Laser drilling method for aluminum-based PCB

Abstract

The invention discloses a laser drilling method for an aluminum-based PCB, and relates to the technical field of aluminum-based PCB machining. The method comprises the following steps: a, cutting and blanking an aluminum substrate; b, mechanically punching by using a punching machine to form a mechanical through hole; c, an adhesive film matched with the aluminum substrate in size is prepared, and adhesive film through holes matched with the mechanical through holes in position are formed in the adhesive film; d, the aluminum substrate is covered with the adhesive film, the adhesive film and the aluminum substrate are bonded, and the adhesive film through hole is aligned with the mechanical through hole; e, coating epoxy resin, and filling the adhesive film through holes and the mechanical through holes with the epoxy resin; f, after the epoxy resin is cured, the adhesive film is torn off, and board grinding is carried out, so that the epoxy resin protruding out of the mechanical through hole is flush with the aluminum substrate; g, punching the through hole filled with the epoxy resin by using CO2 laser; the mechanical through hole is provided with burrs and a rough inner wall; the purpose that the aluminum-based PCB is perforated through low-power CO2 laser, and the inner wall is smooth and free of sagging is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum-based PCB board processing, and in particular to a laser drilling method for an aluminum-based PCB board. Background Art

[0002] Aluminum-based PCB is a printed circuit board that uses aluminum as the main substrate, which has good thermal conductivity and electromagnetic shielding effect. Its structure usually consists of a circuit layer, an insulating layer and an aluminum base. This material is widely used in the electronics industry, including LED lighting, power electronics, automotive electronics, communication equipment and solar cells.

[0003] The punching process of aluminum-based PCB boards is different from that of ordinary FR-4 PCB boards, mainly due to the material properties of aluminum substrates.

[0004] Among them, the advantages of aluminum-based PCB boards mainly include excellent heat dissipation performance. Aluminum is a good thermal conductor and can effectively transfer heat away from important components, thereby reducing harmful effects on circuit boards.

[0005] Most aluminum substrates are punched mechanically, and the problem caused by mechanical punching is that the inner wall of the through hole is rough and has burrs. In the process of covering the insulating layer and depositing copper, it is easy to cause the copper layer to be perforated or the copper layer thickness to be uneven due to the rough inner wall of the through hole.

[0006] In addition to mechanical drilling, laser drilling is also possible. Because aluminum-based PCBs have excellent heat dissipation performance, laser drilling is required to be performed at high power during the laser drilling process to prevent the aluminum substrate from dissipating heat too quickly and affecting the gasification and melting of the aluminum material in the through hole. High-power laser drilling equipment has strict requirements for equipment, and high-specification laser drilling equipment is required to efficiently drill aluminum-based PCBs. In addition, when using high-power lasers for drilling, it is easy to cause severe carbonization of the edge of the hole wall of the aluminum substrate, which seriously damages the uniformity and smoothness of the hole wall.

[0007] Generally speaking, when drilling aluminum substrates, since CO2 lasers generate a lot of heat, UV lasers are generally used to perform precise drilling operations on aluminum substrates. However, the equipment cost of UV lasers is higher than that of CO2 laser drilling equipment. Therefore, the choice of laser light source will seriously limit the scale of aluminum substrate drilling plants. Summary of the invention

[0008] The object of the present invention is to provide a laser drilling method for an aluminum-based PCB board, so as to achieve the purpose of drilling the aluminum-based PCB board with a low-power CO2 laser and making the inner wall smooth and free of sag.

[0009] In order to achieve the above object, the present invention adopts the following technical means: A laser drilling method for an aluminum-based PCB board comprises the following steps: a. Cutting and blanking of aluminum substrate; b. Use a punching machine to mechanically punch holes to form mechanical through holes; c. preparing a film having a size matching that of the aluminum substrate, and constructing film through holes on the film that match the positions of the mechanical through holes; d. Cover the adhesive film on the aluminum substrate to allow the two to bond and align the adhesive film through-holes with the mechanical through-holes; e. Apply epoxy resin to fill the film through-holes and mechanical through-holes; f. After the epoxy resin is cured, tear off the film and grind the board to make the epoxy resin protruding from the mechanical through hole flush with the aluminum substrate; g. Drilling the through holes filled with epoxy resin using a CO2 laser; The mechanical through hole has a burred and rough inner wall.

