Laser welding structure and method capable of avoiding damage to circuit structure
By using a programmable light shield in the laser welding structure to change the shape of the spot, the damage to the glass substrate circuit during the laser welding process is solved, and efficient and accurate welding effect is achieved.
Patent Information
- Application Number
- CN202510239824.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-03
- Publication Date
- 2025-05-30
AI Technical Summary
When laser welding of the glass substrate and the BGA ball, it is difficult to avoid damage to the circuit structure in the glass substrate and cause failure of the glass substrate.
A laser welding structure including a laser, a spot shaping optical path, a focus module, an upper workpiece and a lower workpiece is adopted. The shape of the spot is changed during the scanning welding process through a programmable light shielding plate to avoid damage to the circuit.
Efficient and accurate welding of glass substrates and BGA balls is achieved, which avoids damage to the circuit structure, improves processing efficiency and reduces the probability of glass substrate failure.
Smart Images
Figure CN120076200A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of laser micro-nano processing, and specifically to a laser welding structure and method that can avoid damage to circuit structures. Background Art
[0002] A PCB (Printed Circuit Board) is one of the important components of the electronics industry. Almost all electronic products require the use of a PCB, which is widely used in fields such as communication electronics, medical devices, national defense, and aerospace. As an important basic component in the electronics industry, the demand for PCBs is increasing. If relying solely on traditional manual welding for processing, its production efficiency is far from meeting the requirements. With the development of the electronics industry, in addition to traditional metal substrates such as aluminum and copper, glass fiber can also be used as the substrate material for PCBs. Glass substrates have good mechanical properties and electrical resistance properties, as well as good heat resistance and moisture resistance. Most importantly, due to its transparent characteristics, ultrafast lasers can be used to weld glass substrates and BGA balls.
[0003] Laser technology is one of the major inventions in the 20th century. In recent years, with the rapid development of laser technology, the global laser industry has developed rapidly. Due to the ultrafast action time characteristics and transient high-energy injection characteristics of lasers, as well as the ability to modulate laser interactions, breakthroughs have been made in the application of lasers in various fields.
[0004] As a highly promising microprocessing tool in recent years, femtosecond lasers have the advantages of high peak power, small heat-affected zones in materials, high processing accuracy, and a wide range of applicable materials, and have been widely used in the field of microprocessing. When a femtosecond laser is focused on the interface of a transparent glass material, local modification can be caused at the material interface, melting to form a molten pool, cooling to form a welding zone, and establishing a strong connection of the glass material at the interface, thereby achieving non-contact high-strength and high-precision local welding. Although using ultrafast lasers for welding has the advantages of fast processing, high processing accuracy, and high strength, during the process of scanning and welding a glass substrate, it is difficult to avoid damaging the circuits in the glass substrate, which may further lead to the failure of the glass substrate. Summary of the Invention
[0005] To overcome the deficiencies of the prior art, the present invention provides a laser welding structure and method that can avoid damage to circuit structures, and solves the problems existing in the prior art such as low welding efficiency and easy workpiece failure during welding.
[0006] The technical solutions adopted by the present invention to solve the above problems are as follows:
[0007] A laser welding structure capable of avoiding damage to a circuit structure comprises a laser arranged in sequence along a laser transmission direction, a spot shaping optical path, a focusing module, an upper workpiece, a lower workpiece, and a motion platform arranged below the lower workpiece.
[0008] As a preferred technical solution, the laser generated by the laser is a nanosecond laser, a picosecond laser or a femtosecond laser.
[0009] As a preferred technical solution, the light spot shaping optical path includes two focusing lenses and a programmable light shielding plate arranged between the two focusing lenses.
[0010] As a preferred technical solution, the programmable shading plate includes a plurality of movable electrically controlled displacement blocks.
[0011] As a preferred technical solution, the motion platform is a three-dimensional motion platform, and the motion platform can move independently or in linkage in three degrees of freedom.
