JP2014060435A - Substrate built-in chip resistor and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for substrate built-in chip resistor having a wide and flat electrode surface on the surface, and an internal electrode of conventional structure on the substrate surface, which ensures wide resistance characteristics while enhancing the mountability.SOLUTION: An insulating large-sized substrate 11 having front and back surfaces is prepared, a pair of internal electrodes 12 are formed in each section on the surface of the large-sized substrate, a resistance film is formed in each section so as to connect the pair of internal electrodes, a first protective film 17 is formed so as to expose at least a part of the internal electrode, a second protective film 18 is formed so as to cover the region where the resistance film is formed at least partially, and connected with the exposed part of the internal electrode, a second internal electrode 14 is formed to cover the end of the second protective film, while having a wide and flat electrode surface, and a plating layer 15 is formed on the surface of the second internal electrode, so that the upper surface of the plating layer is higher than the upper surface of second protective film.

Description

  The present invention relates to a chip resistor, and more particularly to a substrate built-in chip resistor that is built in a laminated circuit board or the like and is extremely thin, and a method of manufacturing the same.

  As electronic devices become lighter, thinner, and smaller, not only chip resistors and other electronic components are mounted on the front and back surfaces of circuit boards, but also on the inner layer of laminated circuit boards, etc. A configuration example has been proposed (see Patent Document 1). In the chip resistor with a built-in substrate mounted on the laminated circuit board or the like, the thickness is preferably as thin as possible, and it is preferable to dispose the electrode, the resistor, and the protective film only on one side from the viewpoint of thinning.

  In addition, in a chip resistor for a substrate, the resistor may be embedded inside an insulating layer such as a laminated circuit board and connected to a circuit wiring layer disposed on the surface of the insulating layer via a via. It may be formed by etching by laser beam irradiation (see Patent Document 2).

  For this reason, it is desirable that the size of the electrode of the resistor is wide and that the flatness of the electrode surface is good. However, if the electrodes are widened while maintaining the structure of the conventional chip resistor, the distance between the two electrodes is reduced, and the region where the resistor is formed is limited, so that it is difficult to maintain the same rating as the conventional one. However, there is a problem that it becomes an obstacle to manufacture resistors having a wide range of resistance characteristics.

JP 2004-140285 A JP 2008-288607 A

  The present invention has been made based on the above-mentioned circumstances, and has a wide and flat electrode surface on the surface, and the internal electrode on the substrate surface has a conventional structure, so that a wide range of resistance characteristics can be obtained and mountability can be obtained. It is an object of the present invention to provide a chip resistor with a built-in substrate with improved resistance.

  According to the method for manufacturing a chip resistor for a substrate of the present invention, an insulating large-sized substrate having a front surface and a back surface is prepared, a pair of internal electrodes is formed in each section of the surface of the large-sized substrate, and the pair of internal resistors A resistive film is formed in each partition so as to connect the electrodes, the first protective film is formed so as to cover the entire resistive film and to expose at least a part of the internal electrode, and the resistive film is formed. Forming a second protective film covering at least a part of the region, connecting the exposed portion of the internal electrode, and forming a second internal electrode so as to cover an end of the second protective film; Has a wide and flat electrode surface, a plating layer is formed on the surface of the second internal electrode, and the upper surface of the plating layer is formed higher than the upper surface of the second protective film.

  As a result, the internal electrode remains in the conventional structure, and a wide range of resistance characteristics can be obtained without reducing the distance between the two electrodes. Then, by providing a second internal electrode connected to the internal electrode and disposed on the upper surface of the electrode and the protective film end, the distance between the two electrodes can be narrowed. Thus, the second internal electrode having a large area can be obtained, and the mounting property can be improved when mounting on the inner layer of the laminated circuit board or the like.

BRIEF DESCRIPTION OF THE DRAWINGS (a) of the board | substrate chip resistor of Example 1 of this invention is sectional drawing, (b) is a top view, (c) is a bottom view. It is sectional drawing of the chip resistor for a board | substrate of Example 2 of this invention. It is a top view which shows the manufacturing process of this resistor of this invention. Similarly, it is a top view which shows the manufacturing process of this resistor of this invention. It is sectional drawing which shows an example of the process of incorporating this resistor in the laminated circuit board of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 5. 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 FIG. 1, the chip resistor with a built-in substrate of the present invention has an Ag-Pd having a thickness of about 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, 12b made of a thick film fired body such as RuO ₂ is disposed between the pair of internal electrodes 12a and 12b. The resistance film 13 is covered with a first protective film 17 made of a glass coat and a second protective film 18 made of an overcoat such as an epoxy resin.

