Laser processing system, processing method and circuit board assembly

Abstract

The invention provides a laser processing system, a processing method and a circuit board assembly. When the laser processing system acts on the circuit board, the first laser beam emitted by the laser source can ablate the covering film layer of the outer ring without generating a carbonization layer, and the second laser beam emitted by the laser source can ablate the covering film layer located in the center without damaging the bottom copper structure, so that the effects of high precision and no generation of the carbonization layer are achieved. According to the circuit board assembly, the bottom of the opening of the circuit board is provided with the groove, and the contact area of the welding flux is increased through the groove, so that the welding strength of the welding flux can be improved, the thrust of the electronic element is improved, and the connection stability between the electronic element and the circuit board is enhanced.

Description

Technical Field

[0001] This application relates to the technical field of circuit board processing, and more particularly to a laser processing system, processing method, and circuit board assembly. Background Technology

[0002] In the circuit board industry, laser processing technology plays an increasingly important role in the manufacturing of circuit boards for high-end electronic products due to its non-contact nature, high precision, and flexibility. It is particularly suitable for the production of ceramic substrate circuit boards used in high-density interconnect (HDI), radio frequency microwave, power electronics, and high-temperature environments. Specifically, laser applications include: laser drilling, laser direct imaging (LDI), laser cutting, laser hole filling (using laser-activated metal deposition (LAMDA) technology to fill the inner walls of holes and create a seed layer for electroplating), laser micromachining, and laser stripping / deplating.

[0003] Existing lasers include ultraviolet (UV) lasers and CO2 lasers. UV lasers emit wavelengths of approximately 351nm to 355nm. While UV lasers offer high precision, they suffer from defects such as residual coating layers and damage to the underlying copper. CO2 lasers emit wavelengths of approximately 10.6μm, exhibiting high reflectivity on copper surfaces. Therefore, oxidation / browning / blackening treatments are required on the copper surface to allow the surface to absorb the excitation energy, thus achieving the drilling effect. Although CO2 lasers do not damage the copper layer (they are reflected on the copper surface), their large processing area makes them unsuitable for high-precision applications, and they generate significant heat, causing carbonization at the edges. Summary of the Invention

[0004] In view of this, this application proposes a laser processing system to solve at least one of the above problems.

[0005] One embodiment of this application discloses a laser processing system, comprising a laser source, a switching module, a first galvanometer, a second galvanometer, and a third galvanometer. The laser source generates a first laser beam and a second laser beam of different wavelengths; the first laser beam is a UV laser beam, and the second laser beam is a CO2 laser beam. The switching module is disposed in the optical paths of the first and second laser beams and is used to control the passage of either the first or second laser beam. The first galvanometer is disposed in the optical path of the first laser beam emitted from the switching module and is used to reflect the first laser beam. The second galvanometer is disposed in the optical path of the second laser beam emitted from the switching module and is used to reflect the second laser beam. The third galvanometer is disposed in the optical paths of the first laser beam reflected from the first galvanometer and the second laser beam reflected from the second galvanometer, and is used to reflect either the first or second laser beam.

[0006] In one embodiment, the laser processing system further includes a size module for adjusting the spot sizes of the first laser beam and the second laser beam. The size module includes a first beam expander and a second beam expander. The first beam expander is disposed between the switching module and the first galvanometer, and is located in the optical path of the first laser beam. The second beam expander is disposed between the switching module and the second galvanometer, and is located in the optical path of the second laser beam.

[0007] In one embodiment, the wavelength of the first laser beam is 351nm to 355nm, and the wavelength of the second laser beam is 10.0μm to 10.6μm.

[0008] In one embodiment, the switch module includes a first optical shutter and a second optical shutter, wherein the first optical shutter is disposed in the optical path of the first laser beam and the second optical shutter is disposed in the optical path of the second laser beam.