[0012] As a preferred technical solution, the focusing module includes a scanning galvanometer, a field lens, and the spot shaping optical path, the focusing module, the scanning galvanometer, the field lens, and the upper workpiece are arranged in sequence along the laser transmission direction.
[0013] As a preferred technical solution, the scanning speed range of the scanning galvanometer is 1mm / s-1000mm / s.
[0014] As a preferred technical solution, the focal length of the field lens (4) is in the range of 70 mm to 90 mm, and the laser defocusing amount is in the range of -100 μm to 100 μm.
[0015] As a preferred technical solution, the upper workpiece is a glass substrate and the lower workpiece is a BGA ball.
[0016] A laser welding method capable of avoiding damage to a circuit structure, using the laser welding structure capable of avoiding damage to a circuit structure, comprises the following steps:
[0017] Step 1: Fix the cleaned upper and lower workpieces and place them on a motion platform to ensure that there is no relative movement between the upper and lower workpieces and the motion platform during the welding process. Adjust the motion platform so that the focal plane of the laser is at the height of the contact surface between the upper and lower workpieces.
[0018] Step 2, using the focusing module to set the welding scanning route;
[0019] Step three, turn on the laser to generate laser, the laser passes through the focusing module and the focusing module in turn, and welds the contact surface of the upper workpiece and the lower workpiece according to the set welding scanning route.
[0020] Compared with the prior art, the present invention has the following beneficial effects:
[0021] (1) Compared with the traditional manual welding for processing glass substrates, the ultrafast laser scanning welding method has higher efficiency in welding glass substrates to BGA balls, causes a smaller heat affected zone in the material, has higher welding precision, and can avoid damaging the circuit structure on the glass substrate;
[0022] (2) The present invention adds a programmable light shield in the optical path. During the scanning welding process, the light shield can change the spot shape, avoiding damaging the circuit during the laser processing, and while ensuring the processing efficiency, it can also minimize the failure probability of the glass substrate as much as possible;
[0023] (3) Compared with the traditional light shield, the programmable light shield of the present invention has the advantage of programmable adjustment. Through programming, the shape of the shaded part can be adjusted in real time according to the circuit shape on the welding route, eliminating the step of replacing the light shield, greatly improving the convenience and efficiency of processing different glass substrates. By changing the shape of the programmable light shield to replace light shields with different shapes, the processing cost is reduced;
[0024] (4) The present invention effectively realizes the rapid welding of glass substrates to BGA balls, that is, it improves the convenience and efficiency of welding glass substrates to BGA balls, and at the same time minimizes the failure probability of the glass substrate during the welding process. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 It is a schematic structural diagram of a laser welding structure that can avoid damage to the circuit structure according to the present invention;
[0026] Figure 2 It is a schematic structural diagram of the light spot shaping optical path;
[0027] Figure 3 It is a schematic diagram of the changes in the light spot shape and the circuit board shape during the welding process.
[0028] Reference numerals in the drawings and their corresponding names: 1 - laser; 2 - light spot shaping optical path; 3 - scanning galvanometer; 4 - field lens; 5 - glass substrate; 6 - BGA ball; 7 - moving platform; 8 - focusing lens; 9 - programmable light shield. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0029] The following will further elaborate on the present invention in detail in conjunction with the embodiments and the drawings, but the embodiments of the present invention are not limited thereto.
[0030] Embodiment 1
[0031] As Figures 1 to 3As shown in the figure, the present invention provides a laser welding method that can avoid damage to important results and circuit structures, which can not only achieve efficient welding of glass substrates and BGA balls, but also avoid laser damage to the circuits on the glass substrates during the welding process. The specific process of method implementation is as follows: Fix the cleaned glass substrate and BGA balls through a special fixture and place them on a three-dimensional motion platform. Adjust the three-dimensional platform so that the focal plane of the laser is at the height of the contact surface between the upper workpiece and the lower workpiece. Design a scanning welding route and program the shape of the light-shielding part of the programmable light-shielding plate according to the shape of the circuit on the welding route. After the laser beam is collimated, it is injected into the scanning galvanometer, and after being emitted, it is focused by a field lens. After changing the spot shape through the programmable light-shielding plate, the glass substrate and BGA balls are welded according to the scanning path set by the galvanometer. High-quality and high-efficiency welding without damaging the circuits on the glass substrate is achieved.
