JPH02308563A - Lead frame - Google Patents

Abstract

PURPOSE:To assure the mounting of a large chip by reducing a bonding distance between an inner lead and a semiconductor chip mounted on the former and securing bonding and further making the bonding part approach a bonding surface between the bonding part and the chip by rendering bonding processing to the inner lead. CONSTITUTION:A bonding part 10a is disposed outwardly to a rail 20, and a semiconductor chip 14 is placed on an inner lead 10 through an insulating sheet 16. A half cut part 22 bent by half cutting is formed on the basis of the bonding part 10a. Thereupon, the cut part 22 is yielded by sharing a lead frame plate material up and down, and a step A is formed up to about 2L/3 with frame plate thickness L. The upper surface of the bonding part 10 is made higher by the step A than the lead upper surface to make the bonding surface of the chip 14 approach the bonding part 10a of the lead 10.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a chip-on-lead type lead frame.

(Prior Art) Chip-on-lead type lead frames are different from commonly used lead frames in that they do not have a stage section for bonding semiconductor chips. An example of this is shown in Fig. 3. In Figure 6, which has the shape shown, 10 is an inner lead and 12 is an outer lead.

The bonding portion at the tip of the inner lead 10 is arranged to face the rail, and the other end of some of the inner leads extends near the center of the lead frame.

The semiconductor chip is mounted on an electrically insulating sheet attached to the inner leads extending near the center. The semiconductor chip and the inner leads 10 are connected by wire bonding as in the conventional case, and after wire bonding, the parts other than the outer leads 2 are sealed with resin.

This chip-on-lead type lead frame has the advantage of being able to easily secure a large mounting area in the center of the lead frame, so that a large semiconductor chip can be mounted thereon.

(Problems to be Solved by the Invention) In the chip-on-lead type lead frame, as described above, the semiconductor chip is placed on the lead frame via an insulating sheet. ! However, wire bonding is performed between the semiconductor chip and the inner leads, but when the semiconductor chip is mounted on the lead frame, the bonding surface of the semiconductor chip is higher than the bonding part of the inner leads, so the bonding surface of the semiconductor chip is higher than the bonding part of the inner leads. There are problems in that the distance between the leads and the bonding surface becomes long, and the wires hit the surface of the semiconductor chip, causing short-circuits and other defects.

Therefore, the present invention has been made to solve the above problems, and its purpose is to bring the bonding part of the inner lead closer to the bonding surface of the semiconductor chip, and to shorten the length of the bonding wire. It is an object of the present invention to provide a lead frame which can perform wire bonding more reliably without causing short-circuit defects.

(Means for solving problems) The present invention has the following configuration to achieve the above object.

That is, the chip-on-lead type lead is equipped with an inner lead on which a semiconductor chip is mounted via an insulating sheet having electrical insulation properties, and a bonding portion is provided at the tip of the inner lead exposed outside the insulating sheet. In the frame, the base portion of the bonding portion is bent to form the bonding portion at a height higher than that of the inner lead. Further, as the bending process, a half-cut process in which the inner lead is processed in a shearing manner is effective.

(Function) By bending the base of the bonding part of the inner lead and forming a height position of the bonding part higher than that of the inner lead, the bonding surface of the semiconductor chip and the bonding part of the inner lead The bonding distance between the semiconductor chip and the inner leads can be shortened.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described based on the accompanying drawings.

FIG. 1 is a cross-sectional view showing a state in which a semiconductor chip is bonded to a lead frame according to the present invention. In FIG. An insulating sheet 18 having electrical insulation property, a semiconductor chip 14 and an inner lead 1
This is a wire that connects between 0 and 0. The insulation sheet 16
is the inner lead 10 where the semiconductor chip 14 is +1m
In order to provide electrical insulation between the semiconductor chip 14 and the inner lead 10, the semiconductor chip 14 is pasted over the entire mounting range of the inner lead 10, except for the bonding portion 10a at the tip of the inner lead 10.

