JPH0273659A - Lead frame for semiconductor device - Google Patents

Abstract

PURPOSE:To prevent silver plating from leaking from its side face, to easily manufacture to finish solder plating in a sheath plating step, and to improve the reliability of a lead frame by forming at least one protrusion on two side face of the inner leads of a frame for a resin-sealed semiconductor device. CONSTITUTION:Protrusions 6 are formed on the side faces of the inner leads 2 of a lead frame for a semiconductor device, and formed by pressing or etching at the time of manufacture of the frame. The protrusions 6 are provided at the leads 2 thereby to shut OFF the leakage of the silver plating by the protrusions 6 to prevent a silver plating film 5 from forming to the side face of outer leads 3. This process prevents the silver plating from leaking to the side face to easily manufacture solder plating finish in a sheath plating step, thereby improving the reliability of the frame.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lead frame for a semiconductor device, and particularly to a lead frame for a resin-sealed semiconductor device.

[Conventional technology]

Conventionally, the inner leads of lead frames (hereinafter referred to as lead frames) for resin-sealed semiconductor devices have wire bonding at their tips to the electrodes of the semiconductor elements mounted on the island section 1, as shown in FIG. In order to facilitate bonding when connecting wires, a silver plating film 5 with a thickness of several μm is deposited.

When applying the partial silver plating film 5 to the inner lead 22, masking is normally performed to form the silver plating film 5 only on the necessary parts, but since the sides of the inner lead 22 are not masked, conventional In the shape of the inner lead 22, the silver plating leaked and a silver plating film 5 was formed up to the tie bar 4.

[Problem to be solved by the invention]

In the conventional lead frame described above, if there is a thin silver plating film on the side surface near the tie bar, when applying exterior plating such as solder plating to the outer lead, the silver will be removed from the lead frame during pretreatment in the exterior plating process. The plating film peels off.
However, there is a drawback that the solder plating grows abnormally and short-circuits occur between adjacent outer leads.

An object of the present invention is to provide a highly reliable lead frame for a semiconductor device that does not cause short-circuits between adjacent outer leads.

[Means to solve the problem]

The present invention provides a lead frame for a resin-sealed semiconductor device, in which an inner lead has at least one protrusion on each of two side surfaces.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view of essential parts of a first embodiment of the present invention, and FIG. 2 is an enlarged perspective view of the inner lead shown in FIG. 1.

In the first embodiment, as shown in FIGS. 1 and 2, convex portions 6 are provided on each of the two side surfaces of the inner lead 2. As shown in FIGS. This convex portion 6 can be formed during production of the lead frame by pressing or etching.

In this way, by providing the protrusions 6 on the inner leads 2, leakage of silver plating is blocked by the protrusions 6, and it is possible to prevent the silver plating film 5 from forming on the side surfaces of the outer leads 3. Can be done.

FIG. 3 is an enlarged perspective view of an inner lead according to a second embodiment of the present invention.

In the second embodiment, as shown in FIG. 3, two side surfaces of the inner lead 12 are each provided with a hook-shaped convex portion 16 bent toward the island. By forming the convex portion 16 into a hook shape in this manner, the effect of preventing silver plating leakage is further ensured, and it is possible to prevent the silver plating film 5 from being formed on the side surface of the outer lead.

〔Effect of the invention〕

As explained above, the present invention prevents silver plating from leaking from the sides by forming convex portions on a portion of two side surfaces of the inner lead of a lead frame, thereby improving the solder plating finish in the exterior plating process. This has the effect of making it easier and significantly improving reliability.

[Brief explanation of the drawing]

FIG. 1 is a plan view of main parts of a first embodiment of the present invention, FIG. 2 is an enlarged perspective view of the inner lead of FIG. 1, and FIG. 3 is an inner lead frame of a second embodiment of the present invention. FIG. 4 is an enlarged perspective view of a lead and a plan view of a main part of an example of a conventional lead frame. 1...Island, 2,12.22...Inner lead, 3...Outer lead, 4...Tie bar, 5
...Silver plating film, 6, 16...Convex portion, 7...Resin sealing line.

Claims (1)

[Claims] A lead frame for a resin-sealed semiconductor device, characterized in that each of two side surfaces of an inner lead has at least one convex portion.