JP2003289001A - Thick film electronic part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems that the lowering of the resistance of a thermistor and the reduction of fluctuations of characteristics are obstructed since a glass component contained in a thermistor layer has an unfavourable effect on a thermistor characteristic (resistivity B constant), and that a void is caused by a glass frit, so that moisture resistance is deteriorated and the reliability of a product suffers from a unfavourable influence. <P>SOLUTION: At least a single pair of internal electrodes and a thick film function layer are connected with each other to form a thick functioning layer on an insulation substrate. A thick film electronic part comprises the thick functioning layer and a pair of end electrodes connected to the single pair of internal electrodes, respectively. The single pair of internal electrodes and the thick film functioning layer are formed sandwiching an adhesive layer of almost the same component as the thick film functioning layer therebetween on the insulation substrate. <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 thick film type electronic component having a functional film printed thereon.

[0002]

2. Description of the Related Art As a conventional method for producing an electronic component, for example, a chip type NTC thermistor element having a negative temperature coefficient, glass frit is added to the thermistor powder to form a paste, which is then screen-printed onto alumina. A method of coating on a substrate and baking at a low temperature (700 to 1000 ° C.) is known. NTC thermistor is 1000
Unless it is fired at ˜1400 ° C., the base material will not be dense and the thermistor characteristics originally required cannot be obtained. Therefore,
By adding glass frit as a sintering aid, sintering at low temperature (700 to 1000 ° C.) is possible. Further, the addition of glass frit ensures the close contact with the alumina substrate.

[0003]

However, the glass component contained in the thermistor layer acts as an impurity and adversely affects the thermistor characteristics (resistivity B constant), which lowers the resistance of the thermistor element and narrows the characteristic deviation. It was hindered. In addition, voids such as voids are generated by the glass frit and the moisture resistance is reduced, which adversely affects the reliability of the product.

[0004]

The present invention connects at least a pair of internal electrodes formed on an insulating substrate, a thick film functional layer formed between a pair of internal electrodes, and a pair of internal electrodes. A thick film type electronic component having a pair of end electrodes, wherein a pair of internal electrodes and a thick film functional layer are provided on an insulating substrate via an adhesion layer having substantially the same components as the thick film functional layer. It is a thick film electronic component characterized by being formed.

A thick-film electronic component is provided with a protective layer having substantially the same composition as that of the thick-film functional layer, which covers a layer composed of a pair of internal electrodes and the thick-film functional layer. A thick-film electronic component having a structure in which the thick-film functional layer has a characteristic that its electric resistance changes according to temperature. It is a thick film electronic component in which the thick film functional layer does not contain glass frit.

A step of printing a pattern of the adhesion layer on the insulating substrate using a paste having substantially the same composition as that of the thick film functional layer, and a pattern of the thick film functional layer and the internal electrode layer on the pattern of the adhesion layer. A method of manufacturing a thick film electronic component, comprising: a step of printing each of them; and a step of simultaneously firing the patterns of the adhesion layer, the thick film functional layer, and the internal electrodes at a predetermined temperature. Specified temperature from 1000 ℃ to 14
This is a method of manufacturing a thick film electronic component having a configuration of 00 ° C.

[0007]

1 is a structural example of a chip-type thick film thermistor element 1 according to an embodiment of the present invention. The thick film thermistor element 1 includes an adhesion layer 3 formed on an alumina substrate 2 which is an insulating substrate, and a first adhesion layer 3 formed on the adhesion layer 3.
1 Internal electrode 4a and the thermistor layer 5 which is a functional layer formed on the first internal electrode 4a to obtain thermistor characteristics
And the second internal electrode 4b formed on the thermistor layer 5.
And a first protective layer 7 formed on the second internal electrode 4b,
The second protective layer 8 is formed on the first protective layer 7, and the end electrodes 9a and 9b are connected to the first internal electrode 4a and the second internal electrode 4b, respectively.

The alumina substrate 2 is an insulating substrate containing Al ₂ O ₃ as its main component. The first internal electrode 4a and the second internal electrode 4b use a paste containing Ag / Pd or Pd as a main component. The adhesion layer 3, the thermistor layer 5, and the first protective layer 7 are formed of a paste of the same material having a characteristic that electric resistance changes according to temperature change,
It is a material having a negative temperature characteristic mainly composed of transition metal components such as Mn, Ni, Co and Fe. Although the adhesion layer 3, the thermistor layer 5 and the first protective layer 7 are made of the same material, it is the thermistor layer 5 sandwiched between the first internal electrode 4a and the second internal electrode 4b that actually exhibits thermistor characteristics. Therefore, the characteristics of the adhesion layer 3 and the first protective layer 7 are not affected. The second protective layer 8 is made of a paste using borosilicate glass, an epoxy resin, or a polyimide resin. The end electrodes 9a and 9b have a three-layer structure including a base electrode of silver or nichrome, nickel plating, and solder plating.

