CN1659750A - Laser processing system and laser processing method - Google Patents

Abstract

A laser machining system characteried by comprising a pulse laser oscillator (2) for making the characteristics of a laser beam (6) variable by switching a discharge command pulse of a specified frequency thereby varying a discharge power being supplied between electrodes (24), and an optical system (3) for guiding the laser beam (6) delivered from the laser oscillator (2) to a work.

Description

Laser-processing system and laser processing

Invention field

The present invention relates to machined object is carried out the laser-processing system and the laser processing of perforates such as through hole, blind hole or ditch processing, profile cutting etc., particularly the raising aspect of the raising of processing quality and productivity ratio.

Background technology

Tellite is the insulating substrate that multi-disc is provided with conductor layer to be done multilayer laminated applying form.

And, be arranged at conductor layer on each insulating body and descend thereon between any conductor layer of direction and be electrically connected via the via that is referred to as through hole, blind hole.

The profile that Figure 14 uses for this existing multilayer printed board of explanation, among the figure, 1 is tellite, 11a, 11b are insulating substrate, 12a～12c is a conductor layer, 13 is electrodeposition of metals, and 14a is the conductor layer 12a of conducting insulated substrate 11a and the via between the conductor layer 12b, and 14b is the conductive layer 12a of conducting insulating substrate 11a and by the via between the conductor layer 12c of the stacked subsides of insulating substrate 11b.

Via 14a is commonly referred to as blind hole (Blind Via Hole), and via 14b is commonly referred to as through hole (Through Hole).

Have via 14a as shown in figure 14, the tellite of 14b, high performance along with electronic equipment, require tellite multiple stratification, miniaturization (densification), for satisfying this requirement, propose to utilize the method for laser beam processing via 14a, 14b shown in Figure 14 and progress has been arranged.

Figure 15 carries out schematic diagram that the laser-processing system of the perforate of through hole and blind hole use with laser beam to tellite for explanation.

Among the figure, the 1st, as the tellite of processing object thing, 2 is laser oscillator, and 3 is optical system, and 4 is machine table, and 5 is the control device of control system integral body, partly equipment room is continuous with cable for each.6,7 is laser beam, and 9 are one of laser radiation figure example, and the Pi on the laser radiation figure 9 is the peak power of laser beam, and Wi is pulse duration (beam irradiating time), and Ti is the light beam irradiates off time.

The below actual processing action of explanation.

Utilize optical system 3 to make the laser beam 6 of laser oscillator 2 outputs form light beam, transmitting and shining the processing object thing is tellite 1.

At this moment, laser beam shines a plurality of laser pulses with as shown in figure 15 9 such pulsed laser irradiation figures to each hole.The laser beam of irradiation utilizes heat melts tellite 1 and is removed, and the result forms the hole on printed substrate.

Figure 16 illustrates an example of the profile of the tellite that so is processed into.

Among Figure 16,15a is processing aperture, top, and 15b is the processing middle aperture, 15c is processing aperture, bottom, and 16 is working depth, and 17 are processing resin residue thing, 18 are the damage of inner surface Copper Foil, the identical symbol of all the other part identical marks with Figure 14, and omit its explanation.

Adding man-hour with laser beam, for guaranteeing processing quality, usually must be noted that processing aperture 15a～15c among Figure 16, working depth 16, manufacturing deficiency 7,18 etc., control beam diameter, beam energy (peak power * pulse duration) and light beam irradiates off time, beam energy particularly, because damage and distortion, plasma generation etc. to material and material formation are influential, are the important control parameters therefore.

Suppose that the laser beam energy that i sends out is Ei, the peak power of laser oscillator outlet is Pi, the transfer rate of the peak power of the laser oscillator outlet of optical system control is α i (below be called the beam Propagation rate), the light beam pulse width is Wi, (shot) number of sending out that 1 hole is shone is S, and the beam energy Et to the irradiation of per 1 hole represents with formula 1 usually so:

$\mathrm{Et}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\mathrm{Ei}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}[(\mathrm{\αi}\×\mathrm{Pi})\×\mathrm{Wi}]$ Formula 1

By control beam transfer rate α i, peak power Pi, Wi, may command beam energy Et.

Here, the loss decision that causes by the absorption of loss that takes place when forming beam mode in optical system 3 in the existing laser-processing system and optics etc. of beam Propagation rate α i.

As the method that this α i is changed, for example have as shown in Figure 17 will add the method that enters optical system 3 by the object that mask 31, collimating lens 32 constitute.

Among Figure 17, the light of propagating with beam diameter Di is implemented the shaping (making the beam mode that processing stand needs) of beam modes by collimating lens 32 optically focused by mask 31.

At this moment the input beam mode volume and the difference of Output mode volume are the losses that takes place when described beam mode is shaped.

This loss is by the diameter D of mask 31, the focal distance f of collimating lens 32, and mask diameters D and collimating lens 32 leave the distance L decision of mask 31.

For example mask diameters D is big, focal distance f is with distance L about equally the time, and is almost lossless, Output mode volume and input beam mode volume about equally, beam Propagation rate α i increase.

Otherwise mask diameters D is little, focal distance f is long, distance L in short-term, most ofly be loss, with respect to the input pattern volume, the Output mode volume becomes very little, beam Propagation rate α i diminishes.

In the existing system of processing, mask diameters D is the desired beam diameter of processing stand in D, f, three parameters of L, is promptly determined that by the processing aperture focal distance f is fixed, and distance L is mechanically to move, therefore just must displacement L for α i is changed.

But, change distance L and undertaken, so need the time more than the hundreds of ms for change by servomotor.

In addition, peak power Pi is fixing or supposes variable also is with respect to rated value ± 20% degree, and for making its change that the above time of hundreds of ms must be arranged.

