JP2009088368A - Method of manufacturing low-resistance chip resistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a low-resistance chip resistor with which reliability can be obtained as an electrode by sufficiently ensuring an overlapping portion of a surface electrode film and an end face electrode film, furthermore, an insulating substrate can be relatively easily divided along a dividing groove and in division, burrs hardly occur. <P>SOLUTION: In a chip resistor 10, the surface electrode film 12 is formed in a triple-layer structure comprising a lower layer 12a, an intermediate layer 12b and an upper layer 12c. The surface electrode film 12 is constituted of a material with copper as a main component. The lower layer 12a is formed so as to be spaced apart from a dividing groove 11b in a secondary direction over a dividing groove 11a in a primary direction, the intermediate layer 12b is formed so as to be spaced apart from the dividing grooves 11a, 11b in the primary and secondary directions and to be thicker than the surface electrode film lower layer 12a and further, the upper layer 12c is formed so as to be spaced apart from the dividing grooves 11a, 11b in the primary and secondary direction and, by providing an end face electrode film 16 and an electrode plating film 17 herein, to be higher than a resistor film 13 and a protecting film 14. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a low resistance chip resistor, and more particularly to a method for manufacturing a low resistance chip resistor to be face-down mounted.

  As a conventional method of manufacturing a chip resistor, first, a surface electrode film is formed so as to straddle the dividing groove on an insulating substrate made of alumina in which the dividing groove is engraved, and then the surface electrode films are connected to each other. Some of them form a resistance film. Here, the surface electrode film is printed on an alumina substrate by a screen printing method using a silver paste in which silver powder, glass powder, a vehicle, a solvent and the like are kneaded, and after drying this, the peak temperature is about 850 ° C. It is formed by firing. The resistance film is formed by screen printing, drying, and baking in the same manner as the surface electrode film, using a resistance paste in which silver powder, palladium powder, glass powder, a vehicle, a solvent, and the like are kneaded.

However, it is not easy to manufacture a chip resistor having a TCR of 300 × 10 ⁻⁶ / ° C. at 50 mΩ or less by the above manufacturing method. In order to realize this, it is conceivable to use a resistance paste having a sheet resistance of 0.1Ω / □ and to form a fired resistive film with a thickness of about 20 μm. There is a problem that the thickness of the vessel becomes thicker than the prescribed dimension. Furthermore, it is necessary to reduce the resistance value of the electrode portion.

In order to solve such a problem, it is considered to apply a copper-based thick film to the surface electrode film and the resistance film.
For example, when a copper-based thick film is applied to achieve a sheet resistance of 2 mΩ / □ with a film thickness of 12 μm, the composition of the paste is, for example, 75% to 85% copper powder, 1% to 5% glass powder, vehicle And 10-24% of solvent. On the other hand, when a conventional silver-based thick film is applied, the composition of the paste is, for example, 70% silver powder, 9% glass powder, 21% vehicle and solvent.
When both are compared, in the copper-based thick film, the content of glass powder decreases by about 5%, while the content of conductive powder (copper powder or silver powder) increases by about 5%. Therefore, by applying a copper-based thick film, the surface electrode film straddling the dividing groove of the insulating substrate is formed as compared with the silver-based thick film, as in the above-described chip resistor manufacturing method. There arises a problem that it becomes difficult to cut the insulating substrate along the groove.

  By the way, in order to reduce the influence of the resistance value of the end face electrode, which becomes a hindrance when realizing a low resistance and low TCR chip resistor, the surface on which the resistance film exists is mounted toward the circuit board component mounting surface. A chip resistor is known, and in such a face-down mounted chip resistor, a resistor film made of a material mainly composed of a copper / nickel alloy is described in Patent Documents 1 and 2. Has been.

  The chip resistor of Patent Document 1 is provided with a pair of raised base portions at both longitudinal ends of the lower surface of the ceramic substrate, and a pair of first electrode layers so as to cover at least a part of these raised base portions, A resistor mainly composed of a copper / nickel alloy is formed so as to bridge the pair of first electrode layers, a second electrode layer is formed so as to cover the pair of first electrode layers, and a resistance A protective layer is provided to cover the body. Further, on both end faces of the ceramic substrate, end face electrodes are respectively formed to connect the upper electrode layer provided on the upper face of the substrate with the first electrode layer and the second electrode layer, and these end face electrodes are covered with a plating layer. It has been broken.

