WO2022222411A1

WO2022222411A1 - Pcb short-wavelength pulse laser drilling method and related apparatus

Info

Publication number: WO2022222411A1
Application number: PCT/CN2021/127584
Authority: WO
Inventors: 王成勇; 黄欣; 严冰; 陶雯雯; 郑李娟
Original assignee: 广东工业大学
Priority date: 2021-04-22
Filing date: 2021-10-29
Publication date: 2022-10-27
Also published as: CN113210856A; WO2022222429A1; CN113210856B

Abstract

A PCB short-wavelength pulse laser drilling method. The method comprises: extracting PCB data, the PCB data comprising: a PCB thickness, a hole depth of a hole to be drilled, a hole center position of said hole, and a hole diameter of said hole; comparing the hole depth of said hole with the PCB thickness, and determining the type of said hole; if a comparison result is that the hole depth of said hole is equal to the PCB thickness, determining that said hole is a through hole, and using an annular light beam to perform jacking through-hole drilling on a PCB at the hole center position of said hole; and if the comparison result is that the hole depth of said hole is less than the thickness of the PCB, determining that said hole is a blind hole, and respectively using a Gaussian light beam and an annular light beam to perform step blind-hole drilling on the PCB at the same hole center position of said hole. The drilling method can simultaneously implement through hole machining and blind hole machining of a multi-layer flexible board and a multi-layer rigid board on one device, so that the problems in the prior art that the taper is large, a glue remains at the bottom, heat accumulation is serious, the machining efficiency is low and the like during the process of laser drilling are solved.

Description

PCB short-wavelength pulsed laser drilling method and related drilling device

technical field

The present application relates to the technical field of PCB laser drilling, and in particular, to a PCB short-wavelength pulsed laser drilling method and a related drilling device.

Background technique

Electronic products continue to improve the performance of the whole machine in design, and pursue the miniaturization of Printed Circuit Board (PCB); therefore, it is necessary to micro-drill the through holes or blind holes of the PCB, and perform metallization, thereby Realize the conduction and signal transmission of internal lines, improve performance and miniaturize the PCB.

At present, the drilling of micro-via holes and micro-blind holes on PCBs is mainly processed by ultraviolet (UV) laser or CO2 laser; among them, UV laser is mainly used for processing blind holes and a small number of through holes, and the depth of the holes processed by UV laser is deep. The diameter ratio (the ratio of hole depth to diameter) is limited, and at the same time, limited by the laser power, its drilling speed is slow and can only be used to process flexible printed boards or rigid printed boards with a small thickness; while CO2 lasers are mainly used for processing Rigid printed board, and since the copper foil on the surface of the printed board has a very low absorption rate, the surface of the printed board must be browned or blackened before processing, or a window treatment should be carried out at the position to be processed to remove it in advance The copper foil on the surface, and then use CO2 laser ablation to remove the inner layer insulating material.

Therefore, for the processing of flexible boards and rigid boards, it is necessary to use UV laser drilling machines and CO2 laser drilling machines respectively, and it is impossible to realize through-hole and blind-hole processing of multi-layer flexible boards and multi-layer rigid boards on one device. In addition, for through-hole processing, UV laser drilling machine needs to ablate all the materials in the hole to form through-holes, which has low processing efficiency and serious heat accumulation, and it is difficult to process multi-layer PCBs containing glass fibers. However, CO2 laser processing has problems such as large hole taper and residual glue at the bottom of blind hole processing, and the process is complicated and produces a large amount of chemical waste water.

SUMMARY OF THE INVENTION

In order to overcome the problems existing in the related art, the present application provides a PCB short-wavelength pulsed laser drilling method, which can simultaneously realize through holes and blind holes of a multilayer flexible board and a multilayer rigid board on one device. It solves the problems of large hole taper, bottom glue residue, serious heat accumulation and low processing efficiency in the laser drilling process in the prior art.

A first aspect of the present application provides a PCB short-wavelength pulsed laser drilling method, comprising:

Step 1: extracting PCB data, the PCB data includes: PCB thickness, hole depth to be drilled, hole center position to be drilled, and hole diameter to be drilled;

Step 2: Compare the depth of the hole to be drilled and the thickness of the PCB to determine the type of the hole to be drilled;

Step 3: The comparison result in Step 2 is that the depth of the hole to be drilled is equal to the thickness of the PCB, then it is determined that the hole to be drilled is a through hole, and a ring beam is used to cover the center of the hole to be drilled on the PCB. Through holes are drilled, and the spot diameter of the annular beam irradiated on the PCB is equal to the aperture to be drilled;

Step 4: The comparison result in step 2 is that the depth of the hole to be drilled is less than the thickness of the PCB, then it is determined that the hole to be drilled is a blind hole, and the Gaussian beam and the annular beam are used to drill the same hole on the PCB respectively. Blind holes are drilled in sections at the center position, and the diameter of the spot of the Gaussian beam irradiated on the PCB is smaller than the aperture to be drilled, and the diameter of the spot of the annular beam irradiated on the PCB is equal to the aperture to be drilled.

