Method for manufacturing fine lines by means of plasma gas and circuit board comprising fine lines

Abstract

The application provides a method for manufacturing fine lines by using plasma gas and a circuit board with fine lines. The method comprises the following steps: the surface of a raw substrate is sequentially coated with a first photosensitive dry film, exposed and developed to obtain a first substrate, the non-line area of the first substrate is coated with a film, and the line area of the first substrate is exposed; the inorganic substance in the line area of the first substrate is reacted and gasified in a plasma gas, then vacuum is extracted and an ablation gas is introduced in sequence, the ablation gas reacts with the line area of the first substrate to powderize the line area and form a line groove; the line groove is sequentially cleaned and activated; the process is repeated until a complete line groove is obtained; the first photosensitive dry film is removed to obtain a second substrate; and the second substrate is subjected to subsequent treatment to obtain a circuit board with fine lines. The method has a wide application range and the precision can reach within 0.5 mil.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit board manufacturing, and in particular to a method for manufacturing fine circuit lines by using plasma gas and a circuit board comprising fine circuit lines. BACKGROUND

[0002] With the rapid development of electronic products, circuit boards as supporting bodies of components and carriers for transmitting electrical signals are gradually developing towards miniaturization, light weight, high density and multifunction. Therefore, higher requirements are put forward for the performance of circuit boards, especially the precision of circuit lines, i.e. the line width tolerance is required to be smaller and smaller.

[0003] At present, the methods for manufacturing circuit lines of circuit boards mainly include subtractive method, semi-additive method or additive method. The subtractive method has a processing capacity of more than 5 mil, and the semi-additive method or the additive method pollutes the environment with chemical water and cannot process lines with a width of less than 2 mil. Therefore, it is necessary to research, optimize and improve the manufacturing process of fine circuit lines. SUMMARY

[0004] To solve the above technical problems, the present application provides a method for manufacturing fine circuit lines by using plasma gas and a circuit board comprising fine circuit lines. The method can manufacture circuit boards with a precision of less than 0.5 mil by using plasma organic gas, thereby making up for the manufacturing defects of fine circuit lines in the industry.

[0005] To achieve the above purpose, the present application adopts the following technical solutions:

[0006] In a first aspect, the present application provides a method for manufacturing fine circuit lines by using plasma gas, which comprises the following steps:

[0007] (1) The surface of a raw substrate is sequentially coated with a first photosensitive dry film, exposed and developed to obtain a first substrate. The non-circuit line area of the first substrate is coated with a film, and the circuit line area of the first substrate is exposed;

[0008] (2) The inorganic matter in the circuit line area of the first substrate is gasified by reaction in plasma gas, and then vacuum is extracted and ablation gas is introduced. The ablation gas reacts with the circuit line area of the first substrate to powderize the circuit line area and form a circuit line groove. The circuit line groove is sequentially cleaned and activated;

[0009] (3) Step (2) is repeated until a complete circuit line groove is obtained. The first photosensitive dry film is removed to obtain a second substrate;

[0010] (4) the second substrate obtained in step (3) is subjected to whole-board chemical copper plating, and then the hole positions of the circuit groove are filled with electroplating, and then the surface of the second substrate is subjected to copper reduction treatment or grinding treatment until the substrate of the circuit area is exposed, to obtain a third substrate;

[0011] or the second substrate obtained in step (3) is subjected to whole-board targeted sputtering, which sequentially covers the circuit area and the sidewalls and bottom of the hole positions of the circuit groove with a metal layer, and then a second photosensitive dry film is attached again, the non-circuit area is exposed and cured, the circuit area is developed, the recess of the circuit area is exposed, the bottom and sidewalls of the recess contain a layer of copper, and then the recess is filled with electroplating to fill the recess with copper, the second photosensitive dry film is removed, and the copper of the non-circuit area and the non-via hole positions is removed until the substrate of the non-circuit area is exposed, to obtain a third substrate.

