CN113046746B

CN113046746B - Precise etching control method for COF (chip on film) winding

Info

Publication number: CN113046746B
Application number: CN202110267848.0A
Authority: CN
Inventors: 郑先锋; 桂珍珍
Original assignee: Hefei Qicai Technology Co ltd
Current assignee: Hefei Qicai Technology Co ltd
Priority date: 2021-03-12
Filing date: 2021-03-12
Publication date: 2023-03-10
Anticipated expiration: 2041-03-12
Also published as: CN113046746A

Abstract

The invention discloses a COF tape precise etching control method, which is characterized in that the addition amount of a strong oxidant is controlled through the potential analysis of an etching solution, and whether the strong oxidant exists in the etching solution is judged by monitoring the potential of the etching solution. The invention solves the defects of the etching line, such as the formation of an inverted ladder and the fuzzy line, in the etching process.

Description

COF (chip on film) tape precise etching control method

Technical Field

The invention relates to the field of COF Film production, in particular to a COF tape accurate etching control method and a COF tape accurate etching control system.

Background

The flexible Film (flexblefilm) is subjected to exposure, development, etching and other stages of engineering transfer to form a predetermined circuit pattern, such as COF (Chip On Film) and Chip On Film (COF). Due to the flexible nature of the film, the film is typically rolled out from one side wheel and then rolled to another side wheel in a Roll-to-Roll manner.

In the COF Film production process, in order to form a fine wiring on a metal, it is necessary to microetch the COF Film with an etching solution, and the microetching is a process of removing copper and a copper alloy by selectively leaving only a circuit in the circuit formation of the COF Film.

In the etching system of high-valence Cu ions + acid + additive, the high-valence Cu ions have oxidizing property and can oxidize Cu into Cu ⁺ The etching reaction is as follows:

high valence Cu ion + Cu → low valence Cu ion

As the etching process proceeds, cu is by-produced ⁺ The etching capability is reduced along with the increase of the etching amount, and the fine control of etching needs to be realized in COF etching, so that the fine control of etching can be realized only by stabilizing each component of the etching solution within a certain range (otherwise, the product does not meet the production requirement), the concentration gradually deviates from the effective range along with the proceeding of the production reaction, and after deviating from the target range, the original etching solution does not meet the etching requirement.

One of the existing methods is to remove the old etching solution as a whole after the etching solution deviates from the target range, add new etching solution for production again, and perform subsequent waste liquid treatment on the removed liquid medicine. And the liquid medicine configuration again consumes a large amount of liquid medicines, and the post-treatment of the discharged liquid medicine also wastes a large amount of resources.

In order to maintain the etching capability, another conventional method is shown in fig. 1, an acid addition port 2, a strong oxidant addition port 3, and an additive addition port 4 are provided on an etching bath 1, before production, an etching solution is prepared in the etching bath 1, during production, after the etching solution deviates from a target range (concentration is analyzed by chemical analysis methods such as high performance chromatography, titrimetric analysis, and the like), an acid solution, a strong oxidant, and an additive are directly and quantitatively supplemented in the etching solution, the etching solution is regenerated, so that low-valent Cu ions are converted into high-valent Cu ions again, the etching solution recovers the normal etching capability, the etching solution is regenerated by adding a strong oxidant such as hydrogen peroxide, and the reaction is:

low valence Cu ion + acid + strong oxidant → high valence Cu ion + H ₂ O

However, this addition method often causes the etched lines to form an inverted ladder as shown in fig. 2 in production (in fig. 2, the bottom 11 of the Cu line is connected to the base of Cof, and the top width H1 and the bottom width H2 are connected), thereby causing product defects such as high short-circuit defect rate and non-straight lines, and even if the frequency of analysis and replenishment is increased, the problem cannot be solved.

Disclosure of Invention

Aiming at the defects, the invention provides a COF tape precise etching control method, which solves the defects of reverse gradient formation and non-straight line of an etched line in the etching process by adding a potential analysis method in the control.

