| 摘要 |
<p>1,143,815. Soldering. INTERNATIONAL BUSINESS MACHINES CORP. 3 June, 1966 [18 June, 1965], No. 24733/66. Heading B3R. [Also in Division C3] A method of attaching an electrical component to a printed circuit on a substrate member comprises forming discrete areas on the circuit which are solder wettable surrounded by non- wettable areas, mounting the component with solder interposed between its terminals and the areas and heating to melt the solder and thereby to attach the component, surface tension forces maintaining the component spaced from the substrate while the solder is molten. Typically the component may be a semi-conductor device having projecting solder contact or terminal points and solder may additionally be applied e.g. by dip coating to the solder wettable areas of the printed circuit. Rosin or other suitable flux is applied to the solder points on the printed circuit by brushing, spraying or dipping before the component is applied thereto. The printed circuit conductors may consist of a material which is not solder wettable and the required solder wettable areas formed by printing dots of wettable material thereon or by treating the conductor surface to render it wettable; alternatively the conductors may be of a solder wettable material and the required areas marked off by the application of a non-conductive, non-wettable material such as a glass frit or polymeric material; alternatively again as shown in Fig. 5, the solder wettable conductive material 24 may be applied directly to the substrate 20, and non-wettable conductors 22 printed so as partly to overlap the material 24, solder 26 being applied to the exposed parts of the material 24 which subsequently becomes united to the solder 6 projecting from the semiconductor device 4. The preferred solder composition is between 5 and 40% tin and 95 to 60% lead but other low melting point alloys which may be combinations of indium, gallium, silver, gold and antimony may be used. The conductors which are non-wettable by solder consist primarily of a noble metal but contain also a high melting point metal oxide (see Division C3) and can be rendered solder wettable by polishing or abrading the surface.</p> |
