JPS60211345A - Terminal structure of ceramic substrate - Google Patents

Abstract

PURPOSE:To constitute heat-resisting and vibration-resisting terminal structure by connecting a metallic wire consisting principally of platinum, etc., and a lead wire which is curved locally to a ceramic substrate, and protecting their connection parts with a glass material. CONSTITUTION:An electrode pattern is printed with platinum paste on a green sheet 40 consisting principally of alumina and baked. Then, platinum wires 48- 50 are arranged on the electrode pattern. Then, a green sheet 41 is laminated on the green sheet 40 and bonded by thermocompression. An opening part 51 is formed in part of the green sheet 41 and a detecting element 11 is provided. Then the platinum wires 48-50 are welded to metallic wires (plate) 51-53 of nickel, etc., to form a terminal part, and those metallic wires 51-53 are curved. The terminal part is sealed with the glass material to form a protection layer, thus constituting the ceramic substrate. Thus, the metallic wires 51-53 are curved and the terminal part is protected with the glass material, so the heat- resisting and vibration-resisting terminal structure is obtained and there is no stress concentration when the metallic wires are extended, so that the metallic wires increase in strength.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a terminal structure for a ceramic substrate.

[Prior art]

Conventionally, electronic circuits have been miniaturized and weighed by forming a Tehaturn on a substrate made of ceramic material in a noble metal paste mainly made of gold or a precious metal of the platinum group and sintering it. There is.

Here, as a terminal structure for inputting and outputting signals on this type of ceramic substrate, an electrode pattern 2 is formed on the end surface of the substrate 1 using the noble metal paste, as shown in FIG. Or, as shown in FIG. For example, a platinum lead wire 6 is provided, and a ceramic plate 7 is placed on top of the platinum lead wire 6.
There is a method in which this platinum lead wire 6 is used as a terminal by closely contacting the wires and sintering them together.

However, in the case of the former terminal structure by soldering, there is a problem that the electrode pattern 2 and the substrate 1 may peel off when an external force is applied to the lead wire 3 or the substrate itself vibrates. Since the connection was made by soldering, it was impossible to use it at high temperatures. On the other hand, if the latter type of platinum lead wire is used and integrally molded with a ceramic substrate, it has heat resistance, but platinum itself has low strength, so it cannot be used in places where external force is applied to the lead wire or where it vibrates. I couldn't.

[Purpose of the invention]

Therefore, the present invention aims to provide a terminal structure for a ceramic substrate that has heat resistance and high strength so that it can sufficiently withstand even when the ceramic substrate is installed in a place with high temperatures and high vibrations. The purpose is

[Structure of the invention]

The structure of the present invention is to achieve this purpose.

A first electrode wire whose main component is a platinum group metal which is connected to a conductive portion integrally formed on a ceramic substrate and is hard-fired.

a partially curved second electrode wire joined to the first electrode wire;

an electrode protective layer made of a glass material that covers a joint portion between the first electrode wire and the second electrode wire and a part of the substrate;

The gist of this paper is the terminal structure of a ceramic substrate having the following characteristics.

Here, the reason why the first electrode wire is made of a platinum group metal as a main component is that other metals will be oxidized and become unusable when the fired crystal is fixed to the conductive part of the ceramic substrate. This electrode wire is made of platinum, iridium, palladium, and ruthenium.

It is preferable to use platinum group metals such as rhodium and osmium (platinum is particularly preferable in terms of heat resistance and cost).

Moreover, Cu, Fe, Ni, or an alloy thereof is suitable for the second electrode wire because it is suitable from the viewpoint of cost strength and heat resistance. Among these, Ni or Ni alloy is suitable because of its heat resistance, but Cu is used when an input current is required.

Furthermore, the reason why the second electrode wire is partially bent is that in the case of multiple lead wires, if there is a difference in length between the leads, when the leads are pulled.

However, when stress is concentrated on one lead, which is short and has low lead tensile strength, by providing a curved part in one part when forming a flat electrode wire, when stress is concentrated on one lead,
This is because the curved portion stretches and applies stress uniformly to the plurality of leads, thereby preventing concentration of stress and providing a sensor having stable lead strength.

Next, as the glass material, borosilicate glass, phosphate glass, lead borate glass, etc. can be used.

Among these, it is particularly preferable to use lead borate glass because it can be sealed at low temperatures and the oxidation wear and tear of the metal fittings is reduced.

〔Example〕

In the following, a ceramic substrate having a terminal structure according to the present invention will be used as a detection section for detecting a gas component or its concentration.

An example in which the present invention is applied to an oxygen sensor that detects the oxygen concentration in the exhaust gas of an internal combustion engine will be explained.

