JP5262159B2 - Method for manufacturing thin film chip resistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method manufacturing a thin film chip resistor of a highly accurate resistance value with a small number of processes and a reduced cost. <P>SOLUTION: The thin chip resistor manufacturing method includes the processes of: forming a thin film upper surface electrode 12 on an upper surface of an insulating substrate 11; forming a conductor by a thin film process almost on the entire surface of the insulating substrate 11; forming a resistor pattern by a photo-lithographic process to form a thin film resistor 13; and forming a conductor resin upper surface electrode 15 to cover a part of the thin film resistor 13 superposed on the thin film upper surface electrode 12. A plurality of holes 14 are formed in the part of the thin film resistor 13 superposed on the thin film upper surface electrode 12 to expose the thin film upper surface electrode 12 and the thin film upper surface electrode 12 is electrically connected to the conductor resin upper surface electrode 15 via the plurality of holes 14. <P>COPYRIGHT: (C)2009,JPO&amp;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. 4, 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 first upper surface electrodes 3 formed on the substrate, and a nickel chromium alloy formed by sputtering so as to be electrically connected to the pair of first upper surface electrodes 3 and then patterned into a desired shape using a photolithography method, etc. A resistor 4 comprising a protective film 5, a protective film 5 (first protective film 5 a, second protective film 5 b, third protective film 5 c) covering the part of the resistor 4, the upper surface electrode 3, and the resistor 4 and a pair of second upper surface electrodes 6 made of silver-based resin formed on both ends of the upper surface of the insulating substrate 1 so as to be in contact with the protective film 5, and the second upper surface electrodes 6 And the back electrode 2 are electrically connected. A pair of end surface electrodes 7 formed on both ends of the insulating substrate 1, a nickel plating layer 8 formed on the exposed portions of the end surface electrode 7, the second upper surface electrode 6 and the back electrode 2, and the nickel plating. The tin plating layer 9 covering the layer 8 was provided.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known. In the conventional thin film chip resistor described therein, only the resistor 4 is formed of a thin film, and The main constituent elements other than those, ie, the back electrode 2, the first top electrode 3, the second top electrode 6 and the end electrode 7 are all formed by a thick film process such as screen printing using a conductive paste, Compared with the case where main components (electrodes, etc.) other than the body are formed as thin films, the first upper surface electrode 3 and the second upper surface electrode 6 can be manufactured at low cost through the through holes formed in the resistor 4. By sandwiching the resistor 4, the adhesion between the thin film resistor 4 and the first upper surface electrode 3 and the second upper surface electrode 6 made of a thick film can be improved.
JP 2002-640002 A

  However, in the conventional method for manufacturing a thin film chip resistor described in Patent Document 1, a through-hole provided in the resistor 4 in order to bring the first upper surface electrode 3 and the second upper surface electrode 6 into close contact with each other, Since the resistor 4 is formed at the same time when the photolithographic method is used, the first upper surface electrode 3 is positioned on the first upper surface electrode 3 when a material that is difficult to oxidize, such as gold, is used. When a part of the resistor 4 is removed by etching, a local cell reaction proceeds between the first upper surface electrode 3 that is a noble metal and the resistor 4 that is a base metal, and is positioned on the first upper surface electrode 3. Since the resistor 4 is over-etched and affects the portion of the resistor pattern in the vicinity of the first upper surface electrode 3, the desired thin film resistor pattern shape cannot be obtained, and a defect occurs at the initial resistance value stage. I can't make things later It was. On the other hand, when the etching amount is conserved so as not to cause a defect due to overetching, the through hole is not sufficiently formed in the resistor 4 and the first upper surface electrode 3 is not exposed, and therefore exists on the surface of the resistor 4. Due to the influence of the very thin oxide film, electrical contact between the second upper surface electrode 6 and the first upper surface electrode 3 cannot be obtained, and the probe is brought into contact with the second upper surface electrode 6 to accurately correct the resistance value. When performing (trimming), an error occurs between the measurement of the resistance value at the time of trimming and the measurement of the resistance value at the inspection of the finished product, and a high-precision resistor having a resistance tolerance of ± 0.1% or less When manufacturing a vessel, the yield deteriorated. Although a method of simultaneously forming the pattern of the resistor 4 and the through hole by a mask sputtering method is also conceivable, the thickness of the metal mask used in the mask sputtering method is usually 50 to 300 μm, and the metal mask having such a thickness In the mask sputtering method using, it was difficult to form a resistor pattern having a line width of 10 to 20 μm and having both a ladder area and a fine adjustment area. Further, after forming a thin film as a resistor material by a mask sputtering method so that an exposed portion of the first upper surface electrode 3 provided for direct contact between the first upper surface electrode 3 and the second upper surface electrode 6 appears, a photolithographic method is used. However, a method of separately forming a resistor pattern and a method of separately performing a photolithographic method in the step of forming the exposed portion of the first upper surface electrode 3 and the step of forming the resistor pattern are also conceivable. This resulted in increased costs and decreased accuracy, such as increased variations in temperature characteristics.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to provide a method of manufacturing a thin film chip resistor that can manufacture a thin film chip resistor having a high resistance value accuracy at a low cost with a small number of steps. is there.

