TWI619852B - Manufacturing methods of electrolytic copper foil having football-shaped copper particles and circuit board assembly - Google Patents

Abstract

The invention discloses a method for manufacturing an electrolytic copper foil and a circuit board assembly having a football-like copper knob. A method for manufacturing an electrolytic copper foil having an approximately rugby-shaped copper knob includes forming a green foil layer by an electrolytic method, and the green foil layer has a predetermined surface. Next, a roughened layer is formed on a predetermined surface of the green foil layer, so as to form an electrolytic copper foil having a surface with approximately a rugby protrusion. The roughening treatment layer includes a plurality of rugby-shaped copper knobs, and an approximately funnel-shaped accommodation space is formed between every two adjacent rugby-shaped copper knobs. The step of forming the roughening treatment layer further includes: performing a first plating roughening treatment and performing a first plating curing treatment, wherein a first plating solution used in the first plating roughening treatment contains 3 To 40 g / L of copper, 100 to 120 g / L of sulfuric acid, arsenic oxide not exceeding 20 ppm, and 5 to 20 ppm of tungstate ion. Thereby, since the electrolytic copper foil having a rugby-like copper knob on the surface layer has a larger contact area with the resin substrate, it can have higher peel strength.

Description

Method for manufacturing electrolytic copper foil and circuit board assembly with approximate football-like copper knob

The invention relates to a method for manufacturing an electrolytic copper foil and a circuit board assembly, in particular to a method for manufacturing an electrolytic copper foil having a plurality of approximately rugby-like copper knobs on its surface layer, and an electrolytic method using the surface layer having a plurality of rugby-like copper knobs Manufacturing method of copper foil circuit board assembly.

The existing copper foil applied to the printed circuit board will be formed on the cathode wheel by electroplating, and then made through the post-processing to form the final product. The post-processing includes roughening the rough surface of the original foil to form a plurality of spherical copper nodules 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 peeling strength of the copper foil. .

However, in recent years, electronic products tend to be high-frequency and high-speed. When transmitting high-frequency signals, the shape of the surface of the copper foil has a great influence on transmission loss. Copper foils with large surface roughness have a longer signal propagation distance, which can cause signal attenuation or delay. In other words, the smoother the surface of the copper foil, the less the signal will lose during transmission. Therefore, the flatness of the copper foil surface plays a very important role.

Please refer to FIG. 1, which is a schematic partial cross-sectional view of a copper foil in the prior art. As shown in FIG. 1, in the prior art, a plurality of copper bumps F10 formed on the surface of the copper foil F1 are approximately spherical, and most of the spherical copper bumps F10 have a maximum size in the horizontal direction larger than in the vertical direction. The largest dimension in the direction. In this way, although the thickness of the copper foil can be made The roughness is low to meet the needs of high-frequency transmission, but when the copper foil is bonded to a high-frequency substrate, the bonding strength of the copper foil and the high-frequency substrate is insufficient.

If you try to reduce the roughness of the copper foil surface to reduce high-frequency signal transmission loss, the peel strength of the copper foil and the circuit board will be reduced. Therefore, how to improve the peel strength of the copper foil while maintaining the flatness of the surface of the copper foil at the same time is a major issue for researchers in the industry.

The technical problem to be solved by the present invention is to provide an electrolytic copper foil with a football-like copper knob and a method for manufacturing a circuit board assembly in response to the shortcomings of the prior art.

One of the technical solutions adopted by the present invention is to provide a method for manufacturing an electrolytic copper foil with a football-like copper knob. A method for manufacturing an electrolytic copper foil having an approximately rugby-shaped copper knob includes forming a green foil layer by an electrolytic method, and the green foil layer has a predetermined surface. Next, a roughened layer is formed on a predetermined surface of the green foil layer, so as to form an electrolytic copper foil having a surface with approximately a rugby protrusion. The roughening treatment layer includes a plurality of approximately rugby-shaped copper knobs, and an approximately funnel-shaped accommodation space is formed between every two adjacent approximately rugby-shaped copper knobs. The step of forming the roughening treatment layer further includes: performing a first plating roughening treatment and performing a first plating curing treatment, wherein a first plating solution used in the first plating roughening treatment contains 3 To 40 g / L of copper, 100 to 120 g / L of sulfuric acid, arsenic oxide not exceeding 20 ppm, and 5 to 20 ppm of tungstate ion.

Another technical solution adopted by the present invention is to provide a method for manufacturing a circuit board assembly, which provides an electrolytic copper foil having a football-like copper knob formed by the above manufacturing method. Next, the above-mentioned electrolytic copper foil with a rugby-like copper knob is pressed face-to-face with a resin substrate to form a circuit board assembly, wherein the electrolytic copper foil with a rugby-like copper knob is used to roughen the resin with a roughened surface Substrate.

