CHIP RESISTOR AND METHOD OF MANUFACTURING THE SAME

A chip resistor includes a resistive element, a first conductive underlying layer, a second conductive underlying layer, a first electrode, and a second electrode. The first electrode includes a first electrode layer. The second electrode includes a second electrode layer. A first electrical resistivity of the first conductive underlying layer is higher than a second electrical resistivity of the first electrode layer and higher than a third electrical resistivity of the resistive element. A fourth electrical resistivity of the second conductive underlying layer is higher than a fifth electrical resistivity of the second electrode layer and higher than the third electrical resistivity of the resistive element.

TECHNICAL FIELD

The present disclosure relates to a chip resistor and a method of manufacturing the same.

BACKGROUND ART

Japanese Patent Laying-Open No. 2018-4267 (PTL 1) discloses a shunt resistor including a resistive element, a first electrode, and a second electrode. The first electrode covers one end of the resistive element. The second electrode covers the other end of the resistive element opposite to the one end of the resistive element. The first electrode and the second electrode are distant from each other.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

A resistance value of the shunt resistor described in PTL 1 is determined by an electrical resistivity of the resistive element, a cross-sectional area of the resistive element, and an interval between the first electrode and the second electrode. When an area of the first electrode and the second electrode is increased to improve heat radiation performance of the shunt resistor described in PTL 1, the interval between the first electrode and the second electrode decreases and the resistance value of the shunt resistor is varied from a designed resistance value. The present disclosure was made in view of the problem above, and an object thereof is to provide a chip resistor that achieves improved heat radiation performance independently of a resistance value.

Solution to Problem

A chip resistor in the present disclosure includes a resistive element, a first conductive underlying layer, a second conductive underlying layer, a first electrode, and a second electrode. The resistive element includes a first main surface, a second main surface opposite to the first main surface, a first side surface connected to the first main surface and the second main surface, and a second side surface opposite to the first side surface. The second side surface is connected to the first main surface and the second main surface. The first conductive underlying layer is provided on the first main surface of the resistive element. The second conductive underlying layer is provided on the first main surface of the resistive element and distant from the first conductive underlying layer. The first electrode is provided on a first side surface side of the resistive element and distant from the second conductive underlying layer. The second electrode is provided on a second side surface side of the resistive element and distant from the first conductive underlying layer and the first electrode. The first electrode includes a first electrode layer provided on the first main surface of the resistive element and the first conductive underlying layer. The second electrode includes a second electrode layer provided on the first main surface of the resistive element and the second conductive underlying layer. A first electrical resistivity of the first conductive underlying layer is higher than a second electrical resistivity of the first electrode layer and higher than a third electrical resistivity of the resistive element. A fourth electrical resistivity of the second conductive underlying layer is higher than a fifth electrical resistivity of the second electrode layer and higher than the third electrical resistivity of the resistive element.

A method of manufacturing a chip resistor in the present disclosure includes forming on a first main surface of a band-shaped resistive element, a first conductive underlying layer and a second conductive underlying layer distant from the first conductive underlying layer, forming a first conductive film on the first conductive underlying layer, the second conductive underlying layer, and a portion of the first main surface exposed from the first conductive underlying layer and the second conductive underlying layer, and dividing the band-shaped resistive element to form a resistive element including a first side surface and a second side surface. As a result of division of the band-shaped resistive element, the first conductive film is divided into a first electrode layer proximate to the first side surface and a second electrode layer proximate to the second side surface and distant from the first electrode layer. A first electrical resistivity of the first conductive underlying layer is higher than a second electrical resistivity of the first electrode layer and higher than a third electrical resistivity of the resistive element. A fourth electrical resistivity of the second conductive underlying layer is higher than a fifth electrical resistivity of the second electrode layer and higher than the third electrical resistivity of the resistive element.

Advantageous Effects of Invention

According to the chip resistor in the present disclosure, heat radiation performance of a chip resistor can be improved independently of a resistance value thereof. According to the method of manufacturing a chip resistor in the present disclosure, a chip resistor that achieves improved heat radiation performance independently of a resistance value thereof can be obtained.

DESCRIPTION OF EMBODIMENTS

An embodiment will be described below. Identical features have identical reference characters allotted and description thereof will not be repeated.

First Embodiment

A chip resistor in a first embodiment will be described with reference toFIGS.1and2. Chip resistor1is, for example, a chip resistor suitable for detection of a current. Chip resistor1is, for example, a shunt resistor. Chip resistor1includes a resistive element10, a first conductive underlying layer17, a second conductive underlying layer18, a first electrode20, and a second electrode25. Chip resistor1may further include a first insulating layer15, a second insulating layer16, and an insulating coating film30.

Resistive element10is formed, for example, of an electrically resistive material such as a Cu—Mn alloy, a Cu—Ni alloy, or an Ni—Cr alloy. Resistive element10includes a first main surface11, a second main surface12opposite to first main surface11, a first side surface13a, a second side surface13bopposite to first side surface13a, a third side surface14a, and a fourth side surface14bopposite to third side surface14a. First main surface11and second main surface12each extend in a first direction (an x direction) and a second direction (a y direction) perpendicular to the first direction (the x direction). For example, a longitudinal direction of resistive element10is defined as the first direction (the x direction). For example, a direction of a short side of resistive element10is defined as the second direction (the y direction). First main surface11and second main surface12are distant from each other in a third direction (a z direction) perpendicular to the first direction (the x direction) and the second direction (the y direction). A direction of thickness of resistive element10is defined as the third direction (the z direction). In mount of chip resistor1on a circuit board50(seeFIG.3), first main surface11of resistive element10faces circuit board50.

First side surface13ais connected to first main surface11and second main surface12. Second side surface13bis connected to first main surface11and second main surface12. First side surface13aand second side surface13bare distant from each other in the first direction (the x direction). Third side surface14ais connected to first main surface11and second main surface12and connected to first side surface13aand second side surface13b. Fourth side surface14bis connected to first main surface11and second main surface12and connected to first side surface13aand second side surface13b. Third side surface14aand fourth side surface14bare distant from each other in the second direction (the y direction). Resistive element10includes a central portion10mexposed from first electrode20and second electrode25in a plan view of first main surface11. Central portion10mis arranged between first electrode20and second electrode25in the first direction (the x direction).

First insulating layer15is provided on first main surface11of resistive element10. First insulating layer15is arranged between first electrode20and second electrode25and spaces first electrode20and second electrode25away from each other. First insulating layer15is arranged between a first electrode layer21and a second electrode layer26and spaces first electrode layer21and second electrode layer26away from each other. First insulating layer15is arranged between first conductive underlying layer17and second conductive underlying layer18and spaces first conductive underlying layer17and second conductive underlying layer18away from each other. First insulating layer15is formed on central portion10mof resistive element10. First insulating layer15protects resistive element10. First insulating layer15includes a first end15aproximate to first side surface13aof resistive element10and a second end15bproximate to second side surface13bof resistive element10. First insulating layer15is formed of an insulating resin such as an epoxy resin.