  That is, the protective film includes a first protective film 17 that is formed on the resistive film 13 and covers the entire resistive film, and a second protective film 18 that is formed on the first protective film and covers the portion other than the end portion. The length of the first protective film 17 in the direction is longer than the length of the second protective film 18. The first protective film 17 is formed so that at least a part of the internal electrodes 12a and 12b is exposed. The second protective film 18 covers at least a part of the region where the resistance film 13 is formed, and is formed in a range that does not overlap the internal electrodes 12a and 12b. Thereby, since the 2nd protective film is short, the increase in the height dimension by recoating can be reduced, and the height dimension in an electrode formation part can be made uniform.

  A pair of second internal electrodes 14a and 14b are provided which are connected to the exposed portions of the internal electrodes 12a and 12b and are formed so as to cover the ends of the electrodes 12a and 12b, the protective film 17 and the protective film 18. The thickness of the second internal electrodes 14a, 14b is about 20 μm. The second internal electrodes 14a and 14b are conductive resins containing Ni as a main conductive material in Example 1, and are formed by applying a paste of the conductive resin by screen printing and heating and curing. . Since it is a conductive resin paste, the unevenness of the lower layer is absorbed, the surface flatness is high, and a wide electrode area covering the second protective film 18 is obtained. Thus, the distance between the pair of second internal electrodes 14a and 14b can be made narrower than the distance between the pair of internal electrodes 12a and 12b, and a wide electrode area and flatness can be obtained. can get.

  The second internal electrodes 14a and 14b are covered with external electrodes 15a and 15b made of a Cu plating layer having a thickness of about 7 μm, respectively. The external electrodes 15a and 15b function as a stopper layer for protecting the internal electrode and the second internal electrode from the impact of the laser beam when forming vias by laser beam etching during mounting, and for the wiring layer of the circuit board. Good connectivity is obtained.

  The width of the second internal electrodes 14a and 14b in the direction orthogonal to the current direction is preferably larger than the width of the internal electrodes 12a and 12b, and is equal to the width of the insulating substrate 11 (FIG. 4 ( d)). Thereby, the area of the external electrodes 15 and 15 can be increased, and the flatness of the external electrode surface can be improved.

  On the back surface side of the insulating substrate 11, markings 19a and 19b made of characters, figures or symbols are formed. The markings 19a and 19b are preferably provided immediately below the center of the external electrodes 15a and 15b. Thus, it can be used as a mark for alignment when forming a via by laser beam etching during mounting.

  In the case of a built-in chip resistor, after embedding in the insulator of the circuit board, a laser beam is irradiated to form a via in the insulating layer covering the chip resistor to expose the external electrode and connect to the external wiring The external electrode is preferably as large as possible for via formation. In this embodiment, the effective area of the internal electrodes 12a and 12b (effective area for electrical connection to the outside. That is, the resistance film 13 is also protected, which is suitable for mounting a chip resistor embedded in the insulator of the circuit board. A chip resistor with a built-in substrate including the second internal electrodes 14a and 14b larger than the region not covered by the film 17 can be formed. In addition, since the interval between the second internal electrodes 14a and 14b is narrower than the interval between the effective regions of the internal electrodes 12a and 12b, the second internal electrodes 14a and 14b that are large within a limited range of a minute chip are formed. be able to.

  With the above configuration, a thin chip resistor suitable for being built in a circuit board and having a thin external electrode only on the surface of the board 11 can be 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). It can be made thinner than the thickness of the resistor, for example, about half the thickness of about 60 to 150 μm.

  FIG. 2 shows a chip resistor with a built-in substrate according to a second embodiment of the present invention. The chip resistor includes second internal electrodes 14c and 14d that are connected to the internal electrodes 12a and 12b and have a larger area than the effective area of the internal electrodes 12a and 12b. In Example 2, the second internal electrodes 14c and 14d are made of a conductive resin containing Ag as a main conductive material, and Ni plated layers 15c and 15d and Cu plated layers 15e and 15f are formed on the electrodes. It is. In Example 2, as in Example 1, the second internal electrode is formed of a conductive resin containing Ni as a main conductive material, and a Cu plating layer is formed on the second internal electrode. Good.

  Also in the second embodiment, as in the first embodiment, the internal electrodes 12a and 12b are partially covered with the resistance film 13 and the protective film 17, respectively. The regions of 12a and 12b that are not covered with the resistance film 13 and the protective film 17 become narrower than the actual print pattern of the internal electrodes 12a and 12b. Therefore, by connecting the internal electrodes 12a and 12b and forming the second internal electrodes 14c and 14d so as to overlap the end portions of the protective film 17 and the protective film 18, a large area for conducting to the outside is secured. Can do.