[0010] Preferably, the diameter of the adhesive film through hole is larger than the diameter of the mechanical through hole.

[0011] Furthermore, the adhesive film is a polyethylene elastic film, and the through holes of the adhesive film are constructed by laser punching. When the adhesive film is punched, the adhesive film is clamped between a pair of heat sinks, and the heat sinks are constructed with through holes for laser to pass through.

[0012] Furthermore, the adhesive film is bonded to the aluminum substrate by a vacuum laminator.

[0013] Furthermore, the thickness of the adhesive film is 0.06 mm to 0.08 mm, and the through hole of the adhesive film is a circular hole.

[0014] Furthermore, after completing step b, a rough grinding needle is inserted into the mechanical through hole to form a rough inner wall with burrs.

[0015] Furthermore, in step f, the epoxy resin is cured in a vacuum environment.

[0016] Furthermore, in step g, the focal plane of the CO2 laser is set below the aluminum substrate.

[0017] Furthermore, the CO2 laser is a pulsed laser, and the pulse number of the CO2 laser is 150-200 Hz.

[0018] During use, the present invention has the following beneficial effects: After the epoxy resin is cured, a low-power CO2 laser is used to drill holes. Since the ablation limit of epoxy resin is significantly lower than that of the aluminum substrate, when the epoxy resin in the mechanical through hole is ablated, it will not cause serious carbonization near the mechanical through hole of the aluminum substrate due to excessive energy. In addition, the thermal conductivity of epoxy resin is significantly lower than that of the aluminum substrate itself. Therefore, after the drilling laser contacts the epoxy resin, the heat dissipates more slowly than when it directly contacts the aluminum substrate. Therefore, compared with directly using the laser to act on the aluminum substrate, the power of directly ablating the epoxy resin with the laser can be significantly lower than that of directly ablating the substrate itself, thereby achieving the purpose of drilling holes in the aluminum substrate using a low-power laser.

[0019] Moreover, after the epoxy resin is filled in the mechanical through hole, it can also complement the aluminum substrate. When the through hole is formed in the epoxy resin, the residual heat of the epoxy resin itself can be quickly conducted away by the aluminum substrate, thereby effectively avoiding the problem of the inner wall of the through hole being sagged due to the long-term retention of the residual heat of the epoxy resin after the through hole is formed, resulting in the problem of the inner wall being not smooth.

[0020] At the same time, the burrs and rough inner walls of the mechanical through holes of the present application can improve the bonding between the inner walls of the mechanical through holes and the epoxy resin, and can also simplify the mechanical drilling steps, so that even low-precision mechanical drilling can still meet the requirements, thereby reducing the requirements and costs of factory construction. In addition, there is no need to drill and polish the inner walls of the mechanical through holes, which can also reduce the production process. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0022] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0024] Example 1 A laser drilling method for an aluminum-based PCB board comprises the following steps: a. Cutting and blanking of aluminum substrate; b. Use a punching machine to mechanically punch holes to form mechanical through holes; c. preparing a film having a size matching that of the aluminum substrate, and constructing film through holes on the film that match the positions of the mechanical through holes; d. Cover the adhesive film on the aluminum substrate to allow the two to bond and align the adhesive film through-holes with the mechanical through-holes; e. Apply epoxy resin to fill the film through-holes and mechanical through-holes; f. After the epoxy resin is cured, tear off the film and grind the board to make the epoxy resin protruding from the mechanical through hole flush with the aluminum substrate; g. Drilling the through holes filled with epoxy resin using a CO2 laser; The mechanical through hole has a burred and rough inner wall.

[0025] Preferably, the diameter of the adhesive film through hole is larger than the diameter of the mechanical through hole.

