JPH07115003A - Manufacture of chip resistor - Google Patents

Abstract

PURPOSE:To reduce manufacturing cost and enhance dimensional accuracy by forming a resistor or a protection film on one surface of a substrate using gloss ceramic for an insulation substrate and then forming a dividing groove on the other surfaces. CONSTITUTION:A molded body 3 is formed with glass ceramic slurry which includes large particle-sized aluminum powder 1 and small particle-sized aluminum powder 2. Then, the slurry molded body 3 is dried, thereby providing aluminum powder-made green sheets whose filling rates are different from each other. Then, the green sheets 4 are sintered to provide an insulation board which is thermally conductive and anisortropic. An electrode 6 is formed on a higher conductivity surface of the insulation substrate 5 while a resistor 7 is formed thereon and a protection film 8 is further formed. Then, a dividing groove is formed on a lower conductivity surface of the substrate 5 having thermal conductivity anisotropy and divided. Finally, end face electrodes 9 are formed on both sides of chip resistors discretely divided. This construction makes it possible to provide chip resistors excellent in a dissipating performance of heat generated by the discrete resistors 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a chip resistor mainly used in electronic equipment which requires high-density mounting technology.

[0002]

2. Description of the Related Art Conventionally, a sintered 96% by weight alumina substrate having slits for dividing is used as an insulating substrate of a chip resistor, and electrodes, resistors and a protective film are formed on this insulating substrate, and then divided. In this manufacturing method, end face electrodes are formed on both side surfaces.

In the structure of the conventional chip resistor obtained by the above manufacturing method, the heat generated in the resistor of the chip resistor is radiated by the heat transfer from the end face electrodes on both side surfaces to the circuit board. However, there is a limit in using a chip resistor with high power, and there is a problem that the size of the chip resistor must be increased in order to cope with this.

As a method for solving the above-mentioned conventional problems, a structure of a chip resistor has been proposed in which a good heat conductive film is formed in the central portion of the lower surface of the insulating substrate of the chip resistor (Actual exploitation Sho 64). No. 6006).

An example of the structure of the conventional chip resistor provided with the above-described heat dissipation countermeasure will be described below with reference to the drawings.

FIG. 5 is a cross-sectional view of a main part of a structure of a conventional chip resistor provided with a heat dissipation measure.

In FIG. 5, 15 is an insulating substrate, 16 is a resistor, 20 is an electrode, 17 is an end face electrode, 18 is a protective film, 1
9 is a good heat conducting film.

An outline of a conventional method of manufacturing a chip resistor having the above-described structure and being provided with a heat dissipation measure and its structure will be described below.

As the insulating substrate 15 of the chip resistor, a sintered 96 wt% alumina substrate having slits for division is used. On this insulating substrate 15, electrodes 20, resistors 16 and protective film 1 corresponding to a plurality of chip resistors are provided.
8 are formed respectively. Further, a good heat conductive film 19 is formed on the back surface of the insulating substrate 15 on which the resistor 16 is formed.

Thereafter, the chip resistors are divided into individual chip resistors to form end face electrodes 17 on both side faces, and as shown in FIG.
The resistor 16 electrode 20 and the protective film 18 are on the upper surface of the insulating substrate 15, the end face electrodes 17 are on both side surfaces, and the good thermal conductive film 1 is on the lower surface.
9 is to obtain a chip resistor structure in which 9 is formed.

[0011]

However, the structure of the chip resistor as described above has the following problems.

Sintered 96 with slits for division
In the case of using a weight% alumina substrate as an insulating base material,
Since the insulating substrate is highly advanced and the dividing slit cannot be formed after sintering, the dividing slit will be inserted at the green sheet stage, and the dimensional variation of the insulating substrate will occur during sintering, and the chip resistor will be manufactured. Therefore, it is necessary to prepare a large number of electrodes, resistors, and print masks for protective films in consideration of the dimensional variation.

In the structure in which the good thermal conductive film is formed in the central portion of the lower surface of the insulating substrate for improving the heat dissipation of the chip resistor, the good thermal conductive film is soldered when the chip resistor is mounted on the circuit board. It may not be possible to obtain the desired resistance value by contact.

