JP3588270B2 - Lead frame manufacturing method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a lead frame.
[0002]
[Prior art]
The lead frame has a large number of pins in response to the high integration, high functionality, and miniaturization of the semiconductor device, and the width and pitch of the leads have become fine. In particular, the inner leads are minute and have low mechanical strength, and therefore are likely to be deformed when any external force acts.
[0003]
The inner lead is automatically connected to the semiconductor chip mounted on the pad of the lead frame via a bonding wire by an ultrasonic welding method or the like. If the inner lead is deformed or displaced, the connection operation is performed. It becomes difficult. If the deformation or displacement is severe, the inner lead comes into contact with an adjacent one, causing a short circuit phenomenon, resulting in a defective product.
[0004]
The deformation or displacement of the leads such as the inner leads and the outer leads is caused not only by the application of an external force but also by the residual stress when punched and formed by a press.
[0005]
In order to eliminate the deformation and displacement due to the residual stress, the lead frame is subjected to strain relief annealing in a manufacturing process in a state where the lead is restrained to release the residual stress, and the deformation and displacement of the lead are performed. The effect of preventing the occurrence of the phenomenon is exhibited.
[0006]
Since deformation or displacement of the lead is also caused by an external force, a tape is attached to an easily deformable inner lead or the like to support and reinforce, so that means for preventing the deformation or displacement is employed.
[0007]
[Problems to be solved by the present invention]
The tape is adhered to the inner lead or the like by pressing the tape against the inner lead to provide a heating action and to be performed by an adhesive material of the tape. May occur.
[0008]
The punching of the lead frame by the press is performed by a punch while holding the lead material to be punched by a stripper. However, when the lead to be punched becomes narrower, the pressing force of the stripper is increased. Even if it is pressed strongly, the punched lead causes sagging on the punched upper surface, and the plate pressed down by the stripper has a small but concave surface.
[0009]
Due to the deterioration of the shape of the lead, the tape does not contact the inner lead uniformly, and a defective bonding portion occurs, and there is a problem that the support reinforcement of the inner lead is not completely completed especially when the number of pins is increased. is there.
[0010]
The present invention enables a tape to be stuck to each of the inner leads without a defective portion even when the lead frame has a large number of pins and the inner leads are fine in both width and pitch. The purpose is to obtain.
[0011]
[Means for Solving the Problems]
The gist of the present invention is to punch an inner lead and an outer lead around a semiconductor chip mounting area, perform strain relief annealing as necessary, plate at least the tip of the inner lead, and apply a tape to the middle of the inner lead. In a method of manufacturing a lead frame in which a connecting portion where a tip portion of an inner lead continues is cut off, the inner lead is cut by pressing a side portion along a punched lead with a stripper. The tape is to be affixed at the place where the tape is punched without pressing.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings.
In the drawing, reference numeral 1 denotes a semiconductor chip mounting area, and inner leads 2 are formed around the area 1 by pressing continuously to the semiconductor chip mounting area 1.
[0013]
In this embodiment, the inner lead 2 is formed by stamping one side of the inner lead 2 at a time. However, as shown in FIG. Punching is performed by the presser punch 5. In FIG. 2, the inner lead 2a punched and formed first is not pressed by a stripper in order to avoid complication of the drawing, but the inner lead 2a is not shown to be actually pressed by another stripper.
[0014]
The stripper 3 is provided with a notch 7 so as not to press the area 6 where the inner lead 2 is to be taped. When the inner lead 2 to be punched is pressed against the die 4, the tape is to be bonded. It does not touch the area 6. The portion pressed by the stripper 3 is slightly dented due to the reduction load, but the tape attachment area 6 has no change in thickness and the position of the upper surface of each inner lead 2 is the same. Also, during punching, the inner lead 2 to be punched is sagged on the punching side, but the location corresponding to the notch 7 is not so different, and the sagging does not increase.
