CN119368947A - Laser drilling method and system - Google Patents

Abstract

The invention discloses a laser drilling method and a laser drilling system, and relates to the technical field of laser drilling. The laser drilling method comprises the steps of using a pulse laser to drill holes, and forming micropores with the aperture of 10-100 mu m on a material to be processed by adjusting the waveform of a pulse train sent by the pulse laser and shaping the pulse train beam, wherein the pulse train output frequency of the pulse laser is 1-20kHz, the wavelength is 257-1064nm, and the pulse train comprises at least two parts of sub-pulse waveforms, wherein the sub-pulse energy in the former part of sub-pulse waveforms is larger than the sub-pulse energy in the latter part of sub-pulse waveforms according to the sequence. The drilling method of the invention firstly utilizes the high-energy pulse train to effectively remove the materials, and then utilizes the low-energy pulse train to reduce the damage to the bottom surface materials. According to the laser drilling system provided by the invention, the pulse train beam is shaped in the shaping system to realize the transformation of different beams, so that high-quality drilling with different apertures and high conicity can be realized.

Description

Laser drilling method and system

Technical Field

The invention relates to the technical field of laser drilling, in particular to a laser drilling method and system.

Background

The IC carrier board (IC Substrate) is a subdivision field of PCB industry, mainly used for bearing IC, and the circuit is distributed in the IC carrier board for conducting signals between chip and circuit board, besides the bearing function, the IC carrier board also has additional functions of protecting circuit, special line, designing heat dissipation path, building modular standard of components, etc. The high-end IC carrier board (ABF carrier board) is mainly used for packaging chips with high operation performance such as CPU, GPU, FPGA, ASIC and the like, and is a basic stone for big data and artificial intelligence.

The IC carrier plate is formed by stacking materials with different thicknesses, different signal layers are communicated through micro holes, and the laser drilling of the carrier plate means that the micro holes are processed on the carrier plate by using a laser technology.

The aperture of a micro hole machined by the current carrier plate laser drilling technology is 70-150 mu m, and is mainly machined by adopting a CO ₂ laser and a nanosecond ultraviolet laser, and pretreatment (brown oxidation, black oxidation, windowing, film pasting, surface copper thinning and the like) operation is required. Along with the explosion of big data and artificial intelligence and the increasing requirement of an IC carrier board of an advanced packaging technology, the method is mainly characterized in that the number of IO points of the carrier board is increased and is more and more dense, and further, the aperture of micro holes of the carrier board is required to be further reduced, and the aperture of laser drilling holes of the next generation carrier board is between 10 and 100 mu m. The current mainstream laser drilling technology has complex operation, materials are easy to delaminate, and the hole diameter of the drilled holes cannot meet the requirements of the next generation of carrier plates.

Disclosure of Invention

The invention aims to provide a laser drilling method and a system capable of processing the aperture of 10-100 mu m, in particular 20-70 mu m.

In order to solve the problems, the invention provides the following technical scheme:

In a first aspect, the invention provides a laser drilling method, which comprises the steps of drilling by using a pulse laser, forming micropores with the aperture of 10-100 μm on a material to be processed by adjusting the waveform of a pulse train sent by the pulse laser and shaping the pulse train beam, wherein the pulse train output frequency of the pulse laser is 1-20kHz, the wavelength is 257-1064nm, and the pulse train comprises at least two parts of sub-pulse waveforms, and the sub-pulse energy in the former part of sub-pulse waveforms is larger than the sub-pulse energy in the latter part of sub-pulse waveforms in sequence.

Preferably, the pulse train comprises two parts of sub-pulse waveforms, wherein the sub-pulse energy in the former part of the sub-pulse waveforms is greater than or equal to 70% of the total energy of the pulse train, and the sub-pulse energy in the latter part of the sub-pulse waveforms is less than 30% of the total energy of the pulse train.

Preferably, the wavelength of the output of the pulse laser is 257-1064nm, and more preferably 532nm.

Preferably, the pulsed laser is a femtosecond, picosecond or nanosecond laser.