The beneficial effect of the present invention is that, by the above-mentioned manufacturing method, electrolysis can be made The roughened layer of the copper foil has a plurality of rugby-shaped copper knobs or approximately rugby-shaped copper knobs. That is, the width of a rugby-shaped copper knob or an approximately rugby-shaped copper knob is smaller than the width of a spherical copper-shaped knob in the prior art. Therefore, when the electrolytic copper foil having a rugby-like copper knob on the surface layer and the resin substrate are bonded, the electrolytic copper foil having a rugby-like copper knob on the surface layer is compared with the electrolytic copper foil having a spherical copper knob in the prior art. It has a larger contact area with the resin substrate, so that it can have higher peel strength.

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

F1‧‧‧ Existing copper foil

F10‧‧‧Spherical copper tumor

1‧‧‧ raw foil device

10‧‧‧ electrolytic cell

11‧‧‧Anode plate

12‧‧‧ cathode wheel

13‧‧‧roller

L0‧‧‧ electrolyte

14‧‧‧ Diversion tube

E1‧‧‧Power Supply Unit

2‧‧‧ surface treatment device

20‧‧‧Transfer Unit

21‧‧‧Roughening unit

L1‧‧‧The first plating solution

210‧‧‧ roughening tank

211‧‧‧roughened anode plate

22‧‧‧curing unit

L2‧‧‧Second plating solution

220‧‧‧curing tank

221‧‧‧cured anode plate

23‧‧‧cleaning tank

3‧‧‧ electrolytic copper foil

T‧‧‧Total thickness

30‧‧‧ raw foil

30a‧‧‧Rough surface

30b‧‧‧ smooth surface

31‧‧‧Coarse treatment layer

310‧‧‧ Copper Tumor

D1‧‧‧Maximum major axis diameter

D2‧‧‧Maximum short axis diameter

S1‧‧‧Funnel-shaped accommodation space

t‧‧‧Roughened layer thickness

P1‧‧‧pitch

M1, M1’‧‧‧Circuit board components

4‧‧‧ resin substrate

5‧‧‧ Adhesive

S100, S200 ~ 204, S300‧‧‧Process steps

FIG. 1 is a schematic partial cross-sectional view of an electrolytic copper foil in the prior art.

FIG. 2 is a flowchart of a method for manufacturing an electrolytic copper foil with a football-like copper knob on its surface layer according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of a system for performing a method for manufacturing an electrolytic copper foil having a rugby-like copper knob on the surface layer of FIG. 2.

FIG. 4 is a schematic partial cross-sectional view of an electrolytic copper foil having an approximately rugby-like copper knob on its surface layer according to an embodiment of the present invention.

FIG. 5 is a partially enlarged schematic view of the electrolytic copper foil with an approximately rugby-shaped copper knob on the surface layer in FIG. 4 in a region V. FIG.

FIG. 6 is a scanning electron microscope (SEM) photograph of an electrolytic copper foil with an approximately rugby-like copper knob on its surface layer according to an embodiment of the present invention.

FIG. 7 is a scanning electron microscope (SEM) photograph of an electrolytic copper foil of a comparative example.

FIG. 8 is a focused ion beam (FIB) photograph of an electrolytic copper foil with an approximately rugby-like copper knob on the surface of an embodiment of the present invention.

FIG. 9 is a schematic cross-sectional view of a circuit board assembly according to an embodiment of the present invention.

FIG. 10 is a partial enlarged view of the circuit board assembly of FIG. 9 in an area X. FIG.

FIG. 11 is a schematic cross-sectional view of a circuit board assembly according to another embodiment of the present invention.

The following is a specific embodiment to explain the embodiment of the "manufacturing method of an electrolytic copper foil and a circuit board assembly with a rugby-like copper knob on the surface layer" disclosed by the present invention. The method for manufacturing an electrolytic copper foil with a rugby-like copper knob provided by an embodiment of the present invention can obtain an electrolytic copper foil having a low thickness and a high peeling strength. In addition, the circuit board assembly formed by bonding the electrolytic copper foil and the resin substrate with a rugby-like copper knob on the surface layer manufactured by the aforementioned method can be applied to high-frequency signal transmission.

Please refer to FIG. 2 and FIG. 3. FIG. 2 shows a flowchart of a method for manufacturing an electrolytic copper foil with a rugby-like copper knob on the surface layer according to an embodiment of the present invention. FIG. Equipment schematic.

First, as shown in FIG. 2, in step S100, a green foil layer is formed by an electrolytic method, wherein the green foil layer has a predetermined surface.

Referring to FIG. 3, the step of forming a green foil layer by an electrolytic method includes providing a green foil device 1. The green foil device 1 includes at least an electrolytic cell 10, an anode plate 11, a cathode wheel 12, and a roller 13.

