JP3147134B2 - Chip type thermistor and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type thermistor surface-mounted on a printed circuit board or the like and a method for manufacturing the same. More specifically, the present invention relates to a chip type thermistor which is suitable for a temperature compensating thermistor or a surface temperature measuring sensor of an electronic device and whose resistance value decreases as the temperature rises, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, this type of chip thermistor has
Electrodes mainly composed of silver-palladium are baked on both ends of the thermistor body. The reason for containing palladium in addition to silver in the electrode component is to prevent silver from eluting and disappearing in the solder when soldering the chip thermistor to the substrate, and to obtain solder heat resistance of the electrode. is there.

[0003] However, when the content of palladium is increased, the solder adhesion of the electrodes is reduced, and the bonding strength of the chip type thermistor to the substrate is weakened. Therefore, the content of palladium has a certain limit. Therefore, when electrode soldering is performed at a high temperature for a long time, the conventional chip thermistor still has insufficient solder heat resistance. In order to improve solder heat resistance and solder adhesion, it is conceivable to provide a plating layer on the surface of the base electrode, which is a baked electrode, as in the case of chip type capacitors. Therefore, if plating is performed while exposing the thermistor body, plating will adhere to the surface of the body and the resistance value of the thermistor will differ from the expected value, and the thermistor body will be eroded by the plating solution and the thermistor body will be eroded. Problems such as a decrease in the reliability of the device.

In order to improve this point, the present applicant has developed a chip type thermistor in which the surface of the thermistor body other than the portion where the baked electrode layer contacts is covered with a glass layer and a plating layer is formed on the surface of the baked electrode layer. Patent application (Japanese Unexamined Patent Publication No.
50603). This chip type thermistor is manufactured by the following method. First, an insulating glass layer is formed by printing and firing glass paste on both sides of a ceramic sintered sheet for a thermistor body. Next, after cutting the sintered sheet covered with the glass layer into strips on both sides,
The glass paste is printed and fired on the cut surfaces on both sides in the same manner as described above to form a glass layer. Next, the strip is finely cut in a direction perpendicular to the cut surface to produce a chip. A conductive paste is applied to both ends of the chip so as to cover the cut surface of the chip, and the paste is baked to form a baked electrode layer. Further, a plating layer is formed on the surface using the baked electrode layer as a base electrode to obtain a chip thermistor having a terminal electrode composed of the baked electrode layer and the plated layer.

[0005]

However, a chip thermistor having a structure in which terminal electrodes are generally provided on both side surfaces of a chip thermistor body, including the chip thermistor described above,
Cracks are likely to occur when tensile stress is applied due to thermal stress after surface mounting on a printed circuit board. When cracks occur, the characteristics of the thermistor change. In addition, in the above-described manufacturing method, it is necessary to perform the coating of the glass layer in two separate steps, and after forming the chip, it is necessary to apply a conductive paste to both ends thereof or to form a plating layer. . For this reason, great care must be taken in handling the chips. For these reasons, there has been a problem that the manufacturing process is complicated and the manufacturing cost is necessarily high.

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly reliable chip type thermistor which does not generate solder bridges between electrodes, has excellent solder heat resistance and solder adhesion, has no change in resistance due to electrode plating, and has a high resistance. Is to do. Another object of the present invention is to provide a chip-type thermistor having high strength against tensile stress caused by thermal stress.
Another object of the present invention is to provide a chip thermistor that has no directivity between the front and back sides and facilitates work before mounting on a substrate. Still another object of the present invention is to provide a method for manufacturing a chip-type thermistor capable of manufacturing the above-mentioned excellent chip-type thermistor relatively easily and at low cost.

[0007]

As shown in FIGS. 1 to 3, a first chip-type thermistor 20 of the present invention comprises a chip-shaped thermistor body 11 composed of a hexahedron and a thermistor body 11 formed of the same. a pair of terminal electrodes 12 and 12 spaced along two edges facing each of the lower surface, and a top insulating layer 14 provided on the entire upper surface of the thermistor element 11, the thermistor A lower surface insulating layer 13 is provided between a pair of terminal electrodes 12 on the lower surface of the element body 11.

As shown in FIG . 4 , a second chip type thermistor 30 of the present invention is a chip type thermistor comprising a hexahedron.
The body 11 and the lower surface of the thermistor body 11 are opposed to each other.
A pair of spaced apart along the two edges
A pair of terminal electrodes 32, 32 is provided at intervals along two opposite edges of the terminal electrodes 12, 12 and the upper surface of the thermistor body 11. As shown in FIG.
The third chip-type thermistor 40 of the present invention is different from the first chip-type thermistor 20 in that, instead of the upper surface insulating layer 14 of the thermistor body 11, two opposite edges of the upper surface of the thermistor body 11 are provided. A pair of terminal electrodes 42, 42 are provided at an interval, and an upper surface insulating layer 44 is provided between the terminal electrodes 42, 42. 1 and FIG.
As shown in FIG. 4 and FIG. 5 , the terminal electrodes 12, 32 and 42 are composed of base electrodes 16, 36 and 46 containing a noble metal and the Ni plating layer 1 formed on the surfaces of the base electrodes 16, 36 and 46.
7a, 37a, 47a and the Ni plating layers 17a, 3
It is preferable to include Sn or Sn / Pb plating layers 17b, 37b, 47b formed on the surfaces of 7a, 47a.

