TWI808706B - Manufacturing method of circuit board structure and circuit board structure manufactured thereof - Google Patents

Abstract

A manufacturing method of circuit board structure comprises: providing a substrate which comprising a substrate layer and two copper layers, wherein two copper layers are formed on opposite sides of the substrate layer; forming two metallic conductor layers separately covering the two copper layers by electroplating; drilling the metallic conductor layer on a first surface side to form holes until the copper layer on a second surface side of the substrate layer exposed; forming a metallization layer by chemical means, wherein the metallization layer covers the surface of the hole and the surface of the two metallic conductor layers; forming a copper-clad layer by electroplating, wherein the copper-clad layer covers the holes, the metallic conductor layer on the first surface side and the second surface side; removing part of the copper-clad layer that exceeds over the copper layer by chemical etching; and removing the two metallic conductor layers by chemical etching.

Description

Manufacturing method of circuit board structure and manufactured circuit board structure

A method for manufacturing a circuit board structure, and the manufactured circuit board structure.

The common selective electroplating method for circuit boards mostly uses photoresist material for the masking layer material. Because the masking layer is made of photoresist material, the photoresist property is usually either acid resistance or alkali resistance, and it cannot be resistant to acid or alkali at the same time. In the mainstream metallization system, there are both acidic and alkaline solutions. Therefore, the metallization must be done before the photoresist material can be covered in the process. The process is to carry out metallization after drilling and clearing the holes, and then use photoresist masking, exposure and development to expose the metallized holes, and then electroplating. Because the drilling process and the exposure process have process tolerance problems, the photoresist hole opening process must be opened according to the position of the drilled hole, and equipment with automatic alignment (CCD exposure machine or digital direct drawing exposure machine) must be used. Due to the problem of progressive tolerance, the opening size must be enlarged. A protrusion is formed around the hole. In circuit fabrication, in order to effectively cover the protrusions, the thickness of the photoresist cannot be thinned, resulting in limitations in resolution and etching molding, which affects the fabrication of thin circuits in the circuit structure of the circuit board.

Although there is a new metallization system, the overall metallization process is a neutral or weakly acidic system, which is relatively compatible with the operating conditions of the photoresist, and the metallization method with the photoresist will make the surface of the photoresist conductive. In addition, the photoresist will also be plated, so in order to remove the photoresist smoothly, it is necessary to remove the plating material on the photoresist. Because the photoresist itself is non-conductive, the photoresist is conductive after metallization, but after all, the non-metallic material is not as uniform as metal, and it is easy to cause uneven copper plating on the photoresist. The use of neutral or weakly acidic metallization systems is limited in applicability.

In view of this, the present case provides a manufacturing method of a circuit board structure in one embodiment, including providing a substrate, the substrate includes a base material layer and two copper layers, each copper layer is formed on the first surface and the second surface opposite to the base material layer; two metal-clad conductor layers are formed by electroplating, and the two metal-clad conductor layers cover the surfaces of the two copper layers respectively. Drilling holes from the surface of the metal-clad conductor layer on the first surface side to form holes, the holes are connected to expose the copper layer on the second surface of the base layer; forming a metallization layer by chemical means, the metallization layer covers the surface of the hole and the surface of the second metal-clad conductor layer; forming a copper-clad layer by electroplating, the copper-clad layer covers the surface of the hole and extends to the surface of the metal-clad conductor layer on the first surface side, and covers the surface of the metal-clad conductor layer on one side of the second surface. The portion of the copper clad layer that exceeds the height of the copper layer is removed by chemical etching. The overlying metallic conductor layer is removed by chemical etching.

In some embodiments, the metal-clad conductor layer is chromium, nickel, aluminum, titanium, tin, platinum, gold or silver.

In some embodiments, two copper layers are connected through the copper clad layer through at least one hole.

In some embodiments, during the drilling process, at least one hole is connected to the metal-clad conductor layer on one side of the second surface.

In some embodiments, during the process of removing part of the copper clad layer exceeding the height of the copper layer by chemical etching, the height of the copper clad layer and the copper layer are substantially aligned by chemical etching.

