JPS6358949A - Manufacture of lead frame for semiconductor - Google Patents

Abstract

PURPOSE:To prevent the occurrence of cracks in a molding resin by a method wherein wavy shapes are formed along the long sides of a pellet-mounting part to be used to fix a semiconductor device on a lead frame so that the length of straight parts can be reduced to less than half of the total length of the long sides and corners at edges of the pellt-mounting part are trimmed. CONSTITUTION:With this design no slip is caused between a lead frame and a molding resin, and adhesive strength between the lead frame and the molding resin is enhanced so that stress can be dispersed. Wavy shapes 12 are formed along the long sides of a pellet-mounting part 3(tab part) to be used to fix a semiconductor device and the length of straight parts is reduced to less than half of the total length of the long sides. In addition, corners at edges 11 of the pellt-mounting part 3 are trimmed. Through this constitution, it is possible to alleviated stresses which are caused between the molding resin and the pellet- mounting part 3 and to prevent the occurrence of cracks.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] The present invention relates to a method of manufacturing a lead frame for a semiconductor in which a lead frame is used and a semiconductor element is sealed in a resin, and particularly relates to a pellet attaching part.

[Prior Art] FIG. 2 shows a plan view of a lead frame used in a typical resin-sealed semiconductor product. Such a lead frame has a pellet attaching part 3 (tab part) for fixing the semiconductor element 2, and Aul[lI! It consists of an inner lead part 5 for wiring wires such as J14, and an outer lead part 6 after being sealed with resin.

The material used for the lead frame is 4270I, Kovar, copper, or an alloy mainly composed of copper.

When a conventional semiconductor product using such a lead frame is completed, it looks like the cross-sectional view shown in FIG.

FIG. 2 shows a so-called dual ink lead frame, in which the pellet attaching portion 3 (tab portion) and the inner lead portion 5 are provided with ALI or ALI plating to improve bonding properties.

The range is shown by hatching. Further, 8 is a mold range.

[Problems with the prior art] When a semiconductor product in which semiconductor cables 2 are attached to pellets on a lead frame and molded resin 7 is sealed is subjected to a reliability test for thermal effects in a cycle of high and low temperatures, the mold fails. Due to the difference in thermal expansion coefficient between the resin 7 and the lead frame or semiconductor element 2, cracks 9 occur in the mold resin 7 from the corners of the lead frame, and when they reach the outside, they become gaps that reach the semiconductor element 2 from the outside. , which will impair reliability. For this reason, countermeasures such as a patent for chamfering the sides of the pellet attachment part 3 (tab part) (Japanese Patent Laid-Open No. 60-123047) or a patent for providing a recess on the back side of the pellet attachment part 3 (Japanese Patent Laid-Open No. 60-123046) are proposed. Measures are being considered.

These countermeasures require additional presses for punching out the lead frame in a predetermined pattern, resulting in high costs.

[Object of the Invention] The object of the present invention is to eliminate the drawbacks of the prior art described above, to prevent the occurrence of cracks 9 in the mold resin 7 after resin sealing, and to provide a method for manufacturing a semiconductor lead frame of high quality and reliability. It provides:

[Summary of the Invention] The gist of the present invention is that in a method for manufacturing a lead frame for a resin-sealed semiconductor, a waveform is provided on the long side of a pellet attaching portion 3 (tab portion) for fixing a semiconductor element 2, and a linear portion is formed at 17.
2 or less and further remove the edges of the pellet attachment part 3 (tab part), thereby relaxing the stress generated between the mold resin 7 and the pellet attachment part 3 (tab part) and preventing the occurrence of cracks 9. It is intended to prevent

The shape of the notch provided around the pellet attaching part 3 (tab part) needs to be rounded at the tip of the notch so as not to have sharp edges.

[Embodiment of the Invention] An embodiment of the present invention will be described with reference to FIGS. 1(A) and 1(B). FIG. 1(A) shows a plan view of the lead frame, and FIG. 1(B) is an explanatory view of the pellet attaching section 3.

The features of the present invention are the lead frame and the mold resin 7 (third
(see figure), and the adhesive force between the lead frame and the mold resin 7 is increased to disperse stress.

Reference numeral 11 indicates an edge portion of the pellet attachment portion 3 (tab portion) that has been cut, that is, four corners have been removed, and reference numeral 12 indicates a wave-shaped cutout.

[Other Embodiments] Almost the same effect can be obtained even if the wave-shaped notches 12 provided in the pellet attachment part 3 are not just circular shapes, but triangular or square shapes in succession. Further, it is also within the scope of the present invention that the periphery of the pellet attaching portion 3 is provided with wave-shaped notches 12 along almost the entire length.

[Effects of the invention] A waveform is provided on the side surface of the pellet attachment part in order to ensure the adhesion between the lead frame and the mold resin around the pellet attachment part and to disperse the stress generated between the lead frame and the mold resin. This suppresses the deformation of the mold resin after heat shock and prevents the occurrence of cracks, making it possible to commercialize semiconductor products with good moisture resistance.

[Brief explanation of drawings]

FIG. 1A is a plan view of a lead frame according to the present invention, and FIG. 1B is an explanatory diagram of a pellet attaching part. FIG. 2 is a plan view of a lead frame used in a typical resin-sealed semiconductor product, and FIG. 3 is a cross-sectional view of a conventional semiconductor product. 2: Semiconductor element, 3: Pellet attaching part (tab part), 4: Au1tlli! . 5: Inner lead part, 6: Outer lead part, 7: Mold resin, 8: Mold range, 9: Crack, 11: Edge cut, 12: Wave cutout. b) Gu 2 < I-1 fold-sea force special

Claims (1)

[Claims] In a method for manufacturing a so-called resin-sealed semiconductor lead frame in which a semiconductor element is sealed in a resin using a lead frame, the long side of the pellet attaching part for fixing the semiconductor element of the lead frame is provided with a corrugated shape to form a linear shape. length by 1/
A method for manufacturing a lead frame for semiconductors, characterized in that the lead frame has a diameter of 2 or less and the edges of the pellet attaching part are rounded.