  Next, an embodiment of the manufacturing process of the chip resistor of the present invention will be described. First, as shown in FIGS. 3 (a) and 3 (b), a large format made of ceramic such as alumina having a front surface (FIG. 3 (a)) and a back surface (FIG. 3 (b)) of about 100 μm or less. An insulating substrate 11 is prepared. This substrate 11 is provided with vertical and horizontal dividing grooves x and y, and can be divided into chip pieces for each section after device formation. The dividing grooves x and y are formed by embossing or a laser processing machine.

  As an example, a glass paste is screen-printed on the back surface of the substrate 11 and dried and fired to form a marking 19 made of a thick film fired body. However, the marking 19 may be formed after formation of the internal electrode 12 described later, and the marking 19 may be formed by printing or the like in the final process. As another example of the method of forming the marking 19, the back surface of the substrate 11 may be irradiated with a laser to mark the laser irradiation traces, and an epoxy resin may be formed on the entire back surface of the substrate 11 or the marking formation region. The marking 19 may be formed by forming a film such as the above, and irradiating the film with a laser to change the color of the film.

  Next, as shown in FIG.3 (c), the internal electrode pattern which straddles each division of the surface of the board | substrate 11 is formed by the screen printing of Ag-Pd paste, and after baking, it is fired from a thick film fired body. The internal electrode 12 is formed.

Next, as shown in FIG. 3 (d), a thick film fired body is formed by forming a resistive film pattern straddling the internal electrodes 12, 12 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. 3E, a glass protective film pattern that covers the entire resistance film 13 is formed by screen printing by screen printing of glass paste, dried, and fired after drying. A glass protective film (first protective film) 17 made of a thick film fired body to be coated is formed.

  Next, as shown in FIG. 3F, laser trimming is appropriately performed to adjust the resistance value. A symbol T in the figure indicates a trimming mark. Then, as shown in FIG. 4A, using a resin paste such as an epoxy resin, a resin protective film pattern that covers other than the edge of the glass protective film 17 is formed by screen printing, and is heated and cured. Thus, a resin protective film (second protective film) 18 covering the glass protective film is formed. In this embodiment, the second protective film is formed in a strip-like pattern extending over adjacent sections in a predetermined direction (in the dividing groove y direction). The protective film 18 may not be strip-shaped (does not straddle the dividing groove x) and may be partitioned for each section. However, in order to ensure the flatness of the surface of the second protective film, the protection film 18 may be divided into sections. It is preferable to use a crossing strip pattern.

  Next, as shown in FIG. 4B, a conductive resin paste containing Ni as a main conductive component is screen-printed along the divided grooves y so as to overlap the end portion of the second protective film 18, A band-shaped second internal electrode pattern is formed on a part of the protective films 17, 18 and the internal electrode 12, and is heated and cured to form a band-shaped second internal electrode 14 made of a conductive resin containing Ni as a main conductive component. Form. The second internal electrode 14 may not be strip-shaped (does not straddle the dividing groove x) and may be partitioned for each section. However, in order to ensure the flatness of the surface of the second internal electrode 14 as well. It is preferable to use a belt-like pattern extending over the sections.

  Then, the large-sized insulating substrate 11 is subjected to a primary break along the dividing groove y to form a strip-shaped substrate (see FIG. 4C), and then the strip-shaped substrate is subjected to a secondary break along the dividing groove x. The large insulating substrate 11 is divided into chip pieces (see FIG. 4D). Further, Cu plating layers 15a and 15b serving as external electrodes are formed by forming a Cu plating film on the surfaces of the second internal electrodes 14a and 14b by electrolytic plating. At this stage, the chip resistor according to the first embodiment of the present invention shown in FIG. 1 is completed. In this chip resistor, since a large and flat external electrode can be obtained as compared with the conventional chip resistor, good mountability can be obtained for incorporation in a laminated circuit board or the like.

  Regarding the manufacturing process of the chip resistor of Example 2 of the present invention, after the resin protective film 18 is formed, a conductive resin paste containing Ag as a main conductive component is screen-printed, and a part of the protective films 17 and 18 is formed. A second internal electrode pattern is formed on the internal electrode 12 and is heated and cured to form the second internal electrode 14 made of a conductive resin mainly composed of Ag.

  Then, the large-sized substrate 11 is divided into chip-piece substrates 11 by the primary break and the secondary break, and a Ni plating film is formed on the surfaces of the second internal electrodes 14a and 14b by electrolytic plating. By forming a Cu plating film, the external electrodes 15 and 15 comprising the Ni plating layers 15c and 15d and the Cu plating layers 15e and 15f are formed. At this stage, the chip resistor according to the second embodiment of the present invention shown in FIG. 2 is completed. Even with this chip resistor, a large and flat external electrode can be obtained in the same manner as the chip resistor of the first embodiment.

