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AssigneeHitachi Construction Machinery Co., Ltd.
InventorsNobuhiko Tada, Kojiro Ogata, Naoki Miyanagi, Yoshiaki Shimomura, Shigeyuki Sakurai, Yoshinari Nagano, Shinya Okumura, Yasushi Minomoto
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The array condition of leads (3) is detected by a photoelectric detector (41), the detection signal is subjected to signal processing to determine the timing to oscillate a pulsed laser beam, and a laser beam axis (13C) is relatively moved at a speed (v.sub.0) with a work table (21) while oscillating a pulsed laser beam (13A), thereby cutting a dam bar (5). At this time, the longitudinal size of a spot (13B) of the pulsed laser beam (13A) is adjusted to be twice or more the width of the dam bar (5) by a longitudinal beam transformer (11a), the transverse size of the spot 13B is adjusted to be not less than 1/2 but not more than 4/5 of the length of the dam bar (5) by a transverse beam transformer (11b), and a beam rotator (11c) is appropriately operated to make the longitudinal direction of the spot (13B) substantially aligned with the longitudinal direction of the lead (3) so that the spot (13B) lies across the width (W.sub.1) of the dam bar (5). As a result, the configuration after cutting the dam bar (5) becomes highly accurate and satisfactory.
A dam bar cutting apparatus for irradiating a pulsed laser beam (13A) to dam bars (5) of a lead frame (2) in a semiconductor device (1) and cutting said dam bars (5) successively, said dam bar cutting apparatus comprising a laser oscillator (10) for oscillating a pulsed laser beam (10A), a cutting optical system (14, 16) for guiding said pulsed laser beam (10A) to the cut position of a workpiece, a work nozzle (13) for emitting said pulsed laser beam (13A) guided by said cutting optical system (14, 16) therethrough and being provided at its tip end with an opening (13a) for ejecting assist gas (17A) therethrough, carriage means (21) for relatively moving an optical axis (13C) of said pulsed laser beam (13A) at a constant speed with respect to said workpiece, detection light generating means (44) for irradiating detection light (44A) to each of said dam bars (5) to be cut and thereabout on said lead frame (2), light detecting means (41) for receiving the detection light (41A) reflected by said lead frame (2) and generating a corresponding detection signal, and control means (30) for determining the timing to irradiate said pulsed laser beam (13A) based on the detection signal from said light detecting means (41) and controlling said laser oscillator (10) so that said pulsed laser beam (13A) is irradiated to a predetermined position on said dam bar (5), wherein said dam bar cutting apparatus further comprises:
A dam bar cutting method for irradiating a pulsed laser beam (13A) from a laser oscillator (10) to dam bars (5) of a lead frame (2) in a semiconductor device (1) while relatively moving an optical axis (13C) of said pulsed laser beam (13A) at a predetermined speed with respect to said semiconductor device (1), thereby cutting said dam bars (5) successively, said dam bar cutting method comprising the steps of irradiating detection light (44A) to each of said dam bars (5) to be cut and thereabout on said lead frame (2), receiving the detection light (41A) reflected by said lead frame (2) and generating a corresponding detection signal, determining the timing to irradiate said pulsed laser beam (13A) based on said detection signal, and controlling oscillation of said pulsed laser beam (13A) so that said pulsed laser beam (13A) is irradiated at said timing to a predetermined position on said dam bar (5), wherein said dam bar cutting method further comprises the steps of:
Dependencies are inferred from the claim text.