JP2020153853A - Sulfuration detection sensor and method for mounting the same - Google Patents

Abstract

To provide a sulfuration detection sensor, capable of preventing a sulfuration detection sensor from being undesirably sulfurated when not in use before being mounted on a circuit board and accurately detecting the degree of sulfuration after being mounted on the circuit board.SOLUTION: A sulfuration detection sensor 10 comprises: a rectangular parallelepiped shaped insulating substrate 1; a pair of outer electrodes 6 provided in both end portions of the insulating substrate 1 in the longitudinal direction, a sulfuration detection conductor 2 provided on the surface of the insulating substrate 1 so as to connect between the outer electrodes; and a dissolution peeling type resist film 3 having sulfuration gas impermeability and provided so as to cover a central portion of the sulfuration detection conductor 2. When peeling and removing the dissolution peeling type resist film 3 after mounting the sulfuration detection sensor 10 on a circuit board 11, the central portion of the sulfuration detection conductor 2 is exposed to the outside to form a sulfuration detector 2a, and in the state, the sulfuration detection sensor 10 is exposed to an atmosphere including sulfuration gas and used.SELECTED DRAWING: Figure 2

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 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 electronic parts are 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 a 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 with the passage of 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 mounting such a sulfurization detection sensor.

In order to achieve the first object, the sulfurization detection sensor of the present invention has a rectangular body-shaped insulating substrate, a pair of external electrodes provided at both ends in the longitudinal direction of the insulating substrate, and between the pair of external electrodes. A sulfide detection conductor provided on the main surface of the insulating substrate so as to connect the sulfide detection conductor, and a sulfide gas opaque dissolution and peeling type resist film provided so as to cover at least a part of the sulfide detection conductor. The sulfide detection conductor is characterized by having a sulfide detection portion exposed to the outside by removing the dissolution-release type resist film.

In the sulfurization detection sensor configured in this way, since the surface of the sulfurization detection conductor is covered with a dissolution-release resist film that is impermeable to sulfurized gas, it can be stored or transported until it is mounted on a circuit board. Even when exposed to sulfurized gas during non-use, the sulfurization of the sulfurization detection conductor is blocked by the dissolution-release resist film. Then, after mounting the sulfurization detection sensor on the circuit board, when the dissolution-release type resist film is peeled off by immersing the circuit board in a solvent or the like, the sulfurization detection conductor in the portion covered by the dissolution-release type resist film until then. Is exposed to the outside and becomes a sulfurization detection unit, so that the degree of sulfurization can be accurately detected by the sulfurization detection unit during use.

In the above configuration, when a pair of surface electrodes connected to both ends of the sulfide detection conductor are provided on the main surface of the insulating substrate so that the melt-release type resist film covers the entire sulfide detection conductor and a part of the surface electrodes. Since the external electrode and the sulfide detection conductor are substantially separated from each other, it is possible to prevent the sulfide detection conductor from being damaged by stress such as heat during mounting connected to the external electrode.

In order to achieve the second 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 to perform between the external electrode and the wiring pattern of the circuit board. After joining with solder or a conductive adhesive, the dissolution-release type resist film is removed with a solvent to form a sulfide detection portion exposed to the outside on the sulfide detection conductor.

In this way, after joining the external electrode of the sulfurization detection sensor and the wiring pattern of the circuit board with solder or a conductive adhesive, the sulfurization detection conductor is immersed in a solvent together with the circuit board to form a dissolution-release resist film. When removed, a sulfurization detection part exposed to the outside is formed on the sulfurization detection conductor at this point, so that the sulfurization of the sulfurization detection sensor during non-use before mounting is surely prevented, and the degree of sulfurization is determined after mounting. It can be detected accurately.

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 1st 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. It is a top view of the sulfurization detection sensor which concerns on 2nd Embodiment of this invention. It is sectional drawing which follows the line VII-VII of FIG. 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 the sulfurization detection sensor according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line II-II of FIG. Is.

