JPH07284873A - Manufacture of lead frame material having heat sink - Google Patents

Abstract

PURPOSE:To easily obtain a lead frame having heat sink in good precision by repeating in plural times the rolling process to form a thin sheet part to be used for a lead part by the circumference of a caliber. CONSTITUTION:In the first step rolling process, a caliber 51 is formed at the prescribed interval in a caliber roll 5, together with a lower side flat roll 7, a stock 8 is formed to an intermediate rolled stock 9 having a thick sheet part 91 and thin sheet part 93 thereabout. In the subsequent second step rolling part, the intermediate rolled stock 9 is formed to a lead frame stock 4 having heat sink by the caliber roll 6, in which a caliber 61 smaller than the caliber 51 of the first caliber roll 5 is formed, and the lower side flat roll 7. At this time, the caliber 61 is of the same size as the dimension corresponding to the thick sheet part 41 of the lead frame stock 4 having heat sink. By this method, the lead frame stock having heat sink for IC with many pins can be easily obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a lead frame material for forming a lead frame, particularly a lead frame material with a heat sink.

[0002]

2. Description of the Related Art Since the amount of heat generated from a semiconductor increases as the speed and integration of the semiconductor increase, it is necessary to dissipate the heat to the outside in order to prevent the performance of the semiconductor from being deteriorated by this heat. is there. Therefore, it is considered to embed a heat sink excellent in heat dissipation in the semiconductor package.

As an example of this, there is a modified cross section, which is used as a lead frame material for transistors. Figure 4
FIG. 6 is a perspective view showing the appearance of a conventional modified cross-section strip of this type. As shown in this figure, the modified cross-section strip 1 is not a single strip member, but is a strip member in which a thick plate portion 11 having a step in the width direction whose center is thicker than both ends and thin plate portions 12 on both sides are formed. Is. A semiconductor chip is mounted on the thick plate portion 11 at the central portion, and lead portions are formed on the thin plate portions 12 at both ends and embedded in the package.

As a method of manufacturing such a modified cross-section strip, a molding method of rolling and molding using a V-shaped die having a mold groove having a side clearance angle in the molding direction (longitudinal direction) and a flat roll, and a final method A method of extruding a material strip having a cross-section with a thickness ratio of each part of the modified cross-section strip at the time of forming, and then finish rolling with a hole-type roll, and a method of sequentially changing the shape in the rolling direction. There is a method of arranging grooved rolls and rolling-forming a modified cross-section strip by these roll groups.

FIG. 5 is a cross-sectional view for explaining a groove roll rolling method, which is one of the methods for rolling the profiled strip shown in FIG. 4 from a plate member. In this figure, by using a groove roll 2 and a flat roll 3 each having a groove 21 having an arbitrary groove angle θ and a corner radius R, the plate-shaped member 1 is pressed in the vertical direction of the drawing and is perpendicular to the paper surface. Transport in the direction. Since both edges of the groove 21 of the plate-shaped member 1 are rolling parts, the material deformation in the rolling part is not limited to the width direction of the plate-shaped member 1 (left-right direction in the figure), but also the groove inward direction (in the paper surface). Also in the vertical direction), the thin plate portion 12 rolled by the groove roll 2 and the flat roll 3 and the thick plate portion 11 not rolled by the groove 21 are integrally formed.

[0006]

However, the above-mentioned conventional modified cross-section strip is a lead frame material having a portion having a different plate thickness only in the plate width direction, and the thick plate portion 11 at the center is used.
Is used as a heat sink, and the thin plate portions 12 on both sides are used as leads for connection with an external connector. Therefore, in this modified cross-section strip, the lead portion is limited to one side or both sides of the heat sink portion. Therefore, although it can be used as a lead frame material for a transistor having a small number of terminals, as a lead frame material for an IC having a large number of signal terminals, the number of pins is insufficient for the leads on only one side or both sides of the heat sink portion. So it cannot be used.

