CN116162976A

CN116162976A - Additive for micro roughening treatment of ultra-low profile copper foil and application method of additive

Info

Publication number: CN116162976A
Application number: CN202310032628.9A
Authority: CN
Inventors: 白忠波; 肖妍; 杜良良; 刘二勇; 孙万昌; 蔡辉; 彭肖林; 冯宝鑫
Original assignee: Xian University of Science and Technology; Lingbao Wason Copper Foil Co Ltd
Current assignee: Xian University of Science and Technology; Lingbao Wason Copper Foil Co Ltd
Priority date: 2023-01-10
Filing date: 2023-01-10
Publication date: 2023-05-26

Abstract

The invention relates to an additive for micro roughening treatment of an ultralow-profile copper foil and a use method thereof. The additive is formed by any combination of one or two or more of titanium sulfite, thiazolinyl dithiopropane sodium sulfonate (SH 110) and fatty amine polyoxyethylene ether (AEO); the use method is that the used additive is added into the copper sulfate base roughening solution, so that the treated copper foil has low roughness and maintains high peel strength when being bonded with a substrate such as resin, and the like, can be used for a high-frequency circuit board, and effectively reduces signal loss.

Description

Additive for micro roughening treatment of ultra-low profile copper foil and application method of additive

Technical Field

The invention belongs to the technical field of electrolytic copper foil, and particularly relates to an additive for micro roughening treatment of an ultralow-profile copper foil and a use method of the additive.

Background

In recent years, the rapid development of 5G means that the era of intelligent interconnection of everything is coming, and the high-frequency and high-speed demands of mobile communication terminals are becoming apparent. Printed circuit boards are also facing more urgent demands in the high-frequency and high-speed age as materials for mounting chips and semiconductor components. Electrolytic copper foil, which is one of the three major components of copper-clad boards for PCBs, is called a "communication neural network", and is also subject to stricter requirements. Therefore, the development of high-frequency and high-speed copper foil materials with higher performance has become an extremely important research topic for copper foil manufacturers worldwide.

For high frequency and high speed PCB circuits, the resistance becomes large at high frequency and most of the current is concentrated on the surface of the circuit, which is the "skin effect" of the conductor. The higher the frequency, the shallower the skin depth. The skin depth is 2 μm at 1GHz, and is only 0.66 μm at 10GHz, so that serious signal standing waves, reflection and the like are necessarily generated when signals are transmitted in a rough layer, and serious signal loss and even complete distortion are caused. The surface roughness of the copper foil has a great influence on the transmission of high-frequency signals. The roughness of ultra low profile (HVLP) copper foil is very low. The HVLP copper foil can provide excellent signal transmission performance in a high frequency state. However, such copper foil has such a low roughness that its adhesion to the resin substrate in the circuit board is poor. Therefore, when the copper foil is processed, the roughening treatment is specially carried out, however, the signal transmission of the high-frequency circuit board is affected to a certain extent after the roughening treatment, and the two contradictions must be coordinated, so that the high-frequency and high-speed signal transmission on the copper foil can be greatly exerted. In order to meet this requirement, the roughened layer on the copper foil must be uniform and as small as possible.

The prior HVLP copper foil roughening step has the following defects: 1. the roughness of part of the processing surface can only reach about 3.5 and um, when the signal transmission frequency reaches more than 10GHz, the loss is larger and even the distortion is high, and the requirements cannot be met; 2. the other part has roughness below 2 um, but the surface is not uniform enough, and the adhesive force between the other part and the substrate can not meet the requirement when the substrate is used in a high-frequency high-speed circuit board.

Disclosure of Invention

Based on the above, the invention aims to solve the problems of the HVLP copper foil for the low-frequency high-speed copper-clad plate, and provides an additive for micro roughening treatment of an ultra-low profile (HVLP) copper foil and a use method thereof, wherein the roughened layer of the copper foil treated by the additive has fine and uniform grains, and achieves the effect of microcrystal.

