JPH08321405A - Electronic element and its production - Google Patents

Abstract

PURPOSE: To obtain an electronic device which can be produced easily and at a low cost and is superior in reliability. CONSTITUTION: An outer electrode 2 made mainly of Ag is formed on both end parts of a ceramic base body 1 respectively, and an insulation film 11 is formed on the surface of the body 1, leaving the electrode 2 thereon as it is by means of the pad printing method. At this time, since one main surface of the body 1 and an approximately half area of two sides thereof are coated with insulation film material through every printing, the entire coating can be completed by two printing operations. Then, an Ni plating film 3 and Sn plating film 4 are formed on the surface of the electrode 2. The film 11 is made of inorganic material such as glass, etc., or organic material such as epoxy resin, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device, and more particularly to an electronic device having an external electrode provided on the surface of a ceramic body and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a method of manufacturing an electronic element having a ceramic body, such as a thermistor element or a varistor element, after forming a glass coating on both main surfaces of a ceramic wafer,
After cutting the wafer into chips for each product size and forming a glass coating on the side surface of the chip-shaped ceramic body, next, an external electrode is formed at the end of the ceramic body by the dip method, and further A method is known in which Ni plating and Sn (or solder) plating are sequentially performed on the external electrodes to prevent solder nicks (for example, JP-A-4-334).
(See Japanese Patent Publication No. 001).

Separately from this, the chip-shaped ceramic body is dipped in a glass paste to form a glass coating on the entire ceramic body, and then external electrodes are formed on the end portions of the ceramic body by a dipping method. Further, a method is known in which Ni plating and Sn (solder) plating are sequentially performed on the external electrodes (see, for example, JP-A-5-283206 and JP-A-6-61008).

[0004]

In the former of those described in the prior art, since the screen printing method is adopted for forming the glass film on the side surface of the ceramic body, the ridge line portion of the ceramic body is used. In some cases, the glass film could not be reliably formed and the ceramic body was exposed. In addition, a plating film may be deposited on the ridge portion during Ni plating or Sn plating, causing a short circuit between external electrodes. Further, when the ceramic wafer is cut into chips, a dicing cut method is used to prevent cracking of the glass coating or the ceramic wafer, but this also leads to high manufacturing costs.

Further, in the latter, when the external electrode is fired, the glass coating sandwiched between the external electrode and the ceramic body partially diffuses into the external electrode, but not all diffuses, There is a possibility that defective electrical bonding between the electrode and the ceramic body may occur. Therefore, the purpose of the present invention is to
An object of the present invention is to provide an electronic device having a low manufacturing cost, easy to manufacture, and excellent in reliability, and a manufacturing method thereof.

[0006]

In order to achieve the above object, an electronic element according to the present invention is provided with an external electrode and an insulating coating on the surface of a ceramic body, and the insulating coating is an inorganic material or an organic material. It is made of wood. As the inorganic material, glass or the like is used, and as the organic material, epoxy-based, phenol-based, acrylic-based, melamine-based,
An alkyd resin or the like is used. As the ceramic body, a positive characteristic thermistor element body, a negative characteristic thermistor element body, a varistor element body or the like is used.

Further, the method of manufacturing an electronic element according to the present invention comprises a step of forming an external electrode and an insulating coating on the surface of the ceramic body, and adopts a pad printing method when forming the insulating coating. And Furthermore, the method for manufacturing an electronic element according to the present invention is characterized in that a plating film is provided on the surface of the external electrode.

[0008]

In the electronic device according to the present invention, the surface of the ceramic body is covered with an insulating coating, leaving the external electrodes, so that the plating film is deposited only on the external electrodes. In addition, in the method for manufacturing an electronic device according to the present invention, since the insulating coating is formed by the pad printing method, as shown in FIG. 4, one main surface and one half of the two side surfaces are formed by one printing. The insulating coating material is applied to the printing material to reduce printing work. Furthermore, by forming a plating film on the surface of the external electrode, when the electronic element is soldered to a circuit board or the like, the plating film suppresses soldering of the external electrode.

