JP2020169891A - Sulfurization detection sensor, manufacturing method for sulfurization detection sensor, and mounting method for sulfurization detection sensor - Google Patents

Abstract

To provide a sulfurization detection sensor capable of accurately detecting the degree of sulfurization, and manufacturing and mounting methods for the sulfurization detection sensor.SOLUTION: A sulfurization detection sensor 10 comprises: a sulfurization detection conductor 2 and a pair of internal electrodes 7 provided in the surface of an insulating substrate 1; a sulfide gas permeable protective film 3 covering the sulfurization detection conductor 2; a pair of reverse electrodes 4 provided at both ends in a longitudinal direction on the reverse side of the insulating substrate 1; a pair of end-face electrodes 5 provided at both end faces in the longitudinal direction of the insulating substrate 1; a pair of heat-resistant barrier layers 6 provided on the surfaces of the internal electrode 7, the reverse electrode 4 and the end-face electrode 5 and composed of a Ni material; and an external electrode 8 continuously covering the surfaces of the pair of heat-resistant barrier layers 6 and the protective film 3 and composed of a Sn material. When the sulfurization detection sensor 10 is joined by soldering to a circuit board 11, the external electrode 8 covering the protective film 3 is eaten by solder and disappears, so that the protective film 3 covering the sulfurization detection conductor 2 is exposed to the outside.SELECTED DRAWING: Figure 5

Description

The present invention relates to a sulfurization detection sensor for detecting the cumulative amount of sulfurization in a corrosive environment, and a method for manufacturing and mounting such a sulfurization detection sensor.

Generally, Ag (silver) -based electrode materials with low resistivity are used as internal electrodes of electronic components such as chip resistors, but silver becomes silver sulfide when exposed to sulfide gas, and silver sulfide. Since is an insulator, there is a problem that the electronic component is broken. Therefore, in recent years, sulfurization measures have been taken, such as adding Pd (palladium) or Au (gold) to Ag to form an electrode that is difficult to sulfurize, or making the structure so that sulfurized gas does not easily reach the electrode.

However, even if such sulfurization measures are taken for electronic components, disconnection can be completely prevented when the electronic components are exposed to sulfurized gas for a long period of time or exposed to high-concentration sulfurized gas. Since it becomes difficult, it is necessary to detect the disconnection in advance and prevent the occurrence of failure at an unexpected timing.

Therefore, conventionally, as described in Patent Document 1, sulfurization that can detect the degree of cumulative sulfurization of an electronic component and detect the risk before the electronic component fails due to sulfurization disconnection or the like. Detection sensors have been proposed.

The sulfurization detection sensor described in Patent Document 1 forms a sulfurization detection conductor mainly composed of Ag on an insulating substrate, and forms a transparent and sulfide gas permeable protective film so as to cover the sulfurization detection conductor. , The end face electrodes connected to the sulfurization detection conductor are formed on both side ends of the insulating substrate. When the sulfurization detection sensor configured in this way is placed in an atmosphere containing a sulfurization gas, the sulfurization gas permeates the protective film and comes into contact with the sulfurization detection conductor over time, so that the concentration and progress of the sulfurization gas. The sulfurization detection conductor is sulfurized with time. The sulfurization detection conductor changes in the order of silver to light brown, purple, gray, and black as the degree of sulfurization progresses, and the silver constituting the sulfurization detection conductor changes to silver sulfide, so that the degree of sulfurization progresses. The resistance value gradually increases as it increases.

Then, a sulfurization detection circuit is provided on a circuit board on which other electronic components such as a chip resistor are mounted, and a sulfurization detection sensor having the above configuration is connected to this sulfurization detection circuit, which changes according to the degree of sulfurization. By detecting the amount of reflected light by irradiating the sulfurization detection conductor with light, or by detecting the resistance value of the sulfurization detection conductor that changes with the degree of sulfurization, the cumulative degree of sulfurization is detected. I have to.

Japanese Unexamined Patent Publication No. 2009-250611

However, since electronic components such as sulfurization detection sensors have different times from being manufactured to being mounted on a circuit board and used, if the sulfurization detection sensor having the above configuration is exposed to sulfurized gas during that time. , The sulfurization detection conductor will be sulfurized before it is mounted on the circuit board. That is, due to the external environment such as the storage location of the sulfurization detection sensor, the sulfurization of the sulfurization detection conductor may have progressed to some extent at the time of mounting on the circuit board, so that the cumulative degree of sulfurization can be accurately detected. become unable.

