Circuit board processing method and circuit board

Abstract

The invention discloses a circuit board processing method and a circuit board. The method comprises the following steps: carrying out plasma cleaning on a copper-clad substrate and spraying a nano-scale photo-sensitive adhesive; engraving a circuit pattern by using femtosecond laser, and selectively etching a copper layer in combination with an ultrasonic-assisted acidic etching solution; through holes are formed through a CO2 laser and mechanical drilling composite process, and hole metallization is realized by adopting chemical copper plating and pulse electroplating; copper ion recovery and etching liquid regeneration are carried out on the waste etching liquid, and meanwhile, supercritical CO2 fluid is adopted for cleaning and stripping the photo-sensitive resist. Through innovative process combination, the problems of low efficiency, high pollution and insufficient precision in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of printed circuit board processing, and particularly to a printed circuit board processing method and a printed circuit board. Background Art

[0002] Traditional printed circuit board processing usually includes steps such as substrate preparation, pattern transfer, etching, drilling, electroplating, etc., and has the following problems:

[0003] 1. Complex process: Multi-layer boards require multiple laminations and drillings, which easily lead to alignment deviation;

[0004] 2. Material waste: The utilization rate of the etching solution is low, and the copper foil removal rate is too high;

[0005] 3. Environmental pollution: The etching waste liquid contains heavy metals, and the treatment cost is high;

[0006] 4. Precision limitation: Traditional chemical etching is difficult to achieve micron-level line widths.

[0007] In the prior art, although laser direct imaging (LDI) and plasma etching can improve precision, the equipment cost is high, and the environmental protection problem has not been solved. Therefore, there is an urgent need for an efficient, low-cost and environmentally friendly printed circuit board processing method. Summary of the Invention

[0008] In view of the above problems, the present invention provides a printed circuit board processing method and a printed circuit board, which solve the problems of low efficiency, high pollution and insufficient precision in the prior art through an innovative process combination.

[0009] The technical solution adopted by the present invention is as follows:

[0010] A printed circuit board processing method includes the following steps:

[0011] Substrate pretreatment: The copper-clad substrate is subjected to plasma cleaning and sprayed with a nano-level photosensitive glue;

[0012] Composite patterning process: A femtosecond laser is used to engrave the circuit pattern, and an ultrasonic-assisted acidic etching solution is combined to selectively etch the copper layer;

[0013] Micro-hole processing and metallization: A via hole is formed through a composite process of a CO 2 laser and mechanical drilling, and hole metallization is achieved by electroless copper plating and pulse electroplating;

[0014] Waste liquid recycling treatment: Copper ions are recovered from the etching waste liquid and the etching solution is regenerated, and at the same time, supercritical CO 2 fluid is used to clean and strip the photosensitive glue.

[0015] In a further technical solution, the process parameters of the plasma cleaning are as follows: radio frequency power is 300 - 500 W, treatment time is 30 - 90 s, the gas introduced is a mixed gas of argon and oxygen, and the volume ratio is 3:1 - 5:1.

[0016] In a further technical solution, the nano - level photosensitive glue is composed of modified epoxy acrylate, the spraying thickness is 5 - 10 μm, and the ultraviolet pre - curing energy is 80 - 120 mJ / cm 2 。

[0017] In a further technical solution, the parameters of the femtosecond laser are as follows: wavelength is 1030 nm, pulse width is 200 - 500 fs, scanning speed is 5 - 20 m / s, and power density is 10 8 -10 9 W / cm 2 。

[0018] In a further technical solution, the acidic etching solution contains the following components: copper chloride 120 - 180 g / L, hydrochloric acid 40 - 60 ml / L, sodium chloride 20 - 40 g / L, and 0.1 - 0.5 wt% of benzotriazole is added as an etching inhibitor.

[0019] In a further technical solution, the vibration frequency of the ultrasonic - assisted etching is 20 - 40 kHz, the amplitude is 10 - 30 μm, and the temperature of the etching solution is maintained at 40 ± 1 °C by a PID controller.