Further, the manufacturing method of the first chip-type thermistor 20 of the present invention, the multiple rows of the base electrode 16 is formed on one surface of the thermistor body ceramic sintered sheet 21 shown in FIG. 6 (FIGS. 7 and FIG. 8 ) An insulating paste is applied to one surface of the sintered sheet 21 so as to expose the base electrodes 16 and fill the space between these base electrodes, and after applying the insulating paste to the entire other surface of the sintered sheet 21 , This sintered sheet 21
Is fired to form insulating layers 13 and 14 ( FIG. 9 ), and a Ni plating layer 17a and a Sn or Sn / Pb plating layer 17b are formed in this order on the exposed surface of the underlying electrode 16 to form the underlying electrode 16 and the plating layer. 17 are formed on the sintered sheet ( FIGS. 1 and 10 ) .
Is cut into strips so that each electrode is positioned at the edge of each of two rows of electrodes ( FIG. 11 ), and the strip-shaped thermistor body 22 is cut into chips in a direction perpendicular to the cut surface to obtain a chip-type thermistor. 20 ( FIG. 12 ).

In the second method of manufacturing the chip type thermistor 30 of the present invention, the base electrodes 16 and 36 are formed on both surfaces of the ceramic sintered sheet 21 for the thermistor body shown in FIG. 6 ( FIG. 22 ) . Ni plating layers 17a, 37a and Sn or Sn / Pb plating layers 17b, 37b are formed in this order on the surfaces of the base electrodes 16, 36, respectively, and the electrodes composed of the base electrodes 16, 36 and the plating layers 17, 37 are sintered. The base electrodes 16 and 36 formed on both sides of the sintered sheet and the plating layer 1 were formed on both sides of the sheet ( FIGS. 4 and 23).
A plurality of rows of electrodes are formed so as to face each other on both surfaces of the sintered sheet 21 by grinding each of the electrode faces 7 and 37 into a slit shape. This is a method of obtaining a chip-type thermistor 30 by cutting the strip-shaped thermistor body into chips in a direction perpendicular to the cut surface thereof.

Further, the third method of manufacturing the chip-type thermistor 40 according to the present invention uses a large number of rows of base electrodes 16 and 46 on both surfaces of the ceramic sintered sheet 21 for thermistor body shown in FIG. 24 ( FIG. 24 ), an insulating paste is applied to both surfaces of the sintered sheet 21 so as to expose the base electrodes 16 and 46 and to fill the space between the base electrodes. To form insulating layers 13 and 44 ( FIG. 25 ) .
Ni plating layers 17a, 47a and Sn or Sn / Pb are formed on the surfaces of the underlying electrodes 16, 46 exposed in the same manner as in FIG.
The plating layers 17b and 47b are formed in this order, and a large number of rows of electrodes composed of the base electrodes 16 and 46 and the plating layers 17 and 47 are formed on both sides of the sintered sheet. This is a method of obtaining a chip-type thermistor 40 by cutting the strip-shaped thermistor body into chips in a direction perpendicular to the cut surface so that the electrode is located at the edge.

Hereinafter, the present invention will be described in detail. (A) Manufacturing of First Chip-Type Thermistor 20 : (1) Preparation of Ceramic Sintered Sheet As shown in FIG. 6 , a ceramic sintered sheet 21 for thermistor body is prepared. This sintered sheet 21 is made by the following method. First, Mn, Fe, Co, Ni, Cu, A
One or more metal oxide powders such as 1 are mixed.
When mixing two or more, each metal oxide is weighed so as to have a predetermined metal atomic ratio. The mixture is calcined and pulverized, an organic binder is added and mixed to form a rectangular parallelepiped, and then fired to produce a ceramic sintered block (not shown). Next, this block is cut into a wafer using a band saw, and a sintered sheet 21 shown in FIG. 6 is obtained. After calcination and pulverization of the mixture of metal oxides, an organic binder and a solvent were added and kneaded to prepare a slurry, and the slurry was formed into a film by a doctor blade method and dried to form a green sheet. May be fired to obtain a sintered sheet 21.