[0009] One embodiment of this application proposes a processing method comprising the following steps: providing a circuit board, the circuit board including a dielectric layer, a circuit layer formed on the surface of the dielectric layer, and a cover film layer covering the circuit layer, the circuit layer including pads; activating a first laser beam to irradiate the circuit board, thereby forming a slot on a portion of the cover film layer corresponding to the pads, and forming a groove on the pads corresponding to the slots, the grooves communicating with the slots, wherein the first laser beam is a UV laser beam; activating a second laser beam to irradiate the circuit board, thereby removing the cover film layer located between the slots and forming an opening communicating with the slots and grooves, wherein the second laser beam is a CO2 laser beam; placing solder in the opening; mounting electronic components on the circuit board, the electronic components being connected to the circuit board through the solder.

[0010] In one embodiment, the depth of the groove is 1 μm to 5 μm along the thickness direction of the circuit board. The width of the groove is 15 μm to 40 μm along the extension direction of the circuit board. The roughness of the exposed pads after the cover film layer between the grooves is 0.1 μm to 2 μm.

[0011] In one embodiment, the width of the groove is the distance at the widest point of the top of the groove along the extension direction of the circuit board, and the highest point of the top of the groove is flush with the surface of the cover film layer between the slots facing the pad.

[0012] In one embodiment, after the opening is formed, the width of the pad covered by the cover film layer along the extension direction of the circuit board is smaller than the width of the groove.

[0013] One embodiment of this application discloses a circuit board assembly manufactured by the processing method described above. The circuit board assembly includes a circuit board, solder, and electronic components. The circuit board includes a dielectric layer, a circuit layer formed on the surface of the dielectric layer, and a cover film layer covering the circuit layer. The circuit layer includes pads. The circuit board has an opening, which includes a slot and a recess communicating with the slot. The slot penetrates the cover film layer corresponding to the pad, and the recess penetrates a portion of the pad corresponding to the slot. The solder is disposed within the opening. The electronic components are mounted on the circuit board and connected to the circuit board via the solder.

[0014] In one embodiment, along the extension direction of the circuit board, the width of the pads covered by the cover film layer is smaller than the width of the groove.

[0015] The laser processing system of this application, by setting up laser sources that can emit lasers of different wavelengths, allows the first laser beam (UV laser beam, short wavelength) emitted by the laser source to act on the circuit board with high precision. Moreover, due to the low temperature effect of the first laser beam, it can ablate the outer cover film layer without producing a carbonized layer. The second laser beam (CO2 laser beam, long wavelength) emitted by the laser source can ablate the cover film layer located in the center of the circuit board without damaging the underlying copper structure. Therefore, the processing method using this laser processing system described in this application has the effects of high precision and no carbonized layer formation.

[0016] The circuit board assembly of this application has a groove at the bottom of the circuit board opening. Compared with the case where the bottom of the opening is a flat surface, the groove increases the contact area of ​​the solder, thereby improving the soldering strength, which in turn improves the thrust of the electronic components, enhances the connection stability between the electronic components and the circuit board, and thus improves the reliability of the circuit board assembly. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a laser processing system according to one embodiment of this application.

[0018] Figure 2 This is a cross-sectional view of a circuit board according to an embodiment of this application.

[0019] Figure 3A In order to be in Figure 2 The diagram shows a cross-sectional view of the circuit board after slots and grooves have been formed.

[0020] Figure 3B for Figure 3A The main plane of the structure shown is illustrated in a schematic diagram of one embodiment.

[0021] Figure 3C for Figure 3AThe main plane of the structure shown is illustrated in another embodiment.

[0022] Figure 3D for Figure 3A The main plane of the structure shown is illustrated in another embodiment.

[0023] Figure 4 In order to be in Figure 3A The diagram shows a cross-sectional view of one embodiment after an opening has been formed in the structure shown.

[0024] Figure 5 In order to be in Figure 3A The diagram shows a cross-sectional view of the structure after an opening has been formed in another embodiment.

[0025] Figure 6 This is a cross-sectional view of a circuit board assembly according to one embodiment of this application.

[0026] Figure 7 This is a cross-sectional view of a circuit board assembly according to another embodiment of this application.

