WO2014185254A1

WO2014185254A1 - Method for manufacturing chip resistor

Info

Publication number: WO2014185254A1
Application number: PCT/JP2014/061704
Authority: WO
Inventors: 岡　直人
Original assignee: コーア株式会社
Priority date: 2013-05-16
Filing date: 2014-04-25
Publication date: 2014-11-20
Also published as: JP6170726B2; JP2014225568A

Abstract

In order to enable the wraparound of sputtering material on a protective coat to be reliably prevented in a simple manufacturing step, a method for manufacturing a chip resistor (1) involves a previous step in which end surface electrodes (8) are formed, wherein a masking material (11) is formed on an overcoat (a protective coat) (7) in such a manner as to avoid a recess (7a), which is where a trimming groove (10) is formed, and the masking material (11) is removed by ultrasonic cleaning after the sputtering of the end surface electrodes (8).

Description

Manufacturing method of chip resistor

The present invention relates to a method of manufacturing a chip resistor that is surface-mounted on a circuit board by soldering.

This type of chip resistor includes an insulating substrate having a rectangular shape in plan view, a pair of electrode portions provided on the insulating substrate at a predetermined interval, and a resistor that bridges the paired electrode portions, The resistor is mainly composed of an insulating protective coat or the like covering the resistor, and a trimming groove for adjusting a resistance value is formed in the resistor. The electrode portion includes a front electrode, a back electrode, and an end face electrode that bridges both electrodes, and a pair of surface electrodes are bridged by a resistor on the surface side of the insulating substrate.

Usually, when manufacturing such a chip resistor, prepare a large-sized substrate provided with dividing grooves in advance, print and paste silver paste etc. on this large-sized substrate, respectively, on both sides of the large-sized substrate A plurality of pairs of front and back electrodes are formed. Next, a resistor paste is printed on a large substrate and baked to form a plurality of resistors so as to straddle each pair of surface electrodes, and then a glass paste is printed on a region covering the resistors. By baking, an undercoat is formed on each resistor. Next, in order to adjust the resistance value of the resistor, after forming the trimming groove by irradiating the resistor covered with the undercoat with a laser beam, in order to protect the resistor from the external environment, An overcoat (protective coat) is formed so as to cover the entire resistor including the trimming groove. Next, the large-sized substrate is primarily divided into strips along the dividing grooves, and a plurality of the strip-shaped substrates are overlapped. After forming end face electrodes on the entire end surface by sputtering, the strip-shaped substrate is secondarily formed. Dividing (secondary break processing) into individual chips is obtained. Finally, a standardized chip size chip resistor is completed by forming a plating layer on the base electrode layer (surface electrode, back electrode, and end electrode) continuous in a U-shape of a single chip.

However, in a chip resistor manufactured through each of these processes, the sputtered film wraps around the overcoat when stacking a plurality of strip-shaped substrates and forming an end face electrode by sputtering, and such sputtering is performed. Since the dimensions and linearity of the electrodes vary due to the wraparound of the film, there is a problem that the mounting state of the chip resistor mounted on the circuit board cannot be correctly inspected.

Therefore, a conventional method of manufacturing a chip resistor in which a masking material in a paste form is printed and dried on an overcoat that is a protective coating, and after forming an end face electrode by sputtering, the masking material is removed by ultrasonic cleaning. Has been proposed (see, for example, Patent Document 1). According to such a conventional technique, the masking material is formed on the overcoat in the previous step of forming the end face electrode, and this masking material is removed after the sputtering of the end face electrode. Can be prevented, and the state of the sputter end can be made linear.