As mentioned above, the electrolytic cell 10 is used for containing the electrolyte L0. The anode plate 11 is disposed in the electrolytic cell 10 and is electrically connected to a positive output terminal of a power supply device 2. The anode plate 11 is formed by coating a titanium plate with an iridium element or an oxide thereof. The cathode wheel 12 is disposed corresponding to the electrolytic cell 10 and is located above the anode plate 11. In addition, the cathode wheel 12 is electrically connected to a negative output terminal of the power supply device 2. In the embodiment of the present invention, the cathode wheel 12 is a titanium roller.

In addition, in this embodiment, the green foil device 1 further includes a deflector 14 in fluid communication with the electrolytic cell 10. The aforementioned electrolytic solution L0 is injected into the electrolytic cell 10 through the guide tube 14 to flood the anode plate 11 and immerse part of the cathode wheel 12 in the electrolytic solution L0.

Next, as shown in FIG. 3, the power supply device E1 outputs a direct current to the anode plate 11 and the cathode wheel 12, thereby applying a current to the electrolytic solution L0, so that copper ions in the electrolytic solution L0 are precipitated on the surface of the cathode wheel 12, thereby forming Foil layer 30.

In addition, when the green foil layer 30 is formed by the electrolytic electrolytic solution L0, the electrolytic solution L0 is continuously supplied into the electrolytic tank 10. Specifically, the electrolytic solution L0 can flow into the electrolytic cell 10 through the guide tube 14 to maintain the copper ion concentration of the electrolytic solution L0 in the electrolytic cell 10. Please refer to FIG. 3 again, the green foil layer 30 formed on the surface of the cathode wheel 12 will be peeled off from the surface of the cathode wheel 12 and passed through the roller 13 for subsequent processes.

Furthermore, the green foil layer 30 has a rough surface 30a and a smooth surface 30b opposite to the aforementioned rough surface 30a. The smooth surface 30b is the surface where the green foil layer 30 and the cathode wheel 12 are in contact during the electrolysis process, so it is smooth. The roughness of the surface 30b is relatively constant. The rough surface 30a is a surface that contacts the electrolytic solution L0. The rough surface 30a or the smooth surface 30b of the green foil layer 30 usually has a plurality of granular protrusions. In one embodiment, the ten-point average roughness of the rough surface 30a of the green foil layer 30 does not exceed 2 μm, for example, between 0.9 μm and 1.9 μm.

Next, referring to FIG. 2 again, in step S200, a roughening treatment layer is formed on a predetermined surface of the green foil layer to form an electrolytic copper foil having a surface layer with approximately rugby-like protrusions. The roughening treatment layer includes A plurality of approximately rugby-shaped copper knobs, and an approximately funnel-shaped accommodation space is formed between every two adjacent approximately rugby-shaped copper knobs.

As described above, the step S200 of forming a roughening treatment layer further includes performing at least one plating roughening treatment and at least one plating curing treatment. In the embodiment of the present invention, the green foil layer is subjected to two electroplating roughening treatments and two electroplating curing treatments to form a roughening treatment layer on a predetermined surface of the green foil layer, where the predetermined surface may refer to a rough surface or a smooth surface. At least one of them.

In detail, as shown in FIG. 2, in one embodiment, after step S100, the first plating roughening process (step S201), the first plating curing process (step S203), and the first step are sequentially performed. The second plating roughening process (step S202) and the second plating curing process (step S204).

In another embodiment, after step S100, the first plating roughening process (step S201), the second plating roughening process (step S202), the first The secondary plating curing process (step S203) and the second plating curing process (step S204).

Furthermore, as the number of times of roughening treatment and electroplating and curing treatment increases, the bonding strength between the electrolytic copper foil and the resin substrate can be increased, but the surface roughness of the electrolytic copper foil is also increased, which is unfavorable for application in High-frequency signal transmission. Therefore, the number of electroplating roughening treatments and electroplating curing treatments and the adjustment order can be increased or decreased according to the needs of the actual manufacturing process.

Please refer to Figure 3. The description will be made by taking the first plating roughening process, the first plating curing process, the second plating roughening process, and the second plating curing process in this order as an example.

As shown in FIG. 3, the surface treatment device 2 for performing steps S201 to S204 includes a plurality of transfer units 20, at least one roughening unit 21 (two are shown in FIG. 3), and at least one curing unit arranged on a production line. There are two units 22 (two shown in FIG. 3) and a plurality of cleaning tanks 23. The number of the roughening unit 21, the curing unit 22 and the cleaning tank 23 is set according to actual needs. The plurality of transfer units 20 transfer the green foil layer 30 to the roughening unit 21, the cleaning tank 23, and the curing unit 22 for processing according to a preset process.