Below the schematic diagram with the carbon dioxide laser oscillator of Figure 18 is illustrated.Among the figure, 21 is housing, and 22 is CO for having added laser medium ₂Gaseous mixture, 23 is partially reflecting mirror, 27 is completely reflecting mirror, 28 apertures for the regulation laser oscillation mode, 29 be the laser beam optical axis, 6 laser beams for exporting.

In the carbon dioxide laser oscillator of formation shown in Figure 180,, between electrode 24, form excitation discharge 25, CO by adding the voltage of AC power 23 ₂Gas is excited to upper energy level.At this moment the particle density that discharge evokes is called discharge energy density.In partially reflecting mirror 26 and the resonator inside that completely reflecting mirror 27 constitutes, utilize the induction radiation, the CO that this evokes ₂Amplifying laser is a center outgoing laser beam 6 with laser beam axis 29.

Here, under the situation of the gas laser of carbon dioxide laser, resonator losses is one regularly, and the peak power of laser beam roughly is directly proportional with discharge energy density usually.This discharge energy density roughly is proportional to the power that AC power 23 is added to electrode 24.Therefore, discharge energy density for a change, added voltage between existing laser oscillator control electrode.When overtension, the load increasing to power supply can cause the damage of power failure or electrode.If during brownout, just do not discharge again, the result just become can not outgoing laser beam state.Therefore change the scope of voltage, be generally limited to degree with respect to rated value ± 20%, correspondingly, the peak power of laser beam also can only change ± 20% degree.Because the answer speed that voltage is changed is slow, be stable discharging again,, the above time of necessary hundreds of ms, so each pulse (scope below the maximum oscillation frequency of pulsed laser oscillator, instantaneous ground) is changed under the situation of peak power, can not obtain stable beam energy.

In addition, the laser pulse time width Wi (below be called pulse duration) of output laser width discharge time (to call the discharge width in the following text) that is substantially equal to the discharge of excitation deducts laser generation and postpones the time width that obtains.Its reason is that discharge energy (discharge energy density * time) is lower than laser vibration threshold values during excitation discharge beginning, does not export laser, so the laser generation time started is slower than the excitation discharge time started.(certain this delay is different because of resonator formation, gas composition.) in addition,, provide the time width that drops into electric power to control by to discharge width, specifically, can freely change laser pulse width, this be can instantaneous (scope below the maximum oscillation frequency of pulsed laser oscillator) switching Control Parameter.But, dropping into power and exist and be decided by the restriction of loading, there is the upper limit in pulse duration.

As mentioned above, in existing laser-processing system, because the change difficulty of peak power, so the beam energy utilization is controlled based on the beam Propagation rate α i and the light beam pulse width W i of optical system, when the condition of doing was switched instantaneously, light beam pulse width W i was unique Control Parameter especially.

Below the laser radiation figure is illustrated.

The laser radiation figure can roughly be divided into two classes, promptly after beam irradiation position being positioned the sort of position of opening shown in Figure 19, only with this hole form necessary number S continuously the processing of irradiating laser pulse be impulse train processing; And as shown in Figure 20, when hole count n, hole form necessary number S, beam irradiation position being positioned position of opening, the processing that repeats the action of n * 1 laser pulse of s irradiation is cyclic process.

Impulse train adds formula, if it is Tok (being equivalent to the light beam irradiates off time in the impulse train processing) that the k from each hole is dealt into the lasing time that (k+1) send out required, the pulse duration that s sends out is Ws, positioning time from (j-1) to j hole, then n perforate needed process time of Tb was as shown in Equation 2 when being Tgj:

$\mathrm{Tb}=n\&times;(\underset{K=1}{\overset{s-1}{\mathrm{\&Sigma;}}}\mathrm{Tok}+\mathrm{Ws})+\underset{j=1}{\overset{\mathrm{<figure-callout\; id="2"\; label="n\; Tgj\; Formula"\; filenames="A0381269700211.png"\; state="\{\{state\}\}">n</figure-callout>}}{\mathrm{\&Sigma;}}}\mathrm{Tgj}$ Formula 2

Usually because of Ws＜＜∑ Tok, so have

Formula 3

The mean value of supposing Tok is designated as To, and the mean value of Tgj is designated as Tg, and then the mean value Tba of Tb is

Tba n * (s-1) * To+Tg} ... formula 4

Therefore, process time by laser duration of oscillation To, send out number s and positioning time Ts determined.

On the other hand, establishing the pulse duration that the i to each hole sends out in the cyclic process is Wi, and the positioning time from (j-1) to j hole, then n hole needed process time of Tc was as shown in Equation 5 when being Tgij:

$\mathrm{Tc}=n\&times;\underset{i=1}{\overset{s}{\mathrm{\&Sigma;}}}\mathrm{Wi}+\underset{i=1}{\overset{s}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}\mathrm{Tgij}$ Formula 5

Usually because of Wj＜＜Tgij, so have

Formula 6

If the mean value of Tgij is Tg, then the mean value Tca of Tc is

Tca n * s * Tg ... formula 7

Therefore, in the cyclic process process time by send out number s and positioning time Tg determined.

Here, the difference that cyclic process and impulse train add is described.In the cyclic process, the light beam irradiates off time Tqc in each hole can obtain length, and the thermal impact of machining hole periphery is lowered, and can improve processing quality.

On the contrary, under the situation of impulse train processing, each hole is with laser duration of oscillation To processing, light beam irradiates off time Tqb be shorter than Tqc (Tqc＞＞Tqb), be easy to generate thermal impact to the machining hole periphery.As for process time, if common Tg＞To in consideration formula 4 and the formula 7, then

Tca-Tba=n * (s-1) * (Tg-To)＞0 ... formula 8

Therefore impulse train processing is compared with cyclic process, and process time is short, the productivity ratio height.

In above-mentioned existing laser-processing system, utilize mask diameters control beam diameter, utilize discharge energy density and discharge width and above-mentioned control beam energy such as optical system, utilize arteries and veins group processing and the selection of cyclic process or the laser oscillation frequency control beam irradiation off time that impulse train adds man-hour, thereby guarantee processing quality and productivity ratio.

