JP4227821B2 - Manufacturing method of chip resistor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a chip resistor in which a large-sized ceramic substrate is obtained by dividing a large-sized ceramic substrate along a plurality of primary division grooves and secondary division grooves extending in a lattice shape.
[0002]
[Prior art]
A conventional example known as a manufacturing method of this type of chip resistor will be described with reference to FIG. 5. First, as shown in FIG. 5A, vertical and horizontal grids are formed on the upper surface of a large-sized ceramic substrate 20. A plurality of primary dividing grooves 21 and secondary dividing grooves 22 extending in a straight line are formed. These dividing grooves 21 and 22 may be formed by embossing or the like before firing of the ceramic substrate 20, or may be formed on the fired ceramic substrate 20 by laser scribing or dicing. Next, as shown in FIG. 5B, upper surface electrodes (surface electrodes) 23 are respectively formed at positions across the primary division grooves 21 between adjacent secondary division grooves 22. Similarly, a lower surface electrode (back surface electrode) (not shown) is formed in a region corresponding to the upper surface electrode 23 on the lower surface of the ceramic substrate 20. Next, as shown in FIG. 5C, the resistor 24 is formed in each region surrounded by the vertical and horizontal dividing grooves 21 and 22 on the upper surface of the ceramic substrate 20 so that both end portions overlap the upper surface electrode 23. . Since the resistance values of the resistors 24 distributed on the ceramic substrate 20 can be measured by bringing the probes into contact with the upper surface electrodes 23 at both ends thereof, they are trimmed so as to have a desired resistance value. . Thereafter, as shown in FIG. 5 (d), each resistor 24 is covered with an overcoat layer 25, and then the ceramic substrate 20 is broken along the primary dividing grooves 21 to form strip-shaped divided pieces 26. Then, after forming end face electrodes (not shown) on both side surfaces along the longitudinal direction of the strip-shaped divided pieces 26, the strip-shaped divided pieces 26 are broken along the secondary divided grooves 22 to form individual chips (not shown). As a result, by plating the electrode portions of these single chips, a large number of chip resistors (not shown) which are finished products can be manufactured at once.
[0003]
However, when miniaturization of the chip resistor manufactured in this way is promoted, the upper surface electrode 23 and the resistor 24, which are screen-printed using different masks on the large-sized ceramic substrate 20, are displaced. Since it easily occurs, the area where the upper surface electrode 23 and the resistor 24 overlap each other in each region surrounded by the vertical and horizontal dividing grooves 21 and 22 greatly varies, and therefore the trimming operation of each resistor 24 becomes complicated. The problem that productivity deteriorates occurs.
[0004]
Therefore, as another conventional example, on a large ceramic substrate, after forming a plurality of strip electrodes arranged in a stripe extending in a straight line and a plurality of resistors bridging between adjacent strip electrodes, There has been proposed a chip resistor manufacturing method in which a plurality of dividing grooves extending in a vertical and horizontal grid pattern are formed by dicing or laser scribing (see, for example, Patent Document 1).
[0005]
In this case, the primary dividing groove is formed so as to extend in the longitudinal direction through substantially the center in the width direction of each band electrode, and the secondary division groove crosses the plurality of band electrodes along the width direction to form each band electrode. Is divided into a plurality of upper surface electrodes. In this case, since the upper surface electrode always exists on both sides of each region surrounded by the vertical and horizontal dividing grooves, even if the upper surface electrode and the resistor are slightly misaligned, In this case, the area where the upper electrode and the resistor overlap each other is almost constant, and variation in resistance value is suppressed. Therefore, the trimming operation of each resistor can be performed efficiently, and improvement in productivity can be expected.
[0006]
[Patent Document 1]
JP-A-9-115706 (pages 2 and 3, FIG. 1)
[0007]
[Problems to be solved by the invention]
As in the conventional example described above, if a method of forming a dividing groove after forming a strip electrode and a resistor on a large ceramic substrate is employed, variation in resistance value is achieved even if chip resistors are reduced in size. Therefore, the trimming work of each resistor is made more efficient, but on the other hand, the residue generated when the vertical and horizontal dividing grooves are engraved in the strip electrode stays in the dividing grooves and is short-circuited. Since it tends to be a factor, there is a risk that the resistance value cannot be accurately measured prior to trimming. That is, whether dicing performed using a diamond blade or laser scribing performed by irradiating a laser beam, when a dividing groove is engraved in a strip electrode, a residue as an electrode material is placed in the dividing groove. When the dividing groove becomes narrower as the chip resistor is reduced in size, the adjacent upper surface electrodes that should have been insulated through the dividing groove are short-circuited with a conductive residue as a bridge. The possibility that it will end up increases. Therefore, there is a problem that an error is likely to occur in the resistance value of the manufactured chip resistor and it is difficult to obtain high reliability.