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

According to a first aspect of the present invention, a plurality of thin film upper surface electrodes made of a noble metal are formed on the upper surface of a sheet-like insulating substrate, and a conductor is formed on almost the entire surface of the sheet-like insulating substrate by a thin film process. Then, a plurality of thin film resistors are formed by forming a resistor pattern by a photolithography process, and a plurality of conductive resin pastes are printed so as to cover a portion of the thin film resistor that overlaps the thin film upper surface electrode. A step of forming a conductive resin upper surface electrode and a step of adjusting a resistance value by applying laser trimming to the resistor pattern, and a plurality of holes are formed by a laser in a portion overlapping the thin film upper surface electrode in the thin film resistor. The thin film upper surface electrode is exposed, and the thin film upper surface electrode and the conductive resin upper surface electrode are electrically connected through the plurality of holes. According to this manufacturing method, a plurality of holes are provided by a laser in a portion overlapping the thin film upper surface electrode in the thin film resistor to expose the thin film upper surface electrode, and the plurality of holes Since the thin film upper surface electrode and the conductive resin upper surface electrode are electrically connected via a thin film resistor patterning using a photolithographic method as in the prior art, a through hole is formed at the same time. By using a laser, a hole of a desired size can be quickly and reliably formed at a desired position as compared with the one made to do so, and through a plurality of holes provided by the laser Since the upper surface electrode of the conductor resin that contacts the trimming probe and the upper surface electrode of the thin film made of a noble metal that is difficult to oxidize are in direct contact with each other, the resistance value is measured by the thin film resistor. It is not affected by the oxide film existing on the surface, and this eliminates the error between the resistance value at the time of trimming and the completed resistance value. It has the effect that it is.

  As described above, the method for manufacturing a thin film chip resistor according to the present invention provides a plurality of holes by a laser in a portion overlapping the thin film upper surface electrode in the thin film resistor to expose the thin film upper surface electrode, and through the plurality of holes. Since the thin film upper surface electrode and the conductive resin upper surface electrode are electrically connected to each other, the thin film resistor is patterned using the photolithographic method as in the conventional method, and at the same time, the through hole is formed. Compared to the above, by using a laser, a hole of a desired size can be formed quickly and surely at a desired position, and the surface of the conductive resin top electrode that contacts the trimming probe and the surface are oxidized. The thin film upper surface electrode made of a difficult precious metal is in direct contact with the plurality of holes provided by the laser, so that the resistance value can be measured on the thin film resistor. Since there is no influence of the oxide film on the surface, there is almost no error between the resistance value at the time of trimming and the completed resistance value, and this makes it possible to obtain a thin film chip resistor with high resistance accuracy at low cost with less man-hours. This is an excellent effect.

  Hereinafter, a method for manufacturing a thin film chip resistor in 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. In FIG. 1, 11 is an insulating substrate made of alumina with a purity of 96%, 12 is a pair of thin film upper surface electrodes formed on both ends of the upper surface of the insulating substrate 11, 13 covers at least a part of the thin film upper surface electrode 12, The thin film resistor is electrically connected to the thin film upper surface electrode 12, and the thin film resistor 13 is provided with a hole 14 so that the thin film upper surface electrode 12 is exposed. 15 is a pair of conductor resin upper surface electrodes formed so as to cover the thin film upper surface electrode 12 and the hole 14, 16 is a protective film formed so as to cover all of the thin film resistor 13 and a part of the conductor resin upper surface electrode 15, Reference numeral 17 denotes a pair of back electrodes formed on both ends of the back surface of the insulating substrate 11, reference numeral 18 denotes a pair of end face electrodes electrically connected to the thin film top electrode 12, conductor resin top electrode 15 and back electrode 17, and 19 denotes a conductor. A nickel plating layer that covers the surfaces of the resin upper surface electrode 15, the back surface electrode 17, and the end surface electrode 18, and 20 is a tin plating layer that covers the surface of the nickel plating layer 19.

  Next, the manufacturing method of the thin film chip resistor in one embodiment of the present invention is based on the cross-sectional view of FIG. 1 and the manufacturing process diagrams of FIGS. 2 (a) to 2 (d) and FIGS. 3 (a) to 3 (d). I will explain.

