JP4036464B2 - Chip resistor with low resistance value - Google Patents

Description

The present invention is, for example, relates to a chip resistor having a low resistance value as hereinafter 1 [Omega.

  Conventionally, this type of chip resistor has been described in, for example, as disclosed in Japanese Patent Application Laid-Open No. 2001-118701 and the like. A metal having a higher resistance than the metal of the base material (hereinafter referred to as a high-resistance metal), such as nickel, to a rectangular parallelepiped. Among the resistors, connection terminal electrodes are provided at both left and right ends along the longitudinal direction of the rectangular parallelepiped for soldering to a printed circuit board or the like, and at least between the connection terminal electrodes of the resistors. The part is covered with an insulator.

  In this type of chip resistor, the resistance value between the two connection terminal electrodes largely depends on the specific resistance of the alloy constituting the resistor, and the specific resistance of the alloy is higher than that of the high resistance metal. The ratio is low in proportion to the ratio of the low-resistance metal to the high-resistance metal so that the ratio is low when the ratio of the low-resistance metal is large and increases as the ratio of the high-resistance metal to the low-resistance metal increases. It increases in proportion to the ratio of high resistance metal to metal.

For this reason, in the conventional chip resistor, when the length dimension along the longitudinal direction of the rectangular parallelepiped of the resistor and the width dimension perpendicular to the longitudinal direction are determined in advance, both the connections are made. To lower the resistance value between the terminal electrodes, that is, the resistance value of the chip resistor,
(1). The alloy is an alloy in which the ratio of the low resistance metal to the high resistance metal is reduced.
(2). The plate thickness dimension of the resistor is increased.
Either one or both of these are employed.

  However, it is generally known that metal materials have a temperature coefficient of resistance that the resistance varies with temperature, and this temperature coefficient of resistance is higher for pure metals than for alloys. Yes.

  Therefore, in order to reduce the resistance value of the chip resistor, it is necessary to increase the proportion of the low-resistance metal (base metal) in the alloy constituting the resistor as in (1). Since this alloy approaches the purity of the low-resistance metal (base metal), there is a problem that the temperature coefficient of resistance in the chip resistor is increased.

  Further, in order to reduce the resistance value in the chip resistor, increasing the thickness of the resistor in the resistor as in (2) only increases the weight of the chip resistor. Alternatively, it is difficult to bend the both ends of the resistor in the longitudinal direction to the connection terminal electrode, and trimming adjustment for adjusting the resistance value to a predetermined value by engraving a trimming groove on the resistor is performed. There is a problem that it becomes extremely difficult.

  On the other hand, the temperature coefficient of resistance in metal materials is positive in the case of most pure metals, but in the case of an alloy in which a plurality of these pure metals are alloyed, a negative resistance temperature coefficient is given to some of the alloys. If an alloy having this negative resistance temperature coefficient is used for the resistor, this negative resistance temperature coefficient appears as a negative resistance temperature coefficient as it is in the chip resistor. That was also a problem.

It is a technical object of the present invention to provide a chip resistor that solves these problems.

In order to achieve this technical problem, claim 1 of the present invention provides:
“In a chip resistor comprising a resistor formed in a rectangular parallelepiped with an alloy of a high resistance metal and a low resistance metal, and connection terminal electrodes provided on both ends of the back surface of the resistor,
On the surface of the resistor, a plating layer made of a pure metal having a lower resistance than the alloy constituting the resistor is formed, and the connection terminal electrode is made of a metal having a resistance lower than that of the alloy constituting the resistor. A portion of the resistor between the connection terminal electrodes is provided with a partial reduced portion of the cross-sectional area, and the partial reduced portion of the cross-sectional area is filled with the plating layer. further, the portion between the two connecting terminal electrode of the back surface of the resistor is covered with an insulator. "
It is characterized by that.

Claim 2 in the present invention includes:
“In claim 1, the alloy constituting the resistor has a negative resistance temperature coefficient.”
It is characterized by that.

Claim 3 in the present invention includes:
“In the first or second aspect of the invention, a portion of the plated layer on the surface of the resistor is provided with a portion that is divided into left and right portions or a portion that is narrowed .”
It is characterized by that.

