TWI817385B - Dual-sided conductive stacked structure and fabrication method thereof - Google Patents

Abstract

A dual-sided conductive stacked structure and fabrication method thereof are provided. The structure includes a substrate, a first conductive layer and a second conductive layer. The substrate has an upper surface and a lower surface opposite to the upper surface. At least one via hole is formed between the upper and the lower surface. The first conductive layer covers the upper, lower surfaces and sidewalls of the via hole. The second conductive layer covers the first conductive layer which is configured on the upper surface of the substrate as well as the first conductive layer which is configured on the lower surface of the substrate, such that the upper and lower surfaces of the substrate are electrically conductive. The present invention achieves to reduce the conventional process flow and cost. In addition, superior cleanliness in a drill process is maintained. Variability in a conventional chemical plating process is avoided as well.

Description

Double-sided conductive laminated structure and manufacturing method thereof

The present invention relates to a conductive structure of a transparent display device, in particular, a double-sided conductive laminated structure and a manufacturing method thereof that have a double-sided conductive layer and can save existing process steps and costs.

From its origin to the current high-density design, circuit boards are usually directly and closely related to silk screen printing or screen printing, so they are called printed circuit boards. In addition to the largest number of applications in circuit boards, other electronic industries include thick film hybrid circuits, chip resistors, and surface mounting solder paste printing. etc. also have their applications. Generally speaking, the function of a printed circuit board (PCB) is to provide a base for the first-level assembly of components to be joined with other necessary electronic circuit parts to form a module or finished product with specific functions. Therefore, PCB boards play an important role in integrating and connecting all functions of the entire electronic product; for example, PCB boards are currently used in transparent display devices and are combined with thick copper substrate manufacturing processes , thereby forming a double-sided conductive layer structure, as shown in Figures 1A to 1F.

Please refer to Figures 1A to 1F. First, the substrate 10 undergoes an appropriate cleaning (CLN) process. Then, as shown in Figure 1B, a sputtering process is used to create a thickness of approximately 0.1 on the surface of the substrate 10. Micron conductive layer 11, and then, as shown in Figure 1C, the plane is thickened through an electroplating process. The electroplating thickens the metal copper layer 12 with a thickness of about 8 to 16 microns, so that the thick copper reduces the Metal resistance. Subsequently, as shown in Figure 1D, a drilling process is performed on the structure to form a plurality of through holes 13 therein, and then an electroless plating process, also known as "electroless plating" is performed as shown in Figure 1E. "Electroless plating treatment" or "electroless plating treatment" to form an electroless metal plating layer 20 on the surface of the through holes 13, and, as shown in Figure 1F, the through holes 13 are connected through the electroless metal plating layer 20 , causing the front and reverse metal layers of the substrate 10 to become conductive. After completion, a second electroplating process is performed in Figure 1F to thicken the metal copper layer 12 to about 8 microns. After completing the above-mentioned processes, subsequent process steps such as lithography, etching, and printing are continued.

It is worth noting that in the existing process steps, before performing the sputtering process, in order to facilitate the adhesion of the subsequent metal conductive layer, a dielectric layer is generally sputtered on the surface of the substrate 10 . Please refer to Figure 2, which shows a schematic structural diagram of a dielectric layer in a thick copper substrate in the prior art. The material of the dielectric layer 22 can be, for example, nickel (Ni) or chromium (Cr), so that through The hole wall of the hole 13 presents a three-layer stacked structure (including: substrate 10/dielectric layer 22/metal copper layer 12). However, such a three-layer stacked structure usually causes many problems in the subsequent electroless plating process. For example, the problem of insufficient uniformity between the conductive layer and the non-conductive plating layer is often caused. Worse, please refer to As shown in FIG. 3 , the formed electroless metal layer 20 will have a serious lack of selectivity difference.

In addition, such a three-layer stacked structure (including: substrate/dielectric layer/metal copper layer) will also produce and form relatively large holes during the drilling process due to the characteristics of the multi-layer structure. Excessive slag and drill dirt will further affect the variation of the subsequent electroless plating process. Therefore, in view of these deficiencies, the inventor feels that the above deficiencies can be improved, and based on his years of relevant experience in this area, careful observation and research, and the application of academic theories, he proposes a novel design. The extremely innovative invention discloses an improved double-sided conductive laminated structure and a manufacturing method thereof. By using this improved double-sided conductive laminated structure and its manufacturing method, not only can the It solves the long-standing shortcomings of the existing technology, and can effectively eliminate and save the necessary steps and related process costs of the existing manufacturing process. Below, the applicant provides a detailed description of the specific structure and implementation of the invention.