[0032] The present invention specifically includes fixing the cleaned glass substrate and BGA balls through a special fixture, placing them on a three-dimensional motion platform, and adjusting the three-dimensional platform so that the focal plane of the laser is at the height of the contact surface between the upper workpiece and the lower workpiece. Adjust the programmable light-shielding plate according to the circuit shape of the glass substrate. After the laser beam is collimated, it is injected into the scanning galvanometer, and after being emitted, it is focused by a field lens. The glass substrate and BGA balls are welded according to the scanning path set by the galvanometer, and the programmable light-shielding plate will filter out the laser that damages the circuits on the glass substrate. Thus, the welding of the glass substrate and BGA balls is completed without damaging the circuits on the glass substrate.
[0033] A laser encapsulation method for glass substrates that can avoid damage to circuit structures, used for laser welding of glass substrates and BGA balls, includes the following steps:
[0034] Step 1: Fix the cleaned glass substrate and BGA balls through a special fixture and place them on a three-dimensional motion platform to ensure that there is no relative movement between the glass substrate, BGA balls, and the three-dimensional motion platform during the welding process. Adjust the three-dimensional platform so that the focal plane of the laser is at the height of the contact surface between the upper workpiece and the lower workpiece.
[0035] Step 2: Use the galvanometer to set the welding scanning route, and program and adjust the programmable light-shielding plate according to the change of the circuit shape of the glass substrate on the welding route. The programmable light-shielding plate is placed at the conjugate plane of the beam expander group, and the subsequent focusing process will avoid damaging the circuit structure of the glass substrate. At the same time, the shape change speed of the programmable light-shielding plate matches the welding scanning rate to ensure that the laser after passing through the light-shielding plate will not damage the circuits in the glass substrate during the welding process. Select appropriate scanning rates and laser parameters according to the material and thickness of the glass substrate to improve the welding strength.
[0036] Step three, turn on the laser. The laser first changes the laser spot through a spot shaping optical path composed of two focusing lenses and a programmable shading plate, and then vertically enters the incident hole of the scanning galvanometer through a collimated optical path and is emitted from the exit hole of the scanning galvanometer. It is focused by the field lens and the glass substrate and the BGA ball are welded according to the set scanning path.
[0037] Among them, after the laser spot is quickly shaped according to the rapid changes of the circuit, the spot will avoid the circuit part on the glass substrate during the welding process, and will not damage the circuit in the glass substrate or cause the glass substrate to fail. Under the action of the laser, the welding of the glass substrate and the BGA ball is completed.
[0038] Preferably, in step 2, the programmable sunshade material may be an electrochromic material, the light transmittance of which is variable between 0-90%, and can be changed from opaque to transparent. The principle is that after receiving an electrical signal, the ions in the electrochromic material will move under the action of the electric field, causing the optical properties of the material to change, thereby realizing the programming to change the shape of the sunshade.
[0039] Preferably, in step 2, the programmable shading plate material can be a multi-position electrically controlled displacement block, and a specific pattern can be achieved under a building block splicing effect by controlling the movement or non-movement of multiple displacement blocks according to the required pattern. The displacement blocks can all be selected to be highly reflective materials or highly transparent materials to achieve programmable shaping of the light beam.
[0040] Preferably, in step 1, the clamp should ensure that the BGA ball will not slip after being clamped and can adapt to the sizes of different glass substrates.
[0041] Preferably, in step 1, the three-dimensional motion platform is a motion platform with three degrees of freedom, which can move independently or in conjunction on the X, Y, and Z axes, and its main function is to adjust the focal plane.
