TWI858719B - Laser processing method for printed circuit board and laser processing machine for printed circuit board - Google Patents

Abstract

Provided is a laser processing method for printed circuit boards and a laser processing machine for printed circuit boards, which can fully utilize the capacity of a laser oscillator and make the energy of the laser supplied to the processing part uniform, thereby improving the processing quality and processing efficiency. The laser processing method for printed circuit boards utilizes a laser oscillator whose output is controlled by a high-frequency pulse RF to irradiate a workpiece with a light beam for processing, wherein if the high-frequency pulse RF is not activated within a predetermined time from the start of processing to the end of processing, the high-frequency pulse RF is repeatedly activated for a predetermined time, and the output light beam is injected into a damper for absorbing the energy of the light beam.

Description

Laser processing method for printed circuit board and laser processing machine for printed circuit board

The present invention relates to a laser processing method for a printed substrate and a laser processing machine for a printed substrate. The printed substrate is a combined printed substrate, and an insulating layer formed of a resin containing glass fiber or filler is sandwiched between the copper layer constituting the surface and the copper layer of the lower layer. The laser processing method forms a blind hole (non-through hole, hereinafter referred to as a concave hole or BH) on the printed substrate to connect the copper layer on the surface and the copper layer of the lower layer, or processes the front and back sides of the two substrates to form through holes (through holes, hereinafter referred to as through holes or TH) to connect the copper layer on the front and the copper layer on the back.

First, the structure of conventional laser processing machines is explained.

Figure 5 is a structural diagram of a conventional laser processing machine.

Laser oscillator 1 outputs pulsed linearly polarized laser beam 2 (hereinafter referred to as "beam 2").

The beam diameter adjustment device 3 disposed between the laser oscillator 1 and the plate 6 is a device for adjusting the energy density of the light beam 2. The energy density of the laser 2 is adjusted by changing the outer diameter of the light beam 2. That is, the energy of the light beam 2 before and after the beam diameter adjustment device 3 does not change. Therefore, the light beam 2 emitted from the beam diameter adjustment device 3 can be regarded as the light beam 2 output from the laser oscillator 1. Therefore, the laser oscillator 1 and the beam diameter adjustment device 3 are combined and referred to as the laser output device 1A. In addition, it is also possible not to use the beam diameter adjustment device 3. The polarization conversion device 4 is disposed between the beam diameter adjustment device 3 and the plate 6. The polarization conversion device 4 converts the linearly polarized light beam 2 into the circularly polarized light beam 5. In addition, the polarization conversion device 4 has a reflected light shielding mechanism (since this mechanism is familiar to the industry, it will not be described in detail here), which shields the light beam 5 reflected from the processing part during processing, and has the function of preventing the light beam 5 reflected from the processing part from damaging the laser oscillator 1. The plate 6 arranged between the polarization conversion device 4 and the galvanometer reflector 7a is formed of a material (such as copper) that the light beam 5 cannot pass through, and has a plurality of selectable apertures 8 (a kind of window, here a circular through hole) formed at a predetermined position. The plate 6 is driven by a driving device omitted in the figure to position the axis of the selected aperture 8 to a position coaxial with the axis of the light beam 5.