In addition, the spy opens flat 4-41091 communique and has disclosed the laser processing of processing two kinds of materials, has the laser output of peak power as shown in figure 21, connects the surperficial copper case 14 of processing printed circuit substrate 1, and reprocessing insulating resin 15 is until inner surface Copper Foil 16.

Usually the difficult processing of Copper Foil is so be necessary to strengthen the beam energy of irradiation.On the other hand, because the light reflectivity height of Copper Foil, so if plasma will take place the high laser beam of long-time irradiation peak power, this plasma causes the absorption of laser energy.In addition, Copper Foil has the character that thermal conductivity is big, Yi Reyi is cold.Therefore, it is generally acknowledged, connect suitable method, the method for promptly shining the laser beam (S1 among Figure 21) of high-peak power and short pulse width for making Copper Foil with the big beam energy of short irradiation.

In addition, the processing insulating resin comes easily than above-mentioned Copper Foil, so even little energy also can be processed, but usually because the used insulating resin thickness of printed base plate is thicker than Copper Foil, process the gross energy that all resins is used so be necessary to strengthen.

Yet, if the big beam energy of short irradiation (increase peak power) as above-mentioned Copper Foil, then the insulating resin that thermal conductivity is little can not be uploaded the heat conduction energy at depth direction, and energy is spread on transverse direction, can not get the working depth that purpose requires, resin residue 17 and inner expansion 19 as shown in Figure 24 take place in the result.Therefore it is generally acknowledged that for connecting insulating resin, (S2 among Figure 21～S6) laser beam of low peak power is suitable to shine several.

By the selected various conditions of irradiating laser pulse as mentioned above, can not make the processing quality deterioration, the perforation processing of implementing top layer Copper Foil 12a and perforation processing until the inner surface Copper Foil 12b of insulating resin 11, this is widely known by the people.

But,, can be subjected to restriction as described below if when using existing laser-processing system in the actual processing.

The first, in the existing laser-processing system, lack the method that changes peak power as mentioned above like that significantly, (scope below the maximum oscillation frequency of laser oscillator) that particularly can not be instantaneous changes.

Second, in the existing pulsed laser oscillator, because the relation of power supply capacity etc., the oscillator of output high-peak power laser beam can not be exported the laser beam of long pulse width, otherwise the oscillator of the laser beam of output long pulse width can not be exported the laser beam of high-peak power.

Therefore, existing laser-processing system is difficult owing to process with Figure 22,23 such laser radiation figures so guarantee processing quality and productivity ratio, sacrifice one of them.

Laser radiation figure and machining state when the laser oscillator 2 that Figure 22 is illustrated in Figure 15 uses the existing laser oscillator of laser beam of output high-peak powers and short pulse width (1～15 μ s).

Shown in the S11 among Figure 22, issue permit as the 1st with the laser beam of high-peak power and short pulse width and to penetrate, surperficial Copper Foil 12a is connected.

For processing insulating resin 11a, reduce peak power, shine 4 laser beam S12～S15.In addition, increase the laser beam of depreciation power a little as the 6th with the purpose emission of removing cull.

By processing, can get processing quality to a certain degree based on Figure 22.Yet, want to reduce the 2nd peak power of sending out later as described above significantly, utilize above-mentioned optical system, owing to can not change instantaneously, can not realize impulse train processing.Therefore must make the low cyclic process of productivity ratio and increase to send out to process severally, reduce productivity ratio significantly.For example change average positioning time Tg=0.001 second (1kHz) of needed time in hole count n=10000, consideration condition, when sending out number s=6 and sending out, be 60 seconds process time, compare 30 seconds process times when carrying out impulse train processing (establishing To=0.0005 second (2kHz)) with hypothesis with identical number, and productivity ratio is 1/2.

Laser radiation figure and machining state when the laser oscillator 2 that Figure 23 illustrates Figure 15 uses with the oscillator of the laser beam of existing oscillator output low peak power (below 1/4 of the oscillator of Figure 22) and long pulse width (as 16～150 μ s).

Shown in the S21 among Figure 23, by pulse duration to the laser beam of the 1st lengthening irradiation, strengthen beam energy, in the hope of connecting surperficial Copper Foil 12a, but compare with the 1st of Figure 22, because peak power is below 1/4, for the above reasons, when not dropping into the beam energy more than the 1st the energy shown in Figure 22, it is difficult to connect.Yet, when when improving beam energy and add the degree of long pulse width more than needs, the absorption that plasma causes will take place, energy can not arrive Copper Foil.Therefore, want to connect surperficial Copper Foil 12a, just be necessary to shine the big laser beam of multiple energy (hypothesis can make surperficial Copper Foil 12a connect with 2 in this example).The 3rd issues permit penetrates the laser pulse S23 of low peak power and long pulse width, makes insulating resin penetrate into inner surface Copper Foil 12b.The 4th utilization is higher than the 3rd peak rate and removes resin residue than the laser pulse S24 of short pulse width.

According to top above-mentioned, though can connect finished surface Copper Foil 12a and insulating resin 11a, Copper Foil because energy is too much, is compared with the example of Figure 22, make the processing quality deterioration.In addition, identical with when explanation among Figure 22, because can not instantaneous change peak power, can not do impulse train processing, can only make cyclic process.

As mentioned above, when processing the tellite made from the diverse material laminate of material, be difficult to take into account processing quality and productivity ratio with existing laser-processing system.

In addition, because the kind of tellite is varied, each processing content or be process of resin becomes the processing of Copper Foil and mixed with resin, have nothing in common with each other, thus be difficult with 1 whole processing of laser-processing system enforcement, the funds that equipment investment need be very big.

Summary of the invention

The objective of the invention is to address the above problem, provide tellite can not damage the laser-processing system of productivity ratio ground raising processing quality and the laser processing that uses this device various materials.

