WO2022110536A1

WO2022110536A1 - Low-profile electrolytic copper foil for high-density interconnection circuit board

Info

Publication number: WO2022110536A1
Application number: PCT/CN2021/073866
Authority: WO
Inventors: 王俊锋; 廖平元; 郭志航; 钟孟捷; 刘少华; 王崇华; 庄伟雄; 温丙台; 刘焕添; 叶冬萌; 姚国欢; 王洪杰
Original assignee: 广东嘉元科技股份有限公司
Priority date: 2020-11-27
Filing date: 2021-01-27
Publication date: 2022-06-02
Also published as: GB2607375A; CN112469194A; CN112469194B

Abstract

The present invention relates to the field of copper foil, and in particular to low-profile electrolytic copper foil for a high-density interconnection circuit board. The electrolytic copper foil sequentially comprises a copper foil layer, a roughening treatment layer, a protective barrier layer, a passivation layer and a silane coupling agent layer, wherein the copper foil layer has a thickness of 6-35μm, a weight per unit area of 50-305 g/m² with a weight deviation per unit area less than 5%, a tensile strength more than or equal to 350 N/mm² at 25°C, an elongation more than or equal to 4% at 25°C, a peeling strength more than or equal to 0.7 kg/cm, a roughness of a smooth surface Ra less than or equal to 0.43μm, and a roughness of a rough surface Rz less than or equal to 3.5μm. The electrolytic copper foil provided in the present invention has simple raw materials, is non-toxic and harmless, safe and environment-friendly, has an excellent room-temperature tensile strength and a high-temperature tensile strength, can endure a high temperature of 200°C and has both a good flatness and a low profile, is simple in terms of operation, can completely meet market requirements for electrolytic copper foil for a high-density interconnection circuit board, and has a high added value, a broad environmental applicability and remarkable market competitiveness.

Description

A low-profile electrolytic copper foil for high-density interconnected circuit boards

technical field

The present invention relates to the field of copper foils, and more particularly, to a low-profile electrolytic copper foil for high-density interconnection circuit boards.

Background technique

With the development of electronic products in the direction of light, thin, small, wearable, and multi-functional, new requirements are constantly being put forward for copper foil for multi-layer circuit boards. There are higher requirements for surface roughness, dimensional stability, heat resistance, high-frequency and high-speed characteristics, and thin circuit processing, which continuously promotes the development of copper foil for circuit boards.

Copper Clad Laminate (CCL) is the main component in the circuit board. It is made of insulating film and two upper and lower copper foils after being superimposed by hot pressing process, and then etched to form the required circuit, which is the core board of the circuit board. . However, the traditional ordinary copper foil in the current copper foil substrate cannot meet the requirements of high-density interconnected circuit boards, cannot meet the performance of thin line width and small line spacing, and cannot carry large currents. At the same time, due to the problems of excessive roughness and low elongation at high temperature, the traditional copper foil is prone to short-circuit signals due to the conduction of the upper and lower copper materials on the core board, and thermal expansion and cooling of the film during the process of high temperature and high pressure lamination. The problem of thermal cracking of the copper foil due to shrinkage has a negative impact on the quality and reliability of the subsequently fabricated circuit.

SUMMARY OF THE INVENTION

In view of some problems existing in the prior art, a first aspect of the present invention provides a low-profile electrolytic copper foil, which sequentially includes a copper foil layer, a roughening treatment layer, a protective barrier layer, a passivation layer, and a silane coupling agent layer; the thickness of the copper foil layer is 6-35μm, the weight per unit area is 50-305g/m ² , the weight per unit area deviation is less than 5%, the tensile strength at 25°C is ≥ 350N/mm ² , and the Elongation ≥4%, peel strength ≥0.7kg/cm, smooth surface Ra≤0.43μm, rough surface Rz≤3.5μm.

As a preferred technical solution of the present invention, the copper foil layer is obtained by electrolysis in an electrolyte containing copper ions; the electrolyte includes 250-350g/L copper salt, 70-150g/L inorganic acid , 10-80mg/L chloride salt, 1.5-45mg/L leveling agent.

As a preferred technical solution of the present invention, the leveling agent includes a nonionic cellulose ether and a leveling agent-1, and the leveling agent-1 contains an amino group and a carboxyl group.

As a preferred technical solution of the present invention, the nonionic cellulose ether contains methoxy groups, the methoxy group content is 22-30 wt %, and the substitution degree is 1.3-2.5.

As a preferred technical solution of the present invention, the non-ionic cellulose ether further contains hydroxyethyl group, the content of the hydroxyethyl group is 2.0-14wt%, and the substitution degree is 0.06-0.5.

As a preferred technical solution of the present invention, the weight average molecular weight of the leveling agent-1 is 50000-60000.

As a preferred technical solution of the present invention, the concentration ratio of the nonionic cellulose ether and the leveling agent-1 is 1:(2-5).