The inventors of the present invention have found, through long-term research, that the above-mentioned defects are caused by the fact that when the volume fraction of the strong oxidizer exceeds a certain value during regeneration of the etching solution, the concentration of the additive is reduced, so that the additive cannot react with the generated Cu + to form a protective film, the etching rate is ensured to be uniform, and the line etching is inverted trapezoidal, thereby causing a short circuit. However, the concentration of the strong oxidant such as H2O2 in the etching solution is low, and it is impossible to analyze whether the strong oxidant exists in the etching solution by chemical methods such as HPLC high performance chromatography, titrimetry, and the like.

The inventor of the invention further researches and discovers that the potential of the etching solution is at a low level under the condition of no hydrogen peroxide, and the potential of the etching solution is at a high level under the condition of hydrogen peroxide.

The invention provides a method for accurately etching and controlling a COF (chip on film) winding, which controls the addition amount of a strong oxidant through potential analysis of an etching solution. The method judges whether the strong oxidant exists in the etching solution or not by monitoring the potential of the etching solution, thereby controlling the concentration of Cu + in the etching solution, ensuring the etching effect of the etching solution, ensuring the stability of the liquid medicine and improving the yield of products.

When the potential of the etching solution is at a high level (strong oxidant exists in the etching solution), by chemically analyzing the concentration of the additive at regular intervals, when the absolute difference value of the two adjacent analysis results is out of a target range (such as 2%), adding copper powder until the potential is at a low level.

The inventors further study and found that when the strong oxidant is excessive and the additive and the acid are added to the etching solution at the same time, a part of the additive reacts with the excessive strong oxidant to affect the use effect of the additive.

Further, in the invention, the method for accurately etching and controlling the COF tape further comprises the steps of independently adding a strong oxidant into the etching solution of the etching bath, forming the etching solution by acid and the additive according to a ratio, and then adding the etching solution into the etching bath.

The invention also provides a COF tape accurate etching control system which comprises an etching upper unit, an etching lower unit, an additive stock solution unit, an acid stock solution unit and a strong oxidant stock solution unit, wherein the etching upper unit is connected with the etching lower unit through a pipeline, the additive stock solution unit, the acid stock solution unit and the strong oxidant stock solution unit are respectively connected with the etching lower unit, the COF tape accurate etching control system is also respectively provided with a chemical analyzer and a potential measuring instrument, the chemical analyzer analyzes the components of the additives in the etching solution of the etching lower unit, and the potential measuring instrument monitors the potential of the etching solution of the etching lower unit.

The invention also provides a COF tape precise etching management and control system which comprises an etching upper unit, an etching lower unit, a recovery unit, a first liquid making unit, an additive stock solution unit, an acid stock solution unit, a first liquid conveying unit, a second liquid making unit and a strong oxidant stock solution unit, wherein the etching upper unit is connected with the etching lower unit through a pipeline, the recovery unit is respectively connected with the etching lower unit and the first liquid making unit through pipelines, the first liquid making unit is also respectively connected with the additive stock solution unit, the acid stock solution unit and the first liquid conveying unit through pipelines, the first liquid conveying unit is also connected with the etching lower unit through a pipeline, the second liquid conveying unit is respectively connected with the second liquid making unit and the etching lower unit through pipelines, the second liquid making unit is also connected with the strong oxidant stock solution unit, and the COF tape precise etching management and control system is respectively provided with a chemical analyzer for detecting the concentration of an etching additive in the etching lower unit and a potential measuring instrument for monitoring the potential of the etching liquid in the etching lower unit.

The invention also provides a COF tape precise etching control system which comprises an etching upper unit, an etching lower unit, a balance unit, a recovery unit, a first liquid making unit, an additive stock solution unit, an acid stock solution unit, a first liquid conveying unit, a second liquid making unit and a strong oxidant stock solution unit, wherein the etching upper unit is connected with the etching lower unit through a pipeline, the etching lower unit is horizontally communicated with the balance unit through a pipeline, the balance unit is also connected with the etching upper unit, the recovery unit is respectively connected with the etching lower unit and the first liquid making unit through pipelines, the first liquid making unit is also respectively connected with the additive stock solution unit, the acid stock solution unit and the first liquid conveying unit through pipelines, the first liquid conveying unit is also connected with the etching lower unit through a pipeline, the second liquid conveying unit is respectively connected with the second liquid making unit and the etching lower unit through a pipeline, the second liquid making unit is also connected with the strong oxidant stock solution unit, and the COF tape precise etching control system is also respectively provided with an etching liquid analyzer for detecting concentration of the additive in the etching lower unit and monitoring potential of the etching liquid.

