JP3346212B2 - Method of manufacturing lead frame material with heat sink - Google Patents

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, and more particularly to a method for manufacturing a lead frame material with a heat sink provided with a heat sink for absorbing heat energy emitted from a semiconductor.

[0002]

2. Description of the Related Art Conventionally, a heat sink has been embedded in a semiconductor package for the purpose of heat dissipation of a semiconductor. As an example of this, a heat sink portion and a lead portion are integrated so as to have different thicknesses, and there is an irregular cross section (lead frame material with heat sink) as a lead frame material for a transistor. The irregularly shaped cross section has a thin portion provided on one or both sides in the plate width direction, and a thick portion provided in another region or the center.

[0003] As a method of manufacturing this irregularly shaped section, a V-shaped groove having a side clearance angle in the forming direction of the irregularly shaped section is provided.
A mold die and a rolling roll method for rolling a metal strip by a flat roll provided opposite thereto to produce a deformed cross section, having a cross section corresponding to the thickness ratio of each part of the final shape of the deformed cross section. A method of extruding a material strip, rolling the extruded material strip with a grooved roll corresponding to the shape of the deformed cross-section to produce a deformed cross-section, the thickness ratio of each part of the final shape of the deformed cross-section In order to correspond to the above, a plurality of grooved rolls whose shapes are changed little by little in the forming direction of the deformed cross-section strip are sequentially arranged, and the metal strip material is formed by the plurality of grooved rolls and the flat roll provided opposite thereto. Are rolled successively a plurality of times to produce a deformed cross-section strip.

In addition, with the recent increase in output and integration of semiconductors, there has been an increasing demand for a lead frame material with a heat sink which is excellent in heat dissipation and can sufficiently secure the number of lead pins. Instead of a lead frame material with a heat sink of a two-way lead part having only a different plate thickness, the lead parts are provided in four directions around the heat sink part so as to have more sufficient heat dissipation and a sufficient number of pins. Formed strips (lead frame material with heat sink)
Began to be manufactured.

[0005] As a method of manufacturing such a deformed strip lead frame material with a heat sink, a grooved roll provided with grooves at a predetermined pitch in the rolling forming direction of the deformed strip and a flat roll provided opposite thereto are used. Rolling a metal strip, a rolling roll method for manufacturing a lead frame material with a heat sink by forming a heat sink portion thicker than the lead portion at a predetermined pitch in the rolling direction, a mold having a groove corresponding to the heat sink portion, A metal strip is fed between the flat mold facing the grooved mold and pressed by the grooved mold and the flat mold to form a heat sink corresponding to the groove.
A press working method for manufacturing a lead frame material with a heat sink piece by piece, a heat sink portion (thick plate portion) of the lead frame material with a heat sink having the two-way lead portion is cut at a predetermined pitch and a predetermined width, and the heat sink portion is intermittently cut. To form lead portions at equal intervals in the longitudinal direction to produce a lead frame material with a heat sink.

[0006]

However, in the conventional method of manufacturing a lead frame material with a heat sink of a rolling roll type, a thick plate portion (heat sink portion) is obtained by rolling a metal strip while rotating a grooved roll. Therefore, when the metal strip of the heat sink section comes off from the groove, the edge of the heat sink section is shaved and it is difficult to obtain a predetermined shape. Furthermore, if the thickness ratio (thickness width of the thick plate portion / thickness width of the thin plate portion) of the lead portion (thin plate portion) and the heat sink portion (thick plate portion) is large, the difference in the processing degree becomes large, and the lead portion of the thin plate portion becomes large. This may cause undulations or defects such as necking at the boundary between the lead portion and the heat sink portion.

In the conventional method of manufacturing a lead frame material with a heat sink of a press working type, a metal strip material is pressed by a set of a grooved die and a flat die. Elongation occurs, and in particular, there is a difference in the amount of elongation between the lead portion (thin plate portion) and the heat sink portion (thick plate portion). In the case of manufacturing a lead frame by punching out the lead portion, the lead frame cannot be manufactured uniformly and continuously due to such a shift in pitch, resulting in poor productivity.

Further, in a conventional method of manufacturing a lead frame material with a heat sink having four-way leads by cutting a lead frame material with a heat sink having two-way leads, the heat sink portion (thick plate portion) is directly cut. As a result, cutting flaws remain on the surface of the lead frame, resulting in poor product yield, and consequently from the viewpoint of quality, it is not suitable for a lead frame material.