[0027] Explanation of main component symbols

[0028] Laser processing system 100

[0029] Laser source 10

[0030] Switching module 20

[0031] First galvanometer 31

[0032] Second galvanometer 32

[0033] Third galvanometer 33

[0034] Size module 40

[0035] First beam expander 41

[0036] Second beam expander 42

[0037] Circuit board 200

[0038] Dielectric layer 21

[0039] Line layer 22

[0040] Covering membrane layer 23

[0041] Pad 24

[0042] Grooving 230

[0043] Groove 240

[0044] Opening 250

[0045] First Processing Zone 201

[0046] Second Processing Zone 202

[0047] Adhesive layer 231

[0048] Protective layer 232

[0049] Circuit board assembly 300

[0050] Solder 50

[0051] Electronic Components 60

[0052] Depth H

[0053] Width L, W

[0054] The following detailed description, in conjunction with the accompanying drawings, further illustrates the embodiments of this application. Detailed Implementation

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this application pertain. The terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the embodiments of this application. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0056] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0057] It will be understood that when a layer is referred to as "on" another layer, it can be directly on that other layer or there may be an intermediate layer in between. Conversely, when a layer is referred to as "directly on" another layer, there is no intermediate layer. When a component is referred to as "attached to," "mounted to," "set on," or "connected to" another component, it can be directly on that other component or there may be an intervening component. The term "and / or" as used herein includes all and any combination of one or more of the associated listed items.

[0058] Embodiments of this application are described herein with reference to cross-sectional views, which are schematic diagrams of idealized embodiments (and intermediate configurations) of this application. Therefore, variations in the shapes illustrated due to manufacturing processes and / or tolerances are foreseeable. Consequently, embodiments of this application should not be construed as limited to the specific shapes of the areas illustrated herein, but should include, for example, deviations in shape due to manufacturing processes. The areas shown in the figures are merely illustrative, and their shapes are not intended to represent the actual shapes of the illustrated devices, nor are they intended to limit the scope of this application.

[0059] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0060] Please see Figure 1 This application provides a laser processing system 100, which includes a laser source 10, a switching module 20, a first galvanometer 31, a second galvanometer 32, and a third galvanometer 33. The laser source 10 is used to generate a laser beam, specifically, the laser beam includes a first laser beam and a second laser beam with different wavelengths. In this embodiment, the laser source 10 includes a UV laser and a CO2 laser. The UV laser is used to generate the first laser beam (UV laser beam), and the wavelength range of the first laser beam can be 351nm to 355nm. For example, the wavelength of the first laser beam can be 351nm, 352nm, 353nm, 354nm, 355nm, or any value between any two adjacent values ​​mentioned above. The CO2 laser is used to generate the second laser beam (CO2 laser beam), and the wavelength of the second laser beam can be 10.0μm to 10.6μm. For example, the wavelength of the second laser beam can be 10.0 μm, 10.1 μm, 10.2 μm, 10.3 μm, 10.4 μm, 10.5 μm, 10.6 μm, or any value between any two adjacent values ​​mentioned above.

[0061] like Figure 1 As shown, the switch module 20 is located in the optical path of the first laser beam and the second laser beam. That is, if the laser source 10 emits the first laser beam, the first laser beam will enter the switch module 20; if the laser source 10 emits the second laser beam, the second laser beam will also enter the switch module 20. The switch module 20 will allow either the first laser beam or the second laser beam to pass through according to system instructions. The first laser beam and the second laser beam will not exit from the switch module 20 simultaneously.

[0062] Understandably, for ease of understanding, the transmission paths (optical paths) of the first and second laser beams are... Figure 1The first and second laser beams are shown as being transmitted along the dashed lines in the diagram. In the actual laser processing system 100, the transmission paths (optical paths) represented by the dashed lines may not be visible to the naked eye.

[0063] like Figure 1 As shown, the first galvanometer 31 is disposed in the optical path of the first laser beam emitted from the switching module 20, and is used to reflect the first laser beam to the third galvanometer 33, which then reflects the first laser beam to the workpiece to be processed (e.g., ...). Figure 2 The circuit board shown is 200.