FIG. 2 shows another embodiment of the present invention. It should be noted that the description of the components having the same reference numerals as those in FIG. 1 will be omitted. FIG. 2A shows a configuration in which the thermistor layer 5 is provided with the single-layer internal electrodes 4c and 4d. FIG. 2B shows a configuration in which the internal electrodes 4e, 4f, 4g are arranged so as to partially overlap each other. The internal electrode 4f is formed between the thermistor layers 5a and 5b which are functional layers. FIG. 2C shows a configuration in which the internal electrodes are provided above and below the thermistor layer 5, and the internal electrodes 4h and 4j and the internal electrodes 4i and 4k are arranged to face each other. In FIG. 2D, the internal electrodes are provided above and below the thermistor layer 5 in between,
1, 4n and the internal electrodes 4m, 4q are arranged so as to face each other, and the internal electrode 4p is arranged so as to partially overlap with them. Each of these embodiments may be appropriately selected according to the characteristics required for the thermistor element.

3 and 4 show a method of manufacturing the thick film thermistor element according to the present invention, particularly a method of manufacturing the thick film thermistor element 1 shown in FIG. FIG. 3A shows a state in which the adhesion layer pattern 15a is printed with a thermistor paste to form the adhesion layer 3 on the multi-cavity alumina substrate 2 in which the substrate dividing grooves 11 and 12 are formed vertically and horizontally. Show. The alumina substrate 2 is an insulating substrate whose main component is Al ₂ O ₃ .

Here, the adhesion layer 3 and the thermistor described later
Thermistor sheet used for forming the star layer 5 and the first protective layer 7.
A method of creating a strike will be described. First, the thermistor
The ratio is Mn: 30-60mol%, Ni: 10-30
mol%, Co: 10 to 30 mol%, Fe: 10 to 3
Using 0 mol% of various metal oxides as a raw material and a solvent
Then, by a wet ball mill using water or alcohol
Mix to form a slurry. Gold used as a starting material
As the group oxide, Mn_ThreeO_Four, NiO, Co _ThreeO_Four，
Fe_TwoO_Threeand so on. Dry the mixed slurry with water
After removing minutes and alcohol,
And calcination. Wet ball mill for pre-baked powder
Crush by. At this time, the solvent is water or alcohol
There is. The resulting slurry is dried to remove water or alcohol.
After removing the component, ethyl cellulose, α-terpine
Thermistor pace by adding all and using a 3-roll mill
Create Thermistor pace created in this way
The glass does not contain glass frit. In addition, the above
Besides, Mn / Ni / Co system, Mn / Ni / Co / Cu
System, Mn / Co / Al system, Mn / Ni / Co / Al system,
Mn / Co / Cu system, Mn / Ni / Fe system, Mn / Ni
/ Fe / Al system, Ma / Ni / Fe / Cu system, Mn / C
Even if selected or combined from o / Al / Cu system, etc.
Good. Also, the component ratio can be arbitrarily determined according to the characteristics.
Good.

After applying the adhesion layer pattern 15a to the alumina substrate 2 by screen printing, as shown in FIG. 3B, the internal electrode pattern 16a is applied by conductive printing to form the internal electrode 4a. . The conductive paste is a paste containing Ag / Pd or Pd as a main component. Next, as shown in FIG. 3C, in order to form the thermistor layer 5 which is a functional film, the thermistor layer pattern 15b is applied by screen printing with a thermistor paste. Next, as shown in FIG. 3D, in order to form the internal electrode 4b, the internal electrode pattern 16b is applied by screen printing with a conductive paste containing Ag / Pd or Pd as a main component. Next, as shown in FIG. 3E, in order to form the first protective layer 7, the first protective layer pattern 15c is applied by screen printing with a thermistor paste.

Then, the adhesion layer pattern 15a and the internal electrode pattern 16 are screen-printed on the alumina substrate 2.
a, the thermistor layer pattern 15b, internal electrode pattern 1
6b and the first protective layer pattern 15c are simultaneously fired. The firing temperature is 1000 ° C to 1400 ° C. Since the adhesion layer pattern 15a causes a solid phase reaction with the alumina substrate 2 by firing at 900 ° C. or higher,
By firing at a temperature of 1 ° C to 1400 ° C, the adhesion layer 3 and the alumina substrate 2 are firmly adhered. In addition, the adhesion layer pattern 15
Since the a, the thermistor layer pattern 15b, and the first protective layer pattern 15c have the same component, the adhesion layer 3, the thermistor layer 5, and the first protective layer 7 formed by them firmly adhere to each other. . Furthermore, 1000 ℃ ~ 1
Since it is fired at 400 ° C., the base material of the thermistor layer 5 becomes dense, and it is possible to reduce the resistance, narrow the characteristic deviation, and prevent the reliability from decreasing.

