JP7057646B2 - Laser processing method - Google Patents

Description

The present invention relates to a laser processing method suitable for drilling a glass substrate using a carbon dioxide laser.

In recent years, drilling holes in glass substrates using a laser has been studied, but carbon-dioxide lasers, which are expected to have high output and productivity, have problems such as easy cracking.
As a laser processing method for drilling holes without generating cracks, for example, in Patent Document 1, a carbon dioxide laser is irradiated from the protective sheet side to a drilling position of a glass substrate to which a protective sheet is attached to form a non-penetrating hole. A laser processing method is disclosed in which a protective sheet is removed from a glass substrate, an annealing treatment is performed, and the non-irradiated side of the laser of the glass substrate is polished to change the non-through hole into a through hole.

In this processing method, since the through hole is not suddenly formed at the stage of laser processing, the residual stress applied to the glass substrate can be reduced, and the occurrence of cracks during laser processing can be suppressed.
However, the diameter of the final through hole becomes smaller on the non-irradiated side of the laser, and when the hole is conductively plated, there is a drawback that the plating adhesion characteristic at this portion deteriorates.

Japanese Unexamined Patent Publication No. 2016-222485

Therefore, an object of the present invention is to provide a laser processing method that is less likely to cause cracks when drilling a glass substrate using a carbon dioxide laser and can improve the plating adhesion characteristics when conductive plating is performed on a through hole. ..

A typical laser machining method disclosed in the present application is a laser machining method in which a through hole is drilled in a glass substrate using a carbon dioxide gas laser, and the drilling position on the front and back sides of the glass substrate on which a protective sheet is attached to the front and back surfaces. A first step of irradiating the glass substrate with the laser to form a non-penetrating hole, a second step of removing the protective sheet from the glass substrate and performing an annealing treatment, and a second step of wet-etching the glass substrate. It is characterized by having 3 steps.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a laser processing method capable of improving the plating adhesion characteristics when the glass substrate is drilled using a carbon dioxide gas laser, cracks are less likely to occur, and the through holes are conductively plated.

It is a process drawing for demonstrating the laser processing method which becomes one Example of this invention, and is sectional drawing which captured the state of the glass substrate after laser irradiation. It is a process drawing for demonstrating the laser processing method which becomes one Example of this invention, and is the cross-sectional view which captured the state of the glass substrate until laser irradiation. It is a block diagram of the laser processing apparatus used in one Example of this invention.

A laser processing method according to an embodiment of the present invention will be described.
First, as a first step, for example, with respect to the work substrate 3 as shown in FIG. 2 (a) in which the protective sheet 2 is attached to the front surface and the back surface of the glass substrate 1 made of non-alkali glass, FIG. 2 (b) As shown in the above, a carbon-dioxide laser is irradiated to the drilling position on the front surface side to form the non-penetrating hole 4, and then the carbon-dioxide laser is irradiated to the drilling position on the back surface side to form the non-penetrating hole 5.
In this case, the protective sheet 2 functions to prevent the molten glass component generated by the drilling process from adhering to the surface of the glass substrate 1, and the adhesive can be easily peeled off without leaving the adhesive on the glass substrate 1 side. Is.

A configuration diagram of a laser processing device for forming the non-through holes 4 and 5 is shown in FIG. 3, but the configuration here is general. In FIG. 3, 22 is a carbon dioxide laser oscillator that oscillates the laser pulse L1, and 23 is an acousto-optic modulator that deflects the laser pulse L1 output from the carbon dioxide laser oscillator 22 in two ways, a processing direction and a non-processing direction (hereinafter referred to as AOM). (Abbreviation), 24 is a galvano scanner that sequentially irradiates the drilling position of the work substrate 3 with the laser pulse L2 deflected in the machining direction in the AOM23. The galvano scanner 24 is adapted to scan the laser pulse L2 by rotating. Reference numeral 25 is a damper that absorbs the laser pulse L3 deflected in the non-processing direction in the AOM 23.

Reference numeral 26 denotes an overall control unit that controls the operation of the entire device, and controls the deflection operation of the laser oscillation control unit 27 and the AOM 23 that output the laser oscillation command signal S instructing the oscillation of the individual laser pulses L1 in the carbon dioxide laser oscillator 22. It includes an AOM control unit 28 that outputs an AOM drive signal D, and a galvano control unit 29 that outputs a galvano operation control signal G that instructs the operation of the galvano scanner 24.
The AOM drive signal D deflects the laser pulse L1 input to the AOM 23 in the machining direction to obtain the laser pulse L2 only in the time zone when it is on, and the damper 25 as the laser pulse L3 in the non-machining direction in other time zones. Deflection in the direction of.
The galvano operation control signal G makes the galvano scanner 24 stationary in the off time zone and rotates the galvano scanner 24 in the on time zone. The laser is irradiated to one hole position while the galvano scanner 24 is stationary, and the rotation of the galvano scanner 24 causes the laser pulse L2 to be irradiated to the next hole position.