[0064] like Figure 1 As shown, the second galvanometer 32 is disposed in the optical path of the second laser beam emitted from the switching module 20, and is used to reflect the second laser beam to the third galvanometer 33, which then reflects the second laser beam to the workpiece to be processed (e.g., ...). Figure 2 The circuit board shown is 200.

[0065] like Figure 1 As shown, the third galvanometer 33 is positioned on the optical paths of the first laser beam reflected from the first galvanometer 31 and the second laser beam reflected from the second galvanometer 32. That is, the third galvanometer 33 is located on both the optical paths of the first and second laser beams. The same third galvanometer 33 can reflect both the first and second laser beams (not simultaneously).

[0066] By setting up laser sources 10 that can emit different wavelengths, the first laser beam (UV laser beam, short wave) emitted by the laser source 10 has high precision when acting on the circuit board 200, and due to the low temperature effect of the first laser beam, it can ablate the outer cover film layer 23 without producing a carbonized layer; the second laser beam (CO2 laser beam, long wave) emitted by the laser source 10 can ablate the cover film layer 23 located in the center of the circuit board 200 without damaging the bottom copper structure, thus achieving both high precision and no carbonized layer.

[0067] In some embodiments, such as Figure 1As shown, the laser processing system 100 also includes a size module 40. The size module 40 can be used to adjust the spot size of the first laser beam (and the second laser beam), for example, it can increase or decrease the size of the first laser beam (and the second laser beam). The spot can be circular or elliptical, etc., and this application is not limited thereto. When the spot is circular, the size of the spot is the diameter of the spot. The size module 40 may include a first beam expander 41 and a second beam expander 42. The first beam expander 41 is disposed between the switching module 20 and the first galvanometer 31, and is located in the optical path of the first laser beam. The first beam expander 41 is used to increase or decrease the size of the first laser beam. The second beam expander 42 is disposed between the switching module 20 and the second galvanometer 32, and is located in the optical path of the second laser beam. The second beam expander 42 is used to increase or decrease the size of the second laser beam. In some embodiments, the size module 40 may be omitted.

[0068] In some embodiments, the switch module 20 may include a first optical shutter and a second optical shutter (not shown). The first optical shutter is disposed in the optical path of the first laser beam. When the first optical shutter is open, the first laser beam can be emitted from the switch module 20; when the first optical shutter is closed, the first laser beam cannot be emitted from the switch module 20. The second optical shutter is disposed in the optical path of the second laser beam. When the second optical shutter is open, the second laser beam can be emitted from the switch module 20; when the second optical shutter is closed, the second laser beam cannot be emitted from the switch module 20.

[0069] Please see Figures 2 to 5 The second aspect of this application provides a processing method for processing a circuit board 200, which includes steps S10 to S50. It is understood that this processing method can be performed using the laser processing system 100 described in the embodiments of this application, or it can be performed using other equipment; this application does not impose any limitations. The processing method described in this application will be described in detail below using the laser processing system 100 described in the embodiments of this application as an example.

[0070] Please see Figure 2 S10, a circuit board 200 is provided, which may be a flexible printed circuit board (FPC). The circuit board 200 includes a dielectric layer 21, a circuit layer 22 formed on the surface of the dielectric layer 21, and a cover film layer 23 covering the circuit layer 22. The circuit layer 22 includes pads 24. In this embodiment, the circuit board 200 includes one dielectric layer 21 and one circuit layer 22; in other embodiments, the circuit board 200 may include multiple dielectric layers 21 and multiple circuit layers 22, with a dielectric layer 21 between adjacent circuit layers 22. Each circuit layer 22 can be connected to the others through conductive vias (not shown). The cover film layer 23 covers the outermost circuit layer 22 and the dielectric layer 21 exposed from the circuit layer 22.