The present invention has been made in view of such an actual situation of the prior art, and a first object thereof is to provide a sulfurization detection sensor capable of accurately detecting the degree of sulfurization, and a second object thereof. An object is to provide a method of manufacturing such a sulfurization detection sensor, and a third object is to provide a method of mounting such a sulfurization detection sensor.

In order to achieve the first object, the sulfurization detection sensor of the present invention comprises a rectangular body-shaped insulating substrate, a pair of internal electrodes provided at both ends on the main surface of the insulating substrate, and a pair of internal electrodes. A sulfide detection conductor provided between the electrodes, a sulfide gas permeable protective film provided so as to cover the sulfide detection conductor, and nickel provided so as to cover the internal electrodes at both ends of the protective film. A pair of heat-resistant barrier electrodes as main components and an external electrode made of a solder material covering the pair of heat-resistant barrier electrodes are provided, and the external electrodes covering the pair of heat-resistant barrier electrodes are continuous up to a position covering the protective film. The feature is that it is provided.

In the sulfurization detection sensor configured in this way, the sulfurization gas permeable protective film covering the sulfurization detection conductor is covered with an external electrode made of a solder material, so that it can be stored until it is mounted on the circuit board. Even if it is exposed to sulfurized gas during non-use such as during transportation, the sulfurization of the sulfurized detection conductor is prevented by the external electrode having a function of blocking the sulfurized gas. Then, after mounting the sulfurization detection sensor on the circuit board, when the external electrodes are solder-bonded to the wiring pattern of the circuit board, the external electrodes provided at the positions covering the heat-resistant barrier electrodes containing nickel as the main component are on both ends of the insulating substrate. Although it remains in the portion, the external electrode provided at the position covering the protective film is absorbed by the external electrode side covering the heat-resistant barrier electrode due to solder eating and disappears. As a result, the sulfide gas permeable protective film covering the sulfurization detection conductor is exposed to the outside, so that the degree of sulfurization can be accurately detected by the sulfurization detection conductor that sulfides through the protective film during use.

In order to achieve the second object, the method for manufacturing a sulfide detection sensor according to the present invention comprises a sulfide detector containing silver as a main component on the main surface of the insulating substrate and a pair of sulfide detectors continuous on both ends of the sulfide detector. A step of forming the internal electrode, a step of forming a sulfide gas permeable protective film on the surface of the sulfide detector, and a pair of heat-resistant barrier electrodes containing nickel as a main component are formed so as to cover the internal electrode. It is characterized by including a step and a step of forming an external electrode made of a solder material that continuously covers the pair of the heat-resistant barrier electrodes and the protective film.

In order to achieve the third object, the method for mounting the sulfide detection sensor according to the present invention is to mount the sulfide detection sensor having the above configuration on a circuit board and solder between the external electrode and the wiring pattern of the circuit board. At the time of joining, the external electrode covering the protective film melts into the molten solder and is absorbed by the external electrode side covering the heat-resistant barrier electrode and disappears, so that the protective film permeable to sulfide gas is obtained. Is characterized by being exposed to the outside.

After mounting the sulfurization detection sensor whose heat-resistant barrier electrode and protective film are covered by an external electrode on the circuit board in this way, when solder-bonded to the wiring pattern of the circuit board, the position that covers the heat-resistant barrier electrode containing nickel as the main component is covered. The external electrodes provided in the above remain on both ends of the insulating substrate, but the external electrodes provided at the positions covering the protective film are absorbed by the external electrodes covering the heat-resistant barrier electrode due to solder eating and disappear. Therefore, the sulfide gas permeable protective film covering the sulfide detection conductor is exposed to the outside. As a result, even if the sulfurization detection sensor is exposed to sulfurization gas during storage or transportation until it is mounted on the circuit board, the sulfurization of the sulfurization detection conductor is carried out by an external electrode having a sulfurization gas blocking function. In the state of use after mounting the sulfurization detection sensor on the circuit board, the degree of sulfurization can be accurately detected by the sulfurization detection conductor that sulfides through the protective film.

According to the present invention, it is possible to prevent the sulfurization detection sensor from undesirably sulfurizing when not in use before mounting on the circuit board, and it is possible to accurately detect the degree of sulfurization after mounting on the circuit board. ..