The roughening unit 21 includes a roughening tank 210 for supporting the first plating solution L1 and a set of roughening anode plates 211 provided in the roughening tank 210. As shown in FIG. 3, when the first plating roughening process is performed, the green foil layer 30 is put into the roughening tank 210 on which the first plating solution L1 is loaded. The first plating solution L1 used in the embodiment of the present invention contains 3 to 40 g / L of copper, 100 to 120 g / L of sulfuric acid, not more than 20 ppm of arsenic oxide (As ₂ O ₃ ), and 5 to 20 ppm of tungstate ion (WO ₄ ^2- ).

When the first electroplating roughening process is performed, a positive voltage and a negative voltage are applied to the roughened anode plate 211 and the green foil layer 30, respectively, so that copper ions in the first plating solution L1 are reduced, and the green foil layer is reduced. The rough surface 30a of 30 forms a plurality of nodular copper particles.

It should be noted that the first plating solution L1 used in the embodiment of the present invention has a special composition, which can limit the crystal growth direction of the nodular copper particles. In addition, the concentration of arsenic oxide and the concentration of tungstate ions do not exceed 20 ppm. If the concentration of arsenic oxide is too high, a large-sized spherical copper tumor may be formed, and it is difficult to form an approximate olive Spherical or rugby-shaped copper knobs.

Further, when the first electroplating roughening process is performed, because the copper concentration in the first plating solution L1 is low (less than 40 g / L), copper atoms can only be selected along the preferred crystallization direction (i.e. Portrait). In other words, the nodular copper particles prefer to grow in a direction substantially perpendicular to the rough surface 30 a of the green foil layer 30, but less likely to grow in a direction substantially parallel to the rough surface 30 a of the green foil layer 30. Therefore, the growth degree of the nodular copper particles in the horizontal direction is limited, so that the nodular copper particles have a rugby shape standing upright on the rough surface 10 b or the smooth surface 10 a of the green foil layer 10.

Therefore, after the first electroplating and roughening treatment, most of the nodular copper particles formed on the rough surface 30a of the green foil layer 30 in the horizontal direction will be smaller than those in the vertical direction, and every two phases The spacing between adjacent nodular copper particles is wide.

In addition, in one embodiment, when the first electroplating roughening process is performed, the current density of the roughened anode plate 211 is between 40 and 80 A / dm ² , so that nodular copper particles having an approximately rugby shape can be formed. In addition, when the first plating roughening process is performed, the temperature of the first plating solution is maintained approximately at 20 to 40 degrees Celsius.

After the first electroplating roughening process is completed, the first electroplating curing process is performed to form a copper protective layer covering the nodular copper particles, so that the nodular copper particles are tightly fixed to the rough surface 30a of the green foil layer 30 Or smooth surface 30b to prevent the "falling powder" phenomenon.

As shown in FIG. 3, the first plating curing process is performed by the curing unit 22. The curing unit 22 includes a curing tank 220 for carrying the second plating solution L2 and a set of curing anode plates 221 disposed in the curing tank 220.

In this embodiment, after the first electroplating and roughening treatment is performed on the raw foil layer 30 in the roughening tank 210, the green foil layer 30 is first transferred to the cleaning tank 23 through the transfer unit 20, and then is transferred to the curing tank 220 to perform the first time. Electroplating and curing.

When the first electroplating and curing process is performed, a positive voltage and a negative voltage are applied to the solidified anode plate 221 and the green foil layer 30, respectively, so that the copper ions in the second plating solution L2 are reduced, and the green foil layer 30 is A copper protective layer is formed covering the nodular copper particles.

The second plating solution L2 used when performing the first plating curing process contains The copper of 50 to 70 g / L, sulfuric acid of 70 to 100 g / L, and arsenic oxide below 30 ppm, and the temperature of the second plating solution L2 is maintained at about 50 to 70 degrees Celsius.

It should be noted that the height of the nodular copper particles formed in the first plating roughening process is not high. If a thicker copper protective layer is formed during the first electroplating and curing process, although the probability of powder loss and the roughness of the surface of the electrolytic copper foil can be reduced, it is possible to reduce the adhesion of the electrolytic copper foil to the resin substrate. Surface area, which reduces peel strength. Therefore, when performing the first electroplating and curing process, the current density needs to be specially adjusted to form a thinner copper protective layer with better deep plating effect. Accordingly, it is possible to prevent the powder from falling off without reducing the surface area to which the electrolytic copper foil can adhere to the resin substrate. In one embodiment, in performing the first plating curing process, the current density is 15 to 40 A / dm ² .

In one embodiment, after performing the first electroplating roughening treatment and the first electroplating curing treatment, an electrolytic copper foil having a rugby-like protrusion or a rugby-like protrusion on the surface layer can be formed. The detailed structure of the roughening treatment layer will be further explained later.