In order to solve the problems existing in the prior art, one purpose of the present invention is to provide an innovative double-sided conductive laminated structure, which is an improvement on the current thick copper substrate structure. Compared with the existing technology, the present invention By using the chemical plating process to complete the conductive layers on the upper and lower surfaces of the substrate and the through holes, the conventional two process steps of sputtering layer and second electroplating layer can be omitted, effectively reducing the complexity of the process and its process cost.

Furthermore, another object of the present invention is to use this double-sided conductive laminated structure, which only contains a single material substrate before the drilling process. Therefore, when the subsequent chemical plating process is performed, due to The electroless plating process is directly electroless plating on a single material substrate, so there is no difference in conductor or layer structure as described in the prior art. This can naturally solve the uneven process or electroless plating thickness selectivity described in the prior art. problem.

What's more, another object of the present invention is to provide a double-sided conductive laminated structure and a manufacturing method thereof. Compared with the multi-layer structure (which has dielectric layers of different materials) used in the prior art, the method disclosed in the present invention is used. The technical solution is based on using only a single base material, which can reduce the generation of slag and drilling dirt during the subsequent drilling process, maintaining good cleanliness, controllable process, and high simplicity.

In addition, the double-sided conductive laminated structure and its manufacturing method disclosed in the present invention can also be combined with the manufacturing process of transparent display devices, so as to be further widely used in display products and their fields, thereby ensuring that it can enhance Industrial benefits and industrial applicability of the present invention.

In view of the above, the present invention mainly discloses a substrate using a single material, which is a double-sided conductive laminated structure, which includes: a substrate, a first conductive layer, and a second conductive layer. The base material has an upper surface and a lower surface opposite to the upper surface, and at least one through hole is formed between the upper surface and the lower surface of the base material. The first conductive layer covers the upper surface, the lower surface of the substrate, and the hole wall of the at least one through hole. The second conductive layer covers the first conductive layer located on the upper surface of the base material. At the same time, the second conductive layer also covers the first conductive layer located on the lower surface of the base material, so that the base material The upper surface and lower surface of the material provide electrical conduction.

According to an embodiment of the present invention, the substrate is made of a transparent or translucent material. The thickness of the substrate is greater than 25 microns. Moreover, the transmittance of the base material is greater than 80%.

According to an embodiment of the present invention, the first conductive layer is formed through an electroless plating process.

According to an embodiment of the present invention, the second conductive layer is formed through an electroplating process. In one embodiment, the second conductive layer is made of copper.

According to an embodiment of the present invention, the material of the first conductive layer is metal or an alloy thereof. In one embodiment, the first conductive layer is made of copper. The thickness of the first conductive layer may range from 0.3 to 3.0 microns, for example. Moreover, the uniformity of the first conductive layer is less than 20%.

In addition, according to many embodiments of the present invention, the through hole is not limited to its aperture shape. For example, the embodiments of the through hole include: circular holes, square holes, and rhombus holes. , inverted trapezoidal hole, trapezoidal hole, or through hole shape with irregular hole wall and other structures. As long as the present invention is equal and does not deviate from the inventive spirit of the present invention, those with ordinary knowledge in the art can adjust the application according to the actual process and needs, and it should still fall within the scope of the present invention.

According to an embodiment of the present invention, in order to increase the adhesion when covering the first conductive layer, the first conductive layer can further cover the upper surface, the lower surface of the substrate, and the contact surface of the hole wall of the at least one through hole. At least one microstructure is formed to increase the adhesion of the first conductive layer during adhesion through the at least one microstructure.

In one embodiment, the at least one microstructure may be in a zigzag shape, for example.

In one embodiment, the at least one microstructure may have a height difference between concave and convex.