It is a top view of the sulfurization detection sensor which concerns on embodiment of this invention. It is sectional drawing which follows the line II-II of FIG. It is a top view which shows the manufacturing process of the sulfurization detection sensor. It is sectional drawing which shows the manufacturing process of the sulfurization detection sensor. It is explanatory drawing which shows the procedure of mounting the sulfurization detection sensor on a circuit board.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a sulfurization detection sensor according to an example of the embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are II-II of FIG. It is a cross-sectional view along the line.

As shown in FIGS. 1 and 2, the sulfurization detection sensor 10 according to the present embodiment includes a rectangular-shaped insulating substrate 1, a sulfurization detection conductor 2 provided on the surface of the insulating substrate 1, and a pair of internal electrodes 7. A protective film 3 provided so as to cover the sulfide detection conductor 2, a pair of back electrodes 4 provided on both ends in the longitudinal direction of the back surface of the insulating substrate 1, and both end surfaces in the longitudinal direction provided on the insulating substrate 1. The pair of end face electrodes 5 provided, the pair of heat-resistant barrier layers 6 provided on the surfaces of the internal electrodes 7, the back electrodes 4 corresponding to the internal electrodes 7, and the end face electrodes 5, and these heat-resistant barrier layers 6 and the protective film 3 are continuously formed. It is mainly composed of an external electrode 8 provided so as to cover the surface.

The insulating substrate 1 is obtained by dividing a large-format substrate, which will be described later, along vertical and horizontal dividing grooves and taking a large number of the insulating substrate 1, and the main component of the large-format substrate is a ceramic substrate containing alumina as a main component.

The sulfurization detection conductor 2 and the pair of internal electrodes 7 are obtained by screen-printing an Ag-based paste containing silver as a main component, drying and firing. Here, the sulfurization detection conductor 2 and the pair of internal electrodes 7 may be formed separately and have a continuous structure as shown in FIG. 2A, or may be formed simultaneously as shown in FIG. 2B. An integrated structure having a uniform film thickness may be used.

The protective film 3 is made of a sulfide gas permeable material, and is obtained by screen-printing a resin paste such as a silicone resin or a fluororesin and heat-curing it. As will be described later, when the sulfurization detection sensor 10 is mounted on a circuit board and used for detecting sulfurization gas, the protective film 3 covers the sulfurization detection conductor 2 and is exposed to the outside. In addition, the protective film 3 makes it less susceptible to external contact with the sulfurization detection conductor 2, humidity, and the like.

The pair of back electrodes 4 are made by screen-printing an Ag-based paste containing silver as a main component, drying and firing, and the back electrodes 4, the sulfurization detection conductor 2 and the internal electrode 7 may be formed in separate steps. It is good, but it may be formed at the same time.

The pair of end face electrodes 5 are those obtained by sputtering Ni / Cr on the end faces of the insulating substrate 1 or applying Ag-based paste and curing by heating. These end face electrodes 5 are an internal electrode 7 and a corresponding back electrode. It is formed so as to be conductive with 4.

The pair of heat-resistant barrier layers 6 are Ni-plated layers formed by electrolytic plating, and the surfaces of the internal electrode 7, the end face electrode 5, and the back electrode 4 are covered with the heat-resistant barrier layer 6 in a U-shaped cross section. ..

The pair of external electrodes 8 are Sn-plated layers formed by electrolytic plating, and the surfaces of the pair of heat-resistant barrier layers 6 and the protective film 3 are continuously coated by the external electrodes 8.

Next, among the sulfurization detection sensors 10 configured in this way, the manufacturing process of the sulfurization detection sensor 10 having the configuration shown in FIG. 2B will be described with reference to FIGS. 3 and 4. 3 (a) to 3 (f) are plan views of the large-format substrate used in this manufacturing process as seen on the surface, and FIGS. 4 (a) to 4 (f) are the lengths of FIGS. 3 (a) to 3 (f). Cross-sectional views corresponding to one chip along the central portion of the direction are shown.

First, as shown in FIGS. 3A and 4A, a large-format substrate 10A on which a large number of insulating substrates 1 are taken is prepared. The large-format substrate 10A is provided with a primary dividing groove and a secondary dividing groove in a grid pattern in advance, and each of the squares divided by the two dividing grooves serves as a chip region for one piece. In FIG. 3, a large-format substrate 10A corresponding to one chip region is represented as a representative, but in reality, each step described below is collectively applied to a large-format substrate corresponding to a large number of chip regions. Is done.