Although the alumina substrate 2 and the adhesion layer 3 are firmly adhered to each other, the alumina substrate 2 and the thermistor paste have different contraction rates when fired, and therefore the adhesion surface is finely bonded to the adhesion layer 3. Cracks occur. However, since the adhesion layer 3 is interposed between the thermistor layer 5 and the alumina substrate 2 which contribute to the thermistor characteristics, the adhesion layer 3 absorbs the inconsistency in shrinkage ratio between the alumina substrate 2 and the thermistor layer 5. . Therefore, although the adhesive layer 3 that does not affect the thermistor characteristics is cracked,
The thermistor layer 5 does not have defects such as cracks, and does not affect the characteristics of the manufactured thick film thermistor element 1. In this way, in order for the adhesion layer 3 to mitigate the mismatch in shrinkage between the alumina substrate 2 and the thermistor layer 3, the adhesion layer 3 preferably has a thickness of at least about 20 to 30 μm.

Further, the first protective layer 7 which is firmly adhered to the thermistor layer 5 and has a dense base material by firing at a high temperature.
Since the above-mentioned structure is formed, it is possible to effectively prevent migration and the like, and suppress deterioration of product reliability due to moisture.

Next, as shown in FIG. 3F, a paste using borosilicate glass or a protective paste made of an epoxy-based or polyimide-based resin is applied and then cured by heating to form a second protective layer. 8 is formed. Next, the alumina substrate 2 is divided into strips along the dividing grooves 12, and Ag or Ag is attached to the end face of the strip-shaped alumina substrate 2 as shown in FIG.
The terminal electrodes 17a and 17b are formed by coating or dipping using a / Pd paste, or by sputtering or vapor deposition using a metal material such as nichrome. Next, as shown in FIG. 4B, the alumina substrate 2 is divided into individual pieces along the division groove 11, and a nickel plating layer and a solder plating layer are formed on the terminal electrodes 17a and 17b by electrolytic plating. The partial electrodes 9a and 9b are formed.

Through the above manufacturing steps, the chip size is 1.0 mm × 0.5 mm × 0.5 mm, the resistance value at 25 ° C. is R25 = 10 kΩ, and the B constant is B25 / 85 = 3435.
A kC NTC thick film thermistor device was obtained. The chip size and others can be changed as appropriate.

FIG. 5 is a histogram of the conventional product (having a thermistor layer containing glass frit) and the product of the present invention with respect to characteristic deviation. 2 for 100 samples
Fig. 5 shows the variation in resistance value at 5 ° C.
5A shows the conventional product, and FIG. 5B shows the product of the present invention. Figure 5
In the conventional product shown in (a), the characteristic distribution is wide as shown, but in the product of the present invention shown in FIG. 5 (a), the variation is extremely reduced. Comparing with the numerical value showing the deviation (standard deviation (σ) multiplied by 3 and divided by its average value multiplied by 100), the deviation in resistance value at 25 ° C is 6.1 for the conventional product. Inventive product 1.3
And the product of the present invention is remarkably improved.

FIG. 6 shows histograms of the B constant of the conventional product (having a thermistor layer containing glass frit) and the product of the present invention. 6 (a) is a conventional product, FIG. 6 (b)
Indicates the product of the present invention. Here again, the characteristic distribution of the product of the present invention is narrower than that of the conventional product. Numerical value indicating the deviation (standard deviation
The value obtained by multiplying (σ) by 3 and dividing by the average value and multiplying by 100) is compared, and the deviation of the B constant is 1.
0, 0.3 for the product of the present invention and significantly improved for the product of the present invention.

FIG. 7 shows a 200 ° C. constant temperature storage test (1000
Fig. 7 (a) shows the change in characteristics at 0 hour).
Shows the variation of the resistance value (ΔR25), and FIG. 7B shows the variation of the B constant. The vertical axis represents the rate of change and the horizontal axis represents the time axis. Further, the polygonal line indicated by ◯ is a conventional product (having a thermistor layer containing glass frit), and the polygonal line indicated by Δ is the product of the present invention. As is apparent from these graphs, the product of the present invention has significantly improved reliability as compared with the conventional product.

