| 摘要 |
PROBLEM TO BE SOLVED: To provide a printed circuit substrate and flow soldering method wherein the generation of phenomenon, such as solder separation, copper land separation or the like, is remarkably reduced upon flow soldering of a 3-pin lead surface-mounting IC to a printed circuit substrate employing lead-free soldering and high reliability in a solder bonding can be secured. SOLUTION: In the copper lands formed so as to be corresponding to the leads of the mounted 3-pin lead surface-mounting IC 5, the areas of two copper lands 4 formed so as to be corresponding to the leads of a second main surface having two pieces of leads are specified so as to be at least less than 50% respectively with respect to the area of a copper land 3 formed so as to be corresponding to the lead of a first main surface having one piece of lead for the IC 5. In another way, silk printing 8 is applied previously on the circumference of coating position upon fixing the IC 5 employing a preliminary fixing adhesive agent 2 and, thereafter, the flow soldering is effected by employing the lead-free solder. COPYRIGHT: (C)2006,JPO&NCIPI
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