JPH1145973A - Lead frame for semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the shape of a lead frame, by forming an angle in the cross direction of a support bar in the bent section of the support bar, when a pad is displayed to a section lower than the end faces of leads by bending to the support bar supporting the pad. SOLUTION: An angle θ is set in the cross direction of a support bar 4 in a bent section 9 of the support bar 4 for a pad 3. It is desirable that the angle is kept within a range of 10-30 deg.. Consequently, since the pad 3 is displayed by forming the angles θ to the bent sections of the support bars 4, inclined planes are formed to the bent sections 9 of each support bar 4 in response to each angle θ, and these inclined planes mutually interfere to inhibit movement in each inclined-plane direction of the lead frame. Accordingly, since physical strength to the cross direction of the support bars 4 is increased, positional displacement in the cross direction of the support bar 4 for the lead frame can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lead frame for a semiconductor device, and more particularly, to a lead frame for a semiconductor device in which pads are depressed below a lead end surface.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices become more highly integrated, semiconductor elements tend to be larger and have a greater thickness. On the other hand, semiconductor devices are required to be smaller and thinner, and a lead frame as shown in FIG. 4 is generally used to satisfy such requirements.

A lead frame 1 shown in FIG. 4 is generally a TSOP (Thin Small Outline P).
Such a lead frame 1 includes a pair of frames 2 spaced apart from each other and extending along a longitudinal direction, and a rectangular semiconductor element having sides facing each other. A pad 3 for mounting, and a pad 3 extending from sides facing each other and arranged substantially parallel to the frame 2 of the pad 3 and connected to the frame 2 at substantially right angles.
, A plurality of inner leads 5 disposed around a side different from the side on which the support bar 4 of the pad 3 is provided, and a tie bar 6 connecting the inner leads 5. , A plurality of outer leads 7 connected to the inner leads 5, and a connecting piece 8 connected to the frame 2 and connecting the outer leads 7.

[0004] Such a lead frame 1 is usually formed in a state of a lead frame 1a in which a plurality of lead frames 1 for each unit are connected in a short shape as shown in FIG. At this time, as shown in FIG.
Is formed with a step by bending, whereby the pad 3 is formed so as to be located a predetermined depth below the lead end face. At this time, the bent shape of the bent portion 9 of the support bar 4 is set in parallel to the width direction of the support bar 4 to facilitate processing, as shown in FIG.

With this configuration, even when a semiconductor element having a large thickness is mounted for high integration,
The thickness of the package can be minimized, and the connection terminals of the semiconductor element and the lead frame can be connected by wires in the same plane as much as possible. Connection failure can be prevented. Further, since the resin thickness of the upper and lower portions of the semiconductor element portion can be made substantially the same during the resin sealing, the effect of preventing a package crack due to the difference in the resin thickness is also effective.

[0006] By the way, the lead frames 1a formed in such a short shape are generally conveyed and packed in a state where a predetermined number of them are stacked. However, the lead frames 1a thus depressed are stacked and stacked. In the case of carrying, for example, as described above, the bending shape of the bending portion 9 of the support bar 4 is set in parallel to the width direction of the support bar 4, so that when a plurality of lead frames 1a are stacked, Stress or lead frame 1
Due to its own weight, the lead frame 1a is displaced in the direction of the arrow shown in FIG. 3, that is, in the width direction of the support bar 4. As a result, especially when the lead frame 1a is a thin type having a small depressed amount, the inner Lead 5
There is a problem that the tip and the pad 3 come into contact with each other, and as a result, the inner lead 5 is deformed.

Even if the pads 3 and the inner leads 5 do not contact each other, if the positions of the pads 3 and the inner leads 5 are displaced in this way, a defective mounting of a semiconductor element in a later step or a bonding defect during wire bonding will occur. There was a problem that it would occur.

In order to solve such a problem, it is only necessary to prevent the lead frames 1a from being stacked or to take measures such as inserting an interlayer paper between the lead frames 1a at the time of stacking even if they are to be stacked. This leads to a decrease in efficiency and an increase in cost, which is not preferable.

[0009]

As described above, in a conventional lead frame in which the pads are depressed below the lead end surface, when a plurality of these lead frames are stacked and transported, etc. In addition, it has been difficult to prevent the occurrence of defects such as deformation of the inner lead due to contact between the inner lead and the pad due to displacement of the lead frame. The present invention has been made in view of the above circumstances, and has as its object to solve the above problems and to provide a lead frame with excellent shape and stable quality.

