Packaging body forming method

Abstract

The invention discloses a packaging body forming method, and belongs to the field of semiconductor packaging. The method comprises the following steps: etching a base material to obtain a plurality ofpackaging units, wherein each packaging unit comprises a base island and pins, and the packaging units are connected through connecting ribs; electroplating the upper surface of the etched base material to obtain a first plating layer; installing a chip and carrying out plastic package, and then electroplating the lower surfaces of the base island and the pins to obtain a second plating layer; then cutting the connecting ribs to expose the side surfaces of pins at the two sides of the connecting ribs without cutting off of the connecting ribs; etching the connecting ribs which are not cut offto expose the first plating layer and enable the side surface of the exposed pin to be in a concave arc shape; and tinning the side surfaces of the exposed pins. By means of the method, the defect that in the prior art, side face tin plating of the dense-interval and high-thickness base material product cannot be achieved is overcome, side face tin plating of the dense-interval and high-thicknessbase material product can be achieved, and the requirement for side face tin plating of the dense-interval and high-thickness base material product can be met.

Description

technical field [0001] The invention belongs to the technical field of semiconductor packaging, and more specifically relates to a method for forming a packaging body. Background technique [0002] In the prior art, the four-side leadless flat package and the double-side leadless flat package are leadless packages, with a heat dissipation pad at the center and conductive pads on the package periphery of the heat dissipation pad. Usually the heat dissipation pad is mounted on the circuit board together with the conductive pad. However, in the prior art, after the plastic package is cut, the sides of the metal pins cannot be coated with electro-tinned layers, which directly causes the solder paste on the PCB to not climb up to the metal area on the side of the plastic package, resulting in virtual soldering on the side of the metal pins. Or the problem of cold soldering, so the tin climbing of the metal pins on the side of the plastic package is particularly critical. [000...

AI Technical Summary

Problems solved by technology

[0004] However, the existing method of pre-plating an anti-etching metal layer combined with fully etched side tin plating has certain requirements for the thickness of the metal substrate or the spacing of the pins, which cannot be met for fine-pitch products; first, fine-pitch and thick metal substrates For products, the distance between the pins is relatively close, and the metal substrate reaches a certain thickness. Under the limited etching speed, only through single-sided etching, the metal bracket between the pins cannot be completely etched, which limits the height of tin climbing; second, Even if the tin-plated position holder on the side of the metal substrate is fully etched by increasing the etching pressure or etching time, it will cause severe side etching and over-etching, resulting in a smaller outer lead size

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