As a preferred technical solution of the present invention, the protective barrier layer material is selected from one or more of nickel, titanium, tin, tungsten, molybdenum, and zinc.

As a preferred technical solution of the present invention, the material of the silane coupling agent layer is a silane coupling agent, and the silane coupling agent is selected from 3-glycidyl etheroxypropyltrimethoxysilane, 3-amino Propyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(beta-methoxyethoxy)silane, vinylbenzylaminoethylaminopropyltrimethoxy Silane, 3-(methacryloyloxy)propyltrimethoxysilane, 3-(methacryloyloxy)propyltriethoxysilane, or 3-(methacryloyloxy)propylmethyldisilane One or more of methoxysilanes.

A second aspect of the present invention provides an application of the low-profile electrolytic copper foil in a high-density interconnection circuit board.

Compared with the prior art, the present invention has the following beneficial effects:

The electrolytic copper foil provided by the invention is simple in raw material, non-toxic and harmless, safe and environmentally friendly, has excellent normal temperature tensile strength and high temperature tensile strength, good high temperature oxidation resistance, can withstand high temperature of 200-300 DEG C, and has good The flatness and low profile, simple operation, can fully meet the market requirements for electrolytic copper foil for high-density interconnection circuit boards, with high added value, wide environmental applicability, and significant market competitiveness.

Detailed ways

The present invention is described below through specific embodiments, but is not limited to the specific examples given below.

A first aspect of the present invention provides a low-profile electrolytic copper foil, which sequentially includes a copper foil layer, a roughening treatment layer, a protective barrier layer, a passivation layer, and a silane coupling agent layer.

Copper foil layer

In one embodiment, the thickness of the copper foil layer is 6-35 μm, the weight per unit area is 50-305 g/m ² , the deviation of the weight per unit area is less than 5%, and the tensile strength at 25°C is ≥350 N/mm ^2. The elongation at 25℃ is ≥4%, the peel strength is ≥0.7kg/cm, the smooth surface Ra≤0.43μm, and the rough surface Rz≤3.5μm.

In one embodiment, the copper foil layer is obtained by electrolysis in an electrolyte containing copper ions; the electrolyte includes: 250-350g/L copper salt, 70-150g/L inorganic acid, 10- 80mg/L chloride salt, 1.5-45mg/L leveling agent.

In a preferred embodiment, the electrolyte includes 320 g/L copper salt, 100 g/L inorganic acid, 20 mg/L chloride salt, and 4.5 mg/L leveling agent.

The copper salts described in the present invention are not particularly limited, and those skilled in the art can make routine selections.

In one embodiment, the copper salt is copper sulfate pentahydrate.

In the present invention, copper sulfate pentahydrate is used as the main component of the plating solution to participate in the electrode process. The concentration of copper sulfate pentahydrate is too high, the dispersibility of copper ions is poor, the concentration of anhydrous copper sulfate is too low, and the copper foil layer of the high current layer Burning occurs.

The inorganic acid of the present invention is not particularly limited, and those skilled in the art can make routine selections.

In one embodiment, the inorganic acid is sulfuric acid.

In the present invention, sulfuric acid, as the main component of the plating solution, participates in the electrode process together with copper sulfate pentahydrate, and is interdependent in the process of electroplating.

The chloride salt is not particularly limited in the present invention, and those skilled in the art can make routine selections.

In one embodiment, the chloride salt is hydrochloric acid.

In the present invention, hydrochloric acid, copper sulfate pentahydrate and sulfuric acid are interdependent, and under the condition of improving the conductivity of the plating solution, the uniformity and compactness of the grain texture of the copper foil layer are improved.

The leveling agent is a substance added to the electroplating solution to improve the flatness of the coating, so that the obtained coating is smoother than the surface of the substrate.

During the electroplating process, the microscopic peaks on the surface of the plated parts are more likely to absorb the leveling agent than the valleys, so the deposition resistance there is larger and the deposition rate is slower. After a certain period of time, the microscopic valleys are gradually filled with the coating, so that the coating is leveled. For example, adding butynediol or pyridine and quinoline compounds to the bright nickel plating solution can make the coating bright and have a good leveling effect.

In one embodiment, the leveler includes a nonionic cellulose ether and Leveler-1.

Preferably, the leveling agent-1 contains an amino group and a carboxyl group; further preferably, the weight-average molecular weight of the leveling agent-1 is 50,000-60,000.

The applicant found that adding leveling agent-1 to the electrolyte, the leveling agent-1 containing amino groups and carboxyl groups can improve the leveling effect to a certain extent, but its leveling effect is limited, and the applicant found that the copper foil layer was obtained When the weight average molecular weight of leveling agent-1 is 50000-60000, the leveling effect can be significantly improved, and the tensile strength of the obtained copper foil layer will also be enhanced. , the applicant speculates that the possible reason is that the molecular structure of the leveler-1 with a weight average molecular weight of 50000-60000 has many flexible and irregular serpentine chains, which can be effectively adsorbed on the bumps and cover a large area. At the same time, during the electrolysis process, the leveling agent-1 with a weight average molecular weight of 50000-60000 has a large internal rigidity, and the probability of molecular motion is large. .