The method greatly reduces the use of high-cost etching additives, controls the cost of the liquid medicine, and simultaneously reduces the influence on the environment and the cost of waste liquid treatment.

According to the invention, the content of the additive in the etching solution is analyzed through the high performance liquid chromatography, the additive addition amount is accurately controlled, and meanwhile, the potential of the potential etching solution is measured, so that the etching solution is ensured not to contain unreacted strong oxidant, and the influence of the strong oxidant on the additive is avoided.

Drawings

FIG. 1 is a schematic diagram of an etching control system according to the background art of the present invention;

FIG. 2 is a schematic cross-sectional view of a Cu wiring according to the background of the invention

FIG. 3 is a schematic flow chart of a tape precise etching management and control system according to embodiment 1 of the present invention;

FIG. 4 is a schematic flow chart of a COF tape precise etching control system according to an embodiment of the invention;

FIG. 5 is a schematic flow chart of an autonomous recovery system for an etching solution according to embodiment 3 of the present invention;

FIG. 6 is a graph showing the time-dependent trend of the additive in hydrogen peroxide solutions of different concentrations in the etching solution of the present invention.

Detailed Description

The invention will be further explained with reference to the drawings.

In the description of the present invention, it should be noted that the terms "upper", "lower", "bottom", "top", "length direction", "width direction", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or the orientations or positional relationships that the products of the present invention are conventionally placed in use, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should also be noted that, unless explicitly stated or limited otherwise, the terms "attached" and "connected" are to be interpreted broadly, e.g., "connected" may be a fixed connection, a detachable connection, or an integral connection; can be mechanically or electrically connected; the above terms may be directly connected, indirectly connected through an intermediate, soldered, or packaged, and the like, and those skilled in the art will understand the specific meaning of the above terms in the present invention.

The method comprises the steps of controlling the addition amount of a strong oxidant through potential analysis of an etching solution, and judging whether the strong oxidant exists in the etching solution or not by monitoring the potential of the etching solution.

According to the invention, whether hydrogen peroxide exists in the etching solution can be judged through potential analysis, the concentration of Cu + in the etching solution is controlled, the etching effect of the etching solution is ensured, the stability of the liquid medicine is ensured, and the product yield is improved.

Further, the COF tape precise etching control method further comprises the step of chemically analyzing the concentration of an additive solution, when the electric potential of the etching solution is in a high position, the concentration of the additive solution is chemically analyzed at regular intervals, and when the absolute difference value of two adjacent analysis results is out of a target range, copper powder is added until the electric potential is in a low position.

In the invention, during etching production, high performance liquid chromatography is used, the concentration of the additive in the etching solution is repeatedly analyzed every 12 hours, and the strong oxidant such as H in the etching solution is judged according to the results of the two analyses ₂ O ₂ Concentration (different hydrogen peroxide amount, different additive attenuation rate, trend graph of additive in hydrogen peroxide with different concentration along with time obtained according to earlier experiment-as figure 6, concentration of H2O2 is reversely deduced), deviation of two results is +/-2%, no operation is carried out within error range, if yes, H is reversely deduced ₂ O ₂ And (4) reducing the concentration of a strong oxidant such as hydrogen peroxide to the range of control by adding copper powder.

In the invention, the potential test principle is as follows:

nernst equation: e = E0+ (0.059/n) log ([ Cu2+ ]/[ Cu + ])

E: is the potential at a specific concentration

E0: standard potential

n: number of gain and loss electrons

[ Cu2+ ]: concentration of divalent copper ion

[ Cu + ]: concentration of monovalent copper ion

Further, in order to prevent the strong oxidant from reacting with a part of additives, the method for accurately etching and controlling the COF tape further comprises the steps of independently adding the strong oxidant into the etching solution of the etching tank, and adding the acid and the additives into the etching tank after the acid and the additives form the etching solution according to the proportion.