[0026] Furthermore, the adhesive film is a polyethylene elastic film, and the through holes of the adhesive film are constructed by laser punching. When the adhesive film is punched, the adhesive film is clamped between a pair of heat sinks, and the heat sinks are constructed with through holes for laser to pass through.

[0027] Furthermore, the adhesive film is bonded to the aluminum substrate by a vacuum laminator.

[0028] Furthermore, the thickness of the adhesive film is 0.6 mm to 0.8 mm, and the through hole of the adhesive film is a circular hole.

[0029] Furthermore, when necessary, after completing step b, a rough grinding needle is inserted into the mechanical through hole to form a rough inner wall with burrs.

[0030] Furthermore, in step f, the epoxy resin is cured in a vacuum environment.

[0031] Furthermore, in step g, the focal plane of the CO2 laser is set below the aluminum substrate.

[0032] Furthermore, the CO2 laser is a pulsed laser, and the pulse rate of the CO2 laser is 150 Hz.

[0033] Example 2 A laser drilling method for an aluminum-based PCB board comprises the following steps: a. Cutting and blanking of aluminum substrate; b. Use a punching machine to mechanically punch holes to form mechanical through holes; c. preparing a film having a size matching that of the aluminum substrate, and constructing film through holes on the film that match the positions of the mechanical through holes; d. Cover the adhesive film on the aluminum substrate to allow the two to bond and align the adhesive film through-holes with the mechanical through-holes; e. Apply epoxy resin to fill the film through-holes and mechanical through-holes; f. After the epoxy resin is cured, tear off the film and grind the board to make the epoxy resin protruding from the mechanical through hole flush with the aluminum substrate; g. Drilling the through holes filled with epoxy resin using a CO2 laser; The mechanical through hole has a burred and rough inner wall.

[0034] Preferably, the diameter of the adhesive film through hole is larger than the diameter of the mechanical through hole.

[0035] Furthermore, the adhesive film is a polyethylene elastic film, and the through holes of the adhesive film are constructed by laser punching. When the adhesive film is punched, the adhesive film is clamped between a pair of heat sinks, and the heat sinks are constructed with through holes for laser to pass through.

[0036] Furthermore, the adhesive film is bonded to the aluminum substrate by a vacuum laminator.

[0037] Furthermore, the thickness of the adhesive film is 0.6 mm to 0.8 mm, and the through hole of the adhesive film is a circular hole.

[0038] Furthermore, when necessary, after completing step b, a rough grinding needle is inserted into the mechanical through hole to form a rough inner wall with burrs.

[0039] Furthermore, in step f, the epoxy resin is cured in a vacuum environment.

[0040] Furthermore, in step g, the focal plane of the CO2 laser is set below the aluminum substrate.

[0041] Furthermore, the CO2 laser is a pulsed laser, and the pulse rate of the CO2 laser is 180 Hz.

[0042] Example 3 A laser drilling method for an aluminum-based PCB board comprises the following steps: a. Cutting and blanking of aluminum substrate; b. Use a punching machine to mechanically punch holes to form mechanical through holes; c. preparing a film having a size matching that of the aluminum substrate, and constructing film through holes on the film that match the positions of the mechanical through holes; d. Cover the adhesive film on the aluminum substrate to allow the two to bond and align the adhesive film through-holes with the mechanical through-holes; e. Apply epoxy resin to fill the film through-holes and mechanical through-holes; f. After the epoxy resin is cured, tear off the film and grind the board to make the epoxy resin protruding from the mechanical through hole flush with the aluminum substrate; g. Drilling the through holes filled with epoxy resin using a CO2 laser; The mechanical through hole has a burred and rough inner wall.

[0043] Preferably, the diameter of the adhesive film through hole is larger than the diameter of the mechanical through hole.

[0044] Furthermore, the adhesive film is a polyethylene elastic film, and the through holes of the adhesive film are constructed by laser punching. When the adhesive film is punched, the adhesive film is clamped between a pair of heat sinks, and the heat sinks are constructed with through holes for laser to pass through.

[0045] Furthermore, the adhesive film is bonded to the aluminum substrate by a vacuum laminator.