  First, as shown in FIG. 2 (a), a noble metal material that hardly oxidizes in the air, for example, a metal organic paste mainly composed of gold, is screened on both ends of the upper surface of the insulating substrate 11 made of 96% purity alumina. After printing and drying, in order to remove only the organic component of the metal organic paste, and to burn only the metal component onto the insulating substrate 11, it is fired at 600 to 900 ° C. in a belt-type continuous firing furnace, and the thin film upper surface electrode 12 Form. Here, FIG. 2A shows a rectangular insulating substrate 11 having a long side L (mm) and a short side W (mm), which is the individual size of the thin film chip resistor. In the description of the process, the individual-sized insulating substrate 11 is used for explanation, but in an actual manufacturing process, a sheet-shaped insulating substrate capable of obtaining a large number of the individual-sized insulating substrates 11 vertically and horizontally is used. The sheet-like insulating substrate is divided into strips or individual pieces before the end face electrode forming step described later. The material constituting the thin film upper surface electrode 12 is not limited to a gold-based material, and other noble metal materials that are difficult to oxidize in air, such as silver, platinum, iridium, and alloys thereof may be used. Is.

  Next, as shown in FIG. 2B, a thin film conductor made of a nickel chromium alloy or the like is formed on almost the entire surface of the insulating substrate 11 using a thin film process such as sputtering, and then the thin film conductor is not required using a photolithography process. The thin film resistor 13 is formed by forming the resistor pattern from which the portion is removed. Here, the pattern of the thin film resistor 13 shown in FIG. 2B has a thin line width of 10 to 20 μm and a complicated shape having both a ladder area (coarse adjustment area) and a fine adjustment area. Therefore, the pattern of the thin film resistor 13 must be formed using a photolithography process. 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.

  Next, as shown in FIG. 2C, the surface of the thin film upper surface electrode 12 is exposed by providing a plurality of holes 14 by applying a laser to a portion of the thin film resistor 13 that overlaps the thin film upper surface electrode 12. Here, by applying a laser whose beam diameter and output are controlled to the thin film resistor 13, a hole 14 having a desired size can be quickly and reliably formed at a desired position. The electrical contact between the thin film upper surface electrode 12 and the thin film upper surface electrode 12 is also improved. In the cross-sectional view of FIG. 1, the hole 14 is formed so as to remove a part of the thin film upper surface electrode 12 in the thickness direction, but the hole 14 removes all of the thin film upper surface electrode 12 in the thickness direction. Thus, it may be formed so as to reach a part of the insulating substrate 11. In this case, an electrical contact between the conductor resin upper surface electrode and the thin film upper surface electrode 12 described later is ensured through the side surface of the hole 14.

  Next, as shown in FIG. 2D, the conductor resin upper surface electrode 15 is 3 μm or more and 20 μm or less so as to cover the hole 14 and be electrically connected to the thin film upper surface electrode 12. Form. The conductor resin upper surface 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 conductive particles. Compared with the electrode material obtained by mixing and firing, it is excellent from the viewpoint of environmental protection because it does not contain lead and the temperature of the manufacturing process can be lowered.

  Next, as shown in FIG. 3A, the resistance value of the thin film resistor 13 is adjusted by performing laser trimming on the thin film resistor 13. Here, when performing laser trimming, the probe for resistance measurement is arranged on the conductor resin upper surface electrode 15, and therefore, the conductor resin upper surface electrode 15 and the thin film upper surface electrode 12 in contact with the probe are in direct contact with each other. The resistance value is hardly affected by the oxide film existing on the surface of the thin film resistor 13, so that there is almost no error between the resistance value at the time of trimming and the completed resistance value. High-precision products of 0.1% or less can be produced quickly and reliably. Before the thin film resistor 13 is subjected to laser trimming, an inorganic protective film (not shown) made of a highly insulating material such as silicon oxide or alumina is covered with the mask sputtering method so as to cover the thin film resistor 13. Further, it may be formed with a thickness of 50 nm to 10 μm.

  In addition, it is appropriate that the thickness of the conductor resin 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 conductor resin upper surface electrode 15 is less than 3 μm, the contact between the probe and the conductor resin upper surface electrode 15 becomes unstable because the probe damages or penetrates the inside of the conductor resin upper surface electrode 15. On the other hand, when the thickness of the conductor resin upper surface electrode 15 is larger than 20 μm, the resistance value in the thickness direction of the conductor resin upper surface electrode 15 is increased, and the resistance value fluctuates accordingly. Thus, the resistance measurement accuracy of the thin film chip resistor becomes unstable. In addition, after the laser trimming process is finished, a cleaning process may be provided to remove wrinkles generated in the laser trimming process by ultrasonically cleaning the insulating substrate 11 using an aqueous or alcohol-based cleaning liquid as necessary. It ’s good.