In one embodiment, in step 4, the use of Gaussian beams and annular beams to drill blind holes in sections on the PCB for the same hole center position to be drilled includes:

Use a Gaussian beam to perform preliminary drilling at the center of the hole to be drilled on the PCB, and the drilling depth of the preliminary drilling is less than or equal to the depth of the hole to be drilled to obtain a conical pre-drilled hole; use a ring beam to drill all the holes. The conical pre-drilling hole is used for secondary drilling, and the drilling depth of the secondary drilling hole is equal to the depth of the hole to be drilled, and the hole wall is trimmed.

Use a ring beam to perform preliminary drilling at the center of the hole to be drilled on the PCB, and the drilling depth of the initial drill is equal to the depth of the hole to be drilled to obtain an annular pre-drilled hole; use a Gaussian beam to drill the annular pre-drilled hole The hole is drilled for a second time, and the drilling depth of the second drilling is equal to the depth of the hole to be drilled, and the residue in the hole is eliminated.

In one embodiment, when drilling with a Gaussian beam or a ring beam,

The diameter of the spot irradiated on the PCB by the Gaussian beam or the annular beam is smaller than the aperture to be drilled, and the drilling path of the Gaussian beam or the annular beam is a circular drilling or a spiral drilling.

A second aspect of the application provides a PCB short-wavelength pulsed laser drilling device, adapted to the above-mentioned PCB short-wavelength pulsed laser drilling method, comprising:

A base and a mobile platform, a laser source, a beam splitter, a Gaussian optical path module and a ring optical path module mounted on the base;

The laser beam emitted by the laser source is divided into a first sub-beam and a second sub-beam by the beam splitter, wherein the first sub-beam is processed by the Gaussian optical path module to emit a Gaussian beam, and the second sub-beam After being processed by the ring light path module, a ring beam is emitted;

The beams emitted by the Gaussian optical path module and the annular optical path module are both irradiated on the mobile platform, and the mobile platform can move horizontally relative to the Gaussian optical path module and the annular optical path module, so that the Gaussian optical path module can move horizontally. The light beams generated by the module and the annular light path module can be successively irradiated on the same point on the moving platform.

In one embodiment, the Gaussian optical path module includes: a first mirror group, a first scanning galvanometer and a first focusing mirror;

The first sub-beam emitted by the beam splitter is sequentially optically processed by the first reflection mirror group, the first scanning galvanometer and the first focusing mirror, and the first reflection mirror group The first partial beam reflects and adjusts the incident angle, so that the first partial beam is vertically irradiated on the moving platform, the scanning galvanometer is used to control the deflection of the first partial beam, and the focusing mirror is used to adjust the The focal position of the first partial beam.

In one embodiment, the annular optical path module includes: a second mirror group, a second scanning galvanometer, a second focusing mirror, and an axicon;

The axicon is installed between the beam splitter and the second reflection mirror group, and shapes the second partial beam emitted by the beam splitter to obtain a ring beam.

In one embodiment, the laser source comprises: a short wavelength pulsed laser and a beam expander;

The short-wavelength pulsed laser generates a laser beam, and the beam expander is installed between the short-wavelength pulsed laser and the beam splitter, and the laser beam is subjected to beam area increase processing and collimation processing; the short-wavelength pulsed laser The beam quality M2 factor of the laser is less than 1.3, its wavelength is in the ultraviolet band between 248 and 355nm and the green band between 532 and 515nm, and its pulse repetition frequency is greater than or equal to 90kHz.

In one embodiment, the Gaussian optical path module and the annular optical path module are both mounted on the base through a lifting mechanism, and the lifting mechanism is composed of a Z-axis slide rail vertically fixed to the base and a slider driven by a motor ;

Both the Gaussian optical path module and the annular optical path module are fixedly mounted on the slider and move vertically along the Z-axis slide rail with the slider;

The PCB short-wavelength pulse laser drilling device further includes a control module, which is respectively connected in communication with the laser source, the Gaussian optical path module, the annular optical path module, the mobile platform and the lifting mechanism;

The control module controls the laser source to start or close by sending instructions to the laser source, the Gaussian light path module, the ring light path module and the lifting mechanism, and the Gaussian light path module and the ring light path module emit light. The parameters of the laser; the control module controls the horizontal movement of the PCB carrying the mobile platform by sending instructions to the mobile platform.

In one embodiment, the Gaussian optical path module further comprises: a beam shaper;

The beam shaper is arranged between the beam splitter and the first reflecting mirror group, and the beam shaper is used for shaping the Gaussian beam into a flat-top beam.