The present invention is not limited by the distribution density or distribution pattern of these microstructures. Generally speaking, those with ordinary knowledge in the technical field can modify the modifications themselves based on the technical ideas taught by the present invention; however, as long as the present invention is equal and does not deviate from the spirit of the invention, it should still be subject to the present invention. Invention scope of invention.

On the other hand, the present invention also provides a method for manufacturing a double-sided conductive laminated structure, which includes the following steps: firstly providing a substrate having an upper surface and a lower surface opposite to the upper surface. Afterwards, at least one through hole is formed between the upper surface and the lower surface of the base material. After that, a first conductive layer is formed through an electroless plating process, and the first conductive layer covers the upper surface, the lower surface of the substrate, and the hole wall of the at least one through hole. A second conductive layer is then formed through an electroplating process, which covers the first conductive layer located on the upper surface of the base material. The second conductive layer also covers the first conductive layer located on the lower surface of the base material. layer, thereby providing electrical conduction between the upper surface and the lower surface of the substrate.

Therefore, based on the various diversified embodiments and implementation aspects disclosed above, it can be seen that the present invention mainly improves the existing substrate structure through the disclosed double-sided conductive laminated structure. , so that the electroless plating process can be directly electroplated on a substrate of a single material, thereby avoiding the differences in conductors or layer structures described in the prior art, thus solving the uneven or chemical process problems described in the prior art. The problem of plating thickness selectivity has indeed improved and solved various deficiencies exposed in the previous technology.

In the following implementation details, the applicant further explains in detail through specific embodiments in conjunction with the attached drawings, which will make it easier for those skilled in the art to understand the purpose, technical content, and characteristics of the present invention. and the results achieved.

The above description of the present invention and the following embodiments are used to demonstrate and explain the spirit and principles of the present invention, and to provide further explanation of the patent application scope of the present invention. Regarding the characteristics, implementation and effects of the present invention, the preferred embodiments are described in detail below with reference to the drawings.

Following the previous technology, the multi-layer structure used in the existing technology will be accompanied by serious problems such as slag and drilling dirt during the drilling process. At the same time, it will also cause uniformity during the electroless plating process. Poor and selective differences and other missing. Therefore, based on improving these deficiencies, the present invention proposes a better improved design to address these various problems, which is an innovative double-sided conductive laminated structure and its manufacturing method, in which only a single material substrate is used, and, The electroless plating process is used to simultaneously complete the conductive layer coverage on the upper and lower surfaces of the substrate and the through holes. Compared with the stacked structure with a dielectric layer in the prior art, the present invention has high controllability and simplicity, and has no process selectivity or no process. Equality is missing.

Please refer to FIG. 11 , which is a step flow chart of a manufacturing method of a double-sided conductive laminated structure according to an embodiment of the present invention. The manufacturing method mainly includes step S111, step S113, step S115, and step S117. In order to understand the technical solutions disclosed in the present invention in more detail, please also refer to the structures shown in Figures 4A to 4D, which are schematic structural diagrams corresponding to various processes according to embodiments of the present invention. As shown in step S111 of FIG. 4A and FIG. 11 , a substrate 40 is first provided, and an appropriate cleaning (CLN) process is performed on the substrate 40 . The base material 40 has an upper surface 411 and a lower surface 412 opposite to the upper surface 411 . According to embodiments of the present invention, the material of the base material 40 may be, but is not limited to, transparent or translucent materials, such as: polyester (PET), transparent polyimide (CPI), polyimide (Polyimide) , PI), polyvinylidene fluoride (PVDF), etc.

According to an embodiment of the present invention, the thickness of the base material 40 is greater than 25 microns, and the transmittance of the base material is greater than 80%.

After that, as shown in step S113 in Figure 4B and Figure 11 of the present invention, a drilling process is performed on the base material 40 to form at least one hole between the upper surface 411 and the lower surface 412 of the base material 40. The through hole 42 is formed between the upper surface 411 and the lower surface 412 of the base material 40 .

Thereafter, as shown in step S115 of FIG. 4C and FIG. 11 of the present invention, an electroless plating process is performed on the base material 40 to form a first conductive layer 50 . The first conductive layer 50 simultaneously covers the upper surface 411 and the lower surface 412 of the substrate 40 and the hole wall of the through hole 42 . According to an embodiment of the present invention, the first conductive layer 50 is formed through the electroless plating process. The material of the first conductive layer 50 is metal or its alloy. For example, the material of the first conductive layer 50 is copper. The thickness of the first conductive layer 50 is between 0.3 and 3.0 microns, and the uniformity of the first conductive layer is less than 20%.

