JP2017152495A - Chip resistor for board inner layer and component built-in circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a component built-in circuit board capable of reducing surface temperature rise incident to heat generation, while reducing resistance value change caused by flexure stress, and to provide a chip resistor for board inner layer that is built in such a circuit board.SOLUTION: In a component built-in circuit board, a chip resistor 3 is embedded in the resin layer 2 of a base substrate, and a connection via 5 formed in this resin layer 2 is connected with the external electrode of the chip resistor 3. The chip resistor 3 is built in the resin layer 2 while directing the first surface of an insulating substrate, on which a pair of internal electrode and a resistor and a protection film are formed, laterally, and the connection via 5 is connected with the external electrode formed on the second surface adjacent to the first surface and directing upward.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a chip resistor for a substrate inner layer that is used by being embedded in a laminated circuit board or the like, and a component built-in circuit board in which such a chip resistor is embedded in an insulating resin layer.

  In recent years, with the reduction in size and weight of electronic devices and the complexity of circuit configurations, there is a component-embedded circuit board in which chip resistors are mounted not only on the surface of the circuit board but also on the inner layer to increase the component mounting density. It is used for practical use.

  In this type of component built-in circuit board, a chip resistor is usually embedded in a base substrate made of an insulating resin layer, and then a laser beam is irradiated to the resin layer to form a via hole, and the via hole is formed in the via hole. By forming a connection via made of a copper plating process or the like, the connection via is connected to the electrode of the chip resistor formed in the inner layer.

  Conventionally, an external electrode having a large area is formed on the surface of the chip resistor for the inner layer of the substrate, and a via hole is formed toward the external electrode, whereby a wiring pattern on the base substrate is formed via the inner layer of the chip resistor. There has been proposed a component-embedded circuit board that conducts between them (for example, see Patent Document 1).

  The chip resistor disclosed in Patent Document 1 includes a pair of internal electrodes formed on the surface of a rectangular parallelepiped insulating substrate at a predetermined interval, a resistor formed between these internal electrodes, and an internal electrode And a pair of external electrodes formed so as to cover the exposed portion of the internal electrode and the end portion of the protective film. ing.

  When manufacturing a component-embedded circuit board by layering the chip resistor for the substrate inner layer configured as described above on the resin layer of the base substrate, the one side on which the resistor, the external electrode, etc. are formed faces up. After embedding the chip resistor in the resin layer, by forming a via hole extending from the surface of the resin layer to the inside, the wiring pattern on the base substrate and the external electrode of the chip resistor are connected via the via hole. ing. At that time, since the chip resistor has a large external electrode that can be connected to the via hole, even if the formation position of the via hole is slightly deviated from the normal position, the external electrode and the via hole of the chip resistor are It can be securely connected.

JP 2011-91140 A

  In the chip resistor for the substrate inner layer disclosed in Patent Document 1, since the external electrode connected to the via hole is formed on the same surface as the resistor and the internal electrode, in a posture in which the formation surface of the resistor faces upward It is necessary to embed a chip resistor in the resin layer. For this reason, the surface temperature of the resin layer is likely to rise due to the heat generated by the resistor, which adversely affects electronic components surface-mounted on the base substrate and chip components inner layers of other resin layers in the case of multilayer substrates. There was a problem that would affect.

  In addition, in this type of component-embedded circuit board, bending stress may be applied to the insulating substrate of the chip resistor embedded in the resin layer due to warpage of the base substrate, and in this case, the interval between the internal electrodes is increased. When bending stress is applied, the resistance value increases, and conversely, when bending stress is applied that reduces the distance between the internal electrodes, the resistance value decreases. Therefore, the resistance value of the chip resistor changes due to the bending stress applied to the insulating substrate. Will end up. In particular, the chip resistor for the inner layer of the substrate that is used by being embedded in the resin layer is formed with a thin overall thickness including the insulating substrate, so that the deformation in the direction in which the resistor forming surface is bent is prevented. Since the structure is very weak, there is a problem that the resistance value changes greatly with a slight deflection.

  The present invention has been made in view of the above-described prior art, and a first object thereof is to incorporate a component that can reduce an increase in surface temperature due to heat generation and reduce a resistance value change caused by bending stress. To provide a mold circuit board. A second object of the present invention is to provide a chip resistor for an inner layer of a substrate that can reduce an increase in surface temperature due to heat generation and can reduce a change in resistance value caused by bending stress.

