| 摘要 |
1299559 Soldering NATIONAL CASH REGISTER CO 19 April 1971 [7 May 1970] 27236/71 Heading B3R [Also in Divisions B2 C7] A soldering powder comprises a freeflowing mass of particles of solder alloy, each particle being individually covered by a continuous coating of flux material formed by liquid-liquid phase separation encapsulation. The solder alloy particles are from 10 to 500 microns in size and specific solder compositions referred to include: 38% Pb, 62% Sn; 97À5% Pb, 1À5% Ag, 1% Sn; 66% Pb, 32% Sn, 2% Sb, 0À1% As. The flux may constitute 5 to 50% by weight of the powder and may be a rosin selected from gum rosin, wood rosin tall oil rosin, or a resin acid of the abietic or pimatic types. For effecting a soldering operation the soldering powder may be made to adhere to one or both of the surfaces to be joined by contacting the surface with the powder either the surface or powder being heated to above the melting point of the flux, e.g., in a fluidized bed of the powder or by spraying. Alternatively an interleaf component may be coated in this way and then inserted between the surfaces to be joined for the soldering operation. The powder may be made to adhere to the surfaces to be joined by first applying to the surfaces an adhesive flux. Reference is made to using the powder for soldering pegs into blind holes of a metallic board, to applying the solder powder to a selected prefluxed pattern on a substrate and to interconnecting parallel perforated metallic circuit boards at selected points. An example of a coating process (see Division B2) is given in Example 1. |
