the prior art as will be apparent from fig2 the slipping torque falls below the threshold value l periodically for intervals lasting for a time u201c a u201d during this time the tape can slacken to an extent such that the tape separates from the transfer head of the tool rendering proper operation difficult if not impossible fig3 illustrates the two measures taken in the past to avoid slackening of the tape as shown by curve u201c a u201d in fig3 the average value of the slipping torque can be set to a high value such that the torque even though it varies considerably cannot fall below the threshold value l the alternative is to keep the magnitude of the variations in the slipping torque as small as possible as exemplified by curve u201c b u201d this is accomplished by improving manufacturing tolerances and precision of assembly here again the slipping torque remains above the threshold value l as mentioned previously the slipping ratio is the ratio of the excess length of tape base material demanded by the take up reel in the absence of slippage to the length of base material fed from the supply reel whereas in prior art film transfer tools the slipping ratio in the initial stage of winding is conventionally set at about 10 see japanese utility model registration no 2532967 in accordance with this invention the slipping ratio is set at 34 or more as shown in fig4 b the outside diameter of the transfer tape on the supply reel 20 is d1 and the diameter of the belt pulley on the supply reel.