  In order to achieve the first object, in the component-embedded circuit board of the present invention, a chip resistor is embedded in the inner layer of the base substrate made of an insulating resin layer, and the chip chip is formed from the surface of the base substrate. In the component-embedded circuit board provided with via holes reaching the resistor, the chip resistor is formed on the rectangular parallelepiped insulating substrate and the first surface, which is one surface of the insulating substrate, with a predetermined interval. A pair of internal electrodes; a resistor formed between the pair of internal electrodes; an insulating protective film formed to cover the resistor; and a second adjacent to the first surface of the insulating substrate. A pair of external electrodes formed on a surface and connected to the internal electrode, wherein the first surface is disposed to face a surface orthogonal to the surface of the base substrate, and the via hole is formed on the base substrate Surface and flat And the configuration that is connected to the external electrodes on the arranged second surface to.

  In the component-embedded circuit board configured as described above, a resin is formed so that the second surface, which is the external electrode forming surface, is parallel to the surface of the base substrate among the six surfaces constituting the insulating substrate of the chip resistor. Since the via hole is connected to the external electrode and the first surface, which is the formation surface of the internal electrode and the resistor, is disposed so as to face the surface orthogonal to the surface of the base substrate. In addition, it is possible to suppress the surface temperature of the resin layer from increasing due to the heat generated by the resistor, and it is possible to suppress the resistance value of the resistor from changing due to bending stress.

  In the above configuration, when the radiator that surrounds the first surface of the chip resistor is embedded in the base substrate, the heat generated by the resistor formed on the first surface is dissipated by the radiator. An increase in surface temperature can be suppressed more effectively.

  In order to achieve the second object, the chip resistor for an inner layer of the present invention is formed with a rectangular parallelepiped insulating substrate and a first surface which is one surface of the insulating substrate with a predetermined interval. A pair of internal electrodes, a resistor formed between the pair of internal electrodes, an insulating protective film formed to cover the resistor, and a first layer adjacent to the first surface of the insulating substrate. A pair of external electrodes formed on two surfaces and connected to the internal electrodes are provided, and an interval between the pair of external electrodes is set narrower than an interval between the pair of internal electrodes.

  In the chip resistor for the substrate inner layer configured as described above, the internal electrode, the resistor, and the protective film are formed on the first surface among the six surfaces constituting the rectangular parallelepiped insulating substrate, and the first surface is formed on the first surface. An external electrode is formed on the adjacent second surface, and the distance between the electrodes of the external electrode is set to be narrower than that of the internal electrode, so that the external electrode having a large area extends on the second surface. Therefore, by embedding the resin layer so that the second surface of the insulating substrate is parallel to the surface of the base substrate, the via hole can be reliably connected to the external electrode formed in a large area on the second surface. it can. Further, when the second surface is arranged so as to be parallel to the surface of the base substrate, the first surface on which the internal electrode and the resistor are formed is arranged so as to face a surface orthogonal to the surface of the base substrate. Therefore, it can suppress that the surface temperature of a resin layer raises by the heat_generation | fever of a resistor, and can suppress that the resistance value of a resistor changes with bending stress.

  In the above configuration, a pair of internal electrodes formed on the first surface opposite to the first surface of the insulating substrate at a predetermined interval, and a resistor formed between the pair of internal electrodes, An insulating protective film formed so as to cover this resistor is formed, and when the external electrode is connected to the internal electrode formed on the two first surfaces, the rating of the chip resistor is set. Can be increased.

  In the above configuration, the protective film only needs to cover at least the resistor, but if the protective film covers the entire resistor and the internal electrode, the chip is formed on the resin layer of the base substrate in order to enhance the heat dissipation effect. Even if the radiator that surrounds the first surface of the resistor is embedded, the contact between the internal electrode and the radiator can be prevented by the protective film.

  According to the present invention, it is possible to provide a circuit board with a built-in component that can reduce a rise in surface temperature due to heat generation and reduce a resistance value change caused by bending stress, and can also increase a surface temperature due to heat generation. It is possible to provide a chip resistor for an inner layer of a substrate that can reduce the resistance value change caused by a bending stress.