[0071] In some embodiments, such as Figure 2 As shown, the cover film layer (CVL) 23 may include an adhesive layer 231 and a protective layer 232. The adhesive layer 231 is located between the circuit layer 22 and the protective layer 232, covering the circuit layer 22 and the dielectric layer 21 exposed from the circuit layer 22. The adhesive layer 231 may be, but is not limited to, epoxy resin, and the protective layer 232 may be, but is not limited to, polyimide (PI).

[0072] In some embodiments, the circuit board 200 can be manufactured using existing circuit board manufacturing methods. For example, the circuit board 200 can be manufactured by performing steps such as lamination, exposure, development, etching, film removal, and layer addition on a copper-clad laminate. The circuit layer 22 can be formed of copper. The dielectric layer 21 can be made of polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS), liquid crystal polymer (LCP), modified polyimide (MPI), etc.

[0073] Please see Figures 3A to 3D S20, the laser source 10 of the laser processing system 100 is turned on, and the switching module 20 is controlled to emit a first laser beam. In this embodiment, the first laser beam is a UV femtosecond laser emitted by a UV laser (UV laser beam, wavelength 351nm~355nm). After passing through the first beam expander 41 (adjusting the spot size to a suitable size), the first galvanometer 31, and the third galvanometer 33, it irradiates the circuit board 200. The first laser beam ablates the portion of the covering film 23 corresponding to the pad 24, thereby forming a groove 230 in the covering film 23. When the portion of the covering film 23 is completely ablated and exposes part of the surface of the pad 24, the first laser beam continues to ablate the pad 24 exposed from the groove 230, thereby forming a groove 240 on the pad 24. The groove 240 is connected to the groove 230.

[0074] In some embodiments, such as Figure 3A As shown, along the thickness direction of the circuit board 200 (i.e. Figure 3A (Vertical direction in the groove), the depth H of the groove 240 is 1μm to 5μm. For example, the depth H of the groove 240 can be 1μm, 2μm, 3μm, 4μm, 5μm or any value between any two adjacent values ​​mentioned above. The inner surface of the groove 240 is a copper surface, and the roughness (Ra) of the copper surface can be 0.1μm to 2μm.

[0075] In some embodiments, such as Figure 3A As shown, along the extension direction of circuit board 200 (i.e. Figure 3A The horizontal direction (which can be the length or width direction of the circuit board 200) of the groove 240 is 15μm to 40μm. For example, the width L of the groove 240 can be 15μm, 18μm, 20μm, 30μm, 40μm, or any value between any two adjacent values ​​mentioned above. The width L is the distance at the widest point of the top of the groove 240 along the extension direction of the circuit board 200. The highest point of the top of the groove 240 is flush (coplanar) with the surface of the cover film layer 23 between the slots 230 facing the pad 24. In some embodiments, such as Figure 3B As shown, on the main plane of the circuit board 200 (i.e., the surface perpendicular to the thickness direction of the circuit board 200), the circuit board 200 can be divided into a first processing area 201 and a second processing area 202. The first processing area 201 is located outside the second processing area 202 and is arranged around the second processing area 202, which is approximately located at the center of the circuit board 200. In this embodiment, the first processing area 201 and the second processing area 202 are approximately annular, and the first processing area 201 is the processing area of ​​the first laser beam. That is, the slot 230 and the groove 240 can be annular on the main plane of the circuit board 200.

[0076] In some embodiments, such as Figure 3C As shown, the first processing area 201 and the second processing area 202 are roughly square ring-shaped. The first processing area 201 is the processing area of ​​the first laser beam; that is, the slot 230 and the groove 240 can be square ring-shaped on the main plane of the circuit board 200. In some embodiments, such as Figure 3D As shown, the first processing area 201 and the second processing area 202 are roughly irregular rings. The first processing area 201 is the processing area of ​​the first laser beam. That is, the slot 230 and the groove 240 can be irregularly ring-shaped on the main plane of the circuit board 200.