(2) Formation of base electrode Next, as shown in FIG.
Conductive paste containing metal powder and inorganic binder applied in stripes
And bake. FIG. 8 is an enlarged view of a portion F in FIG. This coating
The cloth is prepared by superposing a predetermined striped pattern on the sintered sheet 21.
Printing method that prints conductive paste is preferred
No. Examples of noble metal powders include Ag, Au, Pd, and Pt.
And a powder obtained by mixing these.
By this baking, many rows of base electrodes 16 are formed.
Here, a large number of rows of base electrodes are attached to one edge of the sintered sheet 21.
Electrode layer 16a for plating connected to all poles 16 (FIG. 7)
Is preferably formed. In addition, conductive paste
Is applied by a printing method, and is baked to form a baked electrode layer.
In addition to forming the base electrode, the sintered
A fixed stripe pattern is superimposed and a base electrode is formed by thermal spraying.
It can also be formed.

(3) Formation of insulating layer As shown in FIG.
Apply one insulating paste. The insulating paste is a glass paste or a resin paste. The glass component contained in the glass paste or the resin contained in the resin paste needs to have plating resistance. The glass component may be crystalline or non-crystalline. As the resin, a thermosetting resin such as an epoxy resin is exemplified. under
On one side where the ground electrode 16 is provided, the base electrode 16 is exposed.
And paste the insulating paste so as to fill between these electrodes.
Again it is applied in stripes. There is a plating electrode layer 16a
In this case, the electrode layer 16a is also exposed. Base electrode 1
On one side where 6 is not provided, the insulating paste is the entire sheet
Applied to Applying the insulating paste on both sides of the sheet
It is preferable to use a printing method. Apply this insulating paste
After being clothed, the sintered sheet 21 is heat-treated and
Insulating layer 1 made of a glass layer or a resin layer having a thickness of about m
3 and 14 are formed. The insulating layers 13 and 14 are
The coefficient of thermal expansion of the glass layer
40% or more and 100% or less of the thermal expansion coefficient of the sheet 21
Is preferred. When the coefficient of thermal expansion is within this range, the transverse rupture strength of the thermistor 10 is increased as compared with the case where there is no glass layer.

The transverse rupture strength is defined as 2
This refers to the breaking strength when both ends of the chip-type thermistor are placed on one base and stress is applied to the center of the chip-type thermistor. This is a measure of how much the chip-type thermistor can withstand heat due to solder or the like when the surface is mounted on a printed circuit board or stress distortion (thermal stress) generated by a thermal cycle after mounting. The bending strength of the thermistor 20 having the glass layer of the present invention is increased by
It is considered that the compressive stress remains in the glass layer on the surface of the thermistor body. That is, when the thermistor body 11 and the glass layers 13 and 14 that have been thermally expanded at the time of manufacturing cool down, the thermistor body having a large thermal expansion coefficient shrinks more and the glass layer is in a compressed state. Thermistor in this state
When a bending force is applied to 20 , a compressive stress is generated inside the bend and a tensile stress is generated outside the bend. Both the thermistor body and the glass layer are characterized by being strong in compressive stress and weak in tensile stress. For this reason, if a compressive stress is applied in advance by the glass layer, cracks are less likely to occur when a bending force is applied to the tensile stress outside the bend as compared to a case where no glass layer is provided. The resin layer does not have the effect of increasing the bending strength of the thermistor, but has the advantage of being formed by curing at a lower heat treatment temperature than the glass layer.

(4) Formation of Plating Layer As shown in FIG. 1 and FIG.
A plating layer 17 is provided on the surface,
Preferably, layer 17 creates multiple rows of electrodes. Me
The layer 17 is composed of a Ni plating layer 17a and Sn or Sn / Pb.
The plating layer 17b is formed in this order. These plating layers are formed by electrolytic plating. Plating bath is Ni, Sn
Alternatively, known Sn / Pb is used for each. The reason why the plating layer has a double structure is to improve the solder heat resistance by the Ni plating layer 17a and to prevent the electrode of the base electrode 16 from being eroded by solder, and to use Sn or Sn / Pb.
This is for improving the solder adhesion of the terminal electrode 12 by the plating layer 17b.

(5) Formation of Strip-shaped Thermistor Element As shown in FIGS. 10 and 11 , the sintered sheet 21 on which the plating layer 17 is formed at the position of the arrow M is formed by arranging two rows of electrodes at the edges. It is cut into strips by a dicing saw such as a cutting machine with a diamond blade so as to be located, and a strip-shaped thermistor body 22 is obtained.

(6) Production of Chip Thermistor As shown in FIGS. 11 and 12 , the above-mentioned dicing saw is used to cut the strip thermistor body 22 into chips in a direction perpendicular to the cut surface of the strip-shaped thermistor body 22 at the location indicated by the arrow N. Thus, a chip type thermistor 20 is obtained. Chip type thermistor 2 obtained in FIG.
By turning over 0, the chip type thermistor shown in FIGS. 1 and 3 is obtained.