As shown by the arrow in the figure, the galvanometer device 7 is composed of a pair of galvanometer mirrors 7a and 7b whose respective rotation axes are orthogonal to each other, and the reflection surface can be positioned at an arbitrary angle. The galvanometer mirrors 7a and 7b and the fθ lens 9 constitute an optical axis positioning mechanism C, and the optical axis of the light beam 5 is positioned at a desired position on the printed substrate 10. The optical axis positioning mechanism C is supported by the support frame 30 so that it can be freely positioned along the vertical direction Z relative to the processing head not shown in the figure. The processing area 11 determined by the rotation angle of the galvanometer mirrors 7a and 7b and the diameter of the fθ lens 9 is about 50mm×50mm in size. The hood 40 surrounds the bottom of the fθ lens 9 and the top of the processing area 11 to be processed, and is supported so as to be freely positioned in the vertical direction Z relative to the support frame 30 supporting the optical axis positioning mechanism C, and is internally connected to a suction device omitted in the figure. In addition, the hood 40 is positioned before processing, and its lower end is positioned at a position with a predetermined gap between it and the surface of the printed substrate 10, so that the amount of particles or splashes such as copper or insulating materials generated during processing on the surface of the fθ lens 9 or the printed substrate 10 can be reduced. The printed substrate 10 as a workpiece is fixed on the XY stage 12. The control device 20 controls the operation of the laser oscillator 1, the beam diameter adjustment device 3, the drive device of the plate 6, the galvanometer mirrors 7a, 7b, and the XY stage 12 according to the input control program.

Refer to Figures 5 and 6. Figure 6 is a diagram showing the processing area 11 and the processing sequence example in the printed circuit board 10.

Taking the printed circuit board 10 as an example, the plurality of processing areas 11 are divided into processing areas 1101-1112, which are arranged in 3 rows in the direction X and divided into 4 sections in the direction Y. When processing the concave holes, after the XY stage 12 is moved so that the fθ lens 9 faces any designated one of the processing areas 1101-1112, first, the copper layer of all the concave holes in the processing area is irradiated with a light beam once (that is, irradiated with a pulse of the light beam 5, the irradiation time, that is, the pulse width is, for example, 15 μs ) to process the concave holes (the concave holes opened on the copper layer are called windows), and then, by irradiating a single or multiple light beams (the pulse width is, for example, 15 μs ), the insulating layer below the window is processed to complete the concave holes in this processing area. In addition, processing usually starts from the processing area 1101 on the left end of the figure, and is processed in the order shown by the arrow R in the figure, and finally ends in the processing area 1112.

In addition, the laser oscillator 1 is a device that outputs laser light by oscillating the laser medium inside it when a high-frequency pulse RF is input, and the laser light output is controlled by the on/off of the input high-frequency pulse RF. That is, the laser light oscillates when the high-frequency pulse RF is turned on, and the laser light oscillates when the high-frequency pulse RF is turned off. If the oscillation frequency of the laser oscillator 1 is 10kHz, the pulse period is 100μs.

However, if the laser oscillator 1 is a carbon dioxide laser oscillator, the output becomes unstable during the period from when the energy accumulated in the laser medium reaches a certain value after the laser oscillator 1 is activated (hereinafter referred to as the "stabilization period at activation"). Furthermore, even after the laser oscillator 1 is activated, for example, if the X-Y stage 12 moves between processing areas, the light beam 5 is not irradiated during the movement period, so the interval of laser oscillation becomes longer as the movement time becomes longer, which may cause the output of the light beam 5 to become unstable. In order to stabilize the beam output in this situation, the size of the high-frequency pulse RF input to the laser oscillator 1 is set to a size that does not exceed the output of the laser 2 (this state is called the simmer state) to ensure that a stable output can be obtained at the beginning of processing. In this way, even after the laser power supply is just started or the X-Y stage 12 is just moved, a concave hole with a practical diameter can be processed immediately.

Here, the stabilization period during the above startup is about 5 seconds (5000ms). In addition, the movement time required for the X-Y stage 12 to move from one processing area to the next processing area is more than 200ms. If the interval of laser oscillation is less than 20ms, the output of the laser oscillator will not decrease.

As for the concave hole processing in the processing area 11, the pulse frequency is usually about 2~3kHz (that is, the average time of the pulse interval is 0.3~0.5ms).

The problem that the invention aims to solve:

As described above, except for the stabilization period at startup, if the movement time required for the XY stage 12 to move the processing area 11 is long, the laser oscillator 1 can be put into a pre-ignition state, so that, for example, when processing a copper layer with a thickness of 2 μm , a concave hole with a hole diameter of 50 μm can be processed at a pulse frequency of less than 3.5 kHz, and a practical concave hole processing result can be achieved.

