JPH08203713A - Manufacture of square with film chip resistor - Google Patents

Abstract

PURPOSE: To provide a low cost and high reliability square thin film chip resistor which is generally used for an electronic circuit. CONSTITUTION: A pair of thin film top electrode layer 2 is formed on a main surface of a square-shaped 96% alumina board 1. A thin film resistor layer 4 is formed between thin film electrode layers so that it may be partially placed on the paired thin film top electrode layers 2, thereby forming a resin protective film layer 5 so that the thin film resistor layer 4 may be covered to a satisfactory extent while a conductor resin top electrode layer 6 is formed so that it may cover the thin film resistor layer 4 of the paired thin film top electrode layer 2 and be partially placed on both ends of the resin protective film layer 5. After the formation of the resin protective film layer 5, a pair of conductor resin rear surface electrode layer 3 are formed on the rear surface of the alumina board 1, thereby forming a pair of thin film end face electrode layers 7 on both ends of the 96% alumina board 1 so that it may be placed on the conductor resin top electrode layer 6 and the conductor resin rear surface electrode layer 3 respectively and forming an electrode plating layer 8 on the exposed electrode part.

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 rectangular thin film chip resistor generally used in electronic circuits.

[0002]

2. Description of the Related Art In recent years, with the downsizing of electronic equipment, there is an increasing demand for miniaturization of electronic components to be mounted in order to increase the packaging density of the circuit board. Along with the miniaturization of the rectangular chip resistors, there is an increasing demand for rectangular thin film chip resistors with high accuracy (resistance tolerance, resistance temperature characteristics) and excellent current noise characteristics.

The structure of a conventional rectangular thin film chip resistor is shown in FIG.
4 is a sectional view and a manufacturing method thereof is shown in the process drawing of FIG.

Referring to FIG. 3, a conventional rectangular thin film chip resistor is composed of a pair of thin film upper surface electrode layers 12 made of Au formed at the end portions on the front surface of a square 96% alumina substrate 11 and at the end portions on the back surface. A pair of thin film back surface electrode layers 13 also formed of Au, and a thin film resistor layer 14 formed of a Ni—Cr alloy that covers the pair of thin film top surface electrode layers 12 and is formed between the thin film top surface electrode layers 12. This thin film resistor layer 14
A pair of epoxy resin protective film layers 15 that completely cover the resin protective film layer 15 and a pair of thin film resistor layers 14 that are exposed on the pair of thin film upper surface electrode layers 12 and that overlap a part of both ends of the resin protective film layer 15. The conductive resin upper surface electrode layer 16 and the conductive resin upper surface electrode layer 16 and the thin film rear surface electrode layer 13 are connected by 96%.
It is composed of a pair of thin film end face electrode layers 17 formed on both ends of the alumina substrate 11 and an electrode plating layer 18 formed on the exposed electrode portions by nickel and solder.

Next, the manufacturing process of the conventional rectangular thin film chip resistor will be described with reference to FIG. First, the insulating substrate 11 made of 96% alumina is prepared. Next, after screen-printing and drying an electrode paste made of a metal organic compound containing Au as a main component on the front and back surfaces of the 96% alumina substrate 11,
In order to remove only the organic component of the metal organic electrode paste and burn only the metal component onto the alumina substrate 11, the thin film upper surface electrode layer 12 is fired in a belt-type continuous firing furnace.
And a step of forming the thin film rear surface electrode layer 13 is performed.

Next, Ni- is formed on the entire surface of the insulating substrate 11.
A photolithography process step (resist application / drying, for performing a sputtering step for forming the thin film resistor layer 14 of Cr or the like, and forming the thin film resistor layer into a predetermined resistance pattern 14a
Exposure to light, development, etching, and resist stripping) to form a stable film for the resistance pattern 14a.
A heat treatment process in a 0 ° C. atmosphere is performed.

After that, a laser resistance trimming process is performed by laser trimming to correct the resistance value of the resistance pattern to a predetermined value.

Next, the resistance value-corrected resistance pattern 14b
In order to protect the resin, a step of forming the resin protective film layer 15 with a thermosetting resin is performed. Next, a thermosetting conductive resin is used to cover the resistance-value-corrected resistance pattern 14b not covered with the resin protective film layer 15 on the thin film upper surface electrode layer 12 and to overlap both ends of the resin protective film layer 15. A step of forming the formed conductor resin upper surface electrode layer 16 is performed.

Next, an end face electrode forming step of forming the thin film end face electrode layer 17 is performed by using sputtering on the end face of the insulating substrate 11.

Finally, an electrode plating step of forming an electrode plating layer 18 on the exposed electrode portion for ensuring reliability during soldering was performed to form a rectangular thin film chip resistor.

