JPH0621237U - Chip parts - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a chip part that can prevent the rise of the chip part and prevent a decrease in productivity due to rework. [Structure] A thickness dimension of an upper surface of an electrode terminal 71 provided at both ends of a solid component 61 of a chip component is made smaller than a thickness dimension of a bottom surface thereof, and a side shape of the chip component is a trapezoid.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a chip component having no lead wire and having electrode terminals covering both ends of a solid component.

[0002]

[Prior art]

 In recent printed wiring boards, the mounting density of components has dramatically increased due to the adoption of chip components and higher density of printed wiring circuits. The chip parts are soldered to the printed wiring board by the reflow method or the dipping method. When soldering by the reflow method, cream solder is applied to the soldering points (hereinafter referred to as pads) on the wiring circuit conductor by screen printing, etc. It is temporarily fixed in position and heated in an electric furnace or infrared furnace.

FIG. 3 is an explanatory diagram of this process. In FIG. 3, (A) shows a pad and a chip component to which cream solder is applied. In FIG. 3, 1 is a printed wiring board, 2 is a wiring circuit conductor, and 3 is a wiring circuit conductor. Is a pad, and 4 is a cream solder printed and applied on the pad 3. The printed wiring board 1 is coated with solder resist except for parts connecting portions such as pads. The chip component 5 is composed of a solid component 6 such as a resistor or a capacitor, and electrode terminals 7 provided so as to cover both ends of the solid component 6. (B) is a diagram showing a state after reflow soldering, and 8 is a solder fillet. (C) is a diagram showing a chip component that has stood up during reflow soldering, 9 is solder that has been melted and solidified on the pad, and 10 is solder that fixes the stood chip component 5. This rising phenomenon of chip components is known as the tombstone phenomenon, and is a unique phenomenon that occurs when the chip components used for surface mounting become minute, and reflow is arranged along the transfer direction during soldering. It tends to occur in small chip parts.

FIG. 4 is a cross-sectional view of the chip capacitor 5a portion for explaining the rising phenomenon. 6a is a monolithic ceramic capacitor which is a solid part, and 7a and 7b are provided so as to cover both ends of the solid part 6a. The electrode terminals are provided, 11 is the molten solder, and 12 is the conveyance direction of the printed wiring board 1. The solder 11 in which the cream solder is melted by being first heated in the heating furnace does not have the shape like the solder fillet 8 shown in FIG. 3 (B) but has a swelled shape, and for some reason, the contact angle θ Becomes larger, the clockwise rotational force due to the surface tension T of the solder 11 exceeds the counterclockwise rotational force due to the weight of the chip component 5a and the adhesive force between the electrode terminal 7b and the cream solder 4. It rises like the chip component 5 of 3 (C). In this phenomenon, the ratio of the pad surface area to the size of the chip component is large for the micro chip component, and since the thickness of the screen is constant, the amount of cream solder supplied to the micro chip component is relatively large. It is not believed that such swells are likely to occur.

[0005]

[Problems to be solved by the device]

 Standing up chip components can be easily found by visual inspection, but since the mounting density of the components is high and they are minute components, rework work using tweezers, a soldering iron with a fine tip, and a magnifying lens. Is not easy, and a large number will significantly reduce productivity.

In view of the above points, an object of the present invention is to provide a chip component that can prevent the chip component from rising and prevent the productivity from being lowered due to the reworking work.

[0007]

[Means for Solving the Problems]

The means for solving the above problems in the present invention is to make the thickness dimension L ₁ of the upper surface of the electrode terminal provided at the side end of the solid component in the chip component smaller than the thickness dimension L ₂ of the bottom surface of the soldering surface. .

[0008]

[Action]

In the case of chip parts of the same height, the thickness dimension L ₁ of the upper surface of the electrode terminal is made smaller than the thickness dimension L ₂ of the bottom surface, so the end surface of the electrode terminal becomes a slope and the contact area with the solder increases and the solder rises. Disappears.

[0009]

【Example】

 The present invention will be described below based on an embodiment shown in the drawings.

