor 1 and the resistor 3. Also, the pad conductor 1 and the resistor 3 are printed with a predetermined pattern so as not to be overlapped with each other on a substrate 5. Therefore, it is possible to prevent any failure that any crack is generated on an alloy layer interface by mutually diffusing those materials even at the time of simultaneously firing those materials. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a circuit board, and more particularly to a method for manufacturing a thick-film circuit board by printing and firing a conductor or a resistor on the board.

[0002]

2. Description of the Related Art Conventionally, a thick-film circuit board having a pad conductor 11, a wire conductor 12, a resistor 13, and a protective glass 14 provided on a substrate 15 as shown in FIG. 16 was manufactured by performing the steps shown in FIG. 9 and FIG. Here, FIG.
FIG. 11 is a flowchart showing a flow of each step in a conventional method of manufacturing the thick film circuit board 16, and is a flowchart of FIG.
(D) is a side view which shows the state of the board | substrate 15 in each baking process.

That is, as shown in FIG. 9, first, a substrate 15 made of a material such as alumina is prepared, and a conductor paste, which is a material of the pad conductor 11 for wire bonding, is printed on the substrate 15 in a desired pattern ( S51), 850
The pad conductor 11 is formed by baking at a temperature of ° C. (S52) (FIG. 10A). Next, a conductor paste, which is a material of the wiring conductor 12, is printed on the substrate 15 in a desired pattern (S53) and baked at 850 ° C. (S5).
4), forming a wiring conductor 12 (FIG. 10B), followed by printing a resistor paste, which is a material of the resistor 13, on the substrate 15 in a desired pattern and baking it at 850 ° C. (FIG. 10C) Finally, a glass material, which is a material of the protective glass 14, is printed so as to cover the resistor 13, and is fired at 650 ° C. to form the protective glass 14 (FIG. 10C). 10 (d)), the thick film circuit board 16 is completed (FIG. 8) The firing temperature of the protective glass 14 is set to 650 ° C., which is lower than the firing temperature of other materials, because the firing is already performed. This is in order to suppress the occurrence of a so-called firing drift in which the resistance value fluctuation is caused by further firing the resistor 13 that has been made.

[0004]

However, in the above-mentioned conventional method for manufacturing a thick film circuit board, the process of printing and firing each material must be repeated four times, and the thick film circuit board is not manufactured. There is a problem that a large number of man-hours are required for manufacturing. In particular, the number of steps in the firing step is 1
Since it takes about 4 hours, it takes about 4 hours for firing in the entire manufacturing process.

[0005] In view of such problems, conventionally, to reduce the number of firing steps and to reduce costs, studies have been made on simultaneous firing of three of pad conductors, wiring conductors, and resistors. However, the pad conductor, the wiring conductor, and the resistor all have a high firing temperature of 800 to 900 ° C.,
When co-firing, there is a problem that diffusion between the overlapping materials occurs. In particular, between the pad conductor and the wiring conductor, both materials are diffused during firing, an alloy layer grows, cracks are generated at the interface of the alloy layer, and a disconnection failure may occur. On the other hand, between the wiring conductor and the resistor, a problem that the wiring conductor diffuses into the resistor and the resistance value is defective easily occurs. Under such circumstances, it has not been possible to realize simultaneous firing of each material.

SUMMARY OF THE INVENTION In view of the above problems, the present invention is to solve the problem of providing a method of manufacturing a circuit board in which the number of manufacturing steps is reduced by simultaneously firing a plurality of materials while changing the firing order of each material. Make it an issue.

[0007]

According to a first aspect of the present invention, there is provided a circuit board manufacturing method, wherein a pad conductor for wire bonding, a wiring conductor, and a resistor are printed on the substrate. A method of manufacturing a circuit board by firing and printing the pad conductor and the resistor on the substrate and firing them simultaneously.

Accordingly, by simultaneously firing the pad conductor and the resistor, the number of firings can be reduced and the number of manufacturing steps can be reduced. In addition, since the pad conductor and the resistor are printed on the substrate in a predetermined pattern having no overlap, even if co-firing, these materials interdiffuse and cracks occur at the interface of the alloy layer. Does not occur.

In a second aspect of the present invention, the wiring conductor is printed and fired after simultaneous firing of the pad conductor and the resistor.

Therefore, after the pad conductor and the resistor are fired, the wiring conductor having an overlapping portion with the pad conductor and the resistor is printed and fired, so that mutual diffusion between materials is prevented.

According to a third aspect of the present invention, in the method of manufacturing a circuit board, after simultaneously firing the pad conductor and the resistor, a protective glass is further printed on the substrate, and the wiring conductor and the protective glass are simultaneously fired. It is characterized by doing.

