KR20190081172A - sensor element of ceramic type particulate matter sensor and method for manufacturing of the sensor - Google Patents

Abstract

The present invention relates to a sensor element of a ceramic particulate matter sensor and a manufacturing method thereof to generate a sensor output from the initial deposition of particulate matter on the surface of the sensor, thereby improving the response speed and increasing the output when particulate matter is detected. The sensor element of a ceramic particulate matter sensor according to the present invention includes a plurality of reference electrodes (122, 123) having a line shape of a conductive material on the surface of a substrate (121) and patterned to be spaced apart from each other, deposits particulate matter (PM) included in exhaust gas of an engine between the spaced reference electrodes (122, 123) to electrically connect the spaced reference electrodes (122, 123) to each other, and detects the particulate matter (PM) contained in the exhaust gas. Island electrodes (125) in a spot form are formed to be spaced apart from each other between the reference electrodes (122, 123) spaced apart from each other on the surface of the substrate (121). When the particulate matter (PM) is deposited on the substrate (121), the reference electrodes (122, 123) are electrically connected to each other by the particulate matter (PM) and the island electrode (125).

Description

Technical Field [0001] The present invention relates to a sensor element of a ceramic particulate matter sensor and a manufacturing method thereof,

The present invention relates to a ceramic particulate matter sensor for detecting particulate matter contained in exhaust gas of an engine, and more particularly to a ceramic particulate matter sensor for detecting particulate matter contained in exhaust gas of an engine, A sensor element of a ceramic particulate matter sensor and a method of manufacturing the same.

Various kinds of harmful substances are included in the exhaust gas of the vehicle, and these harmful substances are reduced from the combustion stage, or only a minimal amount is discharged after being purified in the exhaust system.

As described above, in order to reduce the exhaust gas, a sensor capable of measuring the harmful substances included in the exhaust gas is mounted on the exhaust line.

1, a particulate matter sensor for detecting particulate matter (PM) contained in the exhaust gas is installed.

The particulate matter sensor 10 includes a coupling part 11 fastened to an exhaust line, an outer housing 12 forming an outer shape of the particulate matter sensor 10, A sleeve 14 on which the sensor element 20 is installed and a sensor element 20 for sensing the particulate matter in the flowing liquid on the exhaust line when the particulate matter is deposited.

As shown in FIG. 2, the sensor element 20 is formed by printing an electrode on a substrate 21 in a pattern. Since the particulate matter sensor 10 is exposed to the exhaust gas at a high temperature, the substrate 21 is typically formed of a ceramic material and the platinum is patterned on the substrate 21.

The particulate matter sensor 10 senses particulate matter contained in the exhaust gas to allow a user to recognize a failure such as a crack of a DPF (Diesel Particulate Filter). When an abnormality occurs in the post-treatment apparatus such as the DPF or the like, the post-treatment apparatus is not normally operated and a larger amount of particulate matter is discharged than in a usual case, thereby detecting a failure of the post-treatment apparatus such as the DPF .

The particulate matter sensor 10 may be classified into a resistance method and a capacitance method according to a particulate matter detection method.

3 and 4 show the sensor element 20A applied to the particulate matter sensor 10 of the resistance type.

The sensor element 20A applied to the resistance type particulate matter sensor 10 has the electrodes 22 and 23 formed on the inside and the surface of the substrate 21, A heater 24 for activating the sensor 10 is formed. Electrodes 22 and 23 are patterned on the surface of the substrate 21 and the adjacent electrodes 22 and 23 are not electrically connected to each other. When the particulate matter PM is deposited, the electrodes 22 and 23 spaced from each other are electrically connected to each other by the particulate matter PM, and the particulate matter PM acts as a resistor, And detects the particulate matter PM by a change in current.

The sensor element 20A applied to the particulate matter sensor 10 of the resistive type did not detect the particulate matter PM until the electrodes 22 and 23 on the surfaces separated from each other were connected to each other.

5 and 6 show the sensor element 20B applied to the particulate matter sensor 10 of the capacitive type.

Electrodes 22 and 23 are formed on the upper and lower surfaces of the substrate 21 on which the dielectric is formed. In this case, the electrodes 22 formed on the surface exposed to the exhaust gas are patterned to be spaced apart from each other. Until the particulate matter (PM) is deposited, a correcting capacitance is generated in proportion to the area of the patterned portion of the electrode (22). When the particulate matter PM is deposited, the spaced apart electrodes 22 are connected to each other, so that the area of the electrode 22 on the surface exposed to the exhaust gas is widened. Thus, when the area of the electrode 22 is enlarged due to deposition of the particulate matter PM, the amount of the particulate matter PM is detected by using the increased amount of the correction capacity.