Based on the above-mentioned method for controlling the precise etching of the COF tape, the following embodiments 1 to 3 provide a system for controlling the precise etching of the COF tape.

Example 1

Referring to fig. 3, fig. 3 is a schematic view of a COF tape precise etching control system.

As shown in fig. 3, a COF tape precise etching control system includes an upper etching unit 20, a lower etching unit 1, an additive stock solution unit 5, an acid stock solution unit 6, and a strong oxidant stock solution unit 7, the upper etching unit 20 is connected to the lower etching unit 1 through a pipeline, and the additive stock solution unit 5, the acid stock solution unit 6, and the strong oxidant stock solution unit 7 are respectively connected to the lower etching unit 1.

In the present invention, the etching lower unit 1 receives the etching solution etched from the etching upper unit 20 (the etching solution flows into the bottom of the etching upper unit 20 after reacting with the etching of the COF and immediately flows out from the outlet at the bottom of the etching upper unit 20), thereby preventing the product quality defect caused by the over-etching of the COF due to the accumulated liquid of the etching solution in the etching upper unit 20.

In the present invention, the COF tape precise etching control system is further provided with a high performance liquid chromatograph 22 and a potential measuring instrument 23, respectively, the high performance liquid chromatograph 22 analyzes components in the etching solution of the etching lower unit 1, and the potential measuring instrument 23 measures the potential of the etching solution of the etching lower unit 1.

The COF tape accurate etching management and control system is used for COF etching production, the top width H1 and the bottom width H2 of a Cu circuit of an etched product are detected, and the detection result is shown in the following table I.

Comparative example 1

Compared with the embodiment 1, the present embodiment 1 is the same except that the COF tape precise etching control system does not include the potential measuring instrument 23, that is, the present embodiment does not perform the potential detection during the COF etching production, and cannot perform the corresponding adjustment according to the potential, and the production parameters, the process conditions, and the like related to the etching are completely the same as those of the embodiment 1. The top width H1 and the bottom width H2 of the Cu line of the etched product were measured, and the measurement results are shown in table one below.

TABLE-difference of Cu lines H2-H1

Example 2

Referring to fig. 4, fig. 4 is a schematic view of a COF tape precise etching control system.

As shown in fig. 4, a COF tape precise etching management and control system includes an upper etching unit 20, a lower etching unit 1, a recovery unit 2, a first liquid making unit 3, an additive stock solution unit 5, an acid stock solution unit 6, a first liquid sending unit 10, a second liquid sending unit 9, a second liquid making unit 8 and a strong oxidant stock solution unit 7, where the upper etching unit 20 is connected to the lower etching unit 1 through a pipeline, the recovery unit 2 is connected to the lower etching unit 1 and the first liquid making unit 3 through pipelines, the first liquid making unit 3 is further connected to the additive stock solution unit 5, the acid stock solution unit 6 and the first liquid sending unit 10 through pipelines, the first liquid sending unit 10 is further connected to the lower etching unit 1 through a pipeline, the second liquid sending unit 9 is connected to the second liquid making unit 8 and the lower etching unit 1 through a pipeline, and the second liquid making unit 8 is further connected to the strong oxidant stock solution unit 7.

In the invention, the COF tape precise etching management and control system is further provided with a high performance liquid chromatograph 22 and a potential measuring instrument 23 respectively, the high performance liquid chromatograph 22 analyzes components in the etching solution for etching the lower unit 1, and the potential measuring instrument 23 measures the potential of the etching solution for etching the lower unit 1.

In the present invention, the etching lower unit 1 receives the etching solution etched from the etching upper unit 20 (the etching solution flows into the bottom of the etching upper unit 20 and immediately flows out from the outlet at the bottom of the etching upper unit 20 after reacting with the etching of the COF), thereby preventing the product quality defect caused by the excessive etching of the COF in the etching upper unit 20 due to the accumulated solution of the etching solution.

