JP3012875B2 - Manufacturing method of chip resistor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip resistor in which a resistor is provided on a surface of a chip-shaped insulating substrate, and electrodes are formed on both ends of the substrate. And a method for producing the same. 2. Description of the Related Art Conventionally, the structure of the electrode of a chip resistor is formed by applying and firing a so-called metal glaze paste containing Ag-Pt or the like using glass as a binder. Further, as disclosed in Japanese Patent Publication No. 58-46161, an electrode made of metal glaze is encapsulated in an Ag-resin-based conductive paste in which Ag is mixed in a thermosetting resin, and is cured by heating. Some of them have electrodes formed. [0004] In the former case of the above-mentioned prior art, the Ag particles in the metal glaze alloy with the solder during soldering, so-called solder cracking occurs, and the solder strength decreases. In addition, there is a problem that the solder cannot be reattached. Further, in this case, since the electrodes are formed only when the resistor is provided, there is a problem that the strength of the fixing force when soldered to the circuit board is low. In the latter case of the above-mentioned prior art, the metal glaze electrode must be entirely covered with an Ag-resin paste, and coated so as to accurately include the electrode portion of an extremely small chip resistor. It's relatively difficult to do,
Since the entire electrode is covered with resin, there is a problem that the solder strength after soldering the electrode is weak. Further, when the resistor is trimmed, a trimming groove is formed. In this case, if the electrode is plated after the trimming, there arises a problem that the characteristics of the resistor are changed by the plating solution. Further, the trimming grooves are made of glass or resin.
When partially filled with rim material, a concave
Due to the formation of protrusions, printing failure occurs in later display printing
When mounting on a circuit board
Unevenness is formed on the suction surface when suction is performed using a suction nozzle
May cause mounting errors.
You. Also, cover the glass coat with a glass coat.
Although it is considered that when forming a further glass coat
There is a problem that the resistance value of the resistor changes due to the applied heat. Also
In glass paste due to high heat when forming glass coat
Of binder obtained by one firing because the binder of
The squat is thin enough to completely fill the trimming grooves.
To actually fill the trimming groove
Requires multiple layers of glass coating,
There are significant problems. Furthermore, glass coat
Glass on the resistor because it is weak and easily cracked
It is not sufficient as a protective layer of the coat. In addition, glass
Because TMG inflexible, to a multi-piece a chip resistor substrate
When the glass coat enters the dividing groove of the large substrate when
When the substrate is divided, the glass coat may
The problem is that the product yield is reduced.
You. The present invention has been made in view of the above-mentioned problems of the prior art, and is a chip resistor which is resistant to solder cracking, has a large fixing force when soldered to a circuit board, and can maintain the characteristics of the resistor. It is intended to provide a manufacturing method. According to the present invention, a metal glaze-based first electrode is formed on a surface of an insulating ceramic substrate by printing, and the first electrode is sandwiched between the first electrode and the back surface of the substrate. A step of printing and forming a metal glaze-based second electrode also at an opposing position; a step of printing and forming a resistor to which the first electrode is directly connected ;
And trimming the resistor.
And applying a resin coat on the glass coat.
And a step of applying a resin-containing silver paint on the side edge of the substrate on which the first and second electrodes and the resistor are formed in a substantially U-shape on the first and second electrodes on the front and back surfaces. forming a step of forming a third electrode subjected to heat treatment at a low temperature is applied to thickly directly to the state to be superimposed, the first, the Ni plating layer is subjected to Ni plating treatment on the outer surface of the second and third electrodes and the process you, the N
Apply solder plating on the i-plated layer
And a step of forming a plating layer in order.
Manufacture anti-arms . In the chip resistor manufactured by the method of the present invention, the first, second, and third electrodes provided on the front, back, and end surfaces of both ends of the insulating substrate are covered with Ni plating to prevent solder breakage. have improved solder wettability of the Ni plating layer was further solder plating process. On the lower surface side of the substrate,
Since the electrode is provided so as to partially overlap the second electrode, the electrode is formed in a stepped shape. When the chip resistor of the present invention is mounted on a printed circuit board, the electrode is formed between the lower surface of the electrode and the circuit board. Solder wraps around the gap, so that a sufficient fixing force can be obtained even if the chip resistor manufactured by the method of the present invention is small. Further, according to the method for manufacturing a chip resistor of the present invention,
The first front and back surfaces of the resin-containing silver paint on the side end portion including a rough sides of board, partially superimposed and applied to the second electrode, the third Ag- resin-based subjected to heat treatment at a low temperature Since the electrode is formed, the fixing force to the substrate is strong, and the third electrode has appropriate flexibility, so that a large mechanical strength can be obtained. In particular, since the resin coat is applied on the glass coat after trimming, the third electrode and the resin coat can effectively prevent the plating solution from penetrating in the plating step, and the electrodes and the resistor have defects such as peeling. And the characteristics of the resistor can be maintained. Also firing of resin paste
The binder is not lost due to the low temperature.