However, if the processing is performed at a pulse frequency of 3.5kHz or more, the diameter of the processed concave hole will be more than 5% smaller than the target concave hole diameter. Therefore, simply putting the laser oscillator 1 into a pre-ignition state is not enough to fully utilize the capacity of the laser oscillator 1, and cannot improve the processing quality and processing efficiency.

The purpose of the present invention is to provide a laser processing method and a laser processing machine for printed circuit boards, which can fully utilize the capabilities of the laser oscillator and make the beam mode (energy distribution in the beam diameter direction, that is, output distribution) of the laser supplied to the processing part uniform, thereby improving the processing quality and processing efficiency.

The inventors of the present invention conducted the following experiment to study the reason why the diameter of the processed concave hole becomes smaller after the pre-combustion state ends. That is, the pulse period is set to a certain frequency (2~3kHz) commonly used, and the laser oscillator is stopped in units of 10ms, and then oscillated again. The output change at this time is measured with a power meter, and the beam pattern is measured with an infrared camera to confirm the obtained beam pattern and beam diameter changes. From the experiment, it is known that the output is roughly fixed regardless of the length of the stop time, but if it is assumed that the beam diameter after the oscillation is restarted is 1, the beam diameter will shrink to about 0.9 after about 20ms and stabilize. Since the normal processing is set to use a beam whose diameter does not change after about 20ms as mentioned above, the output of the beam after restarting the oscillation will be 1/(1/0.9×0.9) after about 20ms, which is a decrease of 81%. Therefore, the diameter of the processed concave hole is smaller than the target diameter.

Furthermore, the reason for the above-mentioned change in beam diameter is as follows. That is, when the excitation of the laser medium stops, the temperature of the laser medium between the electrodes inside the laser oscillator 1 decreases, causing the refractive index to increase. Therefore, if the laser medium is excited again, the refractive index decreases as the temperature of the laser medium increases, thereby reducing the beam diameter. Therefore, when the temperature of the laser medium stabilizes, the beam diameter will also stabilize in this reduced state.

Referring to FIG. 5 and FIG. 7 , FIG. 7 is a diagram showing the beam mode after the laser oscillation is restarted. In the figure, Dr is the beam diameter of the beam Br when the laser oscillation is just restarted, and Ds is the beam diameter of the beam Bs after 20 ms from the start of oscillation, and Dr>Ds. In addition, wr is the output intensity of the beam Br, and ws is the output intensity of the beam Bs, and ws>wr. In addition, when the beams Bs and Br pass through the aperture 8, their beam diameters are converted to the diameter Da of the aperture 8, and are collected by the f θ lens 9 and collected into a diameter dw on the surface K (i.e., the imaging position) of the workpiece (printed substrate 10). In addition, Dw in the figure represents the diameter of the beam 5 incident on the f θ lens 9 (i.e., emitted from the f θ lens 9). WS in the figure is the output intensity of the light beam Bs, and the diameter of the processing threshold g of the light beam Bs on the surface K (the diameter of the concave hole completed) is DS. WR in the figure is the output intensity of the light beam Br, and the diameter of the processing threshold g of the light beam Br on the surface K (the diameter of the concave hole completed) is DR. As shown in the figure, DS>DR, and the concave hole diameter will stabilize at DS after 20ms after the laser oscillation is restarted. In addition, as mentioned above, the ratio of the output intensity WS to the output intensity WR is (Ds/Dr)2. From the above results, it can be seen that by maintaining the temperature of the laser medium during the processing within a predetermined range, the processed concave hole completion diameter DS can be made uniform, and in order to maintain the temperature of the laser medium during the processing within a predetermined range, stable laser oscillation must be maintained.