The sensor element 20B applied to the particulate matter sensor 10 of the capacitance type can not detect the particulate matter PM until the electrodes 22 separated from each other are connected to each other.

In order to improve the response speed in the resistance type particulate matter sensor 10 and the sensor elements 20A and 20B applied to the capacitance type particulate matter sensor 10, It is necessary to increase the area increase rate of the electrode by minimizing the interval of the electrodes so that the spaced electrodes are connected to each other. However, the limit of the printing process is limited to less than about 20 μm.

On the other hand, the following prior art reference discloses a technique related to a 'particulate matter sensor'.

KR 10-1401713 B1

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a ceramic particulate material capable of improving the response speed and the output value by allowing the electrodes patterned to be spaced apart from each other on the surface of the substrate to be connected to each other at the beginning of deposition of particulate matter And to provide a sensor element and a method of manufacturing the same.

According to an aspect of the present invention, there is provided a sensor device for a ceramic particulate matter sensor including a plurality of reference electrodes patterned on a surface of a substrate in a line form with a conductive material, 1. A sensor for a particulate matter sensor for detecting particulate matter contained in an exhaust gas by depositing particulate matter contained in exhaust gas of an engine between electrodes and electrically connecting the separated reference electrodes to each other, The island electrodes formed in a spot shape are spaced apart from each other with a space therebetween, and when the particulate matter is deposited on the substrate, the reference electrode is separated from the particulate matter and the island electrode Wherein the ceramic particulate matter sensor is electrically connected to the ceramic particulate matter sensor Of the sensor element.

And the total area of the island electrodes is formed at a predetermined ratio with respect to an area between the reference electrodes spaced apart from each other.

And the total area of the island electrodes is formed to be 5% or more and 65% or less of the area between the reference electrodes which are spaced apart from each other.

And the total area of the island electrodes is 30% or more and 65% or less of the area between the reference electrodes spaced apart from each other.

And the island electrode is formed by screen printing.

And the island electrode is formed of the same material as the reference electrode.

And the island electrode is made of platinum.

And the total weight of the island electrodes is 30 wt% to 65 wt% of the total weight of the reference electrode.

An auxiliary electrode patterned along the direction in which the reference electrode is formed and not electrically connected to the reference electrode is formed between the reference electrodes spaced apart from each other, and the island electrodes are formed between the reference electrode and the auxiliary electrode .

And the total area of the island electrodes is formed at a predetermined ratio with respect to the area between the reference electrodes.

And the island electrode, the reference electrode, and the heater are formed of the same material.

And the sensor element of the particulate matter is applied to a particulate matter sensor of a capacitance type.

Wherein the sensor element of the particulate matter is applied to a particulate matter sensor of a resistance type.

Meanwhile, a method of manufacturing a sensor element of a ceramic particulate matter sensor according to the present invention includes a mask preparation step of raising a mask patterned with a pattern including an island electrode on a substrate, an electrode paste application step of applying an electrode paste to a substrate by screen printing, And an electrode sintering step of sintering the electrode paste.

In the mask preparation step, the patterned mask is placed on the alumina substrate.

And a preheating step of preheating the electrode paste by dry fixing between the electrode paste applying step and the electrode sintering step.

In the mask preparation step, a patterned mask is placed on alumina green paper.

According to the sensor element of the ceramic particulate matter sensor of the present invention having the above structure and the method of manufacturing the same, the dot-shaped island electrode is previously patterned between the first electrode and the second electrode patterned on the surface of the substrate, The electrodes are connected to each other at the initial stage of the deposition of the particulate matter, thereby improving the response speed.

Particularly, when the present invention is applied to a particulate matter sensor of a capacitance type, the electrostatic capacity is improved as the electrode surface is increased by the island electrode, and the output value of the sensor can be improved.

1 is a sectional view showing a conventional particulate matter sensor;
2 is a plan view showing a sensor element of a particulate matter sensor according to the prior art;
3 is a cross-sectional view showing a sensor element of a resistive particulate matter sensor according to the prior art.
4 is a cross-sectional view showing the operation principle of a sensor element of a resistance type particulate matter sensor according to the related art.
5 is a cross-sectional view showing a sensor element of a capacitive-type particulate matter sensor according to the related art.
6 is a cross-sectional view showing the operation principle of a sensor element of a capacitive-type particulate matter sensor according to the related art.
7 is a plan view showing a sensor element of a ceramic particulate matter sensor according to the present invention.
FIG. 8 is an enlarged view showing a state in which particulate matter is deposited in a sensor element of a ceramic particulate matter sensor according to the present invention. FIG.
9A to 9D are electron micrographs according to the area ratio of the island electrode in the sensor element of the ceramic particulate matter sensor according to the present invention. FIG. 9A shows the area ratio of the island electrode is 5%, FIG. 9B shows the area ratio of the island electrode is 10% FIG. 9c is an electron micrograph of an island electrode area ratio of 30%, and FIG. 9d is an island electrode area ratio of 60%.
10 is a flowchart showing a method of manufacturing a sensor element of a ceramic particulate matter sensor according to the present invention.

