METHOD OF CONVERTING MATRIX-ARRANGED MICROCIRCUIT BALL LEADS MADE OF LEAD-FREE SOLDER INTO TIN-LEAD LEADS OF NEAR-EUTECTIC COMPOSITION AND SOLDER PASTE THEREFOR Russian patent published in 2014 - IPC H05K3/34 H01L21/60 

FIELD: radio engineering, communication.

SUBSTANCE: invention relates to radio electronics and can be used to convert matrix-arranged ball leads of microcircuits from lead-free solder into tin-lead leads of a near-eutectic composition with further surface mounting of radio components and integrated circuits on printed-circuit boards and forming reliable and high-quality soldered connections designed to operate in harsh operating conditions. A microcircuit with matrix-arranged ball leads made of lead-free solder based on tin and silver is placed on a flat substrate of non-solder wettable material, on which certain solder paste doses are first deposited through a meal stencil, said doses having high lead content, while providing overlapping and contacting of the ball leads and solder paste doses, further heating to a peak temperature not higher than 230°C and cooling while holding at temperature higher than 180°C until formation, during crystallisation, of new, larger ball leads consisting of a near-eutectic tin-lead solder, close to the composition of the eutectic three-component alloy Sn₆₂Pb₃₆Ag₂.

EFFECT: invention provides said conversion with minimal mechanical and thermal action on a microcircuit in order to preserve full operating capacity thereof after conversion.

3 cl, 9 dwg, 1 tbl