JP 2004-128218 A

By the way, in this type of chip resistor, after the trimming groove is formed in the resistor before the overcoat formation and the resistance value is adjusted, the overcoat is formed so as to cover the entire resistor including the trimming groove. Therefore, the surface of the overcoat does not become a flat surface but has a recess having the same shape as the trimming groove. For this reason, when the masking material is formed on the entire surface of the overcoat as in the prior art disclosed in Patent Document 1, the masking material enters the concave portion of the overcoat, and the masking material is washed after sputtering of the end face electrodes. In some cases, it becomes difficult to remove the masking material that has entered the recess. If the ultrasonic cleaning is continued for a long time or the power of the ultrasonic wave is increased to increase the power, it is possible to clean even the masking material that has entered the recess. However, in that case, the manufacturing cost increases, the sputtered film Another problem arises in that the yield is poor due to damage.

The present invention has been made in view of the actual situation of the prior art, and an object of the present invention is to provide a chip resistor manufacturing method capable of reliably preventing spattering of a sputter on a protective coat with a simple manufacturing process. Is to provide.

In order to achieve the above object, in the method of manufacturing a chip resistor according to the present invention, an electrode forming step of forming a pair of electrodes on a rectangular insulating substrate, and a resistor so as to straddle the electrodes. A resistor forming step for forming, a trimming forming step for forming a trimming groove for adjusting a resistance value in the resistor, and a protective coat forming step for forming a protective coat so as to cover the entire resistor after the trimming forming step A masking process for masking the protective coat so as to avoid the trimming groove forming part, and an end face electrode forming process for forming an end face electrode connected to the electrode by a sputtering method on the end face of the insulating substrate; And a masking removal step of removing the masking by washing after the end face electrode forming step.

Thus, in the pre-process for forming the end face electrode by sputtering, masking was performed on the protective coat so as to avoid the formation of the trimming groove, and this masking was removed after sputtering of the end face electrode. It is possible to prevent the spattering of the upper part from being masked by masking and to make the state of the sputter end straight. Here, there is a recess with the same shape as the trimming groove on the surface of the protective coat, but masking is formed on the protective coat at a position avoiding this recess, so when removing the mask after sputtering of the end face electrode The masking can be easily removed using ultrasonic cleaning or the like, and the troublesome masking removal work is not required, and the manufacturing process can be simplified.

In such a chip resistor manufacturing method, the mask formed on the protective coat may be frame-shaped so as to surround the portion where the trimming groove is formed. Forming masking at a predetermined position of the protective coat formed on the large-sized substrate before the primary division when the trimming groove forming portion is sandwiched between the pair of masking formed on both ends. Is preferable.

In the manufacturing method of the chip resistor according to the present invention, in the pre-process for forming the end face electrode by sputtering, masking is performed on the protective coat so as to avoid the formation site of the trimming groove, and this masking is removed after the sputtering of the end face electrode. As a result, the spattering of the sputter on the protective coating can be prevented by masking, and the sputter end state can be made linear. In addition, there is a recess having the same shape as the trimming groove on the surface of the protective coat, but since masking is formed on the protective coat at a position avoiding this recess, when removing the masking after sputtering of the end face electrode, Masking can be easily removed using ultrasonic cleaning or the like, and a troublesome mask removing operation is not necessary, thereby simplifying the manufacturing process.

It is a top view of the chip resistor concerning the example of a 1st embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II in 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. It is explanatory drawing which shows the end surface electrode formation process in this manufacturing process. It is explanatory drawing which shows the manufacturing process of the multiple chip resistor which concerns on the example of 2nd Embodiment of this invention.

Hereinafter, embodiments of the invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the chip resistor 1 according to the first embodiment of the present invention includes a rectangular parallelepiped insulating substrate 2 and longitudinal ends of the surface of the insulating substrate 2 (upper surface in FIG. 2). A pair of front surface electrodes 3 provided, a pair of back surface electrodes 4 provided at both ends in the longitudinal direction of the back surface of the insulating substrate 2 (the lower surface in FIG. 2), and a pair of surface electrodes 3 are overlapped and insulated. A resistor 5 provided on the surface of the substrate 2, an undercoat 6 covering the resistor 5, an overcoat 7 covering the undercoat 6, and a pair of bridges between the surface electrode 3 and the back electrode 4 It is mainly comprised by the end surface electrode 8, and the plating layer 9 which coat | covers each back surface electrode 4 and the end surface electrode 8. FIG.