Second insulating layer16is provided on second main surface12of resistive element10. Second insulating layer16is arranged between first electrode20and second electrode25and spaces first electrode20and second electrode25away from each other. Second insulating layer16is arranged between a third electrode layer22and a fourth electrode layer27and spaces third electrode layer22and fourth electrode layer27away from each other. Second insulating layer16is formed on central portion10mof resistive element10. Second insulating layer16protects resistive element10. Second insulating layer16includes a third end16aproximate to second side surface13bof resistive element10and a fourth end16bproximate to first side surface13aof resistive element10. Third end16aof second insulating layer16may be in contact with fourth electrode layer27. Fourth end16bof second insulating layer16may be in contact with third electrode layer22. Second insulating layer16is formed of an insulating resin such as an epoxy resin.

Insulating coating film30covers third side surface14aof resistive element10, fourth side surface14bof resistive element10, a first band-shaped region in first main surface11of resistive element10that is proximate to third side surface14a, a second band-shaped region in first main surface11of resistive element10that is proximate to fourth side surface14b, a third band-shaped region in second main surface12of resistive element10that is proximate to third side surface14a, and a fourth band-shaped region in second main surface12of resistive element10that is proximate to fourth side surface14b. Longitudinal directions of the first band-shaped region, the second band-shaped region, the third band-shaped region, and the fourth band-shaped region are defined as the first direction (the x direction). Insulating coating film30protects resistive element10. Insulating coating film30is formed of an insulating resin such as an epoxy resin.

First conductive underlying layer17is provided on first main surface11of resistive element10. First conductive underlying layer17is formed on a region in first main surface11of resistive element10, that is proximate to first side surface13aof resistive element10with respect to central portion10mof resistive element10. First conductive underlying layer17includes an end17aproximate to first side surface13aof resistive element10and an end17bproximate to central portion10mof resistive element10. First conductive underlying layer17is provided also on first insulating layer15. First end15aof first insulating layer15is covered with first conductive underlying layer17. End17bof first conductive underlying layer17is exposed from first insulating layer15. Ends17aand17bof first conductive underlying layer17are covered with first electrode layer21. First conductive underlying layer17is formed, for example, of a conductive resin containing a binder resin (for example, an epoxy resin, a phenol resin, or a polyimide resin) and conductive particles (for example, silver particles) dispersed in the binder resin.

A first electrical resistivity of first conductive underlying layer17is higher than a second electrical resistivity of first electrode layer21and higher than a third electrical resistivity of resistive element10. Therefore, while a current flows through chip resistor1, substantially no current flows through first conductive underlying layer17. First conductive underlying layer17does not substantially vary a resistance value of chip resistor1.

The first electrical resistivity of first conductive underlying layer17is, for example, at least ten times as high as the second electrical resistivity of first electrode layer21. The first electrical resistivity of first conductive underlying layer17may be at least twenty times, at least fifty times, or at least one hundred times as high as the second electrical resistivity of first electrode layer21. The first electrical resistivity of first conductive underlying layer17is, for example, at least five times as high as the third electrical resistivity of resistive element10. The first electrical resistivity of first conductive underlying layer17may be at least ten times, at least twenty-five times, or at least fifty times as high as the third electrical resistivity of resistive element10.

Second conductive underlying layer18is provided on first main surface11of resistive element10. Second conductive underlying layer18is formed on a region in first main surface11of resistive element10, that is proximate to second side surface13bof resistive element10with respect to central portion10mof resistive element10. Second conductive underlying layer18includes an end18aproximate to second side surface13bof resistive element10and an end18bproximate to central portion10mof resistive element10. Second conductive underlying layer18is provided also on first insulating layer15. Second end15bof first insulating layer15is covered with second conductive underlying layer18. End18bof second conductive underlying layer18is exposed from first insulating layer15. Ends18aand18bof second conductive underlying layer18are covered with second electrode layer26. Second conductive underlying layer18is distant from first conductive underlying layer17in the first direction (the x direction). Second conductive underlying layer18is formed, for example, of a conductive resin containing a binder resin (for example, an epoxy resin, a phenol resin, or a polyimide resin) and conductive particles (for example, silver particles) dispersed in the binder resin.

A fourth electrical resistivity of second conductive underlying layer18is higher than a fifth electrical resistivity of second electrode layer26and higher than the third electrical resistivity of resistive element10. Therefore, while a current flows through chip resistor1, substantially no current flows through second conductive underlying layer18. Second conductive underlying layer18does not substantially vary a resistance value of chip resistor1.

The fourth electrical resistivity of second conductive underlying layer18is, for example, at least ten times as high as the fifth electrical resistivity of second electrode layer26. The fourth electrical resistivity of second conductive underlying layer18may be at least twenty times, at least fifty times, or at least one hundred times as high as the fifth electrical resistivity of second electrode layer26. The fourth electrical resistivity of second conductive underlying layer18is, for example, at least five times as high as the third electrical resistivity of resistive element10. The fourth electrical resistivity of second conductive underlying layer18may be at least ten times, at least twenty-five times, or at least fifty times as high as the third electrical resistivity of resistive element10.

First electrode20is provided on a first side surface13aside of resistive element10. First electrode20is proximate to first side surface13aof resistive element10with respect to central portion10mof resistive element10in the first direction (the x direction). First electrode20extends along first side surface13aof resistive element10. First electrode20is distant from second conductive underlying layer18and second electrode25in the first direction (the x direction). First electrode20includes first electrode layer21, third electrode layer22, and a first thin metal layer23.

First electrode layer21is provided on first main surface11of resistive element10and first conductive underlying layer17. First electrode layer21is proximate to first side surface13aof resistive element10and extends along first side surface13aof resistive element10. In the plan view of first main surface11or second main surface12, a first portion21mof first electrode layer21that is in contact with resistive element10and most proximate to central portion10mof resistive element10is more proximate to central portion10mof resistive element10than a third portion22mof third electrode layer22that is in contact with resistive element10and most proximate to central portion10mof resistive element10or flush with third portion22mof third electrode layer22.

A thickness of first electrode layer21on first conductive underlying layer17is much smaller than the thickness of first electrode layer21on first main surface11of resistive element10. The thickness of first electrode layer21on first conductive underlying layer17is, for example, at most 0.1 time as large as the thickness of first electrode layer21on first main surface11of resistive element10. The second electrical resistivity of first electrode layer21is lower than the third electrical resistivity of resistive element10. First electrode layer21is formed, for example, of a metal such as copper. First electrode layer21is, for example, a plated layer.

Third electrode layer22is provided on second main surface12of resistive element10. A ninth electrical resistivity of third electrode layer22is lower than the third electrical resistivity of resistive element10. Third electrode layer22is formed, for example, of a metal such as copper. Third electrode layer22is, for example, a plated layer.

First thin metal layer23electrically connects first electrode layer21and third electrode layer22to each other. First thin metal layer23covers first electrode layer21, third electrode layer22, and first side surface13aof resistive element10. First thin metal layer23is formed of a conductive material containing tin such as a solder layer. First thin metal layer23is, for example, a plated layer.

Second electrode25is provided on a second side surface13bside of resistive element10. Second electrode25is proximate to second side surface13bof resistive element10with respect to central portion10mof resistive element10in the first direction (the x direction). Second electrode25extends along second side surface13bof resistive element10. Second electrode25is distant from first conductive underlying layer17and first electrode20in the first direction (the x direction). Second electrode25includes second electrode layer26, fourth electrode layer27, and a second thin metal layer28.

