JPH04237155A - Electronic component - Google Patents

Abstract

PURPOSE:To enable a lead to be enhanced in wettability to solder including its tip, to form a solder fillet even on the tip of the lead, to enable the visual inspection of the lead to be carried out, and to enhance the lead in soldering strength. CONSTITUTION:A main body 2 of an electronic component 1 is provided with a lead 3 which extends outward from its side, the lead 3 is bent downward to be nearly level with the underside of the main body 2 and then made to extend outward horizontally again, a joint 4 joined to an electrode 6 provided to a circuit board 5 is provided to the tip of the lead 3, a tip riser 7 which extends obliquely upward is provided to the tip of the joint 4 of the lead 3, and a solder fillet 11 is formed between the side face of the tip riser 7 excellent in solder wettability and the electrode 6 of the circuit board 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic components, and more particularly to electronic components in which the quality of lead soldering is improved.

0002

[Prior Art] Electronic components include chip-type electronic components that have bonding electrodes on the main body, and chip-type electronic components that have a large number of leads protruding from the side of the main body, depending on the form of the bonding part to the electrode of the circuit board. There are electronic parts. In this lead-equipped electronic component, known lead shapes include a gull wing lead as shown in FIG. 4, a butt lead as shown in FIG. 5, and a J lead as shown in FIG.

The gull-wing lead 21 shown in FIG. 4 can have a wide joint 22 to the electrode 23 of the circuit board 23, so that relatively high soldering strength can be obtained, whereas the gull-wing lead 25 shown in FIG. Since 25a only faces the electrode 24 of the circuit board 23, the soldering strength is 60 to 70% weaker than that of the gull wing lead 21, and the reliability of the solder joint is low, so it is not common. The J-lead 26 shown here is used only for special electronic components, such as when there are severe restrictions on the placement space of electronic components, as it is difficult to improve the processing accuracy of the leads. The problem is that it is not suitable for Therefore, the gullwig lead 21 is generally employed, although it requires a somewhat large installation space.

0004

[Problems to be Solved by the Invention] However, as described above, the gull wing lead 21 also has the following problems. That is, as shown in detail in FIG. 7, a metal film 27 made of tin, solder, or the like that has good wettability with solder is formed on the surface of the lead 21, but the lead 21 forms the main body of the electronic component. After that, the tip is finally cut and molded, so the copper of the lead material is directly exposed at the tip 21a, resulting in poor wettability with solder. Therefore, a solder fillet is not formed at the tip 21a of the lead 21 in a bonded state, and the solder bonded state cannot be inspected by visual inspection of the solder fillet, resulting in a problem that the process for inspecting the bonded state becomes complicated. In addition, since no solder fillet is formed, for example, the lead width is 2 mm.
The problem is that the limit is 700 gf/lead, and the soldering strength is not sufficient.

These problems are becoming increasingly important, especially as lead pitches become narrower, electronic components become thinner, and soldering becomes higher quality.

[0006] In the J lead 26, a solder fillet is formed as shown in FIG. Therefore, visual inspection of solder fillets is difficult.

In view of the above-mentioned conventional problems, the present invention provides good solder wettability up to the tip of the joint of the lead to the electrode of the circuit board, and a solder fillet is formed even at the tip of the lead, resulting in a poor appearance of the bonded state. The purpose of the present invention is to provide an electronic component that can be inspected and has high soldering strength.

[0008]

[Means for Solving the Problems] The electronic component of the present invention has a main body and a lead extending outward from the side surface thereof, and the lead is directed downward from the lower surface of the main body and further extends outward. The electronic component is characterized in that the tip side of the bonding portion of the lead to the circuit board is oriented obliquely upward in an electronic component in which the bonding portion of the lead to the circuit board is formed at the tip end thereof. .

[0009]

[Operation] According to the electronic component of the present invention, the tip side of the joint part of the lead to the circuit board is oriented diagonally upward, so even if the solder wettability is poor, the lead tip can be oriented diagonally upward. A solder fillet at the lead tip is formed between the side surface of the tip where the solder has good wettability and the electrode of the circuit board, and the solder fillet at the lead tip makes it possible to visually inspect the joint condition and improve the soldering strength. Furthermore, by bending the tip of the joint portion of the lead, the rigidity of the tip of the lead is increased, and deformation during transportation after the lead is formed is less likely to occur.

0010

[Embodiment] Below, an electronic component according to an embodiment of the present invention is shown in FIG.
This will be explained with reference to FIG.

In FIG. 1, reference numeral 1 denotes an electronic component mounted on a circuit board 5, and a plurality of leads 3 protrude outward from the four circumferential side surfaces of the main body 2. As shown in FIG. Each lead 3 is bent downward at an appropriate distance from the side surface of the main body 2, and then bent horizontally outward again at a position slightly below the bottom surface of the main body 2. A flat joint portion 4 of an appropriate length is formed closer to the distal end. The electronic component 1 is mounted on the circuit board 5 so that the joint portion 4 overlaps the electrode 6 of the circuit board 5.

