JPH0334876B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for manufacturing a multilayer thick film substrate,
In particular, the present invention relates to a device in which a conductor layer can be formed using a copper-based conductor paste.

[Technical background of the invention and its problems]

As is well known, in recent years, hybrid integrated circuits have come into widespread use in order to reduce the size and weight of electronic devices and the like. This hybrid integrated circuit is
In general, it is constructed by soldering chip-type passive elements or active elements without lead wires to a thick film substrate made by printing a conductive material and a resistive material on an insulating substrate.

FIG. 1 is for explaining a conventional manufacturing method of such a thick film substrate. That is, the first
As shown in FIG. 1B, a pair of wiring conductor layers 12 and 13 are formed on an insulating substrate 11 made of a ceramic material such as alumina, as shown in FIG. 1B. The wiring conductor layers 12 and 13 are formed by printing and firing a conductor paste containing, for example, silver-palladium (Ag/Pb) powder using a screen printing method.

Then, as shown in FIG. 1c, a resistive paste containing, for example, ruthenium oxide (RuO ₂ ) powder and glass frit is printed and fired between the pair of wiring conductor layers 12 and 13 using a screen printing method. Thus, the resistor 14 is formed.

In this case, as the resistor 14, in order to finally obtain the desired resistance value (hereinafter referred to as final resistance value), a resistor paste having an appropriate sheet resistance value is used, and the resistance value after formation (hereinafter referred to as initial resistance value) is used. The width (W) and length (L) are designed and formed in advance so that the resistance value (referred to as "value") is equal to or less than the final resistance value. Then, after that, Figure 1 d
As shown in FIG. 2, pulsed high-power laser light that can scatter the glass frit, which is a component of the resistor 14, and the conductor particles, that is, the ruthenium oxide (RuO ₂ ) powder, is irradiated inward from the side of the resistor 14. Then, a so-called trimming process is performed in which the resistor 14 is cut by the width (W), thereby decreasing the width (W) of the resistor 14 and increasing the resistance value to obtain the above-mentioned final resistance value.

Furthermore, Figure 2 shows the relationship between the ratio of the cutting amount (W') to the width (W) of the resistor 14 (W'/W [%]) and the rate of change in resistance value (P [%]). It can be seen that as the width (W) of the resistor 14 decreases, the resistance value increases.

By the way, in the thick film substrate as mentioned above,
In order to achieve high-density packaging, wiring conductor layers are formed in multiple layers with insulating layers interposed therebetween.

On the other hand, the above silver-palladium conductor paste has impedance (conductor resistance) per unit volume.
It has various problems, such as being as high as 20 to 50 [mΩ], easily causing insulation deterioration due to migration of silver due to moisture absorption, and being economically disadvantageous because it is a noble metal. Therefore, in recent years, it has been considered to use a copper-based conductive paste instead of the silver-palladium-based conductive paste. This copper-based conductor paste can form a conductor with a low impedance of 2 to 5 [mΩ] per unit volume when fired in a nitrogen gas atmosphere to the extent that the copper does not oxidize, and is also economically advantageous. It has the advantage of being

However, when using a copper-based conductor paste, there is currently no material developed for forming a resistor, that is, a resistance paste, that can be fired in a nitrogen gas atmosphere to obtain a resistance value within a practical range. It is something that has not been done yet. In other words, when current resistance pastes are fired in a nitrogen gas atmosphere, their resistance values vary widely, and in situations where laser cutting is the only way to obtain the final resistance value as described above, it is not possible to bake them in air. As shown in FIGS. 3a and 3b, a silver-palladium based conductor paste and a copper based conductive paste, both of which have little variation in resistance value, had to be used in combination.