As shown in FIGS. 1 and 2, the sulfide detection sensor 10 according to the first embodiment includes a rectangular-shaped insulating substrate 1, a sulfide detection conductor 2 provided on the surface of the insulation substrate 1, and sulfide detection thereof. A melt-release type resist film 3 provided so as to cover the central portion of the conductor 2, a pair of back electrodes 4 provided at both ends in the longitudinal direction of the back surface of the insulating substrate 1, and both end surfaces in the longitudinal direction of the insulating substrate 1. It is mainly composed of a pair of end face electrodes 5 provided, and a pair of external electrodes 6 provided on the surfaces of both ends of the sulfurization detection conductor 2, the end face electrodes 5, and the back electrode 4.

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 sulfide detection conductor 2 is obtained by screen-printing an Ag-based paste containing silver as a main component, drying and firing, and is formed so as to cover most of the surface of the insulating substrate 1 except for both ends in the lateral direction. There is. Further, the sulfurization detection conductor 2 has an Ag content adjusted in consideration of the timing at which the wire is desired to be broken by being exposed to the sulfurization gas.

The melt-release type resist film 3 (hereinafter referred to as a resist film) is made of a sulfide gas impermeable material in which sulfide gas is difficult to permeate, and is obtained by screen-printing a phenolic resin paste or the like and heat-curing it. Since the resist film 3 is formed so as to cover the central portion of the sulfurization detection conductor 2, the sulfurized gas does not pass through the resist film 3 and reach the central portion of the sulfurization detection conductor 2. However, the resist film 3 can be peeled off using an alcohol solvent or the like, and as will be described later, a sulfurization detection portion exposed to the outside is provided at the center of the sulfurization detection conductor 2 by peeling off the resist film 3. It is formed. Further, it is necessary to select the material and plating solution of the resist film 3 so that the external electrode 6 is not peeled off by the plating solution or the like when the external electrode 6 is formed after the resist film 3 is formed.

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 these back electrodes 4 and the sulfurization detection conductor 2 may be formed in separate steps, but are formed at the same time. You may.

The pair of end face electrodes 5 are obtained by sputtering Ni / Cr on the end faces of the insulating substrate 1 or applying Ag-based paste and heat-curing the end face electrodes 5, and these end face electrodes 5 are both ends in the longitudinal direction of the sulfurization detection conductor 2. It is formed so as to conduct electricity between the surface electrode 4 and the corresponding back electrode 4.

The pair of external electrodes 6 has a two-layer structure consisting of a barrier layer and an external connection layer, of which the barrier layer is a Ni plating layer formed by electrolytic plating and the external connection layer is a Sn plating layer formed by electrolytic plating. .. By these external electrodes 6, both ends of the sulfurization detection conductor 2 exposed from the resist film 3 and the surfaces of the end face electrode 5 and the back electrode 4 are covered with a U-shaped cross section.

Next, the manufacturing process of the sulfurization detection sensor 10 will be described with reference to FIGS. 3 and 4. 3 (a) to 3 (e) are plan views of the large-format substrate used in this manufacturing process as seen on the surface, and FIGS. 4 (a) to 4 (e) are the lengths of FIGS. 3 (a) to 3 (e). 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. The sulfide detection conductor 2 is formed on the surface of the substrate 10A. 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. ..

Next, a phenolic resin paste is screen-printed on the center of the sulfurization detection conductor 2 and heat-cured to heat and cure the phenol-based resin paste to the center of the sulfurization detection conductor 2 as shown in FIGS. 3 (c) and 4 (c). A sulfide gas impermeable resist film 3 is formed so as to cover the portion.