[0012] In the present application, the inorganic matter in the circuit area of the first substrate is subjected to reaction gasification in a plasma gas, wherein the inorganic matter is mainly inorganic fillers such as Si, Al or Mg, which can better control the precision of the circuit board; then an ablation gas is introduced for ablation, which has the advantages of not polluting water and fine circuit can reach 5μm compared with other etching methods. The subsequent scheme of whole-board chemical copper plating and filling the hole positions of the circuit groove with electroplating has the effect of plating the groove to form a circuit, and the overall process strictly controls each step, which can control the precision of the circuit within 0.5mil, and the uniformity of etching is above CPK2.0.

[0013] The two schemes in step (4) are not superior or inferior, the first scheme is suitable for small batch production and has the advantages of fine processing and good flatness. The second scheme is suitable for batch production and has the advantage of high production efficiency.

[0014] Preferably, the first photosensitive dry film in step (1) is a photosensitive film.

[0015] Preferably, the original substrate includes a copper-clad plate or a copper-clad plate without copper.

[0016] Preferably, when the original substrate is a copper-clad plate, step (1) further includes etching and removing the exposed copper surface after development to expose the circuit area of the first substrate.

[0017] Preferably, the plasma gas in step (2) includes a combination of plasma argon, oxygen + oxygen followed by argon, or hydrogen + hydrogen followed by argon.

[0018] The present application preferably uses a plasma gas to react and gasify the inorganic matter in the circuit area. If this step is not performed, the inorganic matter in the substrate cannot be removed, which will cause problems in the subsequent ablation step.

[0019] The oxygen+oxygen and then argon or hydrogen+hydrogen and then argon in the present application means that before the plasma argon etching, the plasma oxygen or plasma hydrogen can be introduced twice, which can clean the surface.

[0020] Preferably, the temperature of the reaction gasification is 50-100℃, for example, it can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 90℃ or 100℃, etc.

[0021] The absolute vacuum degree of the vacuumization is not particularly limited in the present application, and any vacuum degree that can be used for plasma gas reaction gasification known to those skilled in the art can be used, for example, it can be 80-110 Pa, etc.

[0022] Preferably, the ablation gas comprises carbon tetrafluoride gas.

[0023] The flow of the ablation gas is not particularly limited in the present application, and can be determined according to the filler of the original substrate and the depth, width and density of the circuit groove to be etched.

[0024] Preferably, the temperature of the ablation reaction is 180-190℃, for example, it can be 180℃, 181℃, 182℃, 183℃, 184℃, 185℃, 186℃, 187℃, 188℃ or 190℃, etc.

[0025] Preferably, the circuit groove is cooled first and then cleaned.

[0026] Preferably, the metal layer in step (4) comprises a titanium layer and a copper layer in sequence from the second substrate.

[0027] Preferably, the second photosensitive dry film comprises a photosensitive film.

[0028] Preferably, when the circuit board is a multilayer board, the method further comprises, after step (4): pressing at least two third substrates made to form a multilayer board with prepreg.

[0029] Preferably, when the circuit board is an HDI board or an outer layer circuit board, the method further comprises, after step (4): the shiny surface of the copper foil can be used to contact the prepreg and then pressed, and then the copper foil is removed to expose the substrate. Or a smooth plastic material resistant to 220 degrees high temperature, which can be directly removed after pressing.

[0030] The method of the present application can be used to process the inner layer circuit and the outer layer circuit. The object of processing can be a copper-clad plate containing copper, a multilayer circuit board before pressing to make a circuit, and also applicable to a copper-clad plate without copper or a multilayer circuit board without copper after pressing.

[0031] For HDI boards, the remaining processing steps can be the same as those for HDI boards.

[0032] The present invention does not have special requirements for the whole board chemical copper plating, hole filling electroplating, copper reduction treatment or grinding treatment steps. Any feasible steps or processes known to those skilled in the art can be used, and can also be adapted according to the actual situation.

[0033] The detailed grinding process in this invention includes: ceramic grinding --> sandbag grinding --> non-woven fabric grinding, or grinding with a wafer grinding device after fixing. Any grinding equipment commonly recognized in the industry is acceptable, and no special limitation is made.

[0034] The present invention does not impose any special limitation on the thickness of the first and second photosensitive dry films. Any thickness known to those skilled in the art can be used, and adjustments can be made according to actual conditions.