  FIG. 5 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 is formed by laminating insulating sheets 31a and 31b, and the chip resistor of the present invention is built therein. 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, and external electrodes 15 having a Cu plating layer on the surface are disposed on both sides thereof. Is a chip resistor shown in FIGS. 1 and 2 which is formed larger than the internal electrode as described above. Below, an example of the process of mounting the chip resistor of this invention in a laminated substrate is demonstrated.

  As shown in FIG. 5A, a chip resistor is fixed to the insulating sheet 31a with an adhesive 35. Next, as shown in FIG.5 (b), the sheet | seat 31b in which the through-hole which accommodates a chip resistor was formed was piled up on the sheet | seat 31a, and also the transparent sheet | seat 31c was piled up, and a laminated body is obtained. Then, this laminated body is pressed by a technique such as an isostatic pressing method, and each sheet and the built-in chip resistor are brought into close contact. FIG.5 (c) is the figure which turned upside down after pressing the laminated body shown in FIG.5 (b). The marking 19 printed on the substrate 11 of the chip resistor is confirmed using an image recognition device (reference numeral C), the irradiation position of the laser L is aligned, and the sheet 31a is irradiated with the laser L for etching. The sheet 31c is a resin sheet or the like that is transparent to the extent that at least the marking 19 can be confirmed from the outside.

  Since the chip resistor according to the present invention includes the external electrode 15 having a large area, the allowable area for etching is widened and mounting is easy, and the laser 19 can be aligned with the marking 19 by mistake. The occurrence of defects due to laser irradiation or the like can be prevented. In addition, since the marking 19 is formed on the back side of the substrate 11 of the chip resistor, the formation of the marking 19 does not affect the electrode, which is preferable without affecting the electrode dimensions, conductivity, and the like.

  Thus, a via hole 37 is formed as shown in FIG. The external electrode 15 is exposed in the via hole 37. Next, as shown in FIG. 5E, a conductive material is filled in the via hole 37 to form the via 33, and the wiring 32 connected to the via 33 is printed on the surface of the sheet 31a. The laminated body thus obtained can be multi-layered by further stacking sheets and forming interconnections and interlayer connection by vias.

  In the above-described embodiment, the example in which the second internal electrode is formed of a conductive resin made of a metal material of Ni or Ag and a resin component has been described. However, the conductive resin having other metal material as a main conductive component. It can also be formed. By forming the second internal electrode with a conductive resin, it absorbs irregularities such as convex portions due to the overlapping of the lower internal electrode 12, the resistance film 13 and the first protective film 17, and the surface is flat and has a wide area. The second internal electrode 14 can be formed.

  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 is connected to an internal electrode formed on the surface of a substrate, and has a large area and a flat second internal electrode disposed on the upper surfaces of the electrodes and the end portions of the first and second protective films. And the external electrode formed on the surface thereof, it is easy to mount on a laminated circuit board or the like. Therefore, it can be suitably used as a chip resistor for interior use in a laminated circuit board or the like that requires high mounting density.

Claims (5)

Prepare an insulating large-format substrate having a front surface and a back surface,
Forming a pair of internal electrodes in each section of the surface of the large substrate;
Forming a resistive film in each section so as to connect the pair of internal electrodes;
Covering the entire resistance film and forming a first protective film so that at least a part of the internal electrode is exposed;
Forming a second protective film covering at least a part of the region where the resistance film is formed;
A second internal electrode is formed so as to connect to an exposed portion of the internal electrode and cover an end portion of the second protective film, and the second internal electrode has a wide and flat electrode surface,
A method of manufacturing a chip resistor for a substrate, wherein a plating layer is formed on a surface of the second internal electrode, and an upper surface of the plating layer is formed higher than an upper surface of the second protective film.   2. The manufacturing of the chip resistor for a substrate according to claim 1, wherein the resistance value is adjusted by removing a part of the resistance film after the formation of the resistance film and before the formation of the second internal electrode. Method.   The manufacturing method of the chip resistor for board | substrate incorporation of Claim 1 which forms the marking which consists of a character, a figure, or a symbol on the back surface of the said large-sized board | substrate before or after the said internal electrode formation. The internal electrodes are formed in a pattern that is separated from adjacent sections in a predetermined direction;
2. The method of manufacturing a chip resistor for a substrate according to claim 1, wherein the second internal electrode is formed in a strip-like pattern extending over adjacent sections in a predetermined direction.   2. The method of manufacturing a chip resistor with a built-in substrate according to claim 1, wherein the second internal electrode is formed by applying a conductive resin paste by screen printing and heating and curing. 3.

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