In Patent Document 2, a resistor mainly composed of a copper / nickel alloy having a low resistance and a low TCR is formed on the lower surface of the ceramic substrate, and the first electrode layer and the first electrode layer are formed so as to cover both longitudinal ends of the resistor. A chip resistor is described in which a second electrode layer is provided in a two-layer structure, an insulating protective layer is provided so as to cover the resistor, and upper electrode layers are provided at both ends of the upper surface of the ceramic substrate. The upper electrode layer, the first electrode layer, and the second electrode layer are connected to each other by end face electrodes provided on both end faces of the ceramic substrate.
JP 2007-88161 A JP 2007-88162 A

In paragraph 0018 of Patent Document 1, “the first and second electrode layers 4 and 6 are printed so as not to overlap with the periphery of each chip region. There is little risk of entering the break groove for use ", and there is a similar description in paragraph 0017 of Patent Document 2.
In this way, when the electrode layer material does not enter the dividing break groove, for example, even if the electrode layer is made of a material mainly composed of copper, burrs are not generated when the strip-shaped substrate is formed by primary division. The advantage of not occurring is obtained.
However, when the end face electrode films are formed by sputtering the both end faces of the strip-shaped substrate in which the material of the electrode layer does not enter the breaking break grooves, the edges of the first electrode layer and the second electrode layer are formed. Then, there is a possibility that the overlapping portion with the end face electrode film is reduced. When a sufficient overlapping portion cannot be obtained in this way, the resistance value at the overlapping portion becomes high, and it is difficult to reduce the resistance of the chip resistor.

  An object of the present invention is to solve the above-mentioned problems. The object of the present invention is to sufficiently secure an overlapping portion between the surface electrode film and the end face electrode film, to obtain reliability as an electrode, and to mainly use copper. A method of manufacturing a low-resistance chip resistor in which the insulating substrate along the dividing groove is relatively easy to divide even when the surface electrode film is composed of the component material, and burrs are not easily generated when divided. Is to provide.

  In the present invention, the above problems are solved by means (1) and (2) described below.

(1) From the surface of the insulating substrate in which the primary and secondary dividing grooves are engraved on the front and back surfaces so as to divide into rectangles, straddling the primary dividing grooves and from the secondary dividing grooves A surface electrode film lower layer forming step of forming a surface electrode film lower layer so as to be spaced apart, and spaced apart from the division grooves in the primary and secondary directions of the insulating substrate on the surface electrode film lower layer, and more than the surface electrode film lower layer A surface electrode film intermediate layer forming step for forming a thick surface electrode film intermediate layer, a resistor film forming step for connecting the surface electrode film intermediate layers to each other, and forming a resistor film covering a part of these, A front electrode film upper layer is formed on the electrode film intermediate layer so as to be separated from the primary and secondary dividing grooves of the insulating substrate, not to contact the resistor film, and to be higher than the resistor film. The electrode film upper layer forming step and the resistance value adjustment of the resistor film A trimming groove engraving step for engraving the trimming groove, a protective film forming step for forming a protective film so as to cover the resistor film, and dividing the insulating substrate into strips along the division grooves in the primary direction. A primary division step, an end face electrode film forming step of forming an end face electrode film by a sputtering method so as to cover the left and right end faces of the insulating substrate and overlap each part of the back electrode film and the lower layer of the front electrode film, and the insulating substrate A secondary dividing step of dividing the electrode into a chip shape along the dividing groove in the secondary direction, and an electrode so as to cover the back electrode film, the front electrode film lower layer, the front electrode film intermediate layer, the front electrode film upper layer and the end face electrode film An electrode plating film forming step of forming a plating film, wherein the surface electrode film lower layer, the surface electrode film intermediate layer, the surface electrode film upper layer, and the resistor film are made of glass powder containing at least Cu and SiO ₂ Formed by firing A method of manufacturing a low resistance chip resistor.

  (2) The low resistance chip according to (1), wherein the surface electrode film lower layer is formed to a thickness of 5 to 10 μm, and the surface electrode film intermediate layer is formed to a thickness of 15 to 20 μm. Manufacturing method of resistors.

