as the surfaces are cooled if the adhesive is a thermosetting adhesive the bond will be strong as soon as the thermosetting adhesive is cured however in the last example it may be sufficient to draw the vacuum then crimp the tube 11 the vacuum will hold for a period of time and that period of time may be sufficient for the adhesive to cure a thermoplastic adhesive or solder would have the advantage that the heat sink 3 could be removed with the application of heat however it would be preferred that the melting or softening temperature be above the normal operating temperature range of the assembly the assembly 21 of fig2 shows a prior art heat sink 23 attached to a module 25 with nuts and bolts 27 27 the consequence of warping is shown in exaggerated scale warping may be present in one or the other or both the heat sink 23 and the module 25 it may result from over tightening the nuts and bolts 27 27 or it may result from trapped foreign matter the resulting air gap is very detrimental to heat conductivity and in the extreme may render the heat sink ineffective the heat sink 23 and the module 25 have significant thickness to make them rigid enough to maintain flat surfaces at the interface but if warping occurs this rigidity makes it very difficult to restore good thermal contact fig3 shows a flexible heat sink 31 of this invention a plurality of heat sink fins 35 u2014 35 is bonded to.