In the invention, the recovery unit 2 receives the etching solution overflowed from the etching lower unit 1 and sends the etching solution to the first solution making unit 3 through a pipeline, and the recovery unit 2 is arranged because the amount of the supplementary solution (namely, the supplementary oxidation solution, the acid and the additive) is possibly larger than the actual consumption amount along with the continuous production in the production process, and the amount of the liquid in the etching lower unit 1 is gradually increased, which is not beneficial to precise management and control. By the arrangement of the recovery unit 2, the amount of etching liquid in the upper etching unit 20 is ensured to be stable.

In the invention, the first liquid making unit 3 receives the etching liquid from the recovery unit 2, receives the additive and the acid from the additive stock solution unit 5 and the acid stock solution unit 6 through the dosing pumps according to the sampling analysis result of the etching lower unit 1, pumps the mixed liquid to the first liquid conveying unit 10 after mixing, and then conveys the mixed liquid to the etching lower unit 1 through the first liquid conveying unit 10.

In the present invention, the second solution-making unit 8 concentrates or dilutes the commercial stock solution from the strong oxidant stock solution unit 7 to a concentration that meets the normal production requirements of the etching solution, and the concentration or dilution method is not particularly limited. The oxidizing liquid with the concentration meeting the normal production requirement of the etching liquid and manufactured by the second liquid manufacturing unit 8 is sent to the second liquid sending unit 9 through a pump, and the second liquid sending unit 9 supplements the amount of the oxidizing liquid to the unit 1 under etching through a quantitative pump according to the result of sampling analysis.

In the invention, the oxidizing solution is directly added into the etching lower unit 1, and the acid and the additive are firstly mixed with the etching solution from the recovery unit 2 through the first solution making unit 3, and then are added into the etching lower unit 1 through the first solution sending unit 10 after being mixed, on one hand, the difficulty of control is increased due to the simultaneous addition, and on the other hand, the reaction of the strong oxidant, the acid and the additive is prevented, so that the regeneration of the etching solution is influenced.

During etching production, the etching liquid is sent from the etching lower unit 1 to the spray pipe in the inner cavity of the etching upper unit 20 and sprayed onto the COF passing through the inner cavity of the etching upper unit 20 through the spray head arranged on the spray pipe, the COF is etched when the COF passes through the etching upper unit 20, the etched liquid flows to the bottom of the etching upper unit 20 and flows into the etching lower unit 1 through the outlet, enters the etching liquid autonomous recovery system to be regenerated back to the etching lower unit 1 and then is sent to the etching upper unit 20 again for etching, and the continuous stable production is repeated.

Example 3

Referring to fig. 5, fig. 5 is a schematic view of another COF tape precise etching control system.

As shown in fig. 5, a COF tape precise etching control system includes an etching upper unit 20, an etching lower unit 1, a balance unit 21, a recovery unit 2, a first liquid making unit 3, an additive stock solution unit 5, an acid stock solution unit 6, a first liquid sending unit 10, a second liquid sending unit 9, a second liquid making unit 8 and a strong oxidant stock solution unit 7, where the etching upper unit 20 is connected to the etching lower unit 1 through a pipeline, the etching lower unit 1 is horizontally communicated with the balance unit 21 through a pipeline, the balance unit 21 is further connected to the etching upper unit 20, the recovery unit 2 is respectively connected to the etching lower unit 1 and the first liquid making unit 3 through pipelines, the first liquid making unit 3 is further connected to the additive stock solution unit 5, the acid stock solution unit 6 and the first liquid sending unit 10 through pipelines, the first liquid sending unit 10 is further connected to the etching lower unit 1 through a pipeline, the second liquid sending unit 9 is respectively connected to the second liquid making unit 8 and the etching lower unit 1 through a pipeline, and the second strong oxidant stock solution unit 7.

