JP2019117824A - Chip resistor and manufacturing method thereof - Google Patents

Abstract

To provide a chip resistor and a manufacturing method thereof capable of suppressing peeling of a protective film from a pair of electrodes.SOLUTION: A chip resistor according to the present invention includes a resistor body 11, a pair of electrodes 12 formed on both ends of the surface 11a of the resistor body 11 so as to face each other, and a protective film 13 formed between the electrodes 12 on one surface 11a of the resistor body 11, and the pair of electrodes 12 have projecting portions 15 projecting in directions facing each other, and a part of the protective film 13 is present between the projecting portions 15 and the resistor body 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a chip resistor in which a metal plate used in various electronic devices is a resistor and a method of manufacturing the same.

  A conventional chip resistor of this type, as shown in FIG. 5, includes a resistor 1 made of metal, a pair of square electrodes 2 formed on both ends of one surface 1a of the resistor 1, and a resistor The protective film 3 formed between the pair of electrodes 2 on one surface 1 a of the body 1 and the plated layer 4 formed from the exposed surface of the pair of electrodes 2 to the end face of the resistor 1 were provided.

  As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

Japanese Patent Application Publication No. 2007-49207

  The conventional chip resistor has a problem that the adhesion between the protective film 3 and the pair of electrodes 2 is poor, so that the protective film 3 may be separated from the pair of electrodes 2 due to thermal shock or the like. It was

  The present invention solves the above-mentioned conventional problems, and it aims at providing a chip resistor which can control that a protective film exfoliates from an electrode, and its manufacturing method.

  The chip resistor according to the first aspect includes a resistor, a pair of electrodes formed to face each other at both ends of one surface of the resistor, and a portion between the pair of electrodes on one surface of the resistor. And a protruding portion projecting toward the pair of electrodes facing each other, and a portion of the protective film is present between the protruding portion and the resistor. Do.

  In the chip resistor according to the second aspect, in the first aspect, the thickness of the protrusion decreases as it approaches the pair of electrodes facing each other.

  In the chip resistor according to the third aspect, in the second aspect, the protrusion has an opposite surface on the side away from one surface of the resistor, and the opposite surface of the protrusion is one of the protective films. I am in contact with the department.

  In the chip resistor according to the fourth aspect, in the third aspect, the opposite surface of the protrusion has a tapered surface that approaches one surface of the resistor as it approaches the pair of electrodes facing each other.

A method of manufacturing a chip resistor according to a fifth aspect includes the steps of: forming a resist on the upper surface of a sheet-like resistor; forming a plurality of grooves in the resist; and forming the upper surface of the resist in the plurality of grooves. A step of forming an electrode portion having a convex portion positioned further upward and having a portion extending in a lateral direction orthogonal to the groove along the upper surface of the resist, a step of peeling the resist, and the sheet Forming a protective film on the upper surface of the resistor to cover the electrode portion, and polishing the upper portion of the protective film and a portion of the convex portion to leave a lower portion of the convex portion of the electrode portion And removing.

  Since a pair of electrodes has a projection projecting toward the pair of opposing electrodes, the anchor effect can suppress peeling of the protective film from the pair of electrodes, and further approaches the pair of opposing electrodes In accordance with the above, the thickness of the projecting portion is reduced, so that the contact area between the protective film and the pair of electrodes is increased, whereby the adhesion strength between the protective film and the pair of electrodes can be increased. It produces an effect.

Cross-sectional view of chip resistor in one embodiment Sectional view showing the method of manufacturing the same chip resistor Sectional view showing the method of manufacturing the same chip resistor Cross-sectional view of a chip resistor as a comparative example Cross-sectional view of a conventional chip resistor

  FIG. 1 is a cross-sectional view of a chip resistor in one embodiment.

  The chip resistor in the embodiment of the present disclosure is formed so as to face each other at both ends of one surface (upper surface) 11 a of the resistor 11 made of metal and the resistor 11 as shown in FIG. The pair of electrodes 12, the protective film 13 formed between the pair of electrodes 12 on the upper surface 11a of the resistor 11, the plating layer 14 formed from the upper surface of the pair of electrodes 12 to the end surface 11c of the resistor 11 Is equipped.

  In the above configuration, the resistor 11 is a substantially rectangular solid elongated in the direction of current (X direction), and is made of a metal having a relatively high electric resistivity and a low TCR, such as nichrome, copper nickel, manganin, etc. There is.

  The resistor 11 is formed of a metal plate having an upper surface (one surface) 11 a and a lower surface (other surface) 11 b spaced in the thickness direction.

  Further, the pair of electrodes 12 are provided on both ends of the upper surface 11 a of the resistor 11 so as to face each other (opposite in the direction of the current (X direction)), and have an electrical resistivity (specific resistance) from the resistor 11. It is composed of metals such as copper, silver, etc. which have low TCR and high height. The pair of electrodes 12 is composed of a thick film material or plating.

