TWM543249U - Electrolysis copper foil with surface layer containing fur-shape structure and circuit board component - Google Patents

Description

Electrolytic copper foil with a fluffy structure on the surface layer and a circuit board assembly

The present invention relates to an electrolytic copper foil and a circuit board assembly, and more particularly to an electrolytic copper foil having a pile-like structure on the surface layer, and a circuit board assembly using an electrolytic copper foil having a pile-like structure on the surface layer.

The copper foil currently applied to the printed circuit board is formed by electroplating on the cathode wheel to form a raw foil, and then processed through a post-stage process to form a final product. The post-processing includes performing a roughening treatment on the rough surface of the original foil to form a plurality of copper tumors on the rough surface of the original foil, thereby increasing the bonding strength between the copper foil and the circuit substrate, that is, increasing the peel strength of the copper foil.

However, in recent years, electronic products have been moving toward high-frequency and high-speed, and when a high-frequency signal is transmitted, a so-called skin effect is generated. In the patent document 1 (Japanese Patent No. 5116943), a copper foil for a high-frequency circuit and a method for producing the same are provided, and a copper foil having a large roughness on the surface of the copper foil and having a large roughness is described. As the signal travels longer, the problem of signal attenuation and delay is created. In other words, the smoother the surface of the copper foil, the less the loss of the signal transmitted in the conductor. Therefore, the flatness of the surface of the copper foil plays a very important role. If the surface roughness of the copper foil is higher, it is more likely to be lost when transmitting high frequency signals.

However, if the roughness of the surface of the copper foil is lowered to reduce the transmission loss of the high-frequency signal, the peel strength of the copper foil and the circuit substrate is reduced. Therefore, how to maintain the flatness of the surface of the copper foil while improving the peeling strength of the copper foil is a major issue developed by the industry.

The technical problem to be solved by the present invention is to provide an electrolytic copper foil having a pile-like structure and a wiring board assembly in view of the deficiencies of the prior art.

One of the technical solutions adopted in the present invention is to provide an electrolytic copper foil having a fluff-like structure, which comprises a green foil layer and a surface treatment layer on the green foil layer, and the surface treatment layer comprises a plurality of fluffy copper tumors. Wherein each of the fluffy copper tumors has a largest major axis diameter and a largest minor axis diameter, the largest major axis diameter is between 0.5 μm and 1.5 μm, and the largest minor axis diameter is between 0.1 μm and 1.0 Between μm, and a villus-like accommodation space is formed between each two adjacent fluffy copper tumors.

Another technical solution adopted by the present invention is to provide a circuit board assembly including a substrate, at least one circuit layer on the substrate, and an adhesive layer connected between the substrate and the circuit layer, wherein the circuit The layer is an electrolytic copper foil having a pile-like structure on the surface layer, and the adhesive layer is filled in the pile-like accommodation space.

Another technical solution adopted by the present invention is to provide a circuit board assembly comprising a substrate and at least one circuit layer on the substrate, wherein the circuit layer is an electrolytic copper foil having a fluff-like structure on the surface layer. And a part of the substrate is filled in the fluff-like accommodation space.

The beneficial effect of the present invention is that by making the surface layer of the electrolytic copper foil have a fluffy copper tumor, the peeling strength between the electrolytic copper foil and the substrate can be improved without increasing the surface roughness of the electrolytic copper foil, thereby The fabricated electrolytic copper foil with a fluffy structure on the surface can be used to transmit high frequency signals.

In order to further understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the accompanying drawings. However, the drawings are provided for reference and description only, and are not intended to limit the present invention.

1‧‧‧electrolytic copper foil

10, 210‧‧‧ raw foil layer

10a‧‧‧Smooth face

10b‧‧‧Rough surface

11, 211‧‧‧ surface treatment layer

110, 211a‧‧ ‧ fluffy copper tumor

D1‧‧‧Maximum long shaft diameter

D2‧‧‧Maximum short shaft diameter

S1‧‧‧Flour-like accommodation space

P1‧‧‧ spacing

T‧‧‧ total thickness

t‧‧‧Surface treatment layer thickness

2, 2'‧‧‧ circuit board assembly

20‧‧‧Substrate

21‧‧‧Line layer

22‧‧‧Adhesive layer

Fig. 1 is a partial cross-sectional view showing the electrolytic copper foil of the present embodiment.

2 is a partial enlarged view of the electrodeposited copper foil of FIG. 1 in a region II.

Fig. 3 is a photograph of an electrolytic copper foil of the present embodiment in a scanning electron microscope (SEM).

Figure 4 is a photograph of a focused ion beam (FIB) of an electrolytic copper foil of the presently-created embodiment.

Fig. 5A is a cross-sectional view showing the circuit board assembly of the present embodiment.