In the invention, the recovery unit 2 receives the etching solution overflowing from the etching lower unit 1 and sends the etching solution to the first solution making unit 3 through a pipeline, and the recovery unit 2 is arranged because the amount of the supplementary solution (namely, the supplementary oxidation solution, the acid and the additive) is possibly larger than the actual consumption amount along with the continuous production in the production process, and the amount of the solution in the etching lower unit 1 is gradually increased, which is not beneficial to precise control. By the arrangement of the recovery unit 2, the amount of etching liquid in the upper etching unit 20 is ensured to be stable.

In the invention, the first liquid making unit 3 receives the etching liquid from the recovery unit 2, receives the additive and the acid from the additive stock solution unit 5 and the acid stock solution unit 6 through the dosing pumps according to the sampling analysis result of the etching lower unit 1, pumps the mixed liquid to the first liquid conveying unit 10 after mixing, and then conveys the first liquid conveying unit 10 to the etching lower unit 1.

In the present invention, the second liquid-making unit 8 concentrates or dilutes the commercial stock solution from the strong oxidant stock solution unit 7 to a concentration that meets the normal production requirements of the etching solution, and the concentration or dilution method is conventional and is not particularly limited herein. The oxidizing liquid with the concentration meeting the normal production requirement of the etching liquid manufactured by the second liquid manufacturing unit 8 is sent to the second liquid sending unit 9 through a pump, and the second liquid sending unit 9 supplements the amount of the oxidizing liquid to the etching lower unit 1 through a fixed displacement pump according to the result of sampling analysis.

In the invention, the oxidizing solution is directly added into the etching lower unit 1, and the acid, the first additive and the second additive are firstly mixed with the etching solution from the recovery unit 2 through the first solution making unit 3 and then added into the etching lower unit 1 through the first solution sending unit 10 after mixing, on one hand, the difficulty of management and control is increased due to the simultaneous addition, and on the other hand, the reaction of the strong oxidant, the acid, the first additive and the second additive is prevented, so that the regeneration of the etching solution is influenced.

In the invention, the balance unit 21 is arranged to ensure that most of the original etching solution after etching enters the recovery unit 2 for regeneration, and the supplemented oxidizing solution is firstly mixed with the etching solution supplemented with the additive and the acid in the etching lower unit 1, so that the liquid containing the supplemented solution, which is sent into the etching upper unit 20 from the balance unit 21 and enters the etching, is more uniformly mixed, the etching manufacturing capacity of COF is improved, and the perfect shape of a copper circuit is formed.

During etching production, etching liquid is sent to a spray pipe in the inner cavity of the upper etching unit 20 from the balance unit 21 and sprayed onto a COF passing through the inner cavity of the upper etching unit 20 through a spray head arranged on the spray pipe, the COF is etched when the COF passes through the upper etching unit 20, the etched liquid flows to the bottom of the upper etching unit 20 and flows into the lower etching unit 1 through an outlet to enter an etching liquid autonomous recovery system for regeneration back to the lower etching unit 1, then the lower etching unit 1 flows into the balance unit 21 and then is sent to the upper etching unit 20 again for etching, and the process is repeated and continuous and stable production is achieved.

Claims

1. A control method for COF tape accurate etching is disclosed, which comprises the steps of controlling the addition amount of a strong oxidant through the potential analysis of an etching solution, and judging whether the strong oxidant exists in the etching solution or not by monitoring the potential of the etching solution; the COF tape accurate etching control method further comprises the step of chemically analyzing the concentration of an additive, when the electric potential of the etching solution is in a high position, according to a trend graph of the additive changing along with time in strong oxidants with different concentrations obtained through earlier experiments, the concentration of the additive is chemically analyzed at regular intervals, the concentration of the strong oxidant is reversely deduced, and the strong oxidant is reduced to the control range in a copper powder adding mode.

2. The method for precisely etching and controlling a COF tape according to claim 1, wherein: the COF tape precise etching control method also comprises the steps that a strong oxidant is independently added into the etching solution of the etching groove, and the acid and the additive are firstly mixed with the etching solution outside the etching groove and then added into the etching solution of the etching groove along with the etching solution.