JP2007012908A - Chip resistor and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve corrosion resistance such as migration resistance etc. by forming on the upper surface of a chip-type insulating substrate a resistor film and upper surface electrodes for both ends thereof, and by reducing the level difference between the upper surface of the overcoat for the resistor film and both upper surfaces on the right-hand and left-hand sides thereof. <P>SOLUTION: A cover coat 6 is formed on the upper surfaces of the upper surface electrodes, and the overcoat is formed on the part of the upper surface of the cover coat excluding both extension parts thereof. Second auxiliary upper surface electrodes covering these extensions are formed on the upper surfaces of the both extensions of the cover coat, so that parts of the second auxiliary upper surface electrodes 8 are superposed on and bonded to first auxiliary upper surface electrodes at the right-hand outside and left-hand outside of the extensions, and parts of the second auxiliary upper surface electrodes are superposed on the end parts of the overcoat. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a chip resistor in which at least one resistive film, terminal electrodes for both ends thereof, and an overcoat covering the resistive film are formed on a chip-shaped insulating substrate, and the chip resistor is manufactured. It is about how to do.

  Conventionally, this type of chip resistor has a configuration in which the overcoat covering the resistive film protrudes high at the center of the insulating substrate and has a large step. When adsorbing with a collet, there were problems such as inability to adsorb or cracks in the overcoat.

  In addition to this, the upper surface electrode formed on the upper surface of the insulating substrate of both terminal electrodes to both ends of the resistance film to be electrically connected to the resistance film is a conductive material mainly composed of silver having a small electric resistance. By forming a thin film with paste, this upper surface electrode has a metal plating layer for soldering on the surface of the upper surface electrode. There is a problem that the upper electrode is disconnected because the sulfur component causes corrosion such as magnation so that silver is converted to silver sulfide by the sulfur gas.

Therefore, in conventional chip resistors, for example, as described in Patent Documents 1 and 2, as described above, silver is removed from the upper surface electrode formed of a conductive paste mainly composed of silver. The auxiliary upper surface electrode made of a conductive paste made of metal is formed so as to be partially overlapped with the overcoat, thereby eliminating or reducing the level difference and corroding the upper surface electrode such as sulfidation. It is configured to suppress this.
JP-A-8-236302 JP 2002-184602 A

  In the conventional chip resistor described above, as described in both patent documents, the portion where the auxiliary upper surface electrode overlaps the cover coat is located directly above the upper surface electrode made of silver-based conductive paste. It is a structure that

  In this case, even if the auxiliary upper surface electrode covering the upper surface electrode has a conductive paste made of a metal other than silver, such as nickel, the auxiliary upper surface electrode is completely applied to the carver coat of different materials. As a result, the portion of the auxiliary upper surface electrode that overlaps the overcoat peels off from the overcoat, or the portion that overlaps the overcoat often cracks.

  Therefore, if the portion where the auxiliary upper surface electrode overlaps the cover coat is positioned directly above the upper surface electrode, peeling or cracking may occur in the portion of the auxiliary upper surface electrode overlapping the overcoat. When this occurs, the atmospheric air immediately penetrates to the upper surface electrode below the upper surface electrode, so that corrosion such as magnetization occurs on the upper surface electrode due to sulfur components in the atmospheric air.

  In other words, the conventional structure has a problem that the upper surface electrode has a low effect of preventing corrosion such as mag- lation, and in other words, has low corrosion resistance such as mag- lation resistance.

  It is a technical object of the present invention to provide a chip resistor that can reliably improve corrosion resistance such as mag- lation resistance and a manufacturing method thereof.

In order to achieve this technical problem, the chip resistor according to the present invention is, as described in claim 1, “at least one resistive film and upper electrodes for both ends thereof are formed on the upper surface of a chip-shaped insulating substrate. In the chip resistor consisting of
A first auxiliary upper surface electrode is formed on the upper surfaces of the upper surface electrodes so as to cover the entire upper surface electrode, and a cover coat covering the upper surface of the resistance film is formed on both ends of the cover coat. An extension portion is formed integrally so as to cover only the portion overlapping the upper surface electrode without covering the left and right outer sides of the upper surface of the first auxiliary upper surface electrode, and the upper surface of the cover coat An overcoat that covers the cover coat is formed on a portion excluding the two extension portions, and a second auxiliary upper surface electrode that covers the extension portion is formed on the upper surface of the two extension portions of the cover coat. A part of the upper surface electrode overlaps and is joined to the first auxiliary upper surface electrode on the left and right outer sides of the extension, and a part of the second auxiliary upper surface electrode overlaps the end of the overcoat. Furthermore, side electrodes are formed on both left and right end surfaces of the insulating substrate so that a part of the side electrodes overlaps a part of the upper surface of the second auxiliary upper surface electrode, and the second auxiliary upper surface electrode is formed. A metal plating layer is formed on the surface of the side electrode. "
It is characterized by that.