[0008]
The present invention has been made in view of such a state of the prior art, and an object of the present invention is to provide a method of manufacturing a chip resistor that has good productivity and easily secures high reliability.
[0009]
[Means for Solving the Problems]
In order to achieve the above-described object, in the method of manufacturing a chip resistor according to the present invention, a plurality of linearly extending plurality of chip resistors corresponding to a large number of chip resistors are linearly provided on the surface of the large-sized ceramic substrate. A plurality of strip-like electrodes so that a bisector extending in the longitudinal direction passing through the center in the width direction on the surface of the ceramic substrate substantially coincides with the primary dividing groove; A strip electrode forming step to be formed, and a plurality of strips extending linearly at predetermined intervals on the surface of the ceramic substrate so as to be perpendicular to the primary dividing grooves so as to divide each strip electrode into a plurality of upper surface electrodes. A secondary divided groove forming step for forming the secondary divided groove, and a resistor forming step for forming a plurality of resistors so as to bridge the upper surface electrodes adjacent to each other along a direction orthogonal to the primary divided groove And each of the above A resistor trimming step for adjusting the resistance value of the antibody; and a break step for sequentially breaking the ceramic substrate along the primary dividing groove and the secondary dividing groove after the resistor trimming step, In the groove forming step, the divided grooves formed by the first laser beam irradiation are irradiated with the second laser beam to form the secondary divided grooves, and the first laser beam irradiation is performed during the second laser beam irradiation. By forming a groove that is wider and shallower than that at the time of laser light irradiation, a chamfered portion with a gentler slope than that at the back of the groove is formed on the opening end side of the divided groove formed by the first laser light irradiation. did.
[0010]
When the technique of performing laser scribing twice when forming the secondary divided groove for dividing each strip electrode into a plurality of upper surface electrodes in this way, the conductive material is formed in the divided grooves formed by the first laser beam irradiation. Since the residue is removed by the second laser beam irradiation, there is no fear that the upper surface electrodes are short-circuited by using the residue as a bridge, and the resistance of each resistor prior to trimming is reduced. Value measurement can always be performed accurately. In addition, since the strip electrode is divided into a plurality of upper surface electrodes, the area where the upper surface electrode and the resistor overlap in each region surrounded by the vertical and horizontal dividing grooves is almost constant, thereby suppressing variations in resistance value. The trimming operation of each resistor can be performed efficiently. In addition, a groove that is wider and shallower than that at the first laser light irradiation is set to be formed at the second laser light irradiation, and the first laser light irradiation is performed by the second laser light irradiation. Since the chamfered portion with a gentler slope than the depth side of the groove is formed on the opening end side of the engraved dividing groove, the strip electrode or ceramic substrate adjacent to the dividing groove becomes slightly brittle by the first laser light irradiation. Even so, the fragile portion can be removed by the second laser beam irradiation, and the edge portion of the manufactured chip resistor is less likely to be chipped. Therefore, it is possible to efficiently manufacture a highly reliable chip resistor with little resistance error.
[0011]
In such a manufacturing method, the primary dividing groove may be formed by laser scribing in the same manner as the secondary dividing groove, but may be formed by embossing before firing the ceramic substrate. However, considering that the end face of the ceramic substrate that breaks and is exposed along the primary dividing groove is the forming face of the end face electrode connected to the upper surface electrode, the strip electrode forming step should be performed after the primary dividing groove forming step. Is preferred.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIGS. 1 and 2 are explanatory views showing a method of manufacturing a chip resistor according to the present embodiment in order of steps, and FIG. The process until formation is shown, and FIG. 2 shows the process after the resistor is formed. FIG. 3 is a cross-sectional view of the finished chip resistor, and FIG. 4 is a cross-sectional view of a main part taken along line AA in FIG.