In one embodiment, the non-ionic cellulose ether contains methoxy groups, the methoxy group content is 22-30 wt %, and the substitution degree is 1.3-2.5.

Preferably, the non-ionic cellulose ether further contains hydroxyethyl group, the content of the hydroxyethyl group is 2.0-14wt%, and the substitution degree is 0.06-0.5.

More preferably, the non-ionic cellulose ether has a viscosity of 5-200,000 mps in a 2wt% aqueous solution at 20°C.

The applicant unexpectedly found that when the non-ionic cellulose ether contains a methoxy group, and the methoxy group content is 22-30wt%, the degree of substitution is 1.3-2.5; it also contains hydroxyethyl group, and the hydroxyethyl group content is 2.0- 14wt%, the degree of substitution is 0.06-0.5, and at 20°C, the viscosity of the 2wt% aqueous solution is 5-200000mps, the leveling effect of the obtained copper foil layer is better, the applicant believes that the possible reason is that under appropriate conditions The non-ionic cellulose ether has suitable molecular structure and good dispersibility. It can well control the gradual increase of fine copper particles at the position of copper foil bumps, and gradually realize the copper plating process. The top of the particles is smoother and the flatness is increased. . At the same time, the non-ionic cellulose ether under this condition has stronger adsorption to the impurity ions in the electrolyte, and can avoid the generation of pinholes in the electrolytic copper foil.

In one embodiment, the concentration ratio of the leveler-1 to the nonionic cellulose ether is (2-5):1.

Preferably, the concentration ratio of the leveler-1 and the nonionic cellulose ether is 3.5:1.

The applicant unexpectedly found that the high temperature tensile strength of the electrolytic copper foil can also be improved when the concentration ratio of the leveling agent-1 and the nonionic cellulose ether is (2-5): 1. The applicant believes that it is possible The reason is that when the concentration ratio of leveling agent-1 and nonionic cellulose ether is (2:5):1, the leveling agent-1 molecule with weight average molecular weight of 50000-60000 and nonionic cellulose ether A suitable hydrogen bond structure is formed between them, which can further refine the copper particles, so that the weight per unit area of the electrolytic copper foil is maintained at the same level, the error is small, and the mechanical properties at high temperature are improved. 1 has a good protective effect, avoiding the loss of the activity of the leveling agent-1 in the process of electrolysis, which leads to coarse copper particles and affects the uniformity of weight per unit area. The leveling agent-1 molecule can also avoid the defect of reducing the strength of electrolytic copper foil caused by hydroxyethyl cellulose.

In one embodiment, the preparation method of the copper foil layer includes the following steps:

(1) Configure the electrolyte: Mix the copper salt, inorganic acid, chloride salt and leveling agent in the electrolyte evenly at 40-60°C and place it in the electrolytic cell;

(2) Electrochemical reaction: direct current is applied, and under the condition of current density of 40-80A/dm ² , copper foil is precipitated from the cathode, and then peeled off.

In a preferred embodiment, the preparation method of the copper foil layer includes the following steps:

(1) Configure the electrolyte: mix the copper salt, inorganic acid, chloride salt and leveling agent in the electrolyte evenly at 50°C and place it in the electrolytic cell;

(2) Electrochemical reaction: direct current is applied, and under the condition of current density of 70A/dm ² , copper foil is precipitated from the cathode, and then peeled off.

coarsening layer

The roughening treatment is to make the copper foil and the substrate have stronger adhesion. During the roughening process, the current density is higher than the limit current density, and the copper powder is generated and solidified, so that the surface of the copper foil is formed firmly The small granular structure has a highly developed rough surface, forming a high specific surface area. This can strengthen the adhesion and embedding force of resin infiltration and increase the affinity of copper and resin. If in the roughening treatment of copper foil, the crystal layer is relatively flat and the degree of expansion is small, the bonding force between the copper foil and the substrate will be insufficient, and many properties of the plate will be affected.

In one embodiment, the roughening treatment layer is obtained by electrolytic precipitation of the copper foil layer in the roughening treatment liquid.

In one embodiment, the roughening treatment liquid includes 10-50 g/L copper sulfate, 50-150 g/L sulfuric acid, and 1.2-40 g/L additives.

In a preferred embodiment, the roughening treatment liquid includes 38 g/L copper sulfate, 75 g/L sulfuric acid, and 2 g/L additives.

In the present invention, copper sulfate is used as the main salt of the roughening treatment solution, and a star-shaped rough surface is formed on the surface of the copper foil layer. The content of copper sulfate is too high, and the produced copper powder is easy to fall off, which affects the roughening effect, and the content of copper sulfate is too low. , the coarsening effect is not obvious.

In the present invention, sulfuric acid is used as the main component of the roughening treatment liquid, which can promote the precipitation of copper sulfate on the surface of the copper foil layer and improve the stability of the roughening treatment liquid.