  At the uppermost portion of the pair of electrodes 12 (the portion farthest from the upper surface 11a of the resistor 11 in the vertical direction Y), a projecting portion 15 projecting toward the pair of electrodes 12 opposed in the X direction is integrally formed It is done. Note that a portion of the protective film 13 is formed between the protrusion 15 and the resistor 11 and is not in direct contact with each other.

  As the protrusion 15 approaches the pair of electrodes 12 facing the X direction (side of the other electrode 12), the position of the upper surface 15a in the Y direction gradually decreases, and the thickness t1 in the Y direction decreases. To go. The lower surface 15 b of the protrusion 15 is substantially parallel to the upper surface 11 a of the resistor 11 and also in contact with the protective film 13.

The upper surface 15a of the protrusion 15 is an opposite surface away from the upper surface 11a of the resistor 11 in the Y direction, and the lower surface 15b is a surface facing the upper surface 11a of the resistor 11 in the Y direction.

  The upper surface (opposite surface) 15a of the protrusion 15 has a tapered surface that approaches the upper surface 11a of the resistor 11 as it approaches the pair of electrodes 12 facing in the X direction.

  As shown in FIG. 1, the shape of the upper surface 15a of the protrusion 15 is an arc when viewed from the cross-sectional direction (the upper side of the drawing), and the thickness t1 of the end is zero. That is, the upper surface 15a of the protrusion 15 is an arc-shaped taper, and the end surfaces of the protrusion 15 facing each other are arc-shaped in the cross-sectional direction.

  The upper surface 15a of the projecting portion 15 may not be in the shape of a circular arc but may be another shape such as a linear shape, but the area in the cross sectional direction is larger when the circular arc is formed than in the linear shape. The connection area is increased, which is more preferable.

  Further, the entire shape of the combination of at least a part of the upper surfaces of the pair of electrodes 12 and the upper surface 15 a of the protrusion 15 may be an arc shape.

  The protective film 13 is formed between the pair of electrodes 12 on the upper surface 11 a of the resistor 11 and is made of a thick film material made of epoxy resin or the like.

  In the Y direction, the height of the protective film 13 is substantially equal to the height of the pair of electrodes 12. That is, the upper surface of the protective film 13 is flush with the uppermost surfaces of the pair of electrodes 12. The protective film 13 is also formed on the upper surface of the portion where the position of the upper surface 15 a of the protrusion 15 in the Y direction is lowered.

  The plating layer 14 is integrally formed from the end face 11 c of the resistor 11 to the upper surfaces of the pair of electrodes 12. The plating layer 14 is made of nickel plating or tin plating, and is provided to improve solderability. The plating layer 14 may be formed only on the pair of electrodes 12.

  Here, the surface on which the pair of electrodes 12 are formed is mounted on a mounting substrate (hereinafter not shown). Here, the direction of mounting on the mounting substrate (the pair of electrodes 12 side) is referred to as “upper” for convenience.

  Hereinafter, a method of manufacturing a chip resistor according to an embodiment of the present invention will be described with reference to the drawings.

  First, as shown in FIG. 2A, a sheet-like resistor 21 in which a metal is formed in a plate shape is prepared, and a resist 22 is attached to the upper surface of the sheet-like resistor 21.

  Next, as shown in FIG. 2B, a part of the resist 22 is peeled in a strip shape to form a plurality of grooves 23 in the resist 22. The plurality of grooves 23 are substantially parallel to each other and formed at equal intervals.

  Next, as shown in FIG. 2C, the sheet-like resistor 21 in the groove 23 exposed from the resist 22 is plated with silver to form an electrode 24. The electrode portion 24 corresponds to the pair of electrodes 12 of the chip resistor in the form of a piece.

  The electrode portion 24 includes a portion filling the inside of the groove portion 23 and a convex portion 24 a formed above the upper surface of the resist 22. In addition, it extends in the lateral direction (direction orthogonal to the groove 23) along the upper surface of the resist 22.

  Next, as shown in FIG. 2D, the resist 22 is peeled off.

  Next, as shown in FIG. 3A, a protective film 25 is formed on the upper surface of the sheet-like resistor 21 so as to completely cover the electrode portion 24. The protective film 25 is made of epoxy resin and then cured. The protective film 25 corresponds to the protective film 13 of the piece-like chip resistor.

  Next, as shown in FIG. 3B, the upper portion of the protective film 25 and a part of the convex portion 24a are polished and removed so as to leave the lower portion of the convex portion 24a of the electrode portion 24.

  Next, as shown in FIG. 3C, the electrode portion 24 and the sheet-like resistor 21 are cut at the central portion (broken line portion in the figure) of each electrode portion 24 and divided into pieces. The cut sheet-like resistor 21 corresponds to the piece-like resistor 11.

  Further, Ni plating and Sn plating are performed from the upper surface of the pair of electrodes 12 of the chip resistor in the form of a piece to the end surface 11 c of the resistor 11 to form the plating layer 14.

  In order to simplify the description, FIGS. 2 and 3 show a portion in which two grooves 23 are formed.

