JPH0722221A - Production of fixed resistor - Google Patents

Abstract

(57) [Summary] (Modified) [Objective] To provide a method for manufacturing a fixed resistor which has excellent surface smoothness, minimizes fluctuations in resistance value, and does not cause electrode peeling. According to the present invention, the surface side terminal electrode films 31a, 31
b is formed by printing and baking conductive paste a plurality of times; forming the resistor film 4 by printing and baking the resistor paste so as to connect only to the lower layer 310 of the terminal electrode film; And a step of forming an insulating film 5 so as to cover the resistor film 4 by printing and baking an insulating paste, and a method of manufacturing a fixed resistor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a fixed resistor such as a chip resistor and a multiple resistor, and more particularly to a method for manufacturing a fixed resistor having a small change in resistance value and a high surface smoothness. It is about.

[0002]

2. Description of the Related Art Conventionally, in a fixed resistor, for example, a chip resistor, terminal electrodes are arranged at opposite ends of a rectangular insulating substrate made of alumina or the like, and are arranged so as to overlap a part of these two terminal electrodes. A resistor film, which is trimmed and whose resistance value is adjusted, is arranged, and an insulating film is further formed on the resistor film.

On the surface of the substrate of the conventional chip resistor, mainly one terminal electrode portion is formed with only one layer of the conductor film, and the resistor film portion is formed with two layers of the resistor film and the insulating film. Has been formed. Further, depending on the structure, the insulating film may have a two-layer structure, but after all, the thickness on the substrate is different mainly between the part where the terminal electrode is formed and the part where the resistor film is formed, and as a whole. Had poor surface smoothness.

If the surface smoothness of the chip resistor is poor as described above, the chip resistor is automatically mounted on the printed wiring board. Therefore, when the surface of the chip resistor is sucked, suction leakage occurs and the mounting efficiency is lowered. Will end up.

Therefore, in order to improve the smoothness of the surface,
Conventionally, a dummy electrode film is formed on the surface side of the terminal electrode in order to correct the thickness.

For example, in FIG. 4, 1 is a chip resistor, 2 is an insulating substrate, 3a and 3b are terminal electrodes, 4 is a resistor film, and 5 is an insulating film.

Here, the terminal electrodes 3a and 3b are the thick film conductor films 30a and 30b connected to the front surface, the back surface and the end surface of the opposite ends of the insulating substrate, and the dummy electrode film 35a formed on the front surface side thick film conductor film. , 35b and the thick conductor films 30a, 3b.
0b and the plating layers 34a and 34b covering the entire surfaces of the dummy electrode films 35a and 35b.

The outline of the steps of the method of manufacturing the chip resistor shown in FIG. 4 is as follows.

(1) A large-sized insulating substrate having a dividing groove for dividing the element region is prepared. (2) The front surface side and back surface side electrode films, which become part of the terminal electrodes, are formed in each element region by printing and baking a conductive paste.

(3) Printing a resistor paste on a resistor film which is connected to a part of the surface side terminal electrodes facing each element region.
It is formed by firing.

(4) A first insulating film is formed on the resistor film in each element region by printing and baking an insulating paste.

(5) While measuring the resistance value of the resistor film,
The resistance value is adjusted by trimming a part of the resistor film.

(6) On the resistor film in each element region, that is, the first
A second insulating film is formed on the second insulating film by printing and baking an insulating paste.

(7) A dummy electrode film is formed on the surface-side electrode film of each element region by printing and baking a conductive paste.

(8) The large-sized substrate is first divided into strips so that the end surfaces of the respective element regions on the terminal electrode side appear.

(9) The end surface electrode film is formed so that the front surface side electrode film and the back surface side electrode film in each element region are connected.

(10) Two strip-shaped substrates are provided in each element region.
Next division is performed.

(11) A plating layer is formed on the surface of the front surface side electrode film, the back surface electrode film and the end surface electrode film of each element.

[0019]

In order to improve the smoothness of the surface as described above, in the chip resistor in which the dummy electrode film is formed, the dummy electrode films 35a and 35b are formed after the resistance value is adjusted. It

Here, the dummy electrode films 35a and 35b and the second-layer insulating film 52 are formed by printing and baking a conductive paste or an insulating paste. Therefore, the resistance film 4 whose resistance value has been adjusted is subjected to a plurality of heat treatment steps thereafter, so that the resistance value varies each time, and eventually the resistance value adjusted in the trimming step is changed. The resistance value may fluctuate greatly.

Since the dummy electrode films 35a and 35b are formed after the insulating film 5 is formed, part of the dummy electrode films 35a and 35b cover the insulating film 5 as shown in FIG. Resulting in. Therefore, the adhesiveness is deteriorated at this joint portion, which causes a problem such as electrode peeling.

The present invention has been devised in view of the above-mentioned problems, and an object thereof is to have excellent surface smoothness, to minimize fluctuations in resistance value, and to cause peeling of electrodes. It is to provide a manufacturing method of a fixed resistor which does not exist.

