A circuit board hole copper metal heat treatment method and metal heat treatment equipment

Abstract

The present invention discloses a method for heat treating copper metal in circuit board holes and metal heat treatment equipment. The method for heat treating copper metal in circuit board holes specifically uses a laser beam to heat the conductive copper pillar to perform metal heat treatment, and when the laser beam heats the conductive copper pillar, the thermal field temperature at the side wall of the conductive copper pillar is lower than the melting point temperature of the conductive copper pillar. In this way, the laser beam can be used to heat the conductive copper pillars on the circuit board individually to perform metal heat treatment on the conductive copper pillars. The method can improve the metal properties of the conductive copper pillars without destroying the structure of the circuit board, so that the conductive copper pillars can meet the performance requirements of high-heat-generating, high-frequency, and high-speed circuit boards, especially improve the mechanical reliability properties such as flexibility and density of the conductive copper pillars and the high-frequency and high-speed electrical signal transmission performance, thereby improving the thermal stability and electrical signal transmission performance of the circuit board.

Description

Technical Field

[0001] The present invention belongs to the technical field of circuit board processing, and in particular relates to a circuit board hole copper metal heat treatment method and metal heat treatment equipment. Background Art

[0002] With the development of artificial intelligence (AI), the demand for AI and computing server circuit boards, as well as automotive radar high-frequency boards, has increased dramatically. However, computing circuit boards and automotive radar boards generate enormous heat during operation, putting the bonding strength of the blind via bottom under great test, far exceeding that of ordinary blind via circuit boards. Even if there is no copper-carbon alloy at the bottom of the blind via and the electroplated crystal interface is perfect, the via copper (conductive copper pillar) may still break when the circuit board operates at high temperatures. This is related to many factors, including the density of the electroplated copper. In addition, the performance of electroplated copper cannot actually meet the high-speed computing performance requirements of AI. However, there is currently no better way to obtain better electroplated copper that matches the electrical performance requirements of computing power (such as capacitance, resistance, inductance, via copper flexibility, via copper density, etc.). Metal heat treatment of the via copper can greatly improve its flexibility and enhance its connection performance with the conductive copper layer. However, the high-temperature resistance of the insulation layer on the current circuit board is poor, which means that metal heat treatment of the via copper will damage the circuit board's main structure. Summary of the Invention

[0003] In order to solve the above technical problems, one of the objectives of the present invention is to provide a circuit board hole copper metal heat treatment method that can heat only the conductive copper pillars on the circuit board (local heating of a very small area of the circuit board) to perform metal heat treatment.

[0004] In order to achieve the above-mentioned purpose, the technical solution of the present invention is as follows: a method for heat treatment of copper metal in circuit board holes, wherein the circuit board has at least two conductive copper layers, and an insulating layer is sandwiched between two adjacent conductive copper layers. The circuit board has a hole, and a conductive copper pillar is arranged in the hole. The conductive copper pillar passes through the insulating layer and is electrically connected to the conductive copper layers on both sides of the insulating layer. A laser beam is used to heat the conductive copper pillar to perform metal heat treatment, and when the laser beam heats the conductive copper pillar, the thermal field temperature at the side wall of the conductive copper pillar is lower than the melting point temperature of the material of the conductive copper pillar.

[0005] The beneficial effect of the above technical solution is that a laser beam can be used to heat the conductive copper pillars in a very local area on the circuit board to perform metal heat treatment on the conductive copper pillars. This can improve the metal properties of the conductive copper pillars without destroying the structure of the circuit board. It can improve the mechanical reliability such as the flexibility and density of the conductive copper pillars and the high-frequency and high-speed electrical signal transmission performance, thereby improving the thermal stability and electrical signal transmission performance of the circuit board.

[0006] In the above technical solution, the hole is a blind hole that passes through the insulating layer; or the hole is a through hole.

[0007] The beneficial effect of the above technical solution is that the conductive copper pillars can contact all the conductive copper layers to achieve electrical connection.

[0008] In the above technical solution, the heat field heat during the heat treatment of the conductive copper pillar metal is transferred to the insulating layer, and the temperature of the insulating layer is lower than the physical delamination temperature of the insulating layer and the conductive copper layer and / or the conductive copper pillar.