In some embodiments, at least one hole is formed by laser drilling, mechanical drilling or punching.

In some embodiments, the material of the second metal-clad conductor layer is a metal material resistant to acid and alkali, and the thickness is 0.1 to 20 μm.

In some embodiments, after removing the two metal-clad conductor layers through chemical etching; covering the two photoresist layers on the surface of the two copper layers, and through exposure and development, the two photoresist layers form a circuit pattern structure; performing an etching process to remove the surface of each copper layer not covered by each photoresist layer; and removing the two photoresist layers.

In addition, according to an embodiment, a circuit board structure is provided, which is a circuit board structure manufactured by the manufacturing methods of the above-mentioned embodiments.

To sum up, by plating the metal conductor layer on the substrate, since the material is an acid and alkali resistant metal conductor, and the metal conductor layer is not limited to neutral or weak acid metallization systems, the current mainstream metallization system can also be used, which improves the efficiency of circuit board structure manufacturing and increases the diversity of manufacturing methods. The metal-clad conductor layer is covered by chemical deposition or electroplating on the two copper layers. The characteristics of changing from traditional pattern plating to full plate plating make the overall plating uniformity easier to control than pattern plating. When removing the plating layer on the metal conductor layer later, it will not be difficult to remove due to excessive thickness differences.

100: Circuit board structure

10: Substrate

11: Substrate layer

111: first surface

112: second surface

12a, 12b: copper layer

13a, 13b: metal clad conductor layer

14: Metallization layer

15: Copper clad layer

16: Photoresist layer

161: Line pattern structure

20: hole

21: hole wall

22: Hole bottom

30: hole

31: hole wall

S10-S19: Steps

[FIG. 1] is a structural schematic diagram (1) of a method for fabricating a circuit board structure according to a first embodiment.

[ Fig. 2 ] is a structural schematic diagram (2) of a method for manufacturing a circuit board structure according to a first embodiment.

[ FIG. 3 ] is a structural schematic diagram (3) of a method for fabricating a circuit board structure according to a first embodiment.

[ FIG. 4 ] is a structural schematic view (four) of a method for fabricating a circuit board structure according to a first embodiment.

[ FIG. 5 ] is a structural schematic diagram (5) of a method for fabricating a circuit board structure according to a first embodiment.

[FIG. 6a] is a structural schematic diagram (6) of a method for fabricating a circuit board structure according to a first embodiment.

[ FIG. 6 b ] is a schematic diagram (1) of the structure of the copper clad layer according to another form of the circuit board structure manufacturing method of the first embodiment.

[ FIG. 7 ] is a structural schematic diagram (7) of a method for fabricating a circuit board structure according to a first embodiment.

[FIG. 7a] is a structural schematic view (eight) of a method for fabricating a circuit board structure according to a first embodiment.

[FIG. 7b] is a structural schematic diagram (9) of a method for fabricating a circuit board structure according to a first embodiment.

[FIG. 7c] is a schematic diagram (2) of the structure of the copper clad layer according to another form of the circuit board structure manufacturing method of the first embodiment.

[ FIG. 8 ] is a structural schematic view (1) of a method for fabricating a circuit board structure according to a second embodiment.

[ Fig. 9 ] is a structural schematic diagram (2) of a method for manufacturing a circuit board structure according to a second embodiment.

[ Fig. 10 ] is a structural schematic diagram (3) of a circuit board structure manufacturing method according to a second embodiment.

[ FIG. 11 ] is a flow chart (1) of a method for manufacturing a circuit board structure according to a first embodiment.

[ FIG. 12 ] is a flow chart (2) of a circuit board structure manufacturing method according to a first embodiment.