In the laser processing apparatus of FIG. 3, the non-through holes 4 and 5 are formed in the work substrate 3 by cycle processing. In the cycle processing, the hole positions are moved while irradiating one laser pulse for each hole position, and when all the hole positions are completed, the same operation is repeated as many times as necessary.

Next, as a second step, the protective sheet 2 is peeled off from the work substrate 3 in which the non-through holes 4 and 5 are formed to bring it into the state shown in FIG. 1 (a), and the glass substrate 1 in this state is subjected to annealing treatment. .. When the material of the glass substrate 1 is non-alkali glass, the temperature is 650 ° C, which is the strain point, and the time is preferably 10 minutes. However, in the case of borosilicate glass, soda lime glass, etc., it is necessary to change the temperature and time. There is. By this annealing process, the residual stress around the non-through holes 4 and 5 generated by the laser machining in the second step is relaxed.

Next, as a third step, wet etching with hydrofluoric acid is performed on the glass substrate 1. As a result, each of the non-through holes 4 and 5 is eroded, and the intermediate region between the non-through holes 4 and 5 is eroded. Further, the front surface side and the back surface side of the glass substrate 1 are also eroded.
In FIG. 1 (b), 6 indicates the intermediate region, and A indicates the thickness of the glass substrate 1 to be eroded on the front surface side and the back surface side. The degree of erosion in this case is controlled by changing the etching treatment conditions.
The state after this etching process is shown in FIG. 1 (c). The glass substrate 1 in which the intermediate region 6 between the non-through holes 4 and 5 is eroded and the through holes 7 are formed at the drilling positions is Complete.

According to the above embodiment, even when the thickness of the glass substrate 1 is large, the residual stress applied to the glass substrate 1 can be reduced by forming the through holes without suddenly forming the through holes at the stage of laser irradiation. In addition, the hole positions are moved while irradiating one laser pulse for each hole position, and when all the hole positions are completed, the same operation is repeated as many times as necessary, so that each hole position is continuous. Unlike burst processing in which a plurality of laser pulses are irradiated, the residual stress applied to the glass substrate 1 can be reduced, and the occurrence of cracks during laser processing can be suppressed.

Further, by performing the annealing treatment, the residual stress applied to the glass substrate 1 by the laser processing is relaxed, so that the occurrence of cracks can be suppressed. Furthermore, since the through hole is completed by etching, the vertical cross-sectional shape of the hole can be made close to the X shape, and when the hole is conductively plated, the plating adhesion characteristics at this part are improved from the conventional technique. Can be improved.

Moreover, since the polishing treatment is not performed, the maximum area of the glass substrate 1 is not limited, and the adverse effect of the polishing powder is not caused. Further, since the final thickness of the glass substrate 1 is determined in the process of the etching process, the accuracy of the thickness can be improved as compared with the case where it is determined by the polishing process.

In the above examples, wet etching is performed using hydrofluoric acid. However, the wet etching solution does not necessarily have to be hydrofluoric acid, and other wet etching solutions may be used.

Further, in the above embodiment, in the step of forming the non-through holes 4 and 5, the hole positions are moved while irradiating one laser pulse for each hole position, and it is necessary when all the hole positions are completed. The same operation is repeated a number of times, but it is needless to say that it is not necessary to repeat the same operation twice or more depending on the size of the non-through holes 4 and 5.

1: Glass substrate 2: Protective sheet 3: Work substrate 4, 5: Non-through hole,
6: Intermediate region, 7: Through hole, 22: Carbon dioxide laser oscillator, 23: AOM,
24: Galvano scanner, 25: Damper, 26: Overall control unit,
27: Laser oscillation control unit, 28: AOM control unit, 29: Galvano control unit,
L1 to L3: Laser pulse, S: Laser oscillation command signal, G: Galvano operation control signal, D: AOM drive signal

Claims (2)

In the laser processing method of drilling through holes in a glass substrate using a carbon dioxide gas laser, the laser is irradiated to the holes on the front and back sides of the glass substrate on which the protective sheet is attached to form non-through holes. A first step of removing the protective sheet from the glass substrate and performing an annealing treatment, and a third step of wet-etching the glass substrate to form the through hole. However, a laser processing method characterized in that the vertical cross-sectional shape of the through hole is X-shaped . In the laser processing method according to claim 1, in the first step, the hole positions are moved while irradiating one laser pulse for each hole position, and when all the hole positions are completed, the required number of times is required. A laser machining method characterized by performing cycle machining in which the same operation is repeated.

Images