Next, the green foil layer 30 that has undergone the first electroplating and curing treatment is transferred from the curing tank 220 to the cleaning tank 23 through the transfer unit 20, and then transferred to the next roughening tank 210 for the second plating. Roughening.

In this embodiment, the parameters of the second plating roughening process are approximately the same as the composition of the first plating solution L1 of the first plating roughening process. However, the current density used in the second plating roughening treatment is 50 to 90 A / dm ² , which is higher than the current density in the first plating roughening treatment. In this way, a plurality of nodular copper particles that have been formed on the rough surface 30 a of the green foil layer 30 can continue to grow. In addition, since the second plating roughening treatment is performed, the same first plating solution L1 as the first plating roughening treatment is used. Therefore, the growth direction of the nodular copper particles is still limited to a direction substantially perpendicular to the rough surface 30 a of the green foil layer 30. In this way, the bonding area between the final electrolytic copper foil and the resin substrate can be further increased.

Subsequently, the green foil layer 30 subjected to the second electroplating and roughening treatment is transferred from the roughening tank 210 to another cleaning tank 23 through the transfer unit 20, and then transferred to another curing tank 220 for the second time. Sub-plating curing treatment. The composition of the second plating solution L2 in the second plating and curing process may be the same as the composition of the second plating solution L2 in the first plating and curing process. In addition, the current density for performing the second plating curing process may be similar to that during the first plating curing process, which is about 15 to 40 A / dm ² . By performing the second electroplating and curing process, a copper protective layer can be further provided to avoid powdering.

Please refer to FIG. 4 and FIG. 5. FIG. 4 is a schematic partial cross-sectional view of an electrolytic copper foil according to an embodiment of the present invention. FIG. 5 is a partially enlarged schematic view of the electrolytic copper foil of FIG. 4 in a region V. FIG.

The surface of the electrolytic copper foil 3 manufactured by the manufacturing method of the said electrolytic copper foil has a rugby-like protrusion, and it can increase the area adjoining a resin substrate. In detail, the electrolytic copper foil 3 according to the embodiment of the present invention includes a green foil layer 30 and a roughening treatment layer 31 on the green foil layer 30.

The roughening treatment layer 31 is located on at least one of the rough surface 30 a and the smooth surface 30 b of the green foil layer 30. In the embodiment of FIG. 4, the roughening treatment layer 31 is located on the rough surface 30 a of the green foil layer 30. In one embodiment, the total thickness T of the electrolytic copper foil 3 is between 6 and 400 μm, which is determined according to actual application requirements.

As shown in FIG. 5, in the embodiment of the present invention, the roughening treatment layer 31 includes a plurality of rugby-shaped or approximately rugby-shaped copper knobs 310, and each of the rugby-shaped or approximately rugby-shaped copper knobs 310 is along and roughened. The surface 30a or the smooth surface 30b extends in a non-parallel major axis direction.

In addition, each rugby-shaped or approximately rugby-shaped copper knob 310 has a largest major axis diameter D1 and a largest minor axis diameter D2. In one embodiment, the maximum major axis diameter D1 is between 1.6 μm and 2.5 μm, and the largest minor axis diameter D2 is between 1.1 μm and 2.0 μm. In addition, an approximately funnel-shaped accommodation space S1 is formed between every two adjacent copper knobs 310.

Comparing FIG. 1 and FIG. 5, the size of the spherical copper tumors in the prior art in the short axis direction is larger than that in the long axis direction, and the distribution is dense. In contrast, Ben The diameter of a plurality of rugby-shaped or approximately rugby-shaped copper knobs 310 of the electrolytic copper foil 3 of the embodiment of the invention in the short axis direction (that is, a direction parallel to the rough surface 30a or the smooth surface 30b of the green foil layer 30) will be smaller than The diameter in the long axis direction is still small. In a preferred embodiment, the ratio of the largest short-axis diameter D2 to the largest long-axis diameter D1 of the rugby-shaped or approximately rugby-shaped copper knob 310 is between 0.3 and 0.8.

In the embodiment of the present invention, the largest major axis diameter D1 of the rugby-shaped or approximately rugby-shaped copper knob 310 is similar to the size of a conventional spherical copper knob in the vertical direction. Therefore, the surface roughness of the electrolytic copper foil 3 in the embodiment of the present invention does not increase significantly due to the shape change of the copper knob. In an embodiment, the thickness t of the roughening treatment layer 31 is approximately between 1.2 and 4 μm, and the ten-point average surface roughness (R _z ) of the roughening treatment layer 31 is approximately between 1 and 4 μm. . Accordingly, the electrolytic copper foil 3 according to the embodiment of the present invention can still be adapted to cooperate with a high-frequency substrate to transmit high-frequency signals.

