Power technology

AIT has developed the ability to electroplate copper up to 300 microns thick with good uniformity over a 175mm x 125mm panel. Key to this process is the outstanding adhesion between the copper and the ceramic. Values well in excess of 5N/mm have been measured during qualification. In addition the panel exhibits negligible delamination during exposure to temperatures in excess of 350 deg Centigrade.

The pattern plating process means that the feature resolution is determined by the resist characteristics and not the ability to control etching undercut. The surface of the copper is smooth and fine grained. Of particular interest is the fact that there is essentially zero voiding in the coverage of the copper. The photo right shows a power high frequency circuit with 300 micron thick copper with a gold finish.

The technology allows the economic use of a large number of plated through holes. These holes may be either open or blind. The picture left shows a substrate 16 mm x 12 mm containing 96 plated through holes. The copper is 150 microns thick and is finished with nickel and gold. The finishes available include organic antitarnish coating, electro- or electroless plated nickel and gold, electroless silver, electroless tin and photoimaged soldermask.

The copper thickness can be chosen from about 150 microns up to 300 microns depending on the end application. The feature size is from about 250 microns at the thinner end up to about 500 microns at the thicker end.