In one embodiment, the additive is selected from one or more of sodium tungstate, titanium sulfate, and tin sulfate.

Preferably, the additives are sodium tungstate, titanium sulfate and tin sulfate; further preferably, the concentration ratio of the sodium tungstate, titanium sulfate and tin sulfate is 1:(7-10):(1-5); More preferably, the concentration ratio of the sodium tungstate, titanium sulfate and tin sulfate is 1:8:3.

The additive in the invention is arsenic-free, non-toxic, safe and healthy, and at the same time, sodium tungstate, titanium sulfate and tin sulfate interact to promote the formation of loose tumor bodies on the surface of the copper foil layer, and at the same time, it does not affect the copper ions in copper sulfate and the copper foil. The surface of the layer is precipitated, so that the copper layer covers the surface of the tumor in time, preventing the formation of dendritic copper and inhibiting the generation of copper powder.

In one embodiment, the preparation method of the roughening treatment layer comprises the following steps:

(1) Pickling: pickling the copper foil layer at 10-50°C for 2-20s in a pickling solution including 80-250g/L copper sulfate and 50-150g/L sulfuric acid;

(2) The material obtained in step (1) is electrolyzed for 2-20 seconds at a current density of 5-10A/dm ² at 25° C.

In a preferred embodiment, the preparation method of the roughening treatment layer comprises the following steps:

(1) Pickling: pickling the copper foil layer at 27°C for 10s in a pickling solution including 130g/L copper sulfate and 80g/L sulfuric acid;

(2) The material obtained in step (1) is electrolyzed for 10 seconds at 25° C. and a current density of 10 A/dm ² .

protective barrier

In one embodiment, the protective barrier material is selected from one or more of nickel, titanium, tin, tungsten, molybdenum, and zinc.

Preferably, the protective barrier layer is a nickel and/or zinc layer; further preferably, the protective barrier layer is a nickel and zinc layer.

Zinc coating is the earliest developed barrier layer, which has the advantages of stable process, convenient operation and low cost. The galvanized copper foil has good heat resistance and high bonding strength with the substrate after passivation and organic film coating treatment. However, due to the active chemical properties of zinc, there are disadvantages such as poor corrosion resistance and easy discoloration. Nickel coating has good resistance to high temperature discoloration. In addition, it has better acid resistance than zinc coating, and because of the slow diffusion of nickel, it has high resistance to Cu ²⁺ migration, but it is not easy to be etched in alkaline ammonium persulfate etchant. , it will also leave spots on the printed board and cause contamination. In the present application, the nickel and zinc layers can not only combine the advantages of the nickel layer and the zinc layer, but also effectively perform plating on the roughening treatment layer to improve the bonding strength of the roughening treatment layer and the protective barrier layer.

In one embodiment, the protective barrier layer is obtained by electrolysis in a protective barrier liquid on the surface of the roughened treatment layer.

In one embodiment, the protective barrier liquid includes 20-100 g/L sulfuric acid, 0.25-2 g/L Ni ²⁺ , 0.50-5 g/L Zn ²⁺ , and 50-300 mg/L protective barrier liquid additives.

In a preferred embodiment, the protective blocking liquid includes 20-100 g/L sulfuric acid, 1 g/L Ni ²⁺ , 3 g/L Zn ²⁺ , and 150 mg/L protective blocking liquid additives.

The concentration of sulfuric acid in the protective barrier solution of the present invention is adjusted to make it pH=3.0-6.0, preferably pH 5.

The pH=3.0-6.0 in the protective barrier liquid of the present application ensures the dispersibility of ions in the protective barrier liquid on the one hand, and ensures stable deposition of nickel ions and zinc ions with good uniformity on the other hand.

In one embodiment, the protective barrier fluid additive is saccharin and/or benzyltriethylammonium bromide.

Preferably, the protective barrier fluid additive is benzyltriethylammonium bromide.

In the present invention, benzyltriethylammonium bromide can make the nickel and zinc layers in the present invention evenly electroplated on the surface of the roughened treatment layer, thereby improving the surface smoothness of the electrolytic copper foil.

In one embodiment, the preparation method of the protective barrier layer includes: electrolyzing the roughened treatment layer at 30-60° C. and 0.5-2.0 A/dm ² for 2-10 s.

In a preferred embodiment, the preparation method of the protective barrier layer includes: electrolyzing the roughened treated layer for 8s under the conditions of 50° C. and 1.5A/dm ² .

passivation layer

In one embodiment, the passivation layer is obtained by electrolysis in a passivation treatment solution on the surface of the protective barrier layer.

In one embodiment, the passivation treatment solution includes 2.0-20 g/L Na ₂ SO ₄ , 0.2-3.0 g/L Zn ²⁺ , and 0.5-5.0 g/L CrO ₃ .

Preferably, the passivation treatment solution includes 15 g/L Na ₂ SO ₄ , 1.8 g/L Zn ²⁺ , and 3.2 g/L CrO ₃ .