Hereinafter, the sensor element of the ceramic particulate matter sensor according to the present invention will be described in detail with reference to the accompanying drawings.

The sensor element of the ceramic particulate matter sensor according to the present invention includes a plurality of reference electrodes 122 and 123 that are patterned in a line form with a conductive material on a surface of a substrate 121 so as to be spaced apart from each other, Particulate matter (PM) contained in the exhaust gas of the engine is deposited between the reference electrodes 122 and 123 to electrically connect the reference electrodes 122 and 123 spaced apart from each other so that the particulate matter contained in the exhaust gas The island electrodes 125 formed in a spot shape are formed between the reference electrodes 122 and 123 spaced from each other on the surface of the substrate 121 in the sensor element of the particulate matter sensor that detects the PM The reference electrode 122 and the reference electrode 122 are separated from each other by the particulate matter PM and the island electrode 125 when the particulate matter PM is deposited on the substrate 121. [ And are electrically connected to each other.

The substrate 121 is made of an insulator. The substrate 121 is formed in a planar shape, and more specifically, in conformity with the mounting position of the particulate matter sensor 10. [ The substrate 121 also serves as a dielectric when the sensor element 120 is applied to the particulate matter sensor 10 of the correction capacitance type. The substrate 121 may be a ceramic substrate made of alumina (Al ₂ O ₃ ) having excellent mechanical strength and high temperature characteristics because the sensor element 120 is exposed to a high temperature exhaust gas.

The reference electrodes 122 and 123 are patterned on the substrate 121 with a conductive material. The reference electrodes 122 and 123 are preferably formed in the form of a line, preferably a straight line. The reference electrodes 122 and 123 are preferably formed on the surface of the substrate 121 exposed to the exhaust gas. Since the reference electrodes 122 and 123 are spaced apart from the adjacent reference electrodes 122 and 123 and sense the deposition of the particulate matter PM between the spaced apart intervals, As shown in Fig.

The substrate 121 may also be provided with a heater 124 for heating the particulate matter sensor 10 to which the sensor element 120 is applied. 7, the heater 124 may be patterned in the space between the reference electrodes 122 and 123 on the substrate 121 or may be patterned in the substrate 121 .

The island electrodes 125 are formed on the substrate 121 between the reference electrodes 122 and 123. The island electrode 125 may be formed in a spot shape and may not be connected to the adjacent island electrodes 125 or the reference electrodes 122 and 123.

The island electrode 125 may be made of the same material as the reference electrodes 122 and 123, for example, platinum (Pt) having excellent chemical resistance.

The island electrode 125 may be formed in the same manner as the reference electrodes 122 and 123 when the reference electrodes 122 and 123 are patterned, for example, by screen printing. For example, the island electrode 125 is formed by screen printing with a mesh type mask positioned on the upper surface of the substrate 121.

Since the island electrodes 125 are formed between the reference electrodes 122 and 123 with a predetermined gap on the substrate 121, the particulate matter PM and the island- The island electrodes 125 are connected to each other to bridge the reference electrodes 122 and 123 spaced apart from each other, so that the reaction speed and the sensor output are improved.

At this time, the island electrodes 125 may be formed at a predetermined ratio with respect to the area between the reference electrodes 122 and 123. That is, the ratio of the sum of the areas of the island electrodes 125 formed therebetween with respect to the area between the reference electrodes 122 and 123 can be referred to as the density of the island electrodes, and the density of the island electrodes . For example, if the density of the island electrode is 30%, it means that the total area of the island electrodes 125 is 30% with respect to the area between the reference electrodes 122 and 123.

The density of the island electrode is preferably 5% or more and 65% or more, more preferably 30% or more and 65% or less. If the density of the island electrode exceeds 65%, the island electrode 125 may be connected to the adjacent island electrode 125 or the reference electrode 122 or 123.

It is preferable that the island electrode 125 is formed on the substrate in an amount of 30 wt% to 65 wt% with respect to the weight of the reference electrode 122 and 123.