[0011]

However, in the conventional method of manufacturing a thin film chip resistor, the back electrode material is limited because the resistor is formed after the back electrode is formed. That is, in the etching performed in the photolithography process step of forming the resistor pattern, since it is immersed in an etching solution (strongly acidic), a gold-based thin film electrode that is not immersed in the etching solution as in the conventional example is used, or copper, The back electrode layer was formed by patterning a nichrome thin film electrode by a photolithography process after forming by sputtering. Therefore, when gold is used, the equipment cost is not expensive, but the material cost is high, and when copper or nichrome is used, the equipment cost and man-hours are high, and it is difficult to reduce the manufacturing cost. There were challenges.

In order to solve the above problems, it is an object of the present invention to provide an inexpensive rectangular thin film chip resistor.

[0013]

In order to achieve the above object, a method for manufacturing a rectangular thin film chip resistor according to the present invention comprises a step of forming a pair of thin film upper surface electrode layers on a main surface of a rectangular insulating substrate, A step of forming a thin film resistor layer on each of the pair of thin film upper surface electrode layers and between the thin film upper surface electrode layers on the main surface of the insulating substrate; and a resin protective film layer that completely covers the thin film resistor layer. A step of forming, a step of forming a pair of conductor resin upper surface electrode layers that cover the pair of thin film upper surface electrode layers and overlap a part of both ends of the resin protective film layer, and a pair of conductors on the back surface of the insulating substrate. A step of forming a resin back surface electrode layer, a step of forming a pair of thin film end surface electrode layers so as to be connected to the conductor resin top surface electrode layer and the conductor resin back surface electrode layer at both ends of the insulating substrate, and the exposed conductor Resin upper electrode layer And a step of forming an electrode plating layer so as to cover the conductor resin back surface electrode layer and the thin film end surface electrode layer, wherein the conductor resin back surface electrode layer is formed after forming the thin film resistor layer. It is what

[0014]

According to the present invention, since the back electrode is formed after the resistor is formed, the back electrode is dipped in the etching solution (strongly acidic) by the etching treatment performed in the photolithography process step of the resistor pattern formation. Because there is nothing
The back electrode material is not limited. Therefore, since the back electrode can be formed by the conventional screen printing method using the commonly used conductive resin silver paste, it is possible to reduce the material cost, the man-hour and the equipment cost, and the inexpensive rectangular thin film. A chip resistor can be realized.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A prismatic thin film chip resistor and a method of manufacturing the same according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a prismatic thin film chip resistor according to an embodiment of the present invention, and FIG. 2 is a process diagram showing a manufacturing method thereof.

First, the structure of the product will be described with reference to FIG.
1, a pair of thin film upper surface electrode layers 2 made of Au formed on the surface of a square 96% alumina substrate 1 and a pair of conductor resin back surface electrodes made of a thick film conductive resin containing silver as a conductive component formed on the back surface. Ni-C formed between the layer 3 and the pair of thin film upper surface electrode layers 2 and between the thin film upper surface electrode layers 2.
The thin film resistor layer 4 made of an r alloy, the epoxy resin protective film layer 5 that completely covers the thin film resistor layer 4, and the thin film resistor layer 4 that is exposed on the pair of thin film upper surface electrode layers 2 and protects the resin. A pair of conductor resin upper surface electrode layers 6 formed so as to overlap a part of both ends of the film layer 5, and both end portions of the 96% alumina substrate 1 so as to connect the conductor resin upper surface electrode layer 6 and the conductor resin rear surface electrode layer 3 to each other. A pair of thin film end face electrode layers 7 respectively formed on the
And an electrode plating layer 8 of nickel and solder formed on the exposed electrode layer among the above electrode layers.

Next, the manufacturing method will be described with reference to FIG. First, step A of preparing a 96% alumina substrate 1 having excellent heat resistance and insulating properties is performed. Next, in order to screen-print and dry an electrode paste made of a metal organic material containing Au as a main component on the surface of the 96% alumina substrate 1, the organic component is removed and only the metal component is baked on the 96% alumina substrate 1. A step B of forming the thin film upper surface electrode layer 2 is performed by baking in a belt type continuous baking furnace at a temperature of 850 ° C. at a peak time of 6 minutes and an IN-OUT time of 45 minutes.

Next, Ni--Cr was formed on the 96% alumina substrate 1.
Photolithographic process step D (resist application / drying, exposure, development, etching, resist peeling) of forming the thin film resistor layer 4 into a predetermined resistance pattern 4a is performed through the sputtering step C of forming the thin film resistor layer 4 of FIG. In order to make the resistance pattern 4a a stable film, a heat treatment step E is performed in a temperature atmosphere of 350 to 400 ° C.

Thereafter, in order to correct the resistance value of the resistance pattern 4a to a predetermined value, a resistance value correction step F by laser trimming is performed.

Next, in order to protect the resistance pattern 4b whose resistance value has been corrected, a resin paste is screen-printed and 2
A step G of forming the resin protective film layer 5 by thermosetting with a profile of 00 ° C. for 30 minutes is performed.

Next, not covered with the resin protective film layer 5,
Resistor pattern 4 whose resistance value has been corrected on the thin film upper surface electrode layer 2
Conductive resin paste containing silver as a conductive metal material is screen-printed so as to cover b and overlap a part of both ends of the resin protective film layer 5, and is thermally cured at a profile of 200 ° C. for 30 minutes to form a conductor. Step H of forming the resin upper surface electrode layer 6 is performed.

