Method of forming a solder layer on pads of a circuit board and method of mounting an electronic part on a circuit board
US5118029A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Nov 26, 1990 |
| Grant date | Jun 2, 1992 |
| Priority date | — |
| Expiry date | Nov 26, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K2203/125
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A paste-like composition containing a lead salt of an organic acid and tin powder is applied on a pad array portion of a circuit board. Then, the paste-like compsition is heated so as to cause precipitation, thereby forming a solder layer formed of a Sn-Pb alloy substantially only on the pads. This precipitation is performed in a state that a liquid pool is formed on the pad array portion when the paste-like composition is liquefied by heating, and the tin powder is settled in the liquid pool. When an electronic part is mounted on the pads, first, preparatory solder layers are formed on the pads by the above-mentioned precipitation process. After a paste-like composition is applied on the preparatory solder layers, the electronic part is put on the paste-like composition. Then, the paste-like composition is heated, thereby soldering leads of the electronic part to the pads.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.