[0009] The beneficial effect of the above technical solution is that, during the metal heat treatment of the conductive copper pillars, the insulating layer near the conductive copper pillars is not damaged. This prevents physical delamination between the insulating and conductive layers of the circuit board during the metal heat treatment of the conductive copper pillars, which can lead to failure and scrapping of the circuit board. Physical delamination refers to the presence of gaps or cracks between the insulating and conductive layers (even if no gap is visible due to the loss of physical adhesion between the materials on both sides of the crack).

[0010] When the hole in the above technical solution is a blind hole, the laser beam is emitted toward the hole mouth end of the conductive copper pillar corresponding to the hole to heat the conductive copper pillar, and / or is emitted toward the conductive copper layer corresponding to the bottom end of the hole to heat the conductive copper layer, and the heat is conducted to heat the conductive copper pillar.

[0011] The beneficial effect of the above technical solution is that: the direction of the thermal field temperature gradient distribution of the conductive copper column can be selected according to actual needs, or two laser beams can be used to heat both ends of the conductive copper column at the same time to obtain faster laser metal heat treatment efficiency and uniformity. The two laser beams can be obtained by splitting the laser beam output by a laser or deflecting it to different optical paths, or they can be laser beams emitted by different lasers.

[0012] The metal heat treatment described in the above technical solution includes at least one of laser annealing, laser normalizing, laser quenching, laser tempering, laser doping and laser cladding.

[0013] The laser annealing, laser normalizing, laser quenching and laser tempering refer to the concepts of annealing, normalizing, quenching and tempering in metal heat treatment. The difference lies in the heating method. The present invention adopts laser heating.

[0014] Laser doping involves depositing another material (solid, liquid, or gaseous) on the surface of a substrate material. Laser heating then allows atoms of the other material to be incorporated into the substrate. In this invention, the substrate is copper, and the doped material can be another metal or non-metal, enabling the conductive copper pillars to achieve the desired mechanical, electrical, and transmission properties.

[0015] Laser cladding is to set other materials, generally metal materials, on the surface of the substrate material. Under the action of laser heating, the atoms of the other materials are clad on the surface of the substrate material to protect the substrate.

[0016] The beneficial effect of the above technical solution is that the conductive copper pillar can be flexibly subjected to metal heat treatment as needed under the heating of the laser beam.

[0017] In the above technical solution, the laser beam heats the conductive copper column in a spatial dimension by point impact heating, scanning motion heating, or a combination of the two.

[0018] The beneficial effect of the above technical solution is that the conductive copper column can be flexibly heated according to laser parameters such as the power of the laser beam, the pulse width, and the laser wavelength. When fixed-point impact heating is used, the thermal field temperature gradient distribution of the conductive copper column is more obvious, while when scanning motion heating is used, the thermal field temperature distribution of the conductive copper column is relatively uniform.

[0019] In the above technical solution, the laser beam heats the conductive copper column in a continuous heating or intermittent heating manner in terms of time dimension.

[0020] The beneficial effect of the above technical solution is that the conductive copper pillar can be flexibly heated according to laser parameters such as the power of the laser beam, the pulse width, and the laser wavelength. When the laser beam power is low, continuous heating can be performed, and when the laser beam power is high, intermittent heating can be performed. However, the purpose is to heat the conductive copper pillar without damaging the insulation layer of the circuit board. In addition, the continuous heating method can obtain a short and high metal heat treatment temperature; intermittent heating obtains a thermal field temperature that lasts for a certain heat treatment temperature or increases the laser heating interval time to obtain a certain degree of high and low temperature cycling effect (the heat of the conductive copper pillar will be conducted and dissipated by the conductive layers on both sides of the insulating material), thereby obtaining better metal heat treatment quality without damaging the insulating material or the bonding strength between the insulating material and the conductive material.

[0021] The field intensity distribution of the projection spot of the heat field applied by the laser beam in the above technical solution is at least one of Gaussian field intensity distribution, flat-top Gaussian field intensity distribution, flat-top field intensity distribution, annular field intensity distribution and polygonal field intensity distribution.

[0022] The beneficial effect of the above technical solution is that the type of laser beam can be flexibly selected according to the characteristics of the laser beam and the heating temperature required for the conductive copper pillar.

[0023] The laser beam described in the above technical solution is a composite laser beam.

[0024] The composite laser beam can be a combination of laser beams with different wavelengths, or different pulse widths, or different laser powers, or different laser pulse repetition frequencies, or different beam divergence angles, or different beam transverse field intensity distributions, and finally a combined laser beam is formed to perform metal heat treatment on the conductive copper pillars of the circuit board.