In the structure in which the good thermal conductive film is formed in the center of the lower surface of the insulating substrate, when the chip resistor is used at high power, the thermal conductivity around the resistor is poor and the resistor on the upper surface of the insulating substrate is poor. The heat dissipation of the heat generated in is insufficient.

As a result, in the manufacturing method of the chip resistor, the manufacturing control cost increases due to the dimensional variation of the insulating substrate, and at the same time, the chip resistor due to the heat of the resistor in the structure of the chip resistor. Had a problem such as deterioration in performance.

The present invention has been made in view of the above problems, and an object of the present invention is to manufacture a chip resistor with high dimensional accuracy and to obtain a chip resistor whose performance is highly reliable. It is to provide a method of manufacturing a chip resistor that can be manufactured.

[0017]

The first invention of the present application is, in a method of manufacturing a chip resistor using a glass ceramic as an insulating substrate, a ceramic powder having a first particle diameter, and a ceramic powder having a particle diameter larger than the first particle diameter. A step of preparing a glass-ceramic slurry containing a ceramic powder having a large second particle diameter; a step of forming the glass-ceramic slurry into green sheets having different ceramic powder filling rates in the thickness direction; A step of sintering the green sheet obtained by the step to obtain an insulating substrate having a thermal conductivity anisotropy having a distribution of thermal conductivity in the thickness direction, and an electrode, a resistor and a resistor on the surface of the insulating substrate having high thermal conductivity. The method is characterized by including a step of forming a protective film and a step of forming a dividing groove on a surface of the insulating substrate having low thermal conductivity to divide the insulating substrate into a desired size.

A second invention of the present application is, in a method of manufacturing a chip resistor using a glass ceramic as an insulating substrate, a ceramic powder having a first specific gravity and a ceramic having a second specific gravity which is heavier than the first specific gravity. A step of producing a glass-ceramic slurry containing a powder,
A step of forming a ceramic slurry into a green sheet having a different composition of ceramic powder in the thickness direction; and a step of sintering the green sheet obtained by the above step to obtain a thermal conductivity anisotropy having a distribution of thermal conductivity in the thickness direction. The process of obtaining an insulating substrate, the process of forming an electrode, a resistor, and a protective film on the surface of the insulating substrate having high thermal conductivity, and the step of forming a dividing groove on the surface of the insulating substrate having low thermal conductivity are desired. And a step of dividing into sizes.

[0019]

According to the present invention, glass ceramic is used for the insulating substrate of the chip resistor, and after the resistor and the protective film are formed on one surface of the insulating substrate, the thermal conductivity of the other surface of the insulating substrate is improved. The surface of which the hardness can be relatively low,
It becomes possible to form the dividing groove, and it is possible to reduce the manufacturing management cost of the chip resistor and improve its dimensional accuracy.

Further, an insulating substrate having a heat conduction anisotropy having a distribution of thermal conductivity in the thickness direction is formed on the insulating substrate of the chip resistor, and a resistor is formed on the surface of the insulating substrate having high thermal conductivity. Therefore, even when the chip resistor is used with high power, the heat dissipation of the heat generated by the resistor is good, and the chip resistor with high performance reliability can be realized.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a chip resistor according to an embodiment of the present invention will be described below with reference to the drawings.

1 and 2 are process drawings for explaining a method of manufacturing a chip resistor according to the first embodiment of the present invention.
In FIGS. 1 and 2, 1 is an alumina powder having a large particle diameter, 2 is an alumina powder having a small particle diameter, 3 is a molded body of slurry, 4 is a green sheet, 5 is an insulating substrate having anisotropic heat conduction, and 6 is An electrode, 7 is a resistor, 8 is a protective film, and 9 is an end face electrode.

A method of manufacturing the chip resistor configured as described above will be described below with reference to the drawings. First,
As shown in FIG. 1A, a glass-ceramic slurry containing an alumina powder having a large particle size (for example, an average particle size of 2 μmφ) 1 and an alumina powder having a small particle size (for example, an average particle size of 0.5 μmφ) 2 is prepared. Sheet molding is performed to form a slurry compact 3.

At this time, a lead borosilicate glass powder and an alumina powder (a mixed powder of alumina powder 1 having a large particle diameter and alumina powder 2 having a small particle diameter) were mixed at a weight ratio of 30 to 70, and an organic binder was used. Polyvinyl butyral, di-n-butyl phthalate as a plasticizer, and a mixed solution of toluene and isopropyl alcohol (weight ratio 30:70) as a solvent are mixed to form a slurry, and the slurry is formed into a sheet on an organic film by a doctor blade method. Thus, a slurry compact 3 was obtained.