In FIGS. 3a and 3b, a silver-palladium based conductive paste is printed on an insulating substrate 17 made of a ceramic material such as alumina and fired in air to form a lower conductor 18. Next, a glass dielectric-based insulating paste is printed as the insulating layer 19 so as to cover a predetermined portion of the lower conductor 18, and a ruthenium oxide-based resistance paste is printed as the resistor 20. are simultaneously fired in the air. Thereafter, a copper-based conductor paste is printed on the insulating layer 19 so as to be substantially orthogonal to the lower conductor 18, and is fired in a nitrogen gas atmosphere to form the upper conductor 21. Finally, laser cutting is performed. to obtain the final resistance value.

In other words, in the past, a silver-palladium conductor paste and a copper conductor paste were mixed, and the number of firings in a nitrogen gas atmosphere was reduced as much as possible.
This is intended to suppress large variations in the resistance value of the resistor 20.

[Purpose of the invention]

This invention was made in consideration of the above circumstances, and it is possible to easily increase or decrease the resistance value of a resistor to form a resistor having a final resistance value, and is extremely effective in promoting mass production. An object of the present invention is to provide a method for manufacturing a good multilayer thick film substrate.

[Summary of the invention]

That is, the method for manufacturing a multilayer thick film substrate according to the present invention includes a first step of printing a resistor paste on an insulating substrate and baking it in air to form a resistor; a second step of printing and baking a conductive paste and an insulating paste on a substrate to form a conductive layer and an insulating layer; and a second step of not scattering conductive particles and glass components in the resistor to the resistor after this second step. a first treatment step of reducing the resistance value of the resistor by irradiating a laser beam with a relatively low power; and a laser with a high power enough to scatter conductive particles and glass components in the resistor to the resistor. a second step of irradiating light to increase the resistance value of the resistor;
By providing a third process that selectively performs the above treatment process and the third process, it is possible to easily increase or decrease the resistance value of the resistor to form a resistor having a final resistance value, thereby making mass production more effective. It was designed so that it could be promoted.

[Embodiments of the invention]

Before explaining one embodiment of the present invention, the principle of the present invention will be briefly explained below. That is, on an insulating substrate 22 made of a ceramic material such as alumina, as shown in FIG. 4a,
As shown in FIG. 4b, a pair of wiring conductor layers 23,
Form 24. These wiring conductor layers 23 and 24 are
For example, it is formed by printing a conductive paste containing silver-palladium-based (Ag/Pd) powder using a screen printing method and firing it for 10 minutes at a peak temperature of 850 [° C.].

Then, as shown in FIG. 4c, a resistance paste (for example, modified nitrile rubber) containing, for example, ruthenium oxide (RuO ₂ ) powder and glass frit is applied between the pair of wiring conductor layers 23 and 24 using a screen printing method. The resistor 25 is formed by printing at a peak temperature of 850 [° C.] for 10 minutes.

Here, as shown by hatching in Figure 4d,
The resistor 25 is irradiated with a YAG laser with a low output power that does not scatter the glass component and conductor particles, that is, ruthenium oxide (RuO ₂ ) particles, while reciprocating between the wiring conductor layers 23 and 24. As a result, the resistance value (initial resistance value) of the resistor 25 can be reduced in accordance with the number of laser irradiations. The reason for this is that the resistor 25 once sintered on the insulating substrate 22 has a low output power as described above.
When irradiated with YAG laser, the ruthenium oxide (RuO ₂ ) particles, which are conductive particles, and the glass component are separated, and the conductive particles gather together, forming the resistor 25.
This is because the conductivity of the metal is promoted. In this case, for example, the YAG laser has an output of 15
[A] Good experimental results were obtained when the surface of the resistor 25 was irradiated at an irradiation speed of 30 [mm/sec].