[0025] The beneficial effect of the above technical solution is that a better heat treatment effect can be obtained by using a composite laser beam to perform metal heat treatment on the conductive copper pillar.

[0026] A second object of the present invention is to provide a circuit board hole copper metal heat treatment device that can perform metal heat treatment on conductive copper pillars on a circuit board.

[0027] To achieve the above objectives, the technical solution of the present invention is as follows: A circuit board hole copper metal heat treatment device, which is used to perform the circuit board hole copper metal heat treatment method described above, comprising a laser, a galvanometer scanning and flat-field focusing device, and a stage. The circuit board is placed on the stage. The laser and the galvanometer scanning and flat-field focusing device are connected. The laser is used to emit the laser beam, and the laser beam is processed by the galvanometer scanning and flat-field focusing device and then emitted to the circuit board to heat the conductive copper pillar.

[0028] The beneficial effect of the above technical solution is that: in this way, the laser beam emitted by the laser can be processed by the galvanometer scanning and flat-field focusing device and directed to the circuit board on the stage, so as to perform metal heat treatment on the conductive copper pillars on the circuit board in a targeted manner. Since there are multiple conductive copper pillars on the circuit board, the stage and the laser beam can be relatively displaced so that the laser beam can perform metal heat treatment on multiple conductive copper pillars, or the laser beam can be multiple beams, so that multiple conductive copper pillars can be simultaneously subjected to metal heat treatment by multiple laser beams.

[0029] The above technical solution also includes an online electrical testing module, which is used to perform electrical performance testing on the electrical connection between the conductive copper column and the conductive copper layer after the metal heat treatment.

[0030] The beneficial effect of the above technical solution is that after the metal heat treatment, the conductive copper pillars on the circuit board can also be tested for electrical performance by the online electrical testing module, so that it can be determined whether the circuit board after the metal heat treatment is qualified.

[0031] The electrical property test in the above technical solution is to test at least one of the current, voltage, capacitance, resistance and inductance of the conductive copper column.

[0032] The beneficial effect of the above technical solution is that it is possible to directly determine whether the circuit board metal is qualified after heat treatment based on the results of the electrical test. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of heat treatment of circuit board metal in Example 1 of the present invention;

[0034] Figure 2 Another schematic diagram of heat treatment of circuit board metal in Example 1 of the present invention;

[0035] Figure 3 Schematic diagram of heat treatment of circuit board metal in Example 2 of the present invention;

[0036] Figure 4 Schematic diagram of the structure of the circuit board in Example 3 of the present invention;

[0037] Figure 5 Schematic diagram of the structure of the circuit board in Example 4 of the present invention;

[0038] Figure 6 Schematic diagram of the structure of the circuit board in Example 5 of the present invention;

[0039] Figure 7 Schematic diagram of the metal heat treatment state of the circuit board hole copper metal heat treatment equipment according to Example 6 of the present invention;

[0040] Figure 8 This is a schematic diagram of the electrical test status of the circuit board hole copper metal heat treatment equipment described in Example 6 of the present invention.

[0041] In the figure: 1. Circuit board; 11. Conductive copper layer; 12. Insulation layer; 121. Insulation ring; 13. Hole; 131. Sub-hole; 14. Conductive copper pillar; 141. Sub-conductive copper pillar; 15. Electroplating layer; 16. Crystal interface; 2. Laser beam; 100. Laser; 200. Galvanometer scanning and flat-field focusing device; 300. Stage; 400. Online electrical measurement module. DETAILED DESCRIPTION

[0042] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention. The following paragraphs describe the present invention in more detail by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in exact proportions. They are only used to facilitate and clearly illustrate the purpose of the embodiments of the present invention.

[0043] This embodiment mainly performs metal heat treatment on the conductive copper pillars on the circuit boards with high heat generation, high frequency and high speed by laser heating. This can improve the toughness of the conductive copper pillars (avoiding the conductive copper pillars from breaking due to brittleness due to heating of the circuit board), and at the same time improve the contact performance of the contact between the conductive copper pillars and the conductive copper layer (avoiding the poor contact caused by gaps at the contact between the conductive copper pillars and the conductive copper layer due to temperature changes), and at the same time improve the connection and transmission performance of the conductive copper pillars for electrical signals.

