Circuit board having a defined volume of solder or conductive adhesive deposited at interconnection sites for electrical circuits
US5545465A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 24, 1995 |
| Grant date | Aug 13, 1996 |
| Priority date | — |
| Expiry date | May 24, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/24917
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method of applying bonding agents, such as solder pastes and conductive adhesives, to pad sites in the manufacture of electronic circuits uses a paste injection head. A permanent mask with cavity openings is applied around conductive pads on a carrier. The conductive pads correspond to chip attachment sites. The injection head is brought into contact with a surface of the mask, and pressure is applied to a bonding agent in the injection head. The injection head is then moved over the surface of the mask, filling cavity openings with the bonding agent. The injection head is then removed from the surface of the mask. If a solder paste is used, infrared radiation is applied to filled cavity openings to evaporate a paste flux and reflow solder to form solder balls within the cavity openings projecting above the mask. If a conductive adhesive is used, a stencil is applied to the surface of the mask prior to contacting the mask with said injection head. When the cavity openings are filled, stencil is removed from the mask and the conductive adhesive filling the cavity openings is dried.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.