Based on the above knowledge, the invention of claim 1 is: a laser processing method for printed circuit boards, which uses a laser oscillator controlled by a high-frequency pulse RF to irradiate a workpiece with a light beam for processing, and its characteristics are: from the beginning to the end of processing, if the high-frequency pulse RF is not activated within a predetermined time, the high-frequency pulse RF is repeatedly activated for a predetermined time, and the output light beam is injected into a damper for absorbing the energy of the light beam.

In addition, the invention of claim 2 is: a laser processing machine for printed substrates, equipped with a laser oscillator and an optical axis positioning device.

The laser oscillator output is controlled by a high frequency pulse RF.

The optical axis positioning device is composed of a galvanometer device and an fθ lens. The galvanometer device is composed of a pair of galvanometer reflectors and can position the optical axis of a light beam output from the laser oscillator to a desired position on a workpiece.

The characteristic of the invention is that a damper is arranged between the fθ lens and the workpiece, and the damper is used for absorbing the energy of the output light beam.

The invention of claim 3 is that the damper has a window connected to the outer edge of a processing area of the workpiece, and the window does not hinder the path of the light beam entering the processing area.

The effect of this invention is that it can fully utilize the capabilities of the laser oscillator and improve processing quality and efficiency.

1: Laser oscillator

11: Processing area

1101~1112: Processing area

12: X-Y stage

1A: Laser output device

2: Beam

3: Beam diameter adjustment device

4: Polarization conversion device

5: Beam

6: Board

7: Galvanometer device

7a,7b: galvanometer reflector

8: Aperture

9: f θ lens

10: Printed circuit board

20: Control device

30: Support frame

40: Mask

40U: Upper board

40HU: concave hole

40D: Lower plate

40HD: concave hole

40S: Side

40HS: concave hole

50: Damping

50U: Upper surface

50W: Window

Br,Bs: beam

C: Optical axis positioning mechanism

C1,C2,C3,C4: Corners

Dr, Ds, dwn, dwnm: beam diameter

Da, dw, Dw, DS, DR: beam diameter

g: Processing threshold

H: Height

K: Surface

L: Length

Lxl,Lxr,Lyu,Lyd: Waiting line

Lt: distance

LA: Width

Ow: point

Pi(Qx,Py): irradiation position point

Q(Qx,Qy): The position of the first processed concave hole

R: Arrow

W: Width

wr,ws,WS,WR: output intensity

X: Direction

Y: Direction

Z: Up and down direction

2 θ w: rotation angle

2 θ t: angle

α,β: distance

S10~S170: Steps

Other features and effects of the present invention will be clearly presented in the implementation method with reference to the drawings, wherein: FIG. 1 is a cross-sectional schematic diagram of the processing part of the laser processing machine of the present invention; FIG. 2 is a plane schematic diagram of a damper of the present invention; FIG. 3 is a flow chart showing the control steps of the present invention; FIG. 4 is a schematic diagram of an irradiation position point of the present invention when irradiating a stabilization pulse; FIG. 5 is a structural diagram of a known laser processing machine; FIG. 6 is a schematic diagram illustrating the sequence of processing multiple processing areas of a printed circuit board; and FIG. 7 is a schematic diagram illustrating the beam mode after the laser oscillation is restarted.

Before the present invention is described in detail, it should be noted that similar components are represented by the same numbers in the following description.

Type of implementation of the invention:

FIG1 is a schematic cross-sectional view showing the processing section of the laser processing machine for printed circuit boards of the present invention, wherein, among the plurality of galvanometer reflectors as a galvanometer device 7, only one galvanometer reflector 7a for positioning a light beam 5 in a direction X is drawn. In addition, since the structure other than FIG1 is the same as the structure shown in FIG5, the same symbols are given to the same items as those in FIG5 or items with the same functions, and repeated descriptions are omitted (the relevant descriptions are recorded in paragraphs [0002] to [0012] of this manual).