(7) Fabrication of First Chip-Type Thermistor with Other Structure As shown in FIG. 13 , a plurality of base electrodes 26 are formed on one surface of the sintered sheet 21 in a tooth shape. One unit of the electrode layer 26 includes an electrode portion 26a and a connection portion 26b. After forming the above-mentioned plating layer, the sintered sheet 21 is cut as shown by a broken line R in FIG. 14 to obtain a chip type thermistor 28 shown in FIGS. 16 to 18 . The thermistor 28 has a smaller exposed portion of the electrode layer 26 than the thermistor 20 and is less susceptible to ion migration. Also, when cutting the sintered sheet 21 as indicated by a broken line S in FIG. 15, FIG. 1
9 to 21 are obtained.
Since the thermistor 29 has no exposed portion of the electrode layer 26, it is hardly affected by ion movement. However, as shown in FIG.
The portion indicated by the symbol T in which the fifteen connection portions 26b are continuous is discarded. 16 to 21 , the same reference numerals as those in FIGS. 2 and 3 indicate the same components.

(B) Manufacturing of the Second Chip Thermistor 30: (1) Preparation of Ceramic Sintered Sheet and Formation of Base Electrode Ceramic sintering is performed by the same manufacturing method as the ceramic sintered sheet of the first chip thermistor 20. The sheet 21 is manufactured. Next, as shown in FIG.
The same conductive paste as the conductive paste of the chip type thermistor 20 is similarly applied and baked. By this firing, base electrodes 16 and 36 are formed on both surfaces of sintered sheet 21.

(2) Formation of Plating Layer As shown in FIGS. 4 and 23 , plating layers 17 and 37 are provided on the surfaces of the base electrodes 16 and 36, respectively.
It is preferable to form an electrode by the plating layer 17, the base electrode 36, and the plating layer 37. Plating layers 17 and 37 are N
The i-plated layers 17a and 37a and the Sn or Sn / Pb plated layers 17b and 37b are formed in this order. These plating layers are formed similarly to the plating layers of the first chip type thermistor 20 .

[0022] (3) multiple rows of electrodes, the strip-like thermistor body and the diamond blade base electrode 16 and the plating layer 17 and the base electrode 36 and the plating layer 37 of the code B portion of the chip-type thermistor formation Figure 23
A large number of electrodes are formed on both surfaces of the sintered sheet 21 so as to face each other by grinding in a slit shape using a dicing saw such as a cutting machine with a cutting machine . Although not shown , concave stripes are formed on both surfaces between the electrodes in many rows by this grinding. This concave stripe forms a gap between the terminal electrodes of the chip thermistor 30 as a final product. The sintered sheet 21 having the concave stripes is cut into strips such that each electrode is positioned at the edge of each of two rows of electrodes, thereby obtaining a strip-shaped thermistor body. FIG. 4 is a sectional view of the strip-shaped thermistor body cut into chips in a direction perpendicular to the cut surface .
Is obtained. This thermistor 30 has the same shape on both sides.

(C) Manufacturing of Third Chip-Type Thermistor 40: (1) Preparation of Ceramic Sintered Sheet and Formation of Base Electrode Ceramic sintering is performed in the same manufacturing method as the ceramic sintered sheet of first chip-type thermistor 20. The sheet 21 is manufactured. Next, as shown in FIG.
The same conductive paste as that of the chip type thermistor 20 is applied in stripes. This stripe is a sintered sheet 21
Are applied so as to face each other on both sides, and then fired. By this firing, the underlying electrodes 16 and 46 facing each other are formed on both surfaces of the sintered sheet 21.

(2) Formation of Insulating Layer As shown in FIG. 25 , the same insulating paste is applied on both surfaces of the sintered sheet 21 to the first chip type thermistor 20 respectively.
Apply in the same manner as in This insulating paste is the same as the insulating paste of the first chip type thermistor 20 , and is a glass paste or a resin paste. On one surface where the base electrode 16 is provided, the base electrode 16 is exposed and the space between these electrodes is filled. On the one surface where the base electrode 46 is provided, the base electrode 46 is exposed and the space between these electrodes is filled. As described above, the insulating paste is applied in stripes. When the same plating electrode layer (not shown) as the plating electrode layer 16a shown in FIG. 7 is provided on both surfaces of the sheet, these plating electrode layers are also exposed. After applying the insulating paste, the sintered sheet 21 is heat-treated to
The insulating layers 13 and 44 made of a glass layer or a resin layer having a thickness of about 0 to 20 μm are formed. When the insulating layers 13 and 44 are glass layers, the thermal expansion coefficient of the glass layer is 40% or more and 100% or more of the thermal expansion coefficient of the sintered sheet 21 for the thermistor element body for the same reason as the glass layer of the first chip type thermistor 20. The following is preferred.

(2) Formation of Plating Layer Similar to the formation of the electrodes of the first chip type thermistor 20 shown in FIG. 10 , plating layers 17 and 47 are provided on the respective surfaces of the base electrodes 16 and 46, and And plating layer 17
It is preferable to form a large number of rows of electrodes with the base electrode 46 and the plating layer 47. As shown in FIG.
7, 47 are Ni plating layers 17a, 47a and Sn or S
The n / Pb plating layers 17b and 47b are formed in this order.
These plating layers are formed similarly to the plating layers of the first chip type thermistor 20.