Accordingly, by simultaneously firing the protective glass and the wiring conductor formed after the simultaneous firing of the pad conductor and the resistor, the number of firings can be further reduced, and the number of manufacturing steps can be further reduced.

According to a fourth aspect of the present invention, in the circuit board manufacturing method, the pad conductor and the resistor are fired at a first firing temperature, and the wiring conductor and the protective glass are fired at a temperature lower than the first firing temperature. It is characterized by firing at a low second firing temperature.

Therefore, the wiring conductor and the protective glass are
Since the firing is performed at a second firing temperature lower than the first firing temperature that is the firing temperature of the pad conductor and the resistor, the resistor fired in the previous process is replaced with the wiring conductor and protective glass firing process in the subsequent process. In this case, the occurrence of a so-called firing drift in which the resistance is changed by further firing is prevented.

In the method of manufacturing a circuit board according to a fifth aspect, the first firing temperature is set to 800 to 900 ° C., and the second firing temperature is set to 500 to 700 ° C.

Therefore, the pad conductor and the resistor are 800
The firing is preferably performed at a temperature of up to 900 ° C., and the wiring conductor and the protective glass are preferably fired at a temperature of 500 to 700 ° C. while suppressing occurrence of firing drift in the resistor.

According to a sixth aspect of the present invention, in the method of manufacturing a circuit board, a material that can be fired at the second firing temperature is used as the wiring conductor.

Accordingly, it is possible to satisfactorily fire the wiring conductor and the protective glass simultaneously while preventing the firing drift of the resistor.

In the method for manufacturing a circuit board according to a seventh aspect of the present invention, a material having a decomposition temperature equal to or lower than a sintering start temperature of the protective glass is used as a volatile component contained in the wiring conductor.

Therefore, when simultaneously sintering the wiring conductor and the protective glass, sintering of the protective glass starts after the volatile component contained in the wiring conductor is decomposed, so that it is provided so as to cover at least a part of the wiring conductor. A pinhole can be prevented from being formed in the protective glass.

In a preferred embodiment of the present invention, the circuit board is manufactured by printing and firing a wiring conductor, a resistor, and a protective glass on the board, respectively. A wiring conductor and the protective glass are printed on the substrate, respectively, and are fired simultaneously.

Therefore, by simultaneously firing the wiring conductor and the protective glass, the number of firings can be reduced, and the number of manufacturing steps can be reduced.

According to a ninth aspect of the present invention, in the method of manufacturing a circuit board, after the printing and firing of the resistor, printing and simultaneous firing of the wiring conductor and the protective glass are performed.

Therefore, after printing and firing the resistor, printing and simultaneous firing of the wiring conductor overlapping the resistor and the protective glass covering the resistor are performed, so that the materials are not overlapped in the overlapping portion of the resistor and the wiring conductor. Is prevented from occurring.

According to a tenth aspect of the present invention, in the circuit board manufacturing method, the resistor is fired at a first firing temperature, and the wiring conductor and the protective glass are fired at a second firing temperature lower than the first firing temperature. It is characterized by firing at a firing temperature.

Therefore, the wiring conductor and the protective glass are
Since the firing is performed at a second firing temperature lower than the first firing temperature which is the firing temperature of the resistor, the resistor fired in the previous process is further fired in the subsequent process of firing the wiring conductor and the protective glass. Thus, a so-called firing drift in which the resistance value changes is prevented.

The method of manufacturing a circuit board according to claim 11 is characterized in that the first sintering temperature is 800 to 900 ° C. and the second sintering temperature is 500 to 700 ° C.

Therefore, the resistor is fired well at 800 to 900 ° C., and the wiring conductor and the protective glass are 500 to 7 mm.
At 00 ° C., sintering is performed favorably while suppressing the occurrence of firing drift in the resistor.

A twelfth aspect of the present invention is a method of manufacturing a circuit board, wherein a material that can be fired at the second firing temperature is used as the wiring conductor.

Therefore, it is possible to satisfactorily fire the wiring conductor and the protective glass simultaneously while preventing the firing drift of the resistor.

According to a thirteenth aspect of the present invention, in the method for manufacturing a circuit board, a material having a decomposition temperature equal to or lower than a sintering start temperature of the protective glass is used as a volatile component contained in the wiring conductor.

Therefore, when simultaneously sintering the wiring conductor and the protective glass, sintering of the protective glass starts after the volatile component contained in the wiring conductor is decomposed, so that it is provided so as to cover at least a part of the wiring conductor. A pinhole can be prevented from being formed in the protective glass.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a method for manufacturing a thick film circuit board according to the present invention will be described with reference to the drawings.