Please refer to Fig. 1 to Fig. 6a, Fig. 7 and Fig. 11 first, Fig. 1 to Fig. 6a are the schematic structural diagrams (1) to (6) of the circuit board structure manufacturing method according to a first embodiment, Fig. 7 is the structural schematic diagram (7) of the circuit board structure manufacturing method according to a first embodiment, Fig. 11 is the flow chart (1) of the circuit board structure manufacturing method according to a first embodiment. As shown in FIG. 1 and FIG. 11 , the manufacturing method of the circuit board structure 100 of this embodiment includes providing a substrate 10 (step S10 ), and the substrate 10 includes a base material layer 11 and two copper layers 12a, 12b. The substrate layer 11 has a first surface 111 and a second surface 112 opposite to each other, and two copper layers 12a and 12b are respectively formed on the first surface 111 and the second surface 112 of the substrate layer 11 . For the convenience of subsequent description, the copper layer on the side of the first surface 111 is shown as a copper layer 12a, and the copper layer on the side of the second surface 112 is shown as a copper layer 12b. That is to say, the first surface 111 and the second surface 112 of the substrate layer 11 can be used to fabricate the circuit board structure 100 with the same or different specifications at the same time, or only a single side surface can be used to fabricate the circuit board structure 100 . In the first embodiment, the circuit board structure 100 is fabricated on a single side surface as an example, but not limited thereto.

As shown in Figure 2 and Figure 11, a double-clad metal conductor is formed by electroless plating, sputtering or electroplating. The bulk layers 13a, 13b and the two metal-clad conductor layers 13a, 13b respectively cover the surfaces of the two copper layers 12a, 12b (step S11). For the convenience of subsequent description, the metal-clad conductor layer on the side of the first surface 111 is represented by the metal-clad conductor layer 13a, and the metal-clad conductor layer on the side of the second surface 112 is represented by the metal-clad conductor layer 13b. In the first embodiment, the material of each metal-clad conductor layer 13a, 13b is a metal material that can withstand acid and alkali, and the thickness is 0.1 to 20 μm. Since the thickness of each metal-clad conductor layer 13a, 13b is relatively thin, it can be stripped more efficiently and conveniently in the subsequent stripping operation. In the first embodiment, the acid and alkali resistant metal material is nickel, but not limited thereto, and may also be chromium, aluminum, titanium, tin, platinum, gold or silver.

As shown in FIG. 3 and FIG. 11 , the surface of the metal-clad conductor layer 13a located on one side of the first surface 111 is drilled (step S12) to form a hole 20, and the hole 20 is connected to expose the copper layer 12b located on the second surface 112 of the base material layer 11. In the first embodiment, the holes 20 are formed by laser drilling, but not limited thereto, and the holes 20 may also be formed by mechanical drilling or punching. Here, two holes 20 are used as an example, but not limited thereto. The hole 20 passes through the metal-clad conductor layer 13a, the copper layer 12a and the substrate layer 11 sequentially from the metal-clad conductor layer 13a on one side of the first surface 111 to the copper layer 12b on one side of the second surface 112 to form a hole 20 . The hole 20 includes a hole wall 21 and a hole bottom 22 , and the hole wall 21 includes the side surfaces of the metal-clad conductor layer 13 a , the copper layer 12 a and the substrate layer 11 that are drilled and exposed. The hole bottom 22 includes a surface of the copper layer 12 b bonded to the second surface 112 .

As shown in FIG. 4 and FIG. 11 , the metallization layer 14 is chemically formed (step S13 ), and the metallization layer 14 covers the surface of the hole 20 and the surfaces of the two metal-clad conductor layers 13 a and 13 b. In the first embodiment, the metal-clad conductor layers 13a, 13b are not limited to neutral or weakly acidic metallization systems, and alkaline metallization systems can also be selected. In addition, the metal-clad conductor layer can evenly absorb the metallization layer 14 during the metallization process. In the first embodiment, through weak alkaline, neutral or weak An acidic metallization system is formed and covers the surface of the hole 20 and the surfaces of the two metal-clad conductor layers 13a, 13b. That is to say, the metallization layer 14 covers the surface of the metal-clad conductor layer 13 a on one side of the first surface 111 and the surface of the metal-clad conductor layer 13 b on one side of the second surface 112 . In addition, the coverage of the metallization layer 14 does not include parts of the copper material, such as the side surface of the copper layer 12a exposed by the drill holes and the surface of the copper layer 12b exposed by the drill holes.

