| 摘要 |
PURPOSE:To permit pattern connection of a multi-layered wiring circuit board with a simple stage consisting of printing and solder melting by mixing metal grains which do not melt during melting of solder and have the m. p. higher than the melting temp. of the solder with pasty solder. CONSTITUTION:The solder paste is prepd. by mixing a granular solder alloy 22 which consists essentially of lead-in and the metal grains 21 which have high affinity to said solder alloy and have the m. p. higher than the m. p. of the solder alloy with flux components. The metal grains 2 are preferably formed as the grains of 10-100mum diameter by forming a metal layer consisting of copper, brass, nickel, iron or the alloy thereof on the surface of said grains at need. This solder paste is packed by a printing method into holes 20 for connecting pattern foil 15, 17 for wiring between circuit boards 16 18 which are pressurized and adhered under heating by an adhesive agent 19. The circuit boards are then passed through a reflow furnace. The pattern connection of the multi-layered wiring circuit boards is thereby executed with the simple stage without having unstableness in solder disconnection.
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