JPH05138281A - Manufacture of read frame with heat sink - Google Patents

Abstract

PURPOSE:To manufacture the lead frame with the heat sink having the thin sheet part which is become to the lead part in four directions of the thick plate to be made to the heat sink part. CONSTITUTION:Lead parts 12b are formed on the circumference of the heat sink part 12a by rolling the metal plate 12 with the the roll with grooves continuously having almost half circle like grooves 10a to the circumferential direction and the roll with projects continuously having projecting parts 11a for rolling the metal plate to be rolled 12 with the prescribed roll reduction, forming the recessed parts 11b of the dimension corresponding to the heat sink part 12a to be formed on either of the outer circumference of projecting part 11a of the roll with projection 11 or the inner circumference of groove parts of the roll 10 with grooves by the prescribed interval to the circumferential direction, and rolling the heat sink part 12a with the recessed parts 11b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame material for forming a lead frame, and more particularly to a method for manufacturing 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 output 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. Therefore, it is considered that a heat sink excellent in heat dissipation is embedded in the semiconductor package.

As an example of this, there is a modified section strip, which is used as a lead frame material for transistors.

FIG. 4 is an external perspective view of a conventional modified cross-section strip of this type.

As shown in the figure, the modified cross-section strip 1 is not a single plate-shaped member, but is a plate-shaped member formed so that the center has a thicker step than both ends in the width direction. A semiconductor chip is mounted on the thick plate portion 2 at the central portion, and lead portions are formed on the thin plate portions 3 at both ends and embedded in the package.

As a method of manufacturing such a modified cross-section strip, a V-die having a die groove having a side clearance angle in the molding direction and a flat roll are used, and the thickness of each part of the modified cross-section strip at the time of final molding. A material strip having a cross-section with a thickness ratio that is almost the same as the thickness ratio is extruded and then finish-rolled with a hole-type roll, and a plurality of grooved rolls each having a shape gradually changed in the rolling direction are arranged. There is a method of roll-forming a modified cross-section strip with these roll groups.

[0007]

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. The thick plate portion is used as a heat sink and the thin plate portion is external. It is used as a lead portion for connection with a 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, it cannot be used as a lead frame material for an IC having a large number of signal terminals because the number of pins is insufficient with leads on only one side or both sides of the heat sink portion. ..

As a lead frame material for a multi-pin IC having a large number of signal terminals, it is necessary to secure the lead portions in four directions of the heat sink portion. That is, it is necessary to provide a lead frame having thin plate portions that serve as lead portions on four sides of the thick plate portion that serves as a heat sink.

On the other hand, in the above-described conventional method for producing a modified cross-section strip using a grooved roll, it is possible to form continuous thin plate portions on both sides of the strip material, but the heat sink portion is formed. It is not possible to intermittently form the thick plate portion that functions as the longitudinal direction of the strip.

As a method for manufacturing a lead frame material having lead portions in four directions, a conventional method is used to form a modified cross-section strip having thin plate portions continuously on both sides of the strip material in the longitudinal direction, and then a thick plate portion. It is conceivable to divide the same by cutting to form the lead portions on both sides in the longitudinal direction, but the yield is deteriorated and cutting scratches remain on the surface of the lead frame, which is not suitable for a lead frame material in terms of quality.

Therefore, an object of the present invention is to solve the above problems and to manufacture a lead frame material with a heat sink having thin plate portions to be lead portions in four directions of a thick plate portion to be a heat sink portion. It is to provide a manufacturing method of.

[0012]

In order to achieve the above object, the present invention provides a grooved roll having substantially semicircular groove portions continuously in the circumferential direction, and rolling at a position corresponding to the groove. While rolling the plate-shaped member with a convex roll having a convex portion for rolling the power plate-shaped member at a predetermined rolling reduction in a circumferential direction, the outer periphery of the convex portion of the convex roll and the grooved roll By forming recesses of any size on the inner circumference of the groove portion in the circumferential direction at predetermined intervals according to the heat sink portion to be formed and rolling the heat sink portion with the recess portions, the lead portion is provided around the heat sink portion. Is formed.