Further, the manufacturing method of the present invention, as described in claim 4,
“A step of forming at least one resistive film and upper surface electrodes on both ends of the upper surface of the chip-shaped insulating substrate;
Forming a first auxiliary upper surface electrode on the upper surfaces of the upper surface electrodes so as to cover the entire upper surface electrode; and a cover coat for covering the upper surface of the resistance film. A step of integrally forming at both ends an extension that covers only the portion overlapping the upper surface electrode without covering the left and right outer sides of the upper surface of the first auxiliary upper surface electrode;
Forming an overcoat covering the cover coat on a portion of the upper surface of the cover coat excluding the two extension portions;
A second auxiliary upper surface electrode covering the extension portion is bonded to the upper surfaces of both extension portions of the cover coat, and a part of the second auxiliary upper surface electrode is overlapped and joined to the first auxiliary upper surface electrode on the left and right sides of the extension portion. And forming a part of the second auxiliary upper surface electrode so as to overlap an end of the overcoat;
Forming side electrodes on left and right end surfaces of the insulating substrate such that a part of the side electrodes overlaps a part of the upper surface of the second auxiliary upper surface electrode;
Forming a metal plating layer on the surfaces of the second auxiliary upper surface electrode and the side electrode;
It has. "
It is characterized by that.

  With the above-described configuration, the side electrode and the metal plating layer can be electrically connected to the upper surface electrode through the second auxiliary upper surface electrode and the first auxiliary upper surface electrode, and the electrical conductivity can be reliably exceeded. Under the condition that the step between the upper surface of the coat and the upper surface portions on the left and right sides can be reduced or eliminated, the entire upper surface electrode is connected to the second auxiliary upper surface electrode and the first auxiliary upper surface electrode. , Can be covered in triplicate with the extension of the cover coat in between.

  Therefore, even if peeling or cracking occurs in the portion of the second auxiliary upper surface electrode that overlaps the end portion of the overcoat, the atmospheric air penetrates into the upper surface electrode. Since it can be reliably prevented by the extension part of the cover coat, the corrosion resistance such as magnation can be greatly improved.

  In this case, as described in claim 2, by forming at least the second auxiliary upper surface electrode of the first auxiliary upper surface electrode and the second auxiliary upper surface electrode with a silver-based conductive paste containing Pd. While the specific resistance of the second auxiliary upper surface electrode can be reduced, it is possible to reduce the occurrence of corrosion such as magnetization on the second auxiliary upper surface electrode due to the presence of Pd. The sex can be further improved.

  According to a third aspect of the present invention, at least the second auxiliary upper surface electrode of the first auxiliary upper surface electrode and the second auxiliary upper surface electrode is formed of a conductive paste made of a base metal excluding silver. Corrosion resistance such as Magration can be improved without incurring an increase in material costs.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a chip resistor 1 according to an embodiment of the present invention.

  The chip resistor 1 has a configuration as described below.

  That is, at least one resistance film 3 and upper surface electrodes 4 for both ends thereof are formed on the upper surface of the chip-shaped insulating substrate 2.

  In order to form the first auxiliary upper surface electrode 5 so as to overlap the upper surfaces of the upper surface electrodes 4, the lateral width dimension W1 of the first auxiliary upper surface electrode 5 is made larger than the lateral width dimension W0 of the upper surface electrode 4. The entire upper surface electrode 4 is configured to be covered.

  On the other hand, in order to form a cover coat 6 covering the upper surface of the resistance film 3 so as to cover it, the first auxiliary upper surface electrode 5 is covered on both ends of the cover coat 6 and both left and right end faces 2a of the insulating substrate 2 are covered. The extension portion 6 extending to is integrally formed.