The laser processing machine includes a square box-shaped mask 40, a square concave hole 40HU is formed on an upper plate 40U of the mask 40, and a square concave hole 40HD is formed on a lower plate 40D of the mask 40. Here, the sizes of the concave holes 40HU and the concave holes 40HD do not interfere with the light beam 5 passing through the concave holes 40HU and the concave holes 40HD. A concave hole 40HS provided on a side surface 40S of the mask 40 is connected to an attraction device omitted in the diagram. A damper 50 made of copper is fixed to the lower plate 40D and connected to a cooling device omitted in the diagram. The thickness of the damper 50 is 2 mm, and the damper 50 is set so that during processing, its upper surface 50U is located at a height H from the surface K of a workpiece (a printed substrate 10).

Referring to FIG. 1 and FIG. 2 , the rotation angle of the galvanometer reflector 7a during processing is 2θ w, and the single-side rotation angle relative to the vertical line is θ w. The light beam 5 is directed toward the galvanometer reflector 7a, and the distance between the two ends of the light beam 5 rotating at the galvanometer reflector 7a corresponding to the direction X is the length L of a processing area 11 in the direction X. Moreover, when the light beam 5 is incident on the damping 50 in order to stabilize the output, the rotation angle of the galvanometer reflector 7a is 2θ t, and the single-side rotation angle relative to the vertical line is θ t. At the left end of the rotation of the galvanometer reflector 7a (corresponding to the left side of FIG. 2 ), the light beam 5 is incident on a waiting line Lx1 extending along a direction Y, and at the right end of the rotation of the galvanometer reflector 7a (corresponding to the right side of FIG. 2 ), the light beam 5 is incident on a waiting line Lxr extending along the direction Y. The distance between the waiting line Lxl and the waiting line Lxr is Lt. The light beam 5 shown as a dotted line in FIG. 1 is the light beam when it is incident on the boundary line of the processing area 11, and the light beam 5 shown as a dotted line in FIG. 1 is the light beam when it is incident on the waiting line Lxl or the waiting line Lxr. In FIG. 1 , Dw represents the diameter of the light beam 5 incident on the fθ lens 9 (i.e., emitted from the fθ lens 9) (hereinafter referred to as the beam diameter), and dwn is the diameter of the light beam 5 at a height H above the surface K (i.e., the diameter of the light beam 5 incident on the damper 50). Here, since the distance between the fθ lens 9 and the surface K of the workpiece (the printed substrate 10) during processing can be substantially regarded as the focal distance f, dwn=Dw×H/f. That is, for example, when the focal distance f of the fθ lens 9 is 90 mm, the height H during processing is 20 mm, and the beam diameter Dw is 30 mm, the beam diameter dwn is approximately 7 mm.

FIG. 2 is a schematic plan view of the damper 50 of the present invention. The damper 50 is square, and a window 50W is formed in the center thereof. The width of the window 50W in the direction X and the direction Y is W, and the width W is α more than the length L of the processing area 11 plus the length of a beam diameter dwnm on one side (α>0). Here, the beam diameter dwnm is the diameter of the light beam 5 passing through the aperture 8 of the maximum diameter on the damper 50. The distance between the waiting line Lxl and the waiting line Lxr and the window 50W is (dwnm/2+β), where β>0, and the width LA of the outer side of the damper 50 is longer than (Lt+dwnm). Referring to FIG. 1 , FIG. 2 and FIG. 5 , although not shown in the figure, the galvanometer reflector 7b for positioning the light beam 5 in the direction Y is the same as the galvanometer reflector 7a shown in FIG. 1 , and the rotation angle during processing is 2θ w. When the light beam 5 is incident on the damping 50 in order to stabilize the output, the unilateral rotation angle of the galvanometer reflector 7b relative to the vertical line is θ t. At the left end of the rotation of the galvanometer reflector 7b (corresponding to the upper side of FIG. 2 ), the light beam 5 is incident on a waiting line Lyu extending along the direction X (shown by a dotted chain line), and at the right end of the rotation of the galvanometer reflector 7b (corresponding to the lower side of FIG. 2 ), the light beam 5 is incident on a waiting line Lyd extending along the direction X (shown by a dotted chain line). The distance between the waiting line Lyu and the waiting line Lyd is Lt. The four corners of the window 50W are connected by an arc with a radius of (dwnm/2+α). Therefore, the light beam 5 irradiated to the damping 50 will not be emitted outside the range of the damping 50. In addition, as described above, the lengths of the waiting lines Lxl, Lxr, Lyu and Lyd are all L.

