Method for repairing copper shortage defect of printed circuit board

Abstract

The invention discloses a method for repairing a copper shortage defect of a printed circuit board, which comprises the following steps of: A, carrying out oxidation treatment on the surface of the printed circuit board to form an oxidation protection film on the surface of the printed circuit board; b, determining a copper-deficient defect area on the surface of the printed circuit board, and removing an oxidation protection film and a copper wire in the copper-deficient defect area through laser ablation, so that a base material in the copper-deficient defect area is exposed; c, forming a copper seed layer on the surface of the base material in the copper-less defect area in the step B through laser transfer printing; and D, the printed circuit board in the step C is soaked in an alkaline electroplating solution for electroplating treatment, so that a complete copper wire is generated on the surface of the copper seed layer. The method for repairing the copper shortage defect of the printed circuit board is simple in step and high in operability, low-cost and high-efficiency repairing of the copper shortage defect of the printed circuit board can be effectively achieved, the performance of the printed circuit board cannot be damaged, and the defects in the prior art are overcome.

Description

Technical Field

[0001] The invention relates to the technical field of printed circuit board repair, and in particular to a method for repairing a copper deficiency defect of a printed circuit board. Background Art

[0002] PCB (Printed Circuit Board) is called printed circuit board, also known as printed circuit board, which is an important electronic component, a support for electronic components, and a carrier for the electrical connection of electronic components. Because it is made by electronic printing, it is called a "printed" circuit board.

[0003] Printed circuit boards are mainly composed of insulating substrates, copper wires and pads. They have the dual functions of conductive circuits and insulating base plates. They can replace complex wiring to achieve electrical connections of components in circuits, simplify assembly, welding and other tasks, greatly improve the integration of equipment and reduce the size of equipment. The manufacturing process of printed circuit boards includes major processes such as exposure, development, electroplating and etching. Due to the yield issues of each manufacturing process, the produced printed circuit boards may produce copper defects, including open circuits, local depressions, over-etching, and feature points that are too small. The copper wire height and / or width of the above-mentioned copper defects are generally lower than the design value, so that the local electrical performance of the printed circuit board cannot meet the requirements. Therefore, precise repair of the above-mentioned copper defects is of great significance for improving the manufacturing yield of printed circuit boards.

[0004] In view of the above-mentioned copper deficiency defects, there are reports in the prior art that the copper deficiency defects are repaired by laser transfer printing, but this method requires the use of a nano-thick metal film as a repair material, and the amount of metal produced by a single transfer is extremely small, resulting in extremely high costs and extremely low efficiency for the above-mentioned repair method. There are also methods reported to repair copper deficiency defects by locally coating metal nanoparticles and then sintering at low temperature, but the above-mentioned repair method will introduce a sintering process, which is very likely to damage the insulating substrate performance of the printed circuit board. Summary of the invention

[0005] The purpose of the present invention is to provide a method for repairing a copper deficiency defect in a printed circuit board, which has simple steps and strong operability, can effectively realize low-cost and high-efficiency repair of the copper deficiency defect in the printed circuit board, and will not cause damage to the performance of the printed circuit board, thereby overcoming the shortcomings of the prior art.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A method for repairing a copper deficiency defect of a printed circuit board, wherein the printed circuit board comprises a substrate and copper wires arranged on a surface of the substrate, and the repair method comprises the following steps:

[0008] A. performing oxidation treatment on the surface of the printed circuit board to form an oxide protective film on the surface of the copper wire on the printed circuit board;

[0009] B. determining a copper deficiency defect area on the surface of the printed circuit board, and removing the oxide protective film and copper wire in the copper deficiency defect area by laser ablation to expose the substrate in the copper deficiency defect area;

[0010] C. Forming a copper seed layer on the surface of the substrate in the copper-poor defective area in step B by laser transfer;

[0011] D. Immersing the printed circuit board of step C in an alkaline electroplating solution for electroplating, so that complete copper wires are generated on the surface of the copper seed layer.

[0012] Preferably, step E is further included, and step E is located between step C and step D;

[0013] E. Removing copper particles outside the copper-deficient defect region by laser ablation.

[0014] Preferably, in step A, the conductivity of the oxide protection film is less than 20% of the conductivity of the copper wire.

[0015] Preferably, the thickness of the copper seed layer does not exceed 30% of the designed thickness of the copper wire.

[0016] Preferably, in step A, the specific step of the oxidation treatment is: immersing the printed circuit board in an oxidizing solution.

