Fluxless flip chip interconnection
US6495397B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 28, 2001 |
| Grant date | Dec 17, 2002 |
| Priority date | — |
| Expiry date | Mar 28, 2021 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/49144
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A flip chip method of joining a chip and a substrate is described. A thermo-compression bonder is utilized to align the chip and substrate and apply a contact force to hold solder bumps on the substrate against metal bumps on the chip. The chip is rapidly heated from its non-native side by a pulse heater in the head of the bonder until the re-flow flow temperature of the solder bumps is reached. Proximate with reaching the re-flow temperature at the solder bumps, the contact force is released. The solder is held above its re-flow temperature for several seconds to facilitate wetting of the substrate's metal protrusions and joining. Metal caps comprised of a noble metal such as palladium is applied to the surface of the metal bumps to prevent the metal bumps (which generally comprise a highly-conductive and highly-reactive metal such as copper) from oxidizing in the elevated temperatures just prior to and during the re-flow operation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.