The laser processing method of the printed circuit board of the present invention utilizes a laser oscillator 1 whose output is controlled by a high-frequency pulse RF to irradiate the workpiece with the light beam 5 for processing. The characteristic is that if the high-frequency pulse RF is not activated within a predetermined time from the start to the end of processing, the high-frequency pulse RF is repeatedly activated for a predetermined time, and the output light beam 5 is injected into the damping 50 for absorbing the energy of the light beam 5.

The predetermined time refers to "the time during which the output power of the laser oscillator 1 does not decrease". As stated in paragraph [0011] of this manual, if the interval of laser oscillation is less than 20ms, the output of the laser oscillator will not decrease. Therefore, it can be set to within 20ms.

The "repeated activation of the high-frequency pulse RF at a predetermined time" means "repeated generation of a pulsed laser of a certain power". Specifically, for example, the laser used for copper layer processing in the initial processing area 11 is repeatedly generated every less than 20 ms. At this time, the repetition time is 5 seconds if it is the "laser output stabilization period at startup" (see Figure 3), and it is the time from the start of movement of the XY stage 12 to the completion of positioning if it is the "laser output stabilization period when the XY stage moves" (see Figure 3). Here, the predetermined time refers to the pulse width, for example, 15 μs .

The "injecting the outputted light beam 5 into the damper 50 for absorbing the energy of the light beam 5" means "injecting the stabilization pulse into the damper 50". Corresponding to "S30~S70 and S90~S130 in Figure 3", "irradiating the stabilization pulse" means injecting all the stabilization pulses into the damper 50.

FIG3 is a flow chart showing the control steps of the laser processing method of the printed circuit board of the present invention. Referring to FIG1, FIG3, FIG4 and FIG5, when the processing starts, the laser oscillator 1 and the control program are started (step S10), and the processing step number i is set to i=1 (step S20). Here, the processing step number i is the sequence number of the processing sequence of each processing area 11. Next, the axis of the light beam 5 is positioned at a point Pi (Px, Py) on the waiting line (e.g., the waiting line Lyu) of the damping 50 by using the galvanometer reflector 7a and the galvanometer reflector 7b (step S30) (here, the "indication Pi coordinate" indicates the position of the point P1 (Px, Py) of the waiting position of the processing area 11 of the processing step number 1), and after the positioning is completed (step S40) (here, it is confirmed that the light beam 5 is positioned at a point Pi (Px, Py) on the waiting line (e.g., the waiting line Lyu) of the damping 50), The irradiation position of the beam 5 is determined to be P1 (Px, Py). If the positioning is not completed, it is unknown where the beam 5 will be irradiated. If the irradiation position of the beam 5 is on the printed substrate 10, the printed substrate 10 will be damaged. If it is not on the printed substrate 10, the laser processing machine will be damaged). The stabilization pulse of the predetermined output and frequency is irradiated (step S50) (at this time, the stabilization pulse is all injected into the damping 50). In this way, the irradiation time is accumulated every time the stabilization pulse is irradiated. When the accumulated time reaches 5 seconds (step S60), the irradiation of the stabilization pulse is terminated (step S70). Among them, the above steps S30~S70 are the laser output stabilization period at startup.