For reaching this purpose, the laser-processing system of the 1st invention, possess: change the interelectrode discharge power of input by switching the discharge command pulse that constitutes with assigned frequency, can make the pulsed laser oscillator of the characteristic changing of laser beam, and with the optical system of the described laser beam direction machined object of this laser oscillator output.

Again, optical system has: by making the laser beam transmission of laser oscillator output, the peak power that makes described laser beam is variable optical filtering member and the switch means of switching suitable path that can be by the different optical filtering member of light beam transmissivity.

Again, possess: between electrode, cause the excitation discharge, the laser oscillator of vibration outgoing laser beam, and have by making the described laser beam of described laser oscillator output, make the variable optical filtering member of peak power of described laser beam, with the switch means of switching the suitable path that to pass through the different optical filtering member of light beam transmissivity, with the optical system of laser beam direction machined object.

Utilize the break-make of switch means again, switching can be by the path of optical filtering member, the pulse duration of the laser beam of control impuls vibration simultaneously.

Again, laser processing of the present invention, with changing the interelectrode discharge power of input by switching the discharge command pulse that constitutes with assigned frequency, the laser beam of the variable pulsed laser oscillator output of the characteristic of laser beam is processed, wherein, scope below the maximum oscillation frequency of laser oscillator, according to the material of machined object, processing thickness etc., to a plurality of peak-power of laser pulse and pulse duration and these three conditions of light beam irradiates off time of the instantaneous switching irradiation of each pulse.

Again, for removing of conductor layer, with the output of the maximum peak power that approaches laser oscillator and be that the 1st pulse of the short width of 1～15 μ s is processed; For removing of insulating barrier, with the output of about 1/2～1/10 peak power of above-mentioned the 1st pulse and be that the 2nd pulse of the big width of 16～200 μ s is processed.

Again, variable by the switch discharges command pulse in the laser period of output chien shih peak power of 1 pulse, process with the laser beam of this pulse output.

Process with the laser output of 1 pulse in long the 2nd zone of about 1/2～1/10 peak power in the 1st zone of the short time with the roughly largest peaks power of laser oscillator and 1～15 μ s, above-mentioned the 1st zone and 16～200 μ s again.

Description of drawings

The schematic diagram that Fig. 1 uses for the laser-processing system of explanation example 1.

Fig. 2 illustrates the state diagram of the means of control laser radiation figure in the laser-processing system of example 1.

Fig. 3 illustrates laser radiation pictorial diagram used in the laser processing of the laser-processing system of utilizing example 1.

The schematic diagram that Fig. 4 utilizes the laser processing state of the laser radiation figure of Fig. 3 to use for explanation.

The schematic diagram that Fig. 5 uses for the laser-processing system of explanation example 2.

Fig. 6 illustrates the state diagram of the beam Propagation rate variation that is caused by object.

Fig. 7 illustrates the pie graph of the formation of object.

Fig. 8 illustrates the state diagram of the variation of the beam Propagation rate that caused by object and pulse duration.

The schematic diagram that Fig. 9 uses for the laser-processing system of explanation example 2.

The schematic diagram that Figure 10 uses for the laser-processing system of explanation example 3.

The schematic diagram that Figure 11 uses for the laser-processing system of explanation example 4.

The schematic diagram that Figure 12 uses for the means of control laser radiation figure in the laser-processing system of explanation example 4.

The laser-processing system that Figure 13 illustrates example 4 is used for the illumination pattern schematic diagram that impulse train adds the laser beam in man-hour.

Figure 14 is the schematic diagram of the perforate processing usefulness of the general tellite of explanation.

The schematic diagram that Figure 15 uses with laser-processing system for the perforate of the existing tellite of explanation.

The profile of the tellite that Figure 16 uses for the crudy of explanation laser beam drilling processing.

Figure 17 illustrates the pie graph that constitutes of the object of being made up of mask, collimating lens.

Figure 18 is explanation CO ₂The pie graph that laser oscillator is used.

Figure 19 is the laser radiation figure of explanation as the impulse train processing usefulness of the perforate laser processing of existing tellite.

The laser radiation figure that Figure 20 uses as the cyclic process of the perforate laser processing of existing tellite for explanation.

Figure 21 is the schematic diagram of existing laser radiation figure and the profile of tellite.

Figure 22 is the schematic diagram of existing laser radiation figure and the profile of tellite.

Figure 23 is the schematic diagram of existing laser radiation figure and the profile of tellite.

Figure 24 is a profile of representing the tellite of crudy in the past.

Embodiment

Example 1

Fig. 1,2 relates to example 1, the schematic diagram that Fig. 1 uses for explanation laser-processing system of the present invention, the schematic diagram that Fig. 2 uses for the means of explanation control laser radiation figure of the present invention.

Among Fig. 1,6a, 8a represent the laser beam and the laser radiation figure of laser oscillator 2A output, and 7a, 9a represent to penetrate figure with laser beam and laser after optical system 3 shapings, and all the other and Figure 15 same section mark same-sign are also omitted explanation.

Among Fig. 2,41a, 41b are discharge command pulse group, and 42a, 42b are the discharge power impulse train, 43a.43b is a discharge energy, and 44a, 44b are the laser beam energy of output.

Again, fh, fl represent ac power frequency, and Iu, Id represent effective discharge energy density, Nu, Nd represent average discharge power density, and Ds, Dl represent the width that discharges, and Pu, Pd represent peak power, Ws, Wl indicating impulse width, Ls, Ll represent that laser generation postpones.

As described in the prior art, at CO ₂In the such gas laser oscillator of laser oscillator, the peak power and the pulse duration of the laser beam of oscillator output for a change are one regularly in resonator losses, control discharge energy density and discharge width.Because discharge energy density is directly proportional with dropping into power, so in prior art, the interelectrode voltage that applies is changed discharge energy density by changing.