FIG. 1 is a perspective view of a chip part according to an embodiment of the present invention as viewed from above, in which 61 is a solid part and 71 is an electrode terminal provided on an end surface of both side ends of the solid part 61. Then, the thickness dimension L ₁ on the side opposite to the soldered surface (hereinafter referred to as the top surface) is made smaller than the thickness dimension on the soldering surface side (hereinafter referred to as the bottom surface), and the solid component 61 and the electrode terminal 71 are formed. The side surface shape of the chip component 51 to be formed is trapezoidal.

FIG. 2 is a front view of an embodiment in which the chip component is a chip capacitor, 51a is a chip capacitor having a trapezoidal side surface, 61a is a monolithic ceramic capacitor as a solid component, and 71a and 71b are solid component 61a sides. In the electrode terminals provided at the ends, the thickness dimension L ₁ of the upper surface is smaller than the thickness dimension of the bottom surface. The printed wiring board 1 is conveyed in the direction of the arrow 12, the previously melted solder 13 rises gently along the slope, the contact angle θ is small, and the clockwise rotational force due to the surface tension T of the solder is chip parts. Since the counterclockwise rotation force due to the self-weight of 51a and the adhesive force between the electrode terminal 71b and the cream solder 4 cannot be exceeded, the chip component 51a rotates clockwise, and the chip component 5 as shown in FIG. Will never stand up. After that, the cream solder 4 on the electrode terminal 71b side is also heated, and the molten solder gently rises and adheres along the inclined surface similarly to the electrode terminal 71a side. Although Ag or Ag-Pd is used for the electrode terminals and the solderability of the terminals is good, and the flux with good wettability is used for the cream solder, it is shown in Fig. 4 that the solder supply amount is too large. It is thought that solder swelling may occur and a large contact angle may occur. Therefore, it is necessary to suppress the solder supply amount by making the window hole provided in the cream solder coating screen smaller than the surface area of the pad in the case of microchip parts.

In the above description, the side of the chip capacitor is described. However, in the case of a chip resistor, only the outer periphery of the solid part between the electrode terminals provided at both ends is covered with an insulating coating, and the structure of the chip capacitor is reduced. Is no different. Further, in the above embodiment, the case where the thickness dimension of the electrode terminals at both ends is set to L ₁ <L ₂ has been described. However, even if only the thickness dimension of the electrode terminal on the front side in the traveling direction is set to L ₁ <L ₂ , the tombstone is set. The occurrence of the phenomenon can be prevented.

[0013]

[Effect of device]

In the chip component according to the present invention, the relationship between the thickness dimension L ₁ of the upper surface and the thickness dimension L ₂ of the bottom surface of the soldering surface of the electrode terminal provided at the side end of the solid component is L ₁ <L _2. Therefore, the end face of the electrode terminal becomes a slope, the contact area with the solder increases, and the solder adheres gently along the slope without rising. Therefore, even if the solder on both electrode terminals does not melt at the same time and the solder on the electrode terminal on one side melts first, the chip component does not rise, and troublesome reworking work is unnecessary, preventing a drop in productivity. That is, it has a practical effect.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is an explanatory view of the present invention.

FIG. 3 is a conventional explanatory view. FIG. 3A is a perspective view showing a pad and a chip component to which cream solder is applied. FIG. 6B is a perspective view showing a state after reflow soldering. FIG. 6C is a perspective view showing a state in which the chip component has stood up.

FIG. 4 is a conventional perspective view.

[Explanation of symbols]

54 ... chip component 61 ... the thickness of the solid part 71 ... electrode terminal L ₁ ... thickness L ₂ ... bottom surface of the upper surface

Claims (1)

[Scope of utility model registration request] 1. A chip component comprising a solid component and an electrode terminal provided at a side end portion of the solid component, the bottom side of which is soldered to a chip component, and the thickness dimension of the upper face side of the electrode terminal. A chip part characterized in that L ₁ is smaller than the thickness dimension L _{2 of the} bottom surface.