Patent Application
20250092555
This application claims the priority benefit of Taiwan application serial no. 112135618, filed on Sep. 19, 2023. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
The disclosure relates to a manufacturing method of a roughened copper foil.
With advances in fine lines on printed circuit boards (PCBs), a roughening layer on a surface of a copper foil is desirably fine while high adhesion between the copper foil and an insulating resin is to be retained. Hence, it is indeed a challenge to fabricate a roughening layer of low roughness and high adhesion on the copper foil.
The disclosure provides a manufacturing method of a roughened copper foil, in which a
roughening layer of low roughness and high adhesion can be fabricated on a copper foil.
The manufacturing method of a roughened copper foil of the disclosure includes the following steps. A copper foil is provided. An electrolytic process is performed to form a roughening layer on the copper foil. An electrolyte solution in the electrolytic process includes copper ions in a range from 0.1 g/L to 20 g/L, sulfate ions in a range from 30 g/L to 120 g/L, and a coordination compound in a range from 0.1 g/L to 10 g/L.
In an embodiment of the disclosure, the coordination compound includes a benzotriazole-based compound, a propanesulfonic acid-based compound, ethylenediaminetetraacetic acid or a combination thereof.
In an embodiment of the disclosure, no other metal ions are further added to the electrolyte solution.
In an embodiment of the disclosure, the electrolytic process includes a first electrolytic process and a second electrolytic process, and a first concentration of the copper ions used in the first electrolytic process is lower than a second concentration of the copper ions used in the second electrolytic process.
In an embodiment of the disclosure, the first concentration of the copper ions is from 0.1 g/L to 10 g/L, and the second concentration of the copper ions is from 1 g/L to 20 g/L.
In an embodiment of the disclosure, a silylation treatment process is further performed after the electrolytic process is performed.
In an embodiment of the disclosure, the electrolytic process uses direct current.
In an embodiment of the disclosure, a temperature of the electrolytic process is from 25° C. to 60° C.
In an embodiment of the disclosure, current density of the electrolytic process is from 1 A/dm2 to 120 A/dm2.
In an embodiment of the disclosure, duration of the electrolytic process is from 1 second to 45 seconds.
In light of the foregoing, in the disclosure, the electrolyte solution used in forming the roughening layer is improved by including the copper ions in the range from 0.1 g/L to 20 g/L, the sulfate ions in the range from 30 g/L to 120 g/L, and the coordination compound in the range from 0.1 g/L to 10 g/L. Thus, copper nodules that constitute the roughening layer can be formed through a superior nucleation and growth mechanism. The roughening layer of low roughness and high adhesion can therefore be fabricated on the copper foil.
To make the aforementioned more comprehensible, several embodiments accompanied with drawings are described in detail as follows.
In the following detailed description, for the sake of explanation and not limitation, exemplary embodiments revealing specific details are set forth to provide a thorough understanding of various principles of the disclosure. However, it is obvious to those skilled in the art that, benefiting from the disclosure, the disclosure may be practiced in other embodiments that depart from the specific details disclosed herein. In addition, the description of well-known devices, methods, and materials may be omitted so as not to obscure the description of various principles of the disclosure.
In the present specification, a range represented by “a numerical value to another numerical value” is a schematic representation for avoiding listing all of the numerical values in the range in the specification. Therefore, the recitation of a specific numerical range covers any numerical value in the numerical range and a smaller numerical range defined by any numerical value in the numerical range, as is the case with any numerical value and the smaller numerical range in the specification.
Unless otherwise specified, the term “from . . . to . . . ” used in the specification to define a numerical range is intended to cover a range equal to and between the stated endpoint values. For example, “a size range from a first numerical value to a second numerical value” means that the size range may cover the first numerical value, the second numerical value, and any numerical value between the first numerical value and the second numerical value.
In the specification, non-limiting terms (such as “possible,” “may be,” “for example,” or other similar terms) are unessential or optional implementations, inclusions, additions or existences.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It is further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In the embodiment, a roughened copper foil may be manufactured through, for example, the following steps. Firstly, a copper foil is provided. Next, an electrolytic process is performed so as to form a roughening layer on the copper foil. In the disclosure, an electrolyte solution used in forming the roughening layer is improved by including copper ions in a range from 0.1 g/L to 20 g/L (for example, 0.1 g/L, 1 g/L, 10 g/L, 20 g/L, or any numeric value between 0.1 g/L and 20 g/L), sulfate ions (SO42-) in a range from 30 g/L to 120 g/L (for example, 30 g/L, 50 g/L, 70 g/L, 90 g/L, 120 g/L, or any numeric value between 30 g/L and 120 g/L), and a coordination compound in a range from 0.1 g/L to 10 g/L (for example, 0.1 g/L, 1 g/L, 3 g/L, 5 g/L, 7 g/L, 10 g/L, or any numeric value between 0.1 g/L and 10 g/L). Thus, copper nodules that constitute the roughening layer can be formed through a superior nucleation and growth mechanism, such as at a high nucleation rate. A roughening layer of low roughness and high adhesion (large surface area and high peel resistance) can therefore be fabricated on the copper foil. The thus formed roughening layer has surface roughness (for example, ten point average roughness (Rz)) of, for example, at least less than 1 micrometer, and peel resistance between the copper foil on which the roughening layer is formed and an insulating resin (prepreg) is, for example, at least greater than 4 lb/in.
