JP2011009288A - Substrate built-in chip resistor and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate built-in chip resistor that makes a thick-film chip resistor small in thickness and is free of large warpage of a large-sized substrate, and to provide a method of manufacturing the same.SOLUTION: The substrate built-in chip resistor includes: an insulating substrate 11 of ≤10 μm in thickness which has a top and a reverse surface; a pair of internal electrodes 12a and 12b formed on the top surface of the substrate and made of thick-film sintered bodies; a resistance film 13 made of a thick-film sintered body, formed between the pair of internal electrodes; and a glass or metal layer 16 formed on the reverse surface of the substrate 11 and made of a thick-film sintered body. The resistance film 13 is coated with protective films 17 and 18, second internal electrodes 19a and 19b are formed of conductive resin films on parts of the protective films and the internal electrodes 12a and 12b, and a plating layer is formed on a top surface of the second internal electrode.

Description

  The present invention relates to a thick film chip resistor, and more particularly to a substrate built-in chip resistor having a very thin thickness for use in a circuit board and a method for manufacturing the same.

  As electronic devices become lighter, thinner and smaller, electronic components such as chip resistors are not mounted on the surface of the circuit board, but may be mounted on the inner layer of a laminated circuit board, etc. An example has been proposed (see Patent Document 1). In such a chip resistor with a built-in substrate, the thickness is preferably as thin as possible, and it is preferable to dispose an electrode, a resistor, and a protective film on only one side from the viewpoint of thinning.

JP 2004-140285 A

  However, an insulating substrate such as alumina is indispensable for a chip resistor, and if this thickness is reduced, an electrode, a resistor, and a protective film are disposed only on one side of the substrate. There is a problem that warpage is likely to occur and defective products are likely to occur.

  The present invention has been made based on the above-described circumstances, and reduces the thickness of the thick film chip resistor and does not cause warping of a large substrate at the manufacturing stage, and a method of manufacturing the chip resistor. The purpose is to provide.

  The chip resistor for a substrate according to the present invention includes an insulating substrate having a surface and a back surface and a thickness of 100 μm or less, an internal electrode made of a pair of thick film fired bodies formed on the surface of the substrate, and the pair And a glass layer or a metal layer made of a thick film fired body formed on the back surface of the substrate.

  In addition, the method for manufacturing a chip resistor with a built-in substrate according to the present invention provides a large-sized insulating substrate having a surface and a back surface and a thickness of 100 μm or less, and fires a thick film on each section of the surface of the large-sized substrate. Forming an internal electrode made of a body, forming a glass layer or a metal layer made of a thick film fired body on the back surface of the large substrate, forming a resistance film made of a thick film fired body connected to the internal electrode, A protective film covering the resistance film is formed, a large substrate is divided into chip pieces for each section, and a plating layer is formed on the electrode surface of the chip pieces.

  According to the present invention, since a thick film fired body made of a glass layer is formed on the back surface of the insulating substrate, the thick film internal electrode, the thick film resistance film, and the thick film are formed only on the surface of the thin large substrate in the manufacturing stage. When forming a thick film fired body such as a glass protective film, the thermal expansion of the two is balanced, and warping of a large substrate can be prevented. Therefore, while using a large-sized substrate having a normal size (for example, 50 mm × 60 mm), it is possible to prevent the substrate from being cracked due to the warping of the substrate, and to manufacture a chip resistor with a built-in substrate with a high yield. be able to.

FIG. 2A is a cross-sectional view, FIG. 2B is a top view, and FIG. 3C is a bottom view of the chip resistor with a built-in substrate according to the first embodiment of the present invention. It is explanatory drawing which shows the example of the thickness of each part of the chip resistor. It is sectional drawing of the chip resistor for board | substrates of 2nd Embodiment of this invention, and its modification. It is sectional drawing which shows the manufacturing process of the chip resistor of 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the chip resistor of 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the chip resistor of the modification of 2nd Embodiment of this invention. It is explanatory drawing which shows the interior state to the multilayer circuit board of the chip resistor of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 7. In addition, in each figure, the same code | symbol is attached | subjected and demonstrated to the same or equivalent member or element.