1 is a cross-sectional view of a component-embedded circuit board according to a first embodiment of the present invention. It is a perspective view of the chip resistor built in this component built-in type circuit board. It is sectional drawing of this chip resistor. It is a perspective view of the other chip resistor built in the component built-in type circuit board of FIG. It is sectional drawing of the component built-in type circuit board based on 2nd Example of this invention. It is a top view which shows the manufacturing process of this component built-in type circuit board. It is sectional drawing which shows the manufacturing process of this component built-in type circuit board. It is a perspective view of the chip resistor for substrate inner layers concerning the example of a 1st embodiment of the present invention. It is sectional drawing of this chip resistor. It is a perspective view of the chip resistor for substrate inner layers concerning the example of a 2nd embodiment of the present invention. It is a perspective view of the chip resistor for substrate inner layers concerning the example of a 3rd embodiment of the present invention. It is sectional drawing of this chip resistor.

  Hereinafter, embodiments of the invention will be described with reference to the drawings. As shown in FIG. 1, a component-embedded circuit board 1 according to a first embodiment of the present invention has a chip resistor 3 embedded in an inner layer of a base substrate made of an insulating resin layer 2, and this resin A wiring pattern 4 provided on the upper surface of the layer 2 is connected to an external electrode (described later) of the chip resistor 3 through a connection via 5. The connection via 5 is formed by irradiating the resin layer 2 with a laser beam to form a via hole and then performing copper plating or the like in the via hole.

  As shown in FIGS. 2 and 3, the chip resistor 3 formed in the resin layer 2 includes a rectangular parallelepiped insulating substrate 6 and a pair of internal electrodes 7 provided at both ends in the longitudinal direction on one side surface of the insulating substrate 6. A rectangular resistor 8 provided so as to be connected to these internal electrodes 7, and a protective film 9 made of a resin covering the entire side surface of the insulating substrate 6 including both the internal electrodes 7 and the resistor 8, It is mainly constituted by a pair of external electrodes 10 provided at both ends in the longitudinal direction of the insulating substrate 6.

  The insulating substrate 6 is made of ceramics. Of the six surfaces constituting the insulating substrate 6, the two opposing surfaces having the largest area are the first surface, and the two opposing surfaces continuing to the long side of the first surface are the first surfaces. If two opposing surfaces that are continuous with the short sides of the two surfaces, the first surface, are referred to as a third surface, the internal electrode 7, the resistor 8 and the protective film 9 are formed on one first surface, and the external electrode 10 A cap shape is formed so as to cover the first to third surfaces.

  The pair of internal electrodes 7 are obtained by screen-printing Ag-based paste, dried and fired, and these internal electrodes 7 are formed in a rectangular shape at the longitudinal ends of the first surface of the insulating substrate 6.

  The resistor 8 is obtained by screen-printing a resistor paste such as ruthenium oxide, dried and fired, and both ends in the longitudinal direction of the resistor 8 overlap the internal electrode 7. Although not shown, the resistor 8 has a trimming groove for adjusting the resistance value.

  The protective film 9 is an overcoat layer obtained by screen-printing an epoxy resin paste and heat-cured. Although not shown, an undercoat layer that covers the resistor 8 is formed on the lower surface side of the protective film 9. Yes. The undercoat layer is obtained by screen-printing glass paste, drying and firing. Since the protective film 9 is formed so as to cover the entire first surface of the insulating substrate 6 including both the internal electrodes 7 and the resistor 8, the three sides of the pair of internal electrodes 7 are between the insulating substrate 6 and the protective film 9. Is exposed from.

  The pair of external electrodes 10 is obtained by dip-coating Ag paste or Cu paste on the third surface of the insulating substrate 6 and heat-curing. These external electrodes 10 are protective films 9 formed on one first surface. Is formed in a cap shape so as to cover the remaining first surface and part of both second surfaces. Accordingly, the external electrode 10 located on the left side in FIG. 2 is connected to the end face of the left internal electrode 7 exposed from between the insulating substrate 6 and the protective film 9, and the external electrode 10 located on the right side is protected from the insulating substrate 6. It is connected to the end face of the right internal electrode 7 exposed from between the membranes 9. Although not shown, the surface of these external electrodes 10 is subjected to electrolytic plating such as Ni and Cu.