However, it is preferable that the island electrode 125 is not formed outside the reference electrode 122 (123) formed at the outermost portion of the substrate 121. Even when the particulate matter PM is deposited outside the reference electrodes 122 and 123 formed at the outermost portion of the substrate 121, no bridges are formed with the other reference electrodes 122 and 123. Therefore, The island electrodes 125 are not formed on the outside of the reference electrodes 122 and 123.

The island electrodes 125 are preferably uniformly distributed on the substrate 121. In other words, the island electrode 125 is formed with the density, i.e., the area ratio, as described above, and the distance between the island electrode 125 and the adjacent island electrode 125 is maximized, Is not significantly lower than the other regions.

The heater 124 is formed on the substrate 121 and serves to heat the sensor element 120 to quickly reach the activation temperature.

7 shows a structure in which the first reference electrode 122 and the second reference electrode 123 are formed on the substrate 121 and the heater 124 is formed.

8 shows a state in which particulate matter PM is deposited. The particulate matter PM is deposited between two electrodes, for example, between the first reference electrode 122 and the second reference electrode 123, A bridge is formed by the particulate matter PM and the island electrode 125 so that the response speed is lower than that of the sensor element 120 in which the island electrode 125 is not formed It accelerates. In addition, the area of the electrode is also increased, so that the output value is also improved.

The sensor element 120 of the particulate matter sensor having the above configuration can be applied to the particulate matter sensor 10 of the resistance type or to the particulate matter sensor 10 of the capacitive type.

Hereinafter, each embodiment of the sensor element 120 of the particulate matter sensor according to the present invention will be described.

In the following table, the sensor element 120 is manufactured according to the density of the island electrode up to the density of the island electrode of 5% to 65%, and then applied to the particulate matter sensor 10 of the corrected capacity type to measure the response speed and output performance An evaluation example is shown.

The concentration of the particulate matter contained in the exhaust gas was 10 to 15 mg / m ³ , the flow rate of the exhaust gas was 70 kg / h, and the temperature of the exhaust gas was 300 ° C.

Island electrode density Initial value (pF) After 15 minutes (pF) Output variation Response time Comparative Example - 53.8 58.1 4.3 2300 s Example 1 5% 54.2 59.1 4.9 2200 s Example 2 10% 55.7 94.4 38.7 1700 s Example 3 25% 55.8 95.1 39.3 1700 s Example 4 30% 56.1 107.9 51.8 1200 s Example 5 60% 62.7 115.5 62.1 1100 s Example 6 65% 63.1 117.2 54.1 1300 s Example 7 70% - - - -

First, according to Example 1, in which the density of the island electrode is 5%, the output of the particulate matter sensor is improved by 4.9 pF and the response time is reduced by 100 s as compared with the prior art (comparative example in the case where there is no island electrode) .

The density of the island electrode 125 was increased to 10% (Example 2), 25% (Example 3), 30% (Example 4), 60% (Example 5) In this case, the amount of change in output is greatly increased, so that the sensing capability is increased and the response speed is remarkably increased.

Particularly, in Embodiments 4, 5 and 6, the particulate matter sensor 10 of the capacitance type is equivalent to the particulate matter sensor 10 of the resistance type whose response time is less than 1,500 and whose response speed is known to be fast Level response speed.

However, when the density of the island electrode 125 is set to more than 65%, for example, 70%, there occurs a phenomenon that the electrode is in contact with the adjacent island electrodes 125 and sticks to the reference electrodes 122 and 123 , The sensor element 120 according to the present invention can not be realized. In addition, since the amount of expensive platinum is increased, not only the economical efficiency is lowered but also the adjacent reference electrodes 122 and 123 are connected to the island electrode 125, and a short circuit occurs.

A method of manufacturing a sensor element of a particulate matter sensor according to the present invention will now be described.

A method of manufacturing a sensor element of a particulate matter sensor according to the present invention includes a mask preparation step (S110) of raising a mask patterned with a pattern including an island electrode (125), a step of applying an electrode paste to the substrate (121) An electrode paste applying step (S120), and an electrode sintering step (S140) of sintering the electrode paste.

In the mask preparation step (S110), the patterned mask including the island electrode 125 described above is mounted on the substrate. The substrate may be an alumina substrate, or may be alumina green paper.

The island electrode 125 is masked in the form of a pattern. The island electrode 125 may be formed with the reference electrodes 122 and 123 or may be formed with the reference electrodes 122 and 123 As shown in FIG.

The island electrode 125 may be formed together with the reference electrode 122 and 123. At this time, the reference electrode 122 and the island electrode 125 are both patterned in the mask.