Preferably, the pulse width of the pulse laser is less than 100ns.

Preferably, the pulse width of the pulse laser is 2-20ps.

Preferably, the pulses emitted by the pulse laser are output in the form of pulse trains.

Preferably, the number of pulses in the pulse train emitted by the pulse laser is greater than 50.

Preferably, the number of pulses in the pulse train emitted by the pulse laser is 50-300.

Preferably, the pulse train is of duration greater than 10 μs. For example, the pulse train may last for a period of 20 μs, 50 μs, 80 μs, 100 μs, 150 μs, 200 μs, 300 μs, etc. The duration of the pulse train can be determined by one skilled in the art based on the borehole board and specifications.

In a second aspect, the present invention provides a laser drilling system for performing the laser drilling method of the first aspect.

Preferably, the system comprises a pulse laser, a shaping system, a galvanometer system, a focusing system, a motion control system, a quality monitoring system, a software system and an auxiliary blowing module, wherein Gaussian pulses sent by the pulse laser are incident into the focusing system through the shaping system and the galvanometer system, laser is emitted from the focusing system to be focused on the surface of a material to be processed, the shaping system is used for shaping light beams, the motion control system is used for controlling the motion of the material to be processed on a processing plane, the auxiliary blowing module is used for cooling and blowing the surface of the processed material, the quality monitoring system is used for monitoring the quality of drilling holes in the processing process, and the software system is used for controlling the process pretreatment and the drilling process.

Preferably, the laser drilling system further comprises a workbench, the material to be processed is arranged on the workbench, and the auxiliary blowing module is arranged on the workbench.

Further, the laser drilling system further comprises a 45-degree reflecting mirror, wherein the 45-degree reflecting mirror is arranged between the shaping system and the focusing system and is used for converting the Gaussian pulse into a 90-degree direction and then making the Gaussian pulse enter the focusing system.

Further, the shaping system includes diffractive optics including, but not limited to DOE (Diffractive Optical Elements), phase plates, aperture stops, microlens arrays (LENSARRAY), aspheric lenses to convert the gaussian beam emitted by the pulsed laser into a flat top beam or a flat top-like beam.

The shaping system further comprises a beam expanding collimating lens and a vibrating lens, the focusing system is a field lens, and a Gaussian beam emitted by the pulse laser enters the vibrating lens along the horizontal direction through the diffraction optical device and the beam expanding collimating lens, and is vertically incident into the field lens after being converted into the 90-degree direction through the vibrating lens and the 45-degree reflecting lens.

Compared with the prior art, the invention has the following technical effects:

The laser drilling method provided by the invention has the advantages that the waveform of the pulse train emitted by the pulse laser is regulated, and the pulse train beam is shaped, the output pulse train comprises at least two pulse waveforms, and the sub-pulse energy in the former part of the sub-pulse waveforms is larger than the sub-pulse energy in the latter part of the sub-pulse waveforms according to the sequence. The invention utilizes the output of high-energy sub-pulse to rapidly remove the surface layer material, and then outputs low-energy sub-pulse to avoid damaging the bottom layer material, thus obtaining micropores with the aperture of 10-100 mu m, especially micropores with the aperture of 20-70 mu m, and meeting the technical requirements of the IC carrier plate. The hole obtained by the laser method has the advantages of no heat affected zone, difficult layering of materials, no problems of molten materials, volcanic vent, residual glue at the bottom of the hole, protruding glass fiber and the like, clean bottom of the hole, hole washing effect, no need of pretreatment and the like. The action mechanism of the whole laser and the material is mainly cold processing removal, so that the influence caused by the heat effect is greatly reduced, and the taper of the drilling hole and the smoothness of the bottom surface are ensured.

