having a melting point of 217 u00b0 c 240 u00b0 c are also candidates high lead solders with ninety five to ninety seven percent lead and the remainder substantially of tin with a melting point of 320 u00b0 c may also be used the manner in which the electrical connections are made using in general more than one solder is discussed below fig4 illustrates an embodiment of the invention similar to fig3 except that the columns 30 are attached to the substrate 22 and an underfill layer is in place between the chip 20 and the substrate 22 although the present invention can be used to eliminate the requirement for the underfill layer in some applications it may nevertheless be desirable to include an underfill layer 28 and the principles of the invention do not exclude the used of an underfill layer fig5 illustrates an embodiment of the invention wherein columns 40 are formed of solder and have a high aspect ratio the aspect ratio may also have a much greater value such as 2 1 to 4 1 or even 10 1 referring to fig6 ims provides the option of incorporating filler particles into the molten solder to give a.