JPH11320140A - Laser cutting method and apparatus - Google Patents

Abstract

(57) [PROBLEMS] To provide a laser cutting method capable of suppressing a thermal effect generated at a cutting portion and sufficiently obtaining a minimum required energy density while suppressing an increase in size of an apparatus. It is intended to provide the device. A laser cutting method for cutting a tie bar portion (T) formed between lead frames (10) of a semiconductor device, wherein a laser beam (L) oscillated from a pulse laser oscillator (1) is applied to a length of the tie bar portion (T). 2 corresponding to
It is characterized in that the laser beam is split and the two ends of the laser beam are simultaneously applied to both ends of the tie bar to cut the tie bar.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser cutting method and a laser cutting method for cutting a tie bar portion formed between lead frames using a laser beam in a process of manufacturing a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, in the process of manufacturing a semiconductor device,
As a method for cutting a tie bar portion formed between lead frames by using a laser beam, FIGS.
The method shown in (d) is known.

That is, the method shown in FIG. 4A is a method of cutting the tie-bar portion T by scanning a laser beam L oscillated from a laser oscillator along the tie-bar portion T. In the method shown in FIG. 4B, the condensing diameter of the laser beam L is set to be slightly smaller than the width of the tie bar portion T (the dimension in the vertical direction in the figure), and the laser beam L is divided into several shots. In this method, the tie bar portion T is cut by irradiating the tie bar portion T while moving the tie bar portion T in the width direction. Further, in the method shown in FIG. 4 (c), the condensing diameter of the laser beam L is set to a diameter substantially matching the length of the tie bar portion T (the dimension in the left-right direction in the figure), and this laser beam L is By irradiating almost the entire surface of the portion T, the tie-bar portion T is cut by a single irradiation. In the method shown in FIG. 4D, the laser beam L is formed into an elliptical shape, and its long side is made larger than the width of the tie bar portion T, and its short side is made slightly shorter than the length of the tie bar portion T. In this method, the laser beam L is applied to the tie bar portion T to cut the tie bar T by a single irradiation.

[0004]

However, such a conventional cutting method has the following various problems. First, in the method shown in FIGS. 4A and 4B, the laser beam L must be irradiated for several shots in order to cut one tie bar portion T. It takes a lot of time, and the heat accumulation in the lead frame is large,
This may cause a thermal effect on the cut portion.

In the method shown in FIGS. 4 (c) and 4 (d), the diameter of the laser beam L is adjusted to the size of the tie bar portion T. It becomes difficult to obtain the minimum energy density required for laser cutting, and the tie bar portion T cannot be cut.

If an attempt is made to obtain an energy density at which laser cutting is possible, the size of the laser oscillator is increased, so that the overall size of the apparatus is increased.

[0007]

SUMMARY OF THE INVENTION According to a first aspect of the present invention, there is provided a laser cutting method comprising: a tie bar formed between lead frames of a semiconductor device; A laser cutting method for cutting a portion, wherein a laser beam oscillated from a pulse laser oscillator is divided into two portions in accordance with the length of the tie bar portion, and the divided laser beam is divided into two portions. It is characterized in that the tie bars are cut by irradiating both ends simultaneously. A laser cutting method according to claim 2 of the present invention is a laser cutting method for cutting a tie bar portion formed between lead frames of a semiconductor device, wherein a laser beam oscillated from a pulse laser oscillator is provided. To
After shaping into an oval shape extending in the width direction of the tie bar portion, the laser beam is divided into two portions corresponding to the length of the tie bar portion, and the two divided laser beams are simultaneously applied to both ends of the tie bar portion. Irradiation cuts the tie bar. A laser cutting device according to a third aspect of the present invention is a laser cutting device for cutting a tie bar portion formed between lead frames of a semiconductor device, comprising: a pulse laser oscillator for generating a laser beam; A beam splitting unit that splits the laser beam emitted from the pulse laser oscillator into two, and a processing lens that focuses the laser beam split by the beam splitting unit toward both ends in the length direction of the tie bar portion of the lead frame. It is characterized by having. A laser cutting device according to claim 4 of the present invention is a laser cutting device for cutting a tie bar portion formed between lead frames of a semiconductor device, comprising: a pulse laser oscillator for generating a laser beam; A beam shaping unit for shaping the laser beam oscillated from the pulse laser oscillator into an elliptical shape extending in the width direction of the tie bar portion, a beam splitting unit for splitting the laser beam oscillated from the pulse laser oscillator into two, And a processing lens for condensing the laser beam split by the beam splitting unit toward both ends in the length direction of the tie bar portion of the lead frame. The laser cutting device according to a fifth aspect of the present invention is characterized in that the beam splitting unit according to the third or fourth aspect is constituted by a pair of prisms having the same apex angle. . Further, the laser cutting device according to claim 6 of the present invention observes a cutting state of the tie bar portion behind the laser beam irradiated to the tie bar portion according to any one of claims 3 to 5. An observation optical system unit is provided.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. First, prior to the method of the present invention, a laser cutting device for effectively executing the method of the present invention will be described with reference to FIG.