Next, the XY stage 12 is moved to position the processing area 11 of the processing step number i at the processing position (step S80), and the galvanometer mirror 7a and the galvanometer mirror 7b are used to position the axis of the light beam 5 at the point Pi (Px, Py) on the waiting line (step S90) (the "indicating Pi coordinates" here indicate the position of the point Pi (Px, Py) of the waiting position of the processing area 11 of the processing step number i. Usually, the processing start point varies with the processing area 11, and the waiting position on a printed substrate 10 is almost never the same). After the positioning is completed (step S100) (here, it is to confirm whether the irradiation position of the light beam 5 is positioned at the waiting position Pi (Px, Py) of the processing area 11 of the processing step number i. If the positioning is not completed, it is unknown where the light beam 5 will be irradiated, and thus the product will be damaged in the end), a stabilized pulse of a predetermined output and frequency is irradiated (step S110). Moreover, each time the stabilization pulse is irradiated, it is confirmed whether the processing area 11 of the processing step number i is positioned at the specified position (that is, the position opposite to the f θ lens 9) (step S120) (here, it is confirmed whether the XY stage 12 is positioned at the processing area 11 of the processing step number i), and if the processing area 11 of the processing step number i is positioned at the specified position (that is, the position opposite to the f θ lens 9), the stabilization pulse is terminated (step S130). Hereinafter, the above steps S90 to S130 are referred to as the laser output stabilization period when the XY stage 12 moves. In this way, after the processing area 11 of the processing step number i is positioned at the designated position, the concave hole processing is performed in the processing area 11 of the processing step number i as in the past (step S140). In addition, the first step in step S140 is to use the galvanometer reflector 7a and the galvanometer reflector 7b to position the axis of the light beam 5 at the position of the concave hole to be initially processed in the processing area 11 of the processing step number i. After the processing of the concave hole in the processing area 11 of the processing number i is completed (step S150), the processing number i is set to i=i+1 (step S160), and the processing number i is compared with the maximum value of the processing number i, that is, the processing number j (step S170). If i≦j, the processing of step S80 is performed, and the processing is terminated in other cases. Here, the stabilization pulse can adopt the processing conditions when the copper layer or the insulation layer of the processing area 11 is processed, for example. In addition, the cycle of the stabilization pulse can be set to less than 20ms (frequency above 50Hz), for example. In addition, the determination method here is to adopt feedback control (steps S40, S60, S100, S120, S150), and feedforward control can also be adopted to determine the completion signal and the end signal.

FIG4 is a diagram illustrating the irradiation position of the stabilization pulse in the above flowchart, that is, point Pi (Px, Py) (i.e., Pi (Qx, Py) shown in FIG4), and point Ow is the center of the processing area 11. Here, the corners of the processing area 11 are defined as C1, C2, C3, and C4, and point Q in the figure is the position of the first concave hole to be processed in the processing area 11 of the processing step number i (i=1, that is, the processing step number is 1) (i.e., the processing start point). At this time, point Q is located in the triangle C1, Ow, and C4 (including the sides of the triangle, the same below), so the X coordinate of point P1 on the waiting line Lyu is set to be the same as the X coordinate Qx of point Q. In this way, the distance between the connection point P1 and the point Q becomes the minimum. Therefore, compared with the case where the irradiation position of the stabilized pulse is set at a point other than the point P1, the above setting can shorten the time required for the light beam 5 to be positioned from the point P1 to the point Q. Similarly, when the point Q is located in the triangle C1, C2, Ow, the Y coordinate of the point Pi on the waiting line Lxl is set to be the same as the Y coordinate Qy of the point Q; when the point Q is located in the triangle C2, C3, Ow, the X coordinate of the point Pi on the waiting line Lyd is set to be the same as the X coordinate Qx of the point Q; when the point Q is located in the triangle Ow, C3, C4, the Y coordinate of the point Pi on the waiting line Lxr is set to be the same as the Y coordinate Qy of the point Qi. If point Q is located on a diagonal line, for example, on the C1-Ow line, since the distance from this processing start point to the waiting line Lxl is the same as the distance to the waiting line Lyu, it is possible to specify either the waiting line Lxl or the waiting line Lyu.