Next, a conductive resin paste containing silver as a conductive metal material is screen-printed on the back surface of the 96% alumina substrate at a position facing the conductive resin upper surface electrode layer 6, and 2
A step I of forming the conductor resin back surface electrode layer 3 by thermosetting with a profile of 00 ° C. for 30 minutes is performed. Thus, by forming the conductor resin back surface electrode layer 3 after forming the resin protective film layer 5, it is possible to prevent the thin film resistor layer 4 from being soiled or damaged by the conductive resin paste or the like. In the present embodiment, since the conductor resin back surface electrode is formed as the back surface electrode after the resistor is formed, the back surface electrode material is not limited because the resistance to etching liquid does not matter, and therefore the conventional screen printing method is used. Since the conductor resin silver paste that has been generally used can be used, the material cost, the equipment cost, and the man-hour can be reduced.

Next, an end face electrode forming step J for forming the Ni—Cr based thin film end face electrode layer 7 on the end face of the 96% alumina substrate 1 by sputtering is performed.

Finally, in order to prevent electrode erosion during soldering of the exposed conductor resin rear surface electrode layer 3, conductor resin upper surface electrode layer 6 and thin film end surface electrode layer 7 and to secure reliability during soldering. , Ni and Sn-P by electroplating
Electrode plating step K for forming the electrode plating layer 8 of b
I do.

Through the above steps, the rectangular thin film chip resistor according to the present embodiment was prototyped. When the rectangular thin film chip resistor of this example and the conventional rectangular thin film chip resistor were compared, the electrode strength was the same.

In this embodiment, the conductor resin electrode layer is formed of a silver-based resin material. However, the conductive resin electrode layer is not limited to a silver-based material, and a material that can be used as an electrode material such as copper or gold is used. It goes without saying that the same effect can be obtained in all cases.

Further, in this embodiment, the conductor resin back surface electrode layer is formed after the conductor resin top surface electrode layer, but the order of this step may be either first.

[0029]

As described above, according to the present invention, since the back electrode is formed after the resistor is formed, the back electrode material is not limited. Therefore, the following effects (1) and (2) can be obtained, and the prismatic thin film chip resistor can be realized at low cost.

(1) Since it can be formed by the screen printing method, the equipment cost and the number of steps can be reduced as compared with the photolithography method (sputtering, exposure, development, etching).

(2) Since the conductor resin silver paste which is usually used in a large amount can be used, the material cost can be reduced. Moreover, since the back electrode layer is formed by curing the paste after printing at about 200 ° C., it is possible to reduce power consumption as compared with conventional high temperature firing (about 850 ° C.).

In addition, since the back electrode is formed of a thin film in the past, when the substrate was first divided in a zigzag pattern, chipping occurred on the back electrode near the dividing slits. Since it is formed of the conductor resin electrode layer, it is possible to have a function of absorbing shock due to contact with the dividing jig at the time of the primary division, and it is possible to prevent chipping of the back surface electrode and to provide a highly reliable rectangular thin film. A chip resistor can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a prismatic thin film chip resistor according to an embodiment of the present invention.

FIG. 2 is a process diagram showing a method for manufacturing a conformal thin film chip resistor.

FIG. 3 is a sectional view showing the structure of a conventional rectangular thin film chip resistor.

FIG. 4 is a process diagram showing a method for manufacturing a conformal thin film chip resistor.

[Explanation of symbols]

 1 96% alumina substrate 2 thin film upper surface electrode layer 3 conductor resin rear surface electrode layer 4 thin film resistor layer 5 resin protective film layer 6 conductor resin upper surface electrode layer 7 thin film end surface electrode layer 8 electrode plating layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01C 17/242

Claims (2)

[Claims] 1. A step of forming a pair of thin film upper surface electrode layers on a main surface of a rectangular insulating substrate, and the thin film upper surface electrode overlapping each of the pair of thin film upper surface electrode layers and on the main surface of the insulating substrate. A step of forming a thin film resistor layer between the layers, a step of forming a resin protective film layer that completely covers the thin film resistor layer, and a step of covering the pair of thin film upper surface electrode layers and at both ends of the resin protective film layer. Forming a pair of conductor resin upper surface electrode layers overlapping the portion, a step of forming a pair of conductor resin back surface electrode layers on the back surface of the insulating substrate, the conductor resin upper surface electrode layer and the A step of forming a pair of thin film end face electrode layers so as to connect with the conductor resin back face electrode layer, and an electrode plating layer so as to cover the exposed conductor resin top face electrode layer, the conductor resin back face electrode layer and the thin film end face electrode layer To form And a step of forming the conductive resin back surface electrode layer after forming the thin film resistor layer. 2. The method for manufacturing a rectangular thin film chip resistor according to claim 1, wherein the conductor resin back surface electrode layer is formed after the resin protective film layer covering the thin film resistor layer is formed.