| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive solder ball as a substitute for mounting an area array package onto a printed wiring board. SOLUTION: In a sheet-like solder, having protrusions 12 provided on the upper and lower sides of its portion corresponding to an electrode of an area array, the thickness (t) of the sheet-like solder is not more than 1/2 of the height (h) of the entire protrusions 12 and not less than 1μm. Also, in a solder sheet having protrusions 12 and apertures provided alternately in a two-dimensional view, the protrusions 12 are provided on the upper and lower sides of the sheet- like solder in a portion corresponding to the electrode of an area array, and the thickness (t') of the sheet-like solder connecting the protrusion 12 with the protrusion 12 is not more than 0.6 times the height (h') of the entire protrusions and moreover not less than 10μm. Furthermore, a resin film having a softening point which is lower than the melting point of the solder is used in place of the sheet-like solder. |