Figure 5B shows a partial enlarged view of the circuit board assembly of Figure 5A in region VB.

Figure 6 is a cross-sectional view showing a circuit board assembly of another embodiment of the present invention.

The following is a description of an embodiment of the present disclosure relating to an "electrolytic copper foil having a pile-like structure and a wiring board assembly" disclosed in the present specification by a specific embodiment. The electrolytic copper foil having a fluff-like structure provided in the present embodiment can be applied to a printed circuit board (PCB) or a flexible printed circuit board (FPC).

Please refer to FIG. 1 and FIG. 2 . 1 is a partial cross-sectional view showing an electrolytic copper foil of the present embodiment, and FIG. 2 is a partial enlarged view of the electrolytic copper foil of FIG. 1 in a region II. The surface layer of the electrolytic copper foil 1 of the present embodiment has a pile-like structure. In detail, the electrolytic copper foil 1 of the present embodiment includes a green foil layer 10 and a surface treatment layer 11 on the green foil layer 10.

It should be noted that the green foil layer 10 is formed by an electroplating process, and the green foil layer 10 has a smooth surface 10a and a rough surface 10b opposite to the smooth surface 10a. The smooth surface 10a generally refers to the side of the green foil layer 10 that contacts the cathode wheel (not shown) during the plating process, and the rough surface 10b is the surface where the green foil layer 10 contacts the electrolyte.

After the process of the green foil layer 10 is completed, the rough surface 10b or the smooth surface 10a of the green foil layer is subjected to surface treatment, and the surface treatment layer 11 is formed on the rough surface 10b or the smooth surface 10a. In one embodiment, the total thickness T of the electrolytic copper foil 1 is between 6 and 400 μm, depending on the needs of the actual application. The foregoing surface treatment includes a plurality of roughening treatments and curing treatments so that the surface layer of the electrolytic copper foil 1 has a pile structure. The roughening treatment and the curing treatment mean that the raw foil layer 10 is placed in a battery having copper ions and sulfate ions. Electroplating is performed in the solution to deposit copper atoms on the rough surface 10b or the smooth surface 10a of the green foil layer 10 to form a plurality of copper tumors. The shape of the copper tumor can be adjusted by controlling the composition of the electrolyte, such as the concentration of copper ions, the concentration of sulfuric acid or the composition of the additive, or the magnitude of the current density.

For example, the plating solution contains a relatively low concentration of copper, which limits the crystal growth direction of the knob-like copper particles. Further, the concentration of arsenic oxide and the concentration of tungstate ions do not exceed 20 ppm. If the concentration of arsenic oxide or the concentration of tungstate ions is too high, a spherical copper tumor having a large size may be formed, and it is difficult to form a copper tumor resembling a fluff or a villus.

In a preferred embodiment, the concentration of copper in the plating solution is between 3 and 40 g/L, the concentration of sulfuric acid is between 100 and 120 g/L, the concentration of arsenic oxide is not more than 20 ppm, and the concentration of tungstate ions (WO ₄ ^2- ) is At 5 to 20 ppm. Controlling the current density to be 15 to 40 A/dm ² and controlling the time of the roughening treatment so that the copper grows in a direction substantially perpendicular to the rough surface 10b or the smooth surface 10a of the green foil layer 10 upon crystallization, while limiting the copper level The direction grows and controls the size and shape of the copper. According to this, the surface treatment layer 11 located on the rough surface 10b or the smooth surface 10a of the green foil layer 10 can have a plurality of fluffy copper tumors 110.

In detail, as shown in FIG. 2, in the present embodiment, the surface treatment layer 11 includes a plurality of pile-like copper tumors 110, and each of the pile-like copper tumors 110 is along the rough surface 10b or the smooth surface 10a. Parallel to the long axis direction.

In addition, each of the fluffy copper tumors 110 has a maximum major axis diameter D1 and a maximum minor axis diameter D2. In an embodiment, the largest major axis diameter D1 is between 0.5 μm and 1.5 μm, and the largest minor axis diameter D2 is between 0.1 μm and 1.0 μm. In addition, a fluffy accommodating space S1 is formed between each two adjacent fluffy copper tumors 110.

It should be noted that the surface layer of the existing electrolytic copper foil has a plurality of spherical copper tumors, and the spherical copper tumors have substantially the same size in any direction and are densely distributed. In contrast, the plurality of pile-like copper tumors 110 of the electrolytic copper foil 1 of the present embodiment are in the short-axis direction (that is, parallel to the rough surface 10b or the smooth surface 10a of the green foil layer 10). The diameter on the arrow is smaller than the diameter in the long axis direction. In a preferred embodiment, the ratio of the largest minor axis diameter D2 of the fluffy copper tumor 110 to the largest major axis diameter D1 is between 0.2 and 0.7.