Because the thickness after firing is thicker than the glass coat,
Completely fill the trimming groove with one layer of resin coat
Can be. This protects the glass coat on the resistor
When forming a resin coat as a protective coat,
Protective coats are easier to form and lower manufacturing costs.
Can be. Resin is more flexible than glass
Therefore, it becomes a sufficient protective coat against the glass coat,
Glass cores are used both in the manufacturing process and in the mounting process.
Not only provides adequate protection for the
The groove is used to divide the chip resistor substrate from the board.
Even if part of the gin coat enters, resin
No large loss of resin, large resin coat
Yield is significantly reduced due to defects
And not. Further, as described above , since the firing temperature of the resin coat is considerably lower than the firing temperature of the glass coat, even if the resin coat is fired in a state where a part of the resin coat is in the trimming groove, the heat at the time of firing does not occur. The characteristics of the resistor do not change. An embodiment of the present invention will be described below with reference to the drawings. The chip resistor 1 manufactured in this embodiment is:
As shown in FIG. 1, a convex resistor 3 is formed by printing on the surface of a ceramic substrate 2, and electrodes 4 are provided at both ends. The resistor 3 is provided with a thickness of about 10 μm of ruthenium oxide, and a trimming groove 5 is formed upward from the bottom of the convex shape by laser or sand blast to trim the resistance value. The electrode 4 of the chip resistor 1 is connected to the resistor 3
Has a first electrode 6 directly connected thereto, and a second electrode 7 formed to face the first electrode 6 with the substrate 2 interposed therebetween,
The first and second electrodes 6 and 7 are made of Ag-Pd, Ag-Pt
Etc. are formed by printing a metal glaze paste. Further, a third electrode 8 made of an Ag-resin-based conductive paste in which Ag is mixed into xylene or epoxy phenol resin is provided on the end face of the substrate with the first and second electrodes 6 and 7 interposed therebetween. The electrode 8 includes first and second electrodes 6,
7 is provided so as to partially cover them, thereby achieving conduction between the two. Then, Ni plating 9 and solder plating 10 are applied to cover the entire first, second, and third electrodes. The surface of the resistor 3 is protected by a glass coat 11 and a resin coat 12. As shown in FIGS. 3A to 3F, the method of manufacturing the chip resistor is as follows.
A plurality of rows of metal glaze paste to be the first electrode 6 are printed at predetermined intervals with the third slit 14 interposed therebetween and fired at a temperature close to 900 ° C. Further, in the same manner, the second electrode 7
It is formed at a position facing the electrode 6. Next, as shown in FIG. 3B, the resistors 3 are printed and formed in a matrix on the ceramic plate 13 between the first electrodes 6 and fired at a temperature of 850 ° C. on average. Then, as shown in FIG. 3C, a glass coat 11 is applied to the surface of the resistor 3 and fired at an average temperature of 650 ° C. Thereafter, the ceramic plate 13 is cut (scribed) along slits 14 provided vertically and horizontally for each chip resistor, and as shown in FIG.
A third electrode 8 of a resin-based conductive paste is applied to a thickness of about 20 μ and cured at a temperature of about 200 ° C. Then, as shown in FIGS. 3E and 3F, Ni plating 9 and solder plating 10 are sequentially applied to the first, second, and third electrodes 6 and 6, respectively.
7 and 8 are coated. In this case, since the slits 14 are provided from both sides of the substrate, when the resin is applied to the end face of the ceramic substrate in a state of being partially overlapped, a good electrical and mechanical state can be obtained. According to this method, defects such as peeling of the terminal electrode and slack do not occur on the end face of the ceramic substrate. In addition, as shown in FIG. 1, the terminal electrode can be formed on the side end surface 5. The resistor 3 of each chip resistor is trimmed to adjust the resistance, and a resin coat 12 such as an epoxy resin is used.
And cured at a temperature around 200 ° C. Although FIG. 3 shows that trimming is performed after plating,
In the method of the present invention, the trimming is performed in the state of FIG. 3C before performing the plating process. Thereafter, a resin coat 12 is applied on the glass coat 11, and the steps shown in FIG. 3D and thereafter are performed. Thus, the resistance value is trimmed without separating the ceramic plate 13 for each chip, so that the trimming operation can be performed efficiently. In addition, since the trimming groove is covered with the resin coat 12, there is no adverse effect on the resistor during the subsequent plating operation. According to the chip resistor of this embodiment, the resistance of the electrode 4 to solder cracking is improved, and the metal substrate is made of only a metal glaze and is more flexible than the electrode with respect to bending of the circuit board. Strong because it is high. Also, since the first and second electrodes 6 and 7 are firmly soldered to the circuit board at the time of soldering, the first and second electrodes 6 and 7 are extremely strong.