First, a method of manufacturing a thick-film circuit board according to a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a flowchart showing the overall flow of the manufacturing process of the thick film circuit board in the present embodiment.
FIGS. 2A to 2D are side views showing the state of the substrate 5 in each firing step. FIG. 3 is a side view showing a thick film circuit board manufactured by the manufacturing method of the present embodiment.

First, a substrate 5 made of a material such as alumina for forming a conductor thick film or the like is prepared (see the flowchart of FIG. 1, and the following steps are the same).

First, a conductor paste such as Ag, Ag-Pd, Au or the like, which is the material of the pad conductor 1 for wire bonding, is printed on the substrate 5 in a desired pattern (S1). printed on the substrate 5 a resistor paste of RuO ₂ or the like is in a desired pattern (S2). Here, the pad conductor 1 and the resistor 3 are printed on the substrate 5 in a predetermined pattern having no overlap. The printing of the pad conductor 1 and the resistor 3 is performed by a known printing method such as screen printing (the same applies to other printing processes described later).
In addition, any of S1 and S2 may be performed first.

Subsequently, the pad conductor 1 and the resistor 3 are
Simultaneous firing at 0 to 900 ° C (first firing temperature) (S
3). The baking time is appropriately set depending on conditions such as the size of the substrate, and is, for example, about one hour (the same applies to other baking steps). At this time, since the pad conductor 1 and the resistor 3 do not have an overlapping portion, the two materials do not mutually diffuse even if co-firing is performed. Therefore, cracks occur at the layer interface due to the growth of the alloy layer. No failures occur.

Next, Cu, Ag which are the materials of the wiring conductor 2 are used.
Is printed on the substrate 5 in a desired pattern (S4), and then baked at 800 to 900 ° C. (S5) to form the wiring conductor 2 (FIG. 2B). Here, since the wiring conductor 2 is provided for electrically connecting the pad conductor 1 and the resistor 3, the wiring conductor 2 is printed in a predetermined pattern overlapping with these.

Finally, PbO which is a material of the protective glass 4 is used.
A glass material such as a system is printed so as to cover at least a part of the resistor 3 and the wiring conductor 2 on the substrate 5 (S6), 50
By baking at 0 to 700 ° C. (second baking temperature) (S7), the protective glass 4 is formed (FIG. 2C). Here, the protective glass 4 is provided to shield and protect the resistor 3 from external moisture and atmosphere.
The firing temperature of the protective glass 4 is set at 500 to 700 ° C., which is lower than the firing temperature of other materials, because the resistor 3 fired in the previous step is fired further in the subsequent step. This is to suppress the occurrence of the so-called firing drift in which the resistance value fluctuates.

Through the above steps S1 to S7, the thick film circuit board 6 shown in FIG. 3 is completed.

As is clear from the above, according to the present embodiment, the pad conductor 1 and the resistor 3 are simultaneously fired, so that the number of firing steps is reduced from four in the conventional method to three.
And the number of manufacturing steps for the thick film circuit board can be reduced.

Next, a method of manufacturing a thick film circuit board according to a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the number of manufacturing steps is reduced by simultaneously firing the wiring conductor and the protective glass.

FIG. 4 is a flowchart showing the overall flow of the manufacturing process of the thick film circuit board in this embodiment.
FIGS. 5A to 5C are side views showing the state of the substrate 5 in each firing step.

First, a substrate 5 made of a material such as alumina for forming a conductor thick film or the like is prepared (see the flowchart of FIG. 4, the same applies to the following steps).

First, a conductor paste such as Ag, Ag-Pd, or Au, which is a material of the pad conductor 1 for wire bonding, is printed on the substrate 5 in a desired pattern (S11).
Subsequently, the pad conductor 1 is formed by firing at 800 to 900 ° C. (first firing temperature) (S12) (FIG. 5A). The baking time is appropriately set depending on conditions such as the size of the substrate, and is, for example, about one hour (the same applies to other baking steps).

Next, a resistor paste such as RuO _2, which is a material of the resistor 3, is printed on the substrate 5 in a desired pattern (S 13), followed by baking at 800 to 900 ° C. (S 14). And the resistor 3 (FIG. 5)
(B)).

Next, Cu and Ag which are the materials of the wiring conductor 2 are used.
Is printed in a desired pattern on the substrate 5 (S15), and PbO, which is a material of the protective glass 4, is covered so as to cover at least a part of the resistor 3 and the wiring conductor 2.
A glass material such as a system is printed (S16). Here, Cu, Ag, or the like used as the material of the wiring conductor 2 in the present embodiment has a property that it can be fired at a low temperature of about 500 to 700 ° C.

