JPS62128164A - Lead frame of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the holding strength of a resin package while preventing any water content etc. from permeating through the interface between a hanging lead and the resin package by a method wherein the sectional space of hanging lead is reduced while an auxiliary hanging lead reaching the resin package is protruded from a frame part at the position adjoining the lead. CONSTITUTION:A hanging lead 3 is narrowed on the part 3a of specified length extending from a lead frame part 6 to an element mounting part 2 to reduce the sectional space thereof. Besides, an auxiliary hanging leads 8 is protrusion- formed from the fame part 6 to the element mounting part 2 at the position adjoining the hanging lead 3. The length of hanging lead 3 is made longer than the distance between the outside of a resin package 7 to be formed in the latter process and the frame part 6. Besides, the auxiliary hanging lead 8 is set up to make at lest the end thereof resin inside the resin package 7. In such a constitution, the sectional space of hanging lead 3 is reduced so that the interface between the resin package 7 and the lead 3 may be made narrower than the conventional interface to reduce the stress in case the lead 3 is cut off.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a lead frame for a resin-molded semiconductor device, and particularly to a lead frame that can improve the reliability of a semiconductor device by increasing its airtightness and moisture resistance. Regarding.

[Conventional technology]

Conventionally, a lead frame used in a resin molded semiconductor device is constructed as a multi-lead frame 11 formed by punching a single metal plate, as shown in FIG. A mounting part 12, a hanging lead 13 for supporting the element mounting part 12 on a frame part 16 at a peripheral position, a plurality of external lead-out leads 14 arranged so as to surround the element mounting part 12, and these external lead-out leads. It is composed of a tie bar 15 that connects the leads 14 and prevents the resin from flowing outward during resin molding.

Then, a semiconductor element (not shown) is attached to the element mounting part 12, and the bonding pad of this element and the external lead-out lead 14 are connected with thin metal wires, and then a resin mold is applied to seal them. Is going. Furthermore, after this molding, the tie bars 15 are cut out, the exposed lead frame is plated with tin or solder, and the suspension leads 13, external leads 14, etc. are separated from the frame part 16 and shaped into a predetermined shape. The semiconductor device is completed by molding.

In the conventional semiconductor device described above, the end surface of the suspension lead 13 supporting the element mounting portion 12 is exposed on the surface of the molded resin package 17 even after cutting as shown in FIG. Due to heat generated from the semiconductor device itself during the heating process during device mounting and during operation, as well as stress during cutting of the suspension lead 13, a minute gap is formed at the interface between the suspension lead 13 and the resin package 17. Moisture, ionic impurities, or flux during mounting can penetrate into the semiconductor element through these gaps, causing electrical leaks and electrochemical corrosion of the aluminum that makes up the semiconductor element, causing wire breakage. It has become. In particular, the conventional hanging lead 13 is
Since the width is made relatively large to obtain the required support strength, the interface area between the suspension lead 13 and the resin package 17 in the portion protruding from the resin package 17 is increased, and the above-mentioned problem is solved. This is likely to happen.

For this reason, attempts have been made to reduce the interface area by reducing the width of the suspension lead 13, but this reduces the support strength of the resin package by the suspension lead 13 after the resin package 17 is formed, and the tie bar 15 is cut. The suspension leads 13 may be cut off during processing or plating, making it impossible to support the resin package. Therefore, a shift occurs in the relative position of the resin package 17 with respect to the lead frame 11, and the cutting die and the package interfere with each other in the subsequent cutting process of the external leads 14, etc., resulting in cracks in the resin package 17 and damage to the die. Problems such as damage may occur.

[Means for solving problems]

The lead frame for a semiconductor device of the present invention prevents moisture from entering through the interface between the suspension lead and the resin package, improves the support strength of the resin package, eliminates various problems when cutting the leads, The objective is to improve the reliability of a molded semiconductor device.

The lead frame of the semiconductor device of the present invention has a small cross section at least in a portion corresponding to the outer surface of the resin package and at least the frame portion of the suspension lead that directly supports the element mounting portion, and a position adjacent to the suspension lead. The structure is such that an auxiliary suspension lead long enough to reach the resin bag and the package protrudes from the frame part.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a plan view of one embodiment of the present invention, and FIG. 2 is a front view of a semiconductor device formed using the lead frame.