Next, by drying the molded body 3 of the slurry and volatilizing the solvent in the slurry, an alumina powder 1 having a large particle diameter and an alumina powder 2 having a small particle diameter are obtained as shown in FIG. 1 (b). The green sheets 4 having different alumina powder filling rates were obtained by separating the slurry formed bodies 3 in the thickness direction.

In the step of drying the slurry molded body 3, if auxiliary means such as ultrasonic vibration is also used, the alumina powder 1 having a large particle diameter and the alumina powder 2 having a small particle diameter can be more easily formed in the slurry molded body 3. I was able to separate.

Then, the green sheet 4 was sintered in a belt furnace to obtain an insulating substrate 5 having anisotropic heat conduction as shown in FIG. 1 (c). The sintering condition was 900 ° C. for 1 hour (9
The holding time at 00 ° C is about 10 minutes. ).

In the thus obtained insulating substrate 5 having anisotropic heat conduction, a surface having a high heat conductivity because the alumina powder is highly filled (the heat conductivity when alumina is contained 90% by weight is 0. (04 cal / cm.sec..degree. C.) and the surface thereof has a low thermal conductivity because the alumina powder is less filled than that surface (the thermal conductivity when 50% by weight of alumina is contained is 0.007 cal / cm.sec.). .Degree. C.) and has a distribution of thermal conductivity in the thickness direction. The surface having low thermal conductivity has a low hardness because it contains a large amount of glass, and has a hardness higher than that hardness and can be easily ground by a processing blade having a sharp angle shape.

Then, a predetermined electrode pattern is printed on the high thermal conductivity surface of the insulating substrate 5 having this thermal conductivity anisotropy by using a conductor paste containing silver-palladium as a main component, and then at 850 ° C. The electrode 6 is formed by firing at the firing temperature. Furthermore, a resistor pattern corresponding to the electrode 6 is printed using a resistance paste containing ruthenium oxide as a main component, and then fired at a firing temperature of 850 ° C. to form a resistor 7. Moreover, after printing a protective film pattern corresponding to the resistor 7 using a glass paste containing glass as a main component, the protective film 8 is formed by baking at a baking temperature of 650 ° C. The insulating substrate 5 having the heat conduction anisotropy, on which the electrodes 6, the resistors 7 and the protective film 8 corresponding to the plurality of chip resistors shown in FIG.

Next, a dividing groove for dividing into individual chip resistors is formed on the surface of the insulating substrate 5 having thermal conduction anisotropy having a low thermal conductivity, which is higher in hardness than the hardness thereof and has a sharp angle. After being formed by a processing blade having a shape, it is divided by applying mechanical stress evenly on a rubber plate having elasticity. As a result, the individual chip resistor having a desired size shown in FIG. 1E can be obtained with high dimensional accuracy.

At the time of forming the dividing grooves, a diamond rotary machining blade having the shape of an abacus ball is used to form 0.5-
The surface of the insulating substrate 5 having the thermal conductivity anisotropy was ground while rotating while applying a pressure of 1.0 kg / cm ² . At this time, a dividing groove was formed on the surface of the insulating substrate 5 having heat conduction anisotropy by a rotary working blade to a depth of several microns. The tip of the rotary processing blade was processed to 130 degrees.

Finally, as shown in FIG. 1 (f), the end face electrodes 9 are formed on both side surfaces of the individually divided chip resistor, so that the heat conductivity having the distribution of heat conductivity in the thickness direction shown in FIG. 2 is obtained. A structure of a chip resistor having an insulating substrate 5 having conduction anisotropy, an electrode 6, a resistor 7 and a protective film 8 on its upper surface, and end face electrodes 9 on both side surfaces is obtained.

In the chip resistor structure obtained at this time, since the surface on which the resistor 7 was formed was highly filled with alumina powder, the thermal conductivity was high, and the chip resistor was used at high power. Even in such a case, the heat dissipation of the heat generated by the resistor 7 is improved, and a chip resistor having high performance reliability can be realized.