As shown in FIGS. 1 and 2, the chip resistor according to the first embodiment of the present invention has a thickness of 10 μm on the surface of an insulating substrate 11 such as alumina having a surface and a back surface of about 100 μm. A pair of internal electrodes 12a and 12b made of a thick film fired body such as Ag—Pd is provided, and a resistance film 13 made of a thick film fired body such as RuO ₂ is disposed between the pair of electrodes. . The resistance film 13 is covered with a glass layer protective film 17 made of a thick film fired body and a protective film 18 made of an epoxy resin or the like. The internal electrodes 12a and 12b are covered with Ni plating layers 14a and 14b and Cu plating layers 15a and 15b having a thickness of about 7 μm, respectively.

  On the back surface of the substrate 11, a glass layer 16 made of, for example, a lead borosilicate thick film fired body having a thickness of about 10 μm is formed. The glass layer 16 serves as a reinforcing layer for increasing the mechanical strength because the substrate 11 is thin.

  The thickness of the entire resistor is 134 μm, and a thick film chip resistor that can be built in a circuit board having a thickness of 150 μm or less is obtained. The size of the resistor can be applied to normal chip resistor sizes such as 1005 type (1.0 mm × 0.5 mm) and 0603 type (0.6 mm × 0.3 mm). The thickness can be reduced to less than half the thickness of the resistor.

  FIG. 3 shows a substrate built-in chip resistor according to the second embodiment of the present invention and its modification. As shown in FIG. 3A, the chip resistor of the second embodiment is mainly composed of Ag connected to the internal electrodes 12a and 12b and having a larger area and overlapping the protective films 17 and 18. The second internal electrodes 19a and 19b made of the conductive resin are provided, and Ni plating layers 14a and 14b and Cu plating layers 15a and 15b are deposited on the electrodes.

  In the case of the chip resistor for a built-in substrate, there is a case where the external electrode is exposed by irradiating a laser beam after being built in the circuit board and connected to the external wiring, and the external electrode is preferably as large as possible. In this embodiment, after forming the protective films 17 and 18, second internal electrodes 19a and 19b made of a conductive resin mainly composed of Ag are formed so as to overlap the protective films 17 and 18, and a Ni plating layer is formed thereon. By forming 14a and 14b and Cu plating layers 15a and 15b, a chip resistor with a built-in substrate having an external electrode larger than the internal electrodes 12a and 12b can be produced.

  FIG. 3B shows a chip resistor of this modification. In this example, the internal electrodes 12a and 12b are arranged on the resistance film 13, and other configurations are the same as those in the embodiment of FIG. In this case, the resistance film end does not overlap the internal electrode end as shown in FIG. 3A, so that the height of the portion where the resistance film internal electrodes 12a, 12b and the protective films 17, 18 overlap is flattened. Thus, the height of the entire chip resistor can be reduced.

  FIG. 3 (c) shows a further modified chip resistor. In this example, the internal electrodes 12a and 12b are omitted and the second internal electrodes 19a and 19b are directly connected to the resistance film 13 in the embodiment shown in FIG. As a result, the height of the chip resistor can be further reduced.

  Next, the manufacturing process of the chip resistor of the present invention will be described. First, as shown in FIG. 4A, a large insulating substrate 21 made of ceramics such as alumina having a thickness of 100 μm or less and having a front surface and a back surface is prepared. This substrate 21 is provided with vertical and horizontal dividing grooves 21a, and can be divided into chip pieces for each section after device formation. The dividing groove 21a is formed by embossing or a laser processing machine.

  And as shown in FIG.4 (b), it forms from the thick film fired body by forming the internal electrode pattern ranging over each division of the surface of the board | substrate 21 by screen printing of Ag-Pd paste, and baking after drying. The internal electrode 22 is formed. On the back surface of the substrate 21, as an example, a lead borosilicate glass paste is screen-printed on the entire surface, dried and fired to form a glass layer 26 made of a thick film fired body.

  The firing of the internal electrode 22 and the firing of the glass layer 26 may be performed simultaneously. Thus, by forming a glass layer made of a thick film fired body on the back surface of the substrate 21, a thick film fired body is formed on the front and back surfaces of the thin substrate 21, and thermal expansion is balanced. 21 warpage can be suppressed.

Next, as shown in FIG. 4 (c), a thick film fired body is formed by forming a resistive film pattern straddling the inner electrodes 22 and 22 on both sides of one section by screen printing of RuO ₂ paste, and firing after drying. The resistance film 13 made of is formed in each section. Then, as shown in FIG. 4D, a glass protective film pattern that covers the resistive film 13 is formed by screen printing by screen printing of glass paste, and dried and baked to cover the resistive film 13. A glass protective film 17 made of a thick film fired body is formed.