  In this case, the width dimension W2 of the two extension portions 6a of the cover coat 6 is set to be intermediate between the width dimension W0 of the upper surface electrode 4 and the width dimension W1 of the first auxiliary upper surface electrode 5. An uncovered portion 5a that is not covered with the extension 6a is provided on the left and right outer sides of the upper surface of the first auxiliary upper surface electrode 5.

  An overcoat 7 that covers the cover coat 6 is formed on a portion of the upper surface of the cover coat 6 excluding the two extension portions 6a.

  On the other hand, a second auxiliary upper surface electrode 8 is formed on the upper surface of both extension portions 6a of the cover coat 6 so as to cover the extension portions 6a.

  The second auxiliary upper surface electrode 8 has a lateral width W3 larger than a lateral width W2 of the extension portion 6a of the cover coat 6, so that a part of the left and right sides of the second auxiliary upper surface electrode 8 is not on the left and right outer sides of the extension portion 6a. The covering portion 5 a is joined so as to overlap the first auxiliary upper surface electrode 5, and further, a part of the second auxiliary upper surface electrode 8 is formed to overlap the end portion of the overcoat 7.

  Further, on each of the left and right end faces 2a of the insulating substrate 2, a side electrode 9 is formed such that a part of the side electrode 9 is a part of the upper surface of the second auxiliary upper surface electrode 8 and a lower surface of the insulating substrate 2. It is formed so as to overlap with a part.

  Further, metal plating layers 10 are formed on the surfaces of the second auxiliary upper surface electrodes 8 and the side surface electrodes 9.

  The metal plating layer 10 is constituted by, for example, forming a plating layer of tin or solder on a surface of a nickel plating layer as a base.

  In this configuration, the side electrode 9 and the metal plating layer 10 can be electrically connected to the upper surface electrode 4 via the second auxiliary upper surface electrode 8 and the first auxiliary upper surface electrode 5, while being over electrically connected. The level difference between the upper surface of the coat 7 and the left and right side portions can be reduced or eliminated by the first auxiliary upper surface electrode 5 and the extension 6a of the cover coat 6 and the second auxiliary upper surface electrode 8.

  Since the entire upper surface electrode 4 can be covered with the second auxiliary upper surface electrode 8 and the first auxiliary upper surface electrode 5 and the extension 6a of the cover coat 6 between them, for example, the first electrode 2 Even if peeling or cracking occurs in the portion of the auxiliary upper surface electrode 8 that overlaps the end of the overcoat 7, the fact that the atmospheric air penetrates into the upper surface electrode 4 indicates that the first auxiliary upper surface electrode 5 and The extension 6a of the cover coat 6 can be surely prevented.

  Next, the chip resistor 1 having the above-described configuration is manufactured by the following sequence of steps.

  First, in the first manufacturing process, as shown in FIG. 3, an upper surface electrode 4 having a lateral width W0 is applied to the upper surface of a chip-shaped insulating substrate 2 by screen printing of a silver-based conductive paste, and thereafter A pair of left and right is formed by firing in.

  Next, in the second manufacturing process, as shown in FIGS. 4 and 5, a resistive film 3 is formed on the upper surface of the insulating substrate 2 between the upper surface electrodes 4 by screen printing of the material paste. By application and subsequent baking, both ends of the resistance film 3 are formed to be electrically connected to the upper surface electrodes 4.

  In this case, the resistance film 3 may be formed in the first manufacturing process, and the upper surface electrode 4 may be formed in the second manufacturing process. When forming a pair of left and right bottom electrodes on the bottom surface of the insulating substrate 2, the bottom electrodes are formed by applying the material paste by screen printing and then firing, and then the first manufacturing process. To enter.

  When these steps are completed, only the portion of the resistance film 3 is covered with an undercoat (not shown) made of glass, and then the resistance value in the resistance film 3 is applied to the upper electrode 4 as a probe for energization. Trimming adjustment is performed so that the resistance film 3 has a predetermined resistance value by trimming the resistance film 3 from above the undercoat while measuring the contact film.

  Next, in the third manufacturing process, as shown in FIGS. 6 to 8, the first auxiliary upper surface electrode 5 is applied to the upper surfaces of the upper surface electrodes 4 by screen printing of the material paste, followed by firing. Then, it is formed by overlapping.