[0023]

According to the present invention, a pair of terminal electrodes having a multilayer structure, a resistor film between the pair of terminal electrodes, and the resistor In a method of manufacturing a fixed resistor formed by forming an insulating film on a body film, the step of forming the terminal electrode by printing and baking a conductive paste a plurality of times, and connecting only the lower layer of the terminal electrode. And a step of forming a resistor film by printing / baking a resistor paste, and a step of forming an insulating film by printing / baking an insulating paste so as to cover the resistor film. is there.

[0024]

As described above, the conventional dummy electrode film for improving the surface smoothness is formed by post sintering (post-baking), whereas in the present invention, the shape of the electrode film on the surface side is changed. Of two different prints, drying and baking. At this time, since the lower layer and the upper layer of the terminal electrode are formed by one-time firing by printing twice, they are substantially integrated and the problem of peeling the dummy electrode film unlike the conventional case does not occur.

Further, as described above, since the upper layer of the electrode film on the surface side for improving the surface smoothness is already formed (baked) before the resistance value adjusting step, the heat treatment step after the resistance value adjusting is reduced. Therefore, the fluctuation of the adjusted resistance value can be minimized.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a fixed resistor according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a plan view of a chip resistor which is an example of a fixed resistor according to the present invention, and FIG.
It is a figure which shows the XX cross section in the inside.

The chip resistor 1 is composed of an insulating substrate 2, terminal electrodes 3a and 3b, a resistor film 4 and an insulating film 5.

The insulating substrate 2 is made of an insulating material such as alumina, and the terminal electrodes 3 are provided at opposite ends in the long side direction.
a and 3b are formed.

The terminal electrodes 3a and 3b have respective terminal electrode films 31a to 33a and 31b to 3 formed on the front surface, the back surface and the end surface.
3b, and plated layers 34a and 34b for improving solder wettability are formed on the surface thereof.

Further, the surface side terminal electrode films 31a, 31b
Is a lower layer 310 and an upper layer 311. The lower layer 310 is for achieving the connection with the back surface electrode films 32a and 32b and the end surface electrode films 33a and 33b, and the upper layer 311 is for achieving the surface smoothness of the completed chip resistor 1.

The above-mentioned electrode films 31a to 33a and 31b to 3
3b is printed with Ag-based conductive paste twice on the surface side of the end of the insulating substrate 2 (the lower layer 310 is printed by the first printing and the upper layer 311 is printed by the second printing), dried, and on the back side and the end surface. Each is formed by printing, drying, and baking using an Ag-based conductive paste, and a Ni plating layer and a solder plating layer are further formed by plating.

The resistor film 4 is formed by printing and baking, for example, a ruthenium oxide-based resistor paste so as to be connected to mainly the lower layer 310 of the terminal electrode films 31a and 31b on the surface side of the terminal electrodes 3a and 3b. It is adhered and formed.

The insulating film 5 has a one-layer or two-layer structure. For example, in the case of a two-layer structure, immediately after forming the resistor film 4, the first-layer insulating film 51, at least the resistor film is formed. 4 is deposited and formed on the entire resistor film 4 so as to include the trimmed portion 41.

Further, the second-layer insulating film 52 is deposited so as to sufficiently cover the resistor film 4. First
The insulating film 51 of the layer is formed to reduce the impact on the resistor film 4 at the time of trimming with laser light or the like. The second insulating film 52 is formed to protect the resistor film 4 from the plating solution.
The resistor film 4 is formed by either or both of the first and second insulating films 51 and 52.
It is covered by a larger size print formation.

Next, a method of manufacturing the chip resistor shown in FIG. 1 will be described.

(1) A large-sized insulating substrate having a dividing groove for dividing the element region is prepared. (2) Printing and drying a conductor film, which becomes the surface side electrode films 31a and 31b, which become part of the terminal electrodes 3a and 3b, in each element region, using Ag-based conductive paste. Specifically, FIG.
As shown in (2), first, the lower layer 310 is printed, and then the upper layer 311 having a predetermined shape is printed.
The upper layer 311 may be printed a plurality of times in consideration of the surface smoothness of the completed chip resistor.

(3) An Ag-based conductive paste is printed and dried on each element region to form a conductor film to be the back-side electrode films 32a and 32b which will be a part of the terminal electrodes 3a and 3b.

(4) Surface side and back side electrode films 31a, 3
The conductor films 1b, 32a and 32b are baked on an insulating substrate at 850 ° C.

(5) Forming the resistor film 4 mainly connected to the lower layer 310 of the surface side terminal electrode films 31a and 31b facing each other in each element region. Specifically, a ruthenium oxide-based resistor paste is printed, dried, and fired at 850 ° C.

(6) The first-layer insulating film 51 is formed on the resistor film 4 in each element region. Specifically, an insulating paste containing lead borosilicate glass is printed, dried, and fired at 600 ° C.