The technical solution provided by this application can include the following beneficial effects:

In this embodiment of the present application, the PCB drilling requirements (ie, drilling through holes or blind holes) can be identified through the PCB data, and a switching drilling mode that matches the drilling requirements can be selected to realize the At the same time, the need for through-hole processing and blind-hole processing of the circuit board; when the through-hole needs to be drilled, the annular beam is used for nesting processing, which can concentrate the removal of the material around the hole, and the material inside the hole is separated from the hole wall after the through-hole is formed. And automatic drop, compared with the traditional Gaussian laser processing, does not need to ablate all the material inside the hole, which can reduce the amount of material removal and improve the processing efficiency. When blind holes need to be drilled, Gaussian beam and annular beam are used for combined processing, which can effectively reduce the thermal influence of traditional Gaussian laser processing, further trim the quality of the hole wall, remove residual glue at the bottom, improve drilling efficiency, and optimize drilling. hole effect.

Description of drawings

The above and other objects, features and advantages of the present application will become more apparent from the more detailed description of the exemplary embodiments of the present application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the exemplary embodiments of the present application. same parts.

1 is a schematic flowchart of a PCB short-wavelength pulsed laser drilling method shown in an embodiment of the present application;

Fig. 2 is another schematic flow chart of the PCB short-wavelength pulsed laser drilling method shown in the embodiment of the present application;

FIG. 3 is a schematic structural diagram of a PCB short-wavelength pulsed laser drilling device shown in an embodiment of the present application.

Detailed ways

Preferred embodiments of the present application will be described in more detail below with reference to the accompanying drawings. While preferred embodiments of the present application are shown in the drawings, it should be understood that the present application may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the scope of this application to those skilled in the art.

The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this application and the appended claims, the singular forms "a," "the," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It will also be understood that the term "and/or" as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, such information should not be limited by these terms. These terms are only used to distinguish the same type of information from each other. For example, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information without departing from the scope of the present application. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. In the description of the present application, "plurality" means two or more, unless otherwise expressly and specifically defined.

In the existing field of PCB manufacturing, flexible printed circuit board refers to a highly reliable and excellent flexible printed circuit board made of polyimide or polyester film; rigid printed circuit board Board refers to printed circuit boards with phenolic paper laminates, epoxy paper laminates, polyester glass felt laminates or epoxy glass cloth laminates.

At present, the drilling of micro-through holes and micro-blind holes on PCBs mainly uses ultraviolet lasers or CO2 lasers (CO2 lasers refer to carbon dioxide lasers, the wavelength of the laser emitted is 10.6 microns, and the "body" is in the infrared region, which is invisible to the naked eye. Among them, there are two working modes: continuous and pulsed) processing; among them, ultraviolet laser can be directly used to process blind holes and through holes, but the depth to diameter ratio of holes processed by ultraviolet laser is relatively limited, and is limited by laser power, making drilling The hole speed is slow and can only be used to process flexible printed boards or rigid printed boards with a small thickness. Especially for the glass fiber in the PCB dielectric layer, it can only be removed by increasing the energy density to a high degree; and CO2 laser due to The copper foil on the surface of the printed board has a very low absorption rate. Before processing, the surface of the printed board must be browned or blackened, or a window treatment should be performed at the position to be processed, and the copper foil on the surface should be removed in advance and reused. CO2 laser ablation removes the inner layer insulating material; the above two processing methods are relatively complicated, and chemical treatment is required when using CO2 laser, which is easy to cause chemical pollution, and problems such as large hole taper and bottom glue residue are very likely to occur during processing .

In view of the above problems, an embodiment of the present application provides a method for drilling a PCB with a short-wavelength pulsed laser. By drilling a PCB with a short-wavelength pulsed laser, the hole taper (the taper refers to the difference between the diameters of the upper and lower holes of the cone and the height of the cone) can be obtained. PCB holes with small differences and small residual glue at the bottom; and this laser drilling method does not require browning or blackening of the PCB surface before laser drilling, nor does it need to open windows at the position to be processed It reduces the chemical pretreatment steps of PCB laser drilling and improves the drilling efficiency. The technical solutions of the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

Example 1

FIG. 1 is a schematic flowchart of a PCB short-wavelength pulsed laser drilling method shown in an embodiment of the present application. Referring to FIG. 1 , the technical solution provided by the present application is an embodiment of a method for short-wavelength pulsed laser drilling of a PCB, including:

101. Extract PCB data, the PCB data includes: PCB thickness, hole depth to be drilled, hole center position to be drilled, and hole diameter to be drilled;

In this embodiment, it is necessary to process through holes or blind holes on the PCB and perform metallization to realize the conduction and signal transmission functions of the internal circuits.