In the present invention, the thickness of the lower layer of the surface electrode film may be formed thinner than the depth and width of the primary direction dividing grooves on the surface of the insulating substrate, whereby the insulating substrate is formed into the primary direction dividing grooves. It becomes easy to divide along, and the burr | flash which arises in an end surface can be suppressed.
For example, the insulating substrate used as a general-purpose product is one in which the depth of the dividing groove in the primary direction of the surface is about 170 to 230 μm and the maximum width of the dividing groove is about 10 to 30 μm. When such an insulating substrate is used, the thickness of the lower layer of the surface electrode film can be recommended to be about 5 to 10 μm in the production method (2).
In addition, when forming the surface electrode film lower layer by the screen printing method, if the film thickness is too thin, there is a possibility that the printed pattern may be blurred. Considering this, about 5 to 10 μm as described above. It is preferable to use a thick film.

In the method for manufacturing a low resistance chip resistor of the present invention, the surface electrode film lower layer is formed so as to straddle the primary direction dividing grooves formed on the insulating substrate, while the surface electrode film intermediate layer and the surface electrode film Since the upper layer is formed so as to be separated from the dividing grooves in the primary and secondary directions, the surface electrode film having the three-layer structure is formed from a material mainly composed of copper. In addition, it becomes easy to divide the insulating substrate along the dividing grooves in the primary direction, it is possible to suppress burrs generated on the dividing end faces, and further reduce the conductor resistance in the surface electrode film having a three-layer structure, The resistance of the chip resistor can be reduced.
According to the production method of the present invention, the surface electrode film lower layer of the surface electrode film having a three-layer structure is formed thinner than the surface electrode film intermediate layer and the surface electrode film upper layer, and is primary even after the primary division. Since the end surface electrode is left as it is on the surface that was the dividing groove in the direction, the end surface electrode can secure a sufficient overlapping surface with respect to the lower layer of the surface electrode film, and can prevent a decrease in reliability as an electrode. .

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.
FIG. 1 is a cross-sectional view of a chip resistor 10 manufactured according to the present invention.
In the chip resistor 10, a surface electrode film 12 mainly composed of copper is formed from three layers of a lower layer 12a, an intermediate layer 12b and an upper layer 12c on both ends of the surface of an insulating substrate 11 made of alumina or the like. A resistor film 13 mainly composed of copper is formed between the films 12, a trimming groove 13 a is provided in the resistor film 13, and a protective layer 14 mainly composed of an epoxy resin material is formed on the resistor film 13. The back electrode film 15 is formed on both ends of the back surface of the insulating substrate 11, and the end face electrode films 16 are formed on both end surfaces of the insulating substrate 11 so as to connect the back electrode film 15 and the front electrode film lower layer 12a. An electrode plating film 17 made of copper, nickel and tin is formed so as to cover the end face electrode film 16, the back electrode film 15 and the front electrode film 12.

Next, a manufacturing method of the chip resistor of the present invention will be described with reference to FIGS.
2A to 2C are plan views as viewed from the front side of the insulating substrate, and FIGS. 2D to 2F are cross-sectional views taken along line AA in FIG.
First, as shown in FIGS. 2A and 2D, the surface electrode film lower layer 12 a is formed on the surface of the insulating substrate 11.
Split grooves 11a and 11b are formed on the front and back surfaces of the insulating substrate 11 in a primary direction and a secondary direction so as to be divided into rectangles. In particular, the split grooves 11a in the primary direction are formed to a depth of about 200 μm. . Moreover, as a material of the surface electrode film lower layer 12a, it is possible to use a paste containing Cu and SiO _2. More specifically, 75 to 85% of Cu powder and 1 to 5 of glass powder containing SiO ₂ are used. %, Vehicle and solvent can be used in a proportion of about 10 to 24%.
The paste is insulated by the screen printing method with the pattern shown in FIGS. 2A and 2D, that is, a pattern that straddles the dividing groove 11a in the primary direction and is separated from the dividing groove 11b in the secondary direction. The substrate 11 is printed and fired at a peak temperature of about 900 ° C. in a nitrogen atmosphere to form a surface electrode film lower layer 12a having a thickness of about 5 to 10 μm. Since the thickness of the surface electrode film lower layer 12a is extremely thin compared to the depth 200 μm of the dividing groove 11a in the primary direction, the surface electrode film lower layer 12a is divided as shown in FIG. It is formed in a cross-sectional shape along the surface of the groove 11a.

