Printed circuit board with oval solder ball lands for BGA semiconductor packages
US6268568A · kind A · utility
Assignees
Inventor
Key dates
| Filing date | May 4, 1999 |
| Grant date | Jul 31, 2001 |
| Priority date | — |
| Expiry date | May 4, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P70/50
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A PCB having oval solder ball lands, and a BGA semiconductor package produced using such a PCB, are disclosed. The PCB has a plurality of conductive traces forming circuit patterns on at least one of an upper and a lower surface of a resin substrate. A plurality of solder ball lands are formed on the lower surface of the substrate and are electrically connected to respective upper surface conductive traces. At least a portion of the solder ball lands have an oval shape and a major axis. The oval solder ball lands are oriented such that their major axes are either radially directed relative to a center of the substrate, perpendicularly directed relative to a side edge of the substrate, or both radially and perpendicularly directed relative the center and a side edge of the substrate, respectively. Solder balls welded to the oval lands have an improved strength capable of effectively resisting a shearing stress caused by a thermal expansion of the PCB during operation of a semiconductor chip, and the BGA package thus has a prolonged fatigue life. The oval solder ball lands also enlarge the width of a neck point between adjacent solder ball lands, thereby enabling a larger number of c…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.