Although alumina powder was used as the glass-ceramic ceramic powder in this embodiment, any powder having good thermal conductivity such as aluminum nitride or silicon carbide may be used.

A second embodiment of the present invention will be described with reference to FIGS. 3 and 4.

First, as shown in FIG. 3A, a glass-ceramic slurry containing silicon carbide powder 10 and alumina powder 11 is formed into a sheet to form a slurry compact 12.

At this time, a lead borosilicate glass powder and a ceramic powder (mixed powder of silicon carbide powder 10 and alumina powder 11) were mixed in a weight ratio of 50:50, polyvinyl butyral as an organic binder, and dibutyl as a plasticizer. −
N-butyl phthalate and a mixed solution of toluene and isopropyl alcohol (weight ratio of 30:70) as a solvent are mixed to form a slurry, and the slurry is formed into a sheet on an organic film by a doctor blade method to obtain a molded body 12 of the slurry. Obtained.

Next, the slurry compact 12 is dried and the solvent in the slurry is volatilized, so that FIG.
Silicon carbide powder with a low specific gravity as shown in (specific gravity = 3.2)
A green sheet 13 was obtained in which 10 and alumina powder 11 having a large specific gravity (specific gravity = 3.9) 11 were separated in the thickness direction in the slurry molded body 12 due to the difference in specific gravity.

In the step of drying the slurry compact 12, in combination with an auxiliary means such as ultrasonic vibration, the silicon carbide powder 10 having a low specific gravity and the alumina powder 11 having a high specific gravity are more easily separated in the slurry compact 12. did it.

Then, the green sheet 13 was sintered in a belt furnace to obtain an insulating substrate 14 having anisotropic heat conduction as shown in FIG. 3 (c). The sintering condition was 900 ° C. for 1 hour (holding time at 900 ° C. is about 10 minutes).

Insulating substrate 14 having anisotropic heat conduction obtained at this time
In the above, since a large amount of silicon carbide powder 10 having a high thermal conductivity is included, the surface having a high thermal conductivity (the thermal conductivity in the case of including 50% by weight of silicon carbide is 0.1 cal / cm · sec · ° C.).
And a surface having a low thermal conductivity because it contains a large amount of alumina powder 11 having a lower thermal conductivity than the silicon carbide powder 10 (the thermal conductivity in the case of including 50% by weight of alumina is 0.007 cal /
cm · sec · ° C.) and has a thermal conductivity distribution in the thickness direction. Insulating substrate 1 having this heat conduction anisotropy
No. 4 has a low hardness because it contains a large amount of glass, has a hardness higher than that, and can be easily ground by a processing blade having a sharp angled shape.

Then, a predetermined electrode pattern is printed using a conductor paste containing silver-palladium as a main component on the surface of the insulating substrate 14 having the thermal conductivity anisotropy and having high thermal conductivity, and then baked at 850 ° C. The electrode 6 is formed by firing at a temperature. Furthermore, a resistor pattern corresponding to the electrode 6 is printed using a resistance paste containing ruthenium oxide as a main component, and then fired at a firing temperature of 850 ° C. to form a resistor 7. Moreover, after printing a protective film pattern corresponding to the resistor 7 using a glass paste containing glass as a main component, the protective film 8 is formed by baking at a baking temperature of 650 ° C. The insulating substrate 14 having the heat conduction anisotropy, in which the electrodes 6, the resistors 7 and the protective film 8 corresponding to the plurality of chip resistors shown in FIG.

Next, the dividing groove for dividing into the individual chip resistors is formed on the surface of the insulating substrate 14 having the thermal conduction anisotropy having a low thermal conductivity, the hardness being higher than the hardness and having a sharp angle. After being formed by a processing blade having a shape, it is divided by applying mechanical stress evenly on a rubber plate having elasticity. As a result, the individual chip resistors having the desired dimensions shown in FIG. 3E can be obtained with high dimensional accuracy.

At the time of forming the dividing groove, a rotating blade made of diamond having an abacus ball shape is used to form 0.5 to
The surface of the insulating substrate 14 having the thermal conductivity anisotropy was ground while rotating while applying a pressure of 1.0 kg / cm ² . At this time, a dividing groove formed by a rotary working blade could be formed at a depth of several microns on the surface of the insulating substrate 14 having thermal conductivity anisotropy. The tip of the rotary processing blade was processed to 130 degrees.