Second electrode layer26is provided on first main surface11of resistive element10and second conductive underlying layer18. Second electrode layer26is proximate to second side surface13bof resistive element10and extends along second side surface13bof resistive element10. In the plan view of first main surface11or second main surface12, a second portion26mof second electrode layer26that is in contact with resistive element10and most proximate to central portion10mof resistive element10is more proximate to central portion10mof resistive element10than a fourth portion27mof fourth electrode layer27that is in contact with resistive element10and most proximate to central portion10mof resistive element10or flush with fourth portion27mof fourth electrode layer27.

A thickness of second electrode layer26on second conductive underlying layer18is much smaller than the thickness of second electrode layer26on first main surface11of resistive element10. The thickness of second electrode layer26on second conductive underlying layer18is, for example, at most 0.1 time as large as the thickness of second electrode layer26on first main surface11of resistive element10. The fifth electrical resistivity of second electrode layer26is lower than the third electrical resistivity of resistive element10. Second electrode layer26is formed, for example, of a metal such as copper. Second electrode layer26is, for example, a plated layer.

Fourth electrode layer27is provided on second main surface12of resistive element10. Fourth electrode layer27is distant from third electrode layer22in the first direction (the x direction). A seventh electrical resistivity of fourth electrode layer27is lower than the third electrical resistivity of resistive element10. Fourth electrode layer27is formed, for example, of a metal such as copper. Fourth electrode layer27is, for example, a plated layer.

Second thin metal layer28electrically connects second electrode layer26and fourth electrode layer27to each other. Second thin metal layer28covers second electrode layer26, fourth electrode layer27, and second side surface13bof resistive element10. Second thin metal layer28is formed of a conductive material containing tin such as a solder layer. Second thin metal layer28is, for example, a plated layer.

First portion21mof first electrode layer21that is in contact with resistive element10and most proximate to central portion10mof resistive element10is more proximate to central portion10mof resistive element10than third portion22mof third electrode layer22that is in contact with resistive element10and most proximate to central portion10mof resistive element10or flush with third portion22mof third electrode layer22. Second portion26mof second electrode layer26that is in contact with resistive element10and most proximate to central portion10mof resistive element10is more proximate to central portion10mof resistive element10than fourth portion27mof fourth electrode layer27that is in contact with resistive element10and most proximate to central portion10mof resistive element10or flush with fourth portion27mof fourth electrode layer27. Therefore, the resistance value of chip resistor1is dependent on a distance L (seeFIG.2) between first portion21mof first electrode layer21and second portion26mof second electrode layer26.

In contrast, as described already, first conductive underlying layer17and second conductive underlying layer18do not substantially vary the resistance value of chip resistor1. In other words, even when a size of first conductive underlying layer17and a size of second conductive underlying layer18vary, the resistance value of chip resistor1does not substantially vary unless distance L varies.

Therefore, though the resistance value of chip resistor1is dependent on distance L, it is not dependent on the size of first electrode20(first electrode layer21) or second electrode25(second electrode layer26). Heat radiation performance of chip resistor1can be improved independently of the resistance value of chip resistor1.

Referring toFIG.3, chip resistor1is mounted, for example, on circuit board50. Specifically, circuit board50includes an insulating substrate51and conductive wires52and53. First electrode20of chip resistor1is bonded to conductive wire52of circuit board50with the use of a bonding member54such as solder. Second electrode25of chip resistor1is bonded to conductive wire53of circuit board50with the use of a bonding member55such as solder.

An exemplary method of manufacturing chip resistor1in the present embodiment will be described with reference toFIGS.1to13.

Referring toFIG.4, the method of manufacturing chip resistor1in the present embodiment includes preparing a resistive element frame5. Resistive element frame5is formed, for example, of an electrically resistive material such as a Cu—Mn alloy, a Cu—Ni alloy, or an Ni—Cr alloy. Resistive element frame5includes a plurality of band-shaped resistive elements10a. The longitudinal direction of band-shaped resistive element10ais defined as the first direction (the x direction). The plurality of band-shaped resistive elements10aeach include first main surface11, second main surface12opposite to first main surface11, third side surface14a, and fourth side surface14bopposite to third side surface14a.

Referring toFIGS.5and6, the method of manufacturing chip resistor1in the present embodiment includes forming first insulating layer15on first main surface11of band-shaped resistive element10aand forming second insulating layer16on second main surface12of band-shaped resistive element10a. First insulating layer15includes first end15awhich is an end of first insulating layer15in the first direction (the x direction) and second end15bwhich is an end of first insulating layer15in the first direction (the x direction) and opposite to first end15a. Second insulating layer16includes third end16awhich is an end of second insulating layer16in the first direction (the x direction) and fourth end16bwhich is an end of second insulating layer16in the first direction (the x direction) and opposite to third end16a.

First insulating layer15and second insulating layer16are formed, for example, of an insulating resin such as an epoxy resin. First insulating layer15and second insulating layer16are provided, for example, by printing such as screen printing.

Referring toFIG.7, the method of manufacturing chip resistor1in the present embodiment includes forming first conductive underlying layer17and second conductive underlying layer18on first main surface11of band-shaped resistive element10a. First conductive underlying layer17and second conductive underlying layer18may further be formed on first insulating layer15. First conductive underlying layer17may cover first end15aof first insulating layer15. Second conductive underlying layer18may cover second end15bof first insulating layer15. First conductive underlying layer17and second conductive underlying layer18are distant from each other in the first direction (the x direction). First conductive underlying layer17and second conductive underlying layer18are formed, for example, of a conductive resin containing a binder resin (for example, an epoxy resin, a phenol resin, or a polyimide resin) and conductive particles (for example, silver particles) dispersed in the binder resin. First conductive underlying layer17and second conductive underlying layer18are provided, for example, by printing such as screen printing.

Referring toFIGS.8and9, the method of manufacturing chip resistor1in the present embodiment includes forming insulating coating film30. Insulating coating film30covers third side surface14aand fourth side surface14bof band-shaped resistive element10a, a first band-shaped region in first main surface11of band-shaped resistive element10athat is proximate to third side surface14a, a second band-shaped region in first main surface11of band-shaped resistive element10athat is proximate to fourth side surface14b, a third band-shaped region in second main surface12of band-shaped resistive element10athat is proximate to third side surface14a, and a fourth band-shaped region in second main surface12of band-shaped resistive element10athat is proximate to fourth side surface14b. Insulating coating film30is formed, for example, of an insulating resin such as an epoxy resin. Insulating coating film30is provided, for example, by dip coating or printing.

Referring toFIGS.10and11, the method of manufacturing chip resistor1in the present embodiment includes forming a first conductive film40and a second conductive film41. First conductive film40is formed on first conductive underlying layer17, second conductive underlying layer18, and a portion of first main surface11of resistive element10that is exposed from first insulating layer15, insulating coating film30, first conductive underlying layer17, and second conductive underlying layer18. Second conductive film41is formed on a portion of second main surface12of resistive element10that is exposed from second insulating layer16and insulating coating film30. First conductive film40and second conductive film41are formed, for example, of a metal such as copper.

First conductive film40and second conductive film41are provided, for example, by plating. First conductive film40and second conductive film41are each, for example, a metal plated film. Resistive element10, first conductive underlying layer17, and second conductive underlying layer18are conductive, whereas first insulating layer15, second insulating layer16, and insulating coating film30are electrically insulating. Therefore, first conductive film40is selectively formed on first conductive underlying layer17, second conductive underlying layer18, and the portion of first main surface11of resistive element10that is exposed from first insulating layer15, insulating coating film30, first conductive underlying layer17, and second conductive underlying layer18. Second conductive film41is selectively formed on the portion of second main surface12of resistive element10that is exposed from second insulating layer16and insulating coating film30.