Here, FIGS. 5 to 7 show the number of YAG laser irradiations (N) obtained experimentally, respectively.
This shows the relationship between the resistance value (R) and the resistance value (R). In other words, Figure 5 shows the case where a YAG laser is irradiated to a resistor with a sheet resistance value of 100 [Ω], and the resistance value, which was 120 [Ω] before laser irradiation, changes depending on the number of irradiations (N). It decreased to 20 [Ω] after 5 irradiations. Also, Figure 6 shows the sheet resistance value 10
This shows the case where a [kΩ] resistor was irradiated with a YAG laser; the resistance value, which was 11 [kΩ] before laser irradiation, decreased to 3.5 [kΩ] after 5 times of irradiation. Furthermore, Fig. 7 shows the sheet resistance value 100 [k
Ω], and the resistance value decreased to 35 [kΩ] after irradiation with the YAG laser four times.

The reduction characteristic of the resistance value of the resistor 25 due to YAG laser irradiation as described above can be changed appropriately by changing the irradiation output, irradiation speed, etc. of the YAG laser, and the resistance value of the resistor 25 can be changed over a wide range. It is possible to reduce the resistance value of. Moreover, the resistance value can be reduced regardless of the film thickness of the resistor 25.

Therefore, by selectively using the process of reducing the resistance value of the resistor 14 by irradiating the resistor 14 with the low-power YAG laser as described above and the trimming process (that is, increasing the resistance value) described above, printing and printing on the insulating substrate 22 can be performed.
Regardless of whether the initial resistance value of the fired resistor 25 is higher or lower than the final resistance value, the resistance value of the resistor 25 can be made to match the final resistance value.
That is, as shown in FIG. 8, if the initial resistance value of the resistor 25 is R ₁ higher than the final resistance value R ₀ , the resistance value is reduced by low-power YAG laser irradiation and the final resistance value is increased. The value R can be brought close to ₀ , and the initial resistance value of the resistor 25 is the final resistance value.
If R ₂ is higher than R ₀ , the resistance value is increased through the trimming process and the final resistance value is
It is possible to approach R ₀ , and the control range for the initial resistance value of the resistor 25 can be made wider than in the past, and the yield can be improved. For example, in order to obtain a desired initial resistance value, it is no longer necessary to strictly define the width and length of the resistor 25 and print it.
This is because it becomes possible to print and form all of the same shape, which greatly simplifies production.

Further, in mass production, the conventional steps such as trial firing of the resistor 14 are no longer necessary, and mass production can be effectively promoted. Furthermore, in order to improve the printing accuracy of the resistor 25, the resistor 25 can be printed at the beginning of the printing process. That is, even if the resistance value of the resistor 25 increases due to the firing process of other parts after the resistor 25 is formed, the resistance value can be decreased later.

Here, the output of the YAG laser mentioned above is required to be of two types, one for reducing the resistance value and one for the trimming process. By controlling the number of irradiations, irradiation speed, irradiation distance, etc. of the high-power YAG laser for the trimming process,
It is also possible to use it for reducing the resistance value. Furthermore, as shown in FIG. 4e, the YAG laser for reducing the resistance value can be used not only to scan the resistor 25 in the horizontal direction in the figure, but also in diagonal and vertical directions. Furthermore, it is also possible to combine horizontal scanning and vertical scanning in a grid-like or crank-like pattern, or to irradiate the entire surface of the resistor 25 at once.

Hereinafter, an embodiment of the present invention based on the above principle will be described in detail with reference to the drawings. FIGS. 9a and 9b show a state in which a multilayer (two layers in the illustrated case) thick film substrate is constructed using a copper-based conductor paste. That is, a ruthenium oxide-based resistance paste is printed on an insulating substrate 28 made of a ceramic material such as alumina, and the paste is heated in the air.
By firing at 850 [℃] for 1 hour, resistor 2
form 9. Next, the lower layer conductor 30 is formed by printing a copper-based conductor paste and baking it at about 850 [° C.] for one hour in a nitrogen gas atmosphere. Furthermore, an insulation layer 31 is formed by printing a glass dielectric insulation paste so as to cover a predetermined portion of the lower conductor 30 and baking it at about 850 [° C.] for one hour in a nitrogen gas atmosphere. After that, the insulating layer 31
A copper-based conductor paste is printed on the lower layer conductor 30 so as to be approximately perpendicular to the lower layer conductor 30, and the paste is approximately perpendicular to the lower layer conductor 30.
By baking at 850[° C.] for one hour, an upper layer conductor 32 is formed, which constitutes a two-layer thick film substrate.

