Semiconductor integrated circuit packages

Abstract

A lead frame for mounting a semiconductor chip in an integrated circuit package incorporates a deformation absorbing member as an integral part of the paddle support arm so that the initial, desired physical and electrical characteristics are unaltered after a forming operation such as paddle downsetting.

Description

It can also be seen that the paddle is positioned lower than the lead frame fingers; i.e., it is depressed with respect to at least a portion of the lead frame fingers. This arrangement is desirable because it facilitates making, e.g., the electrical connections as previously discussed. The paddle support arms are bent to accommodate the vertical mismatch and each has a deformation absorbing member which localizes the deformation to the vicinity of that member.

FIG. 2 is a top view of the single site depicted in FIG. 1 of a typical lead frame. Depicted are a lead frame site comprising an external mounting frame 13, a paddle 3, a plurality of fingers 7, and a plurality of paddle support arms 9 extending from the paddle. Each paddle support arm has a deformation absorbing member 11. For reasons of clarity, not all fingers are depicted. In the embodiment depicted in FIG. 2, the deformation absorbing member 11 comprises an annular member, i.e., a member with expanded dimensions in the direction perpendicular to the major axis of the paddle support arm. The annular member is depicted as being circular although other shapes, e.g., oval, can be used.

During the forming operation, i.e., as the paddle is depressed with respect to the external mounting frame, and to at least a portion of the lead frame fingers, the deformation absorbing member constricts in the direction perpendicular to the axis of motion. However, due to the size and shape of the deformation absorbing member, the desired electrical and physical characteristics are maintained after the forming operation as the paddle support arm does not form a necked down region. Thus, it is essential that the deformation absorbing member compensate for the axial motion along the paddle support arm. Further steps required for packaging need not be desired in detail as they are well known to those skilled in the art.

FIG. 3 illustrates another embodiment of a paddle support arm 11 having a deformation absorbing member which comprises a T bar with the two ends of the T mounted to the external mounting frame and to at least a portion of the fingers. During the forming operation, the paddle support arms move radially inward causing the ends of the T to deflect about the mounting axis in the direction shown by the arrows.

Other embodiments are contemplated, and two embodiments are depicted in FIGS. 4 and 5. In FIG. 4 the deformation absorbing member comprises an S bend while in FIG. 5 it comprises a wrinkle. FIG. 6 shows the wrinkle along line A-A' in FIG. 5.

Claims

1. A semiconductor integrated circuit package comprising: a semiconductor integrated circuit chip; a lead frame, said lead frame having a paddle on which said chip is mounted and paddle support arms; and an external mounting frame having a plurality of fingers, electrical connections from said chip to said fingers, said paddle being connected to said external mounting frame by said paddle support arms CHARACTERIZED IN THAT said paddle support arms comprise a deformation absorbing member, said paddle being depressed with respect to said external mounting frame, said deformation absorbing member localizing deformation during paddle downsetting and maintaining desired physical characteristics.

2. A package as recited in claim 1 in which said deformation absorbing member comprises a T bar.

3. A package as recited in claim 1 in which said deformation absorbing member comprises an S bend member.

4. A package as recited in claim 1 in which said deformation absorbing member comprises an annular member.

5. A package as recited in claim 1 in which said deformation absorbing member comprises a wrinkle member.

6. A semiconductor integrated circuit package comprising:

a semiconductor integrated circuit chip;

a paddle on which said chip is mounted;

a plurality of paddle support arms, said paddle being connected to said paddle support arms;

a plurality of fingers;

electrical connections from said chip to said fingers;

CHARACTERIZED IN THAT said paddle support arms comprise a deformation absorbing member, said paddle being depressed with respect to at least a portion of said fingers, said deformation absorbing member localizing deformation during paddle downsetting and maintaining desired physical characteristics. 7. A semiconductor integrated circuit package as recited in claim 6 in which deformation absorbing member comprises a T bar. 8. A semiconductor integrated circuit package as recited in claim 6 in which deformation absorbing member comprises an S bend member. 9. A semiconductor integrated circuit package as recited in claim 6 in which deformation absorbing member comprises an annular member. 10. A semiconductor integrated circuit package as recited in claim 6 in which deformation absorbing member comprises a wrinkle member.