FIG. 8 shows a moisture resistance load test (10000 hours).
8A shows the change in the characteristics, FIG. 8A shows the fluctuation of the resistance value (ΔR25), and FIG. 8B shows the fluctuation of the B constant. The vertical axis represents the rate of change and the horizontal axis represents the time axis. Further, the polygonal line indicated by ◯ is a conventional product (having a thermistor layer containing glass frit), and the polygonal line indicated by Δ is the product of the present invention. As is clear from these graphs, in the product of the present invention, in comparison with the conventional product,
It can be seen that the reliability is remarkably improved. The humidity resistance load test was conducted under the conditions of 60 ° C., 95% RH, and DC5V applied.

As described above, in the thermistor element of the present invention, since the thermistor layer does not contain impurities such as glass frit and is fired at the optimum firing temperature, an extremely dense layer is formed, which results in the above It is considered that the narrow deviation of the characteristics of and the high reliability are achieved. Further, the structure of the chip type thermistor element of the present invention is
Since it has a structure in which a thermistor layer and an electrode are laminated on an alumina substrate by a printing method, an NTC thermistor element having a high B constant and a low resistance value like a chip type laminated thermistor manufactured by a green sheet method. Can be obtained.

The chip type laminated thermistor manufactured by the green sheet method has a complicated manufacturing process as compared with the present invention. Further, when the thermistor paste and the electrode paste are respectively printed by screen printing and laminated, since the base substrate is a green sheet, it is different from the alumina substrate of the present invention, and is a thermally stable and strong substance. is not. Therefore, when the printing is performed, the printing base is deformed, which impedes the printing accuracy, causes a deviation in the resistance value, lowers the product yield, and tends to increase the product cost. On the other hand, in the manufacturing process of the present invention, since the thermistor layer and the electrode layer are laminated by the printing method, the laminated structure can be obtained with a relatively simple process with high accuracy.

The paste used for the adhesion layer 3 may contain glass frit, alumina powder or the like. The present invention can also be applied to chip capacitors and chip varistors.

[0025]

According to the present invention, it is possible to realize an electronic component having a low resistance, a narrow deviation of characteristics and high reliability at a low manufacturing cost.

[Brief description of drawings]

FIG. 1 shows a structure of a chip type thick film thermistor element according to an embodiment of the present invention.

FIG. 2 shows a structure of a chip-type thick film thermistor element which is another embodiment of the present invention.

FIG. 3 shows a manufacturing process of a chip type thick film thermistor element.

FIG. 4 shows a manufacturing process of a chip type thick film thermistor element.

FIG. 5 is a graph showing the characteristic deviation of the resistance value,
(B) Histograms showing respective examples of the present invention.

FIG. 6 shows a characteristic deviation of the B constant from (a) a conventional example,
(B) Histograms showing respective examples of the present invention.

FIG. 7 shows (a) changes in resistance value in a constant temperature test,
(B) A graph comparing the conventional example and the present invention with respect to changes in the B constant.

FIG. 8 shows (a) a change in resistance value in a humidity resistance load test,
(B) A graph comparing the conventional example and the present invention with respect to changes in the B constant.

[Explanation of symbols]

1 Thick film thermistor element 2 Alumina substrate 2 3 Adhesion layer 4a 1st internal electrode 4b Second internal electrode 5 Thermistor layer 5 7 First protective layer 7 8 Second protective layer 8 9a Edge electrode 9b End electrode

Claims (6)

[Claims] 1. At least a pair of internal electrodes formed on an insulating substrate, a thick film functional layer formed between a pair of internal electrodes, and a pair of end electrodes respectively connected to the pair of internal electrodes. A thick-film electronic component, characterized in that a pair of internal electrodes and a thick-film functional layer are formed on an insulating substrate via an adhesion layer having substantially the same composition as the thick-film functional layer. Membrane electronic components. 2. The thick film electron according to claim 1, wherein a protective layer having substantially the same composition as that of the thick film functional layer is formed to cover a layer composed of a pair of internal electrodes and the thick film functional layer. parts. 3. The thick film electronic component according to claim 1, wherein the thick film functional layer has a characteristic that electric resistance changes according to temperature change. 4. The thick film electronic component according to claim 1, wherein the thick film functional layer contains no glass frit. 5. A step of printing a pattern of an adhesion layer on an insulating substrate using a paste having substantially the same composition as that of the thick film functional layer, and a step of forming the thick film functional layer and the internal electrode layer on the pattern of the adhesion layer. A method of manufacturing a thick film electronic component, comprising: a step of printing each pattern; and a step of simultaneously firing the patterns of the adhesion layer, the thick film functional layer and the internal electrodes at a predetermined temperature. 6. The predetermined temperature is 1000 ° C. to 1400 ° C.
The method for manufacturing a thick film electronic component according to claim 5, wherein