(3) Formation of strip-shaped thermistor body and chip-type thermistor The first chip-type thermistor 2 shown in FIGS. 10 and 11
The sintered sheet 21 on which the plating layers 17 and 47 are formed in the same manner as the formation of the electrode No. 0 is cut into strips so that each electrode is positioned at the edge of each of the two rows of electrodes, thereby obtaining a strip-shaped thermistor body. The chip thermistor 40 shown in FIG. 5 is cut into chips in a direction perpendicular to the cut surface of the strip-shaped thermistor body .
Get. The thermistor 40 has the same shape on both sides.

(D) Fabrication of Chip Thermistor with Insulating Coating As shown in FIG. 27 , with respect to the first chip thermistor 20, other than the lower surface of the thermistor body 11 having a pair of terminal electrodes 12, 12. The insulating film 50 may be formed on five surfaces. The film 50 is formed by forming the thermistor body 1 having a pair of terminal electrodes 12, 12 as shown in FIG.
This is performed by attaching the lower surface of 1 to a resin sheet or film 50a and masking, and then performing chemical vapor deposition of the resin. In FIG. 26 , reference symbol P indicates a spray line at the time of chemical vapor deposition. As a resin suitable for the chemical vapor deposition, a polyparaxylylene resin (trade name: parylene resin, manufactured by Union Carbide Co., Ltd.) may be mentioned. Note that a heat treatment may be performed after applying and drying a thermosetting resin instead of the chemical vapor deposition.

[0028]

As shown in FIG . 3 , a chip type thermistor 20 is surface-mounted on a printed circuit board 24 by soldering. At this time, solder heat resistance is improved by the Ni plating layer 17a, electrode erosion of the base electrode 16 by solder is prevented, and solder adhesion of the terminal electrode 12 is improved by the Sn or Sn / Pb plating layer 17b. Since these plating layers 17 cover the surface of the noble metal base electrode 16, ion migration of the noble metal hardly occurs.
The same applies to the chip type thermistors 28, 29, 30 or 40. In the case of the chip type thermistor 20, 28, 29 or 40, the insulating layer 1 is provided between a pair of base electrodes 16, 16, 26, 26 or 46, 46 on the lower surface of the thermistor body 11.
Since the thermistor body is not exposed when the plating layer is formed, plating does not adhere to the surface of the body, and the thermistor body is not eroded by the plating solution. It does not change with respect to the expected value. Second, no solder bridge is formed between the electrodes when soldering to the substrate. Chip type thermistors 20, 28,
29 or 40, when the insulating layer 13, 14, or 44 is a glass layer, the bending strength of the thermistor is improved, and the durability against thermal stress is high.

[0029]

As described above, the conventional manufacturing method requires a large number of steps and is complicated. However, according to the manufacturing method of the present invention, a chip-type thermistor can be manufactured relatively easily with a small number of steps. Therefore, it is suitable for mass production and the manufacturing cost is reduced. In particular, by precisely cutting the thermistor body after forming the base electrode and plating layer, the dimensions of the element, the electrode area, etc. can be strictly controlled, so no special processing is required after forming the chip In addition, a chip thermistor having a high resistance value can be obtained. Further, by forming a plating layer on the surface of the base electrode, a highly reliable thermistor having excellent solder heat resistance and solder adhesion can be obtained.

In particular, like the first and third chip-type thermistors of the present invention, the lower surface of the thermistor body facing the printed circuit board except for the portion where the pair of terminal electrodes is in contact is covered with an insulating layer. In addition, solder bridges are not generated, and ion migration hardly occurs. If the insulating layers of the first and third chip-type thermistors are formed of glass layers, the strength against tensile stress caused by thermal stress after mounting on the substrate is high. Further, if the front and back surfaces are the same, as in the second and third chip thermistors of the present invention, the work before mounting on the substrate can be facilitated and the assembling cost of the thermistor can be reduced. Further, if an insulating coating is formed on the other five surfaces of the first chip type thermistor except the lower surface of the thermistor body having a terminal electrode, ion migration is more difficult to occur, and unexpected external force is applied to the thermistor. However, there is an advantage that the characteristics are not changed even if the element body is not chipped and the conductive substance adheres to the side surface of the thermistor element body where the insulating layer is not provided.