The laser oscillator that this example relates to, be conceived to drop into power and be divided into instantaneous implementation power and time averaging average power, and the peak power of laser beam is arranged by time averaging average power, at voltage is on the basis of certain (it is certain to carry out discharge energy density), discharge power umber of pulse by the control time per unit is controlled average discharge power density, and the peak power of laser beam is changed.In other words, according to material, the material of the processed part of tellite constitute, processing thickness etc., to these 3 conditions of a plurality of peak-power of laser pulse, pulse duration and light beam irradiates off time of the instantaneous change irradiation of each pulse.

Here, in prior art,, so effective discharge energy density and average discharge power density are a pair of proportionate relationships, utilize change in voltage that effective discharge energy density is changed, control average discharge power density because the discharge power umber of pulse is certain.

Below with Fig. 2 action is described.

At first, when the discharge command pulse is provided with time interval 1/fp, and it synchronously drops into discharge power pulse (step fp) from AC power between electrode.The height of this discharge power pulse is effective discharge energy density I of moment, does to be average discharge power density N behind the time average.

If it is certain to be added to interelectrode voltage, then effectively discharge energy density is certain, and the discharge power umber of pulse m that time per unit drops into is many more, and average discharge power density is high more, and the peak power of laser beam is high more.

For example, when the discharge command pulse was provided with short time interval (1/fh), synchronous with it, AC power dropped into discharge power pulse (the discharge power umber of pulse of time per unit input increases) with high-frequency fh, average discharge power density Nu increases, the laser beam of output high-peak power Pn.

Otherwise, when the discharge command pulse was provided with long-time interval (1/fl), synchronous with it, AC power dropped into discharge power pulse (the discharge power umber of pulse that time per unit drops into reduces) with low frequency fl, average discharge power density Nd lowers, the laser beam of output low peak power P d.

As mentioned above, by changing the time of dropping into power to electrode, the pulse duration of laser beam is changed.

The making time width D of this power is represented with following formula:

D=(1/fp) * m ... formula 9

Therefore, the control by above-mentioned discharge command pulse interval 1/fp and discharge power umber of pulse m can obtain pulse duration arbitrarily.

As mentioned above, obtain the peak power of laser beam with the modulation ac power frequency in this example, obtain any laser pulse by the pulse duration that changes the time of dropping into power and control laser beam.

Specifically, provide the time interval and discharge command pulse number of discharge command pulse by control, obtain laser pulse arbitrarily.

Again, according to the present invention, employing is adopted than low peak power when long pulse width than short pulse width when high-peak power, thereby has the effect of the range of choice of expansion impulse waveform in certain power supply load range.

Utilize above-mentioned control that each laser pulse is changed peak power and pulse duration arbitrarily, obtain laser radiation figure 8a arbitrarily, by optical system resulting laser radiation figure is carried out beam-shaping, being sent to the processing object thing as laser radiation figure 9a is that tellite 1 is processed.

Impulse train processing method with above-mentioned laser-processing system below is described.

As an example, the following describes the situation of the tellite that the processing printed base plate identical with Figure 21 promptly be made of the 1st laminar surface Copper Foil 12a, the 2nd layer of insulating resin 11a, the 3rd layer of inner surface Copper Foil 12b.

Fig. 3 is the schematic diagram of the illumination pattern of expression laser beam, the schematic diagram that Fig. 4 uses for explanation machining status at this moment.

Among Fig. 3, S31～S33 is the laser beam of the 1st of each hole～3rd, each cartographic represenation of area beam energy.P is a peak power, and W is a pulse duration, and To is lasing time, and Tg is positioning time.

Among Fig. 4,12a is surperficial Copper Foil, and 11a is an insulating resin, 12b is the inner surface Copper Foil, and 20a is scheduled to Working position, and 14a is the blind hole after processing, S31～S33 respectively is the 1st～3 laser pulse shape, and a1～a3 respectively penetrates the processed portion of laser beam processing for issuing permit by the 1st～3.

This example uses laser radiation figure shown in Figure 3, material and material according to tellite constitute, process thickness etc., by peak power, pulse duration and these conditions of light beam irradiates off time to the instantaneous switched laser bundle of each pulse, use the impulse train processing method simultaneously, measure the shortening of process time.

Be prerequisite with the material that in prior art, illustrated and the pass of laser beam below, the laser processing of this example is described with Fig. 3, Fig. 4.

At first, shine the 1st laser beam S31, as the 1st layer of laser pulse that Copper Foil 12a uses of processing, can satisfy the 1st layer of Copper Foil that Copper Foil is removed condition for stably connecting, the laser pulse of irradiation high-peak power (about 1～3kW) and short pulse width (1～15 μ s).

Then, shine the 2nd laser beam S32, as the 2nd layer of laser pulse that insulating resin 11a uses of processing, remove condition and boost productivity the laser pulse of irradiation low peak power (about 0.05～0.5kW) and long pulse width (80～200 μ s) for satisfying insulating resin.

This laser pulse is different with Figure 21, adopt the low peak power below 1/6 of the 1st laser pulse and be the laser pulse of its long pulse width more than 5 times, therefore in Figure 21, must shine multiple laser beam, but adopt the present invention as long as 1 of irradiation just can for connecting insulating resin.That is, suppress energy expansion diametrically, come to inject energy to add long pulse width, thereby can the processing aperture be remained unchanged with 1 perforation insulating resin at depth direction with extreme reduction peak power.As a result, reduce a number unchangeably, save the unnecessary light beam irradiates off time, so productivity ratio is improved owing to guarantee processing quality.

Then, shine the 3rd laser beam S33, the laser pulse that the insulation fat 11a that does not eliminate clean as the 2nd laser beam S32 of processing uses, if the irradiation macro-energy can be caused the damage of internal layer Copper Foil, so irradiation energy E3 is lower for well, again, in order to suppress resin residue, peak power should be sent out higher than the 2nd, and therefore irradiation is than the laser pulse of the 2nd high slightly peak power (about 0.1～1kW) and short pulse width (about 1～30 μ s).