Next, the surface electrode film intermediate layer 12b is formed on the surface electrode film lower layer 12a.
The surface electrode film intermediate layer 12b uses the same paste material as that of the surface electrode film lower layer 12a, and the pattern shown in FIGS. 2B and 2E, that is, the dividing grooves 11a and the secondary in the primary direction are formed by screen printing. It prints with the pattern which leaves | separates from the direction division | segmentation groove | channel 11b, and it bakes at the peak temperature of about 900 degreeC in nitrogen atmosphere, and forms it by about 15-20 micrometers in film thickness. The surface electrode film intermediate layer 12 b has a function of adjusting the distance between the surface electrode films 12 at both ends in accordance with the resistance value of the chip resistor 10.
The surface electrode film intermediate layer 12b is formed with a film thickness larger than that of the surface electrode film lower layer 12a. The thickness of the surface electrode film intermediate layer 12b depends on the allowable range of the resistance value of the surface electrode film 12 itself. As appropriate.

Next, the resistor film 13 is formed as shown in FIGS.
As the material of the resistor film 13, for example, a paste made of a mixed powder or alloy powder of copper powder or nickel powder and lead-free glass, vehicle, or solvent can be used. Such a paste is separated from the pattern shown in FIGS. 2C and 2F by the screen printing method, that is, from the surface electrode film lower layer 12a and the dividing groove 11b in the secondary direction, to form one surface electrode film intermediate layer 12b. And is printed by a pattern that covers the insulating substrate 11 between the surface electrode film intermediate layers 12b and baked at a peak temperature of 900 ° C. in a nitrogen atmosphere.

After the resistor film 13 is formed, as shown in FIG. 3A, a surface electrode film upper layer 12c is formed on the surface electrode film intermediate layer 12b. The surface electrode film upper layer 12c uses the same paste material as the surface electrode film lower layer 12a, is separated from the primary direction division grooves 11a and the secondary direction division grooves 11b by the screen printing method, and also from the resistor film 13 Printing is performed in a distant arrangement, and firing is performed at a peak temperature of about 900 ° C. in a nitrogen atmosphere to form a film thickness of about 10 to 15 μm.
Here, the reason why the surface electrode film upper layer 12c is separated from the resistor film 13 is to prevent the surface of the surface electrode film upper layer 12c from having a height difference due to the overlap, and the chip resistor 10 is suitable for face-down mounting. This is to make it a different shape.
Further, since the surface electrode film upper layer 12c is in contact with the component mounting surface when the chip resistor 10 is face-down mounted on the circuit board, the protective film 14 is formed after the electroplating layer is formed so as to adapt to this. It is formed as an auxiliary to form higher. This is because the lateral dimension of the chip resistor 10 may exceed a prescribed value if it is formed higher than the protective film 14 only by the electroplating layer.
As described above, the surface electrode film 12 is composed of the three-layer structure of the surface electrode film lower layer 12a, the surface electrode film intermediate layer 12b, and the surface electrode film upper layer 12c. The surface electrode film 12 includes the resistor film 13 and the protective film 14. The thickness of the electroplating layer 17 is lower than that of the protective film 14 by forming the electroplating layer 17 having a thickness of 15 to 30 μm. Can be formed. Moreover, since only the relatively thinly formed surface electrode film upper layer 12c is superimposed on the dividing groove 11a in the primary direction, the surface electrode film 12 is formed from a material mainly composed of copper. The insulating substrate 11 can be easily divided in the primary direction.
After the surface electrode film upper layer 12c is formed, the surface of the resistor film 13 is trimmed to form the groove 13a while measuring the resistance value, and the resistor film 13 is adjusted to a desired resistance value.

Next, as shown in FIG. 3B, the protective film 14 and the back electrode film 15 are formed.
The protective film 14 uses a paste material mainly composed of an epoxy resin, covers the resistor film 13 with the trimming grooves 13a formed by screen printing, and fills the gaps between the upper surface electrode film layers 12c at both ends. Print in place and bake at around 200 ° C. The protective film 14 needs to have a sufficient film thickness to cover the trimming groove 13a, and two-layer printing is performed. Thereby, the protective film 14 is formed higher by about 10 to 25 μm than the upper surface electrode layer 12c.
The back electrode film 15 is printed using a conductive resin paste material containing silver as a main component and arranged in such a manner as to straddle the dividing grooves 11a and 11b in the primary direction and the secondary direction by screen printing. Bake at around ℃. The back electrode film 15 is formed so as to straddle the dividing grooves 11a and 11b in the primary direction and the secondary direction because there are few burrs at the time of division and good cracking property compared to the copper-based thick film. The