[0010]

In order to achieve the above object, a lead frame according to the present invention is characterized in that when a pad is depressed below a lead end face by bending a support bar for supporting the pad. The bent portion of the support bar is angled with respect to the width direction of the support bar.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a lead frame for a semiconductor device according to the present invention will be described in detail with reference to the drawings. In the present embodiment, the basic configuration of the lead frame is the same as that of the conventional example shown in FIG. 4, that is, the lead frame 1 is separated from each other and extends in a longitudinal direction with a pair of frames 2 and A pad 3 for mounting a rectangular semiconductor element having opposing sides, and a pad 3 extending from opposing sides arranged substantially parallel to the frame 2 of the pad 3 and connected substantially orthogonal to the frame 2 are supported. A plurality of support bars 4, a plurality of inner leads 5 disposed around a side different from the side on which the support bar 4 of the pad 3 is provided, a tie bar 6 connecting the inner leads 5, It comprises a plurality of outer leads 7 connected to the leads 5 and a connecting piece 8 connected to the frame 2 and connecting the outer leads 7.

In this embodiment, as in the conventional example, the support bar 4 is formed with a step by bending, so that the pad 3 is formed so as to be located a predetermined depth below the lead end surface. However, in the present embodiment, as shown in FIG. 1, an angle θ is set in the bent portion 9 of the support bar 4 with respect to the width direction of the support bar 4.

The angle θ can be set in the range of 3 ° to 45 °, but considering the good position accuracy of the lead frame and the easiness of processing, the angle θ can be set at 10 °.
It is desirable to be within the range of {-30}. Note that the angle θ may be set to the same angle for all the support bars, or a different angle may be set for each support bar. There is no restriction on the direction of the angle θ, and the angle directions of all the support bars may be set to be the same, or the angles of all the support bars may be set to different directions. Only a different direction may be set.

As described above, according to the lead frame 1a of the present invention, since the pad 3 is depressed with the angle θ at the bent portion 9 of the support bar 4, the bent portion 9 of each support bar 4 has The slopes are formed in accordance with the angle θ, and these slopes interfere with each other to suppress the movement of the lead frame 1a in the respective slope directions, whereby the physical strength of the support bar 4 in the width direction is reduced. Therefore, even when a plurality of lead frames 1a are stacked, it is possible to prevent the support bar 4 of each lead frame 1a from being displaced in the width direction.

In the present embodiment, the bent portions 9 of all the support bars 4 have an angle θ, but the present invention is not limited to this, and at least one of the support bars 4 extending from the opposing sides of the pad 3. What is necessary is just to be attached to two or more.

In this embodiment, an example in which the lead frame is formed in a short shape has been described. However, the present invention can also be applied to a case in which the lead frame is formed in a band shape or a single unit. Further, in the present embodiment, the description has been made with the lead frame used for the TSOP. However, the present invention is not limited to this. For example, the frame may be formed by adding a predetermined angle θ set in the present invention to a support bar such as DIP or SO. The present invention can be applied to a shape having a shape that can be expected to prevent the displacement, for example, a shape in which support bars extending from pads facing each other extend substantially parallel or perpendicular to the frame.

[0017]

As described above, according to the lead frame of the present invention, the bent portion of the support bar is angled so that the pad is depressed. The strength is increased, so that even when a plurality of lead frames are stacked, no misalignment of the lead frames occurs, and as a result, a lead frame of stable quality without deformation of the leads can be obtained.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a main part showing a lead frame of the present invention.

FIG. 2 is an enlarged view of a main part showing a conventional depressed shape.

FIG. 3 is an enlarged perspective view of a main part showing a conventional depressed form.

FIG. 4 is a view showing a lead frame used for TSOP.

FIG. 5 is a view showing a lead frame formed in a short shape.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1a Lead frame 2 Frame 3 Pad 4 Support bar 5 Inner lead 6 Tie bar 7 Outer lead 8 Connecting piece 9 Bending part θ Angle

Claims (1)

[Claims] In a semiconductor device lead frame in which a pad is depressed below a lead end surface by bending a support bar for supporting the pad, a bent portion of the support bar has a width of the support bar. A lead frame for a semiconductor device characterized by being angled with respect to a direction.