JPH05243074A - Chip-like electronic parts and method for forming terminal electrode thereof - Google Patents

Abstract

PURPOSE:To prevent the Manhattan phenomenon when chip-like electronic parts for surface mounting are soldered. CONSTITUTION:On the end surface and the peripheral surface of the end section of a chip-like electronic parts, a metallic layer 2 wet with solder, which is easy to be wet with solder, is formed. On a section of the metallic layer 2 wet with solder, which exists on the end surface, a metallic layer 3 unwet with solder, which is hard to be wet with solder, is formed. Thus, the terminal electrode of the chip-like electronic parts, which comprises the metallic layers 2, 3, is formed. Thereby, since the fused solder does not wet the metallic layer 3 and is not stuck on it, the end surface of the chip-like electronic parts in 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 forming an electrode coating film thereof.

[0002]

2. Description of the Related Art Chip-shaped electronic components such as multilayer capacitors and TIFF resistors are often produced as electronic components surface-mounted 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.
In order to prevent the chip rising phenomenon, the amount of solder is controlled so that a large amount of solder is not supplied in the past,
The shape of the soldering land of the printed circuit board has been devised so that a large amount of molten solder is not supplied to the end surface of the terminal electrode.

[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 Manhattan phenomenon 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. The problem is that is not enough.

An object of the present invention is to prevent the phenomenon of chip standing that occurs during soldering when surface mounting a chip-shaped electronic component on 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. A solder-wetting metal layer that wets well with molten solder is provided on the end face and the peripheral surfaces on both sides following it, and the solder-wet metal layer on both end faces of the chip-shaped electronic component element does not wet the molten solder. A chip-shaped electronic component provided with a wet metal layer is provided.

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 of both side end portions subsequent thereto in an electrode material paste containing a metal that is well wetted by molten solder. The first electrode coating film forming step of forming an electrode coating film by the method and the poor wettability with the molten solder on the electrode coating film on both side end surfaces of the chip-shaped electronic component element body formed by the first electrode coating film forming step A method of forming a terminal electrode for a chip-shaped electronic component according to claim 1, further comprising a second electrode coating film forming step of forming an electrode material paste coating film containing a metal.

[0010]

[Function] A solder-wetting metal layer having good wettability to molten solder is continuously formed on both end faces and peripheral surfaces of the chip-shaped electronic component body, and the solder-wet metal layer on both end faces of the chip-shaped electronic component body is formed. Since a solder non-wetting metal layer with poor wettability to the molten solder is formed on top, both are well soldered by placing the solder wet metal layer on the soldering land of the printed circuit board and soldering, but solder non-wetting Since the molten solder does not get wet on the metal layer, the molten solder can be prevented from adhering 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 applying them to a flat surface such as an ET film), and an electrode material paste composed of Pd powder, 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.

It contains Ag powder as an electrode material, and also contains a binder and an organic solvent.
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, a solder-wet metal layer was formed. Similarly, the other end of the multilayer capacitor body was subjected to the above treatment. Then, an electrode material paste containing Zn powder as an electrode material instead of Ag and otherwise manufactured in the same manner as above was applied to the coating layer obtained by the same operation as above to form one end face of the above multilayer capacitor body. The surface of the formed wet metal layer was dipped, dried in the same manner as above, and baked to form a solder non-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 made of solder-wettable metal layers 2 and 2 and solder-unwettable metal layers 3 and 3 are formed on both ends of the multilayer capacitor body 1 as shown in FIG. Is obtained. As shown in FIG. 2, in this chip-shaped multilayer capacitor, a solder paste is applied to soldering lands 5 and 5 of a printed circuit board 4, and the solder-wetting metal layers 2 and 2 are placed on the applied 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 the solder-wetting metal layers 2 and 2 and the soldering lands 5 and 5 may be formed. It is also possible to perform flow soldering in which jet solder is brought into contact with and soldered. 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
Place on the solder paste coating layer printed on the area of mm
Reflow soldering was performed by heating at 40 ° C for 10 seconds. 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 The same procedure as in Example 1 was repeated except that an In powder was used as an electrode material instead of the Zn powder to form a 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 3 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 In the same manner as in Example 1, except that the non-wetting metal layer was not provided, a chip-shaped multilayer capacitor was prepared in which solder-wetting metal layers were formed on both ends of the multilayer capacitor element body, and 100 of them were manufactured. Table 1 shows the results of the same tests as in Example 1.
Shown in.

[0018]

[Table 1]

In addition to the above, Pd 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 Pd and Ga and those shown in the above examples can be used, and these are well wetted by molten solder such as Ag and Cu. It can also 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 is also an example of a metal material that has good wettability with molten solder and has good solderability.

[0020]

According to the present invention, the solder-wetting metal layer having the terminal electrodes of the chip-shaped electronic component formed on the end surface and the peripheral surface of the end portion, and the solder having poor wettability with the molten solder formed on the end surface of the wetting metal layer. Since it is composed of a non-wetting metal layer, when surface-mounting a chip-shaped electronic component on a printed circuit board, both end terminal electrodes of this electronic component are soldered to the soldering lands of the printed circuit board by reflow soldering or flow soldering. However, since the molten solder does not get wet to the terminal electrodes on the end surface of the chip-shaped electronic component, the molten solder does not adhere to it, and this component is not pulled to either end side, preventing the chip standing phenomenon. be able to. on the other hand,
Since the solder-wetting metal layer is well soldered to the soldering land, the solder-wetting metal layer and the non-solder-wetting metal layer are connected to each other so that a terminal electrode such as a chip type multilayer capacitor is provided on the end face. 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 wet metal layer 3, 3 ・ ・ Solder non-wet metal layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location H01G 13/00 391 B 9174-5E (72) Inventor Yoichi Mizuno 6-16 Ueno, Taito-ku, Tokyo No. 20 Taiyo Yuden 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 in which a good solder-wettable metal layer is provided, and a solder-non-wettable metal layer that is poorly wetted by molten solder is provided on the solder-wettable metal layer on both end faces 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 the both end surfaces of the chip-shaped electronic component element body and the peripheral surfaces of the both side end portions following the electrode material paste in an electrode material paste containing a metal that is wettable by molten solder. And a first electrode coating film forming step of forming a film, and a metal having poor wettability with molten solder is contained on the electrode coating film on both end surfaces of the chip-shaped electronic component element body formed by the first electrode coating film forming step. The method of forming a terminal electrode for a chip-shaped electronic component according to claim 1, further comprising a second electrode coating film forming step of forming an electrode material paste coating film.