[0012] The tip end of the joint portion 4 of each lead 3 is bent obliquely upward to form a tip upright portion 7.

Further, as shown in detail in FIG. 2, the surface of the lead 3 is coated with tin plating 8 or solder plating except for the cut surface at the tip of the lead 3, and the surface of the lead 3 is coated with tin plating 8 or solder plating.
It has good wettability with.

An adhesive 10 is interposed between the circuit board 5 and the main body 2 of the electronic component 1 for temporarily fixing the electronic component 1 until it is soldered after the electronic component 1 is mounted. .

In the above configuration, in order to mount the electronic component 1 on the circuit board 5, the adhesive 10 is applied to a position on the circuit board 5 corresponding to the main body 2 at the electronic component mounting position, and at the same time, the adhesive 10 is applied to the position corresponding to the lead 3. Cream solder is applied onto the electrodes 6, and the electronic component 1 is mounted on the circuit board 5, and its main body 2 is temporarily fixed with an adhesive 10. Thereafter, the circuit board 5 with the electronic component 1 mounted thereon is passed through a reflow device to heat and melt the cream solder, and the bonded portion 4 of the lead 3 is
and the electrodes 6 of the circuit board 5 are bonded using a bonding solder 9.

In this solder joint, since the surface of the lead 3 is coated with tin plating 8 or the like which has good wettability with solder, a highly reliable joint is ensured, and the tip of the joint part 4 is Since the raised portion 7 is provided, the solder fillet 11 is reliably formed also at the tip of the lead 3, as shown in detail in FIG. Thus, solder fillet 1
1, it becomes possible to visually inspect the joint state, and the soldering strength is improved. For example, with a lead width of 2 mm,
Soldering strength of 0 gf/lead or more can be ensured.

The tip rising portion 7 has a height H of 1.5t or more, where the thickness of the lead 3 is t, an inclination angle θ with respect to the horizontal plane of 30° or more, and a radius of curvature r of t or more. . That is, the height H and the inclination angle θ of these tip rising portions 7
, if the radius of curvature r is smaller than the above value, the solder fillet 1
1 becomes difficult to form.

Furthermore, by bending the ends of the joints 4 of the leads 3, the rigidity of the ends of the leads 3 is increased. Deformation can be reduced.

In the above embodiment, the shape of the lead 3 is such that the flat joint portion 4 is provided in order to ensure a wide joint area with the electrode 6 of the circuit board 5 and to ensure the necessary soldering strength.
In the present invention, since the solder fillet 11 is reliably formed also at the tip of the lead 3, a U-shaped joint 14 may be used as shown in FIG. Since the solder fillets 11 are reliably formed on both sides of the joint part 14, the required joint strength can be secured, and the appearance of the joint state can be inspected. Furthermore, a large space is saved on the outer periphery of the main body. , the mounting space can be reduced.

[0020]

[Effects of the Invention] According to the electronic component of the present invention, the tip side of the joint part of the lead to the circuit board is oriented diagonally upward, so even if the solder wettability is poor, the lead tip can be oriented diagonally upward. A solder fillet at the lead tip is formed between the side surface of the oriented tip with good solder wettability and the electrode of the circuit board, making it possible to visually inspect the bonding condition by the solder fillet at the lead tip. Not only can the condition be easily inspected, but also the soldering strength can be greatly improved. Therefore, it is highly effective in narrowing the lead pitch, making electronic components thinner, and improving the quality of soldering. Furthermore, by bending the tip of the joint portion of the lead, the rigidity of the tip of the lead can be increased, making it difficult for the lead to be deformed during transportation after being formed.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of an electronic component according to an embodiment of the present invention in a mounted state.

FIG. 2 is an enlarged cross-sectional view of the lead tip of the electronic component in FIG. 1;

FIG. 3 is a partial cross-sectional view of an electronic component according to another embodiment of the present invention in a mounted state.

FIG. 4 is a partial cross-sectional view of an electronic component having a conventional gull-wing lead in a mounted state.

FIG. 5 is a partial cross-sectional view of a mounted state of an electronic component having a conventional butt lead.

FIG. 6 is a partial cross-sectional view of a mounted state of an electronic component having a conventional J lead.

7 is an enlarged sectional view of the lead tip of the electronic component shown in FIG. 4; FIG.

[Explanation of symbols]

1 Electronic parts 2 Main body 3 Lead 4 Joint part 5 Circuit board 6 Electrode 7 Tip rising part 9　Join solder 11 Solder fillet 14 Joint part

Claims (1)

[Claims] Claim 1: A main body and a lead extending outward from the side thereof, the lead being directed downward from the lower surface of the main body, and then directed outward again to reach the distal end. What is claimed is: 1. An electronic component having a bonded portion to an electrode of a circuit board, characterized in that the tip side of the bonded portion of the lead to the circuit board is oriented obliquely upward.