Finally, as shown in FIG. 3 (f), by forming the end face electrodes 9 on both side faces of the individually divided chip resistors, heat having a heat conductivity distribution in the thickness direction shown in FIG. 4 is formed. A structure of a chip resistor having an insulating substrate 14 having conduction anisotropy, an electrode 6 resistor 7 and a protective film 8 on the upper surface, and end face electrodes 9 on both side surfaces is obtained.

In the structure of the chip resistor thus obtained, the surface on which the resistor 7 is formed contains a large amount of silicon carbide powder 10 having high thermal conductivity, so that the thermal conductivity is high and the chip resistor is high in power. Even in the case of using, the heat dissipation of the heat generated in the resistor 7 is improved, and a chip resistor having high performance reliability can be realized.

Although alumina powder and silicon carbide powder are used as the ceramic powder of glass / ceramic in this embodiment, powders having good thermal conductivity such as aluminum nitride may be combined.

Further, the compounding amount of the ceramic powder, the thermal conductivity and the manufacturing conditions in the first and second embodiments may be any as long as they are within the ranges described in the claims.

[0049]

According to the method of manufacturing a chip resistor of the present invention, the dimensional accuracy can be improved, and the heat dissipation of the heat generated by the resistor is good even when the chip resistor is used at high power. It is possible to obtain a chip resistor having high reliability.

[Brief description of drawings]

FIG. 1 is a process diagram illustrating a method of manufacturing a chip resistor according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of an essential part of the structure of the chip resistor obtained according to the first embodiment of the present invention.

FIG. 3 is a process drawing for explaining the manufacturing method of the chip resistor according to the second embodiment of the present invention.

FIG. 4 is a sectional view of an essential part of the structure of the chip resistor obtained according to the second embodiment of the present invention.

FIG. 5 is a cross-sectional view of a main part of a structure of a conventional chip resistor provided with a heat dissipation measure.

[Explanation of symbols]

 1 Alumina powder having a large particle diameter 2 Alumina powder having a small particle diameter 3, 12 Slurry molded body 4, 13 Green sheet 5, 14 Insulating substrate having heat conduction anisotropy 6 Electrode 7 Resistor 8 Protective film 9 End surface electrode 10 Carbonization Silicon powder 11 Alumina powder

Claims (5)

[Claims] 1. A method of manufacturing a chip resistor using a glass ceramic as an insulating substrate, wherein a ceramic powder having a first particle size and a ceramic powder having a second particle size larger than the first particle size. And a step of forming the glass-ceramic slurry into a green sheet having a different filling rate of ceramic powder in the thickness direction, and sintering the green sheet obtained in the above step. And obtaining a thermally conductive anisotropic insulating substrate having a thermal conductivity distribution in the thickness direction,
A step of forming an electrode, a resistor and a protective film on the surface of the insulating substrate having high thermal conductivity, and a step of forming a dividing groove on the surface of the insulating substrate having low thermal conductivity to divide the insulating substrate into a desired size. A method of manufacturing a chip resistor, comprising: 2. The ceramic powder contains alumina, aluminum nitride or silicon carbide powder.
A method for manufacturing the described chip resistor. 3. A method of manufacturing a chip resistor using glass-ceramic as an insulating substrate, wherein glass containing ceramic powder having a first specific gravity and ceramic powder having a second specific gravity heavier than the first specific gravity. A step of forming a ceramic slurry, a step of forming the glass / ceramic slurry into a green sheet having a different ceramic powder composition in the thickness direction, and a step of sintering the green sheet obtained in the above step in the thickness direction. A step of obtaining an insulating substrate having a thermal conductivity anisotropy having a distribution of thermal conductivity; a step of forming an electrode, a resistor and a protective film on a surface of the insulating substrate having a high thermal conductivity; And a step of forming a dividing groove on the lower surface to divide the insulating substrate into a desired size. 4. A ceramic powder having a first specific gravity is silicon carbide powder, and a ceramic powder having a second specific gravity is alumina powder.
A method for manufacturing the described chip resistor. 5. The chip resistor according to claim 1, wherein the dividing groove is formed by a processing blade having a hardness higher than that of an insulating substrate having anisotropic heat conduction and having a sharp angled shape. Production method.