[0044] On one hand, this embodiment provides a method for heat treatment of copper metal in a circuit board hole, wherein the circuit board 1 has at least two conductive copper layers 11, and an insulating layer 12 is sandwiched between two adjacent conductive copper layers 11. The circuit board 1 has a hole 13, and the conductive copper column 14 passes through the insulating layer 12 and is electrically connected to the conductive copper layers 11 on both sides of the insulating layer 12. The conductive copper column 14 is heated by a laser beam 2 to perform metal heat treatment, and when the laser beam 2 heats the conductive copper column 14, the thermal field temperature at the side wall of the conductive copper column 14 is lower than the melting point temperature of the material of the conductive copper column 14. When the laser beam spot directly hits the conductive copper pillar, due to its high energy, a pit may be etched on the end of the conductive copper pillar (the conductive copper pillar is melted at the etched position), but it is necessary to ensure that the side wall of the conductive copper pillar cannot be melted (because the melting point of the conductive copper pillar is much higher than the destruction temperature of the insulating layer, if the side wall of the conductive copper pillar is melted, the structure of the insulating layer will inevitably be damaged, causing the circuit board to fail). When the conductive copper pillar described in this embodiment is heated by the laser beam, its thermal field temperature is distributed in a gradient in both the longitudinal and radial directions, and the heat diffuses along the gradient.

[0045] In this embodiment, the laser beam heating the conductive copper pillar requires controlling the heating rate, intensity, and duration of the laser beam to regulate the thermal field temperature distribution, temperature level, and duration of the metal heat treatment of the conductive copper pillar. The insulating material of the insulating layer in this embodiment can be any one of silicon, ceramic, glass, and polymer insulating materials, or a combination of any of these materials.

[0046] Specifically, in this embodiment, the number of conductive copper layers is n, and the number of insulating layers is n-1, where n is a positive integer and n≥2.

[0047] In the above technical solution, the hole 13 is a blind hole, and the hole 13 passes through the insulating layer 12; or the hole 13 is a through hole, so that the conductive copper column can contact all the conductive copper layers to achieve electrical connection; specifically, when the hole is a through hole, the entire circuit board is directly penetrated (in this case, the hole can be a straight hole or a trumpet-shaped hole), and when the hole is a blind hole, the hole passes through all the insulating layers, but only a layer of conductive copper layer away from its hole end is not penetrated (in this case, the bottom end of the blind hole can be recessed into the conductive copper layer, or can be flush with the side of the conductive copper layer close to its hole end).

[0048] When the hole is a through hole, both sides of the circuit board have an electroplating layer 15, and the laser beam can heat the conductive copper column from either side of the circuit board; when the hole is a blind hole, the circuit board can only have an electroplating layer 15 on one side corresponding to the opening end of the hole.

[0049] When the hole 13 in the above technical solution is a blind hole, the laser beam 2 is emitted toward the hole mouth end of the conductive copper pillar 14 corresponding to the hole 13 to heat the conductive copper pillar 14, and / or toward the conductive copper layer 11 corresponding to the bottom end of the hole 13 to heat the conductive copper layer 11, and the heat is conducted to heat the conductive copper pillar 14. The two outermost conductive copper layers of the circuit board can be defined as the first conductive copper layer and the second conductive copper layer, respectively. The hole mouth end is close to the first conductive copper layer and penetrates the first conductive copper layer, and the bottom end of the hole is close to the first conductive copper layer. The laser beam is close to the second conductive copper layer but does not penetrate the second conductive copper layer. At this time, the laser beam can heat the end of the conductive copper pillar close to the first conductive copper layer, and can also heat the position of the second conductive copper layer close to the conductive copper pillar. At this time, the heat is conducted to the conductive copper pillar through the second conductive copper layer. Of course, two laser beams can also be used to heat the conductive copper pillar, one laser beam heats the end of the conductive copper pillar close to the first conductive copper layer, and the other laser beam heats the position of the second conductive copper layer close to the conductive copper pillar, so that the heating effect of the conductive copper pillar is better.

[0050] The crystal interface 16 is the contact surface between the corresponding end of the conductive copper pillar and the second conductive copper layer. The heating method of the conductive copper pillar by a single laser beam is preferably selected so that the crystal interface 16 has a higher temperature (in this way, the crystal interface 16 is effectively subjected to laser metal heat treatment). For example, if the length of the conductive copper pillar is L1, and the distance from the side of the second conductive copper layer away from the conductive copper pillar to the conductive copper pillar is L2, when L1>L2, the laser beam can heat the position of the second conductive copper layer close to the conductive copper pillar, and the heat is conducted to the conductive copper pillar through the second conductive copper layer. When L1<L2, the laser beam can heat the end of the conductive copper pillar close to the first conductive copper layer.