[0007]

According to the present invention, a material is rolled on one of the roll peripheral surfaces at predetermined intervals along the peripheral surface by a work roll having a hole shape, and a heat sink portion is formed by the hole shape. Is a method for manufacturing a lead frame material with a heat sink, in which a rolling step of forming a thick plate portion that is to be formed and forming a thin plate portion that is to be a lead portion around a hole die is repeated a plurality of times. Further, it is a method for manufacturing a lead frame material with a heat sink, in which an annealing process is included in all or a part of the rolling process which is repeated a plurality of times.

[0008]

The rolling process for forming a thick plate portion around the roll and a thin plate portion around the roll material is repeated a plurality of times by rolling the material with a work roll having a hole shape at a predetermined interval on the circumferential surface of the roll. As a result, the thick plate portion and the thin plate portion having a predetermined size are formed, so that it is possible to efficiently produce a lead frame member with a heat sink having a heat sink portion and lead portions around the heat sink portion. Further, by including the annealing step, the surface quality of the lead frame material with heat sink can be improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 shows a structure of a lead frame with a heat sink which is an object of the present invention. That is, in the lead frame member 4 with a heat sink, the thick plate portion 41 is intermittently formed in the center, and the thin plate portions 42 and 43 are formed around this.

The entire rolling process for manufacturing such a lead frame material with a heat sink is shown in a side view of FIG. 1 and a part of the rolling process is shown in a perspective view of FIG. That is, the lower flat rolls 7 and 7 and the upper work rolls 5 and 6 are hole-type rolls having hole-shapes 51 and 61 corresponding to the thick plate portion 41 at their central portions. In the first rolling process on the left side, the hole dies 51 are formed on the hole roll 5 at a predetermined interval.
1 and an intermediate rolled material 9 having thin plate portions 92 and 93 around this 1 are formed by rolling. In the subsequent second-stage rolling section on the right side, intermediate rolling is performed by the lower-roller roll 6 and the lower-roller roll 6 in which the lower-roller die 61 of the first-roller roll 5 is formed. The material 9 is molded, and the lead frame material 4 with a heat sink is molded. At this time, the hole die 61 has the same size as that of the thick plate portion 41 of the lead frame member 4 with a heat sink. Further, the interval between the hole dies 61 of the second-stage hole roll 6 is adjusted so that the thick plate portion 91 of the intermediate rolled material 9 according to the first stage becomes the center of the hole 61 of the hole roll 6. is doing.

First, the hole type roll 5 as shown in FIG.
In the case of performing the rolling of the second stage, in the portion where the entire plate width of the raw material 8 is processed into the thin plate portion 93 and in the portion where the thick plate portion 91 is formed in the center and both sides are formed into the thin plate portions 92, the direction of deformation of the material is You need to be careful. In other words, there is no problem if the entire thin plate portion 93 is deformed in the longitudinal direction, but if the thin plate portions 92 on both sides are deformed in the longitudinal direction, they cannot be balanced with the thick plate portion 91 and the intermediate rolled material 9 Cracks and twists occur in the. Therefore, the material deformation in the thin plate portions 92 on both sides must occur in the plate width direction. In order to cause material deformation in the plate width direction, the hole die 51 of the hole roll 5 is provided with an appropriate groove angle θ and a corner curvature R as described in the prior art shown in FIG. .

However, if the width of the thin plate portions 92 on both sides is extremely widened or the workability is large, deformation in the longitudinal direction easily occurs and the rolling becomes unstable. Therefore, in FIG.
As shown in Fig. 5, the hole type roll 5 with the hole type size successively decreased
By gradually forming the thick plate portion 41 and the thin plate portions 42 and 43 which are required by using the above-mentioned and 6, it becomes possible to stably manufacture the lead frame member 4 with a heat sink.