As mentioned above, in this example, under the situation of above-mentioned tellite, utilize 3 laser beam irradiation can guarantee good processing quality, can lower simultaneously and send out number.

In sum, in this example, material and material according to tellite constitute, to peak power and pulse duration the scope optimization the frequency of oscillation of pulsed laser oscillator below of each pulse with laser beam, instantaneous change peak power, with the impulse train processing and implementation laser radiation figure of Fig. 3 for example, to obtain the effect that processing quality and productivity ratio two aspects all improve.

For example, hole count n=10000, the consideration condition is switched average positioning time To=0.0005 second (2kHz) of necessary time, send out under the situation that number s=3 send out, be 15 seconds process time, compares with the cyclic process with the laser radiation figure of Figure 20, shortens to 45 seconds.This adds man-hour wanting that the tellite that utilizes the unlike material lamination to be processed into is carried out the high density perforate, can bring into play its effect especially.

Again, processing is described to blind hole above, but be used in through hole and add man-hour too, by with peak power, the pulse duration of laser beam and shine the off time and each pulse is made its optimization, thereby has the effect that improves processing quality and productivity ratio according to the scope below the material of tellite, the frequency of oscillation that material is formed in pulse oscillator.

Again, though above make an explanation with regard to impulse train processing, certainly also applicable to cyclic process, compare with impulse train processing, production efficiency is on the low side to a certain extent, but has the effect that can more stably obtain good processing quality.

Can be used in the processing method of using impulse train processing and cyclic process in the lump again.Promptly, not only be conceived to the light beam irradiates off time, material and material according to tellite constitute, make peak-power of laser pulse and pulse duration optimization, and as changing the means of shining the off time significantly, separately use impulse train processing and cyclic process, can stably obtain good processing quality thereby have not only, and the effect that can boost productivity.

Again, the laser-processing system of the tellite of the application of the invention can be implemented the processing of multiple tellite with 1 laser-processing system.

Example 2

Above-mentioned example 1 is for average discharge power changes the peak power of laser beam with the discharge width and the situation of pulse duration is made an explanation by changing, but also can change the beam Propagation rate of optical system.Therefore, this example is conceived to the beam Propagation rate of optical system.

Fig. 5, Fig. 6, Fig. 7, Fig. 8 are relevant with example 2, the schematic diagram that Fig. 5 uses for explanation laser-processing system of the present invention, the schematic diagram that Fig. 6 uses for the means of explanation control laser radiation figure, Fig. 7 illustrates the schematic diagram as one of the object of the means use of control laser radiation figure example, and Fig. 8 is the action diagram of object.

Among Fig. 6,45a, 45b are the laser beam energies after being shaped by optical system.

Among Fig. 7, Fig. 8,33 for the control unit that can change the laser beam transfer rate at any time be object, the 34th, be used for suitably change to incide the optics speed-sensitive switch element in path of the laser beam 6b of object 33,35 half-reflecting mirrors that have nothing in common with each other for the beam Propagation rate (light beam transmissivity) of laser peak power of the laser that can change incident, 36 for being used for absorbing the damper of half-reflecting mirror 35 laser light reflected.For convenience of explanation, illustrate as 37a, 37b, 38c with the laser behind switch element 34a, the 34b alternative routing again.

Below explanation outputs to the peak power of laser beam of processing stand and the variation of pulse duration from the optical system of this example.

The laser peak power when at first illustrating that with Fig. 6 change changes the beam Propagation rate and the action of pulse duration.

The beam Propagation rate of optical system for example regularly 100% (usually less than 50%, but be simplified illustration, be assumed to be 100%) one, remaining untouched from the laser beam of laser oscillator output is transferred to processing stand with identical peak power and pulse duration.

Here, when the object of the beam Propagation rate that makes it by having regulation, in the laser beam of laser oscillator output, A% transmission object, B% is absorbed by object, and C% is by object reflection (A+B+C=100%).As a result, be the laser beam of A% by what object was output, the peak power of output changes.Between the laser beam 44a period of output of laser oscillator for example shown in Figure 6 output, when reducing the beam Propagation rate, obtain peak power from Pu change to Pm (＜Pu), pulse duration still is the laser beam 45a of Ws.

Again, in the light beam of the laser beam 44b that laser oscillator is exported transmitted on the way, make the beam Propagation rate was 0% o'clock instantaneously, just obtained peak power and kept Pd constant, and pulse duration is from W ₁Change to Wm (＜W ₁) laser beam 45b.

As mentioned above, in this example,, thereby obtain peak power and pulse duration arbitrarily by the beam Propagation rate of control optical system.But for the laser beam of conversion laser oscillator output to obtain laser pulse arbitrarily, largest peaks power determined with the longest pulse duration laser beam by laser oscillator output, can not utilize optical system to be transformed to peak power or pulse duration greater than it.

Specifically, the means that change as the beam Propagation rate that makes above-mentioned optical system and pulse duration one of example, describe with the object 33 that can change the laser beam transfer rate at any time shown in Figure 8.

Object 33 is made of speed-sensitive switch element 34a～34d, the transmissivity of optics different half-reflecting mirror 35a～35b and damper 36.In addition, be input to the peak power of laser beam of object 33 and pulse duration and be assumed to be necessarily and describe, again, the action of supposing the speed-sensitive switch element is in the deflection of conducting time.

At first, when switch element 34a was conducting (ON), laser beam 6b intactly remained laser beam 37a and is sent to switch element 34c.At this moment switch element 34c is for ending (OFF) if make, and then laser beam 36a intactly is sent to next switch element 34d.At switch element 34d, instantaneous when OFF switches to ON in light beam transmits, then the laser beam during the OFF is 7b, but laser-beam deflection during the ON shines damper 36.When time of OFF in short-term, the result obtains the laser pulse 7b1 of high-peak power and short pulse width.