After forming the protective film 14 and the back electrode film 15, the insulating substrate 11 is divided along the dividing grooves 11 a in the primary direction, thereby forming a strip-shaped intermediate processed product. At this time, only the relatively thinly formed surface electrode film lower layer 12a is superposed on the dividing groove 11a in the primary direction, and therefore the surface electrode film lower layer 12a is formed of a material mainly composed of copper. Nevertheless, the primary substrate can be easily divided in the primary direction, and the generation of burrs is suppressed.
The cross section in the short side direction of the strip-shaped intermediate processed product is shown in FIG. 4A. As shown in this figure, the surface electrode film lower layer 12a wraps around and adheres to the surface that was the dividing groove 11a in the primary direction. ing.

  Next, end face electrodes 16 having a two-layer structure of a chromium film and a nickel film are formed by sputtering on both end faces in the longitudinal direction of the strip-shaped intermediate processed product. FIG. 4B shows a cross section after the end face electrode 16 is formed.

  After the end face electrode 16 is formed, the chip-shaped intermediate processed product is formed by dividing along the secondary-direction dividing groove 11b. Further, the chip-shaped intermediate processed product is formed from a three-layer structure of Cu, Ni, and Sn. When the electroplating layer 17 is formed, the chip resistor 10 is completed. The electroplating layer 17 of Cu, Ni, Sn is formed so as to be about 5 to 20 μm higher than the protective film 14, and when the chip resistor 10 is mounted face-down on the circuit board, the protective film 14 and the circuit board surface A gap is made between them.

It is sectional drawing of the chip resistor manufactured by this invention. (A)-(c) is a top view which shows each process which comprises the manufacturing method of the chip resistor of this invention, (d)-(f) is sectional drawing in these each process. (A) and (b) are sectional drawings which show each process performed following FIG. (A)-(c) is sectional drawing which shows each process performed following FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Chip resistor 11 Insulating substrate 12 Front electrode film 12a Front electrode film lower layer 12b Front electrode film intermediate layer 12c Front electrode film upper layer 13 Resistor film 13a Trimming groove 14 Protective layer 15 Back electrode film 16 End face electrode film 17 Electrode plating film

Claims (2)

The dividing grooves in the primary direction and the secondary direction so as to be divided into rectangles are straddled on the surface of the insulating substrate in which the front and back surfaces are engraved, and are separated from the dividing grooves in the secondary direction. A surface electrode film lower layer forming step of forming a surface electrode film lower layer on the surface;
A surface electrode film intermediate layer forming step of forming a surface electrode film intermediate layer that is spaced apart from the primary and secondary dividing grooves on the surface electrode film lower layer and thicker than the surface electrode film lower layer;
A resistor film forming step of connecting the surface electrode film intermediate layers and forming a resistor film covering a part of these,
On the surface electrode film intermediate layer, the surface electrode film upper layer is formed so as to be separated from the primary and secondary dividing grooves of the insulating substrate, not to contact the resistor film, and to be higher than the resistor film. A surface electrode film upper layer forming step,
A trimming groove engraving step for engraving a trimming groove for adjusting the resistance value of the resistor film;
A protective film forming step of forming a protective film so as to cover the resistor film;
A primary dividing step of dividing the insulating substrate into strips along a dividing groove in a primary direction;
An end face electrode film forming step of forming an end face electrode film by a sputtering method so as to cover the left and right end faces of the insulating substrate and to overlap each of the back electrode film and the front electrode film lower layer;
A secondary division step of dividing the insulating substrate into chips along the division grooves in the secondary direction;
An electrode plating film forming step of forming an electrode plating film so as to cover the back electrode film, the surface electrode film lower layer, the surface electrode film intermediate layer, the surface electrode film upper layer and the end face electrode film,
The low resistance chip resistor, wherein the surface electrode film lower layer, the surface electrode film intermediate layer, the surface electrode film upper layer, and the resistor film are formed by firing a paste material made of glass powder containing at least Cu and SiO _2. Manufacturing method.   2. The low resistance chip resistor according to claim 1, wherein the lower layer of the surface electrode film is formed to a thickness of 5 to 10 μm, and the intermediate layer of the surface electrode film is formed to a thickness of 15 to 20 μm. Production method.

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