[0009]

Embodiments of an electronic device and a method of manufacturing the same according to the present invention will be described below with reference to the accompanying drawings. Each embodiment will be described by taking a thermistor as an example of the electronic element. [First Embodiment, FIGS. 1 to 10] As shown in FIG. 1, a thermistor comprises a ceramic body 1, external electrodes 2 provided at both ends of the ceramic body 1, and a surface of the external electrode 2. The Ni plating film 3 and the Sn (or solder) plating film 4 are provided, and the insulating coating 11 provided on the surface of the ceramic body 1.

The ceramic body 1 may be either a positive characteristic thermistor element body or a negative characteristic thermistor element body. The insulating coating 11 is made of an inorganic material such as glass or an organic material such as an epoxy solder resist ink. By forming the insulating coating 11 on the surface of the ceramic body 1 on which the external electrodes 2 are formed excluding the external electrodes 2, a plating film is formed on the ceramic body 1 on which the insulating coating 11 is formed. Even if it is formed, the plating film is not formed on the portion other than the surface of the external electrode 2. The insulating coating 11 also has an effect of preventing the soldering flux from entering the inside of the ceramic body 1 when the thermistor is soldered to a circuit board or the like.

Next, a method of manufacturing the thermistor shown in FIG. 1 will be described. The ceramic body 1 shown in FIG. 2 is prepared. The ceramic body 1 is manufactured by the following procedure. Compounds such as Mn, Ni, Co and Cu are kneaded together with a binder agent to form a slurry, which is then formed into a sheet by the doctor blade method and then cut into a predetermined size to obtain a green sheet. After stacking a plurality of these green sheets and pressing them together, they are cut into chips. In the case of the first embodiment, the size is 2.1 mm × 1.5 mm × 1.3 mm. Next, this chip is placed at a temperature of 1300 ° C.
The ceramic body 1 is obtained by firing for a time. In the case of the first example, a ceramic body having a size of 1.7 mm × 1.2 mm × 1.0 mm was obtained. After that, the ceramic body 1 is barrel-polished to round the corners and the ridges.

Next, as shown in FIG. 3, external electrodes 2 are provided on both ends of the ceramic body 1. The external electrode 2 is Ag
Alternatively, after a conductive paste containing Ag-Pd alloy as a main component and glass as a binder is applied by a dip method and dried,
It was formed by firing at a temperature of about 800 ° C. Next, as shown in FIG. 4, an insulating coating 11 is provided on the ceramic body 1. The insulating coating 11 is applied by the pad printing method and then dried. Here, the pad printing method will be described with reference to FIGS. As shown in FIG. 5, an intaglio plate 2 having a recess 20a having a depth of about 0.03 mm provided on the upper surface of a steel plate (size: 1.2 mm × 2.4 mm × 0.1 mm).
Prepare 0. The insulating coating material 11 is applied to the upper surface of the intaglio plate 20, and the blade 26 scrapes off the excess insulating coating material 11 other than the one clogged in the recess 20 a of the intaglio plate 20.

Next, as shown in FIG. 6, the pad 28 made of silicon rubber having a convex curved surface is lowered to transfer the insulating coating material 11 filled in the concave portion 20a onto the surface of the pad 28, and then, The pad 28 is raised. Next, as shown in FIG. 7, the pad 2 is inserted from above the ceramic body 1.
By lowering 8 and pressing the insulating coating material 11 transferred to the surface of the pad 28 against the ceramic body 1, the insulating coating material 11 is retransferred to the ceramic body 1.
At this time, by utilizing the elasticity and flexibility of the pad 28,
The insulating coating material 11 is applied to substantially the upper half of the main surface and the side surface of the ceramic body 1 by a single operation.

As described above, unlike the screen printing method, the pad printing method can form the insulating coating 11 not only on the main surface of the ceramic body 1 but also on the side surfaces thereof in a single operation. It can be reduced. Further, according to the pad printing method, the insulating coating film 11 is surely formed even on the ridgeline portion of the ceramic body 1. Therefore, when the plated films 3 and 4 are formed on the external electrode 2 which will be described later, the plated film is ridgelined. It is possible to prevent short-circuiting between the external electrodes 2 without worrying about deposition on the part.