[0077] In some embodiments, it is also possible to... Figures 3B to 3D The second processing area 202 shown is further divided into multiple spaced-apart first processing areas 201, with the area between two adjacent first processing areas 201 forming the second processing area 202. When there are multiple first processing areas 201, the first laser beam sequentially ablates the multiple first processing areas 201, forming multiple spaced-apart annular slots 230 and grooves 240 (e.g., ...). Figure 5 (As shown). The spot size of the first laser beam that ablates each of the first processing zones 201 can be adjusted using the first beam expander 41. The size can be the same or different, thereby forming slots 230 with the same or different sizes.

[0078] Please see Figure 4 S30, the control switch module 20 emits a second laser beam. In this embodiment, the second laser beam is a CO2 laser beam emitted by a CO2 laser (wavelength 10.0μm~10.6μm). After passing through the second beam expander 42 (adjusting the spot size to a suitable size), the second galvanometer 32, and the third galvanometer 33, it irradiates the circuit board 200. The second laser beam ablates the cover film layer 23 located between the slots 230. The blank area left after the cover film layer 23 is removed communicates with the slots 230 and the grooves 240, thereby forming an opening 250. It is understood that after the cover film layer 23 between the slots 230 is removed, the second laser beam will be reflected by the exposed pads 24 (copper layer), and therefore will not damage the exposed pads 24. The exposed pads 24 are flat surfaces with a roughness (Ra) of 0.2μm~3μm, which is basically consistent with the roughness of the original copper.

[0079] Figure 4 The image shows a scenario where the slot 230 (groove 240) is a circle and the pads 24 exposed after the cover film layer 23 between the slots 230 is removed have a flat surface. In other embodiments, such as... Figure 5 As shown, the number of slots 230 can be multiple rings, and correspondingly, the number of grooves 240 can also be multiple rings. After the cover film layer 23 between two adjacent rings of slots 230 is removed by the second laser beam, the remaining blank area is connected with the multiple slots 230 and grooves 240, thereby forming an opening 250.

[0080] In some embodiments, such as Figure 4 and Figure 5 As shown, after the opening 250 is formed, along the extension direction of the circuit board 200, the width W of the pad 24 covered by the covering film layer 23 (adhesive layer 231) is smaller than the width L of the groove 240. This ensures the quality of the pad 24 and the reliability of the connection.

[0081] Please see Figure 6 S40, solder 50 may be provided within the opening 250 by means of printing, but not limited to printing. Solder 50 may be, but is not limited to, solder paste.

[0082] Please continue reading. Figure 6 In step S50, electronic component 60 is mounted on circuit board 200, and electronic component 60 is connected to circuit board 200 via solder 50. In this embodiment, solder 50 is solder paste. After the solder paste is placed in the opening 250, a reflow soldering operation can be performed on the solder paste to melt and solidify it, thereby realizing the soldering and electrical connection between electronic component 60 and circuit board 200 (pad 24).

[0083] In some embodiments, the electronic component 60 can be an active component (also known as an active device) or a passive component (also known as a passive device), and this application does not impose any limitations. Active components can be, but are not limited to, vacuum tubes, transistors, integrated circuits, etc., while passive components can be, but are not limited to, resistors, inductors, capacitors, etc.

[0084] In the processing method of this application embodiment, a groove 240 is formed at the bottom of the opening 250 of the circuit board 200. Compared with the case where the bottom of the opening 250 is a flat surface, the groove 240 increases the contact area of ​​the solder 50, thereby improving the welding strength of the solder 50, thereby increasing the pushing force of the electronic component 60 (the force required to push the electronic component 60 out of the opening 250 in the punching direction during the stamping process), and enhancing the connection stability between the electronic component 60 and the circuit board 200.

[0085] Please see Figure 6 and Figure 7 The third aspect of this application provides a circuit board assembly 300 prepared by the above-described processing method, which includes a circuit board 200, solder 50 and electronic components 60.