[0046] Furthermore, the thickness of the adhesive film is 0.6 mm to 0.8 mm, and the through hole of the adhesive film is a circular hole.

[0047] Furthermore, when necessary, after completing step b, a rough grinding needle is inserted into the mechanical through hole to form a rough inner wall with burrs.

[0048] Furthermore, in step f, the epoxy resin is cured in a vacuum environment.

[0049] Furthermore, in step g, the focal plane of the CO2 laser is set below the aluminum substrate.

[0050] Furthermore, the CO2 laser is a pulsed laser, and the pulse rate of the CO2 laser is 200 Hz.

[0051] Thus, for the present application, before using a CO2 laser to drill holes in the aluminum substrate, a mechanical through hole is first drilled on the aluminum substrate using a mechanical drilling device, and the inner wall of the mechanical through hole needs to maintain a large number of burrs and a rough inner wall structure, and then the adhesive film is bonded to the aluminum substrate, and the adhesive film through hole is aligned with the mechanical through hole. After coating the epoxy resin, only the adhesive film through hole and the mechanical through hole are filled with epoxy resin. After the epoxy resin is cured, the adhesive film is torn off, and the epoxy resin protruding from the aluminum substrate is polished, so as to avoid the top surface of the epoxy resin material filled in the mechanical through hole from being concave, resulting in uneven inner wall thickness after subsequent drilling.

[0052] After the epoxy resin is cured, a low-power CO2 laser is used to drill holes. Since the ablation limit of epoxy resin is significantly lower than that of the aluminum substrate, when the epoxy resin in the mechanical through hole is ablated, it will not cause serious carbonization near the mechanical through hole of the aluminum substrate due to excessive energy. In addition, the thermal conductivity of epoxy resin is significantly lower than that of the aluminum substrate itself. Therefore, after the drilling laser contacts the epoxy resin, the heat dissipates more slowly than when it directly contacts the aluminum substrate. Therefore, compared with directly using the laser to act on the aluminum substrate, the power of directly ablating the epoxy resin with the laser can be significantly lower than that of directly ablating the substrate itself, thereby achieving the purpose of drilling holes in the aluminum substrate using a low-power laser.

[0053] Moreover, after the epoxy resin is filled in the mechanical through hole, it can also complement the aluminum substrate. When the through hole is formed in the epoxy resin, the residual heat of the epoxy resin itself can be quickly conducted away by the aluminum substrate, thereby effectively avoiding the problem of the inner wall of the through hole being sagged due to the long-term retention of the residual heat of the epoxy resin after the through hole is formed, resulting in the problem of the inner wall being not smooth.

[0054] At the same time, the burrs and rough inner walls of the mechanical through holes of the present application can improve the bonding between the inner walls of the mechanical through holes and the epoxy resin, and can also simplify the mechanical drilling steps, so that even low-precision mechanical drilling can still meet the requirements, thereby reducing the requirements and costs of factory construction. In addition, there is no need to drill and polish the inner walls of the mechanical through holes, which can also reduce the production process.

[0055] Moreover, by making the diameter of the film through hole larger than the diameter of the mechanical through hole, after the epoxy resin is applied, part of the epoxy resin will cover the aluminum substrate near the two ends of the mechanical through hole. This covered part can well cover the deformed part of the aluminum substrate caused by the formation of the mechanical through hole on the aluminum substrate during the mechanical punching process. Therefore, after the subsequent polishing is completed, the part of the aluminum substrate that is deformed due to the mechanical punching can be coated in the epoxy resin, thereby effectively improving the flatness of the entire aluminum substrate after punching, and avoiding the deformation of the ends of the mechanical through hole on the aluminum substrate and affecting the overall processing performance of the aluminum substrate.

[0056] Therefore, the epoxy resin filled in the mechanical through hole and the epoxy resin covering the deformed part can avoid affecting the coverage of the insulating film due to the deformation of the aluminum substrate when the insulating film is subsequently constructed on the aluminum substrate.