As shown in FIGS. 5 and 11 , after the metallization layer 14 is formed, a copper-clad layer 15 is formed by electroplating (step S14). The copper-clad layer 15 covers the surface of the hole 20 and extends to the surface of the metal-clad conductor layer 13a on one side of the first surface 111, and the surface of the metal-clad conductor layer 13b on one side of the second surface 112. In the first embodiment, the surface of the hole 20 is formed and covered by electroplating, that is, the side surfaces of the metal-clad conductor layer 13a, the copper layer 12a and the base material layer 11 exposed due to drilling. In the first embodiment, the copper layer 12 a on the first surface 111 side and the copper layer 12 b on the second surface 112 side are connected through the copper clad layer 15 formed in the hole 20 .

As shown in Figures 6a, 6b and 11, after the electroplating is completed, the copper clad layer 15 that exceeds the height of the copper layer 12a on one side of the first surface 111 and the copper clad layer 15 on one side of the second surface 112 are removed by chemical etching (step S15). In the first embodiment, the copper clad layer 15 removed by bite etching can be removed as shown in FIG. 6a. In order to facilitate subsequent circuit fabrication, the copper clad layer 15 exceeding the height of the copper layer 12a on one side of the first surface 111 and the copper clad layer 15 on one side of the second surface 112 are removed, and the height of the copper clad layer 15 on one side of the first surface 111 is roughly aligned with the height of the copper layer 12a. In addition, the heights of the copper clad layer 15 and the copper layer 12a may have a slight tolerance, for example, the height of the copper clad layer 15 is slightly higher than that of the copper layer 12a or slightly lower than that of the copper layer 12a. Alternatively, the copper clad layer 15 removed by etching may be as shown in FIG. 6 b , which is a schematic diagram (1) of the structure of the copper clad layer according to another aspect of the circuit board structure manufacturing method of the first embodiment. As shown in Figure 6b, in another implementation Among them, for subsequent circuit fabrication, the part of the copper clad layer 15 exceeding the height of the copper layer 12a on one side of the first surface 111 is removed by chemical etching until it is aligned with the metal clad conductor layer 13a. This method is applicable when the thickness of the metal-clad conductor layer 13a is relatively thin (for example, 5 μm or less), at this time, only the copper-clad layer 15 extending to the surface of the metal-clad conductor layer 13a located on one side of the first surface 111 can be removed to form the copper-clad layer 15 slightly higher than the copper layer 12a as shown in FIG. 6b. After the metal-clad conductor layer 13a is removed, although the copper-clad layer 15 slightly protrudes from the copper layer 12a, it will not affect the subsequent circuit process because of its thin thickness.

Continuing with the steps in FIG. 6a, as shown in FIG. 7 and FIG. 12, after the chemical etching is completed, the two metal-clad conductor layers 13a, 13b are removed (step S16), and the circuit board structure 100 is completed.

Specifically, the range of metallization and electroplating is increased by the two metal-clad conductor layers 13a, 13b. During the electroplating process, the copper-clad layer 15 extends to the surface of the metal-clad conductor layer 13a, and then the copper-clad layer 15 exceeding the height range of the metal-clad conductor layer 13a and the two metal-clad conductor layers 13a, 13b are removed together, so that the height of the copper-clad layer 15 is approximately the same as that of the copper layer 12a, and the electroplating layer overflows the hole 20 during the electroplating process. Protrusions are formed around the hole 20 , which affects the fabrication of the circuit board structure 100 . In addition, since the metal-clad conductor layers 13a and 13b are conductive, the metallization layer 14 can be evenly adsorbed during the metallization process, which solves the problem that it is difficult to evenly adsorb the metallization layer 14 when using photoresist in the traditional manufacturing process. In addition, since the photoresist has no anti-alkali effect, it can only be metallized through a neutral or weakly acidic metallization system, while the metal-clad conductor layers 13a, 13b are not limited to neutral or weakly acidic metallization systems, and can also use alkaline metallization systems, which improves the production efficiency of the circuit board structure 100 and increases the diversity of production methods. The metal-clad conductor layers 13a, 13b are covered on the two copper layers 12a, 12b through chemical deposition or electroplating, and the thickness is different. It will be limited by the thickness of the photoresist itself. Since the material of the metal-clad conductor layers 13a and 13b is conductive, the behavior during the electroplating process will change from the traditional pattern plating to the characteristics of the whole board plating, making the overall plating uniformity easier to control than pattern plating. When removing the electroplating layers on the metal-clad conductor layers 13a and 13b later, it will not be difficult to remove due to excessive thickness differences.