The passivation treatment solution of suitable concentration makes the passivation treatment layer dense and fine in this application, and forms a dense and complex film layer on the surface of the protective barrier layer, so that it will not be oxidized and discolored by direct contact with the air, and the film layer and the protective barrier layer are at the same time. The bond strength between the layers is high and the protection time is long lasting.

In one embodiment, the preparation method of the passivation layer includes: electrolyzing the protective barrier layer under the conditions of 30-60° C. and 0.5-5 A/dm ² for 1-10 s.

In a preferred embodiment, the preparation method of the passivation layer includes: electrolyzing the protective barrier layer at 40° C. and 3.2 A/dm ² for 2-8 s.

Silane coupling agent layer

In one embodiment, the material of the silane coupling agent layer is a silane coupling agent, and the silane coupling agent is selected from 3-glycidyloxypropyltrimethoxysilane, 3-aminopropyltriethylsilane Oxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(beta-methoxyethoxy)silane, vinylbenzylaminoethylaminopropyltrimethoxysilane, 3 -(methacryloyloxy)propyltrimethoxysilane, 3-(methacryloyloxy)propyltriethoxysilane, or 3-(methacryloyloxy)propylmethyldimethoxysilane one or more of them.

Preferably, the silane coupling agent is 3-glycidyloxypropyltrimethoxysilane.

3-Glycidoxypropyltrimethoxysilane is an epoxy-containing coupling agent, which can easily form a uniform organic film layer on the surface of the passivation layer of the present invention, further improving the anti-oxidation ability, and at the same time The wettability between 3-glycidyloxypropyltrimethoxysilane and the surface of the passivation layer is better, and better bonding strength is obtained. In addition, the bonding strength between the obtained silane coupling layer and the substrate is better .

In one embodiment, the preparation method of the silane coupling agent layer includes: spraying the surface of the passivation layer with 0.1-3 wt % of the silane coupling agent.

Preferably, the preparation method of the silane coupling agent layer includes: spraying the surface of the passivation layer with 2 wt % of the silane coupling agent.

The solvents of the electrolyte solution, the roughening treatment solution, the protective barrier solution and the passivation treatment solution in the present invention are all water.

In one embodiment, the water is deionized water.

A second aspect of the present invention provides an application of the electrolytic copper foil in a high-density interconnected circuit board.

Example

Hereinafter, the present invention will be described in more detail by means of examples, but it should be understood that these examples are merely illustrative and not restrictive. Unless otherwise stated, the raw materials used in the following examples are all commercially available.

Example 1

Embodiment 1 of the present invention provides a low-profile electrolytic copper foil for a high-density interconnected circuit board, which sequentially includes a copper foil layer, a roughening treatment layer, a protective barrier layer, a passivation layer, and a silane coupling agent layer.

The copper foil layer is obtained by electrolysis in an electrolyte solution containing copper ions; the electrolyte solution is 250g/L copper salt, 70g/L inorganic acid, 10mg/L chloride salt, and 1.5mg/L leveling agent.

The copper salt is copper sulfate pentahydrate; the inorganic acid is sulfuric acid; the chloride salt is hydrochloric acid; the leveling agent is nonionic cellulose ether and leveling agent-1; the leveling agent-1 Contains amino and carboxyl groups, weight average molecular weight is 50000-60000, CAS: 9000-70-8, purchased from Rock Chemical; the non-ionic cellulose ether contains methoxy and hydroxyethyl, and the methoxy content is 22- 30wt%, the substitution degree is 1.3-2.5; the hydroxyethyl content is 2.0-14wt%, the substitution degree is 0.06-0.5, and the viscosity of the 2wt% aqueous solution is 5-200000mps at 20°C. The concentration ratio of the leveling agent-1 and the nonionic cellulose ether is 2:1.

The preparation method of the copper foil layer is as follows: (1) Configuring an electrolyte: Mix the copper salt, inorganic acid, chloride salt and leveling agent in the electrolyte at 40°C evenly, and place it in an electrolytic cell;

(2) Electrochemical reaction: direct current is applied, under the condition of current density 40A/dm ² , copper foil is precipitated from the cathode, and then peeled off.

The roughening treatment layer is obtained by electrolytic precipitation of the copper foil layer in the roughening treatment liquid.

The roughening treatment liquid was 10 g/L copper sulfate, 50 g/L sulfuric acid, and 1.2 g/L additive.

The additives are sodium tungstate, titanium sulfate and tin sulfate, and their concentration ratio is 1:7:1.

The preparation method of the roughening treatment layer is as follows:

(1) Pickling: pickling the copper foil layer at 10°C for 20s in a pickling solution including 80g/L copper sulfate and 50g/L sulfuric acid;

(2) The material obtained in step (1) is electrolyzed at 25° C. and a current density of 5 A/dm ² for 20 seconds to obtain the result.

The protective barrier layers are nickel and zinc layers.