(7) While measuring the resistance value of the resistor film 4, a part of the resistor film 4 is trimmed to adjust the resistance value. Specifically, while applying a probe of a measuring device to the front-side electrode films 31a and 31b, for example, a YAG laser is applied to the resistor film 4 in a transverse direction so that the resistor film 4 and the first-layer insulating film are irradiated. A part of 51 is erased.

(8) A second insulating film 52 is formed on the resistor film 4 whose resistance value is adjusted in each element region, that is, on the first insulating film 51. Specifically, an insulating paste containing lead borosilicate glass is printed, dried, and fired at 600 ° C.

(9) A large substrate is used as a terminal electrode 3 for each element region.
Primary division is performed in a strip shape so that the end faces on the a and 3b sides appear.

(10) Surface side electrode film 31 in each element region
The end surface side electrode films 33a and 33b are formed so that the a and 31b are connected to the back surface side electrode films 32a and 32b. Specifically, Ag-based conductive paste is printed and dried at 600 ° C.
Bake in.

(11) Two strip-shaped substrates are provided in each element area.
Next division is performed.

(12) Surface side electrode films 31a, 3 of each element
1b, back surface electrode films 32a and 32b, and end surface electrode film 33
Plating layers 34a and 34b are formed on the surfaces of a and 33b.

As described above, in the present invention, since the surface side electrode films 31a and 31b are composed of the lower layer 310 and the upper layer 311 for improving the surface smoothness, the resistance of the completed chip resistor 1 is improved. It is possible to suppress the occurrence of a step between the surface where the body film 4 is formed and the surface where the terminal electrodes 3a and 3b are formed, and the mounting reliability due to suction is greatly improved.

Since the upper layer 311 and the lower layer 310 are baked in the same step, the upper layer 311 and the lower layer 31 are substantially formed.
0 is integrated, the upper layer 311 can be stably bonded to the lower layer 310, and peeling between the upper layer 311 and the lower layer 310 does not occur at all.

Further, after the resistance value of the resistor film 4 is adjusted, only the heat treatment in the firing step of the insulating film, that is, the second insulating layer 52 in the embodiment, is performed. It is possible to minimize the variation in the resistance value of the film 4.

The inventor of the present invention has found that the mounting test by an automatic mounting machine by flattening the surface, the yield due to the variation of the resistance value after the resistance value adjustment, and the dummy electrode films 35a, 3 after the temperature cycle are performed.
5b or the bonding strength of the upper layer 311 was compared between the product of the present invention and the conventional product shown in FIG.

The mounting error in the mounting test by the automatic mounting machine was 0.01% in the present invention product and 0.03% in the conventional product. The resistance yield is 98% in the product of the present invention and 96 in the conventional product.
%Met. Further, the adhesive strength of the surface side electrode films 31a and 31b after the temperature cycle is 1.5 K in the product of the present invention.
g (minimum 0.8 Kg), 1.0 for conventional products
It was Kg (minimum 0.5 Kg).

That is, the mounting efficiency due to the flattening of the surface,
The present invention gave very good results in both the variation of the resistance value and the adhesive strength.

The above description is of a chip resistor. For example, in the case of a multiple resistor, a plurality of resistor films and terminal electrodes corresponding to the resistor films are formed per element. The pattern of the terminal electrode and the pattern of the resistor film may be controlled.

[0054]

As described above, according to the present invention, there is provided a method for manufacturing a fixed resistor which has excellent surface smoothness, minimizes fluctuations in resistance value, and prevents peeling of electrodes. Become.

[0055]

[Brief description of drawings]

FIG. 1 is a plan view of a chip resistor which is an example of a fixed resistor according to the present invention.

FIG. 2 is a vertical sectional view showing a section taken along line XX in FIG.

FIG. 3 is a vertical cross-sectional view explaining the main steps of manufacturing the chip resistor of the present invention.

FIG. 4 is a vertical sectional view of a conventional chip resistor.

[Explanation of symbols]

 1 ... Chip resistor 2 ... Insulating substrate 20 ... Large insulating substrate 21 ... Dividing groove 3a, 3b ... Terminal electrode 31a, 31b ... Surface side terminal electrode film 310 ... ...... Lower layer 311 ・ ・ ・ ・ Upper layer 32a, 32b ・ ・ ・ Back surface side terminal electrode film 33a, 33b ・ ・ ・ End surface side terminal electrode film 35a, 35b ・ ・ ・ Dummy electrode film 4 ... .... Resistor film 5 ... Insulating film 51 ... First insulating film 52 ... Second insulating film

Claims (1)

[Claims] 1. A pair of multi-layered terminal electrodes, a resistor film is formed between the pair of terminal electrodes, and an insulating film is formed on the resistor film, respectively, at opposite end portions of the rectangular substrate on the surface side. A method of manufacturing a fixed resistor comprising: a step of forming the terminal electrode by printing / baking a conductive paste a plurality of times; and a step of printing the resistor paste so that the resistor film is connected only to a lower layer of the terminal electrode. A method of manufacturing a fixed resistor, comprising: a step of forming by baking, and a step of forming an insulating film by printing and baking an insulating paste so as to cover the resistor film.