Further, since the screen printing method requires smoothness on the printing surface, it is impossible to print on the ceramic body 1 on which the external electrodes 2 are formed. This is because irregularities are formed on the surface of the ceramic body 1 by the film thickness of the external electrode 2. On the other hand, since the pad printing method can print on the uneven surface, the insulating coating 11 can be formed also on the ceramic body 1 on which the external electrodes 2 are formed. Further, in the pad printing method, an insulating coating material having a high viscosity can be adopted, and the insulating coating 11 can be easily formed on the ridgeline portion of the ceramic body 1. In the pad printing method, the size of the insulating coating 11 can be accurately changed by changing the design of the size of the recess 20a of the intaglio 20, and the external electrode 2 and the insulating coating 11 can be prevented from overlapping. .

Next, as shown in FIGS. 8 to 10, the insulating coating 1 is formed on the lower portion of the ceramic body 1 by a pad printing method.
After applying No. 1, it is dried. Next, when glass paste is used as the material of the insulating coating 11, it is fired at a temperature of about 600 ° C. When epoxy-based UV-curable solder resist ink is used, it is irradiated with a high pressure mercury lamp for about 5 minutes. To cure.

Next, as shown in FIG. 1, an electrolytic Ni plating film 3 and then electrolytic Sn (or solder) are formed on the external electrodes 2.
The plating film 4 is formed. These plating films 3 and 4 are used for the external electrodes 2 when the thermistor is soldered to a circuit board or the like.
Protects the solder from scratches. It is not always necessary to form a plating film on the external electrode 2. However, in the case where the plating film is not formed, the metal component of the material of the external electrode 2 is Ag-strong instead of Ag, which is strong against soldering.
It is preferable to employ a Pd alloy.

[Second Embodiment, FIGS. 11 to 14] In the second embodiment, an example in which the insulating coating material has a relatively high viscosity will be described. As shown in FIG. 11, the thermistor includes a ceramic body 31, external electrodes 32 provided on both ends of the ceramic body 31, and a Ni plating film 33 and a Sn plating film 34 provided on the surface of the external electrode 32. And an insulating coating 41 provided on the surface of the ceramic body 31. By forming the insulating coating 41 on the surface of the ceramic body 31 in advance, the plating film is not formed on the portions other than the surface of the external electrode.

Next, a method of manufacturing the thermistor shown in FIG. 11 will be described. A ceramic body 31 subjected to barrel polishing shown in FIG. 12 is prepared. This ceramic body 3
1 is manufactured by the same procedure as the ceramic body 1 of the first embodiment. Insulating film 4 on top of the ceramic body 31
1 is provided. The insulating coating 41 is applied by the pad printing method and then dried. Next, as shown in FIG. 13, the insulating coating 1 is formed on the lower portion of the ceramic body 31 by a pad printing method.
After applying No. 1, it is dried.

Next, as shown in FIG. 14, a conductive paste is applied to both ends of the ceramic body 31 by a dipping method, dried, and then baked at a temperature of about 800 ° C. to form the external electrodes 32. To do. At this time, the insulating coating 11 is also fired at the same time. Next, as shown in FIG. 11, an electrolytic Ni plating film 33 and then an electrolytic Sn plating film 34 are formed on the external electrodes 32.

In the above method, in addition to the effects of the first embodiment, since the insulating coating 41 is also baked when the external electrode 32 is baked, the manufacturing process is simplified and the manufacturing cost is reduced. Can be achieved.

[Other Embodiments] The electronic device and the method for manufacturing the same according to the present invention are not limited to the above embodiments, but can be variously modified within the scope of the invention.

The ceramic body may not be completely covered with the external electrodes and the insulating coating. That is, as shown in FIG. 15, the ceramic body 51 may be exposed between the external electrode 52 and the insulating coating 53. Further, the ceramic body may be a varistor body or the like in addition to the positive characteristic thermistor body and the negative characteristic thermistor body. Furthermore, as an insulating coating made of organic material, epoxy-based U
In addition to the V-curable solder resist ink, a phenol-based ink, an acrylic-based ink, a melamine-based ink, an alkyd-based ink, or a thermosetting ink may be used.