  Next, as shown in FIG. 4E, laser trimming is appropriately performed to adjust the resistance value. A symbol T in the figure indicates a trimming mark. And as shown in FIG.4 (f), the resin protective film pattern which coat | covers the glass protective film 17 by screen printing of resin pastes, such as an epoxy resin, is formed by screen printing, and it heat-hardens, so that glass A resin protective film 18 that covers the protective film is formed.

  Next, the large-sized substrate 21 is divided into chip pieces of the substrate 11 by the primary break and the secondary break. At this time, the internal electrodes 22 of the large-sized substrate stage are connected to the internal electrodes 12a and 12b at both ends of the chip pieces. The glass layer which is divided and formed on the entire back surface is divided into glass layers 16 for each chip piece. The division may be performed by dicing or scribing.

  Then, Ni plating layers 14a and 14b and Cu plating layers 15a and 15b are formed by performing Ni plating and Cu plating on the surfaces of the internal electrodes 12a and 12b not covered with the protective films 17 and 18, respectively. FIG. 4F shows this stage, and at this stage, the manufacturing process of this chip resistor is completed.

  According to the above manufacturing process, since the thick film fired body made of the glass layer is formed on the back surface of the large substrate at the initial stage, the thick film internal electrode, the thick film resistance film, and the thick film are formed only on the surface of the thin large substrate. When forming a thick film fired body such as a glass protective film, the thermal expansion of the two is balanced, and warping of a large substrate can be prevented. Therefore, while using a large-sized substrate having a normal size (for example, 50 mm × 60 mm), it is possible to prevent the substrate from being cracked due to the warp of the substrate, which is conventionally generated, and to manufacture a chip resistor with a built-in substrate at a high yield. be able to.

  In addition, since this chip resistor includes a glass layer 16 that is a thick film fired body on the back surface of the thin ceramic insulating substrate 11, the glass layer 16 functions as a reinforcing material for the substrate 11, and breaks the substrate at the stage of use. Reinforcing effects can be demonstrated. The glass layer 16 may be a metal layer. In this case, for example, the same material as that of the internal electrode 22 is printed on the back surface of the substrate 11 by a method such as screen printing or spin coating, and baked. When the metal layer is used, in addition to the effect of reinforcing the substrate, the heat dissipation effect of the resistor is also improved. However, since a plating layer is formed on the metal layer in a later process, the thickness of the entire chip resistor is increased. For this reason, it is preferable to use a glass layer in terms of reducing the height.

  Next, a manufacturing process of the substrate built-in chip resistor of the second embodiment of the present invention shown in FIG. 3A will be described with reference to FIG. 5 (a)-(f), that is, a large substrate 21 provided with a dividing groove 21a is prepared, an internal electrode 22 is formed on the substrate surface, a glass layer 26 is formed on the substrate back surface, and the substrate surface The steps of forming the resistance film 13, the glass protective film 17, and the resin protective film 18 are the same as the steps of FIGS.

  In this chip resistor manufacturing process, after the resin protective film 18 is formed, a conductive resin paste containing Ag as a main component is screen-printed to form a second internal portion on the protective films 17 and 18 and the internal electrode 22. By forming an electrode pattern and heating and curing, the second internal electrode 19 made of a conductive resin mainly composed of Ag is formed. In the example shown in the figure, the second internal electrode 19 is formed so as not to cover the dividing groove 21a so as not to deteriorate the dividing property, but may be formed continuously.

  Then, the large-sized substrate 21 is divided into chip-piece substrates 11 by the primary break and the secondary break, and Ni plating and Cu plating are applied to the surfaces of the second internal electrodes 19a and 19b. , 14b and Cu plating layers 15a, 15b. At this stage, the chip resistor according to the second embodiment of the present invention shown in FIG. Since this chip resistor provides a larger external electrode as compared with the chip resistor of the first embodiment, it is as described above that good mountability can be obtained after being incorporated in the circuit board.

  Next, a manufacturing process of the chip resistor of the modification of the second embodiment of the present invention shown in FIG. 3C will be described with reference to FIG. In this chip resistor, the resistive film 13 is disposed in the lowest layer on the substrate surface, the internal electrodes 12a and 12b are omitted, and the second internal electrodes 19a and 19b are directly connected to the resistive film 13. This is different from the chip resistor shown in FIG.