The use of the Ag-resin as the third electrode does not cause a decrease in the fixing force. The resistor of the chip resistor of the present invention can be appropriately selected according to its use, such as a metal film resistor and a carbon film resistor. The components of the metal glaze paste and the Ag-resin-based conductive paste may contain other additives as appropriate. In the present application, the resistor is coated with a glass coat and trimmed, but can be appropriately changed by a known method, and can be similarly applied to a chip component using another resistor. It is not limited to one. In this chip resistor, an Ag-resin-based third electrode is provided on the end face of the substrate over the metal glaze-based first and second electrodes provided on both surfaces of the substrate, and the first, second, and third electrodes are provided. Since the Ni plating layer that covers the third electrode and the solder plating layer that covers the Ni plating layer are formed, they are resistant to solder cracking and can be reattached to the circuit board. Also, since the third electrode is provided so as to partially overlap the second electrode on the lower surface side of the substrate,
A step is formed by the electrode on the lower surface side of the substrate, and when soldered to the circuit board, the solder goes into the gap generated between the lower electrode and the circuit board, and a strong fixing force is obtained. In addition, since the Ag-resin-based third electrode provided on the end face of the substrate has appropriate flexibility, it can sufficiently withstand the bending of the circuit board. In the method for manufacturing a chip resistor according to the present invention,
The first front and back surfaces of the resin-containing silver paint base plate side end face,
Since the third electrode is formed by directly applying in a state of being partially superimposed on the second electrode and heat-treating at a low temperature to form the third electrode, the third electrode is directly bonded to the rough cross section of the substrate as it is cut, and the adhesive force of the third electrode is reduced strong. Further, when plating the electrode for soldering, the third electrode can effectively prevent the penetration of the plating solution, and a high quality product can be manufactured without causing defects such as peeling or cracking of the electrode. Therefore, chip resistors have been reduced in size due to today's demand for higher packaging density, but sufficient adhesion can be obtained even with small electrodes, making electrical products smaller and lighter and more reliable.
It greatly contributes to improvement of durability and productivity. According to the present invention, after trimming, the glass
Since a resin coat is applied on the coat,
Resin coating effectively prevents plating solution penetration
To prevent defects such as peeling from the electrodes and resistors.
The characteristics of the resistor can be maintained. Also firing of resin paste
The binder is not lost due to the low temperature.
Because the thickness after firing is thicker than the glass coat,
Completely filling that the trimming grooves in the resin coating of the first layer
Can be. This protects the glass coat on the resistor
When forming a resin coat as a protective coat,
Protective coats are easier to form and lower manufacturing costs.
Can be. Resin is more flexible than glass
Therefore, it becomes a sufficient protective coat against the glass coat,
Glass cores are used both in the manufacturing process and in the mounting process.
Not only provides adequate protection for the
The groove is used to divide the chip resistor substrate from the board.
Even if part of the gin coat enters, resin
No large loss of resin, large resin coat
Yield is significantly reduced due to defects
And not. Furthermore, as mentioned above, the firing temperature of the resin coat is
Because it is considerably lower than the firing temperature of the glass coat,
Resinco with part of the coating in the trimming groove
Even when firing the sheet, the heat of firing changes the characteristics of the resistor
There is the advantage of not having to.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of one embodiment of a chip resistor manufactured by the method of the present invention. FIG. 2 is a sectional view taken along line AA of FIG. FIG. 3 (A), (B), (C), (D), (E),
(F) is a longitudinal sectional view showing the manufacturing process of the chip resistor of the present invention. [Description of Signs] 1 Chip resistor 2 Substrate 3 Resistor 4 Electrode 5 Trimming groove 6 First electrode 7 Second electrode 8 Third electrode 9 Ni plating 10 Solder plating 11 Glass coat 12 Resin coat 13 Ceramic plate 14 Slit

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yozo Ohara 3158 Shimo-Okubo, Osawano-cho, Kamishinkawa-gun, Toyama Pref. Hokuriku Electric Industry Co., Ltd. 61-268001 (JP, A) JP-A-57-184202 (JP, A) JP-A-55-99701 (JP, A) JP-A-55-120101 (JP, A) U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01C 7/00 H01C 17/00-17/28

Claims (1)

(57) [Claims] A step of printing and forming a metal glaze-based first electrode on the surface of the insulating ceramic substrate; and a step of printing and forming a metal glaze-based second electrode also at a position on the back surface of the substrate facing the first electrode with the substrate interposed therebetween. A step of printing and forming a resistor to which the first electrode is directly connected ;
Coating with a glass coat ; and
Trimming and registering on the glass coat
And applying a resin-containing silver paint on the side edges of the substrate on which the first and second electrodes and the resistor are formed in a substantially U-shape on the first and second electrodes on the front and back surfaces. outer surface of forming a third electrode by applying a thick directly in a state of partially superimposed heat treatment at a low temperature, the first, second and third electrodes
A step that form a Ni plating layer is subjected to Ni plating above, further solder plating on the Ni plating layer
And forming a solder plating layer in order
Method of manufacturing a chip resistor you characterized by producing the chip resistor to.