On the other hand, in the electrolytic copper foil 3 according to the embodiment of the present invention, the pitch P1 between every two adjacent rugby-shaped or approximately rugby-shaped copper knobs 310 is also wide. In other words, the rugby-shaped or approximately rugby-shaped copper knob 310 of the embodiment of the present invention also has a lower density. In one embodiment, the distance P1 between two adjacent rugby-shaped or approximately rugby-shaped copper knobs 310 is between 0.5 and 1.8 μm. The distribution density is 0.5 to 1.7 particles per square micrometer.

Please refer to FIG. 6 and FIG. 7. FIG. 6 shows a scanning electron microscope (SEM) photograph of an electrolytic copper foil according to an example of the present invention, and FIG. 7 shows a scanning electron microscope photograph of an electrolytic copper foil of a comparative example. It is explained first that when the electrolytic copper foil of the comparative example is manufactured, the parameters when performing the plating roughening process are substantially the same as those of the embodiment of the present invention, but the composition of the plating solution used when performing the plating roughening process contains a concentration exceeding 40g / L of copper.

Comparing the photos of FIG. 6 and FIG. 7, it can be found that the copper knob particles of the electrolytic copper foil according to the embodiment of the present invention are smaller and have a longer shape. The copper knob shape of the electrolytic copper foil of the comparative example of FIG. 7 is spherical and coarser and denser.

Referring to FIG. 8, a photograph of a focused ion beam (FIB) of an electrolytic copper foil according to an embodiment of the present invention is taken through a focused ion beam and electron beam microscopy system. FIG. 8 also shows a partial cross-section view of an electrolytic copper foil according to an embodiment of the present invention.

From the photos of FIG. 6 and FIG. 8, it can be proved that, after the surface treatment of the electrolytic copper foil according to the embodiment of the present invention, a plurality of rugby-shaped copper knobs are formed instead of round copper-shaped copper knobs. In addition, the electrolytic copper foil of the embodiment of the present invention is analyzed by a focused ion beam and electron beam microscopy system. The copper crystal particle size of the electrolytic copper foil is between 1.2 and 4.0 μm.

Next, please refer to FIG. 2 again. In the embodiment of the present invention, in step S300, a surface treatment is performed. The aforementioned surface treatment may be at least one of an anti-heat treatment, an anti-oxidation treatment, and a silane coupling agent treatment.

When the surface treatment is heat-resistant, a zinc alloy heat-resistant layer is formed on the roughened layer by an electrolytic method, and the heat resistance of the electrolytic copper foil is increased. In one embodiment, the composition of the electrolyte used in performing the heat treatment includes 1 to 4 g / L of zinc and 0.3 to 2.0 g / L of nickel, and the current density used in performing the heat treatment is 0.4 to 2.5A / dm ² .

When the surface treatment is an anti-oxidation treatment, an anti-oxidation layer is formed on the roughened layer by an electrolytic method to increase the oxidation resistance of the electrolytic copper foil. The composition of the electrolytic solution used in performing the anti-oxidation treatment includes 1 to 4 g / L of chromium oxide and 5 to 20 g / L of sodium hydroxide, and the current density used in performing the anti-heat treatment is 0.3 to 3.0 A / dm ² .

When the surface treatment is a silane coupling treatment, a silane coupling agent treatment layer is formed on the roughening treatment layer, wherein 0.3 to 1.5% by weight of the silane coupling agent is used in performing the silane coupling treatment.

Please refer to FIG. 9 and FIG. 10. FIG. 9 is a schematic cross-sectional view of a circuit board assembly according to an embodiment of the present invention, and FIG. 10 is a partial enlarged view of the circuit board assembly of FIG. 9 in an area X. The electrolytic copper foil of the embodiment of the present invention can be applied to different circuit board components, such as a rigid printed circuit board (PCB), a flexible printed circuit board (FPC), and the like.

In the embodiment of FIG. 9, the circuit board assembly M1 is formed by a resin substrate 4 and the above-mentioned electrolytic copper foil 3 being pressed face to face, and the roughened layer 31 of the electrolytic copper foil 3 faces the resin substrate 4.

The resin substrate 4 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, ethylene terephthalate, polycarbonate Substrate made of materials such as liquid crystal polymer or polytetrafluoroethylene.

In the embodiments of FIGS. 9 and 10, the resin substrate 4 is a semi-cured substrate or a liquid crystal polymer substrate. It can be seen from FIG. 10 that, because the distance between the rugby-shaped or approximately rugby-shaped copper knobs 310 in the embodiment of the present invention is wide, the resin substrate 4 can be covered and laminated when the electrolytic copper foil 3 and the resin substrate 4 are pressed together. It contacts most of the surface of the rugby-shaped or approximately rugby-shaped copper knob 310 and can penetrate deep into the approximately funnel-shaped accommodation space S1. In this way, the bonding strength between the electrolytic copper foil 3 and the resin substrate 4 is enhanced.