According to the laser drilling system provided by the invention, the waveform of the pulse train emitted by the pulse laser is regulated by the shaping system, and the pulse train beam is shaped, so that the conversion of different beams is realized, and the drilling of different apertures can be realized. The laser drilling system for drilling the carrier plate only needs the steps of focusing the light beam and cooling and blowing, does not need other pretreatment and post-treatment work, has simple drilling process and greatly improves the drilling efficiency.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a laser drilling system according to an embodiment of the present invention;

Fig. 2 is a schematic diagram of a laser drilling method for drilling holes in a carrier according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of pulse waveforms of a laser drilling method according to an embodiment of the present invention;

fig. 4 is a diagram showing a processing effect of the laser drilling system for drilling holes on a carrier plate according to the embodiment of the present invention.

Reference numerals

1 Software system, 2 quality monitoring system, 3 pulse laser, 4 plastic system, 5 mirror, 6 focusing system, 7 carrier plate, 8 auxiliary blowing module, 9 workstation.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, in which like reference numerals represent like components. It will be apparent that the embodiments described below are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

It should be understood that the terms "comprises" and "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It is also to be understood that the terminology used in the description of the embodiments of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of embodiments of the invention. As used in the specification of the embodiments of the invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Example 1

Referring to fig. 1, an embodiment of the present invention provides a laser drilling system, which includes a software system 1, a quality monitoring system 2, a pulse laser 3, a shaping system 4, a transmitter 5, a focusing system 6, a carrier plate 7, an auxiliary blowing module 8, and a workbench 9. The software system 1 is used for performing operations such as process pretreatment and control of a drilling process, the quality monitoring system 2 is used for monitoring the drilling quality in the machining process, gaussian pulses emitted by the pulse laser 3 are incident into the focusing system 6 through the shaping system 4, the pulse laser is emitted from the focusing system 6 to be focused on the surface of a material to be machined, the material to be machined in the embodiment is a carrier plate 7, and the auxiliary blowing module 8 is used for cooling and blowing the surface of the machined material.

In a specific embodiment, the workbench 9 is provided with a processing station, and the carrier plate 7 is disposed on the processing station during processing, and the auxiliary blowing module 8 is disposed on the workbench 9.

As can be seen from the figure, the shaping system 4 is configured to shape the beam, and the shaping system 4 includes a diffraction optical device, where the diffraction optical device can convert the gaussian beam emitted by the pulse laser 3 into a flat-top beam or a quasi-flat-top beam with sharp edges, clear edges and sharp tapers, and the taper is close to 90 degrees, so as to ensure the drilling effect. Suitable diffractive optics include, but are not limited to, DOEs, phase plates, aperture stops, microlens arrays, aspheric lenses, etc., to improve spot uniformity, drilling quality by adjusting the phase distribution, intensity distribution of the beam.

In a specific embodiment, the shaping system 4 further includes an optical lens necessary for expanding, contracting and collimating the gaussian pulse emitted by the pulse laser 3.

In a specific embodiment, the laser drilling system further includes a reflecting mirror 5, where the reflecting mirror 5 is a 45 ° reflecting mirror, and the 45 ° reflecting mirror is disposed between the shaping system 4 and the focusing system 6, and is configured to convert the laser beam into a 90 ° direction and then make the laser beam enter the focusing system 6.

In a specific embodiment, the focusing system 6 is a field lens, and the focusing system 6 focuses the flat-top beam onto the surface of the carrier plate 7 in an imaging manner to remove materials and drill small holes meeting the aperture requirements.

The Gaussian pulse emitted by the pulse laser 3 is incident into the vibrating mirror along the horizontal direction through the diffraction optical device and the laser beam emitted by the beam expanding and collimating mirror, and is vertically incident into the field lens after being converted into the 90-degree direction through the vibrating mirror and the 45-degree reflecting mirror.

The laser drilling system provided by the embodiment of the invention utilizes the shaping system to adjust the waveform of the pulse train sent by the pulse laser and shape the pulse train beam, adjusts the intensity and the phase of the laser beam, and can realize the drilling of different apertures. And by combining the laser method of drilling, the processing flow only needs the steps of beam focusing and cooling blowing, does not need other pretreatment and post-treatment work, and has simple drilling procedure and greatly improved drilling efficiency.