[0013]

According to the above structure, when the plate member is pressed between the substantially semicircular groove portion and the circumferentially continuous convex portion, both sides of the plate member are deformed in the width direction, Deformation in the longitudinal direction is likely to occur in the portion of the plate-shaped member corresponding to the recess, and the material pool is absorbed in this recess by being compressed into the recesses arranged at predetermined intervals with a predetermined reduction ratio. Since the strip-shaped member is smoothly rolled, the lead portion can be formed around the heat sink portion, and the workability is improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a principle view of a rolling apparatus to which the method for manufacturing a lead frame material with a heat sink according to the present invention is applied, and FIG. 2 is a partial sectional view taken along the line AA of the apparatus shown in FIG.

In FIG. 1, a grooved roll 10 and a convex roll 11 are arranged such that their rotation axes are parallel to each other (the rotation axis is perpendicular to the plane of the drawing) and face each other, and a metal plate 12 as a plate-shaped member is in front. When inserted between the grooved roll 10 and the convex roll 11 (from the left side of the drawing), the metal plate 12 is rolled, and the thick plate portion 12a and the thin plate portion around the thick plate portion 12a (four sides) are formed. 12b is integrally formed and is discharged from the rear surface (right side in the figure).

The grooved roll 10, the circumferential surface, and this along the circumferential surface section is substantially semicircular (see Figure 2) circumferentially continuous groove 10a is formed, the arrows P ₁ Rotate in the direction.

The convex roll 11 has, on its circumferential surface, a convex portion 11a having a substantially semicircular cross section along the circumferential surface (see FIG. 2) and continuous in the circumferential direction. Rotate in ₂ directions. The position of the convex portion 11a on the convex roll 11 corresponds to the groove 10a, and the convex portion 11a and the groove portion 10
The distance to a is set so that the lead portion (thin plate portion 12b) can be formed by rolling a metal plate as a plate-shaped member to be rolled at a predetermined rolling reduction. Eight concave portions 11b are formed on the outer circumference of the convex portion 11a at predetermined intervals along the circumferential direction. The size of the recess 11b has a size corresponding to the heat sink part (thick plate part 12a) to be formed.
Although the number of the concave portions 11b is eight in the figure, it is not limited to this.

Although the cylindrical portion 10c of the grooved roll 10 and the cylindrical portion 11c of the convex roll 11 are not directly related to the rolling of the metal plate 12, the surface speeds in the circumferential direction are different, so that if they come into contact with each other, both rolls 10c. , 11 are formed so as to be separated from each other because they act to prevent the rotation of 11 and 11.

The material of the grooved roll 10 and the convex roll 11 is harder than that of the metal plate 12, and the width of the metal plate 12 does not protrude in the width direction from between the groove portion 10a and the convex portion 11a when rolled. Needless to say, it is such a length.

Next, the operation of this embodiment will be described.

FIG. 3 is an external perspective view of a lead frame member with a heat sink formed by the apparatus of this embodiment after being flattened.

In FIG. 1, the groove portion 1 of the grooved roll 10 is shown.
0a and the convex portion 11a of the convex roll 11 with an arrow P ₃
When the tip portion of the metal plate 12 is inserted in the direction, the metal plate 12 is rolled up and rolled into a substantially semi-cylindrical shape as shown in FIG. 2 at the groove portion 10a and the convex portion 11a and conveyed to the right side of the drawing.

At this time, since both side portions (12b) of the metal plate 12 in the width direction are restrained by the outer surface of the convex portion 11a and the inner surface of the groove portion 10a, deformation in the width direction is likely to occur. On the other hand, in the vicinity of the recess 11b of the metal plate 12, the metal plate 12 is more likely to be deformed in the longitudinal direction than in both side portions. For this reason, if rolling is continued to the same plate thickness as both side portions, a material pool will be generated. However, in the apparatus of the present embodiment, there is a recess 11b that periodically forms the thick plate section 12a, so that the material pool is formed. By absorbing and compressing the metal plate 12 into the concave portion 11b, the metal plate 12 is smoothly rolled, so that the lead portion is formed around the heat sink portion. The metal plate 12 thus obtained is flattened and, if necessary, subjected to a process such as slitting to adjust the width dimension, whereby a lead frame material with a heat sink as shown in FIG. 3 is obtained.