FIG. 3 is a partially sectional side view of the oxygen sensor.

In the figure, reference numeral 10 is a detection unit that includes a detection element 11 on a ceramic substrate and detects oxygen concentration, and 12 is a detection unit 1.
A metal shell formed in a cylindrical shape for holding the sensor and attaching the sensor to an internal combustion engine.

13 is a protector attached to the internal combustion engine side tip 12a of the metal shell 12 to protect the detection section 10;
4 is an inner cylinder for holding the detection part 10 together with the metal shell 12;
is being held by.

Further, the outer periphery of the metal shell 12 has a threaded portion 1 for attaching the internal combustion engine.
A gasket 18 is provided at the portion where the internal combustion engine is in contact with the wall surface to prevent exhaust gas from leaking.

Here, the filling powder 16 is made of a mixed powder of talc and glass in a ratio of 1=1, and is used to fix the detection part 10 in the inner cylinder 14, and the glass seal 17 is made of low melting point glass to prevent leakage of the detection gas. At the same time, in order to protect the terminals of the detecting section 10, a part of the substrate of the detecting section 10 and a connecting portion between a platinum lead wire and the terminal, which will be described later, are covered and filled in the inner cylinder 14.

-This glass seal 17 is one electrode v1. which constitutes the present invention. Corresponds to the protective layer.

19 is an outer cylinder attached to the metal shell 12 so as to cover the inner cylinder 14, 20 is a sealing material made of silicone rubber, and lead wires 21 to 23 are partially curved 51, 52, 53; This is for insulating and protecting the connection portions from the detection unit 10 to the terminals 31 to 33 that protrude from the glass seal 17 shown in FIG. The connections between the lead wires 21 to 23 and the terminals 31 to 33 are made in advance by placing a sealing material 20 and the lead wires 20 in the outer cylinder 19, as shown in FIG.
1 to 23, and each lead wire 21 to 2.
This is done by connecting the crimping fittings 24 to 26 to the tips of the terminals 3, and then crimping the crimping fittings 24 to 26 to the terminals 31 to 33. Note that the terminals 31 to 33 correspond to the second electrode wires constituting the present invention.

Next, the detection section 10 is created according to the procedure shown in FIGS. 6 to 9. Note that (A) shown in FIGS. 6 to 9 shows a front view of the detection unit 10.

(b) shows a sectional view taken along line A-A.

Here, in each of the above-mentioned figures 6 to 9.

40 and 41 are A120392 weight% with an average particle size of 1.5μ, Sso 24 weight%, CaO2 weight% and M
12 parts by weight of butyral resin and dibutyl phthalate (DB
P) 6 parts by weight, mixed in an organic solvent to form a slurry, and formed using a doctor blade. Green sheet 40 has a thickness of 1 m++, and green sheet 41 has a thickness of 0.2 mm. It was created in advance. Also, 42 to 47 are 796 Al2 for Pt.
It is a pattern printed with a thick film using platinum paste added with O3, and corresponds to the above-mentioned conductive part, 42 and 43 are electrode patterns that serve as electrodes of the detection element 11, and 14 serves as a heater for heating the detection element 11. Heat generating resistor pattern, 45
47 are electrode patterns for applying power to the heating resistor pattern 44 and the detection element 11 or for extracting a detection signal.

The manufacturing of the present detection unit 10 is started by thick-film printing the patterns 42 to 47 on a green sheet 40 using platinum paste, as shown in FIG. 6, and then as shown in FIG. , platinum lead wires 48 to 50 having a diameter of 0.2 ws are disposed on the electrode patterns 45 to 47, respectively.

Next, as is clear from FIG.
Openings 51 are formed by punching so that the tips of the pole patterns 42 and 43 are exposed.

A green sheet 41 is laminated and thermocompressed onto the green sheet 40 to cover all the patterns except for the tips of the electrode patterns 42 and 43.
Reference numerals 50 to 50 correspond to the first electrode wires constituting the present invention, and even after the lamination and thermocompression bonding, a portion thereof is projected to the outside.

In this way, a laminated plate in which a portion of the platinum lead wires 48 to 50 are protruded and the tips of the electrode patterns 42 and 43 are exposed is created, and this laminated plate 1500
The ceramic substrate is fired by leaving it in the atmosphere at .degree. C. for 2 hours.

Next, as shown in FIG. 9, a detection element 11 is provided in the opening 51 of the fired ceramic substrate. Add 1 mole part of platinum black, and further add 3% by weight of ethyl cellulose based on the total powder, mix in butylcarpitol (trade name of 2-(2-butoxyethoxy)ethanol) and adjust the viscosity to 300 voids. The TiO□ paste is printed as a thick film so as to fill the opening 49 and adhere to the tips of the electrode patterns 42 and 43, and then left in the atmosphere at 1200° C. for 1 hour and baked.

