JP3110413B2 - Lead cutting equipment for semiconductor devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lead cutting device for a semiconductor device, and more particularly to a lead cutting device for cutting a gull-wing-shaped external lead from a surface-mounted semiconductor device using a lead frame.

[0002]

2. Description of the Related Art As a semiconductor device, a surface mount type semiconductor device using a lead frame has been developed.

This type of semiconductor device has external leads 2 protruding from a package 1 for surface mounting on a circuit board or the like.
Is formed into a gull-wing shape as shown in FIG. To form the external lead 2 into a gull wing shape, the external lead 2 is cut using a lead cutting device,
Gull wing shaped external lead 2 is soldered to circuit board 3
It is designed to join.

As shown in FIGS. 3 (b) and 3 (c), the external leads 2 of the surface mount type semiconductor device are soldered to secure wettability with the solder 4 when soldering to the circuit board 3. Plating 5 is applied.

When the external leads 2 of the surface mount type semiconductor device are subjected to solder plating 5 and then cut, the external leads 2 protruding from the package 1 are cut off as shown in FIG. The external lead 2 is cut by a lead cut punch 8 while being held between a die 6 and a shudder 7.

In this cutting method, as shown in FIG. 3 (b), the portion of the solder plating 5 is removed from the lead cut surface 2a of the external lead 2, and the material of the lead frame is exposed.

[0007] Therefore, the lead cut surface 2a of the external lead 2 formed through the above-described steps is shown in FIGS. 3 (b) and 3 (c).
As shown in (1), since there is no solder plating 5, there is a problem that the wettability with the solder 4 is deteriorated when mounting on the circuit board 3.

Means for solving the above problem is disclosed in Japanese Unexamined Patent Publication No.
It is disclosed in Japanese Patent Publication No. 204091.

The means disclosed in Japanese Patent Laid-Open No. 8-204091 is such that a small amount of solder plating 5 is left (secondarily applied) on the lead cut surface 2a of the external lead 2 shown in FIG. I have.

More specifically, as shown in FIG. 5, the rake face of the lead cut punch 8 for cutting the external lead 2 is inclined, and the advancing direction increases as the inclined face 8a moves toward the distal end face of the external lead 2. A structure in which a small amount of solder plating 5 is left on the lead cutting surface 2a of the external lead 2 so as to be unevenly distributed on the front side, or an arc portion 8b is formed on the tip of the lead cut punch 8 as shown in FIG. In this structure, a small amount of solder plating 5 is left on the lead cutting surface 2a.

In other words, the means disclosed in Japanese Patent Application Laid-Open No. 8-204091 intentionally causes sagging on the tip end surface of the external lead 2 and changes the solder plating 5 on the upper or lower surface of the external lead 2 into the lead cutting surface 2a. The solder plating 5 is rubbed while stretching the solder plating 5 on a part of the lead cutting surface 2a.

[0012]

However, according to the technique disclosed in Japanese Patent Application Laid-Open No. Hei 8-204091, the shape of the lead cut punch 8 is changed so that a small amount of the solder plating 5 remains on the lead cutting surface 2a. Became
According to this technique, the solder plating 5 is secondarily rubbed against the lead cut surface 2a by wrapping the solder plating 5 around the lead cut surface 2a. Therefore, the lead cut surface 2a is mounted when the product is mounted as shown in FIG. (A phenomenon in which the solder 4 which wets the lead cut surface 2a swells) F has a problem in that the rising amount H of the F becomes large.

In particular, a QFP (Quad Flat) is formed by bending the external lead 2 into a gull wing shape.
Package), SOP (Small Outlin)
In ePackage) or the like, the solder fillet F is not sufficiently formed, and a problem occurs in connection strength with the circuit board 3.

Further, solder plating 5 on the lead cut surface 2a
Of the lead cut punch 8 is greatly influenced by a change in shape due to wear of the tip of the lead cut punch 8 and a variation in clearance between the lead cut punch 8 and the die 6 when the lead cut die is assembled. It is very difficult to control the amount of wraparound of the solder plating 5 at a constant level.

