JPH01251748A - Lead frame for semiconductor device - Google Patents

Abstract

PURPOSE:To make a mounting part nearly completely flat irrespective of a size of the mounting part of a lead frame by a method wherein the mounting part has more than one narrow groove extended in the direction nearly perpendicular to the initial curvature direction on its rear and a curvature of the mounting part is corrected as required. CONSTITUTION:In a lead frame 1, a mounting part 3 for mounting a semiconductor chip is formed in the center; its both ends are supported individually by a metal sheet 2 via support leads 4. Two or more narrow grooves 15 in the direction nearly perpendicular to the width direction of a metal sheet 12 are made on the rear of the mounting part 13 over its whole width so as to be separated from each other. Then, the lead frame where the narrow grooves 15 have been made on the rear of the mounting part 13 is plated in a required part during a plating process; during a DP working operation, a curvature of the mounting part 13 is corrected completely by using a whole-face punching metal mold. As a result, it is possible to obtain the lead frame, for semiconductor device use, where the surface of the mounting part 13 for mounting the semiconductor chip is nearly completely flat.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a lead frame for a semiconductor device in which a semiconductor chip mounting portion has excellent flatness.

(Prior art) When placing a semiconductor device, such as a semiconductor chip such as an IC or LSI, on the surface of a mounting portion of a lead frame, if the surface of the mounting portion is warped, it may cause poor adhesion to the semiconductor chip. becomes. Therefore, the surface of the receiver must be as flat as possible. In particular, the flatness of the mounting part is becoming more and more important as the chip size increases with the high integration of semiconductor devices such as LSIs and the lead frame mounting part becomes larger accordingly. FIGS. 2 and 3 illustrate lead frames for semiconductor devices and the warping of their mounting parts. Each lead frame l is continuously attached to a long metal sheet 2 of a constant width as shown in the figure. It is formed. This lead frame 2 has a mounting section 3 in the center for mounting a semiconductor chip, and both ends of the mounting section 3 are supported by the metal sheet 2 via support leads 4, respectively. In addition, the mounting section 3
A large number of external leads 5 are also formed on both sides. By the way, as shown in FIG. 3, the mounting portion 3 of the metal sheet 2 generally tends to have a large warpage "a" in the width direction of the metal sheet 2.

The cause of the warping of the mounting portion of the lead frame may be something that is originally present in the lead frame material itself, or may occur during a subsequent processing step such as a plating step.

Therefore, conventionally, as a means to prevent or correct the warpage of the mounting portion of the lead frame, it is necessary to reduce the press pressure on the mask as much as possible when plating, that is, when partial plating is performed by pressing the mask against the lead frame. Alternatively, the bending process (hereinafter referred to as DP processing) for the support lead of the support lead may be performed using a mold for stamping the entire surface of the support lead (i.e., one that applies even press pressure to the entire surface of the support lead). However, if the dimensions of the mounting portion are large, curling cannot be sufficiently prevented or corrected.

(Problem to be Solved by the Invention) Therefore, the present invention provides a semiconductor device that can achieve almost complete flattening of the mounting portion of a lead frame, regardless of the size of the mounting portion. The purpose is to provide lead frames for

(Means for Solving the Problems) As a means for solving the above problems, the present invention provides a mounting section for mounting a semiconductor chip on a surface, and a mounting section support lead for supporting the mounting section. , in a lead frame for a #P conductor device comprising a large number of external leads arranged around the mounting part, the mounting part is arranged on the back surface thereof in a direction substantially perpendicular to the original anti-reverse direction. The present invention provides a lead frame for a semiconductor device, which has one or more elongated narrow grooves, and, if necessary, the warpage of the mounting portion is corrected by a mold for stamping the entire surface of the mounting portion. be.

(Example) Hereinafter, the present invention will be explained with reference to the illustrated embodiments.

FIG. 1 shows a lead frame for a semiconductor device according to the present invention with its mounting portion as the center, and in this figure, the mounting portion z3 is shown with its back surface facing upward. This mounting portion 13 is supported at both ends by a metal sheet 12 via a pair of support leads 14, as in the case of FIG. The other configurations are the same as those of the conventional one, and any configuration can be used. As shown in the figure, a plurality of narrow grooves are formed on the back surface of the placing part Z3 in a direction substantially perpendicular to the original curling direction of the placing part 13 (i.e., the width direction of the metal sheet Z2) as shown in the figure. I5 are bored apart from each other. The width of this narrow groove I5 is generally 130 to 220 mm.
The μm1 depth is generally preferably 100 to 170 μm. Although there is no particular restriction on the number of narrow grooves, it is generally preferred that the number be 5 or more.