[0057] After laser drilling is completed, the epoxy resin covering the inner wall of the through hole can also act as an insulating film. In this way, in the subsequent insulating film process, even if the insulating film coverage in the hole is poor, it will not affect the normal subsequent copper deposition operation of the aluminum substrate.

[0058] Laser holes are made on the film while it is clamped by a heat sink. Since the film is made of polyethylene elastic film, if mechanical drilling is used, the film is easily entangled, resulting in unevenness of the film part, affecting its coverage with the aluminum substrate.

[0059] If laser drilling is used directly, the film through-holes formed by laser drilling are prone to curling and sagging due to the poor heat dissipation of the film. In addition, the inner wall of the film through-hole is prone to agglomeration due to the melting of the film.

[0060] Therefore, when laser drilling is performed on the film, the film is clamped between a pair of heat sinks, and the laser is allowed to pass through the through holes on the heat sinks and act on the film, thereby forming through holes in the film. The heat sink is used to quickly conduct away the heat remaining on the film, thereby avoiding problems caused by slow heat dissipation during laser drilling of through holes in the film.

[0061] Combined with curing the epoxy resin in a vacuum environment, the bubbles in the epoxy resin can be discharged in large quantities during curing in a vacuum environment. Even some remaining bubbles can be gathered on the surface of the cured epoxy resin and can be removed during the subsequent grinding process. This is also the reason why the aforementioned film is selected to be 0.6mm~0.8mm. Too thick a film will cause the grinding time to be too long.

[0062] Therefore, the drilling method of the present application can not only realize low-cost, low-power laser drilling of the aluminum substrate, but also make the inner wall smooth after the hole is formed, and can also compensate for the deformation of the aluminum substrate caused by mechanical drilling during the drilling process.

[0063] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser drilling method for aluminum-based PCB board, characterized in that: The following steps are involved: a. Cutting and blanking of aluminum substrate; b. Use a punching machine to mechanically punch holes to form mechanical through holes; c. preparing a film having a size matching that of the aluminum substrate, and constructing film through holes on the film that match the positions of the mechanical through holes; d. Cover the adhesive film on the aluminum substrate to allow the two to bond and align the adhesive film through-holes with the mechanical through-holes; e. Apply epoxy resin to fill the film through-holes and mechanical through-holes; f. After the epoxy resin is cured, tear off the film and grind the board to make the epoxy resin protruding from the mechanical through hole flush with the aluminum substrate; g. Drilling the through holes filled with epoxy resin using a CO2 laser; The mechanical through hole has a burred and rough inner wall.

2. The laser drilling method for aluminum-based PCB board according to claim 1, characterized in that: The diameter of the adhesive film through hole is greater than the diameter of the mechanical through hole.

3. The laser drilling method for aluminum-based PCB board according to claim 1, characterized in that: The adhesive film is a polyethylene elastic film, and the through holes of the adhesive film are constructed by laser punching. When the adhesive film is punched, the adhesive film is clamped between a pair of heat sinks, and the heat sinks are constructed with through holes for laser to pass through.

4. The laser drilling method for aluminum-based PCB board according to claim 1, characterized in that: The adhesive film is bonded to the aluminum substrate by a vacuum laminator.

5. The laser drilling method for aluminum-based PCB board according to claim 1, characterized in that: The thickness of the adhesive film is 0.06 mm to 0.08 mm, and the through hole of the adhesive film is a circular channel.

6. The laser drilling method for aluminum-based PCB board according to claim 1, characterized in that: After completing step b, a rough grinding needle is inserted into the mechanical through hole to form a rough inner wall with burrs.

7. The laser drilling method for aluminum-based PCB board according to claim 1, characterized in that: In step f, the epoxy resin is cured in a vacuum environment.

8. The laser drilling method for aluminum-based PCB board according to claim 1, characterized in that: In step g, the focal plane of the CO2 laser is set below the aluminum substrate.

9. The laser drilling method for aluminum-based PCB board according to claim 8, characterized in that: The CO2 laser is a pulsed laser, and the pulse number of the CO2 laser is 150-200 Hz.