[0042] Preferably, in step 2, the programming adjustment method needs to have sufficient accuracy to match the welding scanning speed to ensure that when the shape of the circuit changes on the scanning route, the shading plate can change its shape in time.
[0043] Preferably, in step three, the laser may be a high repetition rate nanosecond laser, a picosecond laser or a femtosecond laser.
[0044] Preferably, the scanning galvanometer is a high-speed two-dimensional galvanometer, and the two-dimensional movement of the laser beam can be achieved through the deflection of two reflection mirrors. The scanning speed setting range of the scanning galvanometer is 1mm / s-1000mm / s.
[0045] Preferably, the field lens is a single lens or a set of lenses for controlling and adjusting the propagation direction, beam diameter, and focusing position of the laser beam. The focal length of the field lens (4) ranges from 70 mm to 90 mm, and the laser defocus amount can be set between ±100 μm.
[0046] Preferably, in addition to the glass substrate, the welding object of the present method can also weld other transparent materials containing important structures.
[0047] Example 2
[0048] As Figures 1 to 3 shown, based on Example 1, this example provides a more refined implementation method.
[0049] Aiming at the problems of low welding efficiency of traditional glass substrates and easy failure of glass substrates in laser welding, the present invention provides a laser welding method for glass substrates that can avoid damage to important structures.
[0050] The structure of an example provided by the present invention is shown in the figure, which consists of a high-repetition-rate ultrafast laser 1; a spot shaping optical path 2; a scanning galvanometer 3; a field lens 4; a glass substrate 5; BGA balls 6; and a three-dimensional motion platform 7. Among them, the spot shaping optical path 2 consists of two focusing lenses 8 and a programmable light shield 9.
[0051] In this example, the high-repetition-rate ultrafast laser 1, the spot shaping optical path 2, the scanning galvanometer 3, and the field lens 4 are located on the same optical path. The laser first passes through the spot shaping optical path 2. In this optical path, after being focused by the front focusing lens 8 first, the beam changes the spot shape through the programmable light shield 9 at the focusing position, and finally returns to a parallel optical path through the rear focusing lens 8. Subsequently, the laser enters the scanning galvanometer 3, and the scanning galvanometer 3 controls the two-dimensional movement of the optical path through the internal mirror to make it vertically enter the field lens 4. After being focused by the field lens 4, the laser is focused on the contact surface between the glass substrate 5 and the BGA balls 6. During the processing, the workpiece remains stationary, and the scanning galvanometer and the field lens move the spot to complete the scanning welding. In addition, a focusing lens can also be used to replace the scanning galvanometer 3 and the field lens 4. In this method, the spot remains stationary during the processing, and the workpiece is driven by the three-dimensional motion platform 7 to move to achieve scanning welding.
[0052] After the optical path is debugged, the cleaned glass substrate 5 and the BGA balls 6 are fixed on the three-dimensional motion platform 7 through a fixture, and the focal plane of the laser is adjusted to be at the height of the contact surface between the glass substrate 5 and the BGA balls 6 by adjusting the motion platform 7. The scanning welding route is set by using the galvanometer, and the programmable light shield is programmed and adjusted according to the change of the circuit shape on the welding route. The shape of the light-shielding part of the programmable light shield 9 will be matched with the circuit shape in the welding route in real time to ensure that the laser after spot shaping will not damage the circuit. As Figure 3As shown, during the welding process, the shape of the light-shielding plate will match the change in the shape of the circuit on the scanning route, so as to adjust the shape of the light spot in real time and avoid damaging the circuit structure on the PCB board. Select appropriate scanning speed and laser parameters according to the material and thickness of the glass substrate to ensure the welding strength. After all preparations are completed, turn on the laser 1. After the laser beam passes through the light spot shaping optical path 2, it vertically enters the incident hole of the scanning galvanometer 3 and exits from the exit hole of the scanning galvanometer 3, and is focused by the field lens 4 on the contact surface height of the glass substrate 5 and the BGA ball 6 placed on the moving platform 7. At the same time, through the scanning galvanometer 3 and the field lens 4, the focused light spot moves along the set scanning route within the contact surface of the glass substrate 5 and the BGA ball 6. The programmed shape of the light-shielding plate will match the change in the shape of the circuit on the scanning route, so as to adjust the shape of the light spot in real time, so as to complete the welding of the glass substrate 5 and the BGA ball 6 without damaging the circuit on the glass substrate 5.