Next, the present embodiment will be described with specific numerical values, but the present invention is not limited to these numerical values.

Using a convex roll 11 having a convex portion 11a having a radius of curvature of about 13 mm and a grooved roll 10 having a groove portion 10a corresponding to the convex roll 11, a thickness of about 0.75 mm and a width of about 25 mm are used. The oxygen-free copper strip annealed material of was rolled as a metal plate 12. The distance between the convex portion 11a and the groove portion 10a is set to about 0.2 mm, and the outer diameter of the convex portion 11a is about 10 mm × 10 mm and the depth is about 1.0 m.
Recesses 11b of m are formed at intervals of 60 mm in the circumferential direction. The obtained lead frame material had a width of about 40 mm, a thick plate portion 12a having a thickness of about 1.0 mm, and a thin plate portion 12b having a thickness of about 0.2 mm, and no abnormality such as twisting or cracking occurred. This lead frame material was flattened by a flat roll and slitted to have a width of about 30 mm to obtain a lead frame material with a heat sink as shown in FIG.

As described above, according to the present embodiment, the grooved roll 1 having the substantially semicircular groove portion 10a continuously in the circumferential direction.
0 and a convex roll 11 having a continuous convex portion 11a for rolling the metal plate 12 to be rolled at a predetermined reduction ratio in the circumferential direction at a position corresponding to the groove 10a. While rolling, the convex portion 11a of the convex roll 11
Recesses 11b having a dimension corresponding to the heat sink 12a to be formed are formed at predetermined intervals in the circumferential direction on either the outer circumference of the groove or the inner circumference of the groove of the grooved roll 10.
Since the lead portion 12b is formed around the heat sink portion 12a by rolling the heat sink portion 12a with, the lead frame material having the thin plate portion serving as the lead portion in four directions around the thick plate portion serving as the heat sink can be processed. It is possible to obtain a lead frame material with a heat sink for an IC having a large number of pins, and moreover, since the processing step is by rolling, the surface quality is excellent and the productivity is high,
Moreover, workability is improved.

In this embodiment, the concave portion 11b is replaced by the convex portion 11b.
Although it is formed in a, the recess 11b may be formed in the groove 10a without being limited to this.

[0029]

In summary, according to the present invention, deformation in the width direction is likely to occur on both sides of the plate-like member, and deformation in the longitudinal direction is likely to occur in the recess, so that no material accumulation occurs and the plate is recessed into the recess. Since the plate-shaped member is reasonably rolled by the compression of the plate-shaped member, it is possible to process a lead frame material having a thin plate portion serving as a lead portion in four directions around a thick plate portion serving as a heat sink. A large number of lead frame materials with heat sinks for ICs can be obtained, and since the working process is by rolling, the surface quality is excellent, the productivity is high, and the workability is improved.

[Brief description of drawings]

FIG. 1 is a principle view of a rolling apparatus to which a method for manufacturing a lead frame material with a heat sink according to the present invention is applied.

FIG. 2 is a partial cross-sectional view taken along the line AA of the rolling device shown in FIG.

FIG. 3 is an external perspective view of a lead frame material with a heat sink formed by the apparatus of this embodiment after being flattened.

FIG. 4 is an external perspective view of a conventional modified cross-section strip.

[Explanation of symbols]

 10 Roll with groove 10a Groove part 11 Roll with convex 11a Convex part 11b Recess 12 Metal plate

Claims (1)

[Claims] 1. A grooved roll having a substantially semicircular groove portion continuously in the circumferential direction, and a projection for rolling a plate member to be rolled at a predetermined rolling reduction at a position corresponding to the groove. A plate member is rolled with a convex roll having a continuous portion in the circumferential direction, and a heat sink portion to be formed on either the outer circumference of the convex portion of the convex roll or the inner circumference of the groove portion of the grooved roll. Of the lead frame material with a heat sink, characterized in that the lead portion is formed around the heat sink portion by forming the recess portion having a dimension corresponding to the above at a predetermined interval in the circumferential direction and rolling the heat sink portion in the recess portion. Production method.