In the present embodiment, the largest major axis diameter D1 of the villous copper tumor 110 is not larger than the diameter of the existing spherical copper tumor. Therefore, the surface roughness of the electrolytic copper foil 1 in the present embodiment is not greatly increased due to the change in the shape of the copper tumor. In an embodiment, the thickness t of the surface treatment layer 11 is approximately between 0.1 and 4 μm, and the surface roughness of the surface treatment layer 11 is approximately between 1 and 4 μm. Accordingly, the electrolytic copper foil 1 of the present embodiment can be applied to a high frequency substrate to transmit a high frequency signal.

On the other hand, in the electrolytic copper foil 1 of the present embodiment, the pitch P1 between every two adjacent fluffy copper tumors 110 is also wide. In other words, the fluffy copper tumor 110 of the presently-created embodiment also has a lower density. In one embodiment, the pitch P1 between every two adjacent fluffy copper tumors 110 is between 0.1 and 0.4 μm, and the distribution density of these fluffy copper tumors 110 is 2 to 5 per square micron. .

Referring to FIG. 3 and FIG. 4, respectively, a scanning electron microscope (SEM) of the electrolytic copper foil of the present embodiment is shown by Focused ion beam and electron beam system (FIB/SEM). Photo and photo of the focused ion beam (FIB). Fig. 3 shows a partial plan view of the electrolytic copper foil of the presently-created embodiment, and Fig. 4 shows a partial cross section of the electrolytic copper foil of the presently-created embodiment.

From the photographs of Figs. 3 and 4, it can be confirmed that the electrolytic copper foil of the present embodiment forms a plurality of fluffy copper tumors instead of spherical copper tumors after surface treatment. In addition, the electrolytic copper foil 1 of the present embodiment is analyzed by a focused ion beam and an electron beam microscopy system, and the copper crystal grain size of the electrolytic copper foil is between 2.5 and 6.0 μm in the long axis direction, and on the short axis. The size of the direction is between 0.2 μm and 2.0 μm.

In addition, after the roughening and solidification treatment of the electrolytic copper foil 1 of the present embodiment, other subsequent treatments may be performed to adjust the heat resistance or resistance of the electrolytic copper foil 1. Corrosiveness, which is, for example, one of heat and chemical resistance treatment, chromate treatment, silane coupling treatment, and combinations thereof, can be selected according to actual needs by those skilled in the art.

Please refer to FIG. 5A and FIG. 5B. Fig. 5A is a cross-sectional view showing the circuit board assembly of the present embodiment. Figure 5B shows a partial enlarged view of the circuit board assembly of Figure 5A in region VB. The electrolytic copper foil of the present embodiment can be applied to different circuit board assemblies 2 such as a rigid printed circuit board (PCB), a flexible printed circuit board (FPC), and the like, but the present invention is not limited thereto.

In the embodiment of FIG. 5A, the circuit board assembly 2 includes a substrate 20, a wiring layer 21, and an adhesive layer 22 connected between the substrate 20 and the wiring layer 21. The wiring layer 21 may be an electrolytic copper foil 1 directly as described above or an electric circuit formed by etching the above-described electrolytic copper foil 1.

The substrate 20 may be a high frequency substrate such as an epoxy resin substrate, a polyoxyxylene resin substrate (PPO) or a fluorine resin substrate, or a polyimide, an ethylene terephthalate or a polycarbonate. A substrate composed of a liquid crystal polymer or a material such as polytetrafluoroethylene.

Referring to FIG. 5B, similar to the embodiment of FIG. 2, the wiring layer 21 of the presently-created embodiment includes a surface treatment layer 211 having a plurality of fluffy copper tumors 211a. When the wiring layer 21 and the substrate 20 are bonded by the adhesive layer 22, the surface treatment layer 11 faces the adhesive layer 22 and is bonded to the substrate 20, and the adhesive layer 22 is filled in the gap between the fluffy copper tumors 211a, that is, The inside of the fluffy accommodation space S1 is filled.

Please refer to FIG. 6, which shows a cross-sectional view of a circuit board assembly of another embodiment of the present invention. The wiring board assembly 2' of this embodiment includes a substrate 20 and a wiring layer 21. Similar to the embodiment of Fig. 5A, the wiring layer 21 may be the above-described electrolytic copper foil 1, or an electric circuit formed by etching the above-described electrolytic copper foil 1.

Unlike the embodiment of FIG. 5A, in the present embodiment, the substrate 20 can be directly bonded to the wiring layer 21 by hot pressing without additionally bonding the electrolytic copper foil 1 through the adhesive layer 22. In the present embodiment, the substrate 20 may be made of a material such as a liquid crystal polymer or a glass fiber substrate (Pre-preg). Therefore, when performing the pressing, a part of the substrate 20 The fraction is filled in the space between the fluffy copper tumors 211a, that is, into the pile-like accommodation space S1.

