| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize linear formation and a small diameter for via conductors. SOLUTION: A copper foil is bonded to one side of a thermosetting insulating resin sheet 27 by hot pressing, and the copper foil is photo-etched to linearly form a pattern of a plurality of via conductors 28. After this, multiple insulating resin sheets 27 are stacked and integrated by vacuum thermocompression. After the laminate of the insulating resin sheets 27 is cut to board sizes, the top and bottom cut surfaces or both sides of a board are polished, thereby forming a laminated board 26. The bonded surface between the individual insulating resin sheets 27 in this laminated board 26 is perpendicular to the board surface. After a core sheet 22 is bonded to the bottom of the laminated board 26, solder resist patterns 29 and 30 are respectively formed on the top of the laminated board 26 and the bottom of the core sheet 22. Then, a solder ball is bonded to the bottom of the core sheet 22, thereby forming a BGA(Ball Grid Array) board 21.</p> |