  As described above, a plated layer of pure metal having a resistance lower than that of the alloy is formed on the surface of a resistor made of an alloy of a high resistance metal and a low resistance metal, while the resistor is formed on both ends of the back surface. By providing a connection terminal electrode made of a metal having a lower resistance than that of the alloy constituting the metal alloy, the resistance value between the two connection terminal electrodes is higher than that in the case where the resistor is made of only the alloy, And it is lowered by the amount of both low-resistance connection terminal electrodes.

  Thus, the resistance value between the two connection terminal electrodes, that is, the resistance value in the chip resistor can be obtained without increasing the ratio of the low-resistance metal to the high-resistance metal in the alloy constituting the resistor, and Since the plate thickness in the resistor can be lowered without increasing the thickness, the resistance temperature coefficient is reduced when the resistance value in the chip resistor is lowered with the same length and width dimensions. It is possible to reliably avoid the increase, the trimming adjustment of the resistance value and the bending process of the connection terminal electrode, and the increase in weight.

In this case, in addition to the above-described configuration, a partial reduction portion of the cross-sectional area is provided in a portion between the connection terminal electrodes of the resistor, and the partial reduction portion of the cross-sectional area is The resistance value in the chip resistor can be further lowered by adopting a configuration in which it is filled with the plating layer.

Since the resistance temperature coefficient in the pure metal plating layer is generally positive, as described in claim 2, by making the resistor made of a metal alloy having a negative resistance temperature coefficient, Since the negative resistance temperature coefficient in this resistor can be offset by the positive resistance temperature coefficient in the plating layer formed on the surface of this resistor, is it possible to avoid the appearance of a negative resistance temperature coefficient in the chip resistor? Alternatively, the negative resistance temperature coefficient appearing in the chip resistor can be reduced.

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

  1 and 2 show a chip resistor 1 according to a first embodiment.

  The chip resistor 11 includes a resistor 12 formed in a rectangular parallelepiped having a length dimension of L, a width dimension of W, and a thickness dimension of T, and connection terminal electrodes fixed to both ends of the lower surface of the resistor body 12. 13, an upper surface insulator 14 that covers the entire upper surface of the resistor 12, and a lower surface insulator 14 ′ that covers a portion of the lower surface of the resistor 12 between the connection terminal electrodes 13.

  The resistor 12 is formed on a base metal having a low resistance (hereinafter referred to as a low resistance metal) such as a copper / nickel alloy, a nickel / chromium alloy, or an iron / chromium alloy. It is made of an alloy formed by adding a metal having a higher resistance than the metal of the material (hereinafter referred to as a high resistance metal).

  On the other hand, both connection terminal electrodes 13 are made of an alloy having a lower resistance than the alloy constituting the resistor 12 or a metal made of a pure metal such as copper.

  A plated layer 15 made of pure metal such as copper or silver having a lower resistance than the alloy constituting the resistor 12 is formed on the entire surface of the resistor 12.

  By forming this plating layer 15, as in the case of the first embodiment, the resistance value between the connection terminal electrodes 13 is higher than that in the case where the resistor 12 is made of only an alloy. Therefore, the resistance value between the connection terminal electrodes 13, that is, the resistance value in the chip resistor 11, is reduced by the metal constituting the resistor 12. It is possible to reduce the alloy without increasing the ratio of the low-resistance metal to the high-resistance metal and without increasing the thickness T of the resistor 12.

  The resistance value of the chip resistor 11 is formed by dividing the plating layer 15 formed on the surface of the resistor 12 by a length S as shown in FIG. 3, or by forming a narrow width as shown in FIG. By doing so, the resistance value can be arbitrarily set by the plating layer 15 so that it can be increased.

In addition to the above-described configuration, as shown in FIGS. 5 and 6, at least one slit groove 17 extending laterally from the longitudinal side surface is formed in the portion of the resistor 12 between the connection terminal electrodes 13. The sectional area of the resistor 12 is partially reduced by providing a through hole or the like, and a partially reduced portion of the sectional area such as the slit groove 17 or the through hole is provided as a resistor. It is configured to be filled with a plating layer 15 formed on the surface of 12.
Thereby, the resistance value in the chip resistor 11 can be set to a lower and minute resistance value.