Among them, the hole depth to be drilled refers to the hole depth required by PCB laser drilling;

Among them, the hole center position to be drilled refers to the hole center position of the hole required by PCB laser drilling (for example, the coordinate signal or size information on the PCB surface);

Among them, the hole diameter to be drilled refers to the hole diameter required by PCB laser drilling;

Among them, the PCB thickness refers to the board thickness of the PCB.

102. Compare the depth of the hole to be drilled and the thickness of the PCB to determine the type of the hole to be drilled;

If the comparison result is that the depth of the hole to be drilled is equal to the thickness of the PCB, it is determined that the hole to be drilled is a through hole.

If the comparison result is that the depth of the hole to be drilled is smaller than the thickness of the PCB, it is determined that the hole to be drilled is a blind hole.

103. If the depth of the hole to be drilled is equal to the thickness of the PCB, it is determined that the to-be-drilled hole is a through hole, and a ring beam is used to drill the through hole at the center of the hole to be drilled on the PCB;

If the comparison result in step 102 is that the depth of the hole to be drilled is equal to the thickness of the PCB, it is determined that the hole to be drilled is a through hole, and a ring beam is used to drill the through hole at the center of the hole to be drilled on the PCB. , and the diameter of the spot of the annular beam irradiated on the PCB is equal to the aperture to be drilled. Exemplarily, assuming that the aperture to be drilled is 50 μm, the irradiation diameter of the annular beam is directly set to 50 μm.

Among them, nesting processing means that for a solid solid, to process through holes (holes that penetrate up and down), it is only necessary to remove the material on the circumference of the hole, and separate the material in the central part from the hole wall to form a through hole, and There is no need to remove all material from the center. The main function is to carry out hole processing. For the case where the aperture is equal to the diameter of the annular beam, only the through-hole processing can be realized by using the nested pulse laser processing. The material removal amount is smaller than that of the traditional pulse processing, which can effectively improve the processing efficiency.

The annular beam emitted by the PCB short-wavelength pulsed laser drilling device is used for pulse processing, and the through hole is processed by the nesting method. Since the energy of the annular beam is concentrated in the circumference, the material at the circumference of the hole can be removed by concentrated ablation to form a hole after the through hole. The inner material separates from the hole wall and falls automatically.

104. If the depth of the hole to be drilled is less than the thickness of the PCB, determine that the hole to be drilled is a blind hole, and use Gaussian beam and annular beam respectively to perform segmented blind drilling on the same hole center position to be drilled on the PCB. hole.

If the comparison result in step 102 is that the depth of the hole to be drilled is less than the thickness of the PCB, then it is determined that the hole to be drilled is a blind hole, and the Gaussian beam and the annular beam are used to drill the same hole center on the PCB. Blind holes are drilled in sections, and the spot diameter of the Gaussian beam irradiated on the PCB is smaller than the aperture to be drilled, and the spot diameter of the annular beam irradiated on the PCB is equal to the aperture to be drilled.

Among them, the Gaussian beam is the laser light speed or electron beam whose amplitude distribution of the cross-section of the fundamental mode radiation field follows a Gaussian function. Further, the Gaussian beam can be shaped by a beam shaper into a top-hat beam, which is a laser beam or electron beam with an almost uniform flux (energy density) in a circular area. In practical applications, the flat-top beam can achieve uniform distribution of laser energy, which helps to improve processing accuracy.

In the embodiments of the present application, the short-wavelength pulsed laser refers to a type of laser, which is mainly in the ultraviolet band (248nm-355nm) and visible light band compared to the long-wavelength laser (near-infrared and mid-infrared bands). (515nm ~ 532nm) laser, that is, laser with short wavelength.

When the above-mentioned Gaussian beam or annular beam is used for drilling, if the diameter of the spot irradiated on the PCB by the Gaussian beam or the annular beam is smaller than the aperture to be drilled, then a surrounding drilling or a spiral drilling is used. Specifically, the spiral drilling refers to a drilling method in which the light beam starts from the position of the hole center, and performs a spiral path scanning within the aperture range to be drilled to remove the material in the PCB hole to obtain the PCB hole; the Encircling drilling refers to the method in which the beam takes the hole center position as the center of the circle and scans the drilling circle by circle according to the concentric ring paths of different diameters to obtain the PCB hole.

For PCB laser processing, the shorter the laser wavelength of drilling, the higher the absorption rate of the material to the laser. Since the PCB composition materials generally include copper foil, glass fiber and epoxy resin, the above materials are all good for short-wavelength lasers. Therefore, the short-wavelength pulsed laser can be used to directly process the PCB, which can achieve the purpose of ablation and removal of materials; while the CO2 laser with a longer wavelength has a very low absorptivity of the copper foil (often lower than 1%). Therefore, it is not possible to use CO2 laser for direct processing. It is necessary to blacken or brown the copper foil on the surface of the sheet to improve the surface absorption rate before processing the PCB with CO2 laser.