[0017] The technical solution provided by the present invention may include the following beneficial effects:

[0018] The present invention proposes a method for repairing a copper deficiency defect on a printed circuit board, which has simple steps and strong operability, and can effectively realize low-cost and high-efficiency repair of copper deficiency defects on a printed circuit board without causing damage to the performance of the printed circuit board, thus overcoming the shortcomings of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a schematic flow chart of a method for repairing a copper deficiency defect of a printed circuit board.

[0020] Figure 2 It is a schematic diagram of the copper deficiency defect in Example 1 of the present invention.

[0021] Figure 3 It is a schematic diagram of the copper deficiency defect in Example 2 of the present invention. DETAILED DESCRIPTION

[0022] A method for repairing a copper deficiency defect of a printed circuit board, wherein the printed circuit board comprises a substrate and copper wires arranged on a surface of the substrate, and the repair method comprises the following steps:

[0023] A. performing oxidation treatment on the surface of the printed circuit board to form an oxide protective film on the surface of the copper wire on the printed circuit board;

[0024] B. determining a copper deficiency defect area on the surface of the printed circuit board, and removing the oxide protective film and copper wire in the copper deficiency defect area by laser ablation to expose the substrate in the copper deficiency defect area;

[0025] C. Forming a copper seed layer on the surface of the substrate in the copper-poor defective area in step B by laser transfer;

[0026] D. Immersing the printed circuit board of step C in an alkaline electroplating solution for electroplating, so that complete copper wires are generated on the surface of the copper seed layer.

[0027] In order to achieve low-cost and high-efficiency repair of copper deficiency defects in printed circuit boards, this technical solution proposes a method for repairing copper deficiency defects in printed circuit boards, and its flow chart is as follows: Figure 1 As shown, it includes four steps: A (oxidation), B (ablation), C (transfer) and D (electroplating).

[0028] Specifically, the present solution first requires oxidation treatment of the surface of the printed circuit board to be repaired to form an oxide protective film on the surface of its copper wires. Since the substantial component of the oxide protective film is mainly copper oxide, i.e., copper oxide and / or cuprous oxide, and the protective film of the above components has a low conductivity, the copper wires located outside the copper-poor defective area (i.e., the "non-defective area") can be protected during the electroplating process of the subsequent step D, preventing the growth of excess copper wires in the non-defective area, causing the copper wires of the printed circuit board to deviate from the original design.

[0029] Then, this scheme determines the copper-poor defect area on the surface of the printed circuit board, and removes the oxide protective film and copper wire in the copper-poor defect area by laser ablation, so that the substrate in the copper-poor defect area is exposed, so as to obtain a flat growth surface, so that the copper wire after electroplating has growth consistency, so as to ensure the overall electrical performance of the printed circuit board. In addition, the exposed substrate generally has a rougher surface, which is also conducive to improving the adhesion of the copper seed layer on the substrate surface in step C, thereby ensuring the bonding between the repaired copper wire structure and the substrate.

[0030] Since the substrate in this solution refers to the dielectric layer that carries the copper wire in the printed circuit board, which is generally a polymer composite material or a ceramic material, in order to make the copper ions in the plating solution grow in the desired defect area during the electroplating process, this solution also forms a copper seed layer on the surface of the substrate in the copper-poor defect area by laser transfer to increase its conductivity.

[0031] Finally, a complete copper wire structure is directly deposited on the surface of the copper seed layer by electroplating to complete the repair of the copper deficiency defect. It should be noted that in the electroplating process, this solution limits the use of an alkaline electroplating solution (containing copper ions), which can effectively ensure that the oxide protective film is not destroyed during the electroplating process and achieve directional growth of the copper wire structure.

[0032] It should be noted that in step A, the oxide protective film may be formed to partially cover or fully cover the copper wire surface of the printed circuit board, which is not limited here. After the repair is completed, the oxide protective film on the surface of the defect-free area may be removed depending on the subsequent preparation process requirements.

[0033] In step B, the determination of the copper deficiency defect area can be achieved by manual marking or visual inspection, etc., which is not limited here. The laser ablation in step B refers to scanning the copper deficiency defect area with a focused laser beam, and removing the material in the copper deficiency defect area by utilizing the thermal and mechanical effects after the material absorbs the laser energy. The specific laser ablation parameters can be adjusted according to the actual growth of the oxide protection film and the copper wire structure in the copper deficiency defect area.

[0034] In step C, laser transfer refers to using a focused laser beam to irradiate a solid metal (or alloy) coating attached to a transparent substrate, so that the local coating is transferred to a designated position to form a thin layer and / or a bulk structure at the designated position.

