JPH08264925A - Method for soldering lead terminal of surface mounting component - Google Patents

Abstract

PURPOSE: To easily inspect visually and optically the appearance of soldered components so as to prevent the occurrence of solder bridges by alternately arranging solder paste on the outer and inner sides of points at which the lead terminals come into contact with component pads. CONSTITUTION: Solder paste 10a or 10b is printed to the front and rear sides of points at which V-shaped (T-shaped) lead frames 5 come into contact with component pads 3. Namely, the solder paste 10a and 10b are alternately arranged against the lead frames 5 arranged in a line and the solder paste is reflowed. Therefore, visual and optical appearance inspections of soldered components can be performed easily, because heel fillets are formed on the front side of the frames 5. In addition, the formation of bridges between the solder paste 10a and 10b can be prevented, because the paste 10a and 10b are alternately printed on the front side and rear side of the frames 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for soldering lead terminals of surface mount components.

[0002]

2. Description of the Related Art Conventionally, a surface mount component has a gull wing type lead frame 2 protruding from a body 1 of the component as shown in FIG. When soldering the lead frame, the solder paste 10 is printed on the component pads 3 on the substrate 4, as shown in FIG. The gull-wing type lead frame 2 is mounted on the solder paste 10, and solder reflow is performed for soldering. Heat is applied to perform solder reflow, but this heat causes the solder paste 10 to easily cause the bridge 11 before melting the solder,
Even after soldering, the bridge 11 exists and becomes defective.
The solder fillets formed on the gull wing type lead frame 2 are a toe fillet 8 and a heel fillet 9 as shown in FIG. Since the heel fillet 9 having the largest amount of solder becomes a blind spot and cannot be seen, and the toe fillet 8 has a small fillet height h, the optical appearance inspection using the light source 6 and the CCD camera 7 causes insufficient solder. It was difficult to detect defects such as solder leak defects and solder bridges. Gull wing type lead frame 2
In this case, as the heel fillet 9, which most affects the soldering strength, becomes finer, the formation of the fillet becomes unstable as the pitch becomes finer, and it is difficult to secure the soldering strength.

[0003]

In the conventional gull wing type lead frame 2, since the heel fillet is formed on the rear side of the lead frame, when the lead pitch becomes narrow, it is visually observed, and the appearance of soldering by an optical method using a CCD camera is performed. The inspection was difficult. Further, the heel fillet having the largest amount of solder is adjacent only to the rear side of the lead frame, so that there is a problem that a solder bridge is easily generated.

[0004]

According to the present invention, there is provided a method of soldering a lead terminal of a surface mount component, wherein V and J lead terminals extending outside the body of the surface mount component are arranged side by side. Mounted on the solder paste previously set in the
When soldering by solder reflow, the solder paste corresponds to any one of the outer and inner positions of the lead terminal with a V-shaped or J-shaped bent portion where the lead terminal contacts the component pad as a boundary. In such a manner that they are alternately arranged.

[0005]

The present invention will be described below with reference to the drawings.

FIG. 1 shows a lead frame 5 of a surface mount component according to an embodiment of the present invention. The lead protruding outward from the body 1 is formed in a V or J shape so as to contact the component pad 3 on the substrate 4.

FIG. 2 shows the appearance of soldering the lead frame 5. After soldering, heel fillets 9a and 9b are formed before and after the lead frame 5, respectively. In the conventional gull-wing type lead frame, the heel fillet having the largest amount of solder becomes a blind spot, and it is difficult to visually inspect and optically inspect the soldering appearance. Outline V (J)
In the lead frame 5, since the heel fillet 9a having a sufficient fillet height h is formed on the front side of the lead frame 5, visual and optical soldering appearance inspection is easy.

FIG. 3 shows a lead frame 5 before solder reflow.
2 shows an arrangement relationship between the solder pastes 10a and 10b. V
(J) The solder paste 10a or 10b is printed before and after the contact point of the lead frame 5 with the component pad 3. That is, as described above, the solder pastes 10a and 10b are alternately arranged on the lead frames 5 arranged side by side, and the solder reflow is performed. This can prevent solder bridging.

[0009]

As described above, according to the present invention, since the visible heel fillet is formed on the front side of the lead frame (lead terminal) by making the shape of the lead frame (lead terminal) V or J, it is possible to perform visual and optical inspection. -Type soldering visual inspection becomes easy. Also, by printing the solder paste on the lead frame before and after, the bridge of the solder paste can be prevented.

[Brief description of drawings]

FIG. 1 shows a lead frame shape according to an embodiment of the present invention.

FIG. 2 shows a state after appearance inspection and soldering of the lead frame shown in FIG. 1;

FIG. 3 shows a state before soldering the lead frame shown in FIG. 1;

FIG. 4 shows a conventional lead frame shape.

FIG. 5 shows a state after the appearance inspection and soldering of the lead frame shown in FIG. 4;

FIG. 6 shows a state before the lead frame shown in FIG. 4 is soldered.

[Explanation of symbols] 1 body 2 gull wing type lead frame 3 component pad 4 substrate 5 V (J) type lead frame 6 light source 7 CCD camera 8 toe fillet 9, 9a, 9b heel fillet 10, 10a, 10b solder paste 11 solder bridge

Claims (1)

[Claims] 1. When mounting V-shaped or J-shaped lead terminals, which extend outward from the body of surface-mounted components and are juxtaposed with each other, on a solder paste previously installed on component pads of a substrate and soldering by solder reflow And alternately arranging the solder paste so as to correspond to either an outer position or an inner position of the lead terminal with a V-shaped or J-shaped bent portion where the lead terminal contacts the component pad as a boundary. Characteristic Surface mounting component Lead terminal soldering method.