| 摘要 |
PURPOSE:To strengthen the junction part of a package structure as well as to suppress the fusion loss of the copper layer in the solder junction interface by a method wherein fine copper-tin alloys or intermetallic compounds, which are uniformly dispersed in the solder metal layer, are contained in the package structure. CONSTITUTION:A junction interface 20 owes the roles of electrically junctioning the wiring pattern and the solder in a low-resistance state and of firmly junctioning them mechanically. A solder consisting metal layer 30 is adjusted its adhering amount in such a way that after the most important copper layer 33 thereof is properly bonded according to the composition of the solder, that is, the amounts of lead layers 31 and 35 and tin layers 32 and 34, the thickness of the copper layer 23 of the junction interface 20 and the fusion processing temperature of the solder, the copper layer 23 remains and the strength of the junction part can be held. A furnace heating is performed on the solder constituting metal layer 30 in an atmosphere of hydrogen at 250 deg.C and the solder constituting metal layer 30 is melted, and after that, the solder constituting metal layer 30 is cooled and a nearly a spherical solder ball 40 is formed. Formed copper-tin alloys or intermetallic compounds 41 are prevented from growing to bulky particles by crystal growth, and at the same time, the fine copper-tin alloys or intermetallic compounds 41 are uniformly dispersed in the ball 40, and in addition, the copper layer 23 of the junction interface 20 is suppressed from eluting in the solder. |