The protective barrier layer is obtained by electrolysis in the protective barrier liquid on the surface of the roughened treatment layer.

The protective blocking liquid is 20 g/L sulfuric acid, 0.25 g/L Ni ²⁺ , 0.50 g/L Zn ²⁺ , and 50 mg/L protective blocking liquid additives.

The protective barrier liquid additive is benzyltriethylammonium bromide.

The specific preparation method of the protective barrier layer is as follows: electrolyzing the roughened treated layer for 10s under the conditions of 30° C. and 2.0A/dm ² .

The passivation layer is obtained by electrolysis in a passivation treatment solution on the surface of the protective barrier layer.

The passivation treatment solution was 2.0 g/L Na ₂ SO ₄ , 0.2 g/L Zn ²⁺ , and 0.5 g/L CrO ₃ .

The specific preparation method of the passivation layer is as follows: electrolyzing the protective barrier layer for 10s under the conditions of 30° C. and 0.5A/dm ² .

The preparation method of the silane coupling agent layer includes: spraying the surface of the passivation layer with 0.1 wt % of the silane coupling agent.

The silane coupling agent is 3-glycidyloxypropyltrimethoxysilane.

Example 2

Embodiment 2 of the present invention provides a low-profile electrolytic copper foil for a high-density interconnected circuit board, which sequentially includes a copper foil layer, a roughening treatment layer, a protective barrier layer, a passivation layer, and a silane coupling agent layer.

The copper foil layer is obtained by electrolysis in an electrolyte solution containing copper ions; the electrolyte solution is 350g/L copper salt, 150g/L inorganic acid, 80mg/L chloride salt, and 45mg/L leveling agent.

The copper salt is copper sulfate pentahydrate; the inorganic acid is sulfuric acid; the chloride salt is hydrochloric acid; the leveling agent is nonionic cellulose ether and leveling agent-1; the leveling agent-1 Contains amino and carboxyl groups, weight average molecular weight is 50000-60000, CAS: 9000-70-8, purchased from Rock Chemical; the non-ionic cellulose ether contains methoxy and hydroxyethyl, and the methoxy content is 22- 30wt%, the substitution degree is 1.3-2.5; the hydroxyethyl content is 2.0-14wt%, the substitution degree is 0.06-0.5, and the viscosity of the 2wt% aqueous solution is 5-200000mps at 20°C. The concentration ratio of the leveling agent-1 and the nonionic cellulose ether is 5:1.

The preparation method of the copper foil layer is as follows: (1) Configuring the electrolyte: Mix the copper salt, inorganic acid, chloride salt and leveling agent in the electrolyte evenly at 60°C, and place it in an electrolytic cell;

(2) Electrochemical reaction: direct current is applied, under the condition of current density of 80A/dm ² , copper foil is precipitated at the cathode, and then peeled off.

The roughening treatment liquid is 50 g/L copper sulfate, 150 g/L sulfuric acid, and 40 g/L additive.

The additives are sodium tungstate, titanium sulfate and tin sulfate, and their concentration ratio is 1:10:5.

The preparation method of the roughening treatment layer is as follows:

(1) Pickling: pickling the copper foil layer in a pickling solution at 50°C for 2s, the pickling solution includes 250g/L copper sulfate and 150g/L sulfuric acid;

(2) The material obtained in step (1) is electrolyzed for 2 seconds at 25° C. and a current density of 10 A/dm ² .

The protective barrier layers are nickel and zinc layers.

The protective blocking liquid is 100 g/L sulfuric acid, 2.0 g/L Ni ²⁺ , 5.00 g/L Zn ²⁺ , and 300 mg/L protective blocking liquid additives.

The protective barrier liquid additive is benzyltriethylammonium bromide.

The specific preparation method of the protective barrier layer is as follows: electrolyzing the roughened treated layer for 2 s under the conditions of 60° C. and 2.0 A/dm ² .

The passivation treatment solution was 20 g/L Na ₂ SO ₄ , 3 g/L Zn ²⁺ , and 5 g/L CrO ₃ .

The specific preparation method of the passivation layer is as follows: electrolyzing the protective barrier layer for 3 s under the conditions of 60° C. and 5 A/dm ² .

The preparation method of the silane coupling agent layer includes: spraying the surface of the passivation layer with 3 wt % of the silane coupling agent.

The silane coupling agent is 3-glycidyloxypropyltrimethoxysilane.

Example 3

Embodiment 3 of the present invention provides a low-profile electrolytic copper foil for a high-density interconnected circuit board, which sequentially includes a copper foil layer, a roughening treatment layer, a protective barrier layer, a passivation layer, and a silane coupling agent layer.

The copper foil layer is obtained by electrolysis in an electrolyte solution containing copper ions; the electrolyte solution is 320g/L copper salt, 100g/L inorganic acid, 20mg/L chloride salt, and 4.5mg/L leveling agent.

