JP6688025B2 - Chip resistor and method of manufacturing chip resistor - Google Patents

Description

  The present invention relates to a chip resistor surface-mounted on a circuit board by soldering, and a method for manufacturing such a chip resistor.

  This type of chip resistor is composed of a rectangular parallelepiped insulating substrate made of ceramics, a pair of front electrodes facing each other at a predetermined interval on the surface of the insulating substrate, and insulating so as to be connected to the pair of surface electrodes. A resistor provided on the front surface of the substrate, a protective film made of resin provided so as to cover the resistor, a pair of back electrodes arranged to face the back surface of the insulating substrate with a predetermined gap, and a front electrode. And a pair of end face electrodes provided on both end faces of the insulating substrate so as to conduct the back electrode, and a pair of outer electrodes formed by plating the outer surfaces of these end face electrodes.

  The chip resistor configured in this way prints the solder paste on the land provided on the circuit board, mounts the external electrode on the land with the back electrode facing downward, and melts the solder paste in this state. By solidifying, it is surface-mounted on the circuit board.

  On the other hand, as disclosed in Patent Document 1, in a chip-shaped electronic component such as a chip capacitor, a technique is known in which cap-shaped end face electrodes are formed at both longitudinal ends of a prismatic chip element body. . In such a chip-shaped electronic component, since the cap-shaped end surface electrodes extend to the upper surface and lower surface and both side surfaces of the prismatic chip element body, any of four positions (upper surface, lower surface and both side surfaces) on the circuit board Can be installed.

  Patent Document 1 discloses a chip resistor as an example of a chip-shaped electronic component. Also in the chip resistor, a cap-shaped end face electrode is formed at both ends of an insulating substrate, and this end face electrode is used as a front electrode. With the configuration of connection, it is possible to mount on four sides on the circuit board.

  Although Patent Document 1 does not specifically describe a specific method for forming the end face electrode, as disclosed in Patent Document 2, for example, while rotating a roller having a conductive paste applied to the outer peripheral surface, If the application method of applying the conductive paste by bringing one surface of the chip body close to the outer peripheral surface of the roller while moving the chip body in the almost same direction as the rotation direction of the roller is adopted, It is possible to suppress variations as much as possible.

JP-A-61-183911 JP, 2003-264117, A

  By the way, in a normal chip resistor, since a protective film covering the resistor is formed on the surface of an insulating substrate made of ceramics, when the cap-shaped end face electrodes are formed on both ends of the insulating substrate as described above, insulation is not required. After forming a protective film on the entire surface of the substrate so as to cover the front electrode and the resistor, it is necessary to wrap the conductive paste from the end surface side of the insulating substrate to the upper surface of the insulating film, the back surface of the insulating substrate, and intermediate positions on both side surfaces. is there.

  However, there is a large difference in the amount of the conductive paste applied from the end surface side of the insulating substrate between the upper surface on which the protective film made of resin is formed and the back surface and both side surfaces where the ceramic surface of the insulating substrate is exposed. Therefore, there is a problem that the cap shape of the end face electrode becomes irregular. In other words, the wraparound amount of the conductive paste is large on the exposed upper surface of the resin and less on the exposed back surface of the ceramic surface, so the electrode dimensions on the front and back surfaces are different, and the electrode shape on the side surface is different. Is pulled to the upper surface side (protective film side) and becomes slanted. As a result, when the chip resistors are mounted on the circuit board with the side surface facing downward, the pair of end face electrodes soldered to the lands of the circuit board face each other in a “C” shape. It becomes impossible to exert the self-alignment effect when the solder paste is cured.

  The present invention has been made in view of the above-mentioned circumstances of the prior art. A first object of the present invention is to provide a chip resistor capable of forming cap-shaped end face electrodes having stable dimensions at both ends of an insulating substrate. To provide. A second object of the present invention is to provide a method of manufacturing such a chip resistor.