  In this case, by making the width dimension W1 of the first auxiliary upper surface electrode 5 larger than the width dimension W0 of the upper surface electrode 4, the upper surface electrode 4 is entirely covered with the first auxiliary upper surface electrode 5. Configure.

  The first auxiliary upper surface electrode 5 is mainly composed of a silver-based conductive paste containing silver as a main component, a silver-based conductive paste containing Pd, or a metal other than silver, for example, a base metal such as nickel. When a silver-based conductive paste or a silver-based conductive paste containing Pd is used, the specific resistance can be lowered, and the silver-based conductive paste or base-metal conductive containing Pd can be reduced. When the conductive paste is used, the first auxiliary upper surface electrode 5 can be prevented from being magnetized, thereby improving the corrosion resistance of the upper surface electrode 4 by the silver-based conductive paste.

  Next, in a fourth manufacturing process, as shown in FIGS. 9 to 11, a cover coat 6 covering the upper surface of the resistance film 3 is applied by screen printing of the glass material paste, and then fired. Then, it is formed by overlapping.

  The cover coat 6 is formed so that both ends of the cover coat 6 are integrally provided with extension portions 6 that cover the first auxiliary upper surface electrode 5 and extend to the left and right end surfaces 2 a of the insulating substrate 2.

  In this case, the width dimension W2 of the two extension portions 6a of the cover coat 6 is set to be intermediate between the width dimension W0 of the upper surface electrode 4 and the width dimension W1 of the first auxiliary upper surface electrode 5. The uncovered portion 5a that is not covered by the extension 6a is provided on the left and right outer sides of the upper surface of the auxiliary upper surface electrode 5.

  Next, in a fifth manufacturing process, as shown in FIGS. 12 and 13, an overcoat 7 that covers the cover coat 6 is applied to a portion of the upper surface of the cover coat 6 excluding the two extension portions 6a. Application of the material paste by screen printing and subsequent baking and sheet formation are performed, or the liquid synthetic resin is applied by application of screen printing and subsequent curing treatment.

  Next, in the sixth manufacturing process, as shown in FIGS. 14 to 16, the second auxiliary upper surface electrode 8 that covers the extended portions 6 a is formed on the upper surfaces of both extended portions 6 a of the cover coat 6. By making the width dimension W3 of the second auxiliary upper surface electrode 8 larger than the width dimension W2 of the extension portion 6a of the cover coat 6, a part of the left and right sides of the second auxiliary upper surface electrode 8 is not on the left and right outer sides of the extension portion 6a. In the covering portion 5 a, the first auxiliary upper surface electrode 5 is overlapped and joined, and a part of the second auxiliary upper surface electrode 8 is formed to overlap the end portion of the overcoat 7.

  The second auxiliary upper surface electrode 8 is mainly composed of a silver-based conductive paste containing silver as a main component, a silver-based conductive paste containing Pd, or a metal other than silver, for example, a base metal such as nickel. When a silver-based conductive paste or a silver-based conductive paste containing Pd is used, the specific resistance can be lowered, and the silver-based conductive paste or base-metal conductive containing Pd can be reduced. When the conductive paste is used, the second auxiliary upper surface electrode 8 can be prevented from being magnetized, thereby improving the corrosion resistance of the upper surface electrode 4 by the silver based conductive paste.

  Next, in the seventh manufacturing process, as shown in FIG. 17, the side electrode 9 is provided on each of the left and right end faces 2 a of the insulating substrate 2, and a part of the side electrode 9 is provided on the second auxiliary top electrode 8. It is formed so as to overlap a part of the upper surface and a part of the lower surface of the insulating substrate 2 (or a part of the lower electrode when the lower electrode is formed on the lower surface).

  Next, in the eighth manufacturing process, barrel plating treatment is performed on the whole so that, for example, a nickel plating layer and a tin plating layer are formed on the surfaces of the second auxiliary upper surface electrode 8 and the both side surface electrodes 9. A metal plating layer 10 made of or a metal plating layer 10 made of a nickel plating layer and a solder plating layer is formed to complete the chip resistor 1 having the structure shown in FIGS.

  A lower electrode is formed on the lower surface of the insulating substrate 2, and a part of the side electrode overlaps the lower electrode, and the metal plating layer 10 is formed on the lower electrode. Of course, it may be.

