Repair of solder bumps

A method for circuit fabrication, comprising:

• optically inspecting an array of solder bumps on a circuit substrate so as to identify a solder bump having a height above the substrate that is greater than a predefined maximum and a solder bump having a height less than a predefined minimum;
• wherein for the height of the identified solder bump above the substrate greater than the predefined maximum, the method further comprises:
• directing a first laser beam toward the identified solder bump so as to ablate a selected amount of a solder material from the identified solder bump;
• and
• after ablating the solder material, directing a second laser beam toward the identified solder bump with sufficient energy to cause the solder material remaining in the identified solder bump to melt and reflow;
• wherein for the height of the identified solder bump above the substrate less than the predefined minimum, the method further comprises:
• depositing one or more molten droplets of solder material on the identified solder bump, whereby the droplets adhere to and harden on the identified solder bump, wherein depositing the one or more molten droplets comprises ejecting the one or more molten droplets from a donor substrate in proximity to the identified solder bump by a process of laser-induced forward transfer (LIFT);
• and
• after depositing the solder material, directing the second laser beam toward the identified solder bump with sufficient energy to cause the deposited solder material to melt and reflow into the identified solder bump.