according to the present invention in its most general aspect , a dual base plate heatsink is manufactured by providing two opposing base plates , each with an inward facing surface and a number of elongate landing areas separated by elongate channels . fins are placed into the channels of the opposing base plates and , while the base plates are being maintained at a constant relative distance , a swaging tool is passed in a direction parallel to the surface adjacent the fins and between the base plates . as the tool is passed it increasingly applies pressure to the landing areas of the base plate adjacent the fins to swage the base plate material against the fins . the swaging of the base plate causes pressure to be applied to the fins to force them to remain coupled to the base plates . with reference to fig1 , there is shown a dual base plate heatsink 10 made according to the preferred method of the present invention . the heatsink 10 comprises two opposing base plates 12 , each base plate having an inward - facing surface 14 . landing areas 11 of base plate 12 are separated by channels 16 and comprise an elongate jaw pair 18 , having jaws 20 . fins 22 have flared ends 24 that fit in between adjacent jaw pairs 18 of respective base plates 12 . the channels 16 in the surface 14 between the jaw pairs 18 receive the flared ends 24 of the fins 22 . as can be seen from the diagram , the fins 22 are held in place by jaws 20 which have been swaged towards the fins 22 to apply pressure to the flared ends 24 of the fins 22 . the advantage of the flared ends 24 of the fins 22 is that when the jaws 20 have been swaged , a more uniform and secure fit is achieved for increased heat transfer . with reference to fig2 , there is shown a heatsink 10 being made according to the method of the present invention , wherein a fin 22 is being lowered into one of the channels 16 between landing areas 11 of a base plate 12 . once all of the fins 22 have been placed into corresponding channels 16 between said jaw pairs 18 , the second base plate 12 is fit onto the flared ends 24 of the fins 22 . with reference to fig3 , there is shown a front view of the heatsink 10 being made according to the principles of the present invention . in this diagram , the fins 22 have been placed into corresponding channels 16 between landing areas 11 of the base plates 12 , and a swaging tool 40 ( fully illustrated in fig7 ) has been placed through the fins 22 and into the space between jaws 20 in each jaw pair 18 . this diagram shows clearly the flared ends 24 of the fins 22 in between jaw pairs 18 . furthermore , the shape of each jaw 20 is shown clearly . the jaws 20 progressively widen in cross section from the end distal to the surface 14 of the base plate 12 towards the surface 14 , and then narrow again . the base plates are maintained at a constant relative distance , as discussed in greater detail below with reference to fig7 . the widening of the jaws 20 co - operates with the wedge shape of the swaging tool 40 to progressively force the jaws 20 apart when the tines 42 of the swaging tool 40 are being passed between the respective jaws 20 in the jaw pairs 18 . furthermore , the narrowing ensures that swaging the jaws 20 causes minimal warping of the base plates 12 because of a lower bending moment . in fig4 , the tines 42 of the swaging tool 40 are caused to slide in a direction parallel to the surfaces 14 of base plates 12 and between the jaws 20 . because the tines 42 of the swaging tool 40 , shown more clearly in fig5 - 7 , are increased in height towards its second end , they push against the jaws 20 of the landing area 11 to swage them apart and against the flared ends 24 of the fins 22 . because the base plates 12 are being maintained at a constant relative distance , the jaws 20 are forced apart due to the increase in pressure from the tines 42 as the swaging tool 40 is pulled through the fins 22 . the flared ends 24 of the fins 22 are pressed into channels 16 of each base plate 12 and , because the jaws 20 of base plates 12 have been deformed , are retained therein . fig5 and 6 show a side cutaway view of a single tine 42 of the swaging tool 40 being passed between the base plates 12 . as can be seen , the widened second end of the tine 42 pushes against both jaw pairs 18 of the landing areas 11 on both base plates 12 to progressively force open the jaws 20 and push them against the flared ends 24 of the fin 22 . fig7 shows an exemplary view of the apparatus used to form the heatsink 10 according to the present invention . the uncoupled heatsink 10 is placed in a retaining structure having expansion - preventing walls 50 to maintain the base plates 12 at a constant relative distance . the swaging tool 40 is shown having multiple tines 42 that are each pulled past the fins 22 of the heatsink 10 to force open the jaws 20 in each jaw pair 18 of the landing area 11 so that the jaws 20 push against the flared ends 24 of the fins 22 to hold them in place in the channel 16 of the base plate 12 . in the embodiment of fig7 , the tines 42 are pulled by a shaft 54 passing through a hole in each tine . the shaft is , in turn , pulled by a hydraulic motor or other motive apparatus . an alternate shaft attachment hole 56 is shown in each of the tines 42 . also shown in fig7 are slide - preventing walls 52 which act to prevent the fins 22 from sliding relative to the base plates 12 when the tines 42 of said swaging tool 40 are pulled from left to right . the slide - preventing walls avoid the requirement set forth in u . s . pat . no . 5 , 406 , 698 to , after coupling of the fins 22 to the base plates 12 , remove the parts of the fins 22 that have slid relative to the base plates 12 during application of swaging pressure . a person understanding the present invention may conceive of alternatives and variations thereof . for instance , rather than employing slide - preventing walls for preventing the fins from sliding relative to the base plates , a pressure force can be applied to both base plates to increase the friction force between the fins and the base plates thereby reducing or prevent any relative movement . furthermore , whereas the flared fin ends of the preferred embodiment provide a more uniform fit for better heat transfer with the jaw pairs when swaged , uniform thickness fins can also be used . an alternative to the smooth - sided fin shape , whether flared or not , is to provide serrations on the end of the fin to improve bonding when the base plate material is deformed against the fin . all such embodiments and variations are believed to be within the purpose , sphere and scope of the invention as defined by the claims appended hereto .