JPH05243073A - Chip-like electronic parts and method for forming its terminal electrode - Google Patents

Abstract

PURPOSE:To prevent the Manhattan phenomenon when chip-like electronic parts for surface mounting are soldered. CONSTITUTION:The terminal electrode of a chip-like electronic parts is formed out of the end surface of the electronic parts and the peripheral surface of the end section of the electronic parts, which follows the end surface. The end surface is made of a metallic layer 2 unwet with solder, which is hard to be wet with solder, and the peripheral surface of the end section is made of a metallic layer 3 wet with solder, which is easy to be wet with solder. Thereby, since the fused solder does not wet the metallic layer 2 and is not stuck on it, the end surface of the chip-like electronic parts is not stretched by the solder, and the Manhattan phenomenon can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip-shaped electronic component such as a multilayer capacitor and a chip resistor which are surface-mounted on a printed circuit board, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Chip-shaped electronic components such as multilayer capacitors and chip-shaped resistors are often produced as surface-mounted electronic components on a printed circuit board. A multilayer capacitor is formed by forming internal electrode coatings on each of a plurality of green sheets of ceramic material made of metal oxide so that the ends of the respective green sheets are alternately drawn out in opposite directions. The formed green sheets are laminated and baked to form a capacitor element body, and terminal electrodes are formed on both ends thereof. The chip resistor is a resistor body obtained by forming a resistor film such as a metal film on a ceramic body and forming a protective coating film on the surface thereof, and forming terminal electrodes at both ends of the resistor body. ..

In order to form a terminal electrode not only on these multilayer capacitors and chip resistors but also on other chip-shaped electronic parts, conductive metal powder such as Ag, Ag-Pd, and Zn is made of resin and other components in advance. An electrode material paste obtained by mixing with a non-aqueous solvent is applied to a flat surface to a thickness of 1 mm or less, and a coating layer is prepared. By alternately dipping both ends, the electrode material paste is attached to these both ends, and then dried and baked.

The chip-shaped electronic component obtained in this way has been made smaller and lighter as electronic equipment has become smaller and lighter. Therefore, soldering lands spaced apart from each other for surface mounting on a printed circuit board are used. When soldering the terminal electrodes on both ends of this component, the action on the terminal electrodes on both sides due to the molten solder supplied is subtly different due to the difference in the shape of the terminal electrodes on both sides. In the case of, the part is pulled to one soldering land side and the other stands up, called chip standing,
The so-called Manhattan phenomenon may occur. This phenomenon is a phenomenon that occurs when the end surface of the chip component gets wet with the molten solder supplied to the soldering land and the solder adheres to it.As described above, the multilayer capacitor has internal electrode end portions on both end surfaces. Since it is led out, it is inevitable to form the terminal electrode on this end face.
To prevent the phenomenon of chip standing, control the amount of solder so that more solder is not supplied than before, and devise the shape of the soldering land on the printed circuit board to prevent a large amount of molten solder from being supplied to the end surface of the terminal electrode. I was doing

[0005]

However, when controlling the amount of solder, it is effective in the case of so-called reflow soldering in which solder paste is applied and then heated to melt the solder powder, that is, so-called reflow soldering. However, even in this case, as the chip component becomes smaller, the amount of solder to be controlled becomes delicate, and it becomes gradually difficult to prevent the chip from standing. Also, in the case of so-called flow soldering, in which molten solder is ejected and the soldering part is brought into contact with the top of it, so-called flow soldering cannot be performed delicately, so avoiding chip standing I couldn't.

Further, in order to prevent the phenomenon of chip standing by devising the land shape of the printed circuit board, the wiring pattern of the printed circuit board is restricted and the performance of the printed circuit board is deteriorated. There is a problem that is not enough.

It is an object of the present invention to prevent the phenomenon of chip standing that occurs when soldering when mounting a chip-shaped electronic component on the surface of a printed circuit board.

[0008]

In order to solve the above-mentioned problems, the present invention provides a chip-shaped electronic component having terminal electrodes on both side ends of the chip-shaped electronic component body. Melt that does not wet with molten solder is provided on the end surface and the peripheral surfaces on both sides following it, and the solder non-wetting metal layer is connected to the peripheral surface on both ends of the chip-shaped electronic component element body. Provided is a chip-shaped electronic component provided with a solder-wetting metal layer that is well wetted with solder.