As shown in the figure, the lead frame 1 is configured as a multi-lead frame formed by punching out a single metal plate, and each unit includes an element mounting part 2 located approximately in the middle, and a surrounding area surrounding this element mounting part 2. A suspension lead 3 supported by the arranged frame part 6, a plurality of external lead-out leads 4 arranged so as to surround this element mounting part 2, and these external lead-out leads 4 are connected to prevent the resin from coming out during resin molding. It is equipped with a tie bar 5 to prevent it from flowing in the opposite direction.

The suspension lead 3 has a portion 3a extending over a required length from the frame portion 6 toward the element mounting portion 2, and its width is reduced to reduce its cross-sectional area. Forms an auxiliary suspension lead 8 projecting from the frame portion 6 toward the element mounting portion 2. The length portion 3a that reduces the width of the suspension lead 3 is located between the outer side of the resin package 7 and the frame portion 6, which will be formed in a later process.
The length of the auxiliary suspension lead 8 is set so that at least the tip thereof reaches inside the resin package 7.

Further, the width of the auxiliary suspension lead 8 is set to be as large as possible, and in this embodiment, the tip portion 8a of the holding suspension lead 8 is bent into a hook shape, and the resin package 7 is
We are trying to increase the contact area within.

According to this lead frame 1, after mounting the semiconductor element on the element mounting part 2 and performing the necessary wiring, resin molding is performed to form the resin package 7 that seals the area including the element mounting part 2, and By cutting the tie bars 5, external leads 4, etc., the resin molded semiconductor device shown in FIG. 2 can be completed. At this time, it goes without saying that the tip end 8a of the auxiliary suspension lead 8 is molded inside the resin package 7.

In the semiconductor device configured in this manner, the cross-sectional area of the suspension lead 3 connected to the element mounting portion 2 is formed to be small, so that the interface with the resin package 7 is reduced compared to the conventional one. Reduces stress when cutting the hanging lead. Furthermore, even when stress is applied to the suspension lead 3, moisture and ionic impurities may pass through the interface between the suspension lead 3 and the resin package 7 and cause the resin package 7 to leak.
In particular, it is possible to suppress intrusion into the element mounting part 2,
Corrosion etc. in internal semiconductor elements can be prevented.

Moreover, even if the part 3a of the suspension lead 3 is formed thin,
Since the resin package 7 is supported using the auxiliary suspension lead 8, even if the suspension lead 3 is damaged during the lead frame cutting process, the resin package 7 can be supported by the auxiliary suspension lead 8, and the resin package 7 It is possible to prevent the relative movement of the mold and the interference between the mold and the package, thereby preventing damage to the package and the mold.

In this embodiment, the width dimension of the part 3a of the suspension lead 3 is reduced in order to reduce the cross-sectional area. However, by half-etching this part and reducing its thickness, the cross-sectional area can be reduced. It may also be reduced. Further, if space is available, two or more auxiliary suspension leads can be provided.

〔Effect of the invention〕

As explained above, the present invention makes the cross section of a part of the suspension lead that directly supports the element mounting part small, and
Since the auxiliary suspension lead is protruded from the frame at a position adjacent to the suspension lead, it is possible to prevent accidents such as corrosion and leakage of semiconductor elements due to the intrusion of moisture etc. through the interface between the suspension lead and the resin package. In addition, it is possible to strengthen the support of the resin package and prevent interference with a mold or the like during cutting, thereby preventing damage to the resin package.

[Brief explanation of drawings]

Fig. 1 is a plan view of the lead frame of the present invention, Fig. 2 is a front view of the semiconductor device after resin molding, Fig. 3 is a plan view of a conventional lead frame, and Fig. 4 is a front view of the semiconductor device after resin molding. It is. 1.11... Lead frame, 2, 12... Element mounting part, 3, 13... Suspension lead, 3a... Part (portion with reduced width), 4.14... External lead-out lead ,
5゜15...Tie bar, 6.16...Frame part,
7.17... Resin package, 8... Auxiliary hanging lead. Figure 1

Claims (1)

[Claims] 1. A lead frame for a semiconductor device in which an element mounting part is supported by a frame part using a suspension lead, and a region including the element mounting part is sealed with a resin package,
The suspension lead has a small cross section at least at a portion corresponding to the area between the frame portion and the outer portion of the resin package, and an auxiliary suspension lead whose tip reaches the resin package is provided at a position adjacent to the suspension lead. A lead frame for a semiconductor device, characterized in that a lead frame is provided protruding from the frame portion. 2. A lead frame for a semiconductor device according to claim 1, wherein the hanging lead has a width smaller at a portion between the frame portion and the outer portion of the resin package than at other portions.