Here, the resistor 29 is first fired in air, and then the lower conductor 30, the insulating layer 31, the upper conductor 32, etc. are fired in a nitrogen gas atmosphere. The resistance value changes significantly from that when fired in air.
By the way, high output and low output as mentioned above
Since the resistance value of the resistor 29 can be increased by YAG laser irradiation, a copper-based conductor paste can be used without any problems.
In addition, since the resistor 29 can be formed by printing first,
It is also possible to improve the printing accuracy of the resistor 29. Further, although a two-layer thick film board has been described above, the copper-based conductive paste can be similarly used for a multilayer thick film board having three or more layers.

Note that FIGS. 10 and 11 show the resistor 2
This shows a flowchart of a laser trimming device and its operation for switching the YAG laser to high output or low output and irradiating the resistor 29 depending on whether the initial resistance value of 9 is lower or higher than the final resistance value. be. First, operate the keyboard 33 to drive and start the arithmetic processing circuit 34 (step
_S1 ). Then, the resistance value of the resistor 29 becomes the probe 3.
5 and bridge circuit 36 (step
S ₂ ), the determination circuit 37 determines whether the final resistance value is lower than a preset final resistance value (step S ₃ ), and the determination result is supplied to the arithmetic processing circuit 34 . If the measured value is lower than the final resistance value (YES), the arithmetic processing circuit 34 sets the current flowing through the pumping lamp 39, such as a krypton lamp, of the laser light source 38 to a high value (that is, corresponding to high laser output). At the same time, the Q switch 40 is operated to oscillate. This laser light source section 38
is the pumping lamp 39 and Q switch 4.
0, it is composed of a YAG rod 41, an aperture 42, mirrors 43, 44, etc.

Then, the YAG rod 41 generates a laser beam of sufficient power to cut the resistor 29 (step S ₄ ). Then, this laser beam is controlled by the X position control mechanism 45 and the Y position control mechanism 46.
The position of the light is controlled in the -Y direction, and the light is focused onto the resistor 29 by the objective lens 47, where laser cutting is performed (step _S5 ). In addition,
The above-mentioned X position control mechanism 45 and Y position control mechanism 46
is controlled by an X-Y drive circuit 49 controlled by an output signal from a control circuit 48 to which the output of the arithmetic processing circuit 34 is supplied, and can move the laser beam in the X-Y direction. .

In this way, the laser-cut resistor 29 is again connected to the probe 35 and the bridge circuit 3.
6, and the determination circuit 37 determines whether the final resistance value has been reached (step S ₆ ). If the final resistance value has not been reached (NO), the arithmetic processing circuit 34 performs the process of step _S2 again; if the final resistance value has been reached (YES), the arithmetic processing circuit 34 34 controls the control circuit 48 to stop the movement of the laser beam in the X-Y direction, and
A mechanical shutter (not shown) is interposed between the objective lens 47 and the resistor 29 to prevent the YAG laser from irradiating the resistor 29, and the laser cutting is completed here (step
_S7 ).

On the other hand, if the measured value is higher than the final resistance value (NO) in step _S3 , the arithmetic processing circuit 34
The current flowing through the pumping lamp 39 is set to a low value (that is, corresponding to low laser output), and the Q switch 40 is operated to oscillate. Then,
A low-power laser beam is generated from the YAG rod 41 (step S ₈ ), and the laser beam is
The light is focused on the resistor 29 and scanned through the X position control mechanism 45, the Y position control mechanism 46, and the objective lens 47, and the resistance value is decreased there (step _S9 ).

