JP2008244211A - Manufacturing method for thin-film chip resistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a thin-film chip resistor that can be manufactured at low cost and is excellent in reliability. <P>SOLUTION: A manufacturing method for a thin-film chip resistor includes a step to form many top electrodes 12 by printing and baking organic metal paste on the top surface of a sheet-like insulating substrate, a step to cover at least a part of many top electrodes 12 and to form many thin-film resistors 13 to be electrically connected with many top electrodes 12, and a step to form many inorganic protection films 14 to cover many thin-film resistors 13. A metal mask consisting of 42 alloy is mounted on the top surface of the sheet-like insulating substrate to form the thin-film resistors 13 with mask sputter. Subsequently, the inorganic protection films 14 are formed with the mask sputter continuously without removing the metal mask. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a thin film chip resistor used in various electronic devices.

  In recent years, with the downsizing and cost reduction of electronic devices, there is an increasing demand for downsizing and cost reduction of mounted electronic components. As chip resistors are also being miniaturized, there is an increasing demand for providing thin film chip resistors with high accuracy and excellent current noise characteristics at low cost.

  As shown in FIG. 7, the conventional thin film chip resistor includes a pair of back electrodes 2 formed on both ends of the back surface of the insulating substrate 1 made of alumina having a purity of about 96%, and both end portions of the top surface of the insulating substrate 1. A pair of upper surface electrodes 3, a resistor 4 formed by sputtering so as to be electrically connected to the pair of upper surface electrodes 3, and a protective film 5 (a first film covering the part of the resistor 4) A protective film 5a, a second protective film 5b, a third protective film 5c) and the upper surface of the insulating substrate 1 so as to be in electrical contact with the upper surface electrode 3 and the resistor 4 and in contact with the protective film 5. A pair of resurfaced electrodes 6 made of silver-based resin formed on both ends of the insulating substrate 1 and a pair of resurfaced electrodes 6 formed on both ends of the insulating substrate 1 so as to electrically connect the resurfaced electrode 6 and the backside electrode 2 The end face electrode 7, the end face electrode 7, the re-upper face electrode 6, and the front A nickel plating layer 8 formed on the exposed portion of the back electrode 2 had a structure in which a tin plating layer 9 covering the nickel plating layer 8.

For example, Patent Documents 1 and 2 are known as prior art document information relating to the invention of this application. In the conventional thin film chip resistor described in Patent Document 1, only the resistor 4 is formed of a thin film, and other main components, that is, the back surface electrode 2, the top surface electrode 3, the retop surface electrode 6, and the end surface electrode Since No. 7 is formed by a thick film process using a conductive paste, it has a feature that it can be manufactured at a lower cost than a case where all the constituent elements are formed of a thin film.
JP 2002-640002 A JP 2005-223272 A

  However, in the conventional thin film chip resistor described in Patent Document 1, the resistor 4 is formed as a thin film using a photolithography process, and an insulating material such as alumina is formed on the surface of the resistor 4 by a thin film. Thus, since the first protective film 5a is formed, it is necessary to install a mask pattern separately in each of the resistor 4 forming process and the first protective film 5a forming process. It was complicated. Further, Patent Document 2 discloses a technique in which a metal mask is provided on the upper surface of a sheet-like insulating substrate and the resistor 4 is formed by mask sputtering. The technique disclosed in Patent Document 2 is disclosed. And the technique of Patent Document 1 described above, a metal mask is formed on the upper surface of the sheet-like insulating substrate, and the resistor 4 is formed by mask sputtering. Thereafter, the metal mask is removed without removing the metal mask. By utilizing this, the first protective film 5a can be formed by mask sputtering, and according to this, the manufacturing process can be simplified. However, in this case, the metal mask used in the mask sputtering process is generally made of stainless steel as described in Patent Document 2, and this stainless steel is a heat-resistant insulation that forms a sheet-like insulating substrate. Since the thermal expansion coefficient is larger than that of ceramic such as alumina, which is a material, when this metal mask is repeatedly used in the process of forming the resistor 4 and the process of forming the first protective film 5a, the metal The mask is deformed in response to the thermal history, and as a result, the displacement of the metal mask is likely to occur, and the position where the pattern of the resistor 4 is formed is also likely to be displaced. There is a problem that the electrical connection is not sufficiently guaranteed and the yield of the product is deteriorated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a thin film chip resistor that can be manufactured at low cost and is excellent in reliability.

