JPH087644Y2 - Semiconductor device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a semiconductor device in which the pitch of external leads is close.

2. Description of the Related Art In recent years, high-density mounting of electronic components has been promoted in order to miniaturize electronic devices. However, as semiconductor devices with many leads such as integrated circuit components become smaller, the pitch of external leads increases. It is getting smaller.

For example, in a resin-packaged integrated circuit component as shown in FIG. 5 which is formed into a flat package for surface mounting, the number of external leads per unit is large and the pitch is large.
It is extremely small, less than 0.8 mm.

When mounting a semiconductor device having a small pitch of external leads on a printed circuit board as described above, as shown in FIG. 4, the external leads 2 are uniformly cut and bent. Is soldered to a printed circuit (not shown) via a solder pad 9 prepared in advance on the circuit. At that time, a solder bridge occurs between adjacent solder pad portions and short circuits frequently occur. There was a problem of doing.

Particularly, when the lead pitch is 1.0 mm or less, it is extremely difficult to perform stable mounting without a solder bridge.

Means for Solving the Problems In order to solve the above problems, according to the present invention, a semiconductor device is formed by using a lead frame having a plurality of external leads separated from the outer frame by every other line. The external leads are bent at the same position in each of two places, and the tips of the external leads are soldered to the solder pad portions in correspondence with the solder pad portions arranged in a staggered pattern on the surface mounting circuit board. It is characterized in that it is arranged in a zigzag shape and has a wide tip end portion of the external lead so that it can be soldered to the solder pad portion.

Effect According to the semiconductor device of the present invention, the tips of the external leads are zigzag in a predetermined length such that every other tip can be soldered corresponding to the solder pads arranged in a zigzag pattern on the surface mounting circuit board. Since it has a structure that is arranged on the surface mounting printed circuit board, every other solder pad portion corresponding to the tip of the external lead has a wide arrangement interval.
It is possible to realize stable board mounting without a solder bridge between solder pad portions.

Embodiment Hereinafter, one embodiment of the present invention will be described with reference to the drawings in comparison with a conventional example.

FIG. 1 is a plan view for explaining the structure of a lead frame used in the semiconductor device of the present invention, and FIG. 2 is a perspective view of a main part of the semiconductor device of the present invention.

In FIG. 1, 1 is a lead frame main body, 2 and 3 are external leads, 4 is an outer frame, 5 is a tie bar, 6 is a semiconductor element adhesion planned portion, 11 is a resin sealing cover range, and 13 is an external lead cut planned line. Is. In FIG. 2, 7 is resin and 10
Is a circuit board, 12 is a flat package type electronic component, 92 and
93 is a solder pad part.

FIG. 3 shows the structure of a conventional lead frame, and FIG. 4 shows the structure of a conventional semiconductor device. The same parts are designated by the same reference numerals.

In FIG. 3, the outer leads 2 are all continuous with the outer frame 4, and correspondingly, in FIG. 4, the solder pad portion 9 is also aligned, whereas in FIG. The external lead 2 that is continuous with the outer frame 4 and the outer lead 4 that is not continuous with the outer frame 4 and has a predetermined length that allows the tips to be soldered to the solder pads arranged in a staggered pattern on the surface mounting circuit board. There is a frame 4 and external leads 3 separated from each other, and the external leads 2 and the external leads 3 are alternately arranged.

Even if this lead frame structure is adopted, the number of punching steps, that is, the number of punches is the same as in the case of the conventional lead frame, and the shorter outer lead 3 is formed from the tip surface of the outer lead 3. The L-shaped surface reaching the side surface can be punched at once, and since the length of the external lead 3 is short, the tip of the lead does not escape and deform during the punching process due to its strength. As a result, the quality after molding is improved. Remarkably improved.

FIG. 2 shows a resin-sealed semiconductor device of the present invention formed by using a lead frame in which such external leads are arranged.

In the semiconductor device of the present invention, the long outer lead 2 and the short outer lead 3 are bent at the same position in each of two places, and the tips are formed in a zigzag shape. Pad 92
In addition, the external lead 3 is formed with a length corresponding to the solder pad 93, and the tip of the external lead is wide. With this structure, the distance between the tips of the external leads is larger than the distance between the tips of the external leads having a uniform length, as shown in FIG.

That is, since the distance d is formed as shown in FIG. 2, the occurrence of solder bridge is suppressed.

In the semiconductor device of the present invention, long and short external leads are cut and bent after resin sealing using the lead frame shown in FIG. 3 to form the external leads in a zigzag shape.
This is not to be mounted on a printed circuit board, but the lead frame shown in FIG.
It is formed by cutting and bending the external leads after resin sealing.

The reason is that when the lead frame shown in FIG. 3 is used, it is necessary to form the structure of the cutting die in a zigzag shape in the cutting and bending after the resin sealing. Although the mold is extremely expensive to manufacture and maintenance of the mold is difficult to perform, the lead frame of this embodiment shown in FIG. 1 can use the conventional mold structure as it is.

Effect of the Invention According to the present invention, every other wide tip of the external lead is separated from the outer frame by a predetermined length that can be soldered to the solder pad portions arranged in a staggered pattern on the surface mounting circuit board. Since the semiconductor device is formed using the existing lead frame, the tips of the external leads can be formed in a zigzag pattern every other one, even though the external leads are cut and bent as in the conventional case. As a result, when the printed circuit board is mounted, the distance between the tips of adjacent external leads increases, and solder bridges do not occur even through the solder pads. Therefore, it is extremely effective to prevent the production of circuit boards with fatal defects such as short circuits. It is something.

[Brief description of drawings]

FIG. 1 is a plan view of an essential part for explaining a lead frame used in an embodiment of the present invention, and FIG. 2 is a resin-encapsulated semiconductor device using the lead frame in a printed circuit board according to an embodiment of the present invention. FIG. 3 is a plan view of a main portion of a conventional lead frame, and FIG. 4 is a resin-sealed semiconductor device using the conventional lead frame mounted on a printed circuit board. FIG. 5 is a plan view and an elevation view of a flat packaged electronic component showing a state in which the electronic components are mounted. 1 ... Lead frame body, 2 ... External lead, 3 ...
External leads separated from the outer frame, 4 ... Outer frame, 5 ... Tie bar, 6 ... Scheduled area for bonding semiconductor elements, 9,92,93 ... Solder pad area, 11 ... Scheduled area for resin cover, 12 ... … External lead cut scheduled line.

Claims (1)

[Scope of utility model registration request] 1. A semiconductor device is formed by using a lead frame having a plurality of external leads that are separated from the outer frame every other one, and the external leads are bent at the same positions in two places. A semiconductor device, wherein the tip portions are arranged in a zigzag shape, and the tip portions of the external leads are wide enough to be soldered to the solder pad portion.