In order to achieve the above object, the present invention is achieved by:

an additive for micro roughening treatment of ultra-low profile copper foil is composed of one or two or more of titanium sulfite, thiazolinyl dithiopropane sodium sulfonate (SH 110) and fatty amine polyoxyethylene ether (AEO).

Preferably, the additive consists of titanium sulfite, thiazolinyl dithiopropane sodium sulfonate (SH 110) and fatty amine polyoxyethylene ether (AEO), and the addition amount (namely the concentration in the basic roughening liquid) is 1-9 mg/L, 10-40 mg/L and 1-11 mg/L respectively.

Preferably, the addition amounts (i.e. the concentration in the basic roughening solution) of the titanium sulfite, the thiazolinyl dithiopropane sodium sulfonate (SH 110) and the fatty amine polyoxyethylene ether (AEO) are 7 mg/L, 20 mg/L and 5 mg/L respectively.

The application method of the additive for micro roughening treatment of the ultra-low profile copper foil comprises the following specific implementation steps:

(1) Immersing the raw foil into sulfuric acid solution for pickling;

(2) Washing the surface of the raw foil subjected to the acid washing in the step (1) with water, and placing the washed raw foil in a roughening groove;

(3) Adding the additive into the basic roughening liquid in the roughening tank, and electroplating;

(4) And (3) carrying out surface flushing on the copper foil obtained in the step (3) by using deionized water, and placing the copper foil in an oven for drying after cleaning.

Preferably, the basic roughening liquid in the step (3) is prepared from 80-110 g/L H ₂ SO ₄ And 10 to 20 g/L Cu ²⁺ Composition is prepared.

Preferably, the sulfuric acid solution in the step (1) is a 10wt% sulfuric acid solution, and the pickling time is 5-15 s.

Preferably, the electroplating process of step (3) is as follows: the titanium iridium plate is used as an anode, the copper foil is used as a cathode, the temperature is 20-50 ℃, and the current density is 10-50A/dm ² Electrodeposition time is 2-10 s.

Preferably, the step (3) adds the additive into the basic roughening liquid, and the specific method is as follows: the used additives are respectively dissolved and evenly stirred by deionized water at room temperature, and are simultaneously added into the basic roughening liquid by a metering device at a speed of 2-4L per hour.

Preferably, the copper foil obtained in the step (4) has a surface roughness Rz of 1.3-2 μm and a peel strength of 0.4-0.6N/mm.

Wherein, the fatty amine polyoxyethylene ether (AEO) has stable chemical property, higher cloud point, difficult precipitation in high-temperature solution to reduce concentration, and proper proportion of hydrophilic structure and hydrophobic structure in the molecular structure to ensure that the fatty amine polyoxyethylene ether has enough surface activity. In addition, AEO has a sufficiently wide adsorption potential, adsorbs on the electrode surface over a large potential range, and can be used for ideal copper plating additives. After a large number of experiments and data analysis, the invention determines that the addition amount of AEO in the roughening liquid is optimal to be 1-11 mg/L. The effect of refining the grains is not obvious when the content is too low; the too high content can cause the agglomeration phenomenon of the coarsened layer copper particles, and the surface roughness of the copper foil is increased.

The titanium sulfite has stronger deep plating capability, can promote the deposition of copper grains in a low current density area on the copper foil, reduce the peak height of the surface of the copper foil, and promote the valley bottom to obtain a more uniform roughened layer, thereby reducing the surface roughness of the copper foil. After a large number of experiments and data analysis, the invention determines that the addition amount of the titanium sulfite in the roughening liquid is optimal to be 1-9 mg/L. Too high a content of titanium sulphite will cause the copper particles to form independent particle sites and be larger in size.