  In order to achieve the above object, the present invention has the following configuration.

  According to a first aspect of the present invention, there is provided a step of forming a plurality of upper surface electrodes by printing and baking an organic metal paste on an upper surface of a sheet-like insulating substrate, and at least a part of the plurality of upper surface electrodes. And forming a plurality of thin film resistors so as to be electrically connected to the plurality of upper surface electrodes, and forming a plurality of inorganic protective films so as to cover the plurality of thin film resistors, Printing a conductive resin paste so as to cover the plurality of upper surface electrodes and curing the conductive resin paste; and printing a thermosetting resin paste so as to cover the plurality of inorganic protective films. Forming a plurality of organic protective films by curing, and forming a plurality of back electrodes by printing and curing a conductive resin paste on the back surface of the sheet-like insulating substrate; and A step of obtaining a strip-shaped substrate by dividing a strip-shaped insulating substrate, and conductive so as to be electrically connected to the end surface of the strip-shaped substrate with the upper surface electrode, the upper surface electrode, and the rear surface electrode. Forming an end face electrode by applying and curing a resin paste, placing a metal mask composed of 42 alloy on the upper surface of the sheet-like insulating substrate, and forming the thin film resistor by mask sputtering. Subsequently, the inorganic protective film was formed by mask sputtering without removing the metal mask, and according to this manufacturing method, the metal mask was composed of 42 alloy having a smaller thermal expansion coefficient than stainless steel. Even if the metal mask is repeatedly used for the formation of the thin film resistor and the inorganic protective film, the metal mask will not be deformed due to the thermal history. Since the displacement of the metal mask is less likely to occur, the formation position of the thin film resistor is no longer shifted. This ensures reliable electrical connection between the upper surface electrode and the thin film resistor. This has the effect that an excellent thin film chip resistor can be obtained at low cost.

  As described above, in the method of manufacturing a thin film chip resistor according to the present invention, a metal mask composed of 42 alloy is placed on the upper surface of a sheet-like insulating substrate to form a thin film resistor by mask sputtering, and then the metal mask. An inorganic protective film is formed by mask sputtering without removing the metal mask, and the metal mask is composed of 42 alloy having a thermal expansion coefficient smaller than that of stainless steel. Even if it is repeatedly used for forming the protective film, the metal mask will not be deformed due to the thermal history, and as a result, the metal mask is less likely to be displaced. This ensures that the electrical connection between the upper surface electrode and the thin film resistor is ensured, so that it is excellent in reliability. Thin film chip resistor in which an excellent effect of obtaining inexpensive in cost.

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

  FIG. 1 is a cross-sectional view of a thin film chip resistor according to an embodiment of the present invention, and FIG. 2 is a flowchart showing a method for manufacturing the thin film chip resistor.

  In FIG. 1, 11 is an insulating substrate made of alumina of 96% purity, 12 is a pair of upper surface electrodes formed at both ends of the upper surface of the insulating substrate 11, and 13 covers at least a part of the upper surface electrode 12, and this upper surface. A thin film resistor electrically connected to the electrode 12, 14 is an inorganic protective film formed so as to cover the thin film resistor 13, and 15 is a pair of re-covers formed so as to cover the upper surface electrode 12 and the inorganic protective film 14. An upper surface electrode, 17 is an organic protective film formed so as to cover a part of the inorganic protective film 14 and the re-upper surface electrode 15, 18 is a pair of back surface electrodes formed at both ends of the back surface of the insulating substrate 11, and 20 is an upper surface. A pair of end face electrodes electrically connected to the electrode 12, the resurface upper electrode 15 and the back face electrode 18, 21 is a nickel plating layer covering the surfaces of the retop face electrode 15, the back face electrode 18 and the end face electrode 20, 22 is nickel plating 21 is a tin-plated layer covering the surface of the.