[0031]

EXAMPLES Next, the present invention will be described based on examples to show specific embodiments of the present invention. The embodiments described below do not limit the technical scope of the present invention. Example 1 A first chip type thermistor shown in FIGS. 1 to 3 was manufactured by the following method. First, a commercially available manganese compound, nickel compound, and cobalt compound are used as starting materials, and these are converted into MnO ₂ : NiO: CoO to have a metal atomic ratio of 3:
Each was weighed at a ratio of 1: 2. The weighed product was uniformly mixed by a ball mill for 16 hours and then dehydrated and dried. Next, the mixture was calcined at 900 ° C. for 2 hours, and the calcined product was again pulverized by a ball mill and dehydrated and dried. After adding an organic binder to the pulverized material and mixing uniformly, the mixture was compression-molded into a rectangular parallelepiped. This compression molded product was fired at 1200 ° C. for 4 hours under atmospheric pressure, and was about 35 mm long, about 50 mm wide, and about 1 mm thick.
A 0 mm ceramic sintered block (not shown) was produced. Next, this block was cut into a wafer shape using a band saw to obtain a sintered sheet 21 having a length of about 35 mm, a width of about 50 mm, and a thickness of about 0.5 mm shown in FIG.

Next, as shown in FIG. 7 and FIG.
Conductivity containing noble metal powder and inorganic binder on one side of sheet 21
The paste was applied in stripes by a printing method. The conductive paste is a commercially available silver paste, comprising Ag powder, glass fine particles, and an organic vehicle. The thermistor body coated with the conductive paste is dried under atmospheric pressure, and then dried at 30 ° C. /
The temperature is raised to 820 ° C. at a rate of 10 minutes, held there for 10 minutes, and the temperature is lowered to room temperature at a rate of 30 ° C./minute to be made of Ag.
Base electrodes 16 of a large number of firing electrodes were formed. Electrode 1
6 had the same width, and the electrodes were equally spaced.
The width of one electrode is about 0.7 mm, and between the electrodes
The separation was about 0.4 mm. One end of the sintered sheet 21
A plating electrode connected to all of the rows of base electrodes 16 on the edge
The pole layer 16a was formed.

As shown in FIG . 9, both sides of the sintered sheet 21
Printing paste containing the same crystallized glass
Was applied. Fill the space between the base electrodes 16 with a glass pace
When applying the coating, the opposite ends of the base electrode 16
It was applied to cover the edge. After application, the sintered sheet 21 is fired.
To form glass layers 13 and 14 having a thickness of about 15 μm.
Was. The thermal expansion coefficients of these glass layers 13 and 14 are 68 ×
10 ⁻⁷ / ° C., and the coefficient of thermal expansion of the sintered sheet 21 is 85
^Less than × 10 ^-7 / ° C. The plating electrode layer 16a
To the base electrode 16 by electrolytic plating.
Formed a Ni plating layer 17a of 1-2 μm thickness on the surface of
Then, on top of this, Sn plating, also having a thickness of 3 to 6 μm, is formed.
A layer 17b was formed (FIGS. 1 and 3) .

As shown in FIG . 10 to FIG.
The sintered sheet 21 on which the plating layer 17 is formed is
Position the electrodes so that each electrode is positioned at the edge
Cut into strips with a cutting machine equipped with
After obtaining the body 22, using the same cutting machine at the point of the arrow N
In a direction perpendicular to the cut surface of the strip-shaped thermistor body 22,
Width W = about 0.5 mm, length shown in FIG.
Chip type with length L = about 1.0mm and thickness T = about 0.5mm
The thermistor 20 was obtained. This chip type thermistor 20
The terminal electrodes 12, 12 are turned over as shown in FIG.
Attached to a printed circuit board 24 by solder 23
You.

<Comparative Example 1> A conductive electrode containing 80% Ag and 20% Pd was baked at 850 ° C. without providing a Ni plating layer and a Sn plating layer to form a terminal electrode using only a baked electrode layer made of silver-palladium. did. Otherwise in the same manner as in Example 1, the lower surface Gala
Type thermistor having a glass layer 13 and a top glass layer 14
A star was made.

<Comparative Tests and Results> Solder Adhesion Thermistors of Example 1 and Comparative Example 1 were replaced by 300.
Each sample was prepared and immersed in a eutectic solder (H60-A) containing Ag melted at a temperature of 230 ° C. for 4 seconds with tweezers sandwiching the sample, and the solder adhesion area of the terminal electrode was examined with an optical microscope. . Table 1 shows the results. Solder heat resistance Thermistors of Example 1 and Comparative Example 1 were 300
Each sample was prepared and immersed in a eutectic solder (H60-A) bath containing Ag melted at a temperature of 350 ° C. with tweezers for 30 seconds with tweezers, and the disappearance of the terminal electrode was examined with an optical microscope. Table 1 shows the results.

[0037]

[Table 1]

As is clear from Table 1, the thermistor of Example 1 was superior to Comparative Example 1 in solder adhesion and solder heat resistance .

[Brief description of the drawings]

FIG. 1 is an external perspective view of a first chip type thermistor of the present invention .
FIG.

FIG. 2 is a bottom view thereof.

FIG. 3 is a sectional view taken along line A′-A ′ of FIG . 2;

FIG. 4 is an external perspective view of a second chip type thermistor of the present invention .
FIG.

