Another performance test is a solder ball test. This slide shows a typical solder ball test pattern found on printed circuit boards. A 1 mm circular solderable pad is over-printed by 4 mm from center. During reflow the paste should completely coalesce and pull back onto the small center pad. Using the shorter top reflow profile, all the pastes are fairly comparable with good powder coalescence, without solder balls and satellites in the flux residue. The bottom row illustrates the same samples reflowed using the more demanding, harsher long reflow profile. Under this condition, GC 10 outperforms the comparison samples, with excellent paste coalescence, no solder balls or satellites. Again in this test, not all the comparison pastes are halogen free.