  Next, the manufacturing method of the thin film chip resistor in one embodiment of the present invention is shown in the flowchart of FIG. 2, FIGS. 3 (a) to 3 (c), FIGS. 4 (a) to (c), and FIG. A description will be given based on (d) and the manufacturing process diagrams of FIGS.

  First, as shown in FIG. 3A, a metal organic material mainly composed of gold is formed on the upper surface of a sheet-like insulating substrate 11c made of alumina having a purity of 96% and having primary division grooves 11a and secondary division grooves 11b. The paste is screen-printed so as to straddle the primary dividing grooves 11a and dried. Thereafter, in order to remove only the organic component of the metal organic paste and burn only the metal component on the insulating substrate 11c, a belt-type continuous firing furnace is used. Baking is performed at 600 ° C. to 900 ° C. to form a plurality of upper surface electrodes 12 (upper surface electrode forming step in FIG. 2).

  Next, as shown in FIG. 3 (b), a metal mask (not shown) made of 42 alloy is placed on the upper surface of the sheet-like insulating substrate 11c, and a nickel-chromium alloy or the like is used using a mask sputtering method. The plurality of thin film resistors 13 are formed so as to cover at least a part of the plurality of upper surface electrodes 12 and to be electrically connected to the plurality of upper surface electrodes 12. The material constituting the thin film resistor 13 is not limited to a nickel-chromium alloy, and other materials such as tantalum nitride, chromium silicon, and tantalum oxide can be used depending on required characteristics. A metal alloy that can be used as a body or a composite thereof may be used (thin film resistor forming step in FIG. 2).

Next, as shown in FIG. 3 (c), without removing the metal mask (not shown) used to form the thin film resistor 13, the mask sputtering method is used to perform high insulation such as silicon oxide or alumina. An inorganic protective film 14 made of a conductive material is formed to a thickness of 50 nm to 10 μm so as to cover the thin film resistor 13. In this case, a metal mask is placed on the upper surface of the sheet-like insulating substrate 11c and the thin film resistor 13 is formed by mask sputtering, and then the inorganic protective film 14 is formed by mask sputtering without removing the metal mask. Therefore, the formation of the thin film resistor 13 and the formation of the inorganic protective film 14 can be continuously performed by mask sputtering, thereby simplifying the manufacturing process of the thin film chip resistor and reducing the manufacturing cost. Is. Further, since the metal mask is composed of 42 alloy having a smaller thermal expansion coefficient than stainless steel, the metal mask can be used even when the metal mask is repeatedly used for forming the thin film resistor 13 and the inorganic protective film 14. As a result, the metal mask is not deformed due to heat history, and the metal mask is not easily displaced. Therefore, the formation position of the thin film resistor 13 is not shifted. Since the electrical connection with the body 13 is also reliably ensured, a thin film chip resistor excellent in reliability can be obtained at low cost. Further, as described above, this metal mask is made of 42 alloy (iron nickel-based alloy containing 42% nickel), and the thermal expansion coefficient of this 42 alloy is 4.5 to 6.5 × 10 ^−6. Since the thermal expansion coefficient is less than 10.4 × 10 ⁻⁶ / ° C. of stainless steel (SUS430) conventionally used as a metal mask material at / ° C., the above-described effects are remarkably exhibited. Further, if the thickness of the inorganic protective film 14 is less than 50 nm, the inorganic protective film 14 does not play a role as a protective film. On the other hand, if the thickness is thicker than 10 μm, the internal stress of the material of the inorganic protective film 14 increases. The inorganic protective film 14 is easily peeled off, cracked and chipped, and can no longer serve as a protective film. Therefore, the thickness of the inorganic protective film 14 is preferably 50 nm or more and 10 μm or less (inorganic protective film forming step in FIG. 2).

  Next, as shown in FIG. 4A, the upper surface electrode 15 is formed so as to have a thickness of 3 μm or more and 20 μm or less so as to cover a part of the upper surface electrode 12 and the inorganic protective film 14. The resurface electrode 15 is formed by printing and curing a conductive resin paste made of a mixture of epoxy-based resin and conductive particles such as silver, and the glass frit and the conductive particles are formed. Compared to a mixed and fired electrode material, it does not contain lead and is therefore excellent from the viewpoint of environmental protection. In addition, when compared with metal organic pastes such as gold resinates that are fired at 600 ° C. to 900 ° C., it can be cured at a relatively low temperature of 150 ° C. to 300 ° C., so the power consumption of the heat treatment furnace during production is small. In addition, since an inexpensive material that does not contain gold can be used, the manufacturing cost can also be reduced (re-top electrode formation process in FIG. 2).