[0051] Specifically, in this embodiment, when the hole 13 is a blind hole, its aperture can be gradually reduced from the hole mouth to the hole bottom, so as to improve the electrical connection performance of the conductive copper column in the hole and the conductive copper layer. Furthermore, the hole can be a first-order blind hole, a second-order blind hole, a multi-order blind hole, a cross-layer blind hole or a stacked hole. When the hole is a second-order blind hole, a multi-order blind hole, a cross-layer blind hole or a stacked hole, the insulating layer has at least two layers (i.e., n>2).

[0052] In the above technical solution, the heat field during the metal heat treatment of the conductive copper pillar 14 is transferred to the insulating layer 12, and the temperature of the insulating layer 12 is lower than the physical delamination temperature of the insulating layer 12 and the conductive copper layer 11 and / or the conductive copper pillar 14 (for a circuit board, if its insulating layer and the conductive copper layer or the conductive copper pillar are physically delaminated, it can be considered that the circuit board has failed, and the reasons for the physical delamination of the insulating layer and the conductive copper layer or the conductive copper pillar include the insulating layer being softened, melted or carbonized due to high temperature, etc.).

[0053] The metal heat treatment described in the above technical solution includes at least one of laser annealing, laser normalizing, laser quenching, laser tempering, laser doping and laser cladding, so that the conductive copper column can be flexibly subjected to metal heat treatment as needed under the heating of the laser beam; specifically, the specific process of the laser doping or laser cladding treatment is to coat or spray the material to be doped or clad on the conductive copper column, and use the laser beam to scan the end of the conductive copper column so that the material to be doped or clad is incorporated into the conductive copper column or clad on the surface of the conductive copper column under the scanning of the laser beam, wherein the material to be doped or clad can be a rare earth element, or a corrosion-resistant element such as titanium, nickel, chromium, etc., of course, it is not limited thereto. Specifically, the core of the above metal heat treatment is to use a laser beam to heat the conductive copper column, thereby modifying the conductive copper column, and the modification process is carried out directly on the circuit board.

[0054] In the above technical solution, the laser beam 2 heats the conductive copper column 14 in space by fixed-point impact heating, scanning motion heating, or a combination of the two. In this way, the conductive copper column can be flexibly heated according to the power of the laser beam. When fixed-point impact heating is adopted, the thermal field temperature gradient distribution of the conductive copper column is more obvious, while when scanning motion heating is adopted, the thermal field temperature distribution of the conductive copper column is relatively uniform.

[0055] In the above technical solution, the laser beam 2 heats the conductive copper column 14 in a continuous heating or intermittent heating manner. In this way, the conductive copper column can be flexibly heated according to the power of the laser beam. When the laser beam power is low, continuous heating can be performed, and when the laser beam power is high, intermittent heating can be performed. However, the purpose is to heat the conductive copper column without damaging the insulating layer of the circuit board.

[0056] In the above technical solution, the field intensity distribution of the projection spot of the thermal field applied by the laser beam 2 is at least one of a Gaussian field intensity distribution, a flat-top Gaussian field intensity distribution, a flat-top field intensity distribution, a circular field intensity distribution and a polygonal field intensity distribution. In this way, the type of laser beam can be flexibly selected according to the characteristics of the laser beam and the heating temperature requirements of the conductive copper column.

[0057] The laser beam 2 described in the above technical solution is a composite laser beam, so that the laser beam can have at least two waveforms, at least two wavelengths or at least two pulse widths, which can be flexibly composited to meet the metal heat treatment needs of the conductive copper column.

[0058] The laser beam described in this embodiment is a continuous laser or a pulsed laser, wherein any laser light source can be applied to this embodiment, specifically a gas laser or a solid laser; specifically, it can be a semiconductor laser, a carbon dioxide laser, a fiber laser, a semiconductor-pumped solid-state laser, a continuous wave laser, a pulsed laser, a quasi-continuous wave laser, a Q-switched laser, a mode-locked ultrafast laser or a seed-amplified continuous and pulsed laser, etc., which will not be described in detail here.

[0059] The wavelength of the laser beam in this embodiment may include at least one of far-infrared light, infrared light, visible light, ultraviolet light and deep ultraviolet laser wavelengths; the pulse width of the laser beam may be continuous laser, millisecond, microsecond, nanosecond, picosecond or femtosecond pulse width.

