JP2002208502A - Chip resistor unit and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip resistor unit which is capable of being mounted on the surface of a printed circuit board or the like even if not only the top or underside but also side of the chip resistor is sucked up by the suction surface of a mounting device, and furthermore which is capable of being mounted on a narrow land part. SOLUTION: A chip resistor unit is equipped with a ceramic base body 11, a pair of top surface electrodes 12 and 12 provided to the lengthwise edges of the ceramic base body 11 respectively, a resistor 13 which spreads over the surface of the ceramic body 11 between the top surface electrodes 12 and 12, and furthermore external electrodes 21, 22, 23, and 24 which are solderable are arranged on the top surface, underside, and both lateral sides of the lengthwise edges of the chip resistor unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a chip resistor suitable for surface mounting, and more particularly to an electrode structure thereof.

[0002]

2. Description of the Related Art FIG. 3 shows an example of the structure of a conventional chip resistor. The chip resistor 10 includes a ceramic substrate 11 made of alumina or the like and a pair of upper electrodes 12, 12 disposed on the upper surface of the substrate 11, as shown in FIG.
And a resistor 13 disposed so as to straddle the pair of upper electrodes 12. Then, as shown in (b) of the completion stage, the protective film 1 is formed on the resistor 13.
5 is provided to cover and protect the resistor 13. As shown, external electrodes 16, 17, and 18, which can be soldered to the upper surface, the lower surface, and the end surface, are arranged at both ends in the longitudinal direction of the ceramic base 11. Here, the upper surface electrode 12 and the lower surface electrode over which the resistor extends are formed by forming Ag or Ag-Pd paste by thick-film screen printing and then firing at a high temperature. On the other hand, the external electrodes 16, 17, 18 are formed by forming a Ni—Cr film or the like by sputtering or the like, and then applying a plating film such as nickel plating or solder plating.

In the structure of such a chip resistor, solderable external electrodes are continuously formed on three surfaces at both ends in the longitudinal direction of the ceramic base 11, so that the surface mounting on a printed circuit board or the like is performed. It is suitable for. However,
In such a conventional chip resistor, only the upper and lower surfaces (front and back surfaces) can be formed because the external electrodes exist only on the upper and lower surfaces and the end surfaces. For this reason, if the chip component mounter erroneously picks up one of the left and right sides of the chip resistor, it becomes so-called sideways, and since there are no external electrodes at both ends, it is surface mounted on a printed circuit board or the like. And a defective product is produced at the mounting stage.

In addition, the conventional end face electrode has a problem that a fillet is formed on the end face side at the time of mounting, so that the mounting area at that portion becomes large.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and is intended for surface mounting of a printed circuit board or the like even when the suction surface of the mounting machine suctions not only the upper and lower surfaces but also the side surfaces. It is another object of the present invention to provide a chip resistor which can be mounted on a narrow land portion.

[0006]

According to the present invention, there is provided a chip resistor provided with a pair of upper electrodes and a resistor extending between the upper electrodes at both longitudinal ends of the ceramic substrate. External electrodes capable of continuous soldering are arranged on the upper surface, lower surface, and left and right side surfaces at both ends in the direction.

Further, according to a method of manufacturing a chip resistor of the present invention, a sheet-like ceramics substrate provided with a divided groove in a vertical groove is prepared, a lower surface electrode and an upper surface electrode are formed, a resistor is formed, and a resistance value is formed. After performing the adjustment and forming the protective film for covering the resistor, after the division, the primary division is performed along the division grooves which are the longitudinal directions of the individual substrates, and the metal films are formed on both ends of the side surface. A secondary division is performed along a division groove which is a short side direction of the base, and plating is performed.

According to the above-described chip resistor of the present invention,
Since continuous solderable external electrodes are arranged on the upper surface, lower surface, and left and right side surfaces at both ends in the longitudinal direction, the chip resistor can be used even when the mounting machine sucks not only the upper and lower surfaces but also the side surfaces. This allows normal mounting on the land portion of the printed circuit board. Therefore, in a chip component mounting machine, surface mounting can be performed irrespective of the suction surface, so that there is no discarded component due to mounting failure, and the manufacturing cost in the mounting stage can be reduced.

Further, since the side surface of the chip resistor can be mounted on the land portion of the printed circuit board, the mounting can be reliably performed even with a small land pattern.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a chip resistor according to an embodiment of the present invention. The chip resistor includes a pair of upper electrodes 12, 12 at both ends in the longitudinal direction of a ceramic base 11 such as alumina, as shown in FIG.
3 is provided. Further, the lower surface is provided with lower surface electrodes at both ends of the substrate corresponding to the upper surface electrode. Then, the external appearance of the chip resistor is, as shown in FIG.
5, the upper electrode 12 of the substrate 11 is covered by the external electrode 21. Further, external electrodes 22 and 23 are provided on both side surfaces of both ends in the longitudinal direction of the substrate 11, and the lower electrode is also covered on the lower surface. 24 are provided. The electrode does not exist on the longitudinal end face 20 of the base 11.