Embodiment 2

In step 104 of the above-mentioned embodiment 1, the scheme of "using Gaussian beam and annular beam to drill blind holes in segments on the same hole center position to be drilled on the PCB" is described. This scheme has the following two options: implementation, including:

(1) 201a, use a Gaussian beam to perform preliminary drilling at the position of the hole center to be drilled on the PCB, and the drilling depth of the preliminary drilling is less than or equal to the depth of the hole to be drilled to obtain a conical pre-drilled hole ( rough pore walls);

202a. Use an annular beam to perform secondary drilling on the conical pre-drilled hole, the drilling depth of the secondary drilling hole is equal to the depth of the hole to be drilled, and the hole wall is trimmed.

It is worth noting that in the filling process, as the depth of processing increases, the plasma formed by laser ablation tends to gather above the plate, thereby blocking the laser ablation of the material in the hole, resulting in a larger hole taper (that is, the diameter of the bottom of the blind hole is much smaller than the diameter of the entrance, and the entire hole cross-section is tapered), so this application proposes to first use a Gaussian beam into the system for filling processing to remove the material inside the blind hole, and then use a ring beam to carry out the tapered hole. Trim, reduce taper of hole, remove glue residue at bottom of blind hole.

(2) 201b, use the annular beam to perform preliminary drilling at the position of the hole center to be drilled on the PCB, and the drilling depth of the preliminary drilling is equal to the depth of the hole to be drilled to obtain an annular pre-drilled hole (hole wall). There is residual swarf in the flat center);

202b. Perform secondary drilling on the annular pre-drilled hole by using a Gaussian beam, the drilling depth of the secondary drilling hole is equal to the depth of the hole to be drilled, and the residue in the hole is eliminated.

In the process of repeatedly processing a hole at the same position with Gaussian laser multi-pulse, it is very easy to damage the material around the circumference of the hole due to heat accumulation, forming a heat-affected zone. The present application proposes to use a ring beam for initial drilling to isolate the material inside the hole from the peripheral material around the hole, and then use a Gaussian beam for secondary drilling to remove the residual material in the hole without damaging the material around the hole and reducing thermal effects. Area.

Embodiment 3

The embodiment of the present application also provides a PCB short-wavelength pulsed laser drilling device for realizing the above-mentioned PCB short-wavelength pulsed laser drilling method, please refer to FIG. 3, an embodiment of the PCB short-wavelength pulsed laser drilling device includes:

The base 60 and the mobile platform 70 installed on the base, the laser source (including the short-wavelength pulse laser 10 and the beam expander 20), the beam splitter 30, the Gaussian optical path module (including: the first scanning galvanometer B1, the first reflection mirror The mirror group (including the mirror A1 and the mirror A2) and the first focusing mirror C1) and the annular optical path module (including: the second mirror group (including the mirror A3 and the mirror A4), the second scanning mirror B2 and the first Two focusing mirrors C2);

The beams emitted by the Gaussian optical path module and the annular optical path module are both irradiated on the moving platform 70, and the moving platform 70 can move horizontally relative to the Gaussian optical path module and the annular optical path module, so that the The beams generated by the Gaussian optical path module and the annular optical path module can be successively irradiated on the same point on the moving platform.

The laser source includes: a short-wavelength pulsed laser 10 and a beam expander 20;

The short-wavelength pulsed laser 10 generates a laser beam, and the beam expander 20 is installed between the short-wavelength pulsed laser 10 and the beam splitter 30, and the laser beam is subjected to beam area increase processing and collimation processing; The beam quality M2 factor of the short-wavelength pulsed laser is less than 1.3, and its wavelength is in the ultraviolet band between 248 and 355nm and in the green band between 532 and 515nm, and its pulse repetition frequency is greater than or equal to 90kHz. The beam expander 20 is used to receive the laser beam and perform beam area increase processing.

The Gaussian optical path module includes: a first reflecting mirror group (including reflecting mirror A1 and reflecting mirror A2), a first scanning galvanometer B1 and a first focusing mirror C1;

The reflector A1 in the first reflector group adjusts the beam propagation path, so that the beam and the center of the beam splitter 30 are kept on the same axis, and the beam enters from the center of the beam splitter 30; the first split beams emitted by the beam splitter 30 are sequentially After the optical processing of the reflecting mirror A2, the first scanning galvanometer B1 and the first focusing mirror C1 in the first reflecting mirror group, the first partial beam is vertically irradiated on the moving platform 70, The first scanning galvanometer B1 is used to control the deflection of the first partial beam, and the first focusing mirror C1 is used to adjust the focus position of the first partial beam.