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 so as to cover the divided surface of the strip-shaped substrate 10B. As shown in FIG. 4D, 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, the strip-shaped substrate 10B is secondarily divided into a plurality of chip-shaped substrates 10C along the secondary dividing groove, and the chip-shaped substrates 10C are electrolytically plated to form a Ni—Sn plating layer. As shown in FIGS. 3 (e) and 4 (e), external electrodes 6 having a U-shaped cross section are formed at both ends of the chip-shaped substrate 10C in the longitudinal direction. These external electrodes 6 cover both ends of the sulfurization detection conductor 2 exposed from the resist film 3 and the surfaces of the end face electrode 5 and the back electrode 4, and the sulfurization detection sensor 10 shown in FIGS. 1 and 2 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. The surface of the sulfide detection conductor 2 is covered with a sulfide gas impermeable resist film 3 and an external electrode 6 during non-use (during storage, transportation, etc.). 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 a circuit board. First, as shown in FIG. 5A, the sulfide detection sensor 10 is mounted on the circuit board 11 with the surface (main surface) of the insulating substrate 1 on which the sulfide detection conductor 2 and the resist film 3 are formed facing upward. Then, the wiring pattern 12 provided on the surface of the circuit board 11 and the external electrode 6 of the sulfurization detection sensor 10 are joined by the solder 13. It is also possible to use a conductive adhesive instead of solder. After that, the sulfide detection sensor 10 together with the circuit board 11 is immersed in a solvent so as not to adversely affect other electronic components, and ultrasonic vibration is applied as necessary to peel off and remove the resist film 3. FIG. As shown in (b), since the central portion of the sulfurization detection conductor 2 previously covered with the resist film 3 is exposed, the sulfurization detection portion 2a exposed to the outside is exposed to the central portion of the sulfurization detection conductor 2 at this point. It is formed. Therefore, if the sulfurization detection sensor 10 together with the circuit board 11 is subsequently exposed to an atmosphere containing sulfur gas and put into a used state, the degree of sulfurization can be accurately detected by the sulfurization detection unit 2a exposed immediately before.

As described above, in the sulfurization detection sensor 10 according to the first embodiment, since the surface of the sulfurization detection conductor 2 is covered with a dissolution-peeling resist film 3 having sulfide gas impermeable property, the circuit board 11 Even if it is exposed to sulfurized gas during non-use such as during storage or transportation until it is mounted on the conductor 2, the sulfurization of the sulfurization detection conductor 2 is blocked by the resist film 3 having the sulfurization gas impermeable property. Then, after the sulfurization detection sensor 10 is mounted on the circuit board 11, the dissolution and peeling type resist film 3 is peeled off and removed by immersing the sulfurization detection sensor 10 together with the circuit board 11 in a solvent. Since the central portion of the sulfurization detection conductor 2 covered with is exposed to the outside to become the sulfurization detection unit 2a, the degree of sulfurization can be accurately detected by the sulfurization detection unit 2a.

FIG. 6 is a plan view of the sulfurization detection sensor 20 according to the second embodiment of the present invention, FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 6, and the parts corresponding to FIG. 1 are designated by the same reference numerals. Therefore, the duplicate explanation is omitted.

As shown in FIGS. 6 and 7, the sulfurization detection sensor 20 according to the second embodiment includes a rectangular body-shaped insulating substrate 1 and a pair of surface electrodes (1) provided at both ends in the longitudinal direction on the surface of the insulating substrate (1). The internal electrode) 7, the sulfide detection conductor 2 provided on the surface of the insulating substrate 1 so as to bridge between the surface electrodes 7, the entire sulfide detection conductor 2 and a part of the surface electrode 7 are covered. The provided sulfide gas impermeable lysis and peeling type resist film 3, the pair of back electrodes 4 provided at both ends in the longitudinal direction on the back surface of the insulating substrate 1, and the provided end surfaces in the longitudinal direction of the insulating substrate 1. It is mainly composed of a pair of end face electrodes 5 and a pair of external electrodes 6 provided on the surfaces of the front electrode 7, the end face electrode 5, and the back electrode 4. That is, the major difference between the sulfurization detection sensor 20 according to the second embodiment and the sulfurization detection sensor 10 according to the first embodiment is that a pair of surface electrodes provided at both ends in the longitudinal direction on the surface of the insulating substrate 1. The sulfurization detection conductor 2 is connected between the 7s, and the other configurations are basically the same.