Example 2

The embodiment of the invention also provides a laser drilling method which is applied to the laser drilling system for drilling the carrier plate in the embodiment 1. The laser method comprises the steps of drilling holes by using a pulse laser, forming micropores with the aperture smaller than or equal to 100 microns, particularly with the aperture of 20-70 microns on a carrier plate to be processed by adjusting the waveform of a pulse train sent by the pulse laser and shaping the pulse train beam, wherein the pulse train output frequency of the pulse laser is 1-20kHz, the wavelength is 257-1064nm, and the pulse train comprises at least two parts of sub-pulse waveforms, and the sub-pulse energy in the former part of sub-pulse waveforms is larger than the sub-pulse energy in the latter part of sub-pulse waveforms in sequence.

In a specific embodiment, the pulse train includes two sub-pulse waveforms, where the sub-pulse energy in the former sub-pulse waveform is greater than or equal to 70% of the total pulse train energy, and the sub-pulse energy in the latter sub-pulse waveform is less than 30% of the total pulse train energy.

In a specific embodiment, the pulsed laser is a femtosecond, picosecond or nanosecond laser.

In a specific embodiment, the pulse width of the pulse laser is less than 100ns, preferably 2-20ps, more preferably 5-15ps.

In a specific embodiment, the pulses of the pulse laser are output in the form of pulse trains.

In a specific embodiment, the number of pulses in the pulse train emitted by the pulse laser is greater than 50, preferably 50-300.

In a specific embodiment, the pulse train has a duration of more than 10 μs, for example between 30 and 100 μs.

For example, in one embodiment, reference is made to fig. 2, which is a schematic diagram of carrier drilling using the system of embodiment 1 and the method of embodiment 2. When laser drilling is carried out, the drilling operation is mainly carried out on the electronic material on the carrier plate, the copper-clad plate is not damaged when the electronic material is required to be removed, and meanwhile the drilling taper of the electronic material is ensured.

In this embodiment, the pulse width of the pulse laser is 10ps, the wavelength is 532nm, the frequency of the pulse laser is 5KHz, the number of pulses in the pulse train is 300, and the energy of the single pulse train is 7mj. Referring further to fig. 3, in order to ensure the effect of drilling and improve the material removal efficiency, the present embodiment adjusts the waveform of the pulse train, as shown in fig. 3, and controls the pulse energy of the previous sub-pulse to increase, the pulse energy of the present embodiment to be 12 μj for 60 μs, so as to improve the material removal speed, and then controls the pulse energy of the subsequent sub-pulse to decrease, the pulse energy of the present embodiment to be 6 μj for 40 μs, so as to prevent damage to the underlying copper plate.

The pulse laser of this embodiment can be through the accurate power of control laser of acousto-optic device, can carry out accurate regulation to pulse waveform through software. By adjusting pulse energy and waveform, the laser power density is larger than the damage threshold of the material, and the copper carrier plate at the bottom is not damaged, so that the carrier plate with the aperture of 50 mu m and the thickness of 40 mu m is drilled.

The effect of the carrier plate obtained by drilling according to the processing parameters is shown in fig. 4, and as can be seen from fig. 4, the hole taper obtained by performing laser drilling on the carrier plate in the embodiment of the invention is good, the aperture is between 20 and 70 mu m, the copper-clad plate is complete, and the removal effect of electronic materials is good.

Referring further to Table 1 below, for the specific examples where the system of example 1 and the method of example 2 were used to drill the support, micro-holes of less than or equal to 100 μm were obtained by controlling the laser parameters.

Table 1 laser parameters table for different holes

As is clear from the results in table 1, under the condition of a constant pulse width, wavelength and frequency, by adjusting the waveform of the pulse train emitted from the pulse laser and shaping the pulse train beam, the output pulse train is adjusted to include at least two sub-pulse waveforms, and the sub-pulse energy in the former sub-pulse waveform and the sub-pulse energy in the latter sub-pulse waveform are adjusted, so that high-quality micropores with apertures of 10 to 100 μm, particularly 20 μm to 70 μm, can be obtained.