The annular optical path module includes: a second mirror group, a second scanning galvanometer B2, a second focusing mirror C2 and an axicon 40;

The axicon 40 is installed between the beam splitter 30 and the reflecting mirror A3, and shapes the second split beam emitted by the beam splitter to obtain a ring beam.

Specifically, the diffractive axicon used in this application is an evolutionary version of the traditional axicon, and the divergence angle of the diffractive axicon can also be calculated from the traditional axicon that can output the same properties, that is, the characteristic parameters of the traditional axicon can be The diffractive axicon is introduced to produce the same effect, and the difference between the two is that the diffractive axicon has better accuracy, a larger parameter range, can eliminate the central dead zone, and the diffractive axicon is more refined and can form a structure More compact and finer optical modules.

The specific flow of the above-mentioned PCB short-wavelength pulsed laser drilling method by the PCB short-wavelength pulsed laser drilling device is described below:

The control module (eg, programmable logic controller PLC or CPU) extracts PCB data, the PCB data includes: PCB thickness, hole depth to be drilled, center position of the hole to be drilled, and hole diameter to be drilled.

The control module compares the depth of the hole to be drilled and the thickness of the PCB, and determines the type of the hole to be drilled. If the comparison result is that the depth of the hole to be drilled is equal to the thickness of the PCB, it is determined that the hole to be drilled is through hole; if the comparison result is that the depth of the hole to be drilled is less than the thickness of the PCB, it is determined that the to-be-drilled hole is a blind hole.

The short-wavelength pulsed laser 10 sends the laser beam through the beam expander 20 , the reflection mirror A1 and the beam splitter 30 to generate the first partial beam and the second partial beam.

The first sub-beam enters the Gaussian optical path module for optical processing, specifically: the first sub-beam is irradiated into the first scanning galvanometer B1 through the reflecting mirror A2, and the first scanning galvanometer B1 controls the deflection of the first sub-beam, It is then irradiated into the first focusing mirror C1, and the focus position of the first partial beam is adjusted so that the first partial beam can be irradiated to the PCB placed on the mobile platform 70, and the Gaussian beam is controlled by the deflection of the first scanning galvanometer B1. Spiral drilling or wrap-around drilling on PCBs. Optionally, if the Gaussian beam needs to be further processed into a flat-top beam, a beam shaper is also provided between the beam splitter 30 and the reflecting mirror A2, and the first split beam can be processed by the Gaussian beam through the beam shaper. into a flat-top beam.

The second sub-beam enters the annular optical path module for optical processing, specifically: the second sub-beam is shaped into an annular beam by the axicon 40, and then irradiated to the second scanning galvanometer B2 through the reflecting mirror A3 and the reflecting mirror A4. The second scanning galvanometer B2 controls the deflection of the second sub-beam, and then irradiates it to the second focusing mirror C2 to adjust the focus position of the second sub-beam, so that the second sub-beam can be irradiated on the moving platform 70. PCB, through the deflection of the second scanning galvanometer B2 to control the annular beam to perform spiral drilling or wrap-around drilling on the PCB.

Exemplarily, if the control module identifies that the depth of the hole to be drilled in the current PCB is equal to the thickness of the PCB, it is determined that the to-be-drilled hole is a through hole. The control module controls the second sub-beam to perform nesting drilling through holes on the PCB.

Exemplarily, if the control module identifies that the depth of the hole to be drilled in the current PCB is smaller than the thickness of the PCB, it is determined that the hole to be drilled is a blind hole. The control module controls the first sub-beam and the second sub-beam to drill blind holes in sections on the PCB respectively.

Embodiment 4

In practical applications, the Gaussian optical path module and the annular optical path module also need to move in the vertical direction. The embodiments of the present application provide corresponding design solutions, specifically:

Based on the PCB short-wavelength pulsed laser drilling device of the third embodiment, the Gaussian optical path module and the annular optical path module are both mounted on the base 60 through a lifting mechanism, and the lifting mechanism is vertically fixed on the Z-axis of the base. The slide rail 50 is composed of a slider driven by a motor.

Please refer to FIG. 3, the Gaussian optical path module and the annular optical path module in the figure are respectively connected with the Z-axis slide rail 50, one end of the Z-axis slide rail 50 is fixed to the base 60, and the other end is fixed to the Gaussian optical path module or the annular optical path module, The Gaussian optical path module or the annular optical path module can be moved in the vertical direction through the Z-axis slide rail 50 .

In the embodiment of the present application, a new lifting mechanism (composed of the Z-axis slide rail 50 vertically fixed to the base and a motor-driven slider) is added, so that the PCB short-wavelength pulse laser drilling device in the present application can cooperate with The above-mentioned moving platform 70 controls the Gaussian optical path module and the annular optical path module to move in the directions of the X-axis, Y-axis and Z-axis respectively relative to the PCB to be drilled, so as to realize precise position control.