FIG. 3 is a plan view showing the overall shape of the lead frame of the embodiment, and the bonding portion 10a is disposed facing outward facing the rail 20 as shown in the figure. The semiconductor chip 14 is placed on the inner leads 10 with an insulating sheet 16 in between.

In FIG. 1, 22 is the bonding part 1 of the inner lead 10.
This is a half-cut portion formed by bending the base of 0a by half-cut processing. This half-cut portion 22 is formed by processing the plate material of the lead frame by vertically shearing it, and when the plate thickness of the lead frame is L, it is 2L73.
The step A can be formed to a certain extent. This results in
The upper surface of the bonding portion 10a is formed higher than the upper surface of the inner lead 10 by one step difference A.

In this way, by increasing the height of the bonding part 10a, the bonding surface of the semiconductor chip 14 and the bonding part 10a of the inner lead 10 can be brought closer to each other, so the wire bonding distance can be shortened, and short-circuit defects can be eliminated to ensure accurate bonding. Can be wire bonded to.

In the half-cut process, the inner leads are sheared vertically as shown in the figure, so there is almost no length of the bent portion in the longitudinal direction of the inner leads, and the semiconductor chip 14 can be moved closer to the bonding part 10a. It becomes possible to place.

Note that since the lower surface of the bonding portion 10a is higher than the lower surface of the inner lead, wire bonding is preferably performed using a jig that supports the lower surface of the bonding portion 10a.

FIG. 2 shows another embodiment of the lead frame. In this example, the base of the bonding part 10a is bent to form the height of the bonding part 10a higher than that of the inner lead 10. ing. In the case of this embodiment as well, since the bonding portion 10a is formed close to the bonding surface of the semiconductor chip 14, the bonding distance can be shortened, and during wire bonding, the wire hits the surface of the semiconductor chip and short circuits occur. Problems such as occurrence of defects can be solved.

Note that when comparing the above embodiments, when the inner lead 10 is half-cut as shown in FIG.
Since the length of the bent portion B of the inner lead shown in the figure can be shortened, a larger semiconductor chip can be mounted accordingly, and the distance between the bonding portion 10a and the semiconductor chip can be further reduced, which is more effective.

The operation of bending the inner lead as described above is
As long as it is a chip-on-lead type lead frame, the lead pattern, such as the number of leads and the shape of the leads, is not particularly limited, and lead frames having various lead patterns can be similarly applied.

The present invention has been variously explained above with reference to preferred embodiments, but the present invention is not limited to these embodiments and can of course be modified in many ways without departing from the spirit of the invention. That's true.

(Effects of the Invention) According to the lead frame of the present invention, as described above, by bending the inner leads, the bonding distance between the inner leads and the mounted semiconductor chip can be shortened, and It becomes possible to perform wire bonding more accurately. In addition, when the inner lead is half-cut to form the bonding part at a higher position, the bonding part of the inner lead and the bonding surface of the semiconductor chip can be brought closer together, and the bonding distance can be shortened. It has great effects such as being able to mount large semiconductor chips.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of a lead frame according to the present invention, FIG. 2 is a sectional view showing another embodiment, and FIG. 3 is a plan view showing the overall shape of the lead frame. DESCRIPTION OF SYMBOLS 10... Inner lead, 10a... Bonding part, 12... External lead, 14... Semiconductor chip, 16... Insulating sheet, 18... Wire, 20... Rail.

Claims (1)

[Claims] 1. An inner lead on which a semiconductor chip is mounted via an insulating sheet having electrical insulation properties, and
In a chip-on-lead type lead frame in which a bonding portion is provided at the tip of the inner lead exposed to the outside of the insulating sheet, the base of the bonding portion is bent to adjust the height position of the bonding portion to the inner lead. A lead frame characterized by being formed at a higher position than the height position. 2. The lead frame according to claim 1, wherein the bending process is a half-cut process in which the inner lead is sheared.