Please refer to FIG. 11, which is a schematic cross-sectional view of a circuit board assembly according to another embodiment of the present invention. In this embodiment, the resin substrate 4 and the circuit layer 41 are combined by the adhesive 5, and a part of the adhesive 5 is filled into the approximately funnel-shaped accommodation space.

The electrolytic copper foil 3 and the resin substrate 4 according to the embodiment of the present invention are tested after being laminated, and the peel strength can be greater than 4 lb / in. Specifically, in an experimental example, the resin substrate 4 is a glass fiber board (FR4), and the glass fiber board (FR4) is laminated with the electrolytic copper foil of the embodiment of the present invention to form a laminated plate test piece. Next, it measured using the peel strength tensile machine. The test results show that the peel strength of the electrolytic copper foil is at least more than 7 lb / in.

In addition, the method for manufacturing a circuit board assembly according to the embodiment of the present invention may further include, after laminating the electrolytic copper foil 3 and the resin substrate 4, patterning the electrolytic copper foil 3 by etching to form a circuit layer.

In summary, the beneficial effect of the present invention is that in the method for manufacturing the electrolytic copper foil using the embodiment of the present invention, the concentration of copper can be reduced and the oxidation can be reduced by adjusting the composition of the first plating solution L1 in the plating roughening process. The content of arsenic and tungstate ions does not exceed 20ppm, so it can restrict the crystallization direction and growth direction of copper tumors, thereby forming a football Like or football-like copper knob 310.

Compared with the spherical copper knob F10 in the prior art, the lateral size of the rugby-shaped or approximately rugby-shaped copper knob 310 is smaller, which can increase the bonding surface area between the electrolytic copper foil 3 and the resin substrate 4. In addition, there is a wide distance between two adjacent rugby-shaped or approximately rugby-shaped copper knobs 310. When the resin substrate 4 and the electrolytic copper foil 3 are bonded, the resin substrate 4 can cover the entire surface of the copper knob and penetrate deeply. The space between two rugby-shaped or approximately rugby-shaped copper knobs 310 increases the adhesion between the electrolytic copper foil 3 and the resin substrate 4 or the adhesive layer 5.

In addition, since the size of the rugby-shaped or nearly rugby-shaped copper knob 310 of the electrolytic copper foil 3 of the embodiment of the present invention in the vertical direction is not larger than the size of the spherical copper knob F10 in the prior art in the vertical direction, The surface roughness of the electrolytic copper foil 3 is lower than that of the existing copper foil. However, the peeling strength of the electrolytic copper foil 3 according to the embodiment of the present invention does not decrease significantly due to the decrease in surface roughness, and meets the requirements of practical applications.

In addition, please refer to Table 1 below to show the surface roughness (Roughness), peel strength (Peel Strength), and the ratio of peel strength to surface roughness (P / R ratio) of the examples and comparative examples of the present invention, where the surface roughness The ten-point average roughness (Rz). The example is an electrolytic copper foil having a rugby-shaped copper knob, and the comparative example is an electrolytic copper foil having a round-shaped copper knob.

It can be seen from Table 1 that the surface roughness of the electrolytic copper foil of the embodiment of the present invention is lower than that of the comparative example (having a large-sized spherical copper nodules). Electrolytic copper foil can further reduce signal loss when applied to high-frequency transmission.

It should also be noted that the larger the ratio of peel strength to surface roughness, the greater the copper foil The smaller the peel strength affected by surface roughness, the better the performance of peel strength. As can be seen from the above table, compared with the comparative example, the ratio of the peeling strength to the surface roughness of the electrolytic copper foil of the embodiment of the present invention is larger. Therefore, the peeling strength of the electrolytic copper foil of the embodiment of the present invention is not excessively lost due to the low surface roughness.

The content disclosed above is only the preferred and feasible embodiment of the present invention, and therefore does not limit the scope of patent application of the present invention. Therefore, any equivalent technical changes made using the description and drawings of the present invention are included in the application of the present invention. Within the scope of the patent.