[0014]
First, the configuration of the chip resistor 10 shown in FIG. 3 will be described. In this chip resistor 10, a resistor 12 and a pair of upper surface electrodes 13 overlapping both ends of the resistor 12 are provided on the upper surface of a ceramic substrate 11 made of alumina or the like, and as a protective film. A glass coat layer 14 covering the resistor 12 and an overcoat layer 15 covering the glass coat layer 14 are provided. A pair of lower surface electrodes 16 are provided in a region corresponding to the upper surface electrode 13 on the lower surface of the ceramic substrate 11, and the upper surface electrode 13 and the lower surface electrode 16 are bridged on both end surfaces in the longitudinal direction of the ceramic substrate 11. An end face electrode 17 is provided. The upper surface electrode 13, the lower surface electrode 16 and the end surface electrode 17 constitute a base electrode layer of the chip resistor 10, and this base electrode layer has two layers, a nickel plating layer 18 and a solder plating layer (or tin plating layer) 19. It is covered with a plating layer.
[0015]
The manufacturing method of the chip resistor 10 configured as described above will be described with reference to FIGS. 1 and 2. First, the ceramic substrate 1 is formed by firing a green sheet made of alumina or the like. This ceramic substrate 1 is a large-sized substrate that is divided into a large number of ceramic substrates 11 of chip resistors 10 in a later step. Then, laser scribing to irradiate the upper surface of the ceramic substrate 1 with laser light is performed to form a plurality of primary division grooves 2 extending linearly at predetermined intervals as shown in FIG. (Primary division groove forming step). The primary dividing grooves 2 may be formed by embossing before firing the ceramic substrate 1.
[0016]
Next, a paste such as Ag or Ag-Pd is screen-printed on the upper surface of the ceramic substrate 1 and fired to form a plurality of strips arranged in stripes extending linearly as shown in FIG. The electrode 3 is formed (upper surface side strip electrode forming step). Here, each strip electrode 3 is set so that a bisector extending in the longitudinal direction through the center in the width direction substantially coincides with the primary dividing groove 2. Similarly, a strip-shaped electrode (not shown) having the same shape is formed in the region corresponding to the strip-shaped electrode 3 by screen-printing and baking a paste such as Ag or Ag-Pd on the bottom surface of the ceramic substrate 1 (bottom surface side). Strip electrode forming step). Any of these upper and lower strip electrodes may be formed first.
[0017]
Thereafter, by performing the first laser scribing in a direction orthogonal to the primary dividing groove 2 (direction crossing the strip electrode 3 in the width direction), a predetermined interval is maintained as shown in FIG. Then, a plurality of narrow divided grooves 4a extending in a straight line are formed, and then a second laser scribing is performed so as to trace each narrow divided groove 4a. The narrow divided groove 4a is finished into a slightly wider secondary divided groove 4 (secondary divided groove forming step). At that time, the distance between the focal position of the laser beam and the ceramic substrate 1 is adjusted as appropriate, and a groove that is wider and shallower than that at the first laser scribe is formed at the second laser scribe. As shown in FIG. 4, the secondary dividing groove 4 has a cross-sectional shape having a chamfered portion 4b on the opening end side. That is, by performing laser scribing twice, a chamfered portion 4b having a gentler inclination than the groove rear side is formed on the opening end side of the narrow divided groove 4a, and the secondary divided groove 4 having a slightly wider width is finished. Since the secondary divided grooves 4 formed in this way extend across the band-shaped electrode 3 in the width direction, each band-shaped electrode 3 is divided into a plurality of upper surface electrodes 13 by this secondary divided groove forming step. Further, there is a possibility that the residue of the strip-shaped electrode 3 stays in the narrow dividing groove 4a carved by the first laser scribe, but the residue is removed by the second laser scribe. There is no fear that the upper surface electrodes 13 are short-circuited by using the residue as a bridge.
[0018]
Next, a resistance paste such as ruthenium oxide is screen-printed on the upper surface of the ceramic substrate 1 and baked, thereby being positioned between adjacent secondary divided grooves 4 as shown in FIG. A plurality of resistors 12 whose portions overlap with the upper surface electrode 13 are formed (resistor forming step). However, this resistor forming step may be performed before the secondary divided groove forming step or the strip electrode forming step, and during the first laser scribe and the second laser scribe in the secondary divided groove forming step. It is also possible to perform a resistor forming step.