In this way, the resistance value of the resistor 2 is reduced.
9, the resistance value is measured again by the probe 35 and the bridge circuit 36, and the determination circuit 36 determines whether the final resistance value has been reached (step
_S10 ). If the final resistance value has not been reached (NO), the arithmetic processing circuit 34 steps again.
When the process of _S2 is started and the final resistance value is reached (YES), the process proceeds to step _S7 , that is, the laser beam is blocked by a shutter and the X-Y
directional movement is stopped.

Therefore, by using the laser trimming device as described above, the resistance value of the resistor 29 can be increased or decreased to easily obtain the final resistance value.

Here, the laser trimming device measures the resistance value of the resistor 29, and based on this measurement result,
Although the description has been given of a device that automatically switches the YAG laser between high and low outputs, the present invention is not limited to this, and the user can manually switch the YAG laser between high and low outputs based on the resistance measurement results. Of course it's a good thing. Further, the laser beam is not limited to a YAG laser.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without departing from the gist thereof.

〔Effect of the invention〕

Therefore, as detailed above, according to the present invention, it is possible to easily increase or decrease the resistance value of a resistor to form a resistor having a final resistance value,
It is possible to provide an extremely good method for manufacturing a multilayer thick film substrate that can effectively promote mass production.

[Brief explanation of the drawing]

Figure 1 is a plan view for explaining the manufacturing method of a film resistor, Figure 2 is a characteristic curve diagram for explaining the trimming process of the same manufacturing method, and Figure 3 is a conventional method for manufacturing a multilayer thick film substrate. FIG. 4 is a plan view for explaining the principle of this invention, and FIG.
7 to 7 are characteristic curve diagrams showing the number of laser irradiations and changes in the resistance value of the resistor based on the same principle, FIG. 8 is a diagram for explaining the resistance value correction means based on the same principle, and FIG. 9 10 is a diagram showing an embodiment of the method for manufacturing a multilayer thick film substrate according to the present invention, and FIGS. 10 and 11 are block diagrams showing a laser trimming device of the same embodiment and a flowchart for explaining its operation, respectively. It's a chat. 11... Insulating substrate, 12, 13... Wiring conductor layer, 14... Resistor, 17... Insulating substrate, 18...
... lower layer conductor, 19 ... insulating layer, 20 ... resistor,
21... Upper layer conductor, 22... Insulating substrate, 23,2
4...Wiring conductor layer, 25...Resistor, 28...Insulating substrate, 29...Resistor, 30...Lower conductor, 3
DESCRIPTION OF SYMBOLS 1... Insulating layer, 32... Upper layer conductor, 33... Keyboard, 34... Arithmetic processing circuit, 35... Prologue, 36... Bridge circuit, 37... Judgment circuit,
38...Laser light source section, 39...Pumping lamp, 40...Q switch, 41...YAG rod,
42...Aperture, 43,44...Mirror, 45...
...X position control mechanism, 46...Y position control mechanism, 4
7... Objective lens, 48... Control circuit, 49...
X-Y drive circuit.

Claims (1)

[Claims] 1. A first step of printing a resistor paste on an insulating substrate and baking it in air to form a resistor; and after this first step, applying a conductive paste and an insulating paste to the insulating substrate. A second step of printing and baking to form a conductor layer and an insulating layer, and after this second step, the resistor is irradiated with a low-power laser beam that does not scatter the conductive particles and glass components in the resistor. A first treatment step of irradiating the resistor to reduce the resistance value of the resistor; 1. A method for manufacturing a multilayer thick film substrate, comprising: a second treatment step for increasing the resistance value of the substrate; and a third step for selectively performing the treatment step. 2. The method of manufacturing a multilayer thick film substrate according to claim 1, wherein the conductor layer is formed by firing a copper-based conductor paste in a nitrogen gas atmosphere.