The platinum lead wires 48 to 50 and the terminals 31 to 33 protruding to the outside of the detection unit 10 thus created
The connection is made as shown in FIG. 1O. In FIG. 1, (a) shows a front view and (b) shows a right side view.

As shown in FIG.
．． The terminals are integrally formed by etching on a nickel plate of 3 RTAS, and the terminals are joined by placing each terminal on the platinum lead wires 48 to 50, respectively, and welding the parts with a strip weld.

Any connection method may be used to connect the platinum lead wire and the terminal as long as it does not come off due to heat or photography, and the nickel plate on which the terminals 31 to 33 are integrally formed has a detection part lO. It is fixed to the metal shell 12, and then a part of the substrate of the detection unit 10 and the platinum lead wires 48 to 5 are fixed to the metal shell 12.
The joint between 0 and terminals 31 to 33 is glass seal 1.
After being secured to the inside of the inner cylinder 14 by the protective ring 7, it is cut to a predetermined length.

Then, by applying a heating power source between the terminals 31 and 33, the heating resistor pattern 44 is heated, the detection element 11 is activated, and a change in the resistance value between the terminals 32 and 33 is detected. , it becomes possible to detect oxygen concentration.

As described above, the terminal structure of the ceramic substrate in the oxygen sensor of this embodiment is such that a platinum lead wire integrally formed with the ceramic substrate and a terminal made of a nickel plate are joined by spot welding, and the joined part is formed into a cylindrical shape together with the ceramic substrate. It is fixed and protected using low-melting glass inside. Therefore, the joint between the platinum lead wire and the terminal will not come off due to heat (and since the platinum lead wire is also reinforced with low-melting glass, it is resistant to vibrations).

Furthermore, since the terminal uses a partially curved nickel plate, it is possible to prevent the terminal itself from deteriorating. Furthermore, because the electrode wires are partially bent, even if there are differences in length between the leads, when the leads are pulled, one short curved part will stretch or the stress will be applied uniformly to the multiple leads. This material prevents stress concentration and has stable +3-)/strength. To confirm this, we measured the tensile cutting strength and found that the straight cutting strength was 38k on average.
y.

The minimum weight is 17 kg, while the curved one weighs an average of 4.
There was a particularly high effect of minimum strength at 0ky and minimum of 35ky. Therefore, the present oxygen sensor has heat resistance, vibration resistance, and durability, and can sufficiently withstand even high-temperature and high-vibration locations such as internal combustion engines.

〔Effect of the invention〕

As detailed above (1) In the terminal structure of the ceramic substrate of the present invention, a platinum group electrode wire baked and fixed to the ceramic substrate and an electrode wire made of nickel or nickel alloy are bonded, and The joints, including the parts, are protected by a protective layer made of glass material.Therefore, the terminal structure is resistant to heat and vibration (and has a terminal structure that can withstand even when the ceramic board is installed in a high-temperature and vibrating place). This makes it possible to provide a durable terminal structure.

Although a nickel wire is used in this embodiment, the present invention is not limited to this; alloys with C, u, Fe, or Ni may also be used.

[Brief explanation of drawings]

1 and 2 are perspective views showing the terminal structure of a conventional ceramic substrate, FIGS. 3 to 10 show an embodiment in which the terminal structure of the present invention is applied to an oxygen sensor, and FIGS. The figure is a partial sectional view showing the structure of this sensor, and Figures 6 to 9 are front views (A) showing the assembly process of the detection unit 10.
10 is a front view (a) and a right side view (b) showing the connection between the electrode wire and the terminal. 10...Detection part 17...Glass seal 31.32.33...Terminal 48.49.50...Platinum lead wire 51.52.53...Curved part III Figure 2 Figure II 3 9 Figure 4 Figure 1!5 Figure 6 @ Figure 7 (A) (A) (B) (B) Figure 8 Figure 9 (A) (A) Figure 10 (A) (B)

Claims (1)

[Claims] (1) A first electrode wire mainly composed of a platinum group metal, which is connected to a conductive portion integrally formed on a ceramic substrate and sintered and fixed. a partially curved second electrode wire joined to the first electrode wire; and a protective layer made of a glass material that covers a joint between the first electrode wire and the second electrode wire and a part of the substrate. Ceramic substrate terminal structure with (2) A terminal structure for a ceramic substrate according to claim 1, wherein the first electrode wire is an electrode wire containing platinum as a main component. (2) A terminal structure for a ceramic substrate according to claim 1, wherein the second electrode wire is made of nickel or a nickel alloy.