[0086] like Figure 6 and Figure 7 As shown, the circuit board 200 includes a dielectric layer 21, a circuit layer 22 formed on the surface of the dielectric layer 21, and a cover film layer 23 covering the circuit layer 22. The circuit layer 22 includes pads 24. In this embodiment, the circuit board 200 includes one dielectric layer 21 and one circuit layer 22; in other embodiments, the circuit board 200 may include multiple dielectric layers 21 and multiple circuit layers 22, with a dielectric layer 21 between adjacent circuit layers 22. The circuit layers 22 can be connected to each other through conductive vias (not shown). The cover film layer 23 covers the outermost circuit layer 22 and the dielectric layer 21 exposed from the circuit layer 22. The circuit board 200 may be a flexible printed circuit board (FPC).

[0087] like Figure 6 and Figure 7 As shown, the circuit board 200 has an opening 250. The opening 250 includes a slot 230 and a groove 240 communicating with the slot 230. The slot 230 is along the thickness direction of the circuit board 200 (i.e., Figure 6 and Figure 7 The groove 240 penetrates the cover film layer 23 corresponding to the pad 24 in the vertical direction of the circuit board 200, and penetrates part of the pad 24 corresponding to the slot 230 along the thickness direction of the circuit board 200 (that is, the groove 240 only penetrates part of the pad 24).

[0088] like Figure 6 and Figure 7As shown, solder 50 is disposed within opening 250. The surface of solder 50 facing away from pad 24 may be higher than the surface of cover film layer 23 facing away from dielectric layer 21, that is, solder 50 may overflow outside opening 250. Solder 50 may be formed from solder paste.

[0089] like Figure 6 and Figure 7 As shown, electronic component 60 is mounted on circuit board 200 and connected to circuit board 200 via solder 50 (mechanical and electrical connection). Electronic component 60 can be an active component or a passive component.

[0090] In some embodiments, such as Figure 6 As shown, on the main plane of the circuit board 200 (i.e., the surface perpendicular to the thickness direction of the circuit board 200), the groove 240 at the bottom of the slot 230 can be a ring, and the surface of the pad 24 between the ring of grooves 230 can be a flat surface. In other embodiments, such as Figure 7 As shown, on the main plane of the circuit board 200, the groove 240 at the bottom of the slot 230 can also be multiple rings, and the surface of the pad 24 between the outermost groove 230 can be a wavy surface.

[0091] In some embodiments, such as Figure 6 and Figure 7 As shown, along the extension direction of the circuit board 200, the width W of the pad 24 covered by the covering film layer 23 (adhesive layer 231) is smaller than the width L of the groove 240. This ensures the quality of the pad 24 and the reliability of the connection.

[0092] In some embodiments, such as Figure 6 and Figure 7 As shown, the cover film layer (CVL) 23 may include an adhesive layer 231 and a protective layer 232. The adhesive layer 231 is located between the circuit layer 22 and the protective layer 232, and covers the circuit layer 22 and the dielectric layer 21 exposed in the circuit layer 22. The adhesive layer 231 may be, but is not limited to, epoxy resin, and the protective layer 232 may be, but is not limited to, PI.

[0093] The laser processing system 100 of this application embodiment, by setting up laser sources 10 that can emit different wavelengths, has a first laser beam (UV laser beam, short wave) emitted by the laser source 10 that acts on the circuit board 200 with high precision. Moreover, due to the low temperature effect of the first laser beam, it can ablate the outer cover film layer 23 without producing a carbonized layer. The second laser beam (CO2 laser beam, long wave) emitted by the laser source 10 can ablate the cover film layer 23 located in the center of the circuit board 200 without damaging the bottom copper structure. Therefore, the processing method using the laser processing system 100 described in this application has the effects of high precision and no carbonized layer.

[0094] The circuit board assembly 300 of this application embodiment has a groove 240 formed by ablation of the bottom of the opening 250 of the circuit board 200 by the first laser beam. Compared with the case where the bottom of the opening 250 is a flat surface, the groove 240 increases the contact area of ​​the solder 50, thereby improving the soldering strength of the solder 50, thereby improving the thrust of the electronic component 60, enhancing the connection stability between the electronic component 60 and the circuit board 200, and thus improving the reliability of the circuit board assembly 300.