FIG. 5 is an external perspective view of a third chip thermistor of the present invention .
FIG.

FIG. 6 shows a thermistor body of the chip type thermistor of the present invention .
FIG. 1 is an external perspective view of a ceramic sintered sheet to be used.

FIG. 7 shows the sintered sheet for the first chip type thermistor
Perspective view the base electrode is made form multiple rows on one side of the.

FIG. 8 is an enlarged perspective view of a portion F in FIG . 7;

FIG. 9 is a diagram showing a space between base electrodes on one surface of the sintered sheet of FIG .
FIG. 4 is a perspective view in which an insulating layer is formed on the entire other surface.

FIG. 10 shows a plating layer on the surface of the exposed underlying electrode of FIG .
The formed perspective view.

11 is a perspective view of the sintered sheet of FIG . 10 cut into a strip shape.
FIG.

FIG. 12 shows a strip-shaped thermistor body of FIG .
FIG.

FIG. 13: Under another first chip thermistor of the present invention
The perspective view corresponding to FIG. 8 which shows a ground electrode.

FIG. 14 is a cut of a sintered sheet having the base electrode of FIG . 13;
The principal part top view which shows a situation.

FIG. 15 shows another sintered sheet having the base electrode of FIG .
The principal part top view which shows the cutting situation.

FIG. 16 shows a chip cut by the method shown in FIG .
FIG.

FIG. 17 is a sectional view taken along line BB of FIG . 16;

FIG. 18 is a sectional view taken along line CC of FIG . 16;

FIG. 19 is a view showing a chip manufactured by the method shown in FIG .
FIG.

FIG. 20 is a sectional view taken along line DD of FIG . 19;

FIG. 21 is a sectional view taken along line EE of FIG . 19;

FIG. 22 shows the sintered sheet for a second chip type thermistor.
FIG. 4 is a perspective view in which a base electrode is formed on both surfaces of the substrate.

FIG. 23 shows surfaces of base electrodes on both surfaces of the sintered sheet of FIG . 22;
The perspective view in which the plating layer was formed in FIG.

FIG. 24 shows the sintered sheet for a third chip type thermistor.
FIG. 3 is a perspective view in which a large number of rows of base electrodes are formed on both surfaces of the substrate.

FIG. 25 is a diagram showing a condition between base electrodes on both surfaces of the sintered sheet of FIG . 24;
The perspective view in which the edge layer was formed.

FIG. 26 is a thermistor body for a first chip type thermistor;
Insulating film is formed on 5 surfaces other than the terminal electrode forming surface
FIG.

FIG. 27 is a first chip type having the insulating film formed thereon .
Sectional drawing corresponding to FIG. 3 of a thermistor.

[Description of Signs] 20 , 28 , 29, 30, 40 Chip type thermistor 11 Thermistor body 12, 32, 42 Terminal electrode 13 Lower surface insulating layer 14, 44 Upper surface insulating layer 16, 26, 36, 46 Base electrodes 17, 37 , 47 plating layer 17a, 37a, 47a Ni plating layer 17b, 37b, 47b Sn or Sn / Pb plating layer 21 ceramic sintered sheet 22 strip-shaped thermistor element 50 insulating coating

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-33401 (JP, A) JP-A-3-250603 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01C 7/04 H01C 1/14 H01C 17/06

Claims (10)

