Methods and apparatus for soldering without using flux
Apparatus and method for injection molding solder and applications thereof
Surface mount solder assembly of leadless integrated circuit packages to substrates Patent #: 5346118
ApplicationNo. 741453 filed on 10/31/1996
US Classes:228/254, Adherent solid layer or coating (e.g., pretinned)228/56.3, SOLDER FORM257/E21.508, Forming solder bumps (EPO)438/613, Bump electrode438/614Plural conductive layers
ExaminersPrimary: Heinrich, Samuel M.
Attorney, Agent or Firm
International ClassH05K 003/34
AbstractA method for forming solder bumps on an electronic structure including the steps of first providing a mold made by a sheet of a mold material having a thickness greater than that of the solder bumps to be formed, the mold material has sufficient optical transparency so as to allow the inspection of a solder material subsequently filled into the mold cavities that are formed in the mold material, and a coefficient of thermal expansion that is substantially similar to the substrate which the mold will be mated to, forming a multiplicity of mold cavities in the sheet of mold material, filling the multiplicity of mold cavities with a solder material, cooling the mold to a temperature that is sufficient to solidify the solder material in the multiplicity of mold cavities, positioning the mold intimately with the electronic structure such that the cavities facing the structure, and heating the mold and the structure together to a temperature sufficiently high such that the solder material transfers onto the electronic structure.