In order to achieve the above-mentioned first object, the chip resistor of the present invention comprises a rectangular parallelepiped insulating substrate made of ceramics, and a pair of front electrodes provided on both ends in the longitudinal direction on the surface of the insulating substrate, A resistor connecting the two front electrodes, a protective film made of a resin covering the entire front surface of the insulating substrate including the resistor and the both front electrodes, and an auxiliary resin made of a resin covering the entire back surface of the insulating substrate. A film, and a pair of end face electrodes provided on both end faces in the longitudinal direction of the insulating substrate and electrically connected to the front electrode, the end face electrodes being in the longitudinal direction of both side faces of the protective film, the auxiliary film and the insulating substrate. The both end portions are covered, and the protective film and the auxiliary film are made of the same resin material .

In the chip resistor configured in this way, the protective film covering the entire front surface of the insulating substrate and the auxiliary film covering the entire rear surface of the insulating substrate are both formed of the same resin material, so Thus, the amount of bleeding on the end face electrodes becomes almost the same. Therefore, even with respect to the ceramic surfaces exposed on both sides of the insulating substrate, since the end face electrodes are pulled in the same manner by the protective film and the auxiliary film made of the same material, the size of the end face electrodes is four sides of the rectangular parallelepiped chip resistor ( It is possible to form a cap-shaped end surface electrode having a uniform size on the upper and lower surfaces and both side surfaces and having stable dimensions. Moreover, since the protective film and the auxiliary film are formed of the same resin material, the dimension of the end face electrode can be made more stable.

  Further, in the above-mentioned configuration, when the end face shape of the end face electrode is a square having the same aspect ratio, it becomes a prismatic chip resistor having the same width and thickness dimensions, so that the mounting surface on the circuit board is a chip. It is preferable that all four sides of the resistor are the same.

In order to achieve the above-mentioned second object, a method of manufacturing a chip resistor according to the present invention comprises a step of forming a pair of front electrodes in a plurality of chip forming regions on the surface of a large-sized substrate made of ceramics, and the pair of front electrodes. Forming a resistor so as to connect between the front electrodes forming the substrate, and forming a protective film made of a resin over the plurality of chip forming regions on the surface of the large-sized substrate so as to cover the front electrode and the resistor. And a step of forming an auxiliary film made of resin on the entire plurality of chip formation regions on the back surface of the large-sized substrate, and a primary division line extending in the longitudinal direction through the large-sized substrate through the central portion of the front electrode. A step of forming individual chip elements by cutting with a dicing blade along a secondary division line orthogonal to the primary division line, and the primary division of the chip element. Forming an end surface electrode by applying a conductive paste from the cut surface along the in-subjected part of the cut surface along the secondary distribution lines, seen including, forming the auxiliary layer and the protective layer are the same resin material It is characterized by being.

In this way, the front electrode corresponding to many chip resistors, the resistors and the protective film are formed on the front surface of the large-sized substrate, and the auxiliary film is formed on the back surface of the large-sized substrate, and then the large-sized substrate is divided into individual chips by dicing. When the end face electrodes are formed by applying a conductive paste to the end face side of the chip element after dividing into elements, the protective film covering the entire front surface of the chip element made of ceramics and the auxiliary film covering the entire back surface are both made of the same resin. Since it is made of a material, the amount of bleeding of the end face electrode is almost the same on the front surface and the back surface of the chip element. Therefore, even with respect to the ceramic surfaces exposed on both side surfaces of the chip element, since the end surface electrodes are pulled in the same manner by the protective film and the auxiliary film made of the same material, the size of the end surface electrodes is four sides of the rectangular parallelepiped chip resistor ( Since the upper surface, the lower surface and both side surfaces are uniform and the protective film and the auxiliary film are made of the same resin material, a cap-shaped end surface electrode having a stable dimension can be formed.

  According to the chip resistor and the method of manufacturing the same of the present invention, it is possible to form cap-shaped end face electrodes having stable dimensions on both ends of the insulating substrate.

It is a perspective view of the chip resistor concerning the example of an embodiment of the present invention. It is a top view of this chip resistor. It is sectional drawing which follows the III-III line of FIG. It is sectional drawing which follows the IV-IV line of FIG. Sectional drawing which follows the VV line of FIG. It is explanatory drawing which shows the manufacturing process of this chip resistor. It is explanatory drawing which shows the manufacturing process of this chip resistor.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A chip resistor according to an embodiment of the present invention includes a rectangular parallelepiped insulating substrate 1 and an insulating substrate 1 as shown in FIGS. A pair of front electrodes 2 provided at both ends in the longitudinal direction on the surface of the, a rectangular resistor 3 provided so as to be connected to these front electrodes 2, and insulation including both front electrodes 2 and the resistor 3. The protective film 4 made of a resin covering the entire front surface of the substrate 1, the auxiliary film 5 made of a resin covering the entire back surface of the insulating substrate 1, and the pair of end face electrodes 6 provided at both ends in the longitudinal direction of the insulating substrate 1. It is mainly composed.