[0060] In this embodiment, n=2 can be used as an example. In this case, there are two conductive copper layers and one insulating layer. Figure 2 As shown, when the hole is a through hole (the aperture of the hole can be uniform at all locations, and of course, the hole can also be a trumpet-shaped hole), both sides of the circuit board have an electroplating layer 15, and the laser beam can heat the conductive copper column from either side of the circuit board; or as Figure 1 As shown, when the hole is a blind hole, the electroplating layer 15 is provided on only one side of the circuit board corresponding to the opening end of the hole, wherein Figure 1 For example, the thickness of the two conductive copper layers is 12 microns, the insulating layer is a high-speed material for the circuit board insulating layer with a thickness of 75 microns, and the hole is a blind hole (the aperture of the hole can be consistent at all places. Of course, the aperture can also gradually decrease from the open end to the bottom of the hole. The specific aperture of the open end is 150 microns, and the aperture of the bottom end is 120 microns. After chemical copper deposition and hole-filling electroplating, the hole is filled with conductive copper pillars, and then a copper electroplating layer 15 is electroplated on the conductive copper layer at the open end, wherein the thickness of the electroplating layer can be 10 microns. During the metal heat treatment, a 50W, 100KHz green laser is used to output a laser beam 2 with a pulse width of 30 nanoseconds. The heating spot of the laser beam 2 adopts a circular flat-top design, the spot size is 60 microns, and the heating time is set to 5 milliseconds. Due Figure 1L2 is less than L1 (i.e. the conductive copper layer at the hole opening end is farther away from the crystal interface 16), and the crystal interface 16 is the area that needs improvement the most, so the laser beam 2 is aligned with the hole from the side of the circuit board away from the hole opening end to heat from the bottom of the hole.

[0061] in, Figure 1 and Figure 2 The middle dotted line represents the thermal field distribution state when the laser beam heats the conductive copper column.

[0062] In this embodiment, it is also possible to Figure 2 On the basis of the corresponding scheme, the conductive copper pillar can also be electroplated and attached to the hole. In this case, the conductive copper pillar is in a groove shape as a whole and covers the side walls and bottom walls of the hole (in this case, the electroplating layer and the conductive copper pillar are electroplated at the same time. Since the electroplating speed in the hole is faster, the thickness of the conductive copper pillar is greater than the thickness of the electroplating layer after the electroplating process is completed). For details, see Figure 3 As shown, the insulating layer can be a PI polyimide insulating material with a thickness of 25 microns. When the aperture of the hole gradually decreases from the open end to the bottom end of the hole, the aperture of the open end of the hole can be 100 microns, and the aperture of the bottom end of the hole can be 80 microns. After the black hole and electroplating processes, a groove-shaped conductive copper column and an electroplating layer (10 microns) are formed. In this embodiment, a 30-watt, 100-kHz infrared laser is used to output a laser beam 2 with a pulse width of 120 nanoseconds. The heating spot of the laser beam 2 adopts a circular flat-top design with a spot size of 60 microns. The heating time is set to 5 milliseconds. The laser beam 2 is emitted towards the open end of the blind hole to heat the conductive copper layer (since the conductive copper column is groove-shaped in this embodiment, the inner bottom of the conductive copper column is closer to the crystal interface 16); in this preferred embodiment, it is also possible to consider providing a layer of electroplating layer ( Figure 3 Not marked).

[0063] In this embodiment, it is also possible to Figure 2 Based on the corresponding scheme, such as Figure 4 As shown, the insulating layer in this embodiment can be multi-layer. Specifically, taking n=3 as an example, the insulating layer is provided with 2 layers. The hole can be a blind hole, and the aperture of the hole can gradually decrease from the open end to the bottom end of the hole (in this embodiment, since the hole passes through two layers of conductive copper layers, it is actually a second-order blind hole).

[0064] This embodiment can also Figure 4 Based on the corresponding scheme, such as Figure 5 As shown, if the conductive copper layer in the middle is disconnected from the conductive copper column, and the two are separated by a cross-layer insulating layer for insulation treatment (at this time, the two insulating layers are connected at the blind hole to form an insulating ring 121 to separate the conductive copper layer in the middle from the conductive copper column for insulation treatment), then the hole is a cross-layer blind hole.

