Method for selective plating of a metal substrate using laser developed masking layer and apparatus for carrying out the method

Abstract

Method for selective plating of a metal substrate, wherein the method comprises the steps of applying a thin layer of an epoxyurethane, acrylic or epoxy based plating resist on the metal substrate by electrophoretic coating; curing said plating resist on said substrate; selectively removing said plating resist from said substrate by subjecting said plating resist to a laser beam emitted by a frequency doubled Nd:YAG laser having a wavelength of 532 nm and operated at a repetition rate of about 300 Hz; and scanning said laser beam on said plating resist by means of an optical galvo system according to a pattern along which the metal substrate is to be metal plated, wherein the plating resist is selected so as to be at least substantially transparent to the said laser beam and the metal is selected to absorb at least a substantial part of the energy of said laser beam, whereby a substantial portion of the laser energy is transmitted through said plating resist and absorbed by said metal substrate resulting in said metal substrate being heated at the surface thereof to form a plasma at the interface between the coating resist and the metal substrate, the plasma causing the plating resist thereover to blow off thereby exposing the surface of the metal substrate along said pattern suitable for metal plating; and subjecting said substrate to metal plating at the exposed surface thereof.

Description

Technical field [0001] The invention relates to a method for selectively plating a metal substrate (especially an IC lead frame) using a precious metal and a device for implementing the method. In particular, the method and the corresponding equipment according to the present invention are respectively suitable for a so-called roll-to-roll and tape-to-belt plating process and equipment. Background technique [0002] In the process of selectively plating a metal substrate (such as an IC lead frame), a plating protection layer is coated on the entire surface of the metal substrate, and then the plating protection is selectively removed by laser development Floor. In this way, the plating protection layer is patterned, that is, the plating protection layer is removed from the surface of the metal substrate in the selected areas, so that the surface of the metal substrate is exposed in these areas so that a precious metal can be deposited in these areas. Plating onto the ...

AI Technical Summary

Problems solved by technology

[0006] But a shortcoming that this known method has is that, in order to be able to selectively remove the plating protection layer along the desired pattern, it is necessary to make the laser beam irradiated on the plating protection layer and the laser beam formed by the plating protection layer The relative movement between the covered metal substrates can only be achieved by mechanically moving the metal substrate while maintaining the direction of the laser beam

This makes the method unsuitable for metallizing a metal substrate in a reel-to-reel and belt-to-belt (set on conveyor belt) process, since in this case the load is placed on a conveyor The metal substrate on the strip is conveyed to a coiler from the loading point or from the feed section of an uncoiler via different processing stations (such as laser ablation station, pre-processing station, post-processing station), so The movement of the metal substrate is limited by the direction of the roll to roll and the conveyor belt, so that no pattern can be formed in any other direction

Irrespective of this limitation of the known method, the mechanical movement of the metal substrate and the repetition rate of an excimer laser up to 500 Hz would make the process slower, deviating from the current need to provide high-speed selective plating methods. departure, this is also unacceptable

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