  The insulating substrate 1 is made of ceramics, and the insulating substrate 1 is obtained by dicing a large-sized substrate, which will be described later, along primary and secondary dividing lines extending vertically and horizontally.

  The pair of front electrodes 2 is formed by screen-printing an Ag-based paste and then dried and fired. These front electrodes 2 are rectangular so as to be exposed from each end face of the insulating substrate 1 on the short side and both long sides. Is formed in.

  The resistor 3 is formed by screen-printing a resistance paste such as ruthenium oxide and drying and firing, and both ends of the resistor 3 in the longitudinal direction overlap the front electrode 2. Although not shown, the resistor 3 has a trimming groove for adjusting the resistance value.

  The protective film 4 is an overcoat layer obtained by screen-printing an epoxy resin paste and heating and curing it. Although not shown, an undercoat layer covering the resistor 3 is formed below the protective film 4. There is. The undercoat layer was formed by screen-printing a glass paste, followed by drying and firing. Since the protective film 4 is formed so as to cover the entire surface of the insulating substrate 1 including both the front electrodes 2 and the resistor 3, the three end surfaces including the left end of the front electrode 2 located on the left side in FIG. 3 are insulated. It is exposed between the substrate 1 and the protective film 4, and three end faces including the right end of the front electrode 2 located on the right side are exposed between the insulating substrate 1 and the protective film 4.

  The auxiliary film 5 is formed by screen-printing an epoxy resin paste and heat-curing it. It is preferable that the auxiliary film 5 and the above-mentioned protective film 4 are formed of the same resin material.

  The pair of end face electrodes 6 are formed by dip-coating Ag paste or Cu paste and heating and curing. The end face electrodes 6 are formed from both end faces 1a of the insulating substrate 1 to the upper face of the protective film 4 and the lower face of the auxiliary film 5 and the insulating film. It is formed in a cap shape so as to cover both side surfaces 1b of the substrate 1. As a result, the end face electrode 6 located on the left side in FIG. 3 is connected to the three end faces of the left front electrode 2 exposed between the insulating substrate 1 and the protective film 4, and the end face electrode 6 located on the right side is the insulating substrate. It is connected to the three end faces of the right front electrode 2 exposed from between 1 and the protective film 4.

  Although not shown, the pair of end face electrodes 6 are covered with external electrodes, and these external electrodes are formed by electrolytically plating Ni, Sn, etc. on the surface of the end face electrodes 6.

  As described above, in the chip resistor according to the present embodiment, the protective film 4 that covers the entire front surface of the insulating substrate 1 and the auxiliary film 5 that covers the entire rear surface of the insulating substrate 1 are both made of epoxy resin or the like. Since it is made of a material, when the cap-shaped end surface electrodes 6 are formed by coating on both ends of the insulating substrate 1 in the longitudinal direction, the amount of bleeding of the end surface electrodes 6 becomes substantially the same on the front surface and the back surface of the insulating substrate 1. Therefore, even on the ceramic surface exposed on both side surfaces 1b of the insulating substrate 1, since the end face electrode 6 is pulled in the same manner by the protective film 4 and the auxiliary film 5 made of the same material, the size of the end face electrode 6 is a rectangular chip. It is possible to form the cap-shaped end surface electrode 6 which is uniform on the four surfaces (upper surface and lower surface and both side surfaces) of the resistor and has stable dimensions.

  Here, in the chip resistor according to the present embodiment, as shown in FIG. 1, the end face shape of the end face electrode 6 is set to a square having the same aspect ratio, and the width dimension W and the thickness dimension T are made equal. It is a prismatic chip resistor (for example, width dimension W = 0.1 mm, thickness dimension T = 0.1 mm). As a result, the end face electrodes 6 formed on the four faces (the upper face, the lower face, and both side faces) of the chip resistor have the same shape with the same area. Therefore, when mounting the chip resistor having such a shape on the circuit board, Even if any of the four surfaces (top surface, bottom surface, and both side surfaces) of the chip resistor is the mounting surface, the self-alignment effect can be exerted in exactly the same manner.