There is no particular restriction on the method of forming the thin f/1j 15 on the back surface of the mounting part 13, but in the process of etching the metal sheet for forming the mounting part 13, external leads, etc., etching ( half-etching) is desirable.

The lead frame with the thin strips 815 formed on the back surface of the mounting part 13 is then plated in the required part in a plating process, and then a mold is used to punch the entire surface of the mounting part I3 during DP processing. As a result, a lead frame for a semiconductor device can be obtained in which the surface of the mounting portion 13 on which a semiconductor chip is to be mounted is completely flat.

Example 1 A long sheet of copper alloy for a lead frame having a thickness of 0.25 m was etched to form a lead frame having a length of 50B1 width IQ and a mounting portion of 51B. At the same time as this etching process, a width of 0.22
Seven narrow grooves of 1B and a depth of 0.17111 were formed with an interval of group 8 over the entire width in the width direction of the mounting section. As a result of this etching process, the mounting part of the lead frame obtained is warped 1a"
(See FIG. 2) was 18 μm to 30 μm.

Next, after gold plating the required portions of the lead plate surface, we performed DP processing on the supporting leads using a mold for stamping the entire surface of the mounting section.As a result, the warpage "a" on the surface of the mounting section was almost zero. It was hot.

(Effects of the Invention) As described in detail above, in the present invention, a narrow groove is formed on the back surface of the placing part of the lead frame of the conductor device in a direction substantially perpendicular to the original warping direction, and then, the placing part is supported. Since the bending of the lead is corrected at the same time as the warping of the placing part, it has become possible to significantly improve the flatness of the placing part. Furthermore, in the manufacture of the lead frame of the present invention, the formation of the narrow grooves on the back surface of the mounting part is carried out at the same time as the etching process of the external leads, etc., so there is no need for a separate process for correcting warpage, and therefore there is no need for a separate process for warping, and therefore there is no need for manufacturing. It will be advantageous.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a lead frame for a conductor device according to the present invention, Fig. 2 is a plan view of a metal sheet forming the lead frame, and Fig. 3 is a view of Fig. 2 for explaining warping of the lead frame. [It is a cross-sectional view along the 1-m line. In the diagram! ...Lead frame, 2...Metal sheet,
3... Placement part, 4... Support lead, 5... External lead, 12... Metal sheet, I3... Placement part, 1
4...Support lead, 15...Harrow. Applicant's agent Patent attorney Takehiko Suzue Engraving of drawings (
(No change in content) Figure 1 Procedural amendment dated September 9, 1986 Kunio Ogawa, Commissioner of the Patent Office 1, Indication of case Patent application No. 1988-78849 2, Title of invention Lead frame for semiconductor device 3, Amendment Patent applicant (319) Toppan Printing Co., Ltd. 4, Agent 3-7-2 Kasumigaseki, Chiyoda-ku, Tokyo 1j BE Pill 〒1
()G Telephone 03 (502> 3181 (Main)
S. Full text of the specification subject to amendment, Drawing 7, Contents of amendment

Claims (2)

[Claims] (1) A mounting section for mounting a semiconductor chip on the surface;
In a lead frame for a semiconductor device comprising a mounting part support lead supporting the mounting part and a large number of external leads arranged around the mounting part, the mounting part is located on the back surface of the lead frame. A lead frame for a semiconductor device, characterized in that the lead frame has one or more narrow grooves extending in a direction substantially perpendicular to the original direction of warpage, and the warpage of the mounting part is corrected by a mold for stamping the entire surface of the mounting part. . (2) a mounting section for mounting the semiconductor chip on the surface;
In a lead frame for a semiconductor device comprising a mounting part support lead supporting the mounting part and a large number of external leads arranged around the mounting part, the mounting part is located on the back surface of the lead frame. A lead frame for a semiconductor device having one or more narrow grooves extending in a direction substantially perpendicular to an original warping direction.