[0015]
An outer lead 8 is formed continuously with the inner lead 2. The outer lead 8 may be punched after the inner lead 2 is punched, or the outer lead 8 may be punched first, and then the inner lead 2 may be punched. It can be arbitrarily determined depending on the shape, number of pins, and the like.
[0016]
A tie bar 9 is formed at a boundary between the inner lead 2 and the outer lead 8, and a support bar 10 for supporting the semiconductor chip mounting area 1 is formed.
[0017]
Thereafter, if necessary, strain relief annealing for releasing the residual stress due to processing is performed under desired conditions, and then the tip of the inner lead 2 and the semiconductor chip mounting portion 11 are plated with Au, Ag, Pd, Ni, or the like.
[0018]
After that, the tape 12 cut into a predetermined shape is pressed against the tape application area 6 of the inner lead 2 and, at the same time, a heating action is applied to apply the tape. At this time, since the tape attaching area 6 is not pressed by the stripper 3 when the inner lead 2 is punched, the height position of the upper surface is the same. As a result, the tapes 12 come into close contact with the respective inner leads 2 without causing a poor contact portion, and the tapes 12 are strongly adhered to all the inner leads 2.
[0019]
The lead frame to which the tape 2 is adhered is cut out by punching out a connecting portion to which the tip of the inner lead 2 is connected, forming individual inner leads 2 and forming a semiconductor chip mounting portion 11. The lead frame 13 is manufactured.
[0020]
Although the above-described embodiment has described the type of lead frame in which the inner leads and the outer leads are formed on all sides of the semiconductor chip mounting portion, the present invention is not limited to this. It can be applied to the formed lead frame. Further, the present invention can be applied to, for example, a LOC or COL type lead frame having no semiconductor chip mounting portion.
[0021]
【The invention's effect】
According to the present invention, when a side portion along the punched inner lead is pressed toward the die side by a stripper when punching the inner lead, the portion where the tape is to be bonded is punched without pressing, so that the tape bonding is performed. The place to be attached has the same height at the top surface of the lead without changing the thickness, and the pressing force when applying the tape is applied uniformly, and the tape adhesive is adhered. Sometimes there is no difference in the protruding length (amount of meniscus) between the inner leads, and they adhere firmly everywhere. Thus, a lead frame having a good shape can be obtained without any deformation or displacement of the inner leads. In addition, since there is no shape defect in the inner lead, there is an effect that wire bonding is performed smoothly.
[Brief description of the drawings]
FIG. 1 is a view showing a lead frame being manufactured in one embodiment of the present invention.
FIG. 2 is a diagram showing punching of an inner lead in one embodiment of the present invention.
FIG. 3 is a view showing a lead frame being manufactured in one embodiment of the present invention.
FIG. 4 is a view showing a lead frame manufactured in another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Semiconductor chip mounting area 2 Inner lead 3 Stripper 4 Die 5 Punch 6 Tape bonding area 7 Notch 8 Outer lead 9 Tie bar
10 Support bar
11 semiconductor chip mounting section 12 tape 13 lead frame

Claims (2)

An inner lead and an outer lead are punched around the semiconductor chip mounting area, plating is applied to at least the tip of the inner lead, and a tape is attached to an intermediate portion of the inner lead, and the tip of the inner lead is continued. In a method of manufacturing a lead frame for cutting a connection portion,
A method of manufacturing a lead frame, wherein when the inner lead is punched by pressing a side portion along a lead to be punched by a stripper toward a die side, a portion where the tape is to be stuck is punched without pressing. Punching the inner lead and the outer lead around the semiconductor chip mounting area, annealing, forming the semiconductor chip mounting part by punching and keeping the tip of the inner lead connected, plating at least the tip of the inner lead, In a method for manufacturing a lead frame, a tape is attached to an intermediate portion of an inner lead, and a connecting portion to which a tip portion of the inner lead is connected is cut off.
A method of manufacturing a lead frame, wherein when the inner lead is punched by pressing a side portion along a lead to be punched by a stripper toward a die side, a portion where the tape is to be stuck is punched without pressing.

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