The insulating substrate 2 is made of ceramic or the like, and this insulating substrate 2 is obtained by dividing a large-sized substrate, which will be described later, along a vertical and horizontal dividing groove and taking a large number of them. The front electrode 3 is obtained by screen-printing a silver paste, dried and fired, and the back electrode 4 is also obtained by screen-printing a silver paste, dried and fired. The resistor 5 is a resistor paste such as ruthenium oxide that is screen-printed, dried and fired. A trimming groove 10 is formed in the resistor 5 to adjust the resistance value. The undercoat 6 is obtained by screen-printing and baking a glass paste. The undercoat 6 is formed so as to cover the resistor 5 before the trimming groove 10 is formed. The overcoat 7 is obtained by screen-printing and curing an epoxy resin paste, and this overcoat 7 is formed after the trimming groove 10 is formed in the resistor 5.

The end face electrode 8 is formed by sputtering so as to cover the end face of the insulating substrate 2 and the surface electrode 3, and the end face electrode 8 is a sputter containing adhesion chromium (Cr) to the insulating substrate 2 and a barrier layer material. It consists of a membrane. The barrier layer functions as a cushioning material against thermal stress (heat shock), and nickel (Ni) or copper (Cu) is used. The plating layer 9 is formed by electrolytic plating so as to cover the end face electrode 8, and this plating layer 9 is made of tin (Sn) -lead (Pb), lead-free Sn, or the like.

Next, a method for manufacturing the chip resistor 1 configured as described above will be described with reference to FIGS. The first to tenth steps will be described with reference to FIG. 3, and the eleventh to fifteenth steps will be described with reference to FIG.

First, as a first step, as shown in FIG. 3A, an unfired back electrode 4 is formed by screen-printing and drying Ag paste on the back surface of a large substrate 20 on which a large number of insulating substrates 2 are taken. After the formation, as a second step, an unfired surface electrode 3 is formed by screen-printing and drying an Ag / Pd paste on the surface of the large substrate 20 (electrode formation step). The large-sized substrate 20 is provided with a primary dividing groove and a secondary dividing groove (both not shown) in advance in a lattice shape, and each of the squares divided by both the dividing grooves is equivalent to one. This is the chip area.

Next, after firing the unfired front electrode 3 and back electrode 4 at a high temperature of about 850 ° C. as a third step, a ruthenium oxide resistor paste is screened on the surface of the large substrate 20 as a fourth step. By printing and drying, an unfired resistor 5 is formed in each chip region as shown in FIG. 3B (resistor forming step). At that time, both ends in the longitudinal direction of the resistor 5 are overlapped with the surface electrodes 3 provided at both ends in the longitudinal direction of each chip region. In the next fifth step, the resistor 5 is fired at a high temperature of about 850 ° C. Note that the firing of the third step described above may be omitted, and the front electrode 3, the back electrode 4 and the resistor 5 may be fired simultaneously in this fifth step. In this case, the firing step is reduced to reduce the cost. Is possible.

Next, after the glass paste is screen-printed on the region covering the resistor 5 and dried in the sixth step, the glass paste is baked at a high temperature of about 600 ° C. in the seventh step, so that FIG. As shown in FIG. 2, an undercoat 6 is formed on the resistor 5. This undercoat 6 is for preventing the vicinity of the trimming groove 10 of the resistor 5 from being damaged by the heat of the laser beam irradiated in the next step.