The laser cutting apparatus according to the present embodiment includes a laser oscillator 1 as a source of a laser beam, a beam shaping unit 2 for shaping a beam shape of a laser beam L oscillated from the pulse laser oscillator 1, and A total reflection mirror 3 for guiding the laser beam L transmitted through the beam shaping unit 2 to the beam splitting unit 4, a beam splitting unit 4 for splitting the laser beam L into two, and splitting by the beam splitting unit 4. The laser beam L includes a processing lens 5 for condensing the laser beam L on a tie bar portion T (see FIG. 2) of the lead frame 10.

The beam splitting unit 4 includes two prisms 21 having the same apex angle θ as shown in FIG.
And a storage frame 22 for fixing these prisms 21
And divides the laser beam L oscillated from the pulse laser oscillator 1 into two parallel parts.

In this embodiment, an observation optical system comprising a CCD camera 6, a CRT monitor 7, a dichroic mirror 8, and an illumination lamp 9 is provided behind the irradiation direction of the laser beam L irradiated to the lead frame 10. A system unit 11 is provided, and the state of the processed portion of the tie bar portion T can be observed by the observation optical system unit 11.

In the laser cutting apparatus of the present embodiment having the above-described configuration, the laser beam L oscillated from the pulse laser oscillator 1 is shaped by the beam shaping unit 2 so that the tie bar shown in FIG. Width A of part T
To obtain a beam shape that matches the shape.

The laser beam is split into two by the beam splitting unit 4 so that the lead frame 10 tie bar portion T
The light is condensed by the processing lens 5 at two points (FIG. 2).
C portion), and the tie bar portion T of the lead frame 10 can be cut by irradiating one shot of the laser beam.

Therefore, the tie bar portion T can be
In this way, the cutting time can be shortened, the amount of heat stored in the lead frame 10 can be reduced, the thermal effect can be suppressed, and the cutting area of the tie bar portion T can be reduced. Therefore, it is possible to sufficiently secure the energy density of the laser beam L without increasing the size of the device.

In this embodiment, the cutting condition at the tie bar portion T is determined by the observation optical system unit 11.
Is captured by the CCD camera 6 of the
The status is displayed on the monitor 7 and the status can be easily confirmed.

The interval between the points condensed by the processing lens 5 can be changed by changing the vertex angle θ of the prism 21 shown in FIG. The vertex angle θ may be determined.

[0017]

As described above, according to the present invention,
The tie bar portion can be cut with a single shot, thereby shortening the cutting time, reducing the amount of heat stored in the lead frame, suppressing the thermal effect, and cutting the tie bar portion. Is small, the energy density of the laser beam can be sufficiently secured without increasing the size of the device.

By providing the observation optical system unit, the cutting condition at the tie bar can be easily confirmed.

Further, since the interval between the points condensed by the processing lens can be changed by changing the angle of the apex angle of the prism, it is possible to make the interval between the pair of laser beams conform to the length of the tie bar portion. it can.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing an embodiment of the present invention.

FIG. 2, showing an embodiment of the present invention, is a schematic plan view illustrating the irradiation state of a laser beam.

FIG. 3 shows an embodiment of the present invention and is an exploded enlarged view of a beam splitting unit.

FIG. 4 is a schematic diagram for explaining a conventional laser cutting method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 pulse laser oscillator 2 beam shaping unit 3 total reflection mirror 4 beam splitting unit 5 processing lens 6 CCD camera 7 CRT monitor 8 dichroic mirror 9 illumination lamp 10 lead frame 11 observation optical system unit 21 prism 22 storage frame A (of tie bar part) Width B Length of tie bar L Laser beam T Tie bar

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 23/50 H01L 23/50 Y

Claims (6)

[Claims] 1. A laser cutting method for cutting a tie bar portion formed between lead frames of a semiconductor device, wherein a laser beam oscillated from a pulse laser oscillator is made to correspond to the length of the tie bar portion. And cutting the tie-bar portion by simultaneously irradiating the two ends of the tie-bar portion with both ends of the tie-bar portion. 2. A laser cutting method for cutting a tie bar portion formed between lead frames of a semiconductor device, wherein a laser beam oscillated from a pulsed laser oscillator is elongated in a width direction of the tie bar portion. After shaping into a circular shape, the laser beam is divided into two portions corresponding to the length of the tie bar portion, and the two divided laser beams are simultaneously applied to both ends of the tie bar portion to cut the tie bar portion. Laser cutting method. 3. A laser cutting device for cutting a tie bar portion formed between lead frames of a semiconductor device, comprising: a pulse laser oscillator for generating a laser beam;
A beam splitting unit that splits the laser beam emitted from the pulse laser oscillator into two, and a processing lens that focuses the laser beam split by the beam splitting unit toward both ends in the length direction of the tie bar portion of the lead frame A laser cutting device comprising: 4. A laser cutting device for cutting a tie bar portion formed between lead frames of a semiconductor device, comprising: a pulse laser oscillator for generating a laser beam;
The laser beam oscillated from this pulse laser oscillator is
A beam shaping unit for shaping into an oval shape extending in the width direction of the tie bar portion, and a beam splitting unit for splitting a laser beam oscillated from the pulsed laser oscillator into two,
A laser cutting device comprising: a processing lens for condensing the laser beam split by the beam splitting unit toward both ends in the length direction of the tie bar portion of the lead frame. 5. The laser cutting device according to claim 3, wherein the beam splitting unit is constituted by a pair of prisms having the same apex angle. 6. An observation optical system unit for observing a cutting state of the tie bar portion is provided behind the laser beam applied to the tie bar portion. A laser cutting device according to any one of the above.