Compared with the existing spherical copper tumor, in the present embodiment, the size of the fluffy copper tumor 211a is small in the horizontal direction, and the spacing between the two adjacent fluffy copper tumors 211a is wide, and the adhesion can be made. Layer 22 or substrate 20 may coat most of the surface of each of the fluffy copper horns 211a during the lamination process. That is, the adhesive layer 22 or the substrate 20 and the pile-like copper tumor 211a of the wiring layer 21 of the present embodiment have a large contact area, so that the peeling strength of the wiring layer 21 can be improved. After testing, when the wiring layer 21 and the glass fiber board (FR4) of the present embodiment are pressed against each other, the peel strength is at least greater than 3.5 lb/in.

In summary, the creative effect of the present invention is that the electrolytic copper foil 1 having a fluff structure on the surface of the present invention has a low surface roughness, and thus can be applied to electrical components in different fields, and in particular, can be applied to require high transmission. The circuit board component of the frequency signal 2.

In addition, since the surface treatment layers 11, 211 of the electrolytic copper foil 1, 21 have a plurality of pile-like copper tumors 110, 211a, and a plurality of pile-like copper tumors 110, 211a and the substrate 20 or the adhesive layer 22 have a large The area is then increased to increase the adhesion between the electrolytic copper foil 1, 21 and the substrate 20 or the adhesive layer 22. In other words, by changing the shape of the copper tumors 110, 211a of the electrolytic copper foils 1, 21, the surface roughness of the electrolytic copper foil can meet the requirements of high-frequency transmission, and the peel strength of the electrolytic copper foil can be increased.

The above disclosure is only a preferred and feasible embodiment of the present invention, and is not intended to limit the scope of the patent application of the present invention. Therefore, any equivalent technical changes made by using the present specification and the contents of the drawings are included in the application for this creation. Within the scope of the patent.

10‧‧‧ Raw foil layer

11‧‧‧Surface treatment layer

110‧‧‧Fleece copper tumor

D1‧‧‧Maximum long shaft diameter

D2‧‧‧Maximum short shaft diameter

S1‧‧‧Flour-like accommodation space

P1‧‧‧ spacing

t‧‧‧Surface treatment layer thickness

Claims (10)

An electrolytic copper foil having a fluff-like structure comprising a green foil layer and a surface treatment layer on the green foil layer, the surface treatment layer comprising a plurality of fluffy copper tumors, wherein each of the fluff The copper tumor has a largest major axis diameter and a maximum minor axis diameter, the largest major axis diameter being between 0.5 μm and 1.5 μm, and the largest minor axis diameter being between 0.1 μm and 1.0 μm A fluffy accommodation space is formed between each of the two adjacent fluffy copper tumors. The surface layer according to claim 1 has an electrolytic copper foil having a pile-like structure, wherein a ratio of the largest minor axis diameter to the largest major axis diameter is between 0.2 and 0.7. The surface layer according to claim 1 has an electrolytic copper foil having a pile-like structure, wherein a plurality of said pile-like copper tumors have a distribution density of 2 to 5 per square micrometer. The surface layer according to claim 1 has an electrolytic copper foil having a pile-like structure, wherein a spacing between every two adjacent said pile-like copper tumors is between 0.1 and 0.4 μm. The surface layer according to claim 1 has an electrolytic copper foil having a pile-like structure, wherein the thickness of the electrolytic copper foil is between 6 and 400 μm, and the thickness of the surface treatment layer is between 0.1 and 4 μm. And a surface roughness of the surface treatment layer is between 1 and 4 μm. The surface layer according to claim 1 has an electrolytic copper foil having a pile-like structure, wherein the green foil layer has a smooth surface and a rough surface opposite to the smooth surface, and the surface treatment layer is located on the rough surface Or the smooth surface, and each of the fluffy copper tumors extends along a long axis direction that is not parallel to the rough surface or the smooth surface. A circuit board assembly comprising a substrate, at least one circuit layer on the substrate, and an adhesive layer connected between the substrate and the circuit layer, wherein the circuit layer The layer is an electrolytic copper foil having a pile-like structure as described in one of claims 1 to 6, and the adhesive layer is filled in the pile-like accommodation space. The circuit board assembly of claim 7, wherein the circuit board assembly is a rigid printed circuit board or a flexible printed circuit board. The circuit board assembly according to claim 7, wherein the substrate is a high frequency substrate, and the high frequency substrate is an epoxy resin substrate, a polyoxyxylene resin substrate or a fluorine resin substrate. A circuit board assembly comprising a substrate and at least one wiring layer on the substrate, wherein the wiring layer has a fluff like the surface layer of one of claims 1 to 6 An electrolytic copper foil of a structure, and a part of the substrate is filled in the pile-like accommodation space.