[0053] It should be noted that the high-repetition-rate ultrafast laser 1 in this embodiment can be realized by a laser with a repetition frequency above 10 kHz.
[0054] As described above, the present invention can be preferably realized.
[0055] All features disclosed in all embodiments in this specification, or all steps in all methods or processes implicitly disclosed, except for mutually exclusive features and / or steps, can be combined and / or extended and replaced in any way.
[0056] The above is only a preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention. According to the technical essence of the present invention, within the spirit and principle of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiments still fall within the protection scope of the technical solution of the present invention.
Claims
1. A laser welding structure capable of avoiding damage to a circuit structure, characterized in that: It comprises a laser (1) arranged in sequence along a laser transmission direction, a light spot shaping optical path (2), a focusing module, an upper workpiece, a lower workpiece, and a motion platform (7) arranged below the lower workpiece.
2. A laser welding structure capable of avoiding circuit structure damage according to claim 1, characterized in that: The laser generated by the laser (1) is nanosecond laser, picosecond laser or femtosecond laser.
3. A laser welding structure capable of avoiding circuit structure damage according to claim 1, characterized in that: The light spot shaping optical path (2) comprises two focusing lenses (8) and a programmable light shielding plate (9) arranged between the two focusing lenses (8).
4. A laser welding structure capable of avoiding damage to a circuit structure according to claim 3, characterized in that: The programmable shading plate (9) comprises a plurality of movable electrically controlled displacement blocks.
5. The laser welding structure capable of avoiding circuit structure damage according to claim 1, characterized in that: The motion platform (7) is a three-dimensional motion platform, and the motion platform (7) can move independently or in linkage in three degrees of freedom.
6. The laser welding structure capable of avoiding damage to the circuit structure according to claim 1, characterized in that: The focusing module comprises a scanning galvanometer (3), a field lens (4), and the light spot shaping optical path (2), the focusing module, the scanning galvanometer (3), the field lens (4), and an upper workpiece are arranged in sequence along the laser transmission direction.
7. A laser welding structure capable of avoiding damage to a circuit structure according to claim 6, characterized in that: The scanning speed range of the scanning galvanometer (3) is 1 mm / s-1000 mm / s.
8. The laser welding structure capable of avoiding damage to the circuit structure according to claim 6, characterized in that: The focal length of the field lens (4) is in the range of 70 mm to 90 mm, and the laser defocusing amount is in the range of -100 μm to 100 μm.
9. A laser welding structure capable of avoiding circuit structure damage according to any one of claims 1 to 8, characterized in that: The upper workpiece is a glass substrate (5), and the lower workpiece is a BGA ball (6).
10. A laser welding method capable of avoiding damage to a circuit structure, characterized in that: Using a laser welding structure capable of avoiding damage to a circuit structure as claimed in any one of claims 1 to 8 comprises the following steps: Step 1: Fix the cleaned upper workpiece and lower workpiece and place them on a motion platform (7) to ensure that the upper workpiece, the lower workpiece and the motion platform (7) do not move relative to each other during the welding process, and adjust the motion platform (7) so that the focal plane of the laser is located at the height of the contact surface between the upper workpiece and the lower workpiece; Step 2, using the focusing module to set the welding scanning route; Step three, turning on the laser (1) to generate laser light, the laser light passes through the focusing module and the focusing module in sequence, and performs welding on the contact surface of the upper workpiece and the lower workpiece according to the set welding scanning route.