The first electrical resistivity of first conductive underlying layer17is lower than the third electrical resistivity of resistive element10. The fourth electrical resistivity of second conductive underlying layer18is lower than the third electrical resistivity of resistive element10. Therefore, when first conductive film40is formed, for example, by plating, the thickness of first conductive film40on first conductive underlying layer17becomes much smaller than the thickness of first conductive film40on first main surface11of resistive element10and the thickness of first conductive film40on second conductive underlying layer18becomes much smaller than the thickness of first conductive film40on first main surface11of resistive element10.

Referring toFIGS.12and13, the method of manufacturing chip resistor1in the present embodiment includes dividing band-shaped resistive element10ato form resistive element10including first side surface13aand second side surface13b. As a result of division of band-shaped resistive element10a, first conductive film40is divided into first electrode layer21proximate to first side surface13aand second electrode layer26proximate to second side surface13b. Second electrode layer26is distant from first electrode layer21in the first direction (the x direction). As a result of division of band-shaped resistive element10a, second conductive film41is divided into third electrode layer22proximate to first side surface13aand fourth electrode layer27proximate to second side surface13b. Fourth electrode layer27is distant from third electrode layer22in the first direction (the x direction).

The method of manufacturing chip resistor1in the present embodiment includes forming first thin metal layer23and second thin metal layer28. First thin metal layer23electrically connects first electrode layer21and third electrode layer22to each other. First thin metal layer23covers first electrode layer21, third electrode layer22, and first side surface13aof resistive element10. Second thin metal layer28electrically connects second electrode layer26and fourth electrode layer27to each other. Second thin metal layer28covers second electrode layer26, fourth electrode layer27, and second side surface13bof resistive element10. First thin metal layer23and second thin metal layer28are formed, for example, of a conductive material containing tin such as a solder layer.

First thin metal layer23and second thin metal layer28are provided, for example, by plating. First thin metal layer23and second thin metal layer28are each, for example, a metal plated film. First electrode layer21, second electrode layer26, resistive element10, third electrode layer22, and fourth electrode layer27are conductive, whereas first insulating layer15, second insulating layer16, and insulating coating film30are electrically insulating. Therefore, first thin metal layer23is selectively formed on first electrode layer21, second electrode layer26, and first side surface13aof resistive element10. Second thin metal layer28is selectively formed on third electrode layer22, fourth electrode layer27, and second side surface13bof resistive element10. Chip resistor1shown inFIGS.1and2is thus obtained.

Effects of chip resistor1and the method of manufacturing the same in the present embodiment will be described.

Chip resistor1in the present embodiment includes resistive element10, first conductive underlying layer17, second conductive underlying layer18, first electrode20, and second electrode25. Resistive element10includes first main surface11, second main surface12opposite to first main surface11, first side surface13aconnected to first main surface11and second main surface12, and second side surface13bopposite to first side surface13a. Second side surface13bis connected to first main surface11and second main surface12. First conductive underlying layer17is provided on first main surface11of resistive element10. Second conductive underlying layer18is provided on first main surface11of resistive element10and distant from first conductive underlying layer17. First electrode20is provided on the first side surface13aside of resistive element10and distant from second conductive underlying layer18. Second electrode25is provided on the second side surface13bside of resistive element10and distant from first conductive underlying layer17and first electrode20. First electrode20includes first electrode layer21provided on first main surface11of resistive element10and first conductive underlying layer17. Second electrode25includes second electrode layer26provided on first main surface11of resistive element10and second conductive underlying layer18. The first electrical resistivity of first conductive underlying layer17is higher than the second electrical resistivity of first electrode layer21and higher than the third electrical resistivity of resistive element10. The fourth electrical resistivity of second conductive underlying layer18is higher than the fifth electrical resistivity of second electrode layer26and higher than the third electrical resistivity of resistive element10.

Therefore, though the resistance value of chip resistor1is dependent on distance L (seeFIG.2), it is not dependent on the size of first electrode20(first electrode layer21) and the size of second electrode25(second electrode layer26). First electrode layer21is provided not only on first main surface11of resistive element10but also on first conductive underlying layer17. Second electrode layer26is provided not only on first main surface11of resistive element10but also on second conductive underlying layer18. When chip resistor1is bonded to circuit board50(seeFIG.3), chip resistor1can be bonded to circuit board50over a wider bonding area. Heat generated in chip resistor1can efficiently be radiated to circuit board50. Chip resistor1in the present embodiment can achieve improved heat radiation performance independently of the resistance value thereof.

As set forth above, though the resistance value of chip resistor1is dependent on distance L (seeFIG.2), it is not dependent on the size of first electrode20(first electrode layer21) and the size of second electrode25(second electrode layer26). Therefore, the size of first electrode20(first electrode layer21) and the size of second electrode layer25(second electrode layer26) can be common among a plurality of chip resistors1various in distance L and resistance value. The size of conductive wire52and the size of conductive wire53of circuit board50(seeFIG.3) on which chip resistor1is mounted can be common. Design of circuit board50on which chip resistor1is mounted can be simplified.

In chip resistor1in the present embodiment, first conductive underlying layer17and second conductive underlying layer18are formed of a conductive resin containing a binder resin and conductive particles (for example, silver particles) dispersed in the binder resin. First electrode layer21and second electrode layer26are formed of a metal. Therefore, heat radiation performance of chip resistor1can be improved independently of the resistance value of chip resistor1. Cost for manufacturing chip resistor1can be reduced.

Chip resistor1in the present embodiment further includes first insulating layer15provided on first main surface11of resistive element10. First insulating layer15is arranged between first electrode20and second electrode25and arranged between first conductive underlying layer17and second conductive underlying layer18.

First insulating layer15protects resistive element10. Chip resistor1has a longer lifetime. First insulating layer15prevents first conductive underlying layer17and second conductive underlying layer18from coming in contact with each other and prevents first electrode layer21and second electrode layer26from coming in contact with each other.

In chip resistor1in the present embodiment, first end15aof first insulating layer15proximate to first side surface13aof resistive element10is covered with first conductive underlying layer17. Second end15bof first insulating layer15proximate to second side surface13bof resistive element10is covered with second conductive underlying layer18. Chip resistor1in the present embodiment can achieve improved heat radiation performance independently of the resistance value thereof.

In chip resistor1in the present embodiment, first electrode20further includes third electrode layer22and first thin metal layer23. Third electrode layer22is provided on second main surface12of resistive element10. First thin metal layer23electrically connects first electrode layer21and third electrode layer22to each other. Second electrode25further includes fourth electrode layer27and second thin metal layer28. Fourth electrode layer27is provided on second main surface12of resistive element10and distant from third electrode layer22. Second thin metal layer28electrically connects second electrode layer26and fourth electrode layer27to each other.

When chip resistor1is mounted on circuit board50(seeFIG.3), heat generated in chip resistor1can be radiated to circuit board50not only from first main surface11of resistive element10but also from second main surface12of resistive element10through third electrode layer22, first thin metal layer23, fourth electrode layer27, and second thin metal layer28. Heat radiation performance of chip resistor1can be improved.

