an interface between the fixture insert and a device under test 60 which may be for example a semiconductor device or any other device as shown in fig1 the interface between the device under test 60 and the fixture insert 18 is shown as being partially filled with fluid 62 although fig1 shows the fluid 62 as occupying only a portion of the interface between the device under test 60 and the fixture insert 18 it will be readily understood that such an illustration is merely for instructional purposes and in practice the fluid from the porous portions 34 36 would wick across the entire interface between the device under test 60 and the fixture insert 18 as shown in fig1 accordingly the second capillary effect which wicks water between the device under test 60 and the fixture insert 18 aids in conducting heat from the device under test 60 into the fixture insert 18 which in turn passes heat to the block 12 that includes the heat sink 24 additionally the elimination of the thermal grease leaves the device 60 free from residue of non water soluble thermal conductor such as wakefield grease preliminary testing reveals that the use of the disclosed cooling technique can increase product test yield by as much as 10 percent and may save 30 percent on pre and post preparation costs additionally the use of the disclosed technique may enhance the die thermal transfer performance during device testing by as much as 45 percent over the use of the wakefield grease technique further the use of.