Further, the present invention includes an electrode coating film forming step of forming an electrode coating film by immersing both end portions of a chip-shaped electronic component body in an electrode material paste so that the terminal electrode of the chip electronic component is formed. In the method for forming the above, the electrode coating film forming step is to immerse both side end surfaces of the chip-shaped electronic component element body and the peripheral surfaces on both side end portions subsequent thereto in an electrode material paste containing a metal poorly wetted by molten solder. The first electrode coating film forming step of forming an electrode coating film by the method and connecting to the electrode coating film on the peripheral surfaces of both end portions of the chip-shaped electronic component element body formed by the first electrode coating film forming step The method for forming a terminal electrode of a chip-shaped electronic component according to claim 1, further comprising a second electrode coating film forming step of forming an electrode coating film by applying an electrode material paste containing a metal having good wettability. That.

[0010]

[Function] A solder non-wetting metal layer having poor wettability of molten solder is formed on both end surfaces of the chip electronic component body, and the solder non-wetting metal layer is connected to the peripheral surfaces of both end portions of the chip electronic component body. Since a solder-wetting metal layer with good wettability is formed on the molten solder, both are well soldered by placing the solder-wetting metal layer on the soldering land of the printed board and soldering, but the solder-non-wetting metal layer Since the molten solder does not get wet, it is possible to prevent the molten solder from sticking to it. If molten solder does not adhere to the end face of the chip-shaped electronic component element body, the end face is not pulled by the surface tension of the molten solder, so that the phenomenon of chip standing can be prevented.

[0011]

EXAMPLES Next, examples of the present invention will be described. Example 1 A ceramic slurry composed of a ceramic material such as a metal oxide and a binder was mixed with polyethylene terephthalate (P
A plurality of ceramic green sheets are prepared by a method of coating on a flat surface such as an ET film), and an electrode material paste made of Pd powder, a binder, etc. is applied to this to form a large number of internal electrode coating films at regular intervals. .. Then, the green sheets on which the internal electrode coating films are formed are sequentially stacked so that the ceramic green sheets are sandwiched between the internal electrode coating films, and then the stacked internal electrodes are cut. At this time, only one end of the coating film of the internal electrode is alternately led out to the opposite end face. The individual rectangular parallelepiped laminate thus obtained is fired to obtain a length of 1.6 mm and a width of 0.8 m.
m multilayer capacitor element body was produced.

Zn powder is contained as a metal material, and in addition, a binder and an organic solvent are contained.
Viscosity using terpineol 100 poise (25 °
The electrode material paste of C) is applied on a smooth plate to a thickness of 0.4 mm, one end surface and the peripheral surface of the above-mentioned laminated capacitor element body is immersed so as to be perpendicular to the application layer, and the electrode material paste is slowly pulled up. It was Then, it was dried at 150 ° C. for 20 minutes and then baked. In this way, the solder non-wetting metal layer was formed. Similarly, the other end of the multilayer capacitor body was subjected to the above treatment. Then Ag instead of Zn
Containing the powder of as an electrode material, otherwise the electrode material paste prepared in the same manner as above is applied by a coater onto the non-wetting metal layer formed on the peripheral surface of one end of the multilayer capacitor element body, Similarly dried and baked to form a strip of solder wet metal layer. Similarly, the other end of the multilayer capacitor body was subjected to the above treatment. In this way, as shown in FIG. 1, a chip-shaped multilayer capacitor in which terminal electrodes composed of the solder-non-wetting metal layers 2 and 2 and the band-shaped solder-wetting metal layers 3 and 3 are formed on both ends of the multilayer capacitor body 1 is obtained. Was obtained. As shown in FIG. 2, this chip-shaped multilayer capacitor has solder lands 5 and 5 of a printed circuit board 4 coated with solder paste, and the solder-wetting metal layers 3 and 3 are placed on the coating layer and heated. Reflow soldering may be performed by melting the solder by melting the solder, or may be temporarily fixed to the printed board 4 with an adhesive or the like, and between the solder-wetting metal layers 3 and 3 and the soldering lands 5 and 5. Alternatively, flow soldering may be performed in which a jet solder is brought into contact with the solder. 6 is solder when soldered.

100 chip-type multilayer capacitors were manufactured as described above. 1mm x 1 of this chip-type multilayer capacitor on a soldering land consisting of a pair of copper foils
It was placed on a solder paste coating layer obtained by printing a solder paste in an area of mm, heated at 240 ° C. for 10 seconds, and reflow soldering was performed. This was carried out for 100 chip-shaped multilayer capacitors, and the number of chip standings was counted, and the results are shown in Table 1.

Example 2 A solder non-wetting metal layer was formed in the same manner as in Example 1 except that Al powder was contained as an electrode material instead of Zn powder, and the solder non-wetting metal layer was formed in the same manner. Table 1 shows the results of the chip-shaped multilayer capacitors produced and tested for 100 of them in the same manner as in Example 1.