In chip resistor1in the present embodiment, resistive element10includes central portion10mexposed from first electrode20and second electrode25in the plan view of first main surface11. First portion21mof first electrode layer21that is in contact with resistive element10and most proximate to central portion10mof resistive element10is more proximate to central portion10mof resistive element10than third portion22mof third electrode layer22that is in contact with resistive element10and most proximate to central portion10mof resistive element10or flush with third portion22mof third electrode layer22. Second portion26mof second electrode layer26that is in contact with resistive element10and most proximate to central portion10mof resistive element10is more proximate to central portion10mof resistive element10than fourth portion27mof fourth electrode layer27that is in contact with resistive element10and most proximate to central portion10mof resistive element10or flush with fourth portion27mof fourth electrode layer27.

Though the resistance value of chip resistor1is dependent on distance L between first portion21mof first electrode layer21and second portion26mof second electrode layer26, it is not dependent on the size of first electrode20and the size of second electrode25. Chip resistor1in the present embodiment can achieve improved heat radiation performance independently of the resistance value thereof.

In chip resistor1in the present embodiment, first thin metal layer23and second thin metal layer28are each formed of a conductive material containing tin. Therefore, chip resistor1can readily be mounted on circuit board50(seeFIG.3) with the use of solder.

Chip resistor1in the present embodiment further includes second insulating layer16provided on second main surface12of resistive element10. Second insulating layer16is arranged between third electrode layer22and fourth electrode layer27.

Second insulating layer16protects resistive element10. Chip resistor1has a longer lifetime. Second insulating layer16prevents third electrode layer22and fourth electrode layer27from coming in contact with each other.

In chip resistor1in the present embodiment, chip resistor1is a shunt resistor. Therefore, heat radiation performance of chip resistor1can be improved independently of the resistance value thereof. Chip resistor1suitable for detection of a current can be provided.

The method of manufacturing chip resistor1in the present embodiment includes forming on first main surface11of band-shaped resistive element10a, first conductive underlying layer17and second conductive underlying layer18distant from first conductive underlying layer17and forming first conductive film40on first conductive underlying layer17, second conductive underlying layer18, and the portion of first main surface11of band-shaped resistive element10aexposed from first conductive underlying layer17and second conductive underlying layer18. The method of manufacturing chip resistor1in the present embodiment further includes dividing band-shaped resistive element10ato form resistive element10including first side surface13aand second side surface13b. As a result of division of band-shaped resistive element10a, first conductive film40is divided into first electrode layer21proximate to first side surface13aand second electrode layer26proximate to second side surface13band distant from first electrode layer21. The first electrical resistivity of first conductive underlying layer17is higher than the second electrical resistivity of first electrode layer21and higher than the third electrical resistivity of resistive element10. The fourth electrical resistivity of second conductive underlying layer18is higher than the fifth electrical resistivity of second electrode layer26and higher than the third electrical resistivity of resistive element10.

Therefore, though the resistance value of chip resistor1is dependent on distance L (seeFIG.2), it is not dependent on the size of first electrode layer21and the size of second electrode layer26. First electrode layer21is provided not only on first main surface11of resistive element10but also on first conductive underlying layer17. Second electrode layer26is provided not only on first main surface11of resistive element10but also on second conductive underlying layer18. When chip resistor1is bonded to circuit board50(seeFIG.3), chip resistor1can be bonded to circuit board50over a wider bonding area. Heat generated in chip resistor1can efficiently be radiated to circuit board50. According to the method of manufacturing chip resistor1in the present embodiment, chip resistor1that achieves improved heat radiation performance independently of the resistance value thereof can be obtained.

As set forth above, though the resistance value of chip resistor1is dependent on distance L (seeFIG.2), it is not dependent on the size of first electrode layer21and the size of second electrode layer26. Therefore, the size of first electrode layer21and the size of second electrode layer26can be common among a plurality of chip resistors1various in distance L and resistance value. The size of conductive wire52and the size of conductive wire53of circuit board50(seeFIG.3) on which chip resistor1is mounted can be common. Design of circuit board50(seeFIG.3) on which chip resistor1is mounted can be simplified.

In the method of manufacturing chip resistor1in the present embodiment, first conductive underlying layer17and second conductive underlying layer18are provided by printing. First conductive film40is provided by plating. Therefore, productivity of chip resistor1can be improved and cost for manufacturing chip resistor1can be reduced.

Second Embodiment

A chip resistor1bin a second embodiment will be described with reference toFIGS.14and15. Though chip resistor1bin the present embodiment is similar in configuration to chip resistor1in the first embodiment, it is different in aspects below.

Chip resistor1bfurther includes a third conductive underlying layer33. Chip resistor1bmay further include a third insulating layer35.

Third conductive underlying layer33is provided on second main surface12of resistive element10and second insulating layer16. Third conductive underlying layer33is in contact with fourth electrode layer27and distant from third electrode layer22in the first direction (the x direction). A part of third conductive underlying layer33is exposed from third insulating layer35. Third conductive underlying layer33includes an end33aproximate to first side surface13a. End33aof third conductive underlying layer33is covered with third insulating layer35. End33aof third conductive underlying layer33is distant from third electrode layer22in the first direction (the x direction).

Third end16aof second insulating layer16proximate to second side surface13bof resistive element10is covered with third conductive underlying layer33. In the plan view of second main surface12of resistive element10, third conductive underlying layer33overlaps with second conductive underlying layer18. In the plan view of second main surface12of resistive element10, third conductive underlying layer33overlaps with central portion10mof resistive element10in the first direction (the x direction) in which first electrode20and second electrode25are distant from each other. In the plan view of second main surface12of resistive element10, third conductive underlying layer33may overlap with first conductive underlying layer17. Fourth end16bof second insulating layer16proximate to first side surface13aof resistive element10is exposed from third conductive underlying layer33.

A sixth electrical resistivity of third conductive underlying layer33is higher than the seventh electrical resistivity of fourth electrode layer27and higher than the third electrical resistivity of resistive element10. Therefore, when a current flows through chip resistor1, substantially no current flows through third conductive underlying layer33. Third conductive underlying layer33does not substantially vary the resistance value of chip resistor1.

The sixth electrical resistivity of third conductive underlying layer33is, for example, at least ten times as high as the seventh electrical resistivity of fourth electrode layer27. The sixth electrical resistivity of third conductive underlying layer33may be at least twenty times, at least fifty times, or at least one hundred times as high as the seventh electrical resistivity of fourth electrode layer27. The sixth electrical resistivity of third conductive underlying layer33is, for example, at least five times as high as the third electrical resistivity of resistive element10. The sixth electrical resistivity of third conductive underlying layer33may be at least ten times, at least twenty-five times, or at least fifty times as high as the third electrical resistivity of resistive element10. Third conductive underlying layer33is formed of a conductive resin containing a binder resin (for example, an epoxy resin, a phenol resin, or a polyimide resin) and conductive particles (for example, silver particles) dispersed in the binder resin.

Fourth electrode layer27is further provided on third conductive underlying layer33. A thickness of fourth electrode layer27on third conductive underlying layer33is much smaller than the thickness of fourth electrode layer27on first main surface11of resistive element10. The thickness of fourth electrode layer27on third conductive underlying layer33is, for example, at most 0.1 time as large as the thickness of fourth electrode layer27on first main surface11of resistive element10.