Next, as an eighth step, as shown in FIG. 3D, the trimming groove 10 is formed by irradiating the resistor 5 covered with the undercoat 6 with a laser beam (trimming forming step). At that time, probes not shown are brought into contact with the surface electrodes 3 existing on both sides in the longitudinal direction of the resistor 5 to be trimmed, and laser trimming is performed while measuring the resistance value through these probes. When the laser beam irradiation is started and the trimming groove 10 becomes longer, the resistance value increases accordingly. Therefore, when the resistance value of the resistor 5 to be trimmed reaches a desired value, the laser beam irradiation is performed. Turn off.

Next, as a ninth step, an epoxy resin paste is screen-printed in a region covering the undercoat 6 and then heat-cured at about 200 ° C., so that the resistor 5 is shown in FIG. Then, an overcoat 7 covering the undercoat 6 and the trimming groove 10 is formed (protective coat forming step). At this time, since the resin paste printed on the undercoat 6 also enters the trimming groove 10, the surface of the overcoat 7 after heat curing is not a flat surface, and the trimming groove 10 is located near the center of the overcoat 7. A concave portion 7a having the same shape as that is formed. The overcoat 7 is for protecting the resistor 5 from the external environment.

Next, as a tenth step, a water-soluble epoxy resin is screen-printed in a region avoiding the recess 7a on the overcoat 7 and dried, thereby forming the recess 7a on the overcoat 7 as shown in FIG. A pair of strip-shaped masking materials 11 that are opposed to each other are formed (masking forming step). The end portions on the surface electrode 3 side of these masking materials 11 are parallel to the longitudinal end portions of the overcoat 7, and the masking material 11 is removed in the completed state of the chip resistor 1 as will be described later.

The process up to this point is a batch process for the large-sized substrate 20 for taking a large number of pieces, but in the next eleventh step, a primary break process is performed in which the large-sized substrate 20 is divided into strips along the first dividing groove. . Thereby, a strip-shaped substrate 30 provided with a plurality of chip regions is obtained.

Then, in the next twelfth step, a plurality of strip-shaped substrates 30 are stacked in the vertical direction, and Cr / Ni is sputtered on the end surfaces of the strip-shaped substrates 30 in this state, as shown in FIG. Next, the end face electrode 8 that bridges the front electrode 3 and the back face electrode 4 is formed (end face electrode forming step). In this case, the masking material 11 on the overcoat 7 of the lower strip-shaped substrate 30 is sputtered in a state of being in contact with the lower surface of the upper strip-shaped substrate 30, and a sputtered film is also formed between the strip-shaped substrates 30 overlapping vertically. In order to wrap around, the end surface electrode 8 is formed from the end surface of the strip-shaped substrate 30 to the end portion of the overcoat 7 and the end portion of the masking material 11 beyond the surface electrode 3. However, as shown in FIG. 5, since the masking material 11 is in contact with the lower surface of the upper strip-shaped substrate 30, the sputtered film does not reach the recess 7 a beyond the masking material 11. FIG. 5 shows an end face electrode forming process when five strip-shaped substrates 30 are stacked and sputtered, and one of them corresponds to the strip-shaped substrate 30 shown in FIG.

Thereafter, as a thirteenth step, a secondary break process is performed in which the strip-shaped substrate 30 is divided along the second divided grooves, and a piece (chip alone) having the same size as the chip resistor 1 is obtained.

Next, as a fourteenth step, the masking material 11 formed on the overcoat 7 is removed as shown in FIG. (Masking removal process). At this time, since the masking material 11 does not enter the recess 7a on the overcoat 7, the masking material 11 can be easily cleaned and removed without applying a strong ultrasonic wave for a long time.

Finally, as a fifteenth step, the plating is performed so as to cover the back surface electrode 4 and the end surface electrode 8 as shown in FIG. Layer 9 is formed to complete the chip resistor 1 as shown in FIGS.