Thereafter, as shown in step S117 of FIG. 4D and FIG. 11 of the present invention, an electroplating process is performed on the first conductive layer 50 to form a second conductive layer 60 . According to an embodiment of the present invention, the second conductive layer 60 formed covers the first conductive layer 50 located on the upper surface 411 of the substrate 40 , and the second conductive layer 60 also covers the first conductive layer 50 located on the lower surface 412 of the substrate 40 . The conductive layer 50 forms an electrical connection between the upper surface 411 and the lower surface 412 of the base material 40 . Thus, the double-sided conductive laminated structure 100 disclosed in the present invention is obtained. In the embodiment of the present invention, the second conductive layer 60 is formed through an electroplating process, and the material of the second conductive layer 60 is copper.

After completing the double-sided conductive laminated structure 100 disclosed in the present invention, processes such as photolithography, etching, and printing are continued. Generally speaking, those with ordinary knowledge in the technical field to which the present invention belongs can modify the modifications on their own under the technical ideas taught by the present invention; however, as long as the present invention is equal and does not deviate from the inventive spirit of the present invention, it is still possible to It should fall within the scope of the present invention.

Therefore, according to the technical solution disclosed in the present invention, it can be clearly seen that when performing the drilling process, the present invention only uses a single material substrate 40 without the dielectric layer used in the previous technology, so the simplicity can be controlled. At the same time, there is less slag and dirt generated when drilling. On the other hand, the present invention uses an electroless plating process to simultaneously complete the conductive layer covering of the upper surface 411, the lower surface 412 and the through holes 42 of the substrate 40. Compared with the stacked structure with a dielectric layer in the prior art, The present invention has high controllability and simplicity, and can also avoid the shortcomings of poor selectivity or unevenness in conventional manufacturing processes.

Please refer to Figure 5, which is a schematic diagram of a double-sided conductive laminated structure with microstructures formed on the surface of a substrate according to an embodiment of the present invention. Among them, the present invention can also further form at least one microstructure 511 on the contact surface of the first conductive layer 50 covering the upper surface 411, the lower surface 412 of the substrate 40 and the hole wall of the through hole 42, so as to pass through the at least one microstructure 511. A microstructure 511 increases the adhesion when covered by the first conductive layer 50 . In other words, in step S115 of Figure 11 of the present invention, the step of forming the first conductive layer 50 through the electroless plating process may further include: covering the upper surface 411, the lower surface 412, and the through layer of the first conductive layer 50 of the base material 40. The microstructure 511 is formed on the contact surface of the hole wall of the hole 42 so as to increase the adhesion when covered by the first conductive layer 50 through the microstructure 511 . For details, please refer to Figures 6 and 7. Figure 6 discloses a schematic diagram of the prior art without damaging the surface of the substrate 10 to form a microstructure. Figure 7 shows a method of forming a microstructure on the substrate 40 according to an embodiment of the present invention. A schematic diagram of destroying the surface to form a microstructure. It can be clearly seen from Figures 6 and 7 that according to the embodiment of the present invention, the microstructure 511 can be in a zigzag shape, for example, or the microstructure 511 can be designed to have a concave and convex height difference. This can slightly damage the surface of the original substrate 40 and form a non-smooth connection between the microstructure 511 and the plated first conductive layer 50, thereby increasing the surface adhesion during metallization plating.

Therefore, in view of the various embodiments of the present invention listed above, the important core concept of the present invention is to make an improvement on the current thick copper substrate structure. Compared with the prior art, the present invention can , only contains a single material base material, so when the subsequent electroless plating process is performed, since the electroless plating process is directly electroless plating on the single material base material, there is no conductor or layered structure as described in the prior art. The difference can naturally solve the problem of uneven process or selective electroless plating thickness in the prior art.