Example 3 The same procedure as in Example 1 was repeated except that the Pd powder was used as the electrode material instead of the Zn powder, and the same electrode material paste was used to form the solder non-wetting metal layer. Table 1 shows the results of the chip-shaped multilayer capacitors produced and tested for 100 of them in the same manner as in Example 1.

Example 4 Instead of Zn powder, Ag--Pd (Ag: Pd = 10:
90 alloy) powder was included as an electrode material, and a chip-shaped multilayer capacitor was prepared in the same manner as in Example 1 except that the same solder material layer was formed using the same electrode material paste as in Example 1. Table 1 shows the results of testing 100 pieces in the same manner as in Example 1.

Comparative Example 1 An electrode material paste similar to that of Example 1 was used except that Ag powder was contained as an electrode material instead of Zn powder, and solder was applied to both ends of the multilayer capacitor body. Table 1 shows the results of the same procedure as in Example 1 in which 100 chip-type multilayer capacitors having wet metal layers were prepared and tested.

[0018]

[Table 1]

In addition to the above, In and Ga are also examples of the electrode material used when forming the solder non-wetting metal layer.
One or more alloys or mixtures of the group including In and Ga and those shown in the above embodiment can be used, and these are well wetted by molten solder such as Ag and Cu. Further, it can be used by adding it to an electrode material having good solderability until the wetness of the molten solder is deteriorated as a whole and the solderability is sufficiently lowered. In addition to Ag and Cu described above, Au can also be used as an electrode material having good wettability with molten solder and good solderability.

[0020]

According to the present invention, the terminal electrode of the chip-shaped electronic component is connected to the solder non-wetting metal layer formed on the end face and the end peripheral surface subsequent thereto and the non-wetting metal layer on the end peripheral surface. Since it is composed of a solder-wetting metal layer that is well wetted by molten solder, when chip-shaped electronic components are surface-mounted on a printed circuit board, the terminal electrodes on both ends of this electronic component are reflow-soldered or flow-soldered onto the soldering lands of the printed circuit board. Even when soldering such as, etc., the molten solder does not get wet to the terminal electrodes on the end surface of the chip-shaped electronic component, so the molten solder does not stick here and this component cannot be pulled to either end The phenomenon of standing can be prevented. On the other hand, since the solder-wetting metal layer is well soldered to the soldering land, by connecting this solder-wetting metal layer and the solder-non-wetting metal layer, for example, a terminal electrode such as a chip-shaped multilayer capacitor is attached to the end surface. Even in such a case, the connection with the external circuit can be secured. In this way, it is not necessary to control the amount of solder or devise the land shape of the printed circuit board, which has been conventionally performed as a measure for preventing the chip rising phenomenon, and it is possible to improve the productivity and reduce the cost. ..

[Brief description of drawings]

FIG. 1 is a front view of a chip-shaped multilayer capacitor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a mounted state of the chip multilayer capacitor of the above embodiment.

[Explanation of symbols]

 1 ... ・ Multilayer capacitor element body 2, 2 ・ ・ Solder non-wetting metal layer 3, 3 ・ ・ Solder wetting metal layer

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical display location H01G 13/00 391 B 9174-5E (72) Inventor Yoichi Mizuno 6-16-20 Ueno Taito-ku, Tokyo Ueno Dielectric Co., Ltd.

Claims (2)

[Claims] 1. A chip-shaped electronic component having terminal electrodes on both side ends of the chip-shaped electronic component body, wherein both side end faces of the chip-shaped electronic component body and peripheral surfaces of both side end portions subsequent thereto are wetted with molten solder. A chip-shaped electronic component provided with a bad solder-wettable metal layer and a molten solder that is connected to the solder-non-wettable metal layer and a solder-wettable metal layer with good wetting on the peripheral surfaces of both ends of the chip-shaped electronic component body. .. 2. A method of forming a terminal electrode of a chip-shaped electronic component by having an electrode coating film forming step of forming an electrode coating film by immersing both end portions of the chip-shaped electronic component body in an electrode material paste. In the step of forming the electrode coating film, the electrode coating film is formed by immersing both side end faces of the chip-shaped electronic component element body and the peripheral faces of both side end portions subsequent thereto in an electrode material paste containing a metal that is poorly wetted by molten solder. A first electrode coating film forming step for forming a metal and a metal having good wettability connected to the electrode coating film on the peripheral surfaces of both end portions of the chip-shaped electronic component element body formed by the first electrode coating film forming step The method for forming a terminal electrode of a chip-shaped electronic component according to claim 1, further comprising a second electrode coating film forming step of forming an electrode coating film by applying an electrode material paste containing