  Next, a method of manufacturing the chip resistor configured as described above will be described with reference to FIGS. 6 and 7.

  First, as shown in FIGS. 6A and 7A, a large-sized substrate 10 made of ceramics in which a large number of insulating substrates 1 are taken is prepared. Although no primary dividing groove or secondary dividing groove is formed in this large-sized substrate 10, the large-sized substrate 10 is formed into a primary dividing line L1 and a secondary dividing line L2 that extend in the vertical and horizontal directions in the post process shown in FIG. 6 (f). Each of the cells, which are diced along with each other and are divided by the two dividing lines L1 and L2, serve as a chip forming region for one piece. 6 shows a state in which the large-sized substrate 10 is viewed in plan view (only FIG. 6 (e) is a rear view), and FIG. 7 shows a state in which a chip forming region for one in FIG. 6 is cross-sectioned. There is.

  Then, by printing an Ag-based paste on the surface of such a large-sized substrate 10 and drying and baking it, a predetermined interval is formed on the surface of the large-sized substrate 10 as shown in FIGS. 6 (b) and 7 (b). A plurality of pairs of front electrodes 2 that exist and extend in strips are formed.

  Next, a resistor paste such as ruthenium oxide is screen-printed on the surface of the large-sized substrate 10 and is dried and baked to form a pair of front electrodes 2 as shown in FIGS. 6 (c) and 7 (c). A plurality of resistor bodies 3 extending in between are formed. The order of forming the front electrode 2 and the resistor 3 may be reversed.

  Next, in order to reduce damage to the resistor 3 when forming the trimming groove, a glass paste is screen-printed, dried and baked to form an undercoat layer (not shown) covering the resistor 3, A trimming groove is formed in the resistor 3 on the undercoat layer to adjust the resistance value. Then, an epoxy resin paste is screen-printed on the undercoat layer and heat-cured to include the front electrode 2 and the resistor 3 as shown in FIGS. 6 (d) and 7 (d). A protective film 4 is formed to cover the entire chip formation area of the large-sized substrate 10.

  Next, an epoxy resin paste is screen-printed on the back surface of the large-sized substrate 10 and heat-cured, so that the entire chip formation region on the back surface of the large-sized substrate 10 is formed as shown in FIGS. An auxiliary film 5 is formed to cover the.

  After that, as shown in FIG. 6 (f), the large-sized substrate 10 passes through the central portion of the front electrode 2 in the width direction, and the primary dividing line L1 extends in the longitudinal direction. By cutting with a dicing blade along the division line L2, as shown in FIG. 6G, individual chip elements 10A having substantially the same outer shape as the chip resistor are obtained. The peripheral portion of the large-sized substrate 10 is a dummy region surrounding each chip formation region, and this dummy region is discarded as a discarded substrate 10B after dicing. The primary division line L1 and the secondary division line L2 are virtual lines set for the large-sized board 10, and as described above, the primary division groove and the secondary division corresponding to the division line are formed on the large-sized board 10. The groove is not formed.

  Next, a conductive paste such as Ag paste or Cu paste is dip-coated on the end surface of the chip element 10A and heat-cured, so that the chip element 10A is short-sided from both longitudinal end surfaces as shown in FIG. 7 (f). End face electrodes 6 are formed so as to wrap around to predetermined positions on both end faces in the direction. At this time, since the protective film 4 and the auxiliary film 5 covering the two opposite surfaces of the chip element 10A are formed of the same resin material (epoxy resin), the chip on which the protective film 4 and the auxiliary film 5 are formed The amount of bleeding of the end face electrode 6 is substantially the same on the two surfaces of the element 10A. Therefore, even with respect to the ceramic surfaces exposed on the remaining two surfaces of the chip element 10A, since the end face electrodes 6 are similarly pulled by the protective film 4 and the auxiliary film 5 made of the same material, the four surfaces of the rectangular parallelepiped chip element 10A ( It is possible to make the dimensions of the end face electrodes 6 formed on the upper and lower surfaces and both side surfaces uniform.