  Next, as shown in FIG. 4B, the inorganic protective film 14 and the thin film resistor 13 (not shown) are cut using a laser to form a trimming groove 16, and the resistance value is set to a desired value. adjust. Since the trimming groove 16 for adjusting the resistance value is formed by cutting the inorganic protective film 14 and the thin film resistor 13 (not shown) using a laser after forming the upper surface electrode 15 again, the thin film chip is formed. The completed resistance value of the resistor does not fluctuate due to the effect of the resistance value of the re-upper surface electrode 15 made of a conductive resin, and the resistance value accuracy is extremely excellent within ± 0.1%. A thin film chip resistor is obtained. Here, it is necessary that the thickness of the re-upper surface electrode 15 that contacts the probe for measuring the resistance value during laser trimming be 3 μm or more and 20 μm or less. This is because, when the thickness of the upper surface electrode 15 is less than 3 μm, the contact resistance between the probe and the upper surface electrode 15 is large and the measurement of the resistance value is not stable, whereas the thickness of the upper surface electrode 15 is larger than 20 μm. In this case, since the resistance value in the thickness direction of the upper surface electrode 15 is increased, the resistance value accuracy of the final product of the thin film chip resistor is not stabilized due to the fluctuation of the resistance value. After the laser trimming process for forming the trimming groove 16, the sheet-like insulating substrate 11c is washed with a water-based or alcohol-based cleaning liquid as necessary to remove wrinkles generated in the laser trimming process. A cleaning step may be provided (trimming groove forming step in FIG. 2).

  Next, as shown in FIG.4 (c), the several organic protective film 17 is formed by printing and hardening a thermosetting resin paste so that the inorganic protective film 14 may be covered. The organic protective film 17 is printed with a mark for displaying characteristics such as a resistance value and a recognition mark used for determining the direction of the thin film chip resistor as necessary. Here, the organic protective film 17 shown in FIG. 4C is formed in a strip shape so as to be substantially parallel to the primary dividing groove 11 a, but the organic protective film 17 is the upper surface electrode 15 of the inorganic protective film 14. Each of the individual regions surrounded by the primary dividing groove 11a and the secondary dividing groove 11b may be formed independently so as to cover at least the region sandwiched between the two. In addition, this organic protective film 17 can reduce manufacturing cost by hardening simultaneously with the back surface electrode mentioned later. Further, it is preferable that the organic protective film 17 has a dimension that overlaps with the upper surface electrode 15 of 200 μm or less. This is because when the dimension of the organic protective film 17 that overlaps with the upper surface electrode 15 exceeds 200 μm, the portion of the organic protective film 17 and the upper surface electrode 15 that overlaps does not have a nickel plating layer that will be described later. In the portion where 17 and the upper surface electrode 15 overlap, the resistance value of the upper surface electrode 15 is added in series with the completed resistance value of the thin film chip resistor, thereby guaranteeing the accuracy of the completed resistance value of the thin film chip resistor. This is because it becomes difficult (the organic protective film forming step in FIG. 2).

  The steps of forming the upper surface electrode 12, the thin film resistor 13, the inorganic protective film 14, the re-upper surface electrode 15, the trimming groove 16, and the organic protective film 17 on the upper surface of the sheet-like insulating substrate 11c described so far are all sheet-like. In the state where nothing is formed on the back surface of the insulating substrate 11c, that is, the back surface of the sheet-like insulating substrate 11c is formed flat, for example, printing for forming the upper surface electrode 12 and the re-upper surface electrode 15 In the process, since the adsorption to the stage for fixing the sheet-like insulating substrate 11c is performed in a more stable state, the substrate is less likely to be cracked, and defects such as a substrate crack can be reduced. Product yield is improved. Further, in the mask sputtering process for forming the thin film resistor 13 and the inorganic protective film 14, the adsorption to the stage for fixing the sheet-like insulating substrate 11c becomes more stable, so that the parallelism of the substrate is improved. Thereby, the dimensional accuracy of the pattern of the thin film resistor 13 and the inorganic protective film 14 is improved, and the yield of the product is improved.