The copper salt is copper sulfate pentahydrate; the inorganic acid is sulfuric acid; the chloride salt is hydrochloric acid; the leveling agent is nonionic cellulose ether and leveling agent-1; the leveling agent-1 Contains amino and carboxyl groups, weight average molecular weight is 50000-60000, CAS: 9000-70-8, purchased from Rock Chemical; the non-ionic cellulose ether contains methoxy and hydroxyethyl, and the methoxy content is 22- 30wt%, the substitution degree is 1.3-2.5; the hydroxyethyl content is 2.0-14wt%, the substitution degree is 0.06-0.5, and the viscosity of the 2wt% aqueous solution is 5-200000mps at 20°C. The concentration ratio of the leveling agent-1 and the nonionic cellulose ether is 3.5:1.

The preparation method of the copper foil layer is as follows: (1) Configuring an electrolyte: Mix the copper salt, inorganic acid, chloride salt and leveling agent in the electrolyte evenly at 50°C, and place it in an electrolytic cell;

The roughening treatment liquid was 38 g/L copper sulfate, 75 g/L sulfuric acid, and 2 g/L additives.

The additives are sodium tungstate, titanium sulfate and tin sulfate, and their concentration ratio is 1:8:3.

The preparation method of the roughening treatment layer is as follows:

The protective barrier layers are nickel and zinc layers.

The protective blocking liquid is 60 g/L sulfuric acid, 1 g/L Ni ²⁺ , 3 g/L Zn ²⁺ , and 150 mg/L protective blocking liquid additives.

The protective barrier liquid additive is benzyltriethylammonium bromide.

The specific preparation method of the protective barrier layer is as follows: electrolyzing the roughened treatment layer for 8s under the conditions of 50° C. and 1.5A/dm ² .

The passivation treatment solution was 15 g/L Na ₂ SO ₄ , 1.8 g/L Zn ²⁺ , and 3.2 g/L CrO ₃ .

The specific preparation method of the passivation layer is as follows: electrolyzing the protective barrier layer for 8s under the conditions of 40° C. and 3.2A/dm ² .

The preparation method of the silane coupling agent layer includes: spraying 2wt% of the silane coupling agent on the surface of the passivation layer.

The silane coupling agent is 3-glycidyloxypropyltrimethoxysilane.

Example 4

Embodiment 4 of the present invention provides a low-profile electrolytic copper foil for high-density interconnection circuit boards, the specific implementation of which is the same as that of Embodiment 3, except that the leveling agent is nonionic The nonionic cellulose ether contains methoxy and hydroxyethyl, the methoxy content is 22-30wt%, the degree of substitution is 1.3-2.5; the hydroxyethyl content is 2.0-14wt%, the degree of substitution is 0.06-0.5, and the 20°C, 2wt% aqueous solution viscosity is 5-200000mps.

The specific embodiments of the method for preparing the copper foil layer, the method for preparing the roughening treatment layer, the method for preparing the protective barrier layer, the method for preparing the passivation layer and the method for preparing the silane coupling agent are the same as those in Example 3.

Example 5

Embodiment 5 of the present invention provides a low-profile electrolytic copper foil for high-density interconnection circuit boards. Agent-1, the non-ionic soluble cellulose ether contains methoxyl group and hydroxyethyl group, purchased from Anhui Zhonghong Bioengineering Co., Ltd., the item number is 123456; the leveling agent-1 contains amino group and carboxyl group, heavy The average molecular weight is 50000-60000, CAS: 9000-70-8; the concentration ratio of the leveling agent-1 and the nonionic cellulose ether is 3.5:1.

Example 6

Embodiment 6 of the present invention provides a low-profile electrolytic copper foil for high-density interconnection circuit boards. Agent-1, the non-ionic cellulose ether is hydroxyethyl cellulose, the degree of substitution (D*S) is 1.8-2.0, and the viscosity of a 2wt% aqueous solution is 30000-40000mps, purchased from Czechst Biotechnology; the Leveling agent-1 contains amino and carboxyl groups, weight average molecular weight is 50000-60000, CAS: 9000-70-8, purchased from Rock Chemical; the concentration ratio of leveling agent-1 and non-ionic cellulose ether is 3.5 :1.

Example 7

Embodiment 7 of the present invention provides a low-profile electrolytic copper foil for high-density interconnection circuit boards, the specific implementation of which is the same as that of Embodiment 3, except that the leveling agent is leveling Leveling agent-1 contains amino and carboxyl groups, weight average molecular weight is 50000-60000, CAS: 9000-70-8.

Example 8

Embodiment 8 of the present invention provides a low-profile electrolytic copper foil for high-density interconnection circuit boards. The concentration ratio is 7:1.

Example 9

Embodiment 9 of the present invention provides a low-profile electrolytic copper foil for high-density interconnection circuit boards. The concentration ratio is 0.8:1.

performance evaluation

1. Weight per unit area: The weight per unit area of the copper foil layer obtained in Examples 1-9 is tested according to the GB/T5230-1995 standard, and each embodiment is tested 10 times to calculate the weight per unit area deviation, and the weight per unit area deviation＜ 3.0%, recorded as excellent; deviation of weight per unit area of 3-5.0%, recorded as good; deviation of weight per unit area > 5%, recorded as poor.