That is, as shown in FIGS. 3 (b) and 4 (b), an Ag-based paste containing Ag as a main component is screen-printed on the surface of the large-format substrate 10A, and then dried and fired to obtain a large-format substrate. A sulfide detection conductor 2 that covers the entire surface of the substrate 10A and a pair of internal electrodes 7 are simultaneously formed. Further, at the same time or before and after this, an Ag-based paste is screen-printed on the back surface of the large-format substrate 10A, and then dried and fired to form a pair of back electrodes 4 facing each other at predetermined intervals. .. As shown in FIGS. 3 (b) and 4 (b), when the sulfurization detection conductor 2 and the internal electrode 7 are formed at the same time, the central portion in the drawing is the sulfurization detection conductor 2 and both end portions are a pair of internal parts. It becomes the electrode 7. However, the sulfurization detection conductor 2 and the internal electrode 7 may be formed separately. In that case, a pair of internal electrodes 7 are formed at a predetermined interval, and then the sulfurization detection conductor 2 is formed between them to form an end portion. It suffices to overlap each other (see FIG. 2A).

Next, a resin paste such as a silicone resin or a fluororesin is screen-printed so as to cover the sulfurization detection conductor 2 located between the pair of internal electrodes 7, and this is heat-cured to be shown in FIG. 3 (c). As shown in 4 (c), a sulfide gas permeable protective film 3 covering the sulfide detection conductor 2 is formed. The protective film 3 covers only the sulfurization detection conductor 2, and the pair of internal electrodes 7 are exposed without being covered by the protective film 3.

Next, the large-format substrate 10A is first divided into strip-shaped substrates 10B along the primary dividing groove, and then Ni / Cr is sputtered on the divided surfaces of the strip-shaped substrate 10B to show FIGS. 3 (d) and 4 (d). As shown in (d), a pair of end face electrodes 5 are formed to connect both ends of the sulfurization detection conductor 2 in the longitudinal direction and the corresponding back electrodes 4. Instead of sputtering Ni / Cr on the divided surface of the strip-shaped substrate 10B, the end face electrode 5 may be formed by applying an Ag-based paste and heat-curing it.

Next, by electroplating the strip-shaped substrate 10B to form a Ni plating layer, as shown in FIGS. 3 (e) and 4 (e), the internal electrode 7, the end face electrode 5, and the back electrode are formed. A pair of heat-resistant barrier layers 6 covering the surface of 4 are formed.

Next, after pretreatment such as Sn sputtering is performed so as to cover the protective film 3, the strip-shaped substrate 10B is secondarily divided into a plurality of chip-shaped substrates 10C along the secondary dividing groove, and these chip-shaped substrates 10C are secondaryly divided. As shown in FIGS. 3 (f) and 4 (f), the entire surface of the heat-resistant barrier layer 6 and the surface of the protective film 3 are continuously formed by electroplating the surface of the heat-resistant barrier layer 6 to form a Sn-plated layer. The external electrode 8 to be covered is formed. As a result, the sulfurization detection sensor 10 shown in FIGS. 1 and 2 (b) is completed.

The sulfurization detection sensor 10 configured in this way is used by exposing the circuit board to an atmosphere containing sulfide gas after being mounted on the circuit board together with other electronic components, until it is mounted on the circuit board. During non-use (during storage, transportation, etc.), the sulfide detection conductor 2 is covered with an external electrode 8 that is impermeable to sulfide gas. Therefore, even if the sulfurization detection sensor 10 is exposed to sulfurized gas during non-use until it is mounted on the circuit board, the sulfurization detection conductor 2 is not sulphurized, and the state is mounted on the circuit board. Can be maintained up to.

FIG. 5 is a cross-sectional view showing a procedure for mounting the sulfurization detection sensor 10 on the circuit board 11. First, as shown in FIG. 5A, cream solder 13a is applied in advance to the wiring pattern 12 provided on the surface of the circuit board 11, and the surface (main surface) of the insulating substrate 1 faces upward on the wiring pattern 12. After mounting the sulfide detection sensor 10 in this position, the wiring pattern 12 of the circuit board 11 and the external electrode 8 of the sulfide detection sensor 10 are fixed with solder 13. The solder 13 is a lead-free solder containing tin as a main component (for example, Sn96.5% -Ag3% -Cu0.5%), and after melting the cream solder 13a applied on the wiring pattern 12 with the heat of the reflow furnace, By cooling and solidifying this, the wiring pattern 12 and the external electrode 8 are joined by the solder 13.