Finally, the wiring conductor 2 and the protective glass 4 are
Simultaneous firing at 500 to 700 ° C. (second firing temperature) (S17) forms the wiring conductor 2 and the protective glass 4 (FIG. 5C).

Through the above steps S11 to S17, the thick film circuit board 6 shown in FIG. 3 is completed.

When the wiring conductor 2 and the protective glass 4 are co-fired, volatile components (for example,
A pinhole is formed in the protective glass 4 by the resin material or the solvent), which may cause a decrease in moisture resistance. Therefore, it is desirable to use a material having a decomposition temperature lower than the sintering start temperature of the protective glass 4 as a volatile component in the wiring conductor 2. For example, the sintering start temperature of the protective glass 4 is 4
When the temperature is 50 ° C., a resin or a solvent having a decomposition temperature of 400 ° C. can be suitably used as a volatile component.

As is apparent from the above description, according to this embodiment, since the wiring conductor and the protective glass are simultaneously fired, the number of firing steps is reduced from four in the conventional method to three, and the thickness is reduced. The number of manufacturing steps for the membrane circuit board can be reduced.

Next, a method for manufacturing a thick film circuit board according to a third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, the number of manufacturing steps is further reduced by performing simultaneous firing of the pad conductor and the resistor and simultaneous firing of the wiring conductor and the protective glass.

FIG. 6 is a flowchart showing the entire flow of the manufacturing process of the thick film circuit board in this embodiment.
FIGS. 7A and 7B are side views showing the state of the substrate 5 in each firing step.

First, a substrate 5 made of a material such as alumina for forming a conductor thick film or the like is prepared (see the flowchart of FIG. 6, the same applies to the following steps).

First, a conductor paste such as Ag, Ag-Pd, Au or the like, which is a material of the pad conductor 1 for wire bonding, is printed on the substrate 5 in a desired pattern (S21).
Further, a resistor paste such as RuO _{2 as} a material of the resistor 3 is printed on the substrate 5 in a desired pattern (S2).
2). Here, the pad conductor 1 and the resistor 3 are overlapped on the substrate 5 and are printed in a predetermined pattern. The printing of the pad conductor 1 and the resistor 3 is performed by a known printing method such as screen printing (the same applies to other printing processes).
In addition, any of steps S21 and S22 may be performed first.

Subsequently, the pad conductor 1 and the resistor 3 are
Simultaneous firing at 0 to 900 ° C (first firing temperature) (S2
3), forming the pad conductor 1 and the resistor 3 (FIG. 7)
(A)). The baking time is appropriately set depending on conditions such as the size of the substrate, and is, for example, about one hour (the same applies to other baking steps). At this time, since the pad conductor 1 and the resistor 3 do not have an overlapping portion, the two materials do not mutually diffuse even if co-firing is performed. Therefore, cracks occur at the layer interface due to the growth of the alloy layer. No failures occur.

Next, Cu and Ag which are the materials of the wiring conductor 2 are used.
Is printed on the substrate 5 in a desired pattern (S24), and PbO, which is a material of the protective glass 4, is covered so as to cover at least a part of the resistor 3 and the wiring conductor 2.
A glass material such as a system is printed (S25). Note that, similarly to the second embodiment, also in this embodiment, a material (Cu, Ag, etc.) that can be fired at a low temperature (500 to 700 ° C.) is used as the material of the wiring conductor 2. In order to prevent pinholes from being formed in the protective glass 4, as a volatile component in the wiring conductor 2, a material (such as a resin or a solvent) whose decomposition temperature is lower than the sintering start temperature of the protective glass 4. It is desirable to use the same as in the second embodiment.

Finally, the wiring conductor 2 and the protective glass 4 are
Simultaneous firing at 500 to 700 ° C. (second firing temperature) (S26) forms the wiring conductor 2 and the protective glass 4 (FIG. 7B).

Through the above steps S21 to S26, the thick film circuit board 6 shown in FIG. 3 is completed.

As is apparent from the above description, according to this embodiment, the pad conductor and the resistor, the wiring conductor and the protective glass are simultaneously fired, respectively, so that the number of firing steps is four times that in the conventional method. , And the number of manufacturing steps for the thick film circuit board can be further reduced.

The present invention is not limited to the above-described embodiments, and various changes can be made without departing from the gist of the present invention.

For example, the firing temperature and the firing time in each of the above embodiments are merely examples, and the optimum temperature and time should be set according to various conditions.