[0035] In a second aspect, the present invention provides a circuit board containing fine lines, wherein the fine lines in the circuit board are fabricated using the method for fabricating fine lines using plasma gas as described in the first aspect.

[0036] The circuit board provided by the second aspect of the present invention contains fine circuitry, thereby improving the accuracy of the circuit board.

[0037] Preferably, the circuit board includes a multilayer circuit board or a single-layer circuit board.

[0038] Compared with the prior art, the present invention has at least the following beneficial effects:

[0039] The method for fabricating fine circuits using plasma gas provided by this invention can achieve a circuit accuracy of 0.5 mil, with a tolerance of 0.5 mil within 10%, and an etching uniformity ≥ CPK2.0. This is beneficial for circuit boards to gradually develop towards miniaturization, lightweighting, high density, and multifunctionality. Detailed Implementation

[0040] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0041] It should be understood that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0042] The specific process and parameters involved in the following specific embodiments are not specifically defined, and the processes and conventional parameters well known to those skilled in the art can be used, and no special limitation is made.

[0043] Example 1

[0044] The present embodiment provides a method for manufacturing fine lines by using plasma gas, which comprises the following steps:

[0045] (1) The surface of the original substrate is sequentially coated with a first photosensitive dry film (photosensitive film), exposed and developed to obtain a first substrate, the non-line area of the first substrate is coated with a film, and the line area of the first substrate is exposed;

[0046] (2) The inorganic matter in the line area of the first substrate is reacted and gasified at 60°C in a plasma gas (plasma argon), then sequentially vacuumed to 100 Pa and introduced into an ablation gas (carbon tetrafluoride gas), the ablation gas is reacted with the line area of the first substrate to powderize the line area and form a line groove; the line groove is sequentially cleaned and activated;

[0047] (3) Step (2) is repeated until a complete line groove is obtained; and the first photosensitive dry film is removed to obtain a second substrate;

[0048] (4) The second substrate obtained in step (3) is sequentially subjected to full-plate chemical copper plating, hole filling electroplating to the hole site of the line groove, and then the surface of the second substrate is subjected to copper reduction treatment until the substrate of the line area is exposed to obtain a third substrate;

[0049] (5) At least two third substrates manufactured are laminated with a prepreg to form a multi-layer board.

[0050] Example 2

[0051] The present embodiment provides a method for manufacturing fine lines by using plasma gas, which comprises the following steps:

[0052] (1) The surface of the original substrate is sequentially coated with a first photosensitive dry film (photosensitive film), exposed and developed to obtain a first substrate, the non-line area of the first substrate is coated with a film, and the line area of the first substrate is exposed;

[0053] (2) The inorganic matter in the line area of the first substrate is reacted and gasified at 80°C in a plasma gas (plasma oxygen + oxygen in argon), then sequentially vacuumed to 80 Pa and introduced into an ablation gas (carbon tetrafluoride gas), the ablation gas is reacted with the line area of the first substrate to powderize the line area and form a line groove; the line groove is sequentially cleaned and activated;

[0054] (3) repeating step (2) until a complete circuit groove is obtained; and removing the first photosensitive dry film to obtain a second substrate;

[0055] (4) the second substrate obtained in step (3) is subjected to whole-board chemical copper plating, and the hole sites of the circuit groove are filled with electroplating, and then the surface of the second substrate is ground until the substrate of the circuit area is exposed to obtain a third substrate;

[0056] (5) the shiny surface of the copper foil is contacted with the prepreg using a laser, and then the copper foil is removed to expose the substrate.