As described above, in the method of manufacturing the chip resistor 1 according to this embodiment, the masking material 11 is formed on the overcoat (protective coat) 7 in the previous step of forming the end face electrode 8. Since the masking material 11 is removed by ultrasonic cleaning after sputtering of the end face electrode 8, the masking material 11 can prevent the sputtering film from wrapping around the overcoat 7, and the state of the sputter end can be made linear. can do. In addition, since the masking material 11 is formed on the overcoat 7 so as to avoid the recess 7a, which is the formation site of the trimming groove 10, when the masking material 11 is removed by ultrasonic cleaning after the end face electrode 8 is sputtered, bother. It can be easily removed without applying a strong ultrasonic wave for a long time, and the troublesome masking removal work is not necessary, thereby simplifying the manufacturing process.

Further, in this embodiment, a pair of masking materials 11 are formed in a strip shape at the longitudinal ends of the overcoat 7 covering the connection portion between the surface electrode 3 and the resistor 5, and the center sandwiched between the masking materials 11 is formed. Since the formation site (recess 7a) of the trimming groove 10 is located in the region, the masking material 11 is easily and accurately formed at a predetermined position of the overcoat 7 formed on the large substrate 20 before the primary division. Can do.

In the above embodiment, both the split surface of the strip-shaped substrate 30 and the surface electrode 3 are covered with the end face electrode 8 and the end face electrode 8 is formed by sputtering. For example, the front face electrode 3 is covered. Only a portion may be formed by a sputtered film, and a thick film may be formed on the divided surface of the strip-shaped substrate 30 using transfer printing or the like. Alternatively, the surface electrode 3 and the back electrode 4 are formed as end faces 8 that are continuous in a U-shape, and these are all formed of a sputtered film, or only the portion covering the front electrode 3 and the back electrode 4 is formed of a sputtered film. You may do it.

Next, a second embodiment in which the present invention is applied to a multiple chip resistor will be described with reference to FIG. The multiple chip resistor according to the present embodiment is a quadruple type chip resistor that is integrally provided in a state where four resistance elements are separated on an insulating substrate. 20 is provided with a number of chip formation regions.

FIG. 6 is an explanatory diagram corresponding to the plan view on the right side of FIG. In the manufacturing method of the multiple chip resistor according to the present embodiment example, the process until the overcoat 7 is formed on the large substrate 20 is the same as that of the first embodiment example, but is formed in the next masking formation process. The shape of the masking material 11 is different from that of the first embodiment. As shown in FIG. 6, the masking material 11 is formed in a comb-like shape so as to protrude between the adjacent surface electrodes 3. Yes. As a result, when the end face electrode is formed by sputtering on the divided surface of the strip-shaped substrate after the primary break, the sputtered film is formed so as to cover the protrusion 11a of the masking material 11, so that the printing pattern of the masking material 11 is changed. With a simple configuration that is devised, it is possible to reliably prevent a short circuit between adjacent surface electrodes 3.

DESCRIPTION OF SYMBOLS 1 Chip resistor 2 Insulating substrate 3 Front surface electrode 4 Back surface electrode 5 Resistor 6 Undercoat 7 Overcoat (protective coat)
7a Concavity (formation part of trimming groove)
8 End face electrode 9 Plating layer 10 Trimming groove 11 Masking material 11a Protrusion 20 Large format substrate 30 Strip substrate

Claims

An electrode forming step of forming a pair of electrodes on a rectangular insulating substrate;
Forming a resistor so as to straddle between the electrodes; and
A trimming formation step of forming a trimming groove for adjusting a resistance value in the resistor;
A protective coat forming step of forming a protective coat so as to cover the entire resistor after the trimming forming step;
Masking forming step of masking on the protective coat so as to avoid the formation site of the trimming groove;
An end face electrode forming step of forming an end face electrode connected to the electrode by a sputtering method on the end face of the insulating substrate;
A masking removal step of removing the masking by washing after the end face electrode forming step;
A method of manufacturing a chip resistor, comprising:
2. The mask according to claim 1, wherein the masking is formed on both ends of the resistor, which is a connection portion with the electrode, and the trimming groove forming portion is sandwiched between the pair of masking. A manufacturing method of a chip resistor.