Further, in each of the above embodiments, the present invention is applied to a thick film circuit board provided with a pad conductor, a wiring conductor, a resistor, and a protective glass for wire bonding on the board.
The present invention can be applied to a circuit board without a pad conductor or a protective glass.

[0065]

As described above, according to the method for manufacturing a circuit board according to any one of claims 1 to 7 of the present invention, the pad conductor printed in a predetermined pattern having no overlap on the board is provided. By simultaneously firing the resistor and the resistor, the number of firings can be reduced and the number of manufacturing steps can be reduced without causing mutual diffusion of the materials.

According to the circuit board manufacturing method of the present invention, the wiring conductor and the protective glass are simultaneously fired, so that the number of firings is reduced and the number of manufacturing steps is reduced. Can be.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a flow of each step of a method for manufacturing a thick film circuit board according to a first embodiment of the present invention.

FIG. 2 is a side view of the substrate in each firing step of the first embodiment.

FIG. 3 is a side view showing the thick-film circuit board manufactured by the manufacturing method of the first embodiment.

FIG. 4 is a flowchart showing a flow of each step of a method for manufacturing a thick film circuit board according to a second embodiment.

FIG. 5 is a side view of the substrate in each firing step of the second embodiment.

FIG. 6 is a flowchart showing a flow of each step of a method of manufacturing a thick film circuit board according to a third embodiment.

FIG. 7 is a side view of the substrate in each firing step of the third embodiment.

FIG. 8 is a side view showing a conventional thick film circuit board.

FIG. 9 is a flowchart showing a flow of each step of a method for manufacturing a thick film circuit board in a conventional example.

FIG. 10 is a side view of the substrate in each firing step of the conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pad conductor, 2 ... Wiring conductor, 3 ... Resistor, 4 ... Protective glass, 5 ... Substrate, 6 ... Thick film circuit board.

Continuation of front page    F term (reference) 4E351 AA07 BB01 BB05 BB31 CC11                       CC22 CC31 DD04 DD05 DD06                       DD20 DD22 GG20                 5E314 AA06 BB06 CC07 DD06 FF02                       FF13 FF14 FF24 GG24                 5E343 AA23 BB23 BB24 BB25 BB49                       DD03 DD64 ER33 ER39 ER42                       FF11 GG08 GG11 GG20

Claims (13)

[Claims] 1. A pad conductor for wire bonding,
A method of manufacturing a circuit board by printing a wiring conductor and a resistor on a substrate, respectively, and firing the printed circuit board, wherein the pad conductor and the resistor are respectively printed on the substrate, and fired simultaneously. A method for manufacturing a circuit board. 2. The method according to claim 1, wherein printing and firing of the wiring conductor are performed after simultaneous firing of the pad conductor and the resistor. 3. The method according to claim 2, wherein after the simultaneous firing of the pad conductor and the resistor, a protective glass is further printed on the substrate, and the wiring conductor and the protective glass are simultaneously fired. Circuit board manufacturing method. 4. The method according to claim 1, wherein the pad conductor and the resistor are fired at a first firing temperature, and the wiring conductor and the protective glass are fired at a second firing temperature lower than the first firing temperature. The method for manufacturing a circuit board according to claim 3, wherein 5. The first sintering temperature is 800 to 900 ° C.
The method according to claim 4, wherein the second firing temperature is set to 500 to 700C. 6. A material that can be fired at the second firing temperature as the wiring conductor.
Or the circuit board manufacturing method according to 5. 7. The circuit board according to claim 3, wherein a material having a decomposition temperature equal to or lower than a sintering start temperature of the protective glass is used as a volatile component contained in the wiring conductor. Production method. 8. A method of manufacturing a circuit board by printing and firing a wiring conductor, a resistor, and a protective glass on a substrate, respectively, wherein the wiring conductor and the protective glass are provided on the substrate. A method for manufacturing a circuit board, comprising printing each of them and firing them simultaneously. 9. The method according to claim 8, wherein printing and simultaneous firing of the wiring conductor and the protective glass are performed after printing and firing of the resistor. 10. The method according to claim 1, wherein the resistor is fired at a first firing temperature, and the wiring conductor and the protective glass are fired at a second firing temperature lower than the first firing temperature. 10. The method for manufacturing a circuit board according to 8 or 9. 11. The first firing temperature is set to 800 to 900.
The method according to claim 10, wherein the second firing temperature is set to 500 to 700 ° C. 12. The method according to claim 10, wherein the wiring conductor is made of a material that can be fired at the second firing temperature. 13. The circuit board according to claim 8, wherein a material having a decomposition temperature equal to or lower than a sintering start temperature of the protective glass is used as a volatile component contained in the wiring conductor. Production method.