  Next, as shown in FIG. 5A, the upper surface electrode 12, the thin film resistor 13, the inorganic protective film 14, the re-upper surface electrode 15, the trimming groove 16, and the organic protective film 17 are formed on the upper surface of the sheet-like insulating substrate 11c. After the formation, the back electrode 18 is formed on the back surface of the sheet-like insulating substrate 11c. The back electrode 18 is formed, for example, by printing and curing a conductive resin paste made of a mixture of epoxy resin and conductive particles such as silver and does not contain lead. It is excellent from the viewpoint and can be cured at a relatively low temperature of 150 ° C. to 300 ° C., so that the manufacturing cost can be reduced. As shown in FIG. 5B, when the back electrode 18 is formed, a portion where the back electrode 18 is not printed at a location corresponding to the primary division groove 11a (not shown) of the sheet-like insulating substrate 11c. That is, the window portion 19 may be provided. Due to the presence of the window portion 19, the back electrode 18 has burrs even in the dividing step described later, that is, in the step of dividing the sheet-like insulating substrate 11 c into strips along the primary dividing groove 11 a (not shown). It becomes difficult to generate | occur | produce and a shape defect can be reduced by this. Further, as shown in FIG. 5C, by forming the back electrode 18 in an independent pattern on the back surface of the sheet-like insulating substrate 11c so as not to straddle the secondary division grooves 11b, the secondary division property is obtained. May be improved (rear electrode forming step in FIG. 2).

  Next, as shown in FIG. 5D, a sheet-like insulating substrate 11c is divided along the primary dividing groove 11a, thereby obtaining a strip-like substrate 11d as shown in FIG. Step of dividing into strips of FIG. 2).

  Next, as shown in FIG. 6B, the strip-shaped substrate 11d is electrically connected to the upper surface electrode 12 (not shown), the re-upper surface electrode 15 and the back surface electrode 18 (not shown). The end face electrodes 20 are formed on the both end faces. The end face electrode 20 is formed by applying and curing a conductive resin paste made of a mixture of epoxy resin or the like and conductive particles such as silver, and does not contain lead. In view of the above, it can be manufactured at a lower cost compared with the case where the end face electrode 20 is formed of a thin film such as a sputter (end face electrode forming step in FIG. 2).

  Next, as shown in FIG. 6C, the strip-shaped substrate 11d is divided along the secondary dividing line 11b to obtain a piece-like substrate 11e (step of dividing into pieces shown in FIG. 2). .

  Finally, as shown in FIG. 6 (d), in order to ensure reliability during soldering, a nickel plating layer 21 (not shown) is formed on the exposed electrode portions of the upper surface, the back surface, and the end surface of the individual substrate 11e. The thin film chip resistor in one embodiment of the present invention is manufactured by forming a tin plating layer 22 so as to cover this nickel plating layer (not shown). If a low resistivity material such as copper or a copper-based alloy is plated before the nickel plating layer 21 is formed, the resistance value of the plated portion can be lowered. It is possible to further improve the accuracy of the completed resistance value (plating layer forming step in FIG. 2).

  Here, the results of manufacturing 1608 size and 1005 size thin film chip resistors in the conventional thin film chip resistor manufacturing method and the thin film chip resistor manufacturing method in one embodiment of the present invention are shown in Table 1. Show.

As apparent from Table 1, in the conventional method of manufacturing a thin film chip resistor, SUS430, which is stainless steel, is used as the material of the metal mask used for forming the thin film resistor 13 and the inorganic protective film 14. However, since the thermal expansion coefficient of SUS430 is as large as 10.4 × 10 ⁻⁶ / ° C., when the metal mask made of SUS430 is repeatedly used for forming the thin film resistor 13 and the inorganic protective film 14, The metal mask is deformed in response to the thermal history, and as a result, the displacement of the metal mask is likely to occur, and the formation position of the thin film resistor 13 is also likely to be displaced. In some cases, the electrical connection with the body 13 may not be guaranteed, and particularly in the case of a small-sized thin film chip resistor, the product yield tends to deteriorate significantly. It was.