Further, in the solder wettability inspection of the external lead 2 at the time of mounting the semiconductor device by the user, the quality of the connection is determined based on the shape of the solder fillet F on the lead cut surface 2a or the height of the solder fillet F. Often do.

Therefore, a semiconductor device manufactured by the conventional method has a problem that it is easy for a user to judge it as defective.

An object of the present invention is to provide a lead cutting device for a semiconductor device, which increases a rising amount of a solder fillet on a cut surface of a lead when the product is mounted.

[0018]

In order to achieve the above object, a lead cutting device for a semiconductor device according to the present invention comprises a die and a shedder for holding a solder-plated external lead of a semiconductor device. From the shedder to the da
In the direction of b, along said die and said shedder moves the lead cutting punch, a semiconductor device lead cutting device for cutting the outer leads in lead cutting punch,
A relief portion for causing sagging of the external lead is provided at a corner of the die on the side where the external lead presses through the lead cut punch.

Further, the relief portion is formed with a radius or a chamfer.

The dimension of the R or the chamfer is at least one third of the thickness of the external lead plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing a lead cutting apparatus for a semiconductor device according to Embodiment 1 of the present invention.

The semiconductor device lead cutting apparatus according to the first embodiment of the present invention shown in FIG.
6 and shedder 7 for holding and holding external leads 2
And a lead cut punch 8 for cutting the lead.

Then, the external lead 2 on which the solder plating 5 of the semiconductor device is applied is pressed and held between the die 6 and the shedder 7, and the lead cut punch 8 is moved in a direction crossing the external lead 2 (vertical direction in FIG. 1). The external lead 2 is moved and cut by the lead cut punch 8.

Further, in the first embodiment of the present invention, the die 6
A relief portion 9 for causing sagging of the external lead 2 is provided at a corner of the external lead pressing surface 6a on the lead cut punch passing side, and the relief portion 9 is formed of R.

[0025] Here, the magnitude of the curvature radius of the relief portion 8, technically discussed. FIG. 3 shows the solder wettability inspection of the external lead 2 when the user mounts the semiconductor device.
As shown in (d) and (e), the shape of the solder fillet F on the lead cutting surface 2a or the height H1 of the solder fillet F
In many cases, the quality of the connection is determined based on the information.

When judging the quality of the connection, the height H1 of the solder fillet F of the lead cut surface 2a, which is judged to be a good connection, is 50% of the thickness of the external lead 2 on average.
% Is used as a reference, and if it exceeds 50% or more, it is determined that the connection is good.

[0027] Solder height of fillet results of experiments performed to exceed more than 50% of the external lead thickness user requests reference solder coating rate of lead cutting surface 2a of the outer leads 2 during implementation, external If the thickness of the lead 2 is at least 1/3 or more, the height H1 of the solder fillet F at the time of mounting is 5 times the lead thickness required by the user.
It was concluded that it could exceed 0% or more.

[0028] Therefore, in the first embodiment of the present invention, the curvature of R constituting the escape portion 9 radius (size) is set to the size of the external lead plate thickness of at least 1/3. And
The magnitude of the radius of curvature (dimension) of R constituting the escape portion 9 is:
Although it is determined by the solder plating area required for the lead cut surface of the external lead 2, about 1/2 of the thickness of the external lead 2 is most desirable.

On the other hand, the tooth tip 8a of the lead cut punch 8
Are formed substantially at right angles to the moving direction of the lead cut punch 8.

Next, the operation when the external lead of the semiconductor device is cut using the semiconductor device lead cutting device according to the first embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 1A, first, the external leads 2 protruding from the package 1 of the semiconductor device are held by the die 6 and the shedder 7 with a pressure.

Next, as shown in FIG. 1B, the lead cut punch 8 is moved in a direction crossing the external lead 2 (vertical direction in FIG. 1), and as shown in FIG. Is cut between the lead cut punch 8 and the die 6.

Since the die 6 for pressing the external lead 2 is provided with the R escape portion 9 at the corner on the lead cut punch passing side, the external lead 2 sandwiched between the lead cut punch 8 and the die 6 is provided. is sandwiched tooth tip 8a of the corners of the external lead pressing surface 6a and the lead cutting punch 8 of the die 6 without being immediately cut also lifted upward by the curvature radius (size) worth of relief portion 9.