  Next, as shown in FIG. 3B, a protective film 16 is formed by printing and curing a thermosetting resin paste so as to cover all of the thin film resistor 13 and a part of the conductor resin upper surface electrode 15. To do. The protective film 16 is printed with a marking 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. The protective film 16 preferably has a dimension overlapping with the conductive resin upper surface electrode 15 of 200 μm or less. This is because if the dimension of the protective film 16 that overlaps the conductor resin upper surface electrode 15 exceeds 200 μm, a nickel plating layer and a tin plating layer, which will be described later, are not attached to the portion where the protective film 16 and the conductor resin upper surface electrode 15 overlap. The resistance value of the conductive resin upper surface electrode 15 is added in series to the completed resistance value of the thin film chip resistor at the portion where the protective film 16 and the conductive resin upper surface electrode 15 overlap, and the thin film chip resistance particularly at a low resistance value. This is because it is difficult to guarantee the accuracy of the complete resistance value of the vessel and the accuracy of the TCR.

  Next, as shown in FIG. 1 and FIG. 3C, after the back electrode 17 is formed on the back surface of the insulating substrate 11, it is electrically connected to the thin film top electrode 12, the conductor resin top electrode 15 and the back electrode 17, respectively. Thus, the end face electrodes 18 are formed on both end faces of the insulating substrate 11. This end face electrode 18 is formed, for example, by applying and curing a conductive resin paste made of a mixture of epoxy-based resin and conductive particles such as silver, nickel, and carbon. In this case, lead Therefore, it is excellent from the viewpoint of environmental protection, and can be manufactured at a lower cost than the case where the end face electrode 18 is formed of a thin film such as sputtering.

  Finally, as shown in FIGS. 1 and 3 (d), in order to ensure reliability during soldering, a nickel plating layer 19 is formed on the exposed electrode portions of the top surface, back surface, and end surface of the insulating substrate 11. Further, by forming the tin plating layer 20 so as to cover the nickel plating layer 19, the thin film chip resistor in one embodiment of the present invention is manufactured. If a low resistivity material such as copper or a copper-based alloy is plated before the nickel plating layer 19 is formed, the resistance value of the plated portion can be lowered. It is possible to further increase the accuracy of the completed resistance value.

  As is apparent from the above description, in the method of manufacturing a thin film chip resistor in one embodiment of the present invention, a plurality of holes 14 are provided by a laser in a portion overlapping the thin film upper surface electrode 12 in the thin film resistor 13. Since the thin film upper surface electrode 12 is exposed and the thin film upper surface electrode 12 and the conductive resin upper surface electrode 15 are electrically connected through the plurality of holes 14, the conductive resin upper surface electrode 15 in contact with the trimming probe. The thin film upper surface electrode 12 made of a noble metal whose surface is difficult to oxidize is in direct contact with the plurality of holes 14 provided by the laser, whereby the resistance value is measured on the surface of the thin film resistor 13. Therefore, there is almost no error between the resistance value during trimming and the completed resistance value. Accordingly, it is intended to be produced inexpensively with high resistance precision thin film chip resistor is small steps.

  In the above-described embodiment of the present invention, the configuration in which one thin film chip resistor has a pair of thin film upper surface electrodes 12 and one thin film resistor 13 has been described. However, the present invention is limited to this configuration. Instead, the present invention can also be applied to a multiple or network type configuration having a plurality of pairs of thin film upper surface electrodes 12 and a plurality of thin film resistors 13 in one thin film chip resistor.

  In the method of manufacturing a thin film chip resistor according to the present invention, a plurality of holes are provided by a laser in a portion overlapping with a thin film upper surface electrode in the thin film resistor, and the thin film upper surface electrode and the conductive resin upper surface electrode are provided via the plurality of holes. By being configured to be electrically connected, the error between the resistance value at the time of trimming and the completed resistance value is reduced. Particularly, the resistance value accuracy is ± 0.1% or less. It is useful in the manufacturing method of a thin film chip resistor.

Sectional drawing of the thin film chip resistor in one embodiment of this invention (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

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Insulation board | substrate 12 Thin film upper surface electrode 13 Thin film resistor 14 Hole 15 Conductor resin upper surface electrode

Claims (1)

Forming a plurality of thin film upper surface electrodes made of noble metal on the upper surface of a sheet-like insulating substrate, and forming a resistor pattern by a photolithography process after forming a conductor on a substantially entire surface of the sheet-like insulating substrate by a thin film process Forming a plurality of thin film resistors, forming a plurality of conductive resin upper surface electrodes by printing a conductive resin paste so as to cover a portion of the thin film resistor overlapping the thin film upper surface electrode, and the resistance A step of adjusting a resistance value by performing laser trimming on a body pattern, a plurality of holes are provided by a laser in a portion overlapping the thin film upper surface electrode in the thin film resistor, and the thin film upper surface electrode is exposed. A thin film chip configured to electrically connect the thin film upper surface electrode and the conductive resin upper surface electrode through a plurality of holes. Method of manufacturing a resistor.

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