Accordingly, an object of the present invention is to form a lead frame material with a heat sink having four-way lead portions, thereby preventing deformation of a thin plate portion (lead portion) and continuously and effectively forming a lead frame material with a heat sink. Is to provide a method for producing the same.

[0010]

According to the present invention, there is provided a method for manufacturing a lead frame material with a heat sink having a thick plate portion as a heat sink portion and a thin plate portion as a lead portion. A plurality of first dies each having a groove corresponding to the plurality of first dies are arranged such that the interval between the grooves is a predetermined interval, and a second mold is disposed opposite to the plurality of first dies. A metal strip is fed between the plurality of first and second dies and pressed by the first and second dies to form a plurality of thick plate portions corresponding to the grooves. Then, the metal strip on which the plurality of thick plate portions are formed is moved at a predetermined interval or a pitch equal to an integral multiple of the metal strip over a predetermined number of times in the processing direction, and the metal strip moved at a predetermined pitch. Is determined by a plurality of first molds and second molds for each movement. There a way to press several
Thus, the side surfaces of the grooves of the plurality of first molds are inclined, and
Number of pressure plate parts are inclined with respect to the surface of the lead part
To provide a method of manufacturing a heat sink with lead frame member, characterized in that that.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 are views showing a method of manufacturing a lead frame material with a heat sink. In FIG. 1, a plurality of grooved dies 1 each having a groove 2 corresponding to a thick plate portion 7 serving as a heat sink portion are set so that the interval between the grooves 2 is constant, and the metal strip material 3 as a lead frame material is formed. A flat mold 4 having no groove is arranged in the longitudinal direction and opposed to the three grooved molds 1. Also, the bottom surface 5 of the grooved mold 1 and the upper surface 6 of the grooveless mold 4 are installed so as to be horizontal to each other.

The groove 3 of the grooved mold 1 is the mold at the right end of FIG.
As shown on behalf of 1, the side is inclined at an angle of θ
The grooved mold 1 and the grooveless mold 4
Is fixed to the press device by an appropriate method, and repeats opening and closing movements up and down. In this case, both the grooved mold 1 and the grooveless mold 4 may open and close vertically, or only the grooved mold 1 may vertically open and close.

The three grooved mold 1 and the grooveless mold 4
The metal strip 3 is fed between the molds, and the lead frame material 3 is pressed (pressed) by the three grooved molds 1 and the grooveless mold 4.

The pressed metal strip 3 forms three thick plate portions 7 corresponding to the grooves 2 of the grooved mold 1, and forms a thin plate portion 8 between the thick plate portions 7. Thin plate part 8 in this case
Is equal to the width of the gap between the grooved mold 1 and the grooveless mold 4 which is formed when the grooved mold 1 and the grooveless mold 4 are opened and closed.

FIG. 2 shows a state where the grooved mold 1 and the grooveless mold 4 are closed in vertical opening and closing movements. As can be seen from the figure, the width of the thin plate portion 8 is equal to the width of the gap between the grooved die 1 and the grooveless die 4. In this example, the thickness of the thick plate portion 7 is t2 = 0. 50 mm, and the thickness of the thin plate portion 8 is assumed to be t1 = 0.25 mm. The projection of the thick plate portion 7 formed by the groove 2 has a side length a = 7 mm.
Are arranged so that the distance (pitch) p between centers of adjacent grooves 2 is 25 mm. After the metal strip 3 has been processed to the specified pushing amount, the grooved mold 1 and the grooveless mold 4 return to the open positions as shown in FIG.

In FIG. 1, while the grooved mold 1 and the grooveless mold 4 are in the open position (while the metal strip 3 is not restrained), the metal strip 3 is moved in the longitudinal direction by an integral multiple of the pitch p. It is sent at a pitch p ′ (p ′ = n × p: n = 1, 2, 3,...). In this case, the metal strip 3 is placed in the mold 1 at least twice or more.
And 4, the metal strip 3 is fed at a pitch p 'such that pressing is performed twice or more. In FIG. 1, the feed pitch p ′ is the same as the pitch p of the thick plate portion 7. Therefore, in FIG. 1, the metal strip 3 is subjected to three times of press working. In this way, by constraining the metal strip 3 by the molds 1 and 4 a plurality of times, the thick plate portion 7 is constrained by the groove 2 provided in the grooved mold 1 and the metal strip 3 is pressed at the time of press working. The elongation in the longitudinal direction can be suppressed.

In the above description, the number of the grooved dies 1 is three. Further, a single mold may have a plurality of grooves, and the grooves may be in one or both molds.