It is a vertical front view which shows the chip resistor by embodiment of this invention. FIG. 2 is a sectional view taken along line II-II in FIG. 1. It is a perspective view which shows a 1st manufacturing process. It is a perspective view which shows a 2nd manufacturing process. FIG. 5 is an enlarged sectional view taken along line VV in FIG. 4. It is a perspective view which shows a 3rd manufacturing process. FIG. 7 is an enlarged sectional view taken along the line VII-VII in FIG. 6. It is VIII-VIII sectional view taken on the line of FIG. It is a perspective view which shows a 4th manufacturing process. FIG. 10 is an enlarged sectional view taken along line XX in FIG. 9. It is XI-XI sectional view taken on the line of FIG. It is a perspective view which shows a 5th manufacturing process. FIG. 13 is an enlarged sectional view taken along line XIII-XIII in FIG. 12. It is a perspective view which shows a 6th manufacturing process. FIG. 15 is an XV-XV enlarged sectional view of FIG. 14. FIG. 16 is a sectional view taken along line XVI-XVI in FIG. 15. It is a vertical front view which shows a 7th manufacturing process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chip resistor 2 Insulating substrate 2a, 2b End surface of insulating substrate 3 Resistive film 4 Upper surface electrode 5 1st auxiliary | assistant upper surface electrode 5a Uncovered part 6 Cover coat 6a Extension part of cover coat 7 Overcoat 8 2nd auxiliary | assistant upper surface electrode 9 Side surface Electrode 10 Metal plating layer

Claims (4)

In a chip resistor in which at least one resistive film and upper surface electrodes for both ends thereof are formed on the upper surface of a chip-shaped insulating substrate,
A first auxiliary upper surface electrode is formed on the upper surfaces of the upper surface electrodes so as to cover the entire upper surface electrode, and a cover coat covering the upper surface of the resistance film is formed on both ends of the cover coat. An extension portion is formed integrally so as to cover only the portion overlapping the upper surface electrode without covering the left and right outer sides of the upper surface of the first auxiliary upper surface electrode, and the upper surface of the cover coat An overcoat that covers the cover coat is formed on a portion excluding the two extension portions, and a second auxiliary upper surface electrode that covers the extension portion is formed on the upper surface of the two extension portions of the cover coat. A part of the upper surface electrode overlaps and is joined to the first auxiliary upper surface electrode on the left and right outer sides of the extension, and a part of the second auxiliary upper surface electrode overlaps the end of the overcoat. Furthermore, side electrodes are formed on both left and right end surfaces of the insulating substrate so that a part of the side electrodes overlaps a part of the upper surface of the second auxiliary upper surface electrode, and the second auxiliary upper surface electrode is formed. And a chip resistor, wherein a metal plating layer is formed on a surface of the side electrode.   2. The chip resistor according to claim 1, wherein at least a second auxiliary upper surface electrode of the first auxiliary upper surface electrode and the second auxiliary upper surface electrode is formed of a silver-based conductive paste containing Pd. vessel.   2. The chip resistor according to claim 1, wherein at least a second auxiliary upper surface electrode of the first auxiliary upper surface electrode and the second auxiliary upper surface electrode is formed of a conductive paste made of a base metal excluding silver. vessel. Forming at least one resistive film and upper surface electrodes on both ends thereof on the upper surface of the chip-shaped insulating substrate;
Forming a first auxiliary upper surface electrode on the upper surfaces of the upper surface electrodes so as to cover the entire upper surface electrode; and a cover coat for covering the upper surface of the resistance film. A step of integrally forming at both ends an extension that covers only the portion overlapping the upper surface electrode without covering the left and right outer sides of the upper surface of the first auxiliary upper surface electrode;
Forming an overcoat covering the cover coat on a portion of the upper surface of the cover coat excluding the two extension portions;
A second auxiliary upper surface electrode covering the extension portion is bonded to the upper surfaces of both extension portions of the cover coat, and a part of the second auxiliary upper surface electrode is overlapped and joined to the first auxiliary upper surface electrode on the left and right sides of the extension portion. And forming a part of the second auxiliary upper surface electrode so as to overlap an end of the overcoat;
Forming side electrodes on left and right end surfaces of the insulating substrate such that a part of the side electrodes overlaps a part of the upper surface of the second auxiliary upper surface electrode;
Forming a metal plating layer on the surfaces of the second auxiliary upper surface electrode and the side electrode;
A method of manufacturing a chip resistor, comprising:

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