Lead frames for mounting ceramic electronic parts, particularly ceramic capacitors, where the coefficient of thermal expansion of the lead frame is less than that of the ceramic
US6081416A · kind A · utility
Inventors
Key dates
| Filing date | May 28, 1998 |
| Grant date | Jun 27, 2000 |
| Priority date | — |
| Expiry date | May 28, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K3/3426
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A ceramic electrical device or component, normally a barium titanate ceramic capacitor, having a first coefficient of thermal expansion (CTE), typically about 10 parts per million per degree centigrade (10 ppm/.degree.C.), is physically and electrically mounted through an intermediary solder layer, normally copper, to a lead frame, normally made from a selected alloy of nickel-iron, having a second CTE at least one-fifth (20%) less, and more typically about 5 ppm/.degree.C., or one-half (50%) less, than is the CTE of the ceramic capacitor. Because ceramics are stronger in compression than in tension, the ceramic capacitor held within the lead frame is less likely to undergo a stress fracture at temperatures elevated above those of assembly than would be the case should the CTE's be equal, or should the CTE of the lead frame be greater than the CTE of the ceramic capacitor. Leaded ceramic capacitors, stacked multilayer ceramic capacitors, ceramic inductors and ceramic resistors so constructed satisfy United States standards for electronic components used in broad-temperature-range demanding military and space applications.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.