[0065] like Figure 6 As shown, in this embodiment, when the insulating layer has multiple layers and the hole is a blind hole, in addition to the conductive copper layer at the bottom of the hole, starting from the hole mouth end, each conductive copper layer and the adjacent insulating layer form a plate group, and an electroplating layer is added between adjacent plate groups (the electroplating layer is between the conductive copper layer and the insulating layer, and no electroplating layer is added between the conductive copper layer and the insulating layer of the same group, and no electroplating layer is added between the conductive copper layer at the bottom of the hole and the adjacent insulating layer), a sub-hole 131 is independently set in each plate group, and the sub-holes 131 on the multiple plate groups are aligned with each other, and each sub-hole 131 is trumpet-shaped, and two adjacent sub-holes 131 are aligned with each other. 1 is separated by an electroplating layer, and at this time, multiple mutually aligned sub-holes 131 form the hole (the hole is in an inverted tower shape as a whole, which is a stacked hole), and each sub-hole 131 is filled with a sub-conductive copper pillar 141, and adjacent sub-conductive copper pillars 141 are connected by the electroplating layer therebetween. At this time, multiple sub-conductive copper pillars 141 are connected through the electroplating layer to form a conductive copper pillar. In this embodiment, the conductive copper pillar after metal heat treatment has better mechanical contact performance with the conductive copper layer, and it has better toughness. Therefore, when the circuit board is in a high temperature operating state, it will not expand due to temperature increase, resulting in cracks and the like between the conductive copper layer.

[0066] like Figure 7 and Figure 8 As shown, another aspect of this embodiment provides a circuit board hole copper metal heat treatment device, which is used to perform the circuit board hole copper metal heat treatment method described above, including a laser 100, a galvanometer scanning and flat field focusing device 200 and a stage 300, the circuit board 1 is placed on the stage 300, the laser 100 and the galvanometer scanning and flat field focusing device 200 are connected, the laser 100 is used to emit the laser beam 2, and the laser beam 2 is processed by the galvanometer scanning and flat field focusing device 200 and then emitted to to the circuit board 1 to heat the conductive copper pillar 14, so that the laser beam emitted by the laser can be processed by the galvanometer scanning and flat-field focusing device and directed to the circuit board on the stage, so as to perform metal heat treatment on the conductive copper pillar on the circuit board in a targeted manner. Since there are multiple conductive copper pillars on the circuit board, the stage and the laser beam can be relatively displaced so that the laser beam can perform metal heat treatment on multiple conductive copper pillars, or the laser beam can be multiple beams, so that multiple conductive copper pillars can be simultaneously subjected to metal heat treatment by multiple laser beams.

[0067] The above technical solution also includes an online electrical testing module 400, which is arranged next to the stage 300 and is used to perform electrical performance testing on the electrical connection between the conductive copper pillars 14 and the conductive copper layer 11 after the metal heat treatment. In this way, after the metal heat treatment, the conductive copper pillars on the circuit board can also be electrically tested by the online electrical testing module to determine whether the circuit board after the metal heat treatment is qualified.

[0068] The electrical test in the above technical solution is to test at least one of the current, voltage, capacitance, resistance and inductance of the conductive copper pillar 14, so that whether the circuit board metal is qualified after heat treatment can be directly judged by the result of the electrical test.

[0069] Specifically, the stage in this embodiment has a positioning fixture and / or a suction cup for positioning the circuit board on the stage.

[0070] The stage can be a motion platform, and / or the laser 100 and the galvanometer scanning and flat-field focusing device 200 can also be installed on a motion frame and driven to move by the motion frame. That is, when the circuit board is subjected to metal heat treatment, either the circuit board can move under the action of the stage, or the laser beam can move under the control of the motion frame, or both can move, so that the laser beam can perform metal heat treatment on each conductive copper column on the circuit board; in addition, the stage and / or motion frame described in this embodiment can also use a CCD visual positioning module or an X-ray transmission positioning module to enable the laser beam and the conductive copper column to be accurately aligned during the movement process. These are all existing technologies and will not be elaborated here.

[0071] In this embodiment, the stage may have a metal heat treatment station and an electrical testing station. When the circuit board is in the metal heat treatment station, the laser beam emitted by the laser 100 and the galvanometer scanning and flat-field focusing device 200 can heat the conductive copper pillar. After the metal heat treatment of the circuit board is completed, the stage can move the circuit board to the electrical testing station so that the online electrical testing module 400 can perform a power-on test on the circuit board (mainly to determine whether the circuit board is qualified after the metal heat treatment, because the circuit board may be scrapped due to the metal heat treatment during the metal heat treatment process).

