Vapor phase flash fusing of printed wiring boards
US5188282A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 28, 1991 |
| Grant date | Feb 23, 1993 |
| Priority date | — |
| Expiry date | Jan 28, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K2203/088
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An improved process for the fusing a tin-lead solder mixture deposited to form a finished circuit on a printed circuit or wiring board. The method comprises the rapid or flash fusing of the circuit board having the tin-lead solder mixture deposited thereon by immersing into the vapor of an inert fluid having a boiling point just above the melting point of the solder alloy. Problems with "weak knee" conditions are avoided by adjusting the heating time-at-temperature to that which allows the desired tin-lead solder alloy to form only as a thick "mush" rather than as a molten fluid. By so doing, the solder alloy is formed without the necessary degree of fluidity that causes it to draw away from the edge or rim of plated holes in the board.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.