As described above, the pair of surface electrodes 7 connected to both ends of the sulfide detection conductor 2 are provided, and the entire sulfide detection conductor 2 and a part of the surface electrode 7 are covered with the melt-release type resist film 3, which is substantially present. Since the external electrode 6 and the sulfide detection conductor 2 are separated from each other, it is possible to prevent the sulfide detection conductor 2 from being damaged by stress such as heat during mounting connected to the external electrode 6.

FIG. 8 is a cross-sectional view showing a procedure for mounting the sulfurization detection sensor 20 having the above configuration on the circuit board 11. First, as shown in FIG. 8A, the sulfurization detection sensor 20 is mounted on the circuit board 11 with the surface (main surface) of the insulating substrate 1 facing upward, and the wiring provided on the surface of the circuit board 11 is provided. The pattern 12 and the external electrode 6 of the sulfurization detection sensor 20 are joined with a solder 13 (or a conductive adhesive). After that, when the sulfurization detection sensor 10 together with the circuit board 11 is immersed in a solvent to peel off and remove the resist film 3, as shown in FIG. 8B, the sulfurization detection conductor 2 previously covered with the resist film 3 At this point, the sulfurization detection conductor 2 is formed with the sulfurization detection portion 2a exposed to the outside because the surface of the is exposed. Therefore, if the sulfurization detection sensor 20 together with the circuit board 11 is exposed to an atmosphere containing sulfur gas in this state and put into a used state, the degree of sulfurization can be accurately detected by the sulfurization detection unit 2a exposed immediately before.

As described above, in the sulfurization detection sensor 20 according to the second embodiment, since the surface of the sulfurization detection conductor 2 is covered with the dissolution-peeling resist film 3 having sulfide gas impermeable property, the circuit board 11 Even if it is exposed to sulfurized gas during non-use such as during storage or transportation until it is mounted on the conductor 2, the sulfurization of the sulfurization detection conductor 2 is blocked by the resist film 3 having the sulfurization gas impermeable property. Then, after the sulfurization detection sensor 20 is mounted on the circuit board 11, the dissolution and peeling type resist film 3 is peeled off and removed by immersing the sulfurization detection sensor 20 together with the circuit board 11 in a solvent, and the resist film 3 is peeled off until then. Since the surface of the sulfurization detection conductor 2 covered with is exposed to become the sulfurization detection unit 2a, the degree of sulfurization can be accurately detected by the sulfurization detection unit 2a, and the same operation as in the first embodiment. It can be effective.

1 Insulated substrate 2 Sulfurization detection conductor 2a Sulfurization detection part 3 Dissolution and peeling type resist film 4 Back electrode 5 End face electrode 6 External electrode 7 Front electrode 10, 20 Sulfurization detection sensor 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 external electrodes provided at both ends in the longitudinal direction of the insulating substrate, and a sulfurization detection conductor provided on the main surface of the insulating substrate so as to connect the pair of external electrodes. A sulfide gas impermeable dissolution-release type resist film provided so as to cover at least a part of the sulfide detection conductor is provided.
The sulfurization detection conductor is characterized by having a sulfurization detection portion exposed to the outside by removing the dissolution-release type resist film. In the sulfurization detection sensor according to claim 1, a pair of surface electrodes connected to both ends of the sulfurization detection conductor are provided on the main surface of the insulating substrate, and the melt-release type resist film forms the entire sulfurization detection conductor and the said. A sulfurization detection sensor characterized by covering a part of the surface electrode. The sulfurization detection sensor according to claim 1 or 2 is mounted on a circuit board, and after joining the external electrode and the wiring pattern of the circuit board with solder or a conductive adhesive, the dissolution-release type resist film is used. A method for mounting a sulfide detection sensor, characterized in that a sulfide detection portion exposed to the outside is formed on the sulfide detection conductor by removing the sulfide with a solvent.

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