Third insulating layer35is provided on third conductive underlying layer33and second insulating layer16. Third insulating layer35protects third conductive underlying layer33. Third insulating layer35is formed of an insulating resin such as an epoxy resin.

A method of manufacturing chip resistor1bin the present embodiment will be described with reference toFIGS.4to7and14to20. Though the method of manufacturing chip resistor1bin the present embodiment includes steps similar to those in the method of manufacturing chip resistor1in the first embodiment, it is different mainly in aspects below.

The method of manufacturing chip resistor1cin the present embodiment includes the steps shown inFIGS.4to6. Referring toFIGS.7and16, the method of manufacturing chip resistor1bin the present embodiment includes forming first conductive underlying layer17and second conductive underlying layer18on first main surface11of band-shaped resistive element10aand forming third conductive underlying layer33on second main surface12of band-shaped resistive element10aand second insulating layer16.

Third end16aof second insulating layer16is covered with third conductive underlying layer33. In the plan view of second main surface12of band-shaped resistive element10a, third conductive underlying layer33overlaps with second conductive underlying layer18. In the plan view of second main surface12of band-shaped resistive element10a, third conductive underlying layer33may overlap with first conductive underlying layer17. Fourth end16bof second insulating layer16is exposed from third conductive underlying layer33.

Third conductive underlying layer33is formed, for example, of a conductive resin containing a binder resin (for example, an epoxy resin, a phenol resin, or a polyimide resin) and conductive particles (for example, silver particles) dispersed in the binder resin. Third conductive underlying layer33is provided, for example, by printing such as screen printing.

Referring toFIG.17, the method of manufacturing chip resistor1bin the present embodiment includes forming third insulating layer35on third conductive underlying layer33and second insulating layer16. A part of third conductive underlying layer33is exposed from third insulating layer35. Third insulating layer35is formed, for example, of an insulating resin such as an epoxy resin. Third insulating layer35is provided, for example, by printing such as screen printing.

Referring toFIGS.8and18, the method of manufacturing chip resistor1bin the present embodiment includes forming insulating coating film30. The step of forming insulating coating film30in the present embodiment is similar to the step of forming insulating coating film30in the first embodiment. Insulating coating film30further covers a fifth band-shaped region of third insulating layer35that is proximate to third side surface14aand a sixth band-shaped region of third insulating layer35that is proximate to fourth side surface14b.

Referring toFIGS.10and19, the method of manufacturing chip resistor1bin the present embodiment includes forming first conductive film40and second conductive film41similarly to the method of manufacturing chip resistor1in the first embodiment. Second conductive film41is formed on third conductive underlying layer33and a portion of second main surface12of resistive element10exposed from insulating coating film30, third insulating layer35, and third conductive underlying layer33.

The sixth electrical resistivity of third conductive underlying layer33is lower than the third electrical resistivity of resistive element10. Therefore, when second conductive film41is formed, for example, by plating, the thickness of second conductive film41on third electrode layer33becomes much smaller than the thickness of second electrode layer41on first main surface11of resistive element10.

Referring toFIGS.12and20, the method of manufacturing chip resistor1bin the present embodiment includes dividing band-shaped resistive element10ato form resistive element10including first side surface13aand second side surface13bsimilarly to the method of manufacturing chip resistor1in the first embodiment. As a result of division of band-shaped resistive element10a, first conductive film40is divided into first electrode layer21and second electrode layer26. Second conductive film41is divided into third electrode layer22and fourth electrode layer27. Third conductive underlying layer33is in contact with fourth electrode layer27and distant from third electrode layer22. Fourth electrode layer27is provided not only on second main surface12of resistive element10but also on third conductive underlying layer33.

The method of manufacturing chip resistor1bin the present embodiment includes forming first thin metal layer23and second thin metal layer28similarly to the method of manufacturing chip resistor1in the first embodiment. Chip resistor1bshown inFIGS.14and15is thus obtained.

Chip resistor1band the method of manufacturing the same in the present embodiment achieve effects below in addition to the effects of chip resistor1and the method of manufacturing the same in the first embodiment.

Chip resistor1bin the present embodiment further includes third conductive underlying layer33provided on second main surface12of resistive element10and second insulating layer16. Third conductive underlying layer33is in contact with fourth electrode layer27and distant from third electrode layer22. Third end16aof second insulating layer16proximate to second side surface13bof resistive element10is covered with third conductive underlying layer33. The sixth electrical resistivity of third conductive underlying layer33is higher than the seventh electrical resistivity of fourth electrode layer27and higher than the third electrical resistivity of resistive element10.

When chip resistor1bis mounted on circuit board50(seeFIG.3), heat generated in chip resistor1bcan be radiated to circuit board50not only from first main surface11of resistive element10but also from second main surface12of resistive element10through third conductive underlying layer33, fourth electrode layer27, and second thin metal layer28. Third conductive underlying layer33does not substantially vary the resistance value of chip resistor1b. Heat radiation performance of chip resistor1bcan be improved independently of the resistance value of chip resistor1b.

In chip resistor1bin the present embodiment, in the plan view of second main surface12of resistive element10, third conductive underlying layer33overlaps with central portion10mof resistive element10in the direction (the first direction (the x direction)) in which first electrode20and second electrode25are distant from each other.

When chip resistor1bis mounted on circuit board50(seeFIG.3), heat generated in chip resistor1bcan be radiated to circuit board50from central portion10mof resistive element10where a temperature is highest in chip resistor1bthrough third conductive underlying layer33, fourth electrode layer27, and second thin metal layer28. Heat radiation performance of chip resistor1bcan be improved.

In chip resistor1bin the present embodiment, third conductive underlying layer33is formed of a conductive resin containing a binder resin and conductive particles dispersed in the binder resin. Fourth electrode layer27is formed of a metal. Therefore, heat radiation performance of chip resistor1bcan be improved independently of the resistance value thereof. Cost for manufacturing chip resistor1bcan be reduced.

The method of manufacturing chip resistor1bin the present embodiment further includes forming second insulating layer16on second main surface12of band-shaped resistive element10aopposite to first main surface11of band-shaped resistive element10a, forming third conductive underlying layer33on second main surface12of band-shaped resistive element10aand second insulating layer16, forming second conductive film41on third conductive underlying layer33and the portion of second main surface12of band-shaped resistive element10athat is exposed from third conductive underlying layer33, and forming first thin metal layer23and second thin metal layer28. As a result of division of band-shaped resistive element10a, second conductive film41is divided into third electrode layer22proximate to first side surface13aand fourth electrode layer27proximate to second side surface13band distant from third electrode layer22. Third conductive underlying layer33is in contact with fourth electrode layer27and distant from third electrode layer22. First thin metal layer23electrically connects first electrode layer21and third electrode layer22to each other. Second thin metal layer28electrically connects second electrode layer26and fourth electrode layer27to each other. The sixth electrical resistivity of third conductive underlying layer33is higher than the seventh electrical resistivity of fourth electrode layer27and higher than the third electrical resistivity of resistive element10.

When chip resistor1bis mounted on circuit board50(seeFIG.3), heat generated in chip resistor1bcan be radiated not only from first main surface11of resistive element10but also from second main surface12of resistive element10through third conductive underlying layer33, fourth electrode layer27, and second thin metal layer28. Third conductive underlying layer33does not substantially vary the resistance value of chip resistor1b. Chip resistor1bthat achieves improved heat radiation performance independently of the resistance value thereof can be obtained.