[0057] Example 3

[0058] The embodiment provides a method for manufacturing a fine circuit by using a plasma gas, and the method comprises the following steps:

[0059] (1) the surface of a raw substrate is sequentially subjected to a first photosensitive dry film (photosensitive film film), exposure and development to obtain a first substrate, the non-circuit area of the first substrate is covered with a film, and the circuit area of the first substrate is exposed;

[0060] (2) the inorganic matter in the circuit area of the first substrate is gasified by reacting at 70°C in a plasma gas (plasma argon gas), and then sequentially subjected to vacuum extraction to 90 Pa and introduction of ablation gas (carbon tetrafluoride gas), the ablation gas reacts with the circuit area of the first substrate to powderize the circuit area to form a circuit groove; the circuit groove is sequentially subjected to cleaning and activation treatment;

[0061] (3) repeating step (2) until a complete circuit groove is obtained; and removing the first photosensitive dry film to obtain a second substrate;

[0062] (4) the second substrate obtained in step (3) is subjected to whole-board targeted sputtering, the circuit area and the sidewall and bottom of the hole site of the circuit groove are sequentially covered with a metal layer, and then a second photosensitive dry film (photosensitive film film) is attached again, the non-circuit area is subjected to exposure and curing, the circuit area is developed to expose the recess of the circuit area, the recess contains a layer of copper at the bottom and the sidewall, and then the recess is subjected to hole filling electroplating to fill the recess with copper to a certain thickness, the second photosensitive dry film is removed, and the copper of the non-circuit area and the non- through hole site is removed until the substrate of the non-circuit area is exposed to obtain a third substrate;

[0063] (5) the shiny surface of the copper foil is contacted with the prepreg using a laser, and then the copper foil is removed to expose the substrate.

[0064] Example 4

[0065] The embodiment provides a method for manufacturing fine lines by using plasma gas, and the method comprises the following steps.

[0066] (1) The surface of an original substrate is sequentially attached with a first photosensitive dry film (photosensitive film), exposed, and developed to obtain a first substrate, a non-line area of the first substrate is attached with a film, and a line area of the first substrate is exposed;

[0067] (2) Inorganic substances in the line area of the first substrate are reacted and gasified at 65 DEG C in plasma gas (plasma argon), then vacuumized to 95 Pa and plasma gas (carbon tetrafluoride gas) is introduced, the plasma gas is ablated with the line area of the first substrate to powderize the line area and form a line groove, and the line groove is sequentially cleaned and activated;

[0068] (3) Step (2) is circularly performed until a complete line groove is obtained, and the first photosensitive dry film is removed to obtain a second substrate;

[0069] (4) The second substrate obtained in step (3) is subjected to whole plate target sputtering, the whole plate target sputtering sequentially covers the line area and the sidewall and bottom of the hole site of the line groove with a metal layer, then a second photosensitive dry film (photosensitive film) is attached again, the non-line area is exposed and solidified, the line area is developed to expose the groove of the line area, the bottom and sidewall of the groove contain a layer of copper, the groove is sequentially filled with a hole electroplating to fill the groove with copper, the second photosensitive dry film is removed, and the copper of the non-line area and the non-via hole site is removed until the substrate of the non-line area is exposed to obtain a third substrate;

[0070] (5) The light surface of a copper foil is contacted with a prepreg by using a laser, and then pressed and combined, then the copper foil is removed from the substrate, and the remaining processing procedure is consistent with the processing procedure of HDI.

[0071] Example 5

[0072] The embodiment provides a method for manufacturing fine lines by using plasma gas, and the method is same as that in example 1 except that the temperature of ablation reaction is 45 DEG C.

[0073] In the embodiment, the temperature of ablation reaction is relatively low, so that the line groove is shallowly ablated, it is difficult to form continuous lines, and the line board is not successfully manufactured.

[0074] Comparative Example 1

[0075] The comparative example provides a method for manufacturing fine lines by using plasma gas, and the method is same as that in example 1 except that the inorganic substances in the line area of the first substrate are not reacted and gasified in the plasma gas in step (2).

[0076] The comparative example cannot be matched with the carbon tetrafluoride gas to play an ablation effect, and cannot make a circuit board because the plasma gas is not used for reaction gasification in the front.

[0077] Comparative Example 2

[0078] The comparative example provides a method for making a circuit by chemical etching, which adopts the method of Example 3 in CN112702846A.

[0079] The above-mentioned examples and comparative examples are used to make 0.5 mil, 2 mil and 3 mil circuits, and the maximum tolerance and etching uniformity of the circuits made are calculated.

[0080] The test results of the above examples and comparative examples are shown in Table 1.