[0019]
Next, after a glass coat layer 14 for covering each resistor 12 is formed on the upper surface of the ceramic substrate 1 by screen printing and firing, a probe (not shown) is brought into contact with the upper surface electrode 13 to determine the resistance value of each resistor 12. Measurement is performed, and each resistor 12 is laser trimmed based on the measured value. Thereby, the resistance value of each resistor 12 is adjusted by the trimming groove 5 shown in FIG. 2B (resistor trimming step). As described above, since there is a very low possibility that a conductive residue that short-circuits the adjacent upper surface electrodes 13 exists in the secondary dividing groove 4, the resistance value of each resistor 12 prior to laser trimming. Measurements can always be made accurately.
[0020]
Next, an overcoat layer 15 that covers the glass coat layer 14 and the trimming grooves 5 is formed on the upper surface of the ceramic substrate 1 by screen printing and firing, and then the ceramic substrate 1 is broken along the primary division grooves 2. Then, a strip-shaped divided piece 6 as shown in FIG. 2C is obtained (primary breaking step). Note that the strip electrode on the lower surface side of the ceramic substrate 1 is divided into two equal parts along the primary dividing groove 2 by this primary breaking step. Thereafter, by sputtering Ni—Cr or the like on each of the side end faces along the longitudinal direction of the strip-shaped segment 6, end face electrodes 17 that bridge the upper surface electrodes 13 and the lower side strip electrodes are formed on the side end faces. Form (end face electrode forming step).
[0021]
Next, by breaking the strip-shaped divided pieces 6 along the secondary divided grooves 4, a large number of single chips 7 as shown in FIG. 2D are obtained (secondary breaking step). By this secondary breaking step, the strip-like electrode on the lower surface side is divided into the lower electrode 16 and the ceramic substrate 11 is formed. Then, a large number of single chips 7 are collectively plated to form two-layered plating layers 18 and 19 that cover the base electrode layer (upper surface electrode 13, lower surface electrode 16, and end surface electrode 17). (Plating layer forming step). Thereby, a large number of finished chip resistors 10 as shown in FIG. 3 can be manufactured at once.
[0022]
In this way, in the manufacturing process of the chip resistor 10, when the technique of performing laser scribing twice when forming the secondary division grooves 4 that divide each strip electrode 3 into a plurality of upper surface electrodes 13 is adopted for the first time. Even if a conductive residue stays in the narrow divided groove 4a carved by the laser beam irradiation, the residue is removed by the second laser beam irradiation. There is no fear of being short-circuited, and it is possible to always accurately measure the resistance value of each resistor 12 prior to trimming. Therefore, an error is less likely to occur in the resistance value of the manufactured chip resistor 10, and the reliability is improved. In addition, when the method of dividing the strip electrode 3 into the plurality of upper surface electrodes 13 by the secondary dividing grooves 4 in this way is adopted, both sides of each region surrounded by the vertical and horizontal dividing grooves 2 and 4 on the upper surface of the ceramic substrate 1. Since the upper surface electrode 13 always exists in the portion, even if the upper surface electrode 13 and the resistor 12 are slightly misaligned, the area where the upper surface electrode 13 and the resistor 12 overlap in each region is as follows. It becomes almost constant and variation in resistance value is suppressed. Therefore, trimming work for adjusting the resistance value can be performed efficiently, and improvement in productivity can be expected.
[0023]
In the present embodiment, the chamfered portion 4b is formed on the opening end side of the narrow divided groove 4a formed by the first laser light irradiation by the second laser light irradiation performed in the secondary divided groove forming step. Therefore, even if the belt-like electrode 3 and the ceramic substrate 1 adjacent to the narrow dividing groove 4a become slightly brittle by the first laser light irradiation, this fragile portion can be removed by the second laser light irradiation. . Therefore, chipping is less likely to occur at the edge portion of the manufactured chip resistor 10, and there is no fear of hindering automatic mounting or the like.
