JPH0579174B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lead fixing means for a lead frame in a semiconductor device.

[Conventional technology]

A semiconductor device is a semiconductor device in which a semiconductor element is mounted on a lead frame, as described in, for example, Japanese Patent Application Laid-Open No. 59-96758, Japanese Patent Application Laid-Open No. 59-130451, and Japanese Patent Application Laid-Open No. 59-175753. The external leads of the lead frame are electrically connected by bonding, and then sealed with resin to complete the process.

This lead frame, as shown as a in FIG. 4, is made of a conductive metal plate made of copper or nickel-iron alloy, etc., formed into a desired pattern shape by pressing, etching, or the like. The lead frame strip is divided into a plurality of unit frame regions, and the same pattern is formed in each region. A pad c is placed in the center of each area,
It is also connected to and supported by the tie bar d by a support bar e. Further, a large number of leads are arranged around the pad c, and each lead is connected to the tie bar d and the side rail b. The lead is divided into an inner lead f on the inside of the tie bar d and an outer lead g on the outside.

In order to manufacture the above-mentioned semiconductor device using this lead frame a, a semiconductor chip is mounted on the pad c, and the inner lead f and the pad c are connected with a bonding wire (not shown). Furthermore,
The semiconductor chip and bonding wires are sealed with resin and completed. The leads, particularly the inner leads, are deformed during handling during the plating process, wire bonding process, and molding process.

To prevent this deformation, for example,
As described in the above publication, it has been proposed to attach a heat-resistant insulating resin tape such as polyimide tape onto the leads. This method has been further developed to perform bonding molding by cutting the insulating resin tape h into a rectangular shape, or dividing it into pieces as appropriate and pasting them near the tips of the leads.

[Problem that the invention seeks to solve]

However, when fixing the leads with such insulating resin tape, the tape itself shrinks due to heating during lead bonding, and the lead part is strongly attracted to it, resulting in lead deformation (shifting). occurs, and the effect of preventing lead deformation cannot be fully exhibited. This phenomenon may pose a problem in terms of quality assurance in high-capacity semiconductor devices having a large number of leads.

The present invention has been made in view of the above-mentioned circumstances, and its object is to find a means for preventing deformation due to temperature rise when fixing leads with an insulating resin tape.

[Means for solving problems]

The present invention includes a pad having a substantially square planar shape for mounting a plurality of leads and a semiconductor element, and a tie bar connecting the leads so as to surround the pad, and a tie bar connecting the leads to each other so as to surround the pad. The lead frame is provided with a retaining tape developed around the pad, the retaining tape having a symmetrical flat trapezoidal shape with a lower base approximately the same length as one side of the pad; Holding tapes are placed corresponding to the corners of the pad so that their bottom bottoms are orthogonal to the diagonal line of the pad, and each of the four holding tapes is placed so that the four sides of the pad are parallel to the bottom of the pad. The present invention is characterized in that the left and right oblique sides are arranged along the bottoms of the four holding tapes corresponding to the corner portions.

〔Example〕

FIG. 1 is a plan view showing the main parts of the lead frame of the present invention. As in the conventional example, the lead frame has pads c, tie bars d, support bars e, inner leads f, and outer leads between side rails b on both sides. A lead g is formed respectively.

The pad c has a substantially square planar shape, and a total of eight holding tapes 1 are arranged around it and pasted on its upper surface so as to connect all the inner leads f to each other.

The holding tape 1 has a flat trapezoidal shape,
It is cut symmetrically so that the oblique sides have the same shape. As shown in FIG. 2, the length of the trapezoidal bottom 21 of the four first holding tapes 2 arranged parallel to the four sides of pad c is approximately equal to the length of the sides of pad c. It has a shape. Further, the lower bottoms 31 of the four second holding tapes 3 disposed at positions corresponding to the corner portions of the pad c are slightly shorter than the first holding tapes 2. As shown in FIG. 3, the second retaining tape 3 is arranged so that the lower base 31 is perpendicular to the extension x of the diagonal line of the pad c, that is, at a 45 degree angle to the first retaining tape 2. placed at an angle.

Due to the shapes of the first and second holding tapes 2 and 3 and their mutual arrangement, all the inner leads f are connected to each other by the first and second holding tapes 2 and 3. Then, an arrangement is obtained in which the distances between the tips of each inner leads f and the joining positions of the first and second holding tapes 2 and 3 are relatively equal.

As a result of the above, a large number of inner leads f are restrained and held by the eight first and second holding tapes 2 and 3, so deformation of the first and second holding tapes 2 and 3 due to thermal effects is also prevented. Thus, deformation of the inner lead f is suppressed.

〔Effect of the invention〕

According to the present invention, lead deformation can be effectively prevented without changing the holding process itself using the holding tape, and thereby,
The yield rate of semiconductor devices will also improve.

[Brief explanation of drawings]

1 to 3 are diagrams showing an embodiment of the present invention, and FIG. 4 is a diagram showing a conventional example. 1: Holding tape, 2: First holding tape, 3:
second retention tape, 21: bottom bottom, 31: bottom bottom,
a: lead frame, b: side rail, c: pad, d: tie bar, e: support bar, f: inner lead, g: outer lead, h: insulating resin tape.

Claims (1)

[Scope of Claims] 1. A pad having a substantially square planar shape for mounting a plurality of leads and a semiconductor element, and a tie bar connecting the leads so as to surround the pad, wherein the tie bar and the pad are connected to each other. The lead frame is provided with a retaining tape spread around the pad, the retaining tape having a symmetrical flattened trapezoidal shape with a lower base of approximately the same flow as one side of the pad. , four pieces of holding tape are arranged corresponding to the corner portions of the pad so that their lower bases are orthogonal to the diagonal of the pads, and the four sides of the pads and the lower bases are parallel to each other. A lead frame characterized in that the respective left and right oblique sides are arranged along the bottoms of four holding tapes corresponding to the corner portions.