Method and system of controlling alloy composition during electroplating

A method of controlling alloy composition of deposited gold-tin alloy during electroplating of a large panel, the method comprising:

• masking at least one planar surface of the panel with conductive material applied in a predetermined pattern thereupon to produce a masked panel;
• placing nonconductive material in a predetermined nonconductive pattern on at least one planar surface of the masked panel;
• locating the masked panel at least partially within an electroplating solution including gold ions and tin ions, collectively comprising the gold-tin alloy, in solution at a predetermined gold:tin ratio;
• applying electrical current to the masked panel and distributing the electrical current across the planar surface via the conductive material to induce a predetermined electrical current distribution across the planar surface and thereby pull gold ions and tin ions from the electroplating solution, the pulled gold and tin ions being deposited upon a supermajority of an unmasked area of the masked panel, the supermajority of the unmasked area of the masked panel upon which the pulled gold and tin ions are deposited being entirely separated from the conductive material by at least a portion of the nonconductive material in the predetermined nonconductive pattern;
• wherein the predetermined pattern is selected to achieve deposition of the gold-tin alloy with substantially uniform alloy composition, directly corresponding to the predetermined gold:tin ratio, across the supermajority of the unmasked area of the masked panel.