Furthermore, please refer to Figures 8, 9, and 10, which are other embodiments of through holes disclosed according to the present invention. As shown in these figures, the present invention does not use through holes. The formation shape, or the shape of the aperture is limited to the above. The through holes drawn in Figures 4B to 4D and Figure 5 are only for explaining one of the exemplary examples of the technical solution of the present invention. In other embodiments of the present invention, through holes The holes may also be implemented in a circular hole, a square hole, a diamond hole, an inverted trapezoidal hole, a trapezoidal hole, or a through hole shape with an irregular hole wall structure. For example, it can be a trapezoidal hole 42A as shown in Figure 8, an inverted trapezoidal hole 42B as shown in Figure 9, or an irregular hole 42C as shown in Figure 10. Generally speaking, those with ordinary knowledge in the art can adjust the shape of the through holes according to the actual manufacturing process and needs. However, as long as the invention is equal and does not deviate from the spirit of the invention, it should still fall within the scope of the invention. .

From this point of view, it can be seen that the present invention mainly uses an electroless plating process to simultaneously complete the conductive layers on the upper and lower surfaces of the substrate and the through holes, thereby eliminating the conventional two process steps of sputtering layer and second electroplating layer. , effectively improving the complexity of the existing process and its process cost.

On the other hand, by using the technical solution disclosed in the present invention and using only a single material as a base material, the generation of slag and drilling dirt can be reduced during the subsequent drilling process, thereby maintaining good cleanliness and process quality. Controllable and simple.

In addition, it can be established that through the technical features and technical means disclosed in the present invention, the double-sided conductive laminated structure disclosed in the present invention can be further widely used in transparent display devices, thereby effectively improving the present invention. The applicability of the invention and its compliance with market demand.

Therefore, in view of the above, it is obvious that compared with the conventional technology, the present invention successfully solves the existing problems in the prior art, and is proven to achieve significant and more effective inventive effects. Therefore, the technical solution disclosed in the present invention indeed has excellent industrial applicability and competitiveness. It is obvious that the technical features, methods and effects disclosed in the present invention are significantly different from existing solutions and cannot be easily accomplished by those familiar with the technology. Therefore, patent requirements should be met.

It is worth reminding that based on the technical solutions taught in the present invention, those with ordinary knowledge in the art can change the design on their own at the actual implementation level, which all fall within the scope of the present invention. The purpose of the several illustrative examples listed in the preceding paragraphs of the present invention is to better explain the main technical features of the present invention, so that those in the art can understand and implement them accordingly. However, the present invention should not be based on these examples. Limited to some illustrative examples.

10…Substrate 11…conductive layer 12…metallic copper layer 13…through hole 20…Electroless metal plating layer 22…medium layer 40…Substrate 411…upper surface 412…lower surface 42…through hole 42A…trapezoidal hole 42B…inverted trapezoidal hole 42C…Irregular shaped hole 50…first conductive layer 60…Second conductive layer 100...Double-sided conductive laminated structure 511…Microstructure S111, S113, S115, S117… steps

Figures 1A to 1F are schematic structural diagrams corresponding to each step of the prior art process using thick copper substrates. Figure 2 is a schematic diagram of the structure of a thick copper substrate with a dielectric layer in the prior art. Figure 3 is a schematic structural diagram of the selectivity problem when forming an electroless metal layer based on the structure of Figure 2. 4A to 4D are structural schematic diagrams corresponding to each process step of forming a double-sided conductive laminated structure according to embodiments of the present invention. Figure 5 is a schematic diagram of a double-sided conductive laminated structure with microstructures formed on the surface of a substrate according to an embodiment of the present invention. Figure 6 is a schematic diagram of the prior art without damaging the surface of the substrate to form microstructures. Figure 7 is a schematic diagram of destroying the surface of a substrate to form microstructures according to an embodiment of the present invention. Figure 8 is a schematic diagram of a trapezoidal hole according to an embodiment of the present invention. Figure 9 is a schematic diagram of an inverted trapezoidal hole according to another embodiment of the present invention. Figure 10 is a schematic diagram of an irregular-shaped hole according to yet another embodiment of the present invention. FIG. 11 is a flow chart of a method for manufacturing a double-sided conductive laminated structure according to an embodiment of the present invention.