2. Roughness: The roughness of the copper foil layers obtained in Examples 1-9 was tested according to the GB/T 5230-1995 standard. Test profile arithmetic mean deviation (Ra) and ten-point average height of microscopic roughness (Rz), Ra is the arithmetic mean of the absolute value of profile deviation within the sampling length; Rz is the five largest profile peak heights within the sampling length The difference between the average of and the average of the 5 largest contour valley depths. Ra<0.15μm, recorded as the first grade; Ra is 0.15-0.3μm, recorded as the second grade; Ra>0.3μm, recorded as the third grade. Rz<1.5μm, recorded as the first grade; Rz of 1.5-2.5μm, recorded as the second grade; Rz of 2.5-3.5μm, recorded as the third grade.

3. Tensile strength at room temperature: The tensile strength of the copper foil layers obtained in Examples 1-9 was tested according to the GB/T5230-1995 standard, and the test temperature was 25°C. Tensile strength ≥ 350N/ ^mm2 is recorded as qualified, and tensile strength <350N/ ^mm2 is recorded as unqualified.

4. High-temperature tensile strength: The high-temperature tensile strength of the copper foil layers obtained in Examples 1-9 was tested, and the test temperature was 200° C. The operation method was based on the GB/T 5230-1995 standard. Calculate the tensile strength change rate, tensile strength change rate (%) = (room temperature tensile strength - high temperature tensile strength) / room temperature tensile strength * 100%, tensile strength change rate <30%, denoted as A grade, Tensile strength change rate of 30-50%, recorded as B grade, tensile strength change rate > 50% recorded as C grade.

Table 1

The foregoing examples are illustrative only and serve to explain some of the features of the methods described herein. The appended claims are intended to claim the broadest conceivable scope and the embodiments presented herein are merely illustrative of selected implementations according to a combination of all possible embodiments. Accordingly, it is the applicant's intention that the appended claims not be limited by the selection of examples that characterize the invention. Some numerical ranges used in the claims also include sub-ranges within them, and variations within these ranges should also be construed, where possible, to be covered by the appended claims.

Claims

A low-profile electrolytic copper foil is characterized in that it sequentially includes a copper foil layer, a roughening treatment layer, a protective barrier layer, a passivation layer, and a silane coupling agent layer; the thickness of the copper foil layer is 6-35 μm, Weight per unit area is 50-305g/m 2 , deviation of weight per unit area is less than 5%, tensile strength at 25℃≥350N/mm 2 , elongation at 25℃≥4%, peel strength≥0.7kg/cm , smooth surface Ra≤0.43μm, rough surface Rz≤3.5μm.
The low-profile electrolytic copper foil according to claim 1, wherein the copper foil layer is obtained by electrolysis in an electrolyte containing copper ions; the electrolyte comprises 250-350g/L copper salt, 70- 150g/L inorganic acid, 10-80mg/L chloride salt, 1.5-45mg/L leveling agent.
The low-profile electrolytic copper foil according to claim 2, wherein the leveling agent comprises a nonionic cellulose ether and a leveling agent-1, and the leveling agent-1 contains an amino group and a carboxyl group.
The low-profile electrolytic copper foil according to claim 3, wherein the non-ionic cellulose ether contains methoxy groups, the methoxy group content is 22-30 wt%, and the substitution degree is 1.3-2.5.
The low-profile electrolytic copper foil according to claim 4, wherein the non-ionic cellulose ether further contains a hydroxyethyl group, the content of the hydroxyethyl group is 2.0-14 wt%, and the substitution degree is 0.06-0.5.
The low-profile electrolytic copper foil according to claim 3, wherein the leveling agent-1 has a weight average molecular weight of 50,000-60,000.
The low-profile electrolytic copper foil according to any one of claims 3-6, characterized in that, the concentration ratio of the non-ionic cellulose ether and the leveling agent-1 is 1:(2-5).
The low-profile electrolytic copper foil according to any one of claims 3-6, wherein the protective barrier layer material is selected from one or more of nickel, titanium, tin, tungsten, molybdenum, and zinc.
The low-profile electrolytic copper foil according to any one of claims 3-6, wherein the material of the silane coupling agent layer is a silane coupling agent, and the silane coupling agent is selected from 3-glycidyl etheroxy propyltrimethoxysilane, 3-aminopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(beta-methoxyethoxy)silane, vinyl Benzylaminoethylaminopropyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, 3-(methacryloyloxy)propyltriethoxysilane, or 3-(methacryloyloxy)propyltriethoxysilane One or more of acryloyloxy)propylmethyldimethoxysilane.
An application of the low-profile electrolytic copper foil according to any one of claims 1-9 in a high-density interconnected circuit board.