Special Mask for Circuit Repair Via Laser Exchange Plating
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
The use of the positive shift in the rest potential for plating at a copper/copper 2+ interface has been described in several earlier references, e.g. [*]. The shift to a more positive potential occurs when a portion of the interface is heated, causing it to become cathodic. The cooler or unheated region gives up ions, and thereby charge conservation is maintained. Thus, plating and etching occur simultaneously but along different portions of the sample, depending on its temperature; hence, a thermally driven exchange plating occurs. One of the difficulties with using this method for plating to bring about a repair is that there can be a shortage of sacrificial ions from the circuit needed to maintain the charge neutrality. Thus, the colder portion of the circuit can become very thin or even dissolve completely.