In the method of manufacturing chip resistor1bin the present embodiment, third conductive underlying layer33is provided by printing. Second conductive film41is provided by plating. Therefore, productivity of chip resistor1bcan be improved and cost for manufacturing chip resistor1bcan be reduced.

Third Embodiment

A chip resistor1cin a third embodiment will be described with reference toFIGS.21and22. Though chip resistor1cin the present embodiment is similar in configuration to chip resistor1bin the second embodiment, it is different in aspects below.

Chip resistor1cfurther includes a fourth conductive underlying layer34. Fourth conductive underlying layer34is provided on second main surface12of resistive element10and second insulating layer16. Fourth conductive underlying layer34is in contact with third electrode layer22and distant from third conductive underlying layer33and fourth electrode layer27in the first direction (the x direction). A part of fourth conductive underlying layer34is exposed from third insulating layer35. Fourth conductive underlying layer34includes an end34aproximate to second side surface13b. End34aof fourth conductive underlying layer34is covered with third insulating layer35. End34aof fourth conductive underlying layer34is distant from end33aof third conductive underlying layer33and fourth electrode layer27in the first direction (the x direction).

Fourth end16bof second insulating layer16proximate to first side surface13aof resistive element10is covered with fourth conductive underlying layer34. In the plan view of second main surface12of resistive element10, fourth conductive underlying layer34overlaps with first conductive underlying layer17. In the plan view of second main surface12of resistive element10, fourth conductive underlying layer34is distant from central portion10mof resistive element10in the first direction (the x direction) in which first electrode20and second electrode25are distant from each other.

An eighth electrical resistivity of fourth conductive underlying layer34is higher than the ninth electrical resistivity of third electrode layer22and higher than the third electrical resistivity of resistive element10. Therefore, when a current flows through chip resistor1, substantially no current flows through fourth conductive underlying layer34. Fourth conductive underlying layer34does not substantially vary the resistance value of chip resistor1.

The eighth electrical resistivity of fourth conductive underlying layer34is, for example, at least ten times as high as the ninth electrical resistivity of third electrode layer22. The eighth electrical resistivity of fourth conductive underlying layer34may be at least twenty times, at least fifty times, or at least one hundred times as high as the ninth electrical resistivity of third electrode layer22. The eighth electrical resistivity of fourth conductive underlying layer34is, for example, at least five times as high as the third electrical resistivity of resistive element10. The eighth electrical resistivity of fourth conductive underlying layer34may be at least ten times, at least twenty-five times, or at least fifty times as high as the third electrical resistivity of resistive element10. Fourth conductive underlying layer34is formed of a conductive resin containing a binder resin (for example, an epoxy resin, a phenol resin, or a polyimide resin) and conductive particles (for example, silver particles) dispersed in the binder resin.

Third electrode layer22is further provided on fourth conductive underlying layer34. A thickness of third electrode layer22on fourth conductive underlying layer34is much smaller than the thickness of third electrode layer22on first main surface11of resistive element10. The thickness of third electrode layer22on fourth conductive underlying layer34is, for example, at most 0.1 time as large as the thickness of third electrode layer22on first main surface11of resistive element10.

Third insulating layer35is provided on third conductive underlying layer33, fourth conductive underlying layer34, and second insulating layer16. Third insulating layer35protects third conductive underlying layer33and fourth conductive underlying layer34.

A method of manufacturing chip resistor1cin the present embodiment will be described with reference toFIGS.4to7,10,12, and21to25. Though the method of manufacturing chip resistor1cin the present embodiment includes steps similar to those in the method of manufacturing chip resistor1bin the second embodiment, it is different mainly in aspects below.

The method of manufacturing chip resistor1cin the present embodiment includes the steps shown inFIGS.4to6. Referring toFIGS.7and23, the method of manufacturing chip resistor1cin the present embodiment includes forming first conductive underlying layer17and second conductive underlying layer18on first main surface11of band-shaped resistive element10aand forming third conductive underlying layer33and fourth conductive underlying layer34on second main surface12of band-shaped resistive element10aand second insulating layer16.

Fourth end16bof second insulating layer16is covered with fourth conductive underlying layer34. In the plan view of second main surface12of band-shaped resistive element10a, fourth conductive underlying layer34overlaps with first conductive underlying layer17. Fourth conductive underlying layer34is distant from third conductive underlying layer33in the first direction (the x direction).

Fourth conductive underlying layer34is formed, for example, of a conductive resin containing a binder resin (for example, an epoxy resin, a phenol resin, or a polyimide resin) and conductive particles (for example, silver particles) dispersed in the binder resin. Fourth conductive underlying layer34is provided, for example, by printing such as screen printing.

Referring toFIG.24, the method of manufacturing chip resistor1cin the present embodiment includes forming third insulating layer35on third conductive underlying layer33, fourth conductive underlying layer34, and second insulating layer16. A part of third conductive underlying layer33and a part of fourth conductive underlying layer34are exposed from third insulating layer35.

Referring toFIGS.8and25, the method of manufacturing chip resistor1cin the present embodiment includes forming insulating coating film30. The step of forming insulating coating film30in the present embodiment is similar to the step of forming insulating coating film30in the second embodiment.

Referring toFIGS.10and19, the method of manufacturing chip resistor1cin the present embodiment includes forming first conductive film40and second conductive film41similarly to the method of manufacturing chip resistor1bin the second embodiment. Second conductive film41is formed on third conductive underlying layer33, fourth conductive underlying layer34, and a portion of second main surface12of resistive element10exposed from insulating coating film30, third insulating layer35, third conductive underlying layer33, and fourth conductive underlying layer34.

The eighth electrical resistivity of fourth conductive underlying layer34is lower than the third electrical resistivity of resistive element10. Therefore, when second conductive film41is formed, for example, by plating, the thickness of second conductive film41on fourth conductive underlying layer34becomes much smaller than the thickness of second conductive film41on first main surface11of resistive element10.

Referring toFIGS.12and20, the method of manufacturing chip resistor1cin the present embodiment includes dividing band-shaped resistive element10ato form resistive element10including first side surface13aand second side surface13bsimilarly to the method of manufacturing chip resistor1bin the second embodiment. As a result of division of band-shaped resistive element10a, first conductive film40is divided into first electrode layer21and second electrode layer26. Second conductive film41is divided into third electrode layer22and fourth electrode layer27. Fourth conductive underlying layer34is in contact with third electrode layer22and distant from fourth electrode layer27. Third electrode layer22is formed not only on second main surface12of resistive element10but also on fourth conductive underlying layer34.

The method of manufacturing chip resistor1cin the present embodiment includes forming first thin metal layer23and second thin metal layer28similarly to the method of manufacturing chip resistor1bin the second embodiment. Chip resistor1cshown inFIGS.21and22is thus obtained.

Chip resistor1cand the method of manufacturing the same in the present embodiment achieve effects below in addition to the effects of chip resistor1band the method of manufacturing the same in the second embodiment.

Chip resistor1cin the present embodiment further includes fourth conductive underlying layer34provided on second main surface12of resistive element10and second insulating layer16. Fourth conductive underlying layer34is in contact with third electrode layer22and distant from third conductive underlying layer33and fourth electrode layer27. Fourth end16bof second insulating layer16proximate to first side surface13aof resistive element10is covered with fourth conductive underlying layer34. The eighth electrical resistivity of fourth conductive underlying layer34is higher than the ninth electrical resistivity of third electrode layer22and higher than the third electrical resistivity of resistive element10.