The external lead 2 is cut when it is bent along the arc portion of the escape portion 9 while being sandwiched between the lead cut punch 8 and the die 6.

Therefore, the solder plating 5 of the external lead 2 pushed up in the traveling direction of the lead cut punch 8 is:
The side facing the escape portion 9 of the die 6 by the size of the escape portion 9 of R provided on the die 6, that is, the surface 2b side of the external lead 2 on the lead cut punch 8 side (lead cut surface 2a).
Will exist.

As described above, according to the first embodiment of the present invention, as shown in FIGS. 3D and 3E, the radius of curvature of the R escape portion 9 provided on the lead cut surface of the die 6 is determined . Since the external lead 2 is cut in a state where the solder plating 5 is stably present on the lead cutting surface 2a by the dimension, the solder adhesion area of the lead cutting surface 2a depends on the clearance between the lead cut punch 8 and the die 6. And can be kept above a certain level.

Since the solder wettability of the external lead 2 at the lead cutting surface 2a at the time of product mounting has a correlation with the area of the solder plating 5 seen from the lead cutting surface 2a, the lead cutting surface 2a
Is stable, the solder wettability at the lead cutting portion, that is, the area of the solder fillet F and the height H1
Can be stabilized above a certain level.

Embodiment 2 FIG. 2 is a sectional view showing a semiconductor device lead cutting apparatus according to Embodiment 1 of the present invention.

In the first embodiment of the present invention shown in FIG. 1, the relief portion 9 is formed by R, but in the second embodiment of the present invention, a corner portion of the external lead pressing surface 6 a of the die 6 on the lead cut punch passing side is used. In addition, a relief portion 9 that causes sagging of the external lead 2 is formed by chamfering.

In the second embodiment of the present invention, the size of the chamfer forming the clearance 9 is at least one of the thickness of the external lead plate.
/ 3 is set. The size of the chamfered dimension that forms the clearance 9 is determined by the solder plating area required for the lead cut surface of the external lead 2.
About 1/2 of the plate thickness of the external lead 2 is most desirable. Other configurations are the same as in the first embodiment.

As described above, according to the present invention, the solder plating can be expanded by the dimension of the clearance provided in the die and can be stably present on the cut surface of the lead. The area can be kept above a certain level regardless of the clearance between the lead cut punch and the die.

Further, since the solder attachment area of the cut section of the lead is stabilized, the solder wettability at the cut section of the lead, that is, the area of the solder fillet can be stabilized at a certain level or more.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a lead cutting device for a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a semiconductor device lead cutting device according to a second embodiment of the present invention;

FIG. 3A is a diagram showing a surface-mounted semiconductor device;
(B) is a cross-sectional view showing a cut section of an external lead according to a conventional example, (c) is a plan view of the same, (d) is a cross-sectional view showing a cut section of an external lead according to the present invention, ( e) is a plan view of the same.

FIG. 4 is a cross-sectional view showing a lead cutting device for a semiconductor device according to a conventional example.

FIG. 5 is a cross-sectional view showing a lead cutting device for a semiconductor device according to a conventional example.

FIG. 6 is a sectional view showing a lead cutting device for a semiconductor device according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Package 2 External lead 2a Lead cut surface 3 Circuit board 4 Solder 5 Solder plating 6 Die 7 Shedder 8 Lead cut punch 9 Escape part

Claims (3)

(57) [Claims] The method according to claim 1 external lead solder plated of the semiconductor device, by nipping held by the die and the shedder, the
In the direction from the shedder to the die, the shedder and the
Along the y, move the lead cutting punch, a semiconductor device lead cutting device for cutting the outer leads in lead cutting punch, the corner portion of the lead cutting punch passage side of the outer leads nip-pressing surface of the die, external A lead cutting device for a semiconductor device, wherein an escape portion for causing sagging of a lead is provided. 2. The lead cutting device for a semiconductor device according to claim 1, wherein the escape portion is formed by an R or a chamfer. 3. The lead cutting device for a semiconductor device according to claim 2, wherein the dimension of the R or the chamfer is at least one third of the thickness of the external lead plate.