40…Substrate 411…upper surface 412…lower surface 50…first conductive layer 60…Second conductive layer 100...Double-sided conductive laminated structure

Claims (23)

A double-sided conductive laminated structure includes: a base material having an upper surface and a lower surface relative to the upper surface; at least one through hole is formed between the upper surface and the lower surface of the base material; a first A conductive layer covering the upper surface, the lower surface, and the hole wall of at least one through hole of the base material; and a second conductive layer covering the third conductive layer located on the upper surface of the base material. A conductive layer, the second conductive layer also covers the first conductive layer located on the lower surface of the base material, thereby providing electrical conduction between the upper surface and the lower surface of the base material; wherein, in the first At least one microstructure is formed on the contact surface of the upper surface, the lower surface, and the hole wall of the at least one through hole covered by the conductive layer to increase the coverage of the first conductive layer through the at least one microstructure. of adhesion. The double-sided conductive laminated structure as claimed in claim 1, wherein the first conductive layer is formed through an electroless plating process. The double-sided conductive laminated structure as claimed in claim 1, wherein the second conductive layer is formed through an electroplating process. The double-sided conductive laminated structure as claimed in claim 1, wherein the first conductive layer is made of metal or an alloy thereof. The double-sided conductive laminated structure as claimed in claim 4, wherein the first conductive layer is made of copper. The double-sided conductive laminated structure as claimed in claim 1, wherein the at least one microstructure is in a zigzag shape. The double-sided conductive laminated structure as claimed in claim 1, wherein the at least one microstructure has a height difference between concave and convex. The double-sided conductive laminated structure as claimed in claim 1, wherein the thickness of the first conductive layer is between 0.3 and 3.0 microns. The double-sided conductive laminated structure as claimed in claim 1, wherein the uniformity of the first conductive layer is less than 20%. The double-sided conductive laminated structure as claimed in claim 1, wherein the substrate is made of a transparent or translucent material. The double-sided conductive laminated structure as claimed in claim 1, wherein the thickness of the substrate is greater than 25 microns. The double-sided conductive laminated structure as claimed in claim 1, wherein the transmittance of the substrate is greater than 80%. A method for manufacturing a double-sided conductive laminated structure, including the following steps: providing a base material having an upper surface and a lower surface relative to the upper surface; between the upper surface and the lower surface of the base material At least one through hole is formed between them; a first conductive layer is formed through a chemical plating process, and the first conductive layer covers the upper surface, the lower surface of the substrate, and the hole wall of the at least one through hole; and through An electroplating process forms a second conductive layer that covers the first conductive layer located on the upper surface of the substrate, and the second conductive layer also covers the first conductive layer located on the lower surface of the substrate, Thereby, the upper surface and the lower surface of the base material are electrically connected. The manufacturing method of a double-sided conductive laminated structure as claimed in claim 13, wherein the material of the first conductive layer is metal or an alloy thereof. The manufacturing method of a double-sided conductive laminated structure as claimed in claim 14, wherein the first conductive layer is made of copper. The manufacturing method of a double-sided conductive laminated structure as claimed in claim 13, wherein the step of forming the first conductive layer through the electroless plating process further includes: covering the first conductive layer At least one microstructure is formed on the contact surface of the upper surface, the lower surface, and the hole wall of the at least one through hole of the substrate, so as to increase the adhesion when covering the first conductive layer through the at least one microstructure. The manufacturing method of a double-sided conductive laminated structure as claimed in claim 16, wherein the at least one microstructure is in a zigzag shape. The manufacturing method of a double-sided conductive laminated structure as claimed in claim 16, wherein the at least one microstructure has a height difference between concave and convex. The manufacturing method of a double-sided conductive laminated structure as claimed in claim 13, wherein the thickness of the first conductive layer is between 0.3 and 3.0 microns. The manufacturing method of a double-sided conductive laminated structure as claimed in claim 13, wherein the uniformity of the first conductive layer is less than 20%. The manufacturing method of a double-sided conductive laminated structure as claimed in claim 13, wherein the base material is made of a transparent or translucent material. The method for manufacturing a double-sided conductive laminated structure as claimed in claim 13, wherein the thickness of the substrate is greater than 25 microns. The manufacturing method of a double-sided conductive laminated structure as claimed in claim 13, wherein the transmittance of the substrate is greater than 80%.