In the above description, the three grooved dies 1
And the minimum gap width in the closed state of the grooveless mold 4 is the same width (t1 = 0.25 mm), but at least one of the plurality of molds has the same gap width as the width of the thin plate portion 8. What should I do?

Further, it is not necessary to open and close a plurality of dies all at the same time. However, if only the thick portion where the metal strip 3 has not yet been pressed is pressed first, elongation occurs in the pressed thin plate portion, and the pitch of the thick plate portion may not match. There is a need.

FIG. 3 is an enlarged cross-sectional view of a groove provided in the mold and a thick plate portion formed by pressing the groove. As shown in FIG. 3, the side surface 2a of the groove 2 is inclined at an inclination angle θ so that the horizontal cross section of the groove 2 becomes larger as approaching the opening of the groove. Due to this inclination, an edge angle θ is generated in the thick plate portion 7, and the side surface 7b of the thick plate projection 7a is inclined. The inclination angle θ may be determined depending on the final use of the thick plate portion 7 (heat sink portion), but the protrusion 7 a of the thick plate portion 7 of the metal strip 3 is easily removed from the groove 2 during press working. It is preferable to provide at an angle (for example, about 5 degrees).

The original thickness of the metal strip 3 before press working may be equal to the thickness of the final thick plate portion 7, but may be slightly smaller than that. In this case, the elongation of the metal strip 3 in the longitudinal direction due to the press working can be absorbed by collecting the strips in the thick plate portion 7.

According to the above-described method, a lead frame material with a heat sink having a good pitch accuracy of the thick plate portion can be formed. With this press working alone, the thin plate portion 8 of the metal strip 3 elongates in the width direction, and the width differs depending on the presence or absence of the thick plate 7. 3. Make a mold to punch both sides
Alternatively, the width may be made uniform by a slitter.

FIG. 4 is a schematic perspective view of the metal strip 3 (lead frame with heat sink) finally manufactured by the above-described manufacturing method. Metal strip 3 shown in FIG.
Has been processed to align both sides and has a uniform width.

[0025]

As described above, according to the method for manufacturing a lead frame material with a heat sink of the present invention, the metal strip is pressed a plurality of times by a plurality of dies with grooves. It is possible to prevent the elongation of the strip material in the longitudinal direction and prevent the thin plate portion (lead portion) from being deformed, so that a lead frame material with a heat sink can be continuously and effectively manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a method for manufacturing a lead frame material with a heat sink according to the present invention.

FIG. 2 is a diagram showing a method for manufacturing a lead frame material with a heat sink according to the present invention.

FIG. 3 is an enlarged cross-sectional view of a groove provided in a mold and a thick plate portion press-formed by the groove.

FIG. 4 is a schematic perspective view of a lead frame material with a heat sink finally manufactured by the manufacturing method of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 grooved mold 2 groove 2 a groove side surface 3 metal strip material 4 grooveless die 5 grooved die bottom surface 6 grooveless die upper surface 7 thick plate portion 7 a thick plate portion protrusion 7 b protrusion side surface 8 thin plate Department

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Makoto Oba 3550 Kida Yomachi, Tsuchiura City, Ibaraki Prefecture Within Hitachi Cable Systems Co., Ltd. (72) Inventor Noboru Hagiwara 3550 Kiyo Yomachi, Tsuchiura City, Ibaraki Hitachi (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 23/50 B21D 22/02

Claims (1)

(57) [Claims] 1. A method of manufacturing a lead frame material with a heat sink having a thick plate portion as a heat sink portion and a thin plate portion as a lead portion, wherein a plurality of first dies each having a groove corresponding to the thick plate portion. Are arranged so that the interval between the grooves is a predetermined interval, a second mold is arranged corresponding to the plurality of first molds, and the plurality of first molds and the second molds are arranged. A metal strip is fed between the molds and pressed by the plurality of first molds and the second mold to form the plurality of thick plate portions corresponding to the grooves. Moving the metal strip with the portion formed in the direction of processing a predetermined number of times at a pitch equal to the predetermined interval or an integer multiple thereof, and moving the metal strip at the pitch at each movement The plurality of first molds and the second mold What A method of pressing a predetermined number of times, the inclination on the side surfaces of the plurality of grooves of the first mold is provided, before
The plurality of pressure plate portions have inclined surfaces with respect to the surface of the lead portion.
A method for manufacturing a lead frame material with a heat sink, which is formed .