| 摘要 |
<p>1476599 Solder coated metal microspheres SENJU METAL INDUSTRY CO Ltd 29 Dec 1975 [24 Jan 1975] 53034/75 Heading C7F [Also in Divisions B3F and B3R] A microsphere of solder comprises a metallic core sheathed in a solder coating more than 20 microns thick which may be formed by melting at least one solder grain. The metallic core may be Cu, Cu alloys, Ag or Ag alloys, e.g. 0À35 mm. diameter and the solder may be Sn, Pb, Sn-Pb, Sn-Pb-Ag, Sn-Pb-Cd, Pb-Ag, Pb-Sn-In, Pb-In, Sn-In or Pb-Ag-In. The microspheres are preferably made with an assembly comprising a base sheet 2 of Al, Mg, stainless steel or ceramics containing a number of hollows which are 1À5 mm. diameter and 0À8 mm. deep. An optional intermediate stainless steel sheet 4, 0À2 mm. thick with holes 0À55 mm. diameter aligned with the hollows and a second stainless steel sheet 6 with 0À35 mm. diameter holes 5 may be placed on the sheet 2 with the holes 5 aligned with the holes in the sheet 4 and the hollows in the sheet 2. The sheet 6 is then displaced in one direction and metal grains, e.g. 0À25 mm. Ag grains are placed in the holes 5 and the sheet is then replaced in its original position so that the grains fall into the hollows. The process is then repeated with a 0À3 mm. diameter solder grain. The sheets 4 and 6 are then removed, flux is added to the charge in the hollows and the sheet 2 is heated to melt the solder. The metal core may be electrolessly coated with Ni prior to coating with solder.</p> |
