Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
1998-06-11
2001-01-23
Osele, Mark A. (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
C156S583200, C029S426300, C029S426400, C029S426500, C438S464000
Reexamination Certificate
active
06176966
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of die bonding electronic components and a die bonding apparatus therefor. More particularly, the present invention is concerned with a method of die bonding electronic components, which, in demounting chips from a dicing tape in the process for producing small electronic components such as semiconductor chips, enables suctioning of the chips one at a time so that these are separated from each other without the need to conduct the conventional push-up by means of pins and is also concerned with a die bonding apparatus therefor.
BACKGROUND OF THE INVENTION
Referring to
FIGS. 9 and 10
, a semiconductor wafer
40
of, for example, silicon or gallium arsenide is produced in the form of a disk having a large diameter. This semiconductor wafer
40
is stuck through a pressure sensitive adhesive sheet
41
onto a ring frame
42
. Subsequently, the semiconductor wafer
40
is cut apart into a multiplicity of dice formed chips
44
(dicing) by the use of a dicing saw
43
. In this state, the semiconductor wafer is transferred to the subsequent steps such as cleaning, drying and die bonding steps. In this process, after the completion of the dicing step, the pressure sensitive adhesive sheet
41
is drawn outward by appropriate means so that the spacings of the mutually neighboring chips
44
are expanded.
It is desired that the conventional pressure sensitive adhesive sheet
41
have satisfactory adhesive strength to the chips
44
from the dicing step in which the wafer is cut apart into dice formed chips through the drying step. Further, referring to
FIG. 11
, it is desired that, in picking up the chips from the pressure sensitive adhesive sheet
41
, the adhesive strength be such that no residue of pressure sensitive adhesive is attached to the chips
44
.
Various pressure sensitive adhesive sheets of the above type have been proposed in, for example, Japanese Patent Laid-open Publication Nos. 60(1985)-196956 and 60(1985)-223139. Further, in recent years, pressure sensitive adhesive sheets in which a UV curable pressure sensitive adhesive is used for reducing the adhesive strength at the time of pick-up have been proposed. However, the conventional pressure sensitive adhesive sheets
41
have a drawback in that, in the use thereof, it is difficult to realize uniform spacings between the chips
44
at the stage of expanding the chip spacings, thereby causing a spacing dispersion, with the result that the processing at each step encounters disorders. Further, bringing the adhesive strength at pick-up (vertical peeling strength) to complete nil is practically unfeasible, and the reduction of the vertical peeling strength at pick-up has encountered a limit of about 100 to 300 g/10 mm
2
. Therefore, at the die bonding step at which a pick-up is carried out, the pressure sensitive adhesive sheet
41
must be forcibly pushed up from the back thereof with the use of a push-up needle
45
. Therefore, there are disorders such as damaging of the chips
44
or migration of, for example, the pressure sensitive adhesive which adheres to the push-up needle
45
to the back of the chips
44
.
Still further, the pressure sensitive adhesive sheet in which a UV curable pressure sensitive adhesive is used has not yet reached a stage such that all the chips
44
can be peeled without the need to use the push-up needle
45
. The present applicants have proposed a technique in which the area of adhesion and the adhesive strength between the chips and the sheet are reduced by the use of a shrink film which can be shrunk by heating in place of the pressure sensitive adhesive sheet in which a UV curable pressure sensitive adhesive is used.
The present invention has been made with a view toward resolving the above problems of the prior art. The present invention provides a method of die bonding electronic components, in which use is made of a shrink film capable of expanding the chip spacings by a mechanism that is radically different from that of the conventional expansion method to thereby enable effective bonding without damaging the chips. The present invention also provides a die bonding apparatus therefor.
SUMMARY OF THE INVENTION
In one aspect of the present invention, there is provided a method of die bonding electronic components, comprising the steps of:
providing a dicing tape comprising at least one layer of shrink film and a pressure sensitive adhesive layer;
mounting a wafer on the dicing tape so that the wafer is stuck thereto by the pressure sensitive adhesive layer;
dicing the wafer so that the wafer is cut apart into a multiplicity of chips;
disposing the dicing tape having the multiplicity of chips stuck thereto on a table equipped with heating means, and shrinking the shrink film forming part of the dicing tape by the heating means so that an area of adhesion and adhesive strength between the chips and the adhesive layer are decreased and so that the chips are arranged with predetermined spacings; and
suctioning the chips arranged with predetermined spacings one at a time by a suction collet disposed above the chips so that the chips are separated from each other.
This method enables arranging the multiplicity of chips with substantially uniform spacings without the need to conduct the conventional expansion step including drawing outward.
In this method, it is preferred that, in the step of shrinking the at least one layer of shrink film, only a peripheral region of the dicing tape where the multiplicity of chips are not stuck is heated as a first stage to thereby form a first shrunk part, and, thereafter,
an inner region of the dicing tape where the chips are stuck is heated as a second stage to thereby form a second shrunk part,
this second shrunk part forming stage conducted so that the multiplicity of chips, neighboring each other, are arranged with predetermined spacings,
this second shrunk part forming stage followed by the sucking of the multiplicity of chips cut apart one at a time by the suction collet disposed above the chips so that the chips are separated from each other.
By virtue of the above, the conventional expansion can be avoided and the loosing of the dicing tape can be prevented.
The heating means can be disposed on an entire lower surface of the dicing tape or partially on a lower surface of the dicing tape. In the case of the latter partial disposition, it is preferred that the heating means is capable of moving along a horizontal direction synchronously with the suction collet.
Further, the heating means can be arranged so as to be movable in a vertical direction.
Still further, it is preferred that the dicing tape having the multiplicity of chips stuck thereto is disposed through a ring frame on the table, the heating means is arranged on a lower surface of the dicing tape, the chips are heated by the heating means, and the heating means is removed from the lower surface of the dicing tape, followed by the sucking of the multiplicity of chips cut apart one at a time by the suction collet disposed above the chips so that the chips are separated from each other.
By virtue of the above, not only can the dicing tape having the chips mounted thereon easily be carried onto the table but also the chips can be placed under suction one at a time and separated from each other.
Moreover, it is preferred that the dicing tape having the multiplicity of chips stuck thereto is stuck onto a ring frame, this ring frame is provided with at least two positioning notches at a predetermined distance, and pins corresponding to the notches are protrudently provided on the table at a predetermined distance, and the notches of the ring frame are fitted to the pins so that the ring frame is positioned on the table. As a result, the chip positioning on the table is facilitated.
In another aspect of the present invention, there is provided an apparatus for die bonding electronic components characterized in that
a multiplicity of diced chips are stuck on a dicing tape which is composed of at least one layer of shrink film and
Kobayashi Kenji
Tsujimoto Masaki
Lintec Corporation
Osele Mark A.
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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