At the time of such solder bonding, the external electrode 8 covering the protective film 3 and the heat-resistant barrier layer 6 is made of a solder material (Sn). Therefore, as shown in FIG. 5 (b), the external electrode 8 covering the protective film 3 is soldered. Due to being eaten, it is absorbed by the external electrode 8 side that covers the heat-resistant barrier layer 6 and disappears, and as a result, the protective film 3 that covers the sulfide detection conductor 2 is exposed to the outside. The heat-resistant barrier layer 6 made of the Ni-plated layer is not solder-eaten, and a solder fillet is formed from the upper surface to the end surface of the heat-resistant barrier layer 6. As a result, even if the sulfurization detection sensor 10 is exposed to sulfurization gas during non-use such as storage or transportation until it is mounted on the circuit board 11, sulfurization detection is performed by the external electrode 8 having a sulfurization gas blocking function. The sulfurization of the conductor 2 can be prevented, and in the used state after the sulfurization detection sensor 10 is mounted on the circuit board 11, the degree of sulfurization is accurately detected by the sulfurization detection conductor 2 that sulphurizes through the protective film 3. Can be done.

As described above, in the sulfurization detection sensor 10 according to the present embodiment, since the sulfurization gas permeable protective film 3 is covered with the external electrode 8 made of a solder material, it is mounted on the circuit board 11. Even if it is exposed to sulfurized gas during non-use such as during storage or transportation, the sulfurization of the sulfurization detection conductor 2 is prevented by the external electrode 8 having a function of blocking the sulfurized gas. Then, after mounting the sulfurization detection sensor 10 on the circuit board 11, when the external electrode 8 is solder-bonded to the wiring pattern 12 of the circuit board 11, the external electrode 8 covering the heat-resistant barrier layer 6 made of the Ni plating layer is an insulating substrate. Although it remains at both ends of 1, the external electrode 8 covering the protective film 3 disappears due to solder eating, and the protective film 3 covering the sulfurization detection conductor 2 is exposed to the outside. Therefore, it is used after mounting on the circuit board 11. In the state, the degree of sulfide can be accurately detected by the sulfide detection conductor 2 that sulfides through the protective film 3.

10 Sulfurization detection sensor 1 Insulation substrate 2 Sulfurization detection conductor 3 Protective film 4 Back electrode 5 End face electrode 6 Heat-resistant barrier layer 7 Internal electrode 8 External electrode 10A Large format substrate 10B Strip-shaped substrate 10C Chip-shaped substrate 11 Circuit board 12 Wiring pattern 13 Solder

Claims (3)

A rectangular-shaped insulating substrate, a pair of internal electrodes provided at both ends on the main surface of the insulating substrate, a sulfide detection conductor provided between the pair of internal electrodes, and a sulfide detection conductor so as to cover the sulfide detection conductor. It covers the provided protective film for sulfide gas permeability, a pair of nickel-based heat-resistant barrier electrodes provided on both ends of the protective film so as to cover the internal electrodes, and the pair of heat-resistant barrier electrodes. Equipped with an external electrode made of solder material,
A sulfurization detection sensor characterized in that the external electrodes covering the pair of heat-resistant barrier electrodes are continuously provided up to a position covering the protective film. A step of forming a sulfur-containing detector containing silver as a main component on the main surface of the insulating substrate and a pair of continuous internal electrodes on both ends of the sulfur detector.
A step of forming a sulfide gas permeable protective film on the surface of the sulfide detector, and
A step of forming a pair of heat-resistant barrier electrodes containing nickel as a main component so as to cover the internal electrodes, and
A step of forming an external electrode made of a pair of heat-resistant barrier electrodes and a solder material that continuously covers the protective film, and
A method for manufacturing a sulfurization detection sensor, which comprises. When the sulfurization detection sensor according to claim 1 is mounted on a circuit board and solder-bonded between the external electrode and the wiring pattern of the circuit board, the external electrode covering the protective film is molten solder. A method for mounting a sulfurization detection sensor, characterized in that the protective film is exposed to the outside by being absorbed by the external electrode side that covers the heat-resistant barrier electrode and disappearing.