  As shown in FIG. 1, the chip resistor 3 configured as described above has a first surface, which is a formation surface of the internal electrode 7 and the resistor 8, turned sideways and a second surface adjacent to the first surface. Then, a connection via 5 (via hole) is connected to the external electrode 10 formed on the second surface facing upward. Since the first surface, which is the formation surface of the resistor 8, is arranged so as to face the surface orthogonal to the surface of the base substrate, the heat transfer path from the resistor 8 to the surface of the resin layer 2 is long. Thus, an increase in the surface temperature of the resin layer 2 due to the heat generation of the resistor 8 can be suppressed. In addition, since the first surface, which is the formation surface of the resistor 8, is arranged in a direction (lateral orientation) perpendicular to the plate surface of the base substrate (resin layer 2), the chip resistor is caused by warpage of the base substrate or the like. Even if a bending stress is applied to the third insulating substrate 6, the resistance value of the resistor 8 can be prevented from changing.

  In the component-embedded circuit board 1 shown in FIG. 1, the chip resistor 11 shown in FIG. 4 can be used in place of the chip resistor 3 formed in the resin layer 2. The chip resistor 11 is different from the chip resistor 3 shown in FIGS. 2 and 3 in that the two opposing surfaces having the largest area are the second surface, and the two opposing surfaces that are continuous with the long sides of the second surface are provided. Two opposing surfaces that are continuous with the short sides of the first surface and the second surface are defined as a third surface, and a pair of internal electrodes 7, a resistor 8, and a protective film 9 are formed on one elongated first surface. In particular, the rest of the configuration is basically the same.

  When the chip resistor 11 configured as described above is formed in the resin layer 2 of the component-embedded circuit board 1 shown in FIG. 1, the first surface, which is the formation surface of the internal electrode 7 and the resistor 8, is turned sideways. At the same time, after being embedded in the resin layer 2 with the second surface adjacent to the first surface facing upward, the connection via 5 (via hole) is formed with respect to the external electrode 10 formed on the second surface facing upward. Connected. In this case, since the area of the resistor 8 is reduced, the load characteristic is inferior to the chip resistor 3 shown in FIGS. 2 and 3, but the area of the external electrode 10 is increased, and thus the connection reliability with the connection via 5 is improved. improves. Even in this case, since the first surface, which is the formation surface of the resistor 8, is arranged so as to face the surface orthogonal to the surface of the base substrate, the heat from the resistor 8 to the surface of the resin layer 2 can be obtained. The transmission path becomes longer, and an increase in the surface temperature of the resin layer 2 accompanying the heat generation of the resistor 8 can be suppressed. Further, since the first surface, which is the formation surface of the resistor 8, is arranged in a direction orthogonal to the plate surface of the base substrate (resin layer 2), the insulating substrate of the chip resistor 3 is caused by warpage of the base substrate. Even if bending stress is applied to 6, the resistance value of the resistor 8 can be prevented from changing. As described above, the area of each surface of the insulating substrate 6 can be selected according to required specifications such as connection reliability and load characteristics.

  FIG. 5 is a cross-sectional view of a component-embedded circuit board 20 according to the second embodiment of the present invention, and portions corresponding to those in FIG.

  As shown in FIG. 5, in the component-embedded circuit board 20 according to the second embodiment, a heat radiator 22 is embedded in the resin layer 2 of the base substrate together with the chip resistor 21. The outer surface of the chip resistor 21 is surrounded. The chip resistor 21 is the same as the chip resistors 3 and 11 shown in FIG. 2 and FIG. 4, and is arranged so that the first surface, which is the formation surface of the resistor 23, faces the surface orthogonal to the surface of the base substrate. The connection via 5 is connected to the external electrode on the second surface arranged upward. The radiator 22 is made of a copper plate or the like having a good thermal conductivity, and has a through hole 22 a larger than the outer shape of the chip resistor 21. The chip resistor 21 is disposed inside the through hole 22a, and a total of four outer surfaces of the first surface and the third surface face the inner wall surface of the through hole 22a in a non-contact state.

  In the component-embedded circuit board 20 configured as described above, the radiator 22 surrounding the first surface of the chip resistor 21 functions as a heat sink, and the resistor 23 formed on the first surface generates heat. Since heat is radiated by the heat radiating body 22, an increase in the surface temperature of the resin layer 2 can be more effectively suppressed.

  Next, a method for manufacturing the component-embedded circuit board 20 configured as described above will be described with reference to FIGS.