In the first embodiment, through the completed circuit board structure, the patterns of subsequent circuits can be continued to be produced. Fig. 7a is a structural schematic diagram (8) of a method for fabricating a circuit board structure according to a first embodiment. Fig. 7b is a structural schematic diagram (9) of a method for fabricating a circuit board structure according to a first embodiment. FIG. 12 is a flow chart (2) of a method for fabricating a circuit board structure according to a first embodiment. 7a, 7b and 12, cover the two photoresist layers 16 on the surface of the two copper layers 12a, 12b, and through exposure and development, the two photoresist layers 16 form a circuit pattern structure 161 (step S17). An etching process is performed to remove the surfaces of the copper layers 12a, 12b not covered by the photoresist layers 16 (step S18). Then the second photoresist layer 16 is removed (step S19 ), and the circuit pattern of the circuit board structure 100 is completed. In the first embodiment, the photoresist layer 16 can be, for example, a dry film photoresist or a wet film photoresist.

Further, please refer to Fig. 7c. Fig. 7c is a schematic diagram (2) of the structure of the copper clad layer of the manufacturing method of the circuit board structure according to another aspect of the first embodiment. Continuing the description of FIG. 6b, the copper clad layer 15 that exceeds the height of the copper layer 12a on one side of the first surface 111 is removed through chemical etching until it is aligned with the metal clad conductor layer 13a, and the two metal clad conductor layers 13a, 13b are removed. The completed circuit board structure 100 will be formed in the form of the copper clad layer 15 slightly higher than the copper layer 12a as shown in FIG. 7c when making circuit patterns later.

Next, please refer to FIG. 8 , FIG. 9 and FIG. 10 . FIG. 8 is a structural schematic view (1) of a method for fabricating a circuit board structure according to a second embodiment. FIG. 9 is a structural schematic diagram (2) of a method for fabricating a circuit board structure according to a second embodiment. Figure 10 is a circuit according to a second embodiment Schematic diagram of the fabrication method of the plate structure (3). In the second embodiment, at least one hole 30 penetrates through the substrate 10 to form a through hole. Parts that are the same as those in the first embodiment will not be repeated, and only some differences will be described. As shown in FIG. 8, holes 30 are formed by mechanical drilling, punching or laser drilling. The holes 30 pass through the metal-clad conductor layer 13a, the copper layer 12a, the substrate layer 11, the copper layer 12b, and the metal-clad conductor layer 13b from the metal-clad conductor layer 13a on one side of the first surface 111 to the metal-clad conductor layer 13b on one side of the second surface 112. The hole 30 includes a hole wall 31 , and the hole wall 31 includes the side surfaces of the metal-clad conductor layer 13 a , the copper layer 12 a , the substrate layer 11 , the copper layer 12 b , and the metal-clad conductor layer 13 b exposed through drilling. The metallization layer 14 covers the surface of the hole 30 , the surface of the metal-clad conductor layer 13 a on one side of the first surface 111 and the surface of the metal-clad conductor layer 13 b on one side of the second surface 112 . Generally, the coverage of the metallization layer 14 does not include parts of the copper material, such as the side surface of the copper layer 12a exposed by the drill holes and the side surface of the copper layer 12b exposed by the drill holes. As shown in FIG. 9 , during the electroplating stage, the copper-clad layer 15 covers the surface of the hole 30 and extends to the surface of the metal-clad conductor layer 13 a on one side of the first surface 111 and the surface of the metal-clad conductor layer 13 b on one side of the second surface 112 . As shown in Figure 10, the copper clad layer 15 partially exceeding the height of the copper layer 12a on one side of the first surface 111 and the copper clad layer 15 partially exceeding the height of the copper layer 12b located on one side of the second surface 112 are removed by chemical etching. After removing the metal-clad conductor layers 13a, 13b, the substrate 10 with the holes 30 (through-holes) filled with the copper-clad layer 15 as shown in FIG. 10 is completed.