Sodium thiazolinyl dithiopropane sulfonate (SH 110) has an accelerating effect on the copper deposition process. SH110 is broken down into MPS and H1 by disulfide bonds, and the broken down portions combine with cuprous ions to form Cu-S-propane-sulfonate and thiazolinyl-S-Cu, which act as accelerators and suppressors, respectively. H1 adsorbs on the cathode surface active site, thereby preventing deposition of copper ions on the protruding parts of the cathode. And the promotion part MPS is adsorbed on the surface of the cathode copper foil by utilizing sulfhydryl groups, free copper ions in the electrolyte are captured by the sulfonate at the tail end, and then a synergistic effect is generated with chloride ions adsorbed on the surface of the cathode, so that electrons are transferred to the captured copper ions through an electron bridge, and the electrochemical reduction rate of the copper ions in the concave part is greatly improved. Wherein MPS and H1 are in competitive adsorption, and H1 is adsorbed more rapidly than MPS. After a large number of experiments and data analysis, the invention determines that the addition amount of SH110 in the roughening liquid is optimal to be 10-40 mg/L. The concentration is too high, the adsorption amount of SH110 on the cathode is increased, so that local deposition reaction is too fast, copper grains are promoted to be uneven, and roughness is increased.

The invention has the beneficial effects that: the HVLP copper foil roughening additive for the high-frequency high-speed copper-clad plate and the use method thereof can solve the problem that the high-frequency high-speed copper foil has low surface roughness and can not have good bonding capability with a resin substrate, thereby achieving the purposes of low surface roughness, high peel strength and remarkably reducing signal loss in the transmission process of a circuit board of the treated HVLP copper foil for the high-frequency high-speed copper-clad plate.

Drawings

FIG. 1 is a technical roadmap of the invention;

FIG. 2 is a 10000-fold and 20000-fold FESEM pictures of the treated surface of HVLP copper foil for a high-frequency high-speed copper-clad plate prepared in comparative example 1 of the present invention;

FIG. 3 is a 10000-fold and 20000-fold FESEM pictures of the treated surface of HVLP copper foil for a high-frequency and high-speed copper-clad plate prepared in example 1 of the present invention;

FIG. 4 is a 10000-fold and 20000-fold FESEM pictures of the treated surface of HVLP copper foil for a high-frequency and high-speed copper-clad plate prepared in example 2 of the present invention;

FIG. 5 is a 10000-fold and 20000-fold FESEM pictures of the treated surface of HVLP copper foil for a high-frequency and high-speed copper-clad plate prepared in example 3 of the present invention;

fig. 6 is 10000-fold and 20000-fold FESEM pictures of the treated surface of HVLP copper foil for a high-frequency and high-speed copper-clad plate prepared in example 4 of the present invention.

Detailed Description

The present invention will be further described with reference to the following examples, which are intended to be illustrative only and not to be limiting of the invention, and all other examples, which may be made by those of ordinary skill in the art based on the examples herein without the benefit of the teachings herein, are intended to be within the scope of the invention.

The following common experimental conditions of 10 μm untreated battery foil were used for 1 comparative example and 4 examples.

Comparative example 1

The HVLP copper foil micro roughening treatment process for the high-frequency high-speed copper clad laminate comprises the following steps of:

(1) The green foil is first immersed in 10wt% H ₂ SO ₄ Pickling 10 s in the solution, and removing an oxide layer on the surface of the green foil;

(2) Washing the surface of the copper foil with a large amount of deionized water after pickling to remove pickling solution remained on the surface, and placing the copper foil with the cleaned surface in a roughening groove;

(3) Electroplating and roughening grooveIn the method, the electrode spacing between the anode titanium iridium-plated plate and the cathode copper foil is 5 mm, the temperature is 30 ℃, and the current density is 20A/dm ² The electroplating time of the copper foil in the roughening tank is 7 s, and the technological index of the electroplating solution in the roughening tank is shown in Table 1:

TABLE 1

Project	Control range
		Cu ²⁺ (g/L)	12±2
H ₂ SO ₄ (g/L)	100±5

(4) After the copper foil is electroplated in the roughening groove, a large amount of deionized water is used for surface flushing to remove electrolyte remained on the surface, the surface of the copper foil is cleaned, and then the copper foil is placed in an oven for drying, and the roughening treatment is finished.