Referring to FIG. 3 and FIG. 4, although the processing start time of step S140 will be longer, the irradiation position point Pi (Px, Py) of the stabilized pulse can of course be set to any point on the waiting line Lyu, the waiting line Lyd, the waiting line Lxl and the waiting line Lxr. At this time, the irradiation position point Pi of the stabilized pulse is preferably set near the position where the damper 50 is connected to the cooling device (omitted in the figure). At this time, the damper 50 can be circular or square, and the diameter can be larger than the beam diameter dwnm of the light beam 5 passing through the aperture 8 of the maximum diameter. In addition, the output per unit area of the stabilized pulse incident on the damper 50 is approximately 0.02% of the output when a 100 μm recess is formed in the copper layer of the printed circuit board 10.

Since the structure of the laser processing machine for printed substrates of the present invention is roughly the same as that of the laser processing machine for printed substrates in the past, it can be easily converted into the same structure as that of the present application. In addition, for example, in the case of a laser processing machine with a processing area 11 of 50×50mm, the damper 50 of the present invention is set, which will substantially reduce the processing area 11 of the laser processing machine to 30x30mm. In this way, if the printed substrate 10 of the same size is processed, the number of movements of the X-Y stage 12 will increase. However, if the processing area 11 is 30×30mm, the laser processing method for printed substrates of the present application can be easily adopted by setting the damper 50 in the present application.

In addition, the damping device 50 of the present invention is not limited to carbon dioxide laser processing machines, but can also be applied to other laser processing machines.

However, the above is only an example of the implementation of the present invention, and it cannot be used to limit the scope of the implementation of the present invention. All simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the patent specification are still within the scope of the patent of the present invention.

5: Beam

7: Galvanometer device

7a: Galvanometer reflector

9: fθ lens

10: Printed circuit board

40: Mask

40U: Upper board

40HU: concave hole

40D: Lower plate

40HD: concave hole

40S: Side

40HS: concave hole

50: Damping

50U: Upper surface

dwn: beam diameter

Dw: Diameter of the beam

H: Height

K: Surface

L: Length

Lt: distance

W: Width

X: Direction

2θ w: rotation angle

2θ t: angle

Claims (3)

A laser processing method for printed circuit boards uses a laser oscillator controlled by a high-frequency pulse RF to irradiate a workpiece with a light beam for processing. The method is characterized in that: from the beginning to the end of processing, when the high-frequency pulse RF is not activated within a predetermined time, the high-frequency pulse RF is activated for a predetermined time and continues for a period of repeated time, and the output light beam is injected into a damper for absorbing the energy of the light beam; a window is provided on the damper, and processing is performed within the window. When processing is not in progress, the light beam is positioned through a galvanometer device and irradiated at a waiting line position on the damper close to the processing position, so it is absorbed by the damper and discarded. A laser processing machine for printed substrates comprises: a laser oscillator, the output of which is controlled by a high-frequency pulse RF; and an optical axis positioning device, which is composed of a galvanometer device and an fθ lens. The galvanometer device is composed of a pair of galvanometer reflectors and can position the optical axis of a light beam output from the laser oscillator to a desired position on a workpiece. The characteristic of the machine is that a damper is arranged between the fθ lens and the workpiece, and the damper is used to absorb the energy of the output light beam. A window is arranged on the damper, and processing is performed in the window. When processing is not performed, the light beam is positioned through the galvanometer device and irradiated on a waiting line position on the damper close to the processing position, so that it is absorbed by the damper and discarded. A laser processing machine for printed circuit boards as described in claim 2, wherein the window is connected to the outer edge of a processing area of the workpiece, and the window does not hinder the path of the light beam entering the processing area.

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