In summary, according to an embodiment of a method for fabricating a circuit board structure 100, the two metal-clad conductor layers 13a and 13b are used to increase the range of metallization and electroplating. During the electroplating process, the copper-clad layer 15 extends to the surface of the metal-clad conductor layer 13a, and then the copper-clad layer 15 exceeding the height range of the metal-clad conductor layer 13a and the two metal-clad conductor layers 13a and 13b are removed together, so that the height of the copper-clad layer 15 is approximately the same as that of the copper layer 12a. When plating a hole, the plating overflows the hole A hole is formed around the hole, which affects the fabrication of the circuit board structure 100 . In addition, since the metal-clad conductor layers 13a and 13b are conductive, they can meet the electrical requirements during electroplating without relying on the adsorption effect of the metallization system, and the metal-clad conductor layers 13a and 13b are not limited to neutral or weakly acidic metallization systems, and can also use alkaline metallization systems, which improves the production efficiency of the circuit board structure 100 and increases the diversity of production methods. The metal-clad conductor layers 13a, 13b are covered on the two copper layers 12a, 12b through chemical deposition, sputtering or electroplating. The thickness is not limited by the thickness of the photoresist itself. Because the material of the metal-clad conductor layers 13a, 13b is conductive, the behavior during the electroplating process will change from the traditional pattern plating to the characteristics of the whole board plating, so that the overall plating uniformity is easier to control than the pattern plating. When layering, it will not be difficult to remove due to excessive thickness differences.

S10-S16: Steps

Claims (9)

A method for manufacturing a circuit board structure, comprising: A substrate is provided, the substrate includes a base material layer and two copper layers, the base material layer has a first surface and a second surface opposite, each of the copper layers is formed on the first surface and the second surface of the base material layer; Forming two metal-clad conductor layers through electroless plating, sputtering or electroplating, and the two metal-clad conductor layers respectively cover the surfaces of the two copper layers; Drilling from the surface of the metal-clad conductor layer on one side of the first surface to form at least one hole, the at least one hole is connected to the copper layer exposed on the second surface of the base layer; chemically forming a metallization layer covering the surface of the at least one hole and the surfaces of the two metal-clad conductor layers; forming a copper-clad layer by electroplating, the copper-clad layer covers the surface of the at least one hole and extends to the surface of the metal-clad conductor layer on one side of the first surface, and covers the surface of the metal-clad conductor layer on one side of the second surface; removing portions of the copper clad layer exceeding the height of the copper layer by chemical etching; and The overlying metal conductor layer is removed by chemical etching. The manufacturing method of the circuit board structure according to claim 1, wherein each metal-clad conductor layer is chromium, nickel, aluminum, titanium, tin, platinum, gold or silver. The manufacturing method of the circuit board structure according to claim 1, wherein the copper clad layer through the at least one hole is connected to the two copper layers. The manufacturing method of the circuit board structure as claimed in claim 1, wherein, during the drilling process, the at least one hole is connected to the metal-clad conductor layer on one side of the second surface. The manufacturing method of the circuit board structure as claimed in claim 1, wherein, during the process of removing part of the copper clad layer exceeding the height of the copper layer by chemical etching, the height of the copper clad layer and the copper layer are roughly aligned by chemical etching. The method for manufacturing a circuit board structure as claimed in claim 1, wherein the at least one hole is formed by laser drilling, mechanical drilling or punching. The manufacturing method of the circuit board structure according to claim 1, wherein the thickness of the two metal-clad conductor layers is 0.1 to 20 μm. The manufacturing method of the circuit board structure as described in Claim 1, after removing the two metal-clad conductor layers through chemical etching; Covering two photoresist layers on the surface of the two copper layers, and forming a circuit pattern structure on the two photoresist layers through exposure and development; performing an etching process to remove the surface of each of the copper layers not covered by each of the photoresist layers; and removing the two photoresist layers. A circuit board structure manufactured by the method for manufacturing the circuit board structure described in any one of Claims 1 to 8.

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