Claims (14)

A method for manufacturing an electrolytic copper foil having a rugby-like copper knob, comprising: forming a green foil layer by an electrolytic method, wherein the green foil layer has a predetermined surface; and forming a roughening treatment layer on the green foil layer. The predetermined surface of the green foil layer to form an electrolytic copper foil with a surface layer having approximately rugby-shaped protrusions, wherein the roughening treatment layer includes a plurality of approximately rugby-shaped copper knobs, and every two adjacent An approximately funnel-shaped accommodating space is formed between the approximately rugby-shaped copper knobs; wherein the step of forming the roughening treatment layer further includes: performing a first plating roughening treatment and performing a first plating A curing process, wherein a first plating solution used in the first electroplating roughening process contains 3 to 40 g / L of copper, 100 to 120 g / L of sulfuric acid, arsenic oxide not exceeding 20 ppm, and 5 to 20 ppm Tungstate ions; wherein the plurality of approximately rugby-shaped copper tumors have a largest major axis diameter and a largest minor axis diameter, the largest major axis diameter is between 1.6 μm and 2.5 μm, and the largest Shaft diameter Between 1.1μm to 2.0μm, the ratio between the maximum minor axis and major axis diameter and the maximum diameter of 0.3 to 0.8. The method of manufacturing an electrolytic copper foil having an approximately rugby-shaped copper knob according to claim 1, wherein a current density used when performing the first plating roughening treatment is 40 to 80 A / dm ² , and The predetermined surface is a rough surface or a smooth surface. The method of manufacturing an electrolytic copper foil having a rugby-like copper knob as described in claim 2, wherein the step of forming the roughening treatment layer further comprises: performing a second plating roughening treatment and performing a second Secondary plating curing process, the second plating roughening process uses the first plating solution, the current density used when performing the second plating roughening process is 50 to 90 A / dm ² , and the first The parameters of the secondary plating curing process are the same as those of the first plating curing process. The method of manufacturing an electrolytic copper foil having an approximately rugby-shaped copper knob according to claim 3, wherein the step of forming the roughening treatment layer is to sequentially perform the first plating roughening treatment, the first Secondary plating curing treatment, the second plating roughening treatment, and the second plating curing treatment. The method for manufacturing an electrolytic copper foil having an approximately rugby-shaped copper knob according to claim 3, wherein the step of forming the roughening treatment layer is to sequentially perform the first plating roughening treatment, the second The secondary plating roughening treatment, the first plating curing treatment, and the second plating curing treatment. The method for manufacturing an electrolytic copper foil having a rugby-like copper knob as described in claim 1, wherein a second plating solution used in performing the first plating curing treatment contains 50 to 70 g / L of Copper, 70 to 100 g / L of sulfuric acid, and arsenic oxide below 30 ppm, and the current density used when performing the first plating curing process is 15 to 40 A / dm ² . The method for manufacturing an electrolytic copper foil having an approximately rugby-shaped copper knob as described in claim 1, further comprising: performing an anti-heat treatment to form a zinc alloy heat-resistant layer on the roughening treatment layer, wherein The composition of the electrolyte used when performing the heat treatment includes 1 to 4 g / L of zinc and 0.3 to 2.0 g / L of nickel, and the current density used when performing the heat treatment is 0.4 to 2.5 A / dm ² . The method for manufacturing an electrolytic copper foil having an approximately rugby-shaped copper knob as described in claim 1, further comprising: performing an anti-oxidation treatment to form an anti-oxidation layer on the roughening treatment layer, wherein The composition of the electrolyte used in the anti-oxidation treatment includes 1 to 4 g / L of chromium oxide and 5 to 20 g / L of sodium hydroxide, and the current density used in performing the anti-heat treatment is 0.3 to 3.0 A / dm ² . The method for manufacturing an electrolytic copper foil having an approximately rugby-shaped copper knob as described in claim 1, further comprising: performing a silane coupling treatment to form a silane coupling agent treatment layer on the roughening treatment layer, wherein, In performing the silane coupling treatment, 0.3 to 1.5% by weight of a silane coupling agent is used. The method for manufacturing an electrolytic copper foil having approximately rugby-shaped copper knobs according to claim 1, wherein a plurality of said approximately rugby-shaped copper knobs have a distribution density of 0.5 to 1.7 per square micrometer, and every two phases The distance between the adjacent rugby-shaped copper knobs is between 0.5 and 1.8 μm. A method for manufacturing a circuit board assembly, comprising: providing the electrolytic copper foil having a rugby-like copper knob formed by the manufacturing method according to one of claims 1 to 11; The copper foil's electrolytic copper foil is pressed face to face with a resin substrate to form a circuit board assembly, wherein the roughening treatment layer faces the resin substrate. The method for manufacturing a circuit board assembly according to claim 11, wherein a peeling strength of the electrolytic copper foil having a football-like copper knob is at least greater than 53.57 kg / m. The method for manufacturing a circuit board assembly according to claim 11, wherein the electrolytic copper foil having a rugby-like copper knob and the resin substrate are combined by an adhesive, and a part of the adhesive is filled in the Inside an approximately funnel-shaped accommodation space. The method for manufacturing a circuit board assembly according to claim 11, wherein the resin substrate is a semi-cured substrate or a liquid crystal polymer substrate, and when the electrolytic copper foil having a football-like copper knob is pressed against the resin substrate When closed, a part of the resin substrate is filled into the approximately funnel-shaped accommodation space.