FIG. 2 shows a manufacturing process of the chip resistor. First, a sheet-like ceramic substrate such as alumina is prepared (reference numeral 31). The lower surface electrode is formed by screen printing, drying, and firing (reference numeral 32). Next, the upper electrode 12 is formed by screen printing, drying and firing (reference numeral 33), and the resistor 13 is formed by screen printing, drying and firing (reference numeral 34). Next, a precoat layer covering the resistor 13 is formed by screen printing, drying, and baking (reference numeral 35), and the resistance value is adjusted by laser trimming or the like (reference numeral 36). Then, the protective film 15 is formed by screen printing, drying, and baking (reference numeral 37). The above steps are the same as the conventional steps for manufacturing a chip resistor.

Next, the primary division is performed (reference numeral 38). In the method of manufacturing the chip resistor of the present invention, the primary division is performed along the division grooves in the longitudinal direction of the base 11 (reference numeral 3).
8). The strip-shaped substrate 11a after the primary division is shown in FIG. Then, as shown in (c), the divided strip-shaped substrates 11a are stacked and mounted on a jig, and covered with the side non-electrode partial mask 26 (reference numeral 39). The mask 26 on the side non-electrode portion is formed by a dedicated jig or resist printing.

Then, by sputtering or vapor deposition,
For example, a metal film such as nichrome is formed on the exposed portion of the side surface of the base (reference numeral 40, see FIG. 2D). The metal film formed by sputtering or the like goes around not only the side surface of the base but also the upper surface and the lower surface, is connected to the upper electrode and the lower electrode, and a metal film continuous with these electrodes is formed. When the mask 26 is removed, the metal film 2
5 are formed (see FIG. 2E).

Next, the rectangular substrate 11a is subjected to secondary division along the division grooves in the lateral direction (reference numeral 41), and individual ceramic bases 11 are obtained. And nickel plating,
A plating process such as solder plating is performed, and external electrodes 21, 22, and 2 are formed on the upper electrode, the side metal film, and the lower electrode.
3, 24 are formed (reference numeral 42).

Thus, the chip resistor having the structure shown in FIG. 1 is completed. According to this chip resistor, the external electrodes 21, 22, which can be soldered to the upper, lower, and side surfaces.
Because of the provision of 23 and 24, it is possible to mount one side surface as a suction surface of a mounting machine and the other side surface on a land on a printed circuit board. Therefore, mounting can be ensured even on a land pattern on a small printed circuit board, and the problem of erroneous suction of a mounting surface in a mounting machine is eliminated, so that defects in the mounting stage can be reduced. .

[0017]

In general, according to the present invention, there is provided a chip resistor capable of mounting not only the upper and lower surfaces but also the side surface to the land portion of the printed circuit board while maintaining the performance and productivity of the chip resistor. Provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an external shape of a chip resistor according to an embodiment of the present invention, wherein (a) shows a step of forming a resistor and (b) shows a completed step.

FIGS. 2A and 2B show a manufacturing process of a chip resistor according to an embodiment of the present invention, wherein FIG. 2A is a flowchart, FIG. 2B is a top view of a substrate divided into strips, and FIG. Figure, (d)
(E) a side view showing the stage after sputter deposition;
It is a side view in the state where the metal film was formed in the side of a substrate.

3A and 3B are perspective views showing the appearance of a conventional chip resistor, wherein FIG. 3A shows a stage of forming a resistor, and FIG. 3B shows a completed stage.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Base 12 Upper electrode 13 Resistor 15 Protective film 16, 17, 18 External electrode 21, 22, 23, 24 External electrode 26 Mask

Claims (2)

[Claims] 1. A chip resistor provided with a pair of upper electrodes at both ends in a longitudinal direction of a ceramic substrate and a resistor extending between the upper electrodes, wherein a top surface of both ends in the longitudinal direction is provided.
A chip resistor characterized by disposing external electrodes that can be continuously soldered on four sides of a lower surface and left and right side surfaces. 2. A sheet-like ceramics substrate provided with a dividing groove in a vertical groove, a lower surface electrode and an upper surface electrode are formed, a resistor is formed, a resistance value is adjusted, and protection for covering the resistor is performed. After the film is formed, the primary division is performed along the division groove that is the longitudinal direction of each substrate after division, metal films are formed at both end portions of the side surfaces, and then along the division groove that is the short direction of the individual substrate. A method of manufacturing a chip resistor, wherein the chip resistor is subjected to a secondary division and a plating process is performed.