| 摘要 |
<p>1,211,638. Splitting. TEXAS INSTRUMENTS Inc. 14 May, 1968 [16 May, 1967], No. 22812/68. Heading B5E. [Also in Divisions B2 and H1] A semi-conductor wafer which has been scribed to define a plurality of segments, each of which may contain one or more semi-conductor devices or circuits, is encapsulated between two sheets of thermoplastics material and broken into individual segments which are then separated by stretching at least one of the sheets, thereby facilitating handling of individual segments. Fig. 1 shows an unbroken scribed wafer 6 of Si or Ge encapsulated between sheets 2, 4 of a thermoplastics material such as polyethylene backed by another plastics material having a higher softening point. The sheets 2, 4 are peripherally heat sealed together along a line 5, and the enclosure is evacuated through a needle 8. A second seal is made at 7 during withdrawal of the needle 8. The sheets 2, 4 may alternatively be sealed together in an evacuated chamber. An insert 3 of metal foil or high softening point plastics prevents adhesion of the wafer 6 to the upper sheet 4. The segments of the wafer 6 are broken apart by rolling, first in one direction and then at right angles thereto, while the encapsulated wafer 6 rests on a resilient support. Fig. 3 shows one apparatus for separating the segments 9 of the wafer 6. The sheets 2, 4 are clamped on to a support 14 by a ring 17 and a heated dome 15 is screwed up beneath the lower sheet 2 causing it to expand, thus spacing out the segments 9. Due to the heating the segments adhere to the sheet 2, but the insert 3, Fig. 1, prevents adhesion to the upper sheet 4. The heating also facilitates stretching. Finally the upper sheet 4 and insert 3 are removed and the segments 9 may be individually manipulated using tweezers or a suction probe. Fig. 6 shows alternative separating apparatus, in which stretching of the lower sheet 2 is effected by vacuum forming into a cavity in a mould 20 after initial removal of part 4a of the upper sheet 4 and the insert. The part of the sheet 2 carrying the wafer 6 is stretched across a disc at the base of the mould 20, which disc is provided with a pressure sensitive adhesive so that it retains the sheet 2 after vacuum forming. Thus the sheet 2 may be cut around a groove 28 in the mould 20, and the disc carrying the separated segments of the wafer 6 may be lifted out. Stretching of the sheet 2 may be facilitated during vacuum drawing by heating using radiation from above or heated gas in the mould cavity. In this method it is necessary to adhere the segments of the wafer 6 to the sheet 2 using a heated press prior to separation in the apparatus shown.</p> |