When chip resistor1cis mounted on circuit board50(seeFIG.3), heat generated in chip resistor1ccan be radiated to circuit board50not only from first main surface11of resistive element10but also from second main surface12of resistive element10through third conductive underlying layer33, fourth conductive underlying layer34, third electrode layer22, and fourth electrode layer27. Fourth conductive underlying layer34does not substantially vary the resistance value of chip resistor1c. Heat radiation performance of chip resistor1ccan be improved independently of the resistance value thereof.

In chip resistor1cin the present embodiment, fourth conductive underlying layer34is formed of a conductive resin containing a binder resin and conductive particles dispersed in the binder resin. Third electrode layer22is formed of a metal. Therefore, heat radiation performance of chip resistor1ccan be improved independently of the resistance value thereof. Cost for manufacturing chip resistor1ccan be reduced.

The method of manufacturing chip resistor1cin the present embodiment further includes forming fourth conductive underlying layer34distant from third conductive underlying layer33, on second main surface12of band-shaped resistive element10aand second insulating layer16. Second conductive film41is formed also on fourth conductive underlying layer34. Fourth conductive underlying layer34is in contact with third electrode layer22and distant from fourth electrode layer27. The eighth electrical resistivity of fourth conductive underlying layer34is higher than the ninth electrical resistivity of third electrode layer22and higher than the third electrical resistivity of resistive element10.

When chip resistor1cis mounted on circuit board50(seeFIG.3), heat generated in chip resistor1ccan be radiated to circuit board50not only from first main surface11of resistive element10but also from second main surface12of resistive element10through third conductive underlying layer33, fourth conductive underlying layer34, third electrode layer22, and fourth conductive underlying layer34. Fourth conductive underlying layer34does not substantially vary the resistance value of chip resistor1c. Chip resistor1cthat achieves improved heat radiation performance independently of the resistance value thereof can be obtained.

In the method of manufacturing chip resistor1cin the present embodiment, fourth conductive underlying layer34is provided by printing. Therefore, productivity of chip resistor1ccan be improved and cost for manufacturing chip resistor1ccan be reduced.

Fourth Embodiment

A chip resistor1din a fourth embodiment will be described with reference toFIGS.26and27. Though chip resistor1din the present embodiment is similar in configuration to chip resistor1in the first embodiment, it is different in aspects below.

First insulating layer15is provided also on first conductive underlying layer17. First end15aof first insulating layer15is exposed from first conductive underlying layer17. End17bof first conductive underlying layer17is covered with first insulating layer15. End17bof first conductive underlying layer17is distant from first electrode layer21. First insulating layer15is provided also on second conductive underlying layer18. Second end15bof first insulating layer15is exposed from first conductive underlying layer17. End18bof second conductive underlying layer18is covered with first insulating layer15. End18bof second conductive underlying layer18is distant from second electrode layer26.

A method of manufacturing chip resistor1din the present embodiment will be described with reference toFIGS.4,6,9,11,13, and28to32. Though the method of manufacturing chip resistor1din the present embodiment includes steps similar to those in the method of manufacturing chip resistor1in the first embodiment, it is different mainly in aspects below.

The method of manufacturing chip resistor1din the present embodiment includes the step shown inFIG.4. Referring toFIG.28, the method of manufacturing chip resistor1din the present embodiment includes forming first conductive underlying layer17and second conductive underlying layer18on first main surface11of band-shaped resistive element10a. First conductive underlying layer17and second conductive underlying layer18are distant from each other in the first direction (the x direction).

First conductive underlying layer17includes end17awhich is an end of first conductive underlying layer17in the first direction (the x direction) and end17bwhich is an end of first conductive underlying layer17in the first direction (the x direction) and opposite to end17a. Second conductive underlying layer18includes end18awhich is an end of second conductive underlying layer18in the first direction (the x direction) and end18bwhich is an end of second conductive underlying layer18in the first direction (the x direction) and opposite to end18a. End17bof first conductive underlying layer17is opposed to end18bof second conductive underlying layer18. First conductive underlying layer17and second conductive underlying layer18are provided, for example, by printing such as screen printing.

Referring toFIGS.6and29, the method of manufacturing chip resistor1din the present embodiment includes forming first insulating layer15on first main surface11of band-shaped resistive element10a, first conductive underlying layer17, and second conductive underlying layer18and forming second insulating layer16on second main surface12of band-shaped resistive element10a. First insulating layer15is formed between first conductive underlying layer17and second conductive underlying layer18. End17bof first conductive underlying layer17is covered with first insulating layer15. End18bof second conductive underlying layer18is covered with first insulating layer15.

First insulating layer15includes first end15awhich is an end of first insulating layer15in the first direction (the x direction) and second end15bwhich is an end of first insulating layer15in the first direction (the x direction) and opposite to first end15a. First end15aof first insulating layer15is located on first conductive underlying layer17and covers end17bof first conductive underlying layer17. Second end15bof first insulating layer15is located on second conductive underlying layer18and covers end18bof second conductive underlying layer18. Second insulating layer16includes third end16awhich is an end of second insulating layer16in the first direction (the x direction) and fourth end16bwhich is an end of second insulating layer16in the first direction (the x direction) and opposite to third end16a.

Referring toFIGS.9and30, the method of manufacturing chip resistor1din the present embodiment includes forming insulating coating film30similarly to the method of manufacturing chip resistor1in the first embodiment. Referring toFIGS.11and31, the method of manufacturing chip resistor1din the present embodiment includes forming first conductive film40and second conductive film41similarly to the method of manufacturing chip resistor1in the first embodiment. Referring toFIGS.13and32, the method of manufacturing chip resistor1din the present embodiment includes dividing band-shaped resistive element10ato form resistive element10including first side surface13aand second side surface13bsimilarly to the method of manufacturing chip resistor1in the first embodiment. The method of manufacturing chip resistor1din the present embodiment includes forming first thin metal layer23and second thin metal layer28similarly to the method of manufacturing chip resistor1in the first embodiment. Chip resistor1dshown inFIGS.26and27is thus obtained.

Chip resistor1din the present embodiment achieves effects below similar to those of chip resistor1in the first embodiment.

In chip resistor1din the present embodiment, resistive element10includes central portion10mexposed from first electrode20and second electrode25in the plan view of first main surface11. End17bof first conductive underlying layer17proximate to central portion10mof resistive element10is covered with first insulating layer15. End18bof second conductive underlying layer18proximate to central portion10mof resistive element10is covered with first insulating layer15. Chip resistor1din the present embodiment can achieve improved heat radiation performance independently of the resistance value thereof.

It should be understood that the first to fourth embodiments disclosed herein are illustrative and non-restrictive in every respect. At least two of the first to fourth embodiments disclosed herein may be combined unless there is inconsistency. For example, third conductive underlying layer33and third insulating layer35in the second embodiment may be provided in chip resistor1din the fourth embodiment.

Third conductive underlying layer33, fourth conductive underlying layer34, and third insulating layer35in the third embodiment may be provided in chip resistor1din the fourth embodiment. The scope of the present disclosure is defined by the terms of the claims rather than the description above and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

REFERENCE SIGNS LIST