METHOD FOR CONTROLLING SOLDER BUMP SHAPE AND STANDOFF HEIGHT

摘要

PROBLEM TO BE SOLVED: To allow a solder bump connection to be correctly placed on a conductor and to have a proper standoff height for a device, by forming a conductor made of a material which cannot be soldered and providing a specially formed solderable region on the conductor. SOLUTION: A conductor 112 is printed on a substrate 10, and a pillar 114 is further formed on a surface 118 of the conductor 112 at a solder joint connection. As a stage for preparing for reflow, a solder bump 16 is aligned in position with an upper surface 114a of the pillar 114. The solder bump 16 is of a material which can reflow at a sufficiently low temperature, the conductor 112 is made of a material which cannot be soldered, and the pillar 114 is formed of a solderable material. As a result, the solder bump 16 forms a connection only on the pillar 114 after reflowing and is positioned. Further, a size and a shape of the pillar 114 defines a height, a shape and a distribution of a solder bump connection on the conductor 112 based on surface tension of molten solder alloy.