However, since the island electrode 125 is small in size, the island electrode 125 may be additionally formed on the substrate 121 on which the reference electrode 122 and 123 are formed. At this time, it is preferable that a mesh-type mask is raised on the substrate 121 formed up to the reference electrodes 122 and 123 so that the island electrode 125 is further formed.

The electrode paste applying step (S120) applies the electrode paste to the substrate 121. For example, an electrode paste is applied to the substrate 121 by screen printing. Since the mask 121 is mounted on the substrate 121, the electrode paste is coated on the substrate 121 in a state in which a mask pattern is applied.

The electrode paste may be applied to the substrate 121 and then subjected to a heat treatment in a drying process (S130). The pre-heat treatment step (S130) is preferably applied to the case where the patterned mask is raised on the alumina substrate in the mask preparation step (S110).

In the electrode sintering step S140, the electrode coated on the substrate 121 is subjected to sintering to sinter the electrode paste to the electrode. When the patterned mask is placed on the alumina substrate in the mask preparing step S110, the electrode is firstly bonded to the substrate 121 by applying the electrode in the electrode paste applying step S120, (S140), the electrode is subjected to the secondary bonding through the firing process. Thereafter, it is heat-treated to become a sensor element of the particulate matter sensor. Meanwhile, when the patterned mask is placed on alumina green paper in the mask preparing step S110, the ceramic and the electrode paste are simultaneously sintered in the electrode sintering step (S140).

10: Particulate matter sensor
11:
12: outer housing
13: inner housing
14: Sleeve
20, 20A, 20B: sensor element
21: substrate
22, 23: reference electrode
24: Heater
120: Sensor element
121: substrate
122: first reference electrode
123: second reference electrode
124: Heater
125: island electrode
S110: mask preparation step
S120: Electrode paste application step
S130: Preheating step
S140: electrode sintering step

Claims (17)

A plurality of reference electrodes which are patterned so as to be spaced apart from each other in a line form with a conductive material on the surface of the substrate, and particulate matter contained in the exhaust gas of the engine is deposited between the reference electrodes spaced apart from each other, A sensor element of a particulate matter sensor for detecting particulate matter contained in the exhaust gas by being electrically connected,
And island electrodes formed in the form of a spot are spaced apart from each other with a gap between the reference electrodes spaced apart from each other on the surface of the substrate,
Wherein when the particulate matter is deposited on the substrate, the reference electrode is electrically connected to each other by the particulate matter and the island electrode. The method according to claim 1,
Wherein a total sum of areas of the island electrodes is formed at a predetermined ratio with respect to an area between the reference electrodes spaced apart from each other. 3. The method of claim 2,
Wherein the total area of the island electrodes is formed to be 5% or more and 65% or less of the area between the reference electrodes spaced apart from each other. The method of claim 3,
Wherein the total area of the island electrodes is 30% or more and 65% or less of the area between the reference electrodes spaced apart from each other. The method according to claim 1,
Wherein the island electrode is formed by screen printing. The method according to claim 1,
Wherein the island electrode is formed of the same material as the reference electrode. The method according to claim 6,
Wherein the island electrode is made of platinum. The method according to claim 1,
Wherein the total weight of the island electrodes is 30 wt% to 65 wt% of the total weight of the reference electrode. The method according to claim 1,
Wherein a heater is formed between the reference electrodes spaced apart from each other, the heater being not electrically connected to the reference electrode, and patterned along a direction in which the reference electrode is formed. The method according to claim 1,
Wherein a total sum of areas of the island electrodes is formed at a predetermined ratio with respect to an area between the reference electrodes. 10. The method of claim 9,
Wherein the island electrode, the reference electrode, and the heater are formed of the same material. 12. A sensor element of a particulate matter sensor, wherein the sensor element of the particulate matter according to any one of claims 1 to 11 is applied to a particulate matter sensor of a capacitive type. 12. A sensor element of a particulate matter sensor, characterized in that the sensor element of the particulate matter according to any one of claims 1 to 11 is applied to a particulate matter sensor of the resistance type. A mask preparation step of raising a patterned mask having a pattern including island electrodes according to any one of claims 1 to 13 on a substrate;
An electrode paste applying step of applying an electrode paste to the substrate by screen printing,
And an electrode sintering step of sintering the electrode paste. The method of claim 14, wherein
Wherein the mask preparation step raises the patterned mask on the alumina substrate. The method of claim 15, wherein
Further comprising a pre-heat treatment step of dry-fixing the electrode paste between the electrode paste application step and the electrode sintering step. 15. The method of claim 14,
Wherein the mask preparation step raises a patterned mask on alumina green paper. ≪ RTI ID = 0.0 > 21. < / RTI >

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