[0035] Further, step E is included, and step E is located between step C and step D;

[0036] E. Removing copper particles outside the copper-deficient defect region by laser ablation.

[0037] In step C of this solution, extra copper particles may be transferred outside the copper-poor defective area (i.e., the "defect-free area"), and the above copper particles will grow unnecessary copper wire structures during the electroplating process of step D. Therefore, in order to further ensure that the copper wire structure of the repaired printed circuit board matches the original design, this solution also adds a secondary laser ablation process in step C before the electroplating process to remove the extra copper particles generated in the defect-free area due to laser transfer.

[0038] It should be noted that the laser ablation in step E refers to scanning the copper-deficient defect area with a focused laser beam, and utilizing the thermal and mechanical effects after the material absorbs the laser energy to remove excess copper particles in the defect-free area. The specific laser ablation parameters can be adjusted accordingly according to the actual transfer conditions of the excess copper particles.

[0039] To further illustrate, in step A, the conductivity of the oxide protection film is less than 20% of the conductivity of the copper wire.

[0040] In order to further ensure the protective effect of the oxide protective film during the electroplating process, this solution also optimizes the conductivity of the oxide protective film.

[0041] To further illustrate, the thickness of the copper seed layer does not exceed 30% of the designed thickness of the copper wire.

[0042] In addition, this solution also optimizes the transfer thickness of the copper seed layer. Since the transfer amount of a single laser transfer is very small, if the thickness of the copper seed layer is too high, the transfer efficiency will be reduced and the repair cost will be increased. Moreover, the internal quality of the copper seed layer formed by laser transfer is generally poor. If the proportion of the copper seed layer in the copper wire structure is too large, it may affect the performance of the copper wire structure, which is not conducive to ensuring the repair quality of the printed circuit board.

[0043] To further illustrate, in step A, the specific steps of the oxidation treatment are: immersing the printed circuit board in an oxidizing solution.

[0044] In a preferred embodiment of the present technical solution, the printed circuit board can be immersed in an oxidizing liquid to quickly and easily achieve oxidation treatment of the printed circuit board. In some embodiments, the oxidizing liquid can be a commercially available browning liquid, which is not limited here.

[0045] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0046] Example 1

[0047] Will be like Figure 2 The copper deficiency defect shown is repaired into a copper wire structure with a thickness of 100 μm. The outline of the copper deficiency defect contains only a layer of copper wire with a thickness of 10 μm, which is an over-etching defect.

[0048] A. Immersing a printed circuit board in an aqueous solution of alkaline sodium chlorite for oxidation treatment, so that an oxide protective film is formed on the surface of the copper wire on the printed circuit board; wherein the aqueous solution of alkaline sodium chlorite includes 30 g / L of sodium chlorite, 50 g / L of sodium hydroxide and 100 g / L of trisodium phosphate, the components of the oxide protective film include cuprous oxide and cupric oxide, the thickness of the oxide protective film is 5 μm, and the conductivity is less than 5% of the conductivity of the copper wire.

[0049] B. Determine the copper deficiency defect area on the surface of the printed circuit board, and remove the oxide protective film and copper wire in the copper deficiency defect area by laser ablation to expose the substrate in the copper deficiency defect area; wherein the pulse width of the laser beam used for laser ablation is 10ns, the focused spot is 20μm, the wavelength is 532nm, and multiple grating scans with a spacing of 5μm are performed on the surface of the copper deficiency defect area.

[0050] C. A copper seed layer is formed on the surface of the substrate in the copper-poor defective area in step B by laser transfer; wherein the pulse width of the laser beam used for laser transfer is 1.5ns, the focused spot is 20μm, the wavelength is 532nm, and the laser beam irradiates the solid coating attached to the quartz glass (the thickness of the quartz glass is 1mm, and the solid coating is a copper coating with a thickness of 800nm ​​prepared by electron beam evaporation), and the coating is partially melted and transferred to the copper-poor defective area. Through multiple transfer and accumulation, five layers of copper seed layers formed by the closely stacked arrangement of the transferred particles are formed, and the thickness of the copper seed layer is 4μm.

[0051] E. Remove copper particles outside the copper deficiency defect area by laser ablation; wherein the pulse width of the laser beam used for laser ablation is 10ns, the focused spot is 20μm, the wavelength is 532nm, and irradiation or scanning is performed outside the copper deficiency defect area.