  First, as shown in FIG. 6A and FIG. 7A, a support plate 25 having an adhesive tape 24 attached to one side is prepared, and a radiator 22 having a plurality of through holes 22a is provided in the adhesive tape 24. paste. 6 is a plan view of the support plate 25 as viewed from above, and FIG. 7 is a cross-sectional view taken along the line AA in FIG.

  Next, as shown in FIGS. 6B and 7B, the chip resistor 21 is inserted into the through hole 22 a of the radiator 22, and the second surface of the chip resistor 21 is attached to the adhesive tape 24. Paste to. At that time, the first surface, which is the formation surface of the resistor 23, is inserted into the through hole 22a in a sideward orientation, and the chip resistor 21 and the inner wall surface of the through hole 22a are not in contact with each other. A gap to keep the state is secured. Thereafter, an upper resin layer covering the radiator 22 and the chip resistor 21 as shown in FIGS. 6C and 7C by thermocompression bonding a thermoplastic resin sheet on the radiator 22. 26 is formed. At that time, the upper resin layer 26 is also filled in a gap secured between the inner wall surface of the through hole 22 a and the chip resistor 21.

  Next, as shown in FIG. 7D, after the support plate 25 with the adhesive tape 24 is peeled from the upper resin layer 26, a thermoplastic resin sheet is thermocompression bonded to the lower surface of the upper resin layer 26. As shown in FIG. 7E, a lower resin layer 27 that covers the heat radiator 22 and the chip resistor 21 exposed from the upper resin layer 26 is formed. As a result, the upper resin layer 26 and the lower resin layer 27 are integrated to form the resin layer 2, and at this time, the chip resistor 21 and the radiator 22 are embedded in the resin layer 2.

  Next, as shown in FIG. 7 (f), the upper surface of the resin layer 2 is irradiated with laser light to form a via hole 5 a, and this via hole 5 a is formed on the external electrode formed on the second surface of the chip resistor 21. Connect. Thereafter, the connection via 5 is formed in the via hole 5a by electroless copper plating or the like, and the wiring pattern 4 is formed on the upper surface of the resin layer 2, thereby completing the component built-in circuit board 20 as shown in FIG. To do.

  Next, the substrate inner layer chip resistor 40 according to the first embodiment of the present invention will be described with reference to FIGS. The chip resistor 40 for the substrate inner layer according to the present embodiment is used by being layered on the resin layer 2 of the component built-in circuit boards 1 and 20 shown in FIG. 1 and FIG. 4 is characterized in that the distance L2 between the pair of external electrodes 10 formed on the second surface is set narrower than the distance L1 between the pair of internal electrodes 7 formed on the one surface. This is basically the same as the chip resistor 11 shown in FIG.

  That is, the chip resistor 40 is provided so as to be connected to the rectangular parallelepiped insulating substrate 6, a pair of internal electrodes 7 provided at both ends in the longitudinal direction on one side surface of the insulating substrate 6, and the internal electrodes 7. A rectangular resistor 8, a protective film 9 made of a resin covering the entire side surface of the insulating substrate 6 including both the internal electrodes 7 and the resistor 8, and a pair provided at both longitudinal ends of the insulating substrate 6 The external electrode 10 is mainly configured.

  Of the six surfaces of the insulating substrate 6, the two opposing surfaces having the largest area are the second surface, the two opposing surfaces continuing to the long sides of the second surface are the first surface, and the short sides of the second surface The two opposing surfaces that are continuous with each other are the third surface, and the pair of internal electrodes 7, the resistor 8, and the protective film 9 are formed on one first surface. The pair of external electrodes 10 are formed at both ends in the longitudinal direction of the insulating substrate 6 so as to cover the protective film 9 formed on the first surface, and the interval L2 between the external electrodes 10 is the interval L1 between the internal electrodes 7. Therefore, the pair of external electrodes 10 having a large area extends on the second surface. Although the protective film 9 is formed so as to cover the entire first surface, it is sufficient that at least the resistor 8 is covered.

  Therefore, even in the chip resistor 40 configured as described above, if the first surface, which is the surface on which the resistor 8 is formed, is formed on the resin layer so as to face the side surface orthogonal to the surface of the base substrate, the resistor 8 The rise in the surface temperature of the resin layer due to heat generation can be suppressed, and even if bending stress is applied to the insulating substrate 6 of the chip resistor 40 due to warpage of the base substrate, the resistance value of the resistor 8 changes. Can be suppressed. Moreover, since the pair of external electrodes 10 having a large area extends on the second surface of the insulating substrate 6, via holes can be reliably connected to the external electrodes 10.