  Finally, electrolytic plating of Ni, Sn or the like is applied to each chip element 10A to form an external electrode (not shown) covering the end surface electrode 6, and the chip resistor as shown in FIG. 1 is completed. .

  As described above, in the chip resistor manufacturing method according to the present embodiment, the front electrode 2, the resistor 3 and the protective film 4 corresponding to a large number of chip resistors are formed on the surface of the large-sized substrate 10. After forming the auxiliary film 5 on the back surface of the large-sized substrate 10, the large-sized substrate 10 is divided into individual chip elements 10A by dicing, and then a conductive paste such as Ag paste is dip-coated on the end surface side of the chip elements 10A. The end face electrodes 6 are formed. At this time, since the protective film 4 and the auxiliary film 5 covering the two opposite surfaces of the chip element made of ceramics are formed of the same resin material, these protective films 4 are formed. And the amount of bleeding of the end face electrode 6 becomes substantially the same on the two surfaces of the chip element 10A on which the auxiliary film 5 is formed. Therefore, even with respect to the ceramic surfaces exposed on the remaining two surfaces of the chip element 10A, the end face electrodes 6 are similarly pulled by the protective film 4 and the auxiliary film 5 made of the same material, so that the four surfaces of the rectangular parallelepiped chip element 10A ( The size of the end surface electrode 6 is uniform on the upper surface, the lower surface, and both side surfaces, and the cap-shaped end surface electrode 6 having a stable size can be formed.

  Further, in the method of manufacturing the chip resistor according to the present embodiment example, after the front electrode 2, the resistor 3, the protective film 4 and the auxiliary film 5 are formed on the large-sized substrate 10, the large-sized substrate 10 is changed to the primary division line L1. When the chip element 10A is obtained by dicing along the secondary division line L2, the strip-shaped front electrodes 2 are cut in the length direction and the width direction, respectively, and thus are covered with the protective film 4. The cut surface of the exposed front electrode 2 is exposed from the end surface and both side surfaces of the chip element 10A. Therefore, when the end face electrodes 6 are formed on both ends of the chip element 10A after that, the connection points of the front electrode 2 and the end face electrode 6 become not only the end face of the chip element 10A but also three faces including both side faces, and the end face electrode 6 The connection reliability between the front electrode 2 and the front electrode 2 can be greatly improved.

1 Insulating Substrate 2 Front Electrode 3 Resistor 4 Protective Film 5 Auxiliary Film 6 End Face Electrode 10 Large Format Substrate 10A Chip Element L1 Primary Dividing Line L2 Secondary Dividing Line

Claims (3)

A rectangular parallelepiped insulating substrate made of ceramics, a pair of front electrodes provided at both ends in the longitudinal direction on the surface of the insulating substrate, a resistor connecting the two front electrodes, and the resistor and the both front electrodes. And a protective film made of resin covering the entire front surface of the insulating substrate, an auxiliary film made of resin covering the entire back surface of the insulating substrate, and electrically connected to the front electrode provided on both end faces in the longitudinal direction of the insulating substrate. And a pair of end face electrodes, the end face electrodes covering both end portions in the longitudinal direction of both side faces of the protective film and the auxiliary film and the insulating substrate, and the protective film and the auxiliary film are the same resin material. A chip resistor characterized by being formed of . 2. The chip resistor according to claim 1, wherein the end face shape of the end face electrode is a square having the same aspect ratio . A step of forming a pair of front electrodes in a plurality of chip forming regions on the surface of a large-sized substrate made of ceramics,
  Forming a resistor so as to connect between the pair of front electrodes,
  A step of forming a protective film made of resin over the plurality of chip forming regions on the surface of the large-sized substrate so as to cover the front electrode and the resistor;
  A step of forming an auxiliary film made of a resin on the entire plurality of chip forming regions on the back surface of the large-sized substrate,
  The large-sized substrate is cut by a dicing blade along a primary dividing line extending in the longitudinal direction through the central portion of the front electrode, and a secondary dividing line orthogonal to the primary dividing line to cut individual chip elements. Forming process,
  Forming an end face electrode by applying a conductive paste from a cut surface along the primary division line of the chip element to a part of the cut surface along the secondary division line;
And the protective film and the auxiliary film are formed of the same resin material.