[0052] D. Immerse the printed circuit board in step C in an alkaline electroplating solution for electroplating, so that a complete copper wire is formed on the surface of the copper seed layer; wherein the alkaline electroplating solution includes 75 g / L CuCN, 100 g / L NaCN and 30 g / L NaOH, the reaction temperature of the electroplating treatment is 70°C, and the current is 1-10 A / dm 2 .

[0053] Example 2

[0054] Will be like Figure 3 The copper deficiency defect shown is repaired into a copper wire structure with a thickness of 30 μm. The copper wire thickness within the outline of the copper deficiency defect is uneven, which is a local concave defect.

[0055] A. Immerse the printed circuit board in a commercially available browning solution (DY-303 browning solution produced by Guangzhou Dayang Chemical Technology) for oxidation treatment to form an oxide protective film on the surface of the printed circuit board; wherein the components of the oxide protective film include cuprous oxide, cupric oxide and organic copper compounds, the thickness of the oxide protective film is 7 μm, and the conductivity is less than 10% of the conductivity of the copper wire.

[0056] B. Determine the copper deficiency defect area on the surface of the printed circuit board, and remove the oxide protective film and copper wire in the copper deficiency defect area by laser ablation to expose the substrate in the copper deficiency defect area; wherein the pulse width of the laser beam used for laser ablation is 2ns, the focused spot is 20μm, the wavelength is 532nm, and multiple grating scans with a spacing of 3μm are performed on the surface of the copper deficiency defect area.

[0057] C. By laser transfer, a copper seed layer is formed on the surface of the substrate in the copper-poor defective area in step B; wherein the pulse width of the laser beam used for laser transfer is 2ns, the focused spot is 20μm, the wavelength is 532nm, and the laser beam irradiates the solid coating attached to the quartz glass (the thickness of the quartz glass is 1mm, the solid coating is a copper alloy coating with a thickness of 1000nm prepared by electron beam evaporation, and the copper alloy coating includes 99wt% of copper and 1wt% of chromium), and the coating is partially melted and transferred to the copper-poor defective area. Through multiple transfer and accumulation, eight layers of copper seed layers formed by the closely stacked arrangement of the transferred particles are formed, and the thickness of the copper seed layer is 6μm.

[0058] E. Remove copper particles outside the copper deficiency defect area by laser ablation; wherein the pulse width of the laser beam used for laser ablation is 2ns, the focused spot is 20μm, the wavelength is 532nm, and irradiation or scanning is performed outside the copper deficiency defect area.

[0059] D. Immerse the printed circuit board in step C in an alkaline electroplating solution for electroplating, so that a complete copper wire is formed on the surface of the copper seed layer; wherein the alkaline electroplating solution includes 45 g / L CuCN, 56 g / L NaCN and 30 g / L Na2CO3, the reaction temperature of the electroplating treatment is 60°C, and the current is 1.5-6 A / dm 2 .

[0060] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the scope of protection of the present invention.

Claims

1. A method for repairing a copper deficiency defect in a printed circuit board, characterized in that: The printed circuit board comprises a substrate and copper wires arranged on the surface of the substrate, and the repair method comprises the following steps: A. performing oxidation treatment on the surface of the printed circuit board to form an oxide protective film on the surface of the copper wire on the printed circuit board; B. determining a copper deficiency defect area on the surface of the printed circuit board, and removing the oxide protective film and copper wire in the copper deficiency defect area by laser ablation to expose the substrate in the copper deficiency defect area; C. Forming a copper seed layer on the surface of the substrate in the copper-poor defective area in step B by laser transfer; D. Immersing the printed circuit board of step C in an alkaline electroplating solution for electroplating, so that complete copper wires are generated on the surface of the copper seed layer.

2. A method for repairing a copper deficiency defect in a printed circuit board according to claim 1, characterized in that: The method further comprises a step E, wherein the step E is located between the step C and the step D; E. Removing copper particles outside the copper-deficient defect region by laser ablation.

3. A method for repairing a copper deficiency defect in a printed circuit board according to claim 1, characterized in that: In step A, the conductivity of the oxide protection film is less than 20% of the conductivity of the copper wire.

4. A method for repairing a copper deficiency defect in a printed circuit board according to claim 1, characterized in that: The thickness of the copper seed layer does not exceed 30% of the designed thickness of the copper wire.

5. The method for repairing a copper deficiency defect in a printed circuit board according to claim 1, characterized in that: In step A, the specific steps of the oxidation treatment are: immersing the printed circuit board in an oxidizing solution.

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