[0081] Table 1

[0082]

[0083] In Table 1, " / " indicates that the relevant product cannot be made or the yield is low.

[0084] From Table 1, it can be seen that the method provided by the present application can make a fine circuit of 0.5 mil, and the tolerance is within 10.2%, and the etching uniformity is ≥CPK2.0; compared with chemical etching, the etching uniformity of the method provided by the present application is higher, and the tolerance of 3 mil reaches more than 15%, and the method provided by the present application can make a circuit of 0.5 mil.

[0085] The applicant declares that the above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for fabricating fine circuits using plasma gas, characterized in that, The method includes the following steps: (1) The surface of the original substrate is sequentially coated with a first photosensitive dry film, exposed and developed to obtain a first substrate. The non-circuit area of ​​the first substrate is covered by the film, and the circuit area of ​​the first substrate is exposed. (2) The inorganic material in the circuit area of ​​the first substrate is vaporized by reaction in plasma gas, and then vacuumed and ablation gas is introduced in sequence. The ablation gas reacts with the circuit area in the first substrate to pulverize the circuit area and form a circuit groove. The circuit groove is then cleaned and activated in sequence. The plasma gas includes plasma argon, oxygen + oxygen followed by argon, or hydrogen + hydrogen followed by argon. The reaction vaporization temperature is 50~100℃. The ablation gas is carbon tetrafluoride gas. (3) Repeat step (2) until a complete circuit groove is obtained; and remove the first photosensitive dry film to obtain the second substrate; (4) The second substrate obtained in step (3) is subjected to whole-board chemical copper plating, and the holes of the circuit groove are filled by electroplating. Then, the surface of the second substrate is subjected to copper reduction treatment or grinding treatment until the substrate of the circuit area is exposed to obtain the third substrate. Alternatively, the second substrate obtained in step (3) is subjected to whole-board targeted sputtering, in which the whole-board targeted sputtering sequentially covers the sidewalls and bottom of the circuit area and the hole position of the circuit groove with a metal layer, and then the second photosensitive dry film is applied again, and the non-circuit area is exposed and cured. The circuit area is developed to expose the groove of the circuit area. The bottom and sidewall of the groove contain a layer of copper. Then the groove is sequentially filled with copper by electroplating to fill the groove with copper thickness. The second photosensitive dry film is removed, and the copper of the non-circuit area and the non-conductive hole position is removed until the substrate of the non-circuit area is exposed to obtain the third substrate. The tolerance of the 0.5 mil fine lines prepared by the method is ≤10.2%; the etching uniformity is ≥CPK2.

0.

2. The method according to claim 1, characterized in that, In step (1), the first photosensitive dry film is a photosensitive film.

3. The method according to claim 1, characterized in that, The original substrate mentioned in step (1) includes copper-clad laminate containing copper or copper-free copper-clad laminate.

4. The method according to claim 1, characterized in that, When the original substrate is a copper-clad laminate containing copper, the development process in step (1) further includes: etching away the exposed copper surface to expose the circuit area of ​​the first substrate.

5. The method according to claim 1, characterized in that, The circuit trough is cooled before being cleaned.

6. The method according to claim 1, characterized in that, The metal layer in step (4) includes a titanium layer and a copper layer sequentially from the second substrate.

7. The method according to claim 1, characterized in that, The second photosensitive dry film includes a photosensitive film.

8. The method according to claim 1, characterized in that, When the circuit board is a multilayer board, the method further includes, after step (4): pressing at least two completed third substrates and prepregs together to form a multilayer board.

9. The method according to claim 8, characterized in that, When the circuit board is an HDI board or an outer circuit board, the method further includes, after step (4): using the smooth surface of copper foil to contact the prepreg and press it together, and then removing the copper foil to expose the substrate; or a smooth plastic material resistant to 220 degrees Celsius, which can be directly peeled off and reused after pressing.

10. A circuit board containing fine lines, characterized in that, The fine lines in the circuit board containing fine lines are prepared by the method of preparing fine lines using plasma gas as described in any one of claims 1 to 9.

11. The circuit board containing fine lines according to claim 10, characterized in that, The circuit board may be a multilayer circuit board or a single-layer circuit board.

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