On the other hand, in the method of manufacturing a thin film chip resistor in one embodiment of the present invention, 42 alloy is used as the material of the metal mask used for forming the thin film resistor 13 and the inorganic protective film 14. Since the thermal expansion coefficient of 42 alloy is as small as 4.5 to 6.5 × 10 ⁻⁶ / ° C., a metal mask composed of 42 alloy is repeatedly used for forming the thin film resistor 13 and the inorganic protective film 14. However, the metal mask is not deformed in response to the thermal history, and as a result, the displacement of the metal mask is less likely to occur, so that the formation position of the thin film resistor 13 is not shifted. The electrical connection between the electrode 12 and the thin film resistor 13 is reliably ensured, and in particular, the tendency to improve the product yield is prominent in a small-sized thin film chip resistor. , Thin film chip resistor which is excellent in reliability in which an effect that is obtained inexpensively in cost.

  In the above-described embodiment of the present invention, the method of manufacturing using the sheet-like insulating substrate 11c in which the primary divided grooves 11a and the secondary divided grooves 11b are provided on the upper surface in advance has been described. It is not limited to the above, and a functional element may be formed on the upper and rear surfaces of a non-slit substrate that does not have division grooves in advance, and then the substrate may be cut using a dicing method to obtain a desired shape. is there.

  In the above-described embodiment of the present invention, the configuration in which one thin film resistor is provided with one thin film resistor 13 is not limited to this configuration. The present invention can also be applied to a multiple or network type configuration having a plurality of thin film resistors 13 in a chip resistor.

  The method of manufacturing a thin film chip resistor according to the present invention comprises a metal mask for forming a thin film resistor made of 42 alloy having a small coefficient of thermal expansion, thereby preventing the displacement of the formation position of the thin film resistor and the upper surface electrode. The electrical connection with the thin film resistor is surely ensured, and is particularly useful in the method of manufacturing the thin film chip resistor.

Sectional drawing of the thin film chip resistor in one embodiment of this invention Flow chart showing the manufacturing method of the thin film chip resistor (A)-(c) Manufacturing process figure which shows the manufacturing method of the thin film chip resistor (A)-(c) Manufacturing process figure which shows the manufacturing method of the thin film chip resistor (A)-(d) Manufacturing process figure which shows the manufacturing method of the thin film chip resistor (A)-(d) Manufacturing process figure which shows the manufacturing method of the thin film chip resistor Cross-sectional view of a conventional thin film chip resistor Flow chart showing the manufacturing method of the thin film chip resistor

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Insulation board | substrate 11c Sheet-like insulation board | substrate 11d Strip-shaped board | substrate 11e Single piece board | substrate 12 Upper surface electrode 13 Thin film resistor 14 Inorganic protective film 15 Re-upper surface electrode 16 Trimming groove 17 Organic protective film 18 Back surface electrode 20 End surface electrode

Claims (1)

Forming a plurality of upper surface electrodes by printing and baking an organic metal paste on the upper surface of the sheet-like insulating substrate; covering at least a part of the plurality of upper surface electrodes; Forming a plurality of thin film resistors so as to be connected to each other, forming a plurality of inorganic protective films so as to cover the plurality of thin film resistors, and a conductive resin so as to cover the plurality of upper surface electrodes A step of forming a plurality of resurface electrodes by printing and curing the paste, and a plurality of organic protective films by printing and curing a thermosetting resin paste so as to cover the plurality of inorganic protective films A step of forming a plurality of backside electrodes by printing and curing a conductive resin paste on the backside of the sheet-like insulating substrate, and dividing the sheet-like insulating substrate into strips And an end face electrode by applying and curing a conductive resin paste on the end face of the strip-like board so as to be electrically connected to the upper face electrode, the upper face electrode, and the rear face electrode. And forming a thin film resistor by mask sputtering on the upper surface of the sheet-like insulating substrate to form the thin film resistor, and then continuing without removing the metal mask. A method of manufacturing a thin film chip resistor in which an inorganic protective film is formed by mask sputtering.

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