[0095] The above description describes some specific embodiments of this application, but in actual applications, the application should not be limited to these embodiments. For those skilled in the art, other modifications and alterations made based on the technical concept of this application should fall within the protection scope of this application.

Claims

1. A laser processing system, characterized in that, include: A laser source, wherein the laser source is used to generate a first laser beam and a second laser beam, the first laser beam being a UV laser beam and the second laser beam being a CO2 laser beam; A switching module is disposed in the optical path of the first laser beam and the second laser beam, and the switching module is used to control the passage of the first laser beam or the second laser beam; A first galvanometer is disposed in the optical path of the first laser beam emitted from the switching module and is used to reflect the first laser beam. The second galvanometer is disposed in the optical path of the second laser beam emitted from the switching module and is used to reflect the second laser beam; and A third galvanometer is disposed on the optical path of the first laser beam reflected from the first galvanometer and the second laser beam reflected from the second galvanometer, and is used to reflect the first laser beam or the second laser beam.

2. The laser processing system as described in claim 1, characterized in that, The laser processing system further includes a size module, which is used to adjust the spot size of the first laser beam and the second laser beam; the size module includes a first beam expander and a second beam expander, the first beam expander being disposed between the switching module and the first galvanometer and located in the optical path of the first laser beam; The second beam expander is disposed between the switch module and the second galvanometer, and is located in the optical path of the second laser beam.

3. The laser processing system as described in claim 1, characterized in that, The wavelength of the first laser beam is 351nm to 355nm, and the wavelength of the second laser beam is 10.0μm to 10.6μm.

4. The laser processing system as described in claim 1, characterized in that, The switching module includes a first optical shutter and a second optical shutter, wherein the first optical shutter is disposed on the optical path of the first laser beam and the second optical shutter is disposed on the optical path of the second laser beam.

5. A processing method, characterized in that, Includes the following steps: A circuit board is provided, the circuit board including a dielectric layer, a circuit layer formed on the surface of the dielectric layer, and a cover film layer covering the circuit layer, the circuit layer including pads; A first laser beam is turned on and irradiates the circuit board, thereby forming a groove on the cover film layer corresponding to the pad, and a groove is formed on the pad corresponding to the groove, the groove being connected to the groove; wherein, the first laser beam is a UV laser beam; The second laser beam is activated and irradiates the circuit board, thereby removing the cover film layer located between the slots and forming an opening that connects with the slots and grooves; wherein, the second laser beam is a CO2 laser beam; Solder is placed inside the opening; Electronic components are mounted on the circuit board and connected to the circuit board via solder.

6. The processing method as described in claim 5, characterized in that, Along the thickness direction of the circuit board, the depth of the groove is 1μm to 5μm; along the extension direction of the circuit board, the width of the groove is 15μm to 40μm; the roughness of the pads exposed after the cover film layer between the grooves is 0.1μm to 2μm.

7. The processing method as described in claim 6, characterized in that, The width of the groove is the distance from the widest point of the top of the groove along the extension direction of the circuit board, and the highest point of the top of the groove is flush with the surface of the cover film layer between the slots facing the pad.

8. The processing method as described in claim 7, characterized in that, After the opening is formed, the width of the pad covered by the cover film layer is smaller than the width of the groove along the extension direction of the circuit board.

9. A circuit board assembly, characterized in that, The circuit board assembly is manufactured by the processing method as described in any one of claims 5 to 8, and the circuit board assembly comprises: A circuit board includes a dielectric layer, a circuit layer formed on the surface of the dielectric layer, and a cover film layer covering the circuit layer, the circuit layer including pads; the circuit board has an opening, the opening including a slot and a groove communicating with the slot, the slot penetrating the cover film layer corresponding to the pads, and the groove penetrating a portion of the pads corresponding to the slot; Solder, disposed within the opening; and Electronic components are mounted on the circuit board and connected to the circuit board via solder.

10. The circuit board assembly as claimed in claim 9, characterized in that, Along the extension direction of the circuit board, the width of the pads covered by the cover film layer is smaller than the width of the groove.

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