[0072] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A method for heat treating copper metal in a circuit board hole, wherein the circuit board (1) has at least two conductive copper layers (11), and an insulating layer (12) is sandwiched between the two adjacent conductive copper layers (11), the circuit board (1) has a hole (13), a conductive copper column is arranged in the hole (13), and the conductive copper column (14) passes through the insulating layer (12) and is electrically connected to the conductive copper layers (11) on both sides of the insulating layer (12), characterized in that: The conductive copper pillar (14) is heated by a laser beam (2) to perform metal heat treatment, and when the laser beam (2) heats the conductive copper pillar (14), the thermal field temperature at the side wall of the conductive copper pillar (14) is lower than the melting point of the material of the conductive copper pillar (14); the hole (13) is a blind hole, and the hole (13) passes through the insulating layer (12); the laser beam (2) is emitted toward the hole end of the conductive copper pillar (14) corresponding to the hole (13) to heat the conductive copper pillar (14), or is emitted toward the conductive copper layer (11) corresponding to the bottom end of the hole (13) to heat the conductive copper layer (11), and the heat is conducted to heat the conductive copper pillar (14). The two outermost conductive copper layers of the circuit board are defined as the first conductive copper layer and the second conductive copper layer respectively, and the hole mouth end is close to the first conductive copper layer and penetrates the first conductive copper layer, while the hole bottom end is close to the second conductive copper layer, the crystal interface (16) is the contact surface between the corresponding end of the conductive copper column and the second conductive copper layer, the length of the conductive copper column is L1, and the distance from the side of the second conductive copper layer away from the conductive copper column to the conductive copper column is L2. When L1>L2, the laser beam heats the position of the second conductive copper layer close to the conductive copper column, and the heat is conducted to the conductive copper column through the second conductive copper layer. When L1<L2, the laser beam heats the end of the conductive copper column close to the first conductive copper layer.

2. The circuit board hole copper metal heat treatment method according to claim 1, characterized in that: The heat field during the metal heat treatment of the conductive copper pillar (14) is transferred to the insulating layer (12), and the temperature of the insulating layer (12) is lower than the physical delamination temperature of the insulating layer (12) and the conductive copper layer (11) and / or the conductive copper pillar (14).

3. The circuit board hole copper metal heat treatment method according to claim 1, characterized in that: The metal heat treatment includes at least one of laser annealing, laser normalizing, laser quenching, laser tempering, laser doping and laser cladding.

4. The circuit board hole copper metal heat treatment method according to claim 1, characterized in that: The laser beam (2) heats the conductive copper column (14) in a spatial dimension by performing fixed-point impact heating, scanning motion heating, or a combination of the two.

5. The circuit board hole copper metal heat treatment method according to claim 1, characterized in that: The laser beam (2) heats the conductive copper column (14) in a manner of continuous heating or intermittent heating in a time dimension.

6. The circuit board hole copper metal heat treatment method according to claim 1, characterized in that: The field intensity distribution of the projection spot of the heat field applied by the laser beam (2) is at least one of a Gaussian field intensity distribution, a flat-top Gaussian field intensity distribution, a flat-top field intensity distribution, a ring field intensity distribution, and a polygonal field intensity distribution.

7. The circuit board hole copper metal heat treatment method according to claim 1, characterized in that: The laser beam (2) is a composite laser beam.

8. A circuit board hole copper metal heat treatment device, which is used to perform the circuit board hole copper metal heat treatment method according to any one of claims 1 to 7, characterized in that: The invention comprises a laser (100), a galvanometer scanning and flat-field focusing device (200), and a stage (300), wherein the circuit board (1) is placed on the stage (300), the laser (100) and the galvanometer scanning and flat-field focusing device (200) are connected, the laser (100) is used to emit the laser beam (2), and the laser beam (2) is processed by the galvanometer scanning and flat-field focusing device (200) and then emitted to the circuit board (1) to heat the conductive copper column (14).

9. The circuit board hole copper metal heat treatment equipment according to claim 8, characterized in that: It also includes an online electrical testing module (400) for performing an electrical performance test on the electrical connection between the conductive copper pillar (14) and the conductive copper layer (11) after metal heat treatment.

10. The circuit board hole copper metal heat treatment equipment according to claim 9, characterized in that: The electrical performance test is to test at least one of the current, voltage, capacitance, resistance and inductance of the conductive copper column (14).

Images