  By the way, since the resistance temperature coefficient of the pure metal of the plating layer 15 is generally positive, the pure metal plating layer 15 having the positive resistance temperature coefficient is made of, for example, 43 to 45 wt% of nickel and the rest. By forming the resistor 12 made of an alloy metal having a negative resistance temperature coefficient such as a copper-nickel alloy of copper, the negative resistance temperature coefficient in the resistor 12 is applied to the surface of the resistor 12. Since the positive resistance temperature coefficient in the formed plating layer 15 can be offset, it is possible to avoid the negative resistance temperature coefficient from appearing in the chip resistor 11 or to reduce the negative resistance temperature coefficient appearing in the chip resistor 11. it can.

  In manufacturing the chip resistor 11 according to the above embodiment, the following method can be employed.

  That is, first, as shown in FIGS. 7 and 8, there is prepared a resistor alloy plate B1 in which a large number of the resistors 12 are aligned in the vertical and horizontal directions, and this resistor alloy plate B1 is prepared. A laminated material metal plate B is manufactured by overlapping and joining a connecting terminal electrode metal plate B2 for forming the connecting terminal electrode 13 on the lower surface of the metal plate, and the resistor alloy in the laminated material metal plate B is manufactured. A plated layer 15 made of pure metal is formed on each of the resistor elements 12 on the upper surface of the plate B1.

  Next, as shown in FIG. 9 and FIG. 10, in the connection terminal electrode metal plate B2 in the laminated material metal plate B, the portions of the connection terminal electrodes 13 at both ends of the resistor 12 are left, and the other portions are replaced. Remove by cutting or the like.

  Next, as shown in FIGS. 11 and 12, the entire upper surface of the resistor alloy plate B1 of the laminated material metal plate B is covered with the upper surface insulator 14, while the lower surface of the resistor alloy plate B1 is covered. Of these, the portion between the connection terminal electrodes 13 is covered with a lower surface insulator 14 '.

Finally, the laminated material metal plate B is cut along a vertical cutting line B ′ and a horizontal cutting line B ″ partitioning each resistor 12, so that FIGS. The chip resistor 11 having the structure shown in FIG.

  Further, in this manufacturing method, the step of forming the plated layer 15 of pure metal on the upper surface of the resistor alloy plate B1 in the laminated material metal body B includes the metal for connection terminal electrodes in the laminated material metal body B. You may make it carry out after the process of removing parts other than the connection terminal electrode 13 among board B2 by cutting.

It is a perspective view which shows the chip resistor by embodiment of this invention. FIG. 2 is a sectional view taken along line II-II in FIG. 1. It is a perspective view which shows the 1st modification in the said chip resistor. It is a perspective view which shows the 2nd modification in the said chip resistor. It is a fragmentary top view which shows the 3rd modification in the said chip resistor. FIG. 6 is a sectional view taken along line VI-VI in FIG. 5. It is a perspective view which shows the 1st process at the time of manufacture of the said chip resistor. FIG. 8 is an enlarged sectional view taken along line VIII-VIII in FIG. 7. It is a perspective view which shows the 2nd process at the time of manufacture of the said chip resistor. FIG. 10 is an enlarged sectional view taken along line XX in FIG. 9. It is a perspective view which shows the 3rd process in the case of manufacture of the said chip resistor. FIG. 12 is an enlarged sectional view taken along line XII-XII in FIG. 11.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Chip resistor 12 Resistor 13 Connection terminal electrode 14 Upper surface insulator 14 'Lower surface insulator 15 Plating layer

Claims (3)

In a chip resistor comprising a resistor formed in a rectangular parallelepiped with an alloy of a high resistance metal and a low resistance metal, and connection terminal electrodes provided at both ends of the back surface of the resistor,
On the surface of the resistor, a plating layer made of a pure metal having a lower resistance than the alloy constituting the resistor is formed, and the connection terminal electrode is made of a metal having a resistance lower than that of the alloy constituting the resistor. A portion of the resistor between the connection terminal electrodes is provided with a partial reduced portion of the cross-sectional area, and the partial reduced portion of the cross-sectional area is filled with the plating layer. Further, a chip resistor having a low resistance value is characterized in that a portion between the two connection terminal electrodes in the back surface of the resistor is covered with an insulator.   2. The chip resistor having a low resistance value according to claim 1, wherein the alloy constituting the resistor has a negative temperature coefficient of resistance.   3. The low-pitch layer according to claim 1, wherein a portion of the surface of the resistor in the plated layer is provided with a portion that is divided into left and right portions or a portion that is narrowed. A chip resistor having a resistance value.

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