The results of the performance test after roughening treatment of the comparative example are as follows: peel strength: 0.215 N/mm; the surface roughness Rz was measured at 5 different positions of the roughened surface to obtain an average value: 1.91 μm; as shown in FIG. 2, the roughened surface FESEM has a rough surface structure, uneven copper dot arrangement, more electrons received by the raised surface due to the tip discharge effect, higher current density, and Cu in FIG. 2 ²⁺ The reduction rate is faster, the phenomenon of multi-layer superposition of spherical tumor point particles occurs, and the copper particles have the agglomeration phenomenon; from the comparative example, it can be seen that the coarsened crystals of the copper foil coarsened in the base electrolyte are coarser, and the copper nodule particles of the coarsened layer are not uniform, resulting in lower peel strength and large surface roughness.

Example 1

The difference from comparative example 1 is that: the embodiment adopts a coarsening process with fatty amine polyoxyethylene ether (AEO) as an additive,

the technical scheme and the electrodeposition device are shown in fig. 1, and the steps are as follows:

(1) The raw foil is immersed in 10wt% H ₂ SO ₄ Pickling 10 s in the solution, and removing an oxide layer on the surface of the green foil;

(3) Adding the additive into the basic roughening solution, dissolving fatty amine polyoxyethylene ether (AEO) with deionized water at room temperature, stirring to obtain 10g/L fatty amine polyoxyethylene ether (AEO) solution, dripping into the basic roughening solution at a rate of 2L per hour with a metering device, electroplating, and maintaining the electrode spacing between the anode titanium iridium plate and the cathode copper foil in the roughening tank at 5 mm and 20 deg.C and current density at 20A/dm ² The electroplating time of the copper foil in the roughening tank is 4s, and the technological index of the electroplating solution in the roughening tank is shown in Table 2:

TABLE 2

Project	Control range
		Cu ²⁺ (g/L)	12±2
H ₂ SO ₄ (g/L)	100±5
		AEO (mg/L)	5

The performance test results after roughening treatment in this embodiment are as follows: peel strength: 0.255 N/mm; the surface roughness Rz was measured at 5 different positions of the roughened surface to obtain an average value: 1.51 μm; the morphology of the roughened surface FESEM is shown in FIG. 3, and as can be seen from FIG. 3, the copper particles of the roughened layer of the copper foil are tightly connected. AEO generates characteristic adsorption on the electrode surface to cover the electrolytic surface, thereby Cu near the electrode surface ²⁺ The concentration is reduced, the reaction rate of reducing copper is slowed down, the grain growth process is inhibited, and the purpose of grain refinement is achieved. In addition, it can be seen from the 20000-fold enlarged view of the surface morphology, that the addition of AEO did not change the morphology of the copper particles.

Example 2

The difference from comparative example 1 is that: in this embodiment, a roughening process using titanium sulfite as an additive is shown in fig. 1, and the steps of the process are as follows:

(3) Adding the additive into the basic roughening solution, dissolving titanium sulfite with deionized water at room temperature, stirring to obtain titanium sulfite solution with concentration of 10g/L, dripping into the basic roughening solution at a speed of 3L per hour by using a metering device, electroplating, and placing into a roughening tank, wherein the electrode spacing between the anode titanium iridium plate and the cathode copper foil is 5 mm, the temperature is 40 ℃, and the current density is 10A/dm ² The electroplating time of the copper foil in the roughening tank is 2 s, and the technological index of the electroplating solution in the roughening tank is shown in Table 3:

TABLE 3 Table 3

Project	Control range
		Cu ²⁺ (g/L)	12±2
H ₂ SO ₄ (g/L)	100±5
		Titanium sulfite (mg/L)	7