Furthermore, the coordination compound is added to the electrolyte solution of the disclosure. Thus, in comparison with current electrodeposited copper foil that only uses cupric sulfate electrolyte solution, a superior nucleation and growth mechanism can be achieved by causing divalent copper ions (Cu2+) in the electrolyte solution to form copper ions of other valences (such as monovalent copper ions (Cu+)) through a complex reaction between the coordination compound and copper, and growth capacity of the copper nodules in three dimensions can be optimized. For example, the coordination compound of the disclosure includes a benzotriazole (BTA)-based compound (ionic liquid), a propanesulfonic acid-based compound, ethylenediaminetetraacetic acid (EDTA) or a combination thereof. The benzotriazole (BTA)-based compound is selected from, for example, carboxybenzotriazole (CBTA), 1,2,3-benzotriazole, 1-chloro-1,2,3-benzotriazole, bis(N-2-ethylhexyl)aminomethylene-1,2,3-benzotriazole, bis(N-2-ethylhexyl)aminomethylene-1,2,3-toluenetriazole, and bis(N-2-hydroxyethyl)aminomethylene-1,2,3-benzotriazole. The propanesulfonic acid-based compound is selected from, for example, bis-(3-sulfopropyl)-disulfide disodium salt (SPS) and 3-mercapto-1-propanesulfonic acid (MPS). However, the disclosure is not limited thereto.
In some embodiments, the manufacturing method of a roughened copper foil of the disclosure may be applied in a circuit board, yet the disclosure is not limited thereto.
In some embodiments, no other metal ions are further added to the electrolyte solution. For example, the electrolyte solution of the disclosure does not include metal ions such as iron (Fe) or cobalt (Co) ions. In other words, the electrolyte solution includes ions of a single metal (copper ions), yet the disclosure is not limited thereto.
In some embodiments, the electrolytic process may be performed in a plurality of phases so as to effectively obtain the desired copper nodules. For example, the electrolytic process includes a first electrolytic process and a second electrolytic process, and a first concentration of the copper ions used in the first electrolytic process is lower than a second concentration of the copper ions used in the second electrolytic process. Thus, it is possible to first grow the copper nodules to a desired extent (such as into dendrites) in a vertical direction by the first electrolytic process, and then thicken a base portion (portion near the copper foil) of the copper nodules by the second electrolytic process, so as to increase adhesion between the copper nodules and the copper foil and prevent peeling-off. The first concentration of the copper ions is from 0.1/L to 10 g/L, and the second concentration of the copper ions is from 1 g/L to 20 g/L. However, the disclosure is not limited thereto.
The size and shape of the copper nodules mentioned herein may depend on the actual design requirements. The disclosure does not limit the size and shape of the copper nodules as long as the surface roughness (Rz) of the roughening layer is at least less than 1 micrometer and the peel resistance between the copper foil on which the roughening layer is formed and the insulating resin (prepreg) is at least greater than 4 lb/in.
In some embodiments, the copper foil has a thickness of from 1.5 micrometers to 70 micrometers, yet the disclosure is not limited thereto.
In some embodiments, after the electrolytic process is performed, a silylation treatment process is further performed to additionally form a silane coupling layer on a surface of the roughening layer opposite to the copper foil. Hence, a bonding force between the roughening layer and other layers in the subsequent processes is enhanced. The silylation treatment process may be performed by using a silane coupling agent such as acryloxypropyl trimethoxysilane and the like, yet the disclosure is not limited thereto.
In some embodiments, operation conditions of the electrolytic process include use of direct current, a temperature of the electrolytic process of from 25° C. to 60° C. (for example, 25° C., 35° C., 45° C., 55° C., 60° C., or any temperature between 25° C. and 60° C.), current density of the electrolytic process of from 1 A/dm2 (ASD) to 120 A/dm2 (for example, 1 A/dm2, 10 A/dm2, 30 A/dm2, 50 A/dm2, 80 A/dm2, 120 A/dm2, or any current density between 1 A/dm2 and 120 A/dm2), and duration of the electrolytic process of from 1 second to 45 seconds (for example, 1 second, 10 seconds, 20 seconds, 30 seconds, 45 seconds, or any duration between 1 second and 45 seconds), yet the disclosure is not limited thereto.
In some embodiments, in the case where a benzotriazole-containing compound instead of benzotriazole is added to a copper tank of the disclosure, the surface roughness (Rz) is from 1 micrometer to 1.5 micrometers and the peel resistance is greater than 4 lb/in. In contrast, in the case where neither benzotriazole nor a benzotriazole-containing compound is added to the copper tank, the surface roughness (Rz) is from 1 micrometer to 1.5 micrometers, and the peel resistance is less than 3 lb/in. However, the disclosure is not limited thereto.
An example and a comparative example are given below to describe the effects of the disclosure. However, the scope of the disclosure is not limited to the scope of these examples.
Roughened copper foils manufactured respectively using electrolyte solution formulations of the example and the comparative example shown in Table 1 were used to manufacture copper foil substrates with a model number NPG170D, and the copper foil substrates were evaluated according to the following methods.
Surface roughness (Rz): measured using laser or white light.
Peel resistance: the peel resistance of the metal substrates was measured according to the method described in IPC-TM-650-2.4.8.
Relevant characteristics of the manufactured copper foil substrates were measured and results thereof are as shown in Table 1. By a comparison between the example and the comparative example in Table 1, a conclusion can be reached that the peel resistance can be improved by adding a benzotriazole coordination compound.
In a nutshell, in the disclosure, the electrolyte solution used in forming the roughening layer is improved by including the copper ions in the range from 0.1 g/L to 20 g/L, the sulfate ions in the range from 30 g/L to 120 g/L, and the coordination compound in the range from 0.1 g/L to 10 g/L. Thus, the copper nodules that constitute the roughening layer can be formed through a superior nucleation and growth mechanism. The roughening layer of low roughness and high adhesion can therefore be fabricated on the copper foil.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 112135618 | Sep 2023 | TW | national |