[0024]

As is apparent from the above description, according to the present invention, the surface of the ceramic body is covered with the insulating film made of the inorganic material or the organic material while leaving the external electrodes.
The plating film can be deposited only on the external electrode. When the electronic element is soldered to the circuit board or the like, the insulating coating prevents the soldering flux or the ceramic element body from entering the inside of the ceramic element body, so that the characteristics and reliability of the electronic element are not deteriorated. .

Further, when the insulating coating is formed by the pad printing method, the insulating coating can be formed in the entire area of one main surface and approximately half the areas of the two side surfaces by one printing. Can be reduced. Further, according to the pad printing method, the insulating coating can be surely formed even on the ridgeline portion of the ceramic body, so that the plating film does not deposit on the ridgeline portion and a short circuit defect between the external electrodes may occur. Absent. Further, since the pad printing method can print on the uneven surface, it is possible to form the insulating coating even on the ceramic body on which the external electrodes are formed and the surface is not smooth.

Furthermore, by forming a plating film on the surface of the external electrode, when the electronic element is soldered to a circuit board or the like, the external electrode is protected from being soldered by the plating film, and a highly reliable electronic element is provided. can get.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of an electronic device according to the present invention.

FIG. 2 is a perspective view showing a manufacturing procedure of the electronic device shown in FIG.

FIG. 3 is a perspective view showing a manufacturing procedure following that of FIG. 2;

FIG. 4 is a perspective view showing a manufacturing procedure following that of FIG. 3;

FIG. 5 is a sectional view for explaining a pad printing method.

FIG. 6 is a sectional view for explaining the pad printing method following FIG. 5;

FIG. 7 is a sectional view for explaining the pad printing method following FIG. 6;

FIG. 8 is a perspective view showing a manufacturing procedure following that of FIG. 4;

9 is a sectional view taken along line IX-IX in FIG.

10 is a sectional view taken along line XX of FIG.

FIG. 11 is a sectional view showing a second embodiment of the electronic device according to the present invention.

12 is a perspective view showing a manufacturing procedure of the electronic element shown in FIG.

FIG. 13 is a perspective view showing a manufacturing procedure following that of FIG. 12;

FIG. 14 is a perspective view showing a manufacturing procedure following that of FIG. 13;

FIG. 15 is a cross-sectional view showing another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ceramic element 2 ... External electrode 3,4 ... Plating film 11 ... Insulating film 31 ... Ceramic element 32 ... External electrode 33, 34 ... Plating film 41 ... Insulating film 51 ... Ceramic element 52 ... External electrode 53 ... Insulation Film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01C 17/00 H01C 17/00 A

Claims (9)

[Claims] 1. A ceramic element body having an electrical function, an external electrode provided on the surface of the ceramic element body, and an insulating coating made of an inorganic material or an organic material provided on the surface of the ceramic element body. An electronic device comprising: 2. The electronic element according to claim 1, wherein the ceramic body is either a positive characteristic thermistor element body, a negative characteristic thermistor element body, or a varistor element body. 3. An electronic element comprising: a step of forming external electrodes on the surface of a ceramic body; and a step of forming an insulating coating on the surface of the ceramic body by a pad printing method. Production method. 4. The method of manufacturing an electronic device according to claim 3, wherein after forming an external electrode on the surface of the ceramic body, an insulating coating is formed on the surface of the ceramic body while leaving the external electrode. Method. 5. The external electrode is formed on the surface of the ceramic body after forming an insulating coating on the surface of the ceramic body, leaving a portion where the external electrode is to be formed. Of manufacturing electronic device of. 6. The method of manufacturing an electronic element according to claim 3, wherein a plating film is provided on the surface of the external electrode. 7. The method of manufacturing an electronic element according to claim 3, 4, 5 or 6, wherein the insulating coating is made of an inorganic material or an organic material. 8. The method for manufacturing an electronic element according to claim 3, 4, 5, 6 or 7, wherein the ceramic body has an electric function. 9. The ceramic body is either a positive characteristic thermistor body, a negative characteristic thermistor body or a varistor body, and the ceramic body is characterized in that Manufacturing method of electronic device.