The performance test results after roughening treatment in this embodiment are as follows: peel strength: 0.495 N/mm; the surface roughness Rz was measured at 5 different positions of the roughened surface to obtain an average value: 1.62 μm; as shown in FIG. 4, the roughened surface FESEM morphology is shown in FIG. 4, and compared with the roughened surface morphology of comparative example 1, the roughened surface FESEM morphology of example 2 is more uniform and compact, and the flatness and compactness of the electroplated copper layer can be effectively improved by adding a proper amount of titanium sulfite into the plating solution. The nucleation number density of the coarsened layer tumor point particles is increased by the titanium sulfite, the cathode polarization and the plating solution dispersion capacity can be increased, the growth speed of crystal nuclei can be slowed down, the electrodeposition surface energy is reduced, the nucleation points of copper on the cathode are increased, the nucleation is easier, the crystal nuclei are more uniform, and the abnormal growth of the copper tumor point particles is reduced. In addition, from the 20000-fold enlarged morphology, it was observed that the addition of titanium sulfite changed the morphology of the copper nodule particles from a smooth spherical shape to a wolf tooth shape.

Example 3

The difference from comparative example 1 is that: in this embodiment, the roughening process using sodium thiazolinyl dithiopropane sulfonate (SH 110) as an additive has the following steps, as shown in FIG. 1:

(3) Adding the additive into the basic roughening solution, dissolving and stirring the thiazolinyl dithiopropane sodium sulfonate (SH 110) with deionized water at room temperature to obtain a thiazolinyl dithiopropane sodium sulfonate (SH 110) solution with the concentration of 10g/L, dripping the thiazolinyl dithiopropane sodium sulfonate (SH 110) into the basic roughening solution at the speed of 3L per hour by using a metering device, electroplating in a roughening tank, wherein the electrode spacing between an anode titanium iridium plate and a cathode copper foil is 5 mm, the temperature is 50 ℃, and the current density is 50A/dm ² The electroplating time of the copper foil in the roughening tank is 10 s, and the process index of the electroplating solution in the roughening tank is shown in Table 4:

TABLE 4 Table 4

Project	Control range
		Cu ²⁺ (g/L)	12±2
H ₂ SO ₄ (g/L)	100±5
		SH110 (mg/L)	20

The performance test results after roughening treatment in this embodiment are as follows: peel strength: 0.505 N/mm; the surface roughness Rz was measured at 5 different positions of the roughened surface to obtain an average value: 1.57 μm; as shown in FIG. 5, SH110 can promote lateral growth of copper grains, and the roughened grains grow into a cauliflower-shaped structure, and the surface tends to be compact as shown in FIG. 5. SH110 has a promoting effect on the copper deposition process, and can decompose accelerator fragments in the solution to promote electron conduction to Cu ²⁺ Thereby promoting Cu ²⁺ And the deposition rate of Cu is improved. However, when SH110 is further added to the solution, local deposition reactions are caused to be too fast, causing copper grain non-uniformity.

Example 4

The difference from comparative example 1 is that: in the embodiment, a roughening process adopting titanium sulfite, thiazolinyl dithiopropane sodium sulfonate (SH 110) and fatty amine polyoxyethylene ether (AEO) as combined additives is adopted, and a technical scheme and an electrodeposition device are shown in fig. 1, and the steps are as follows:

(3) Adding the additive into the basic roughening solution, respectively dissolving titanium sulfite, thiazolinyl dithiopropane sodium sulfonate (SH 110) and fatty amine polyoxyethylene ether (AEO) with deionized water at room temperature, and stirring uniformly to obtain titanium sulfite and thiazolinyl dithiopropyl sulfate with concentration of 10g/LThree solutions of sodium alkane sulfonate (SH 110) and fatty amine polyoxyethylene ether (AEO) are simultaneously added into a basic roughening solution by a metering device at the speed of 4L per hour, and then the three solutions are electroplated, and in a roughening groove, the electrode spacing between an anode titanium iridium plate and a cathode copper foil is 5 mm, the temperature is 30 ℃, and the current density is 40A/dm ² The electroplating time of the copper foil in the roughening tank is 8s, and the technological index of the electroplating solution in the roughening tank is shown in Table 5:

TABLE 5

Project	Control range
		Cu ²⁺ (g/L)	12±2
H ₂ SO ₄ (g/L)	100±5
		SH110 (mg/L)	20
Titanium sulfite (mg/L)	7
		AEO (mg/L)	5

The performance test results after roughening treatment in this embodiment are as follows:

peel strength: 0.598 N/mm; the surface roughness Rz was measured at 5 different positions of the roughened surface to obtain an average value: 1.50 μm; as shown in FIG. 6, the roughened surface FESEM morphology is shown, and as can be seen from FIG. 6, the copper grains generated in the SH110, titanium sulfite and AEO additive system exhibit a large number of uniformly dense distributed and contoured cauliflower-like protrusions, and the composite additive system has a more compact copper grain distribution than the more dispersed copper grain arrangement when a single additive is introduced. This is advantageous in increasing the contact area of the copper foil with the resin substrate, thereby improving the peel strength of the copper foil.

The results of comparing the ultra low profile copper foil samples treated in examples 1-4 of the present invention with comparative example 1 are shown in Table 6:

TABLE 6

	Comparative example 1	Example 1	Example 2	Example 3	Example 4
						Peel strength (N/mm)	0.215	0.255	0.495	0.505	0.598
R _z Value (μm)	1.91	1.51	1.62	1.57	1.50

As is clear from Table 6, the additives of examples 1-4 have a certain effect on reducing roughness and improving peel strength, and the strengthening effect of the composite additive of example 4 is most remarkable because the composite additive can act at different positions on the cathode surface during electrodeposition, thereby improving the morphology and performance of the roughened layer of the copper foil.

Claims

1. An additive for micro roughening treatment of ultra-low profile copper foil is characterized by comprising any combination of one or two or more of titanium sulfite, thiazolinyl dithiopropane sodium sulfonate (SH 110) and fatty amine polyoxyethylene ether (AEO).

2. The additive according to claim 1, wherein the additive is composed of titanium sulfite, sodium thiazolinyl dithiopropane sulfonate (SH 110) and fatty amine polyoxyethylene ether (AEO) in the amounts of 1-9 mg/L, 10-40 mg/L and 1-11 mg/L, respectively.

3. The additive according to claim 2, wherein the addition amounts of titanium sulfite, sodium thiazolinyl dithiopropane sulfonate (SH 110), and fatty amine polyoxyethylene ether (AEO) are 7 mg/L, 20 mg/L, and 5 mg/L, respectively.

4. The method for using the additive for micro roughening treatment of ultra-low profile copper foil according to claim 1, wherein the method comprises the following specific implementation steps:

(1) Immersing the raw foil into sulfuric acid solution for pickling;

5. The method of claim 4, wherein the basic roughening solution in step (3) is prepared from 80-110 parts g/L H ₂ SO ₄ And 10 to 20 g/L Cu ²⁺ Composition is prepared.

6. The method of claim 4, wherein the electroplating process of step (3) is as follows: the titanium iridium plate is used as an anode, the copper foil is used as a cathode, the temperature is 20-50 ℃, and the current density is 10-50A/dm ² Electrodeposition time is 2-10 s.

7. The method of claim 4, wherein the step (3) comprises adding the additive to the basic roughening solution by: the used additives are respectively dissolved and evenly stirred by deionized water at room temperature, and are simultaneously added into the basic roughening liquid by a metering device at a speed of 2-4L per hour.

8. The method according to claim 4, wherein the copper foil obtained in the step (4) has a surface roughness Rz of 1.3 to 2 μm and a peel strength of 0.4 to 0.6N/mm.