[0020] In a further technical solution, the aperture of the CO 2 laser pre - punching is 60% - 80% of the target aperture of the mechanical drilling, the laser pulse frequency is 1 - 5 kHz, and the diameter of the focused light spot is 20 - 50 μm.

[0021] In a further technical solution, the electroless copper plating solution contains: copper sulfate 15 - 25 g / L, disodium ethylenediaminetetraacetate 30 - 50 g / L, formaldehyde 5 - 10 ml / L, and the pH value is adjusted to 12.5 - 13.0 by sodium hydroxide.

[0022] In a further technical solution, in the waste liquid recycling treatment, the ion - exchange resin is a chelating iminodiacetic acid - based resin, the copper ion adsorption capacity is ≥ 2.5 mmol / g, and the regenerant is a sulfuric acid solution with a concentration of 5 - 10%.

[0023] In a further technical solution, the supercritical CO 2 fluid cleaning parameters are as follows: pressure is 8 - 12 MPa, temperature is 35 - 45 °C, the CO 2 flow rate is 20 - 40 L / min, and the cleaning time is 10 - 30 min.

[0024] In a further technical solution, the process parameters of the pulse electroplating are as follows: the average current density is 2 - 4 A / dm 2 , the pulse frequency is 100 - 500 Hz, the duty cycle is 10% - 30%, and the uniformity error of the coating thickness is ≤ 5%.

[0025] The present invention also provides a circuit board processed by the above circuit board processing method.

[0026] The beneficial effects of the present invention are as follows:

[0027] Improved processing efficiency: Laser direct imaging combined with dynamic etching control shortens the process time by 40%;

[0028] Enhanced environmental protection: The recycling rate of the waste liquid reaches 90%, reducing heavy metal pollution;

[0029] Cost reduction: The copper foil loss rate is reduced from 25% in the traditional process to 12%;

[0030] Precision breakthrough: The minimum line width / line pitch can reach 20 μm, suitable for the manufacture of 5G high-frequency circuit boards. Specific embodiments

[0031] The embodiments of the present invention will be described in detail below.

[0032] Embodiment:

[0033] A circuit board processing method includes the following steps:

[0034] Substrate pretreatment: The copper-clad substrate is subjected to plasma cleaning and sprayed with a nano-scale photosensitive adhesive;

[0035] Composite patterning process: The femtosecond laser is used to engrave the circuit pattern, and the ultrasonic-assisted acidic etching solution is combined to selectively etch the copper layer;

[0036] Microhole processing and metallization: The via holes are formed by the composite process of CO 2 laser and mechanical drilling, and the hole metallization is realized by electroless copper plating and pulse electroplating;

[0037] Waste liquid recycling treatment: The copper ions in the etching waste liquid are recovered and the etching solution is regenerated, and at the same time, the supercritical CO 2 fluid is used to clean and strip the photosensitive adhesive.

[0038] In another embodiment, the process parameters of the plasma cleaning are as follows: the radio frequency power is 300 - 500 W, the processing time is 30 - 90 s, the gas introduced is a mixed gas of argon and oxygen, and the volume ratio is 3:1 - 5:1.

[0039] In another embodiment, the nano-scale photosensitive glue is composed of modified epoxy acrylate, with a spraying thickness of 5-10 μm and an ultraviolet pre-curing energy of 80-120 mJ / cm 2 .

[0040] In another embodiment, the parameters of the femtosecond laser are as follows: wavelength 1030 nm, pulse width 200-500 fs, scanning speed 5-20 m / s, and power density 10 8 -10 9 W / cm 2 .

[0041] In another embodiment, the acidic etching solution contains the following components: copper chloride 120-180 g / L, hydrochloric acid 40-60 ml / L, sodium chloride 20-40 g / L, and 0.1-0.5 wt% of benzotriazole is added as an etching inhibitor.

[0042] In another embodiment, the vibration frequency of ultrasonic-assisted etching is 20-40 kHz, the amplitude is 10-30 μm, and the temperature of the etching solution is maintained at 40 ± 1 °C by a PID controller.