  Furthermore, the resistance value may be adjusted appropriately. When adjusting the resistance value, a portion of the resistor 11 is cut by laser to form a trimming groove.

  In the chip resistor in the above-described embodiment, since the protruding portions 15 which project in the opposite direction of the pair of electrodes 12 are present, peeling of the protective film 13 from the pair of electrodes 12 is suppressed by the anchor effect. The effect of being able to

  Furthermore, since the thickness t1 is made thinner so that the position of the upper surface 15a of the protrusion 15 becomes lower toward the pair of electrodes 12 facing each other, the end surfaces of the protrusions 15 facing each other in the cross-sectional direction The contact area between the protective film 13 and the pair of electrodes 12 is increased as compared to the case of linear shape.

  Further, since the lower surface 15b of the projection 15 is also in contact with the protective film 13, the contact area between the protective film 13 and the pair of electrodes 12 is increased, thereby increasing the adhesion strength between the protective film 13 and the pair of electrodes 12 be able to. As a result, peeling of the protective film 13 from the pair of electrodes 12 can be more effectively suppressed.

  And since the lower surface 15b of the protrusion part 15 is comprised substantially parallel to the upper surface 11a of the resistor 11, an anchor effect increases.

  Furthermore, since a part of the protective film 13 is formed on the upper surface (opposite surface) 15a of the projecting part 15, the contact area between the protective film 13 and the pair of electrodes 12 is further increased to further increase the adhesion strength. Can.

  Further, as described above, when forming the electrode portion 24, after providing the convex portion 24a at a position located above the upper surface of the resist 22 and extending in the lateral direction (direction orthogonal to the groove portion 23), Since the polishing is performed halfway to the protrusion 24 a, the protrusion 15 can be easily formed.

Furthermore, it is also easy to gradually lower the position of the upper surface 15a of the protrusion 15 as it approaches the pair of electrodes 12 opposed in the X direction, and to make the thickness t1 thinner.

  Here, as shown in FIG. 4, with the configuration in which the height of the upper surface 15 a of the protrusion 15 in the Y direction is left unchanged (the same height as the upper surfaces of the pair of electrodes 12), a pair of electrodes 12 facing in the X direction The thickness t1 of the protrusion 15 may be made thinner as it approaches.

In this case, the contact area between the protective film 13 and the pair of electrodes 12 is increased by the arc-shaped taper, and the contact area between the protective film 13 and the pair of electrodes 12 is increased. However, it is necessary to form the plating layer 14 not only on the upper surfaces of the pair of electrodes 12 but also on the upper surfaces 15 a of the protrusions 15 and mount them on the lands of the mounting substrate.

  Then, the land length of the mounting substrate has to be increased, and there is a possibility that the land length of the mounting substrate needs to be changed. On the other hand, in the configuration shown in FIG. 1, the entire length of the upper surfaces of the pair of electrodes 12 can be kept as it is, so that a conventional mounting substrate can be used.

  Further, as shown in FIG. 1, when the upper surface (opposite surface) 15 a of the protrusion 15 is in contact with a part of the protective film 13, the protective film 13 is prevented from peeling off from the pair of electrodes 12. The effect is greater.

  Another protective film may be formed on the lower surface 11 b of the resistor 11, and a resin substrate may be attached to the lower surface 11 b of the resistor 11.

  The chip resistor according to the present invention and the method of manufacturing the same have the effect of suppressing peeling of the protective film from the pair of electrodes, and in particular, a chip using a metal plate used as a resistor in various electronic devices. It becomes useful by applying to a resistor etc.

11 resistor 12 pair of electrodes 13 protective film 15 protrusion

Claims (5)

A resistor, a pair of electrodes formed to face each other at both ends of one surface of the resistor, and a protective film formed between the pair of electrodes on the one surface of the resistor; The tip resistor which has a projecting part which protrudes toward the said pair of electrodes which oppose in an electrode, and a part of said protective film exists between the said projecting part and the said resistor. The chip resistor according to claim 1, wherein the thickness of the protrusion decreases as it approaches the pair of opposing electrodes. The chip resistor according to claim 2, wherein the protrusion has an opposite surface remote from the one surface of the resistor, and the opposite surface of the protrusion is in contact with a part of the protective film. The chip resistor according to claim 3, wherein the opposite surface of the protrusion has a tapered surface that approaches one surface of the resistor as it approaches the pair of opposing electrodes. The step of forming a resist on the upper surface of the sheet-like resistor, the step of forming a plurality of grooves in the resist, and the plurality of grooves having convex portions located above the upper surface of the resist A step of forming an electrode portion having a portion extending in a lateral direction orthogonal to the groove along the upper surface, a step of peeling the resist, and protection to cover the electrode portion on the upper surface of the sheet resistor A method of manufacturing a chip resistor comprising the steps of: forming a film; and polishing and removing an upper portion of the protective film and a portion of the convex portion so as to leave a lower portion of the convex portion of the electrode portion.