(57) [Claims] 1. A chip-shaped thermistor element comprising a hexahedron
(11), and a pair of terminal electrodes (12, 1) provided at intervals along two opposing edges on the lower surface of the thermistor body (11).
2) and another pair of terminal electrodes (3) provided at intervals along two opposing edges on the upper surface of the thermistor body (11).
2, 32). 2. A lower surface insulating layer (13) is provided between a pair of terminal electrodes (12, 12) on a lower surface of the thermistor body (11), and another pair of terminals on an upper surface of the thermistor body (11). electrodes (42,42) thermistor chips of claim 1, wherein the upper surface insulating layer (44) is provided between. 3. A base electrode containing a noble metal, wherein the terminal electrode (12, 42) includes a noble metal.
Pole (16,46) and the surface of this underlying electrode (16,46)
Ni plating layer (17a, 47a) and this Ni plating layer (17a, 47a)
Sn or Sn / Pb plating layer (17b, 4b) formed on the surface of
A 7b), the Ni plating layer (17a, 47a) and Sn or Sn / Pb plating layer (17b, 47b) surface area is smaller than the surface area of the underlying electrode (16, 46) of the lower surface insulating layer ( 3. The chip type thermistor according to claim 2, wherein (13) is provided on the entire lower surface of the thermistor body (11) except for the Ni plating layer (17a) and the Sn or Sn / Pb plating layer (17b). 4. A terminal electrode (12, 42) comprising a noble metal-containing base electrode.
Pole (16,46) and the surface of this underlying electrode (16,46)
Ni plating layer (17a, 47a) and this Ni plating layer (17a, 47a)
Sn or Sn / Pb plating layer (17b, 4b) formed on the surface of
A 7b), the Ni plating layer (17a, 47a) and Sn or Sn / Pb plating layer (17b, 47b) surface area is smaller than the surface area of the underlying electrode (16, 46) of the lower surface insulating layer ( 13) is provided on the entire lower surface of the thermistor body (11) except for the Ni plating layer (17a) and the Sn or Sn / Pb plating layer (17b);
(44) is the Ni plating layer (47a) and Sn or Sn / Pb
The chip thermistor according to claim 2, which is provided on the entire upper surface of the thermistor body (11) except for the plating layer (47b). 5. An upper insulating layer (14, 44) or a lower insulating layer (13).
The chip thermistor according to claim 2 , wherein is a synthetic resin layer. 6. The other 5 excluding the lower surface of the thermistor body (11).
3. The chip thermistor according to claim 1, wherein an insulating film (50) is provided on the surface. (H) forming a plurality of rows of base electrodes (16) on one side of a ceramic sintered sheet (21) for a thermistor element; (i) exposing the base electrodes (16) and Base electrode (16,1
6) a step of applying an insulating paste to one side of the sintered sheet (21) so as to fill the gap, and (j) the insulating property is applied to the entire other side of the sintered sheet (21) in the step (i). A step of applying a paste; and (k) firing the sintered sheet (21) of the step (j) to form an insulating layer (1).
Forming a Ni plating layer (1) on the exposed surface of the underlying electrode (16).
7a) and a step of forming a Sn or Sn / Pb plating layer (17b) in this order to form a large number of rows of electrodes composed of the base electrode (16) and the plating layer (17) on the sintered sheet (21). (M) a step of cutting the sintered sheet (21) having the multiple rows of electrodes into strips so that each row of electrodes is positioned at an edge, and (n) the strip thermistor. The element body (22) is cut into chips in a direction perpendicular to the cut surface, and the chip-shaped thermistor element body (1
A chip thermistor (2) having a pair of terminal electrodes (12, 12) spaced along two opposing edges on the lower surface of (1).
0). A method for manufacturing a chip-type thermistor, comprising: 8. A ceramic sintered body for a thermistor body.
Forming a base electrode (16) on one entire surface of the sheet (21); and (o) a sintered sheet on which the base electrode (16) is formed in the step (a).
(21) a step of forming another base electrode (36) on another entire surface of the base, (p) a Ni plating layer (17a, 37) on the surface of the base electrode (16, 36).
a) and a step of forming Sn or Sn / Pb plating layers (17b, 37b) in this order, respectively; (q) base electrodes (16, 36) formed on both surfaces of the sintered sheet;
Forming a plurality of rows of electrodes so as to face each other on both surfaces of the sintered sheet (21) by grinding each of the electrode surfaces comprising the plating layer (17, 37) into a slit shape, and (r) the plurality of electrodes. Cutting the sintered sheet (21) having the rows of electrodes into strips so that each row of electrodes is positioned at an edge, and (s) cutting the strip-shaped thermistor body with its cut surface. Two sets of terminal electrodes (12,12,12,12) are cut in a vertical direction into chips and spaced along two opposing edges of the upper and lower surfaces of the chip-like thermistor body (11). Obtaining a chip-type thermistor (30) having (32, 32). 9. (t) In the step (h), multiple rows of base electrodes (1) are formed.
6) On another side of the sintered sheet (21) formed with the base electrode
(16) forming a plurality of rows of base electrodes (46) so as to face each other; (u) exposing the base electrodes (16, 46) and forming the base electrodes (1).
6,16,46,46) applying an insulating paste on both sides of the sintered sheet (21) so as to fill in the gap, (v) firing the sintered sheet (21) and insulating layer (13 (W) forming a Ni plating layer (17a, 47a) and a Sn or Sn / Pb plating layer (17b, 47b) on the exposed surface of the underlying electrode (16, 46).
Are formed in this order, and the base sheet (16, 46) and a plurality of rows of electrodes comprising a plating layer (17, 47) are formed on the sintered sheet.
(X) a step of cutting the sintered sheet (21) on which the multiple rows of electrodes are formed into strips such that each electrode is positioned at the edge of each of the two rows of electrodes; (Y) cutting the strip-shaped thermistor body into chips in a direction perpendicular to the cut surface thereof along the two opposing edges of the upper surface and the lower surface of the chip-shaped thermistor body (11), respectively; Obtaining a chip-type thermistor (40) having two pairs of terminal electrodes (12, 12, 42, 42) at intervals. 10. A pre-SL (n) step, forming (s) is after the step or (y) step, (z) other five surfaces an insulating film except the lower surface of the thermistor element (11) (50) 10. The method according to claim 7 , further comprising the step of:
The method for manufacturing a chip-type thermistor according to the above.