Method of cutting and separating a bent board into...

Details Method of cutting and separating a bent board into... Method of cutting and separating a bent board into...

1999-10-04

2001-09-11

Rachuba, M. (Department: 3724)

Stone working

Sawing

C125S901000, C083S880000, C083S886000, C083S035000, C083S036000, C083S039000

Reexamination Certificate

active

06286499

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of cutting and separating a bent board into individual small divisions, and more particularly to an improvement in such cutting-and-separating method in reducing inaccurate separation which is caused by the bend of the board.
2. Related Arts
Referring to
FIG. 9
, a semiconductor wafer
30
is sucked and held on a chuck table
31
, and the semiconductor wafer
30
can be diced into individual chips when a rotary blade
32
traverses the chuck table
31
in the X-axis direction.
Likewise, a chip size packages board (abbreviated as CSP board)
33
(see
FIG. 10
) can be cut and separated into individual pellets, i.e. CSPs, when the rotary blade
32
traverses the board along each cutting line
34
(broken line).
Such a CSP board
33
has a plurality of semiconductor chips arranged crosswise on a board material and hermetically attached thereto by resin such as glass epoxy resin (not shown the details), thus providing an integrated form as shown in FIG.
10
. As seen from
FIGS. 11 and 12
, the board
33
has a significant bend. It was caused when the resin is exposed to a raised temperature at which the sealant is applied to a crosswise arrangement of chips, and when the sealant is set to provide a hermetically sealed object. Such a bent CSP board, when put on the chuck table
31
cannot be sucked thereon, thus preventing it from being fixedly held thereon. For this reason no smooth cutting is permitted.
Smooth and correct cutting cannot be permitted unless the board is held on the chuck board in stable condition.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a bent board dicing method which permits the smooth, correct cutting of the board irrespective of its significant bending.
To attain this object a method of cutting and separating a bent board having a plurality of chips arranged thereon into individual small divisions with the aid of a cutting machine including at least a chuck table for holding a workpiece and means for cutting the workpiece held on the chuck table, is improved according to the present invention in that prior to the cutting and separating of the board into the individual chips the board is cut and separated into two or more pieces each large enough to have a reduced bend, compared with the bend of the board.
The board may be cut and separated into large divisions before it is held on the chuck table.
The board may be tentatively held on the chuck table to be cut and separated into large divisions.
The cutting-and-separating of the board into large divisions may be effected so incompletely that the divided board may be contiguous from division to division by the remaining board thickness.
The cutting-and-separating of the board into large divisions may be effected so completely that the divided board may be composed of separate large divisions.
The board may be lined with an adhesive tape, by which the board can be fixedly held on the chuck table.
The board may be directly put on and held by the chuck table.
The board may be a CSP board which comprises a plurality of semiconductor chips separated a predetermined space, arranged crosswise on a board material and hermetically sealed by resin, thus providing an integrated form.
Thanks to the dividing of the board into large divisions each having no significant bend the subsequent, final divisions into individual small pieces can be effected with precision; each large division can be positively sucked and held on the chuck table in stable condition.


REFERENCES:
patent: 4266334 (1981-05-01), Edwards et al.
patent: 4572757 (1986-02-01), Spadafora
patent: 4617729 (1986-10-01), Celnik
patent: 4914815 (1990-04-01), Takada et al.

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