[0025]
In the above embodiment, the case where the strip electrode forming process is performed after the primary split groove forming process has been described. However, the primary split groove 2 can be formed by laser scribing or the like after the strip electrode 3 is formed. is there. However, in that case, the strip electrode 3 is adjacent to the primary division groove 2 and the portion connected to the end face electrode 17 in the subsequent process becomes slightly brittle. Therefore, in order to prevent a decrease in reliability, the primary division groove formation step Also, it is preferable to remove the fragile portion of the strip electrode 3 by performing laser scribing twice.
[0026]
【The invention's effect】
The present invention is implemented in the form as described above, and has the following effects.
[0027]
In the manufacturing process of the chip resistor, when forming the secondary divided groove for dividing each strip electrode into a plurality of upper surface electrodes, laser scribing is performed twice, and conductive is conducted in the divided groove formed by the first laser light irradiation. Even if a residual residue remains, the residue can be removed by the second laser beam irradiation, so that short-circuiting between the top electrodes due to the residue is surely prevented. The resistance value of the resistor can always be measured accurately. In addition, since the strip electrode is divided into a plurality of upper surface electrodes, the area where the upper surface electrode and the resistor overlap in each region surrounded by the vertical and horizontal dividing grooves is almost constant, thereby suppressing variations in resistance value. The trimming operation of each resistor can be performed efficiently. In addition, a groove that is wider and shallower than that at the first laser light irradiation is set to be formed at the second laser light irradiation, and the first laser light irradiation is performed by the second laser light irradiation. Since the chamfered portion with a gentler slope than the depth side of the groove is formed on the opening end side of the engraved dividing groove, the strip electrode or ceramic substrate adjacent to the dividing groove becomes slightly brittle by the first laser light irradiation. Even so, the fragile portion can be removed by the second laser beam irradiation, and the edge portion of the manufactured chip resistor is less likely to be chipped. Therefore, it is possible to efficiently manufacture a highly reliable chip resistor with little resistance error.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory diagram showing processes until a secondary dividing groove is formed in a manufacturing process of a chip resistor according to an embodiment of the present invention.
FIG. 2 is an explanatory view showing a process after a resistor is formed in the manufacturing process of the chip resistor.
FIG. 3 is a cross-sectional view of a finished product of the chip resistor.
FIG. 4 is a cross-sectional view of a main part taken along line AA in FIG.
FIG. 5 is an explanatory view showing a method of manufacturing a chip resistor according to a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ceramic substrate 2 Primary division | segmentation groove | channel 3 Band-shaped electrode 4 Secondary division | segmentation groove | channel 4a Narrow division | segmentation groove | channel 4b Chamfering part 5 Trimming groove | channel 6 Strip-shaped division | segmentation piece 7 Chip single-piece | unit 10 Chip resistor 11 Ceramic base body 12 Resistor 13 Upper surface electrode 14 Glass coating Layer 15 Overcoat layer 16 Lower surface electrode 17 End surface electrode 18, 19 Plating layer

Claims (2)

A primary divided groove forming step of forming a plurality of primary divided grooves extending linearly on the surface of a large ceramic substrate corresponding to a large number of chip resistors, with a predetermined interval;
A strip electrode forming step of forming a plurality of strip electrodes so that a bisector extending in the longitudinal direction passing through the center in the width direction on the surface of the ceramic substrate substantially matches the primary dividing groove;
A plurality of secondary divided grooves extending linearly at predetermined intervals are formed on the surface of the ceramic substrate so as to divide each strip electrode into a plurality of upper surface electrodes. Secondary dividing groove forming step;
A resistor forming step of forming a plurality of resistors so as to bridge the upper surface electrodes adjacent to each other along a direction orthogonal to the primary dividing groove;
A resistor trimming step for adjusting the resistance value of each resistor;
A break step of sequentially breaking the ceramic substrate along the primary division grooves and the secondary division grooves after the resistor trimming step;
In the secondary divided groove forming step, the second divided groove is formed by performing the second laser light irradiation on the divided groove formed by the first laser light irradiation, and this second laser light irradiation. Sometimes, by forming a groove that is wider and shallower than at the time of the first laser light irradiation, a chamfered portion with a gentler slope than the groove rear side is formed at the opening end side of the divided groove formed by the first laser light irradiation. A method of manufacturing a chip resistor, characterized in that it is formed .   2. The method of manufacturing a chip resistor according to claim 1, wherein the strip electrode forming step is performed after the primary dividing groove forming step.

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