JPH0327558A - Lead frame for mounting semiconductor device - Google Patents

Abstract

PURPOSE:To prevent a lead from being pulled out and improve moisture resistance by curving one part of a lead within a sealed resin. CONSTITUTION:One part of a lead frame 1a of leads 3a-3d connected to a semiconductor device electrically with a metal thin wire is curved for forming a curved part 3a' and for resin-sealing. This curving machining prevents a lead from a being pulled out without reducing the area of connection areas 7a-7d of the metal thin wire or the area of semiconductor device mounting parts 8a-8d and extends the leak path at the interface between a sealing resin 6a and the leads 3a-3d, thus improving moisture resistance against water and impurities entering the device.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a lead frame 1\, and in particular, in a resin-sealed semiconductor device, it can be used without reducing the effective area of the lead frame 1 for connecting thin metal wires. Also, without the lead {”}
The present invention relates to a lead frame that can improve moisture resistance without causing any defects.

Conventional technology Conventionally, in mini-mold packages with about 3 to 5 pins that have Pellet mount leads and leads, the leads inside the sealing resin (hereinafter referred to as inner leads) are formed flat. , as shown in FIG. 3, the effective area of the inner lead connecting the thin metal wire (the thin metal wire connection area 7e to 7h) is reduced and a notch is inserted, or
Or, as shown in Figure 4, the area on which the pellets are mounted on the mount lead (pellet 1 to ti mounting areas 8e, 8f)
) was made smaller and a key hand was attached to the inner lead to prevent the lead from slipping out.

In addition, in the conventional elliptical structure, moisture and impurities that penetrate through the interface between the resin and the lead reach the pellets at the fastest speed, deteriorating the moisture resistance of the product.

FIGS. 3 and 4 show a conventional example, and FIG. 3 is a plan view of a lead frame when notches are made in the leads, and it can be seen that the area to which thin metal wires can be connected is reduced. FIG. 4 is a plan view of the case where a key hand is provided on the pellet 1, and it can be seen that the area for carrying the pellet 1 becomes smaller.

Problems to be Solved by the Invention As mentioned above, conventional lead frames for mini-molt packages do not have the depression process or complicated shape of the inner 1 seen in lead frames for ICs, and in particular, the leads are flat and It has a straight line shape. For this reason, the leads will fall out after they are sealed with resin and separated from the lead frame, so either make a notch in the inner lead part or add a key to the width of the lead to prevent the leads from falling out. I'm here.

However, in the former structure (FIG. 3), the effective area for connecting thin metal wires is reduced by about 25%, and there is a drawback that optimal connection may not be possible depending on the type of pellet.

In addition, the latter (FIG. 4) tflI construction has the disadvantage that the area for loading pellets 1 to 1 is approximately 30% smaller, and because only pellets of a limited size can be loaded, it is not possible to expand the product line.

Furthermore, since the lead shape is linear, moisture and impurities that enter from the interface between the resin and the lead proceed most quickly under the same conditions, and moisture resistance is the lowest.

The present invention has been made in view of the above-mentioned drawbacks of the conventional technology, and therefore, an object of the present invention is to provide a novel lead frame that makes it possible to eliminate the above-mentioned disadvantages inherent in the conventional technology. There is a particular thing.

Difference of the Invention from the Prior Art The present invention differs from the above-described conventional lead frame in that a portion of the inner lead is curved.

Means for Solving the Problems In order to achieve the above-mentioned object, the lead frame for mounting a semiconductor device according to the present invention is provided by bending a part into a curved shape without providing a notch or key handle in the inner lead. It is constructed by applying

Embodiments Next, preferred embodiments of the present invention will be specifically explained with reference to the drawings.

FIG. 1(a) is a plan view showing a first embodiment of the present invention, and FIG. 1(b) is a plan view taken along line AA' in FIG. 1(a) and viewed in the direction of the arrow. There is a cross-sectional view. Figure 1 (C)
is a sectional view taken along line AA' after resin sealing. Further, FIG. 1(d) is an enlarged perspective view of the inside of section B of J-311 in FIG. 1(a).

Referring to FIG. 1(a>-(d)), leads 3a-3d
A curved portion 3a' is machined in the shape of the curved part 3a', and this process prevents the lead from coming off without reducing the thin metal wire connection area of the lead or the area of the pellet mounting area, and also reduces the interface between the resin and the lead. Since the leak path becomes longer, it is possible to improve the moisture resistance against moisture and impurities that enter from there.

Approximately 25% compared to the conventional case of notching the lead
The connection area of the thin metal wire increases, and the area of the Pellet I-mounting part increases by about 30% compared to the conventional case where the key is exposed. In addition, in terms of moisture resistance, conventionally defects occurred after about 150 hours, but computer simulations and experiments showed that it
It was found that no defects occurred until 0 hours.

FIG. 2 is FIG. 1(c) showing a second embodiment according to the present invention.
This is the same longitudinal section.

Referring to FIG. 2, the lead 3e has a rectangular bent portion 3.
e l is processed and formed. This second embodiment has the advantage that the moisture resistance can be further improved since the passage of time for moisture and impurities to penetrate is longer than that of bending into a rectangular shape.

Effects of the Invention As explained above, according to the present invention, by bending a part of the inner lead into a curved shape, the lead pullout problem can be prevented without reducing the effective connection area of the thin metal wire or the pellet loading area. In addition, the moisture resistance against moisture and impurities that enter the interface between the resin and the lead can be improved, so it has a great practical effect.

[Brief explanation of drawings]

FIG. 1(a) is a plan view showing the first embodiment of the lead frame according to the present invention, and FIG. 1(b) is the A--
A cross-sectional view cut along the A' line and seen in the direction of the arrow, FIG. 1(c) is a cross-sectional view after applying resin sealing to FIG. 1(b), and FIG. 2 is a cross-sectional view according to the present invention. A sectional view similar to FIG. 1(c) showing the 25th 6th embodiment, FIG.
FIG. 4 is a plan view showing a conventional example. 1aJb...Lead frame, 2a, 2b...Mount lead, 3a, 3b, 3c, 3d, 3e--Lead, 3a', 3e'--Curved portion, 4a, 4b,
4c, 4d, 4e, 5a, 5b, 5c, 5d, 5e--feeding hole, 6a, 6b - sealing resin, 7a, 7b, 7c,
7d, 7e. 7f, 7g, 7h...metal thin wire connection area (shaded area), 8a, 8b, 8c, 8d, 8e, 8f.
・・Pellet loading section

Claims (1)

[Claims] A lead (hereinafter referred to as a pellet) on which a semiconductor device (hereinafter referred to as a pellet) is mounted
In a lead frame having a mount lead (hereinafter referred to as a mount lead) and a lead (hereinafter referred to as a lead) that is electrically connected to the pellet by a thin metal wire, when resin sealing is performed, the leads are aligned inside the resin seal. A lead frame for mounting a semiconductor device, characterized by a bent portion.