Next, a concrete example will be described. An oxygen-free copper annealed material having a plate thickness of 0.95 mm and a plate width of 42 mm was first rolled by a hole-shaped roll 5 and a flat roll 7 as shown in FIG. The perforated roll 5 has an opening of 20 mm and a depth of 1.
A 2 mm hole die 51 is machined at a pitch of 31.0 mm. The side surface of the hole die 51 has a groove angle θ of 45 degrees and a corner radius R of 0.8 mm as shown in FIG. Has been formed. When the thin plate portion of the rolled material was rolled so as to have a plate thickness of 0.35 mm, the thick plate portion 91 showed an increase in thickness at the peripheral shoulder portion due to material deformation into the hole die, and the average plate thickness was 1.0.
It became 5 mm. The pitch of the rolled material was narrow in the whole thin plate portion and wide in both side thin plate portions.

Next, this rolled material was rolled by the second hole type roll 6 so that the thin plate portion had a thickness of 0.2 mm. The hole type 61 of the second hole type roll 6 has a depth of 0.8 mm.
At the side surface, the groove angle θ is 85 degrees, and the corner curvature R is 0.
It is formed with 2 mm. In the second hole type roll 6, since the thick plate portion is also slightly processed, the opening size is 15 × 14.8.
mm and the length in the circumferential direction are slightly reduced. When rolling was performed such that the center of the thick plate portion 91 formed by the first rolling coincides with the hole shape 61 of the second hole forming roll 6, the obtained rolled material has the dimension of the thick plate portion 41. Is 15 mm
The pitch was 40 mm, and there was no abnormality such as twisting or cracking. The rolled material was width-cut to a plate width of 40 mm, and a lead frame material 4 with a heat sink could be manufactured as shown in FIG.

For comparison, an attempt was made to directly roll the material used for the first rolling by the second hole-type roll 6, but if the thin plate portion is thinned (the workability is increased), both side thin plates will be thinned. When the degree of processing is increased, twisting occurs in the rolled material as a whole, and rolling becomes impossible. As described above, by performing rolling a plurality of times, it is possible to manufacture a stable lead frame material with a heat sink.

In the above embodiment, rolling in a two-step process has been described, but depending on the required dimensions of the thick plate portion and the thin plate portion, it is possible to carry out a rolling process of three steps or four steps and a plurality of times. is there. When the rolling process is performed a plurality of times, it is most efficient to continuously roll it as shown in FIG.
However, rolling the rolled material for each rolling step may be performed intermittently, and if a step of annealing the rolled material is added to all or part of each rolling step,
Further, the moldability can be improved.

[0017]

As described above, according to the method of manufacturing the lead frame member with the heat sink of the present invention, the lead frame member having the thin plate portions serving as the lead portions on the four sides of the thick plate portion serving as the heat sink is accurately processed. It is possible to easily obtain a lead frame member with a heat sink for an IC having a large number of pins, and further, because of the processing by rolling, the surface quality is good and the productivity is high.

[Brief description of drawings]

FIG. 1 is a side view showing the entire rolling process of an example,

FIG. 2 is a perspective view showing one rolling process,

FIG. 3 is a perspective view showing a lead frame material with a human sink manufactured by the main rolling process;

FIG. 4 is a perspective view showing the configuration of a conventional modified cross-section strip,

5 is a cross-sectional view showing a method for manufacturing the modified cross-section strip shown in FIG.

[Explanation of symbols]

 1 Deformed section strip 11 Thick plate part 12 Thin plate part 2 Groove roll 21 Groove 3,7 Flat roll 4 Lead frame material with human sink 41,91 Thick plate part 42,43,92,93 Thin plate part 5,6 Hole roll 51, 61 Hole type 8 Material 9 Intermediate rolled material

Claims (2)

[Claims] 1. A raw material is rolled on a peripheral surface of one of the rolls by a work roll having a hole shape at a predetermined interval along the peripheral surface, and a thick plate portion serving as a heat sink is formed by the hole shape, Further, the method for manufacturing a lead frame material with a heat sink, characterized in that a rolling step of forming a thin plate portion which becomes a lead portion around a hole is repeated a plurality of times. 2. A method for manufacturing a lead frame material with a heat sink, characterized in that an annealing step is included in all or a part of the rolling steps repeated a plurality of times according to claim 1.