  FIG. 10 is a perspective view of the substrate inner layer chip resistor 50 according to the second embodiment of the present invention. The chip resistor 50 is different from the substrate inner layer chip resistor 40 according to the first embodiment. Is that the two first surfaces facing each other of the insulating substrate 6 are the surfaces on which the resistor 8 is formed, and the other configurations are basically the same.

  That is, in the chip resistor 50, a pair of internal electrodes 7, a resistor 8, and a protective film 9 are formed on two opposing first surfaces of the insulating substrate 6, and the internal electrodes on these two first surfaces are formed. 7 and the external electrode 10 formed on the second surface are electrically connected to form a highly rated chip resistor.

  FIG. 11 is a perspective view of a chip resistor 60 for an inner layer substrate according to a third embodiment of the present invention. FIG. 12 is a cross-sectional view of the chip resistor 60. Parts corresponding to those in FIGS. Is attached.

  The chip resistor 60 is different from the substrate inner layer chip resistor 40 according to the first embodiment in that the entire pair of internal electrodes 7 and the resistor 8 formed on the first surface of the insulating substrate 6 is a protective film. 9 is covered and the external electrodes 10 connected to the internal electrodes 7 are formed only on the second surface, and the other configurations are basically the same.

  In the chip resistor 60 according to the third embodiment, the outer surface of the first surface, which is the formation surface of the resistor 8, is covered with the insulating protective film 9 and is opposed to the first surface. Since one first surface and a pair of third surfaces are exposed surfaces of the insulating substrate 6, a chip resistor 60 is provided on the resin layer 2 of the base substrate as in the component built-in circuit substrate 20 shown in FIG. In the case where the surrounding heat dissipating body 22 is formed as an inner layer, even if the heat dissipating body 22 contacts the outer surface of the chip resistor 60, the heat dissipating body 22 and the internal electrode 7 can be prevented from conducting.

DESCRIPTION OF SYMBOLS 1,20 Component built-in circuit board 2 Resin layer 3,11,21 Chip resistor 4 Wiring pattern 5 Connection via 5a Via hole 6 Insulating substrate 7 Internal electrode 8, 23 Resistor 9 Protective film 10 External electrode
22 Radiator 22a Through hole 24 Adhesive tape 25 Support plate 26 Upper resin layer 27 Lower resin layer 40, 50, 60 Chip resistor for substrate inner layer

Claims (5)

In a component-embedded circuit board in which a chip resistor is embedded in an inner layer of a base substrate made of an insulating resin layer, and via holes reaching the chip resistor from the surface of the base substrate are provided,
The chip resistor includes a rectangular parallelepiped insulating substrate, a pair of internal electrodes formed on a first surface, which is one surface of the insulating substrate, with a predetermined interval, and a resistor formed between the pair of internal electrodes. A body, an insulating protective film formed to cover the resistor, and a pair of external electrodes formed on a second surface adjacent to the first surface of the insulating substrate and connected to the internal electrodes With
The first surface is disposed so as to face a surface orthogonal to the surface of the base substrate, and the via hole is connected to the external electrode on the second surface disposed in parallel with the surface of the base substrate. A circuit board with built-in components.   2. The component-embedded circuit board according to claim 1, wherein a heat radiating body surrounding the first surface of the chip resistor is embedded in the base substrate. A rectangular parallelepiped insulating substrate, a pair of internal electrodes formed on the first surface, which is one surface of the insulating substrate, with a predetermined interval, a resistor formed between the pair of internal electrodes, and the resistor And a pair of external electrodes formed on a second surface adjacent to the first surface of the insulating substrate and connected to the internal electrodes.
A chip resistor for an inner layer of a substrate, wherein an interval between the pair of external electrodes is set narrower than an interval between the pair of internal electrodes.   4. The method according to claim 3, wherein a pair of internal electrodes formed on the first surface opposite to the first surface of the insulating substrate at a predetermined interval are formed between the pair of internal electrodes. A resistor and an insulating protective film formed so as to cover the resistor are formed, and the external electrodes are connected to the internal electrodes formed on the two first surfaces, respectively. A chip resistor for an inner layer of a substrate.   5. The chip resistor for an inner layer of a substrate according to claim 3, wherein the protective film covers the resistor and the whole internal electrode.