It will be appreciated that in other embodiments, the thicker the electronic material on the carrier plate, the greater the energy required for laser drilling and the longer the time required to effectively ensure adequate removal of the material, as well as the taper of the drill.

According to the laser drilling method provided by the embodiment of the invention, the ultrafast pulse, the adjustable pulse waveform and the beam shaping are adopted, and more sub-pulses are adopted to remove materials, so that the micro-holes with the aperture of 10-100 mu m, especially the micro-holes with the aperture of 20-70 mu m, are obtained. The laser drilling method has the advantages of no heat affected zone, difficult layering of materials, no problems of molten materials, volcanic vent, residual glue at the bottom of the hole, protruding glass fiber and the like, clean bottom of the hole, hole washing effect, no need of pretreatment and the like. The action mechanism of the whole laser and the material is mainly cold processing removal, so that the influence caused by the heat effect is greatly reduced, and the taper of the drilling hole and the smoothness of the bottom surface are ensured.

The laser drilling method provided by the embodiment of the invention can be used for manufacturing a circuit board, the carrier plate can be directly used for laser drilling in a drilling process without the treatment of film pasting, windowing and the like, and the laser waveform can be adjusted according to the condition of a processed material in the laser processing process by adding the diffraction optical device in the laser drilling system, so that the material removing efficiency and the drilling efficiency are improved.

In the foregoing embodiments, the descriptions of the embodiments are focused on, and for those portions of one embodiment that are not described in detail, reference may be made to the related descriptions of other embodiments.

While the invention has been described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes and substitutions of equivalents may be made and equivalents will be apparent to those skilled in the art without departing from the scope of the invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims (10)

1. A laser drilling method is characterized in that a pulse laser is used for drilling, a pulse train emitted by the pulse laser is regulated to form micro holes with the aperture of 10-100 mu m on a material to be processed, and the pulse train comprises at least two parts of sub-pulse waveforms, wherein the sub-pulse energy in the former part of sub-pulse waveforms is larger than the sub-pulse energy in the latter part of sub-pulse waveforms according to the sequence.

2. The laser drilling method of claim 1, wherein the pulse laser has a pulse train output frequency of 1-20kHz and a wavelength of 257-1064nm.

3. The laser drilling method of claim 1, wherein the pulse train comprises two sub-pulse waveforms, the sub-pulse energy in the former sub-pulse waveform being greater than or equal to 70% of the total pulse train energy, and the sub-pulse energy in the latter sub-pulse waveform being less than 30% of the total pulse train energy.

4. The laser drilling method of claim 1, wherein the pulsed laser is a femtosecond, picosecond, or nanosecond laser.

5. The laser drilling method of claim 1, wherein the pulse width of the pulsed laser is less than 100ns.

6. The laser drilling method of claim 1, wherein the pulse laser emits a pulse train with a number of pulses greater than 50.

7. The laser drilling method of claim 6, wherein the pulse train is longer than 10 μs.

8. A laser drilling system for performing the laser drilling method of any one of claims 1-7.

9. The laser drilling system of claim 8, comprising a pulsed laser, a shaping system, a galvanometer system, a focusing system, a motion control system, a quality monitoring system, a software system, and an auxiliary blowing module, wherein the gaussian pulse emitted by the pulsed laser is incident into the focusing system through the shaping system and the galvanometer system, the laser is emitted from the focusing system to be focused on the surface of the material to be processed, the shaping system is used for shaping the beam, the motion control system controls the motion of the material to be processed on the processing plane, the auxiliary blowing module is used for cooling and blowing the surface of the processed material, the quality monitoring system is used for monitoring the quality of the drilled hole in the processing process, and the software system is used for controlling the process pretreatment and the drilling process.

10. The laser drilling system of claim 9, wherein the shaping system comprises a diffractive optic to convert a gaussian beam emitted by the pulsed laser into a flat top beam or a flat top-like beam, the diffractive optic including, but not limited to, a DOE, a phase plate, an aperture stop, a microlens array, an aspheric lens.