Secondly, switch element 34a is OFF, when switch element 34b is ON, and laser beam 6b by the deflection of switch element 34b institute, is sent to half-reflecting mirror 35a by switch element 34a.If the transmissivity of half-reflecting mirror 35a is at for example 50% o'clock, then laser beam 37b for its peak power be 6b half, and the identical laser beam of pulse duration.Laser beam 37b is sent to switch element 34c, is deflected when 34c conducting (ON), is sent to switch element 34d.Carry out the action identical with above-mentioned explanation at switch element 34d, the result obtains laser pulse 7b2.

Then, when switch element 34a, 34b were OFF, laser beam 6b was sent to pellicle mirror 35b by switch element 34a, 34b.The transmissivity of supposing pellicle mirror 35b for example is 25%, laser beam 37c become its peak power be 6b 1/4 and the identical laser beam of pulse duration.Then, laser beam 37c is sent to switch element 34d.Carry out the action opposite at switch element 34d with the action of above-mentioned explanation.Be that laser beam is deflected during the ON of switch element 34d, the laser beam during the OFF passes through, and shines damper 36.When the time of ON was long, the result obtained the laser beam 7b3 of low peak power and long pulse width.

Again, the method for 3 kinds of peak powers of control shown in the above-mentioned explanation, but the peak power of control more than 2 kinds or 4 kinds that also can use the same method obtain the laser pulse of peak power and pulse duration arbitrarily.

By above-mentioned object is inserted optical system, the ON/OFF of high speed switches light becomes the laser pulse of peak power and pulse duration arbitrarily with this transforming laser with laser oscillator output in this example.

As above-mentioned optical system is installed to laser-processing system shown in Figure 5, then obtain and the identical effect of effect shown in the example 1, promptly material and the material according to tellite constitutes, each pulse is made peak power, pulse duration and the light beam irradiates off time optimization of laser beam, with this be improved processing quality and the such effect of productivity ratio.

In addition, also can constitute the combined system of processing (Fig. 9) of laser oscillator that illustrates in above-mentioned optical system and the example 1.Its effect is to change the peak power and the pulse duration of laser beam thinner, by a larger margin.

Therefore, as use above-mentioned laser-processing system, then according to the material of tellite and the formation of material, enlarge range of choice more, each pulse is made peak power, pulse duration and the beam energy optimization of laser beam, thereby more complicated material is constituted the sort of effect of also can be improved processing quality and productivity ratio.

Example 3

In the above-mentioned form 1,2 laser-processing system that constitutes with 1 laser oscillator is described, but the laser-processing system that constitutes with the peak power of the laser beam more than at least 2 laser oscillator different with pulse duration is provided in this example.

Figure 10 illustrates the formation schematic diagram of laser-processing system of the present invention.Among the figure, 2C, 2D are respectively the different laser oscillator of laser generation output, 3C, 3D are optical system, and 6c, 8c, 6d, 8d are respectively the laser beam and the laser radiation pattern of laser oscillator 2C, 2D output, and 7d, 7d are the laser beam after being shaped by optical system 3C, 3D.

The action of Figure 10 then is described.

Laser oscillator 2C is for example for connecting the best high-peak power of Copper Foil output and the laser pulse 6c of short pulse width, and laser oscillator 2D connects the low peak power that for example insulating resin output is best and the laser pulse 7d of long pulse width.Laser pulse 8c and 8d are sent to by optical system 3C, 3D respectively and shine in tellite 1.At this moment, make Copper Foil on the laser beam 7c irradiation tellite 1 by control, laser beam 7d shines insulating resin.That is, by control, under the situation of the tellite of Figure 21, make the 1st to issue permit and penetrate laser beam 7c, the 2nd issues permit penetrates laser beam 7d, and the 3rd peak power that makes the laser beam of laser oscillator 2C output reduces shines, thus with the effect of the example 1 the same processing quality that is improved.

Example 4

Figure 11, Figure 12 relate to example 4, and Figure 11 is the schematic diagram that is used for illustrating laser-processing system of the present invention, and Figure 12 is the schematic diagram that is used for illustrating the means of controlling laser pulse shape of the present invention.

Among Figure 11,46a～e is discharge command pulse group, and 47a～e is the discharge power impulse train, the discharge energy of 48a～e for dropping into, and 49a～e is the laser beam energy of output.

The basic consideration of this example is conceived to, the laser beam 6e of the laser oscillator 2E of Figure 11 output is as implementing as described in the form 1, under resonator losses is certain situation, determined by average discharge power density and discharge width, but midway also can be suitable in laser generation.That is to say, roughly control by the laser pulse shape of implementing as shown in figure 12 in the action, obtain laser radiation figure 8e arbitrarily.

Below the action of Figure 12 is described.

Figure 12 is applicable to the basic consideration method of above-mentioned example 1, promptly with resonator losses as certain, utilize average discharge power density control peak power respectively, by discharge width control impuls width.Again, identical with example 1, as concrete control method, be adopted as and change average discharge power density modulation ac power frequency, for a change discharge width and change the time method that drops into power.

At first, when discharge command pulse 46a was provided with high frequency, the discharge power arteries and veins number of time per unit input just increased, and can obtain the 48a of high average discharge power density.With respect to this discharge energy 48a (N1 * T1), after laser generation postpones L1, the beam energy 49a of output high-peak power (P1 * W1).

Then when do not set in advance the time difference when the low slightly discharge command pulse 46b of frequency is provided continuously (light beam irradiates off time), just drop into discharge power pulse 47b, obtain discharge energy 48b (N2 * T2), current laser vibration does not have and postpones, with the 49a of front output beam energy 49b (P2 * W2) conjointly.