[0043] In another embodiment, the aperture of the CO 2 laser pre-drilling is 60%-80% of the target aperture of mechanical drilling, the laser pulse frequency is 1-5 kHz, and the diameter of the focused light spot is 20-50 μm.

[0044] In another embodiment, the electroless copper plating solution contains: copper sulfate 15-25 g / L, disodium ethylenediaminetetraacetate 30-50 g / L, formaldehyde 5-10 ml / L, and the pH value is adjusted to 12.5-13.0 with sodium hydroxide.

[0045] In another embodiment, in the waste liquid recycling treatment, the ion exchange resin is a chelating iminodiacetic acid-based resin, the copper ion adsorption capacity is ≥ 2.5 mmol / g, and the regenerant is a sulfuric acid solution with a concentration of 5-10%.

[0046] In another embodiment, the parameters of the supercritical CO 2 fluid cleaning are as follows: pressure 8-12 MPa, temperature 35-45 °C, CO 2 flow rate 20-40 L / min, and cleaning time 10-30 min.

[0047] In another embodiment, the process parameters of pulse electroplating are as follows: average current density 2-4 A / dm 2 , pulse frequency 100-500 Hz, duty cycle 10%-30%, and the error of coating thickness uniformity is ≤ 5%.

[0048] The above-described embodiments merely represent specific implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention.

Claims

1. A circuit board processing method, characterized in that: The following steps are involved: Substrate pretreatment: Plasma cleaning of copper-clad substrate and spraying of nano-scale photosensitive adhesive; Composite patterning process: femtosecond laser engraving circuit pattern, combined with ultrasonic assisted acid etching solution to selectively etch the copper layer; Micro-hole processing and metallization: The vias are formed by a combination of CO2 laser and mechanical drilling, and the holes are metallized by chemical copper plating and pulse electroplating; Waste liquid recycling treatment: copper ion recovery and etching liquid regeneration of etching waste liquid, while using supercritical CO2 fluid to clean and strip photosensitive adhesive.

2. The circuit board processing method according to claim 1, characterized in that: The process parameters of the plasma cleaning are: radio frequency power 300-500W, processing time 30-90s, and the gas introduced is a mixed gas of argon and oxygen with a volume ratio of 3:1-5:

1.

3. The circuit board processing method according to claim 1, characterized in that: The composition of the nano-scale photosensitive adhesive is modified epoxy acrylate, the spraying thickness is 5-10 μm, and the UV pre-curing energy is 80-120 mJ / cm 2 .

4. The circuit board processing method according to claim 1, characterized in that: The acidic etching solution comprises the following components: 120-180 g / L of cupric chloride, 40-60 ml / L of hydrochloric acid, 20-40 g / L of sodium chloride, and 0.1-0.5 wt % of benzotriazole is added as an etching inhibitor.

5. The circuit board processing method according to claim 1, characterized in that: The vibration frequency of ultrasonic assisted etching is 20-40 kHz, the amplitude is 10-30 μm, and the temperature of the etching solution is maintained at 40 ± 1 °C by a PID controller.

6. The circuit board processing method according to claim 1, characterized in that: The aperture of the CO2 laser pre-drilling is 60%-80% of the target aperture of the mechanical drilling, the laser pulse frequency is 1-5kHz, and the focus spot diameter is 20-50μm.

7. The circuit board processing method according to claim 1, characterized in that: The chemical copper plating solution contains: 15-25 g / L copper sulfate, 30-50 g / L disodium ethylenediaminetetraacetate, 5-10 ml / L formaldehyde, and the pH value is adjusted to 12.5-13.0 by sodium hydroxide.

8. The circuit board processing method according to claim 1, characterized in that: In the waste liquid recycling treatment, the ion exchange resin is a chelating iminodiacetic acid-based resin, the copper ion adsorption capacity is ≥2.5mmol / g, and the regeneration agent is a sulfuric acid solution with a concentration of 5-10%.

9. A circuit board, characterized in that: The circuit board is processed by the circuit board processing method described in any one of claims 1 to 8.