  For this reason, as shown in FIG. 6B, a resistance film 23 is disposed on the surface of a large substrate, and a glass layer 26 is disposed on the back surface. Then, the glass protective film 17 is disposed as shown in FIG. 6C, and the second internal electrode 19 is placed on the resistance film 23 so as to cover both ends of the glass protective film 17 as shown in FIG. 6D. To place. Then, trimming is appropriately performed for each section of the resistance film 23 as shown in FIG. 6E, and the resin protective film 18 is covered so as to cover a part of the second internal electrode 19 as shown in FIG. Form.

  Then, the large-sized substrate 21 is divided into chip-piece substrates 11 by the primary break and the secondary break, and Ni plating and Cu plating are applied to the surfaces of the second internal electrodes 19a and 19b. 14b and the Cu plating layers 15a and 15b, the chip resistor shown in FIG. 3C is completed. As described above, this chip resistor can be reduced in height as compared with the chip resistor shown in FIG.

  FIG. 7 shows an example of the interior of the chip resistor of the present invention on a laminated circuit board. In this example, the laminated circuit board 31 is formed by laminating boards 31a, 31b, and 31c, and the chip resistor of the present invention is housed in a recess provided in the board 31b. In this chip resistor, a resistive film is disposed on the surface of the insulating substrate 11, the resistive film is covered with a protective film 18, and external electrodes 18 having a Cu plating layer on the surface are disposed on both sides thereof. A glass layer 16 that is a thick film fired body is disposed on the back side of the insulating substrate 11.

  A wiring layer 32 is provided in the inner layer of the multilayer circuit board 31 and is connected to the external electrode 15 of this chip resistor. The chip resistor is bonded to the upper substrate 31 a via an adhesive 33. This chip resistor has an extremely thin thickness (height) of 150 μm or less, and has a glass layer 16 as a reinforcing material on the back surface and has sufficient mechanical strength. It is suitable as a resistor for use.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

  The chip resistor of the present invention can be suitably used as a resistor for interior of a circuit board that is required to be light and thin.

Claims (7)

An insulating substrate having a thickness of 100 μm or less having a front surface and a back surface;
An internal electrode made of a pair of thick film fired bodies formed on the surface of the substrate;
A resistive film made of a thick film fired body formed between the pair of internal electrodes;
A chip resistor with a built-in substrate, comprising: a glass layer or a metal layer made of a thick film fired body formed on the back surface of the substrate.   The chip resistor for a substrate according to claim 1, wherein the height of the resistor is 150 μm or less.   The resistance film is covered with a protective film, and a second internal electrode made of a conductive resin film is provided on a part of the protective film and the internal electrode, and a plating layer is provided on the surface of the second internal electrode. The chip resistor for a substrate according to 1. Preparing a large-sized insulating substrate having a thickness of 100 μm or less having a front surface and a back surface;
Forming an internal electrode made of a thick film fired body in each section of the surface of the large substrate;
A glass layer or a metal layer made of a thick film fired body is formed on the back surface of the large substrate,
Forming a resistive film made of a thick film fired body connected to the internal electrode;
Forming a protective film covering the resistive film;
Dividing the large substrate into chip pieces for each compartment;
A method of manufacturing a chip resistor for incorporating a substrate, wherein a plating layer is formed on the electrode surface of the chip piece. Preparing a large-sized insulating substrate having a thickness of 100 μm or less having a front surface and a back surface;
Forming a resistive film made of a thick film fired body in each section of the surface of the large substrate;
A glass layer or a metal layer made of a thick film fired body is formed on the back surface of the large substrate,
Forming an internal electrode made of a thick film fired body connected to the resistance film;
Forming a protective film covering the resistive film;
Dividing the large substrate into chip pieces for each compartment;
A method of manufacturing a chip resistor for incorporating a substrate, wherein a plating layer is formed on the electrode surface of the chip piece.   6. The method of manufacturing a chip resistor with a built-in substrate according to claim 4, wherein a split groove is formed in the large substrate.   The second internal electrode made of a conductive resin film is formed on a part of the protective film and the internal electrode, and a plating layer is formed on the surface of the second internal electrode. A method of manufacturing a chip resistor for a substrate.

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