Embodiment 5

Based on the PCB short-wavelength pulsed laser drilling device in the third or fourth embodiment, the PCB short-wavelength pulsed laser drilling device in the embodiment of the present application further includes a control module, the control module is respectively connected with the laser source, the Gaussian The optical path module, the annular optical path module, the mobile platform and the lifting mechanism are connected in communication.

The control module controls the laser source to start or close by sending instructions to the laser source, the Gaussian light path module, the ring light path module and the lifting mechanism, and the laser light emitted by the Gaussian light path module and the ring light path module. parameters; the control module controls the horizontal movement of the PCB carrying the mobile platform by sending an instruction to the mobile platform.

Specifically, the control module controls each module in the PCB short-wavelength pulsed laser drilling device to execute the specific process of the above-mentioned PCB short-wavelength pulsed laser drilling method, reference may be made to the third embodiment, which will not be repeated here.

In practical applications, when laser drilling a PCB, the control of the laser beam energy emitted by the laser is often uneven, resulting in damage to the PCB during the drilling process and increasing the error rate of production products. During the drilling process, the beam quality M2 factor of the short-wavelength pulsed laser can be adjusted to be less than 1.3 through the control module, and the repetition frequency of the beam is generally set to be greater than or equal to 90kHz to ensure that there is enough laser energy during processing to remove the specified location material.

In the PCB short-wavelength pulsed laser drilling device in the embodiment of the present application, the PCB drilling requirements (ie, drilling through holes or blind holes) can be identified through the PCB data, and a switching drilling mode that matches the drilling requirements can be selected. , to achieve the requirements of through-hole processing and blind-hole processing of the circuit board at the same time on one device; when drilling through-holes is required, the annular beam is used for nesting processing, which can concentrate the removal of the material around the hole and form through-holes The material inside the rear hole is separated from the hole wall and automatically falls off. Compared with traditional Gaussian laser processing, there is no need to ablate all the material inside the hole, which can reduce the amount of material removal and improve the processing efficiency. When blind holes need to be drilled, Gaussian beam and annular beam are used for combined processing, which can effectively reduce the thermal influence of traditional Gaussian laser processing, further trim the quality of the hole wall, remove residual glue at the bottom, improve drilling efficiency, and optimize drilling. hole effect.

The solution of the present application has been described in detail above with reference to the accompanying drawings. In the above-mentioned embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments. Those skilled in the art should also know that the actions and modules involved in the description are not necessarily required by the present application. In addition, it can be understood that the steps in the method of the embodiment of the present application may be sequentially adjusted, combined and deleted according to actual needs, and the modules in the device of the embodiment of the present application may be combined, divided and deleted according to actual needs.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems and methods according to various embodiments of the present application. It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It is also noted that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented in dedicated hardware-based systems that perform the specified functions or operations , or can be implemented in a combination of dedicated hardware and computer instructions.

Various embodiments of the present application have been described above, and the foregoing descriptions are exemplary, not exhaustive, and not limiting of the disclosed embodiments. Numerous modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the various embodiments, the practical application or improvement over the technology in the marketplace, or to enable others of ordinary skill in the art to understand the various embodiments disclosed herein.

Claims

A PCB short-wavelength pulsed laser drilling method, comprising the following steps:

Step 1: extracting PCB data, the PCB data includes: PCB thickness, hole depth to be drilled, hole center position to be drilled, and hole diameter to be drilled;

Step 2: Compare the depth of the hole to be drilled and the thickness of the PCB to determine the type of the hole to be drilled;

Step 3: The comparison result in Step 2 is that the depth of the hole to be drilled is equal to the thickness of the PCB, then it is determined that the hole to be drilled is a through hole, and a ring beam is used to cover the center of the hole to be drilled on the PCB. Through holes are drilled, and the spot diameter of the annular beam irradiated on the PCB is equal to the aperture to be drilled;

Step 4: The comparison result in Step 2 is that the depth of the hole to be drilled is less than the thickness of the PCB, then the to-be-drilled hole is determined to be a blind hole, and the same to-be-drilled hole is drilled on the PCB using the Gaussian beam and the annular beam respectively. Blind holes are drilled in sections at the center of the hole, and the spot diameter of the Gaussian beam irradiated on the PCB is smaller than the aperture to be drilled, and the spot diameter of the annular beam irradiated on the PCB is equal to the aperture to be drilled.
The PCB short-wavelength pulsed laser drilling method according to claim 1, wherein:

In step 4, the Gaussian beam and the annular beam are respectively used to drill the blind hole segmentally on the PCB for the same hole center position to be drilled, including:

Use a Gaussian beam to perform preliminary drilling at the center of the hole to be drilled on the PCB, and the drilling depth of the preliminary drilling is less than or equal to the depth of the hole to be drilled to obtain a conical pre-drilled hole; use a ring beam to drill all the holes. The conical pre-drilling hole is used for secondary drilling, and the drilling depth of the secondary drilling hole is equal to the depth of the hole to be drilled, and the hole wall is trimmed.
The PCB short-wavelength pulsed laser drilling method according to claim 1, wherein:

In step 4, the Gaussian beam and the annular beam are respectively used to drill the blind hole segmentally on the PCB for the same hole center position to be drilled, including:

Use a ring beam to perform preliminary drilling at the center of the hole to be drilled on the PCB, and the drilling depth of the initial drill is equal to the depth of the hole to be drilled to obtain an annular pre-drilled hole; use a Gaussian beam to drill the annular pre-drilled hole The hole is drilled for a second time, and the drilling depth of the second drilling is equal to the depth of the hole to be drilled, and the residue in the hole is eliminated.
The PCB short-wavelength pulsed laser drilling method according to claim 1, characterized in that: when using a Gaussian beam or an annular beam for drilling,

The diameter of the spot irradiated on the PCB by the Gaussian beam or the annular beam is smaller than the aperture to be drilled, and the drilling path of the Gaussian beam or the annular beam is a circular drilling or a spiral drilling.
A PCB short-wavelength pulsed laser drilling device, adapted to the PCB short-wavelength pulsed laser drilling method according to any one of claims 1-4, characterized in that:

Including a base and a mobile platform mounted on the base, a laser source, a beam splitter, a Gaussian optical path module and a ring optical path module;

The laser beam emitted by the laser source is divided into a first sub-beam and a second sub-beam by the beam splitter, wherein the first sub-beam is processed by the Gaussian optical path module to emit a Gaussian beam, and the second sub-beam After being processed by the ring light path module, a ring beam is emitted;

The beams emitted by the Gaussian optical path module and the annular optical path module are both irradiated on the mobile platform, and the mobile platform can move horizontally relative to the Gaussian optical path module and the annular optical path module, so that the Gaussian optical path module can move horizontally. The light beams generated by the module and the annular light path module can be successively irradiated on the same point on the moving platform.
The PCB short-wavelength pulsed laser drilling device according to claim 5, wherein:

The Gaussian optical path module includes: a first mirror group, a first scanning galvanometer and a first focusing mirror;

The first sub-beam emitted by the beam splitter is sequentially optically processed by the first reflection mirror group, the first scanning galvanometer and the first focusing mirror, and the first reflection mirror group The first partial beam reflects and adjusts the incident angle, so that the first partial beam is vertically irradiated on the moving platform, the first scanning galvanometer is used to control the deflection of the first partial beam, and the first focusing mirror for adjusting the focal position of the first partial beam.
The PCB short-wavelength pulsed laser drilling device according to claim 6, wherein:

The annular optical path module includes: a second mirror group, a second scanning galvanometer, a second focusing mirror and an axicon;

The axicon is installed between the beam splitter and the second reflection mirror group, and shapes the second partial beam emitted by the beam splitter to obtain a ring beam.
PCB short wavelength pulse laser drilling device according to claim 5, is characterized in that:

The laser source includes: a short wavelength pulse laser and a beam expander;

The short-wavelength pulsed laser generates a laser beam, and the beam expander is installed between the short-wavelength pulsed laser and the beam splitter, and the laser beam is subjected to beam area increase processing and collimation processing; the short-wavelength pulsed laser The beam quality M2 factor of the laser is less than 1.3, its wavelength is in the ultraviolet band between 248 and 355nm and the green band between 532 and 515nm, and its pulse repetition frequency is greater than or equal to 90kHz.
The PCB short-wavelength pulsed laser drilling device according to claim 5, wherein:

Both the Gaussian optical path module and the annular optical path module are mounted on the base through a lifting mechanism, and the lifting mechanism is composed of a Z-axis slide rail vertically fixed on the base and a slider driven by a motor;

Both the Gaussian optical path module and the annular optical path module are fixedly mounted on the slider and move vertically along the Z-axis slide rail with the slider;

The PCB short-wavelength pulse laser drilling device further includes a control module, which is respectively connected in communication with the laser source, the Gaussian optical path module, the annular optical path module, the mobile platform and the lifting mechanism;

The control module controls the laser source to start or close by sending instructions to the laser source, the Gaussian light path module, the ring light path module and the lifting mechanism, and the Gaussian light path module and the ring light path module emit light. The parameters of the laser; the control module controls the horizontal movement of the PCB carrying the mobile platform by sending instructions to the mobile platform.
The PCB short-wavelength pulsed laser drilling device according to claim 6, wherein:

The Gaussian optical path module further includes: a beam shaper;

The beam shaper is arranged between the beam splitter and the first reflecting mirror group, and the beam shaper is used for shaping the Gaussian beam into a flat-top beam.