| 摘要 |
<PICT:1095117/C6-C7/1> In a method of making a printed circuit, the circuit pattern is formed on an insulating plate 1 in an adhesive medium 2, metallic powder 4 is dusted on to the plate 1 and pressed to bond it to the adhesive pattern, redundant powder is removed, and a layer of metal 5 is deposited on the powder pattern by a chemical reduction process. The insulating plate 1 is preferably of phenol resin laminate, and the adhesive medium 2, which is preferably applied by screen printing and ultimately cured by heating, may be a mixture of epoxy resin and carbon, or of phenol resin, benzyl alcohol and carbon. The metallic powder 4, which is preferably a catalyst for the subsequent chemical reduction step, may be of Ag, Cu, Fe, Ni, Co, Au, Pt, Pd, or alloys thereof, or powders plated therewith. In an example, Cu is deposited on a pattern of Cu particles from a solution of copper nitrate, potash soda tartrate, caustic soda, and formaldehyde; in another example, Ni is deposited on Fe particles from a solution of nickel chloride, sodium hypophosphite, and sodium citrate. To facilitate the soldering of lead wires into holes A, which are drilled or preferably punched through plate 1, adhesive 2', particles 4', and metal layer 5' may be continued into the mouth of each hole A. In modifications, the rest of the wall of each hole A is sensitized, as by successive immersions into solutions of stannous chloride and palladium chloride, so as to attract a layer of metal during the chemical reduction step. If the surface of the plate 1 is smooth, redundant sensitizing material can be washed away before the adhesive pattern is applied Fig. 7 (not shown); if plate 1 retains the sensitizing material on its surfaces, a layer of insulating material may be applied thereover Fig. 8 (not shown), or a removable layer of paint may be applied to the surfaces before sensitization Figs. 9, 10 (not shown). Conductive patterns may be applied to both surfaces of plate 1. |