Below similarly, when discharge command pulse 46c, 46d, 46e are provided with not setting in advance the time difference continuously, (((N5 * T5) is with the 49b of front output beam energy 49c (P3 * W3), 49d (P4 * W4), 49e (P5 * W5) conjointly for N4 * T4), 47e for N3 * T3), 47d to obtain discharge energy 47c accordingly.The result obtains mixing the laser pulse shape of 5 kinds of any peak powers.

In addition, identical with example 2, utilize optical system 3E that resulting laser radiation figure 8e is carried out light beam and form, also can suitably utilize optical system to change the laser beam waveform and make it become laser radiation figure 9e.Promptly pass through the waveform of the switch motion of controlling object thing in the laser generation way, thereby obtain mixing the laser pulse shape of the such a plurality of peak powers of above-mentioned explanation with the laser beam of explanation in the control example 2.

As mentioned above, in laser generation way, use the consideration method identical, obtain mixing the laser pulse shape of a plurality of peak powers with example 1,2.But compare with example 1,2, if do not implement more high speed and more stable control, then the deviation of each pulse might increase.

Below to using above-mentioned laser-processing system to be illustrated as the processing method of means.

The processing method of this example is the situation of the condition of setting laser impulse waveform in more detail in the processing method of example 1.

Figure 13 illustrates laser-processing system of the present invention is used in the schematic diagram of illumination pattern that impulse train adds the laser beam in man-hour.

Among Figure 13, establish that v peak power is Piv in the u kind peak power that is present in the 1st, when the time width that keeps with Piv was Wiv, the beam energy Ei that then shines the laser beam that i sends out was given by following formula:

$\mathrm{Ei}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(\mathrm{Piv}\&times;\mathrm{Wiv})$ Formula 10

Here, Piv, Wiv are the Control Parameter that can switch instantaneous (time below 1/2 of laser pulse width) among the present invention, switch with said method according to processing content.

Among Figure 13, S41, S42 are respectively the P11 * W11 in the 1st, the illuminating laser beam of P12 * W12, and S43 is the illuminating laser beam of P21 * W21 of the 2nd.

Below action is described.

Each illumination beam of S31～S33 shown in illumination beam S41～S43 and the example 1 uses accordingly.Be that S41 is high-peak power and short time width, S42 is low peak power and long-time width, and S42 is the peak power of a little higher than S42 and the laser beam of short pulse width.Utilize laser beam separately, obtain with example 1 in the roughly the same processing result of processing method of explanation.Promptly connect finished surface Copper Foil 12a, connect processing insulating resin 11a, inner surface Copper Foil 12b is removed the resin residue thing with no damage with S43 with S42 with S41.

Again, because S41 and S42 are same laser pulses, so needed the number in every hole reduced to 2 from 3.Therefore have the effect that reduces the light beam irradiates off time, more shorten n the process time that perforate is required than example 1.For example in the example shown in the example 1, be 10 seconds process time, compares with the impulse train processing of example 1, is expected to shorten 5 seconds process time, and productivity ratio improves 1.5 times.

As mentioned above,, improve processing quality, reduce again and send out number (reducing the light beam irradiates off time), therefore also improved productivity ratio by using the laser-processing system of control laser pulse shape.

In addition, has acquisition effect aspect inaccessiable processing quality and the productivity ratio two in existing laser-processing system.

Industrial utilizability

As mentioned above, laser processing device of the present invention is applicable to the perforate processing to machined objects such as printed base plates.

Claims (8)

1. a laser-processing system is characterized in that possessing

Change the interelectrode discharge power of input by switching the discharge command pulse that constitutes with assigned frequency, can make the pulsed laser oscillator of the characteristic changing of laser beam, and

Optical system with the described laser beam direction machined object of this laser oscillator output.

2. laser-processing system as claimed in claim 1, it is characterized in that, optical system has: by making the laser beam transmission of laser oscillator output, the peak power that makes described laser beam is variable optical filtering member and the switch means of switching suitable path that can be by the different optical filtering member of light beam transmissivity.

3. laser-processing system is characterized in that possessing:

Between electrode, cause the excitation discharge, the laser oscillator of vibration outgoing laser beam, and

Have by making the described laser beam of described laser oscillator output, make the variable optical filtering member of peak power of described laser beam, with the switch means of switching the suitable path that can pass through the different optical filtering member of light beam transmissivity,

Optical system with the laser beam direction machined object.

4. as claim 2 or 3 described laser-processing systems, it is characterized in that, utilize the break-make of switch means, switching can be by the path of optical filtering member, the pulse duration of the laser beam of control impuls vibration simultaneously.

5. laser processing is used by switching the discharge command pulse that constitutes with assigned frequency to change and drop into interelectrode discharge power, and the laser beam of the variable pulsed laser oscillator output of the characteristic of laser beam is processed, it is characterized in that,

Scope below the maximum oscillation frequency of laser oscillator is according to the material of machined object, processing thickness etc., to a plurality of peak-power of laser pulse and pulse duration and these three conditions of light beam irradiates off time of the instantaneous switching irradiation of each pulse.

6. laser processing as claimed in claim 5 is characterized in that,

For removing of conductor layer, with the output of the maximum peak power that approaches laser oscillator and be that the 1st pulse of the short width of 1～15 μ s is processed;

For removing of insulating barrier, with the output of about 1/2～1/10 peak power of above-mentioned the 1st pulse and be that the 2nd pulse of the big width of 16～200 μ s is processed.

7. laser processing as claimed in claim 5 is characterized in that, and is variable in the laser period of output chien shih peak power of 1 pulse by the switch discharges command pulse, processes with the laser beam of this pulse output.

8. laser processing as claimed in claim 7, it is characterized in that, process with the laser output of 1 pulse in long the 2nd zone of about 1/2～1/10 peak power in the 1st zone of the short time with the roughly largest peaks power of laser oscillator and 1～15 μ s, above-mentioned the 1st zone and 16～200 μ s.

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