KR20120079414A - Method of plating for pcb - Google Patents

Method of plating for pcb Download PDF

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Publication number
KR20120079414A
KR20120079414A KR1020110000679A KR20110000679A KR20120079414A KR 20120079414 A KR20120079414 A KR 20120079414A KR 1020110000679 A KR1020110000679 A KR 1020110000679A KR 20110000679 A KR20110000679 A KR 20110000679A KR 20120079414 A KR20120079414 A KR 20120079414A
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KR
South Korea
Prior art keywords
plating
thickness
plated
printed circuit
circuit board
Prior art date
Application number
KR1020110000679A
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Korean (ko)
Inventor
이창보
최철호
Original Assignee
삼성전기주식회사
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Publication date
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Priority to KR1020110000679A priority Critical patent/KR20120079414A/en
Publication of KR20120079414A publication Critical patent/KR20120079414A/en

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/04—Electroplating with moving electrodes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
    • H05K3/18—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material
    • H05K3/188—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material by direct electroplating
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/24—Reinforcing the conductive pattern
    • H05K3/241—Reinforcing the conductive pattern characterised by the electroplating method; means therefor, e.g. baths or apparatus
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/07—Treatments involving liquids, e.g. plating, rinsing
    • H05K2203/0703—Plating
    • H05K2203/0723—Electroplating, e.g. finish plating

Abstract

PURPOSE: A method for plating a printed circuit board is provided to uniformly form a thickness of a plated layer formed on a printed circuit board because a plating thickness control value is controlled by a feedback control. CONSTITUTION: A plating thickness control value is set before progressing a plating process(S101). A printed circuit board is dipped in a plating device. A plating layer is formed in an object by applying a voltage(S102). A thickness, a plating speed, a plating speed change rate, and a plated amount of the plated layer are measured(S103). The measured thickness of the plated layer is compared to required thickness uniformity(S104). A proper plating thickness control value is re-set(S105). The plating thickness control value sets the thickness of the plated layer formed on the object.

Description

Plating method of printed circuit boards {METHOD OF PLATING FOR PCB}

The present invention relates to a plating method of a printed circuit board, and more particularly, to a plating method of a printed circuit board capable of making the thickness of the plating layer uniform through feedback control.

Printed Circuit Boards (PCBs) serve to electrically connect semiconductor chips and allow various semiconductor chips to be installed on the substrate. A printed circuit board is generally composed of a substrate and a conductive circuit formed on the surface of the substrate. To form the conductive circuit, a copper plating process of forming a plating layer having a thickness of about 1 μm on the surface of the printed circuit board is performed. This can be done.

This copper plating process is largely divided into two types, one is chemical copper plating and the other is electroplating (or electroplating). Electrolytic copper plating has an advantage of being plated faster than chemical copper plating, but has a disadvantage in that it is not uniformly plated on the entire substrate due to the difference in current strength for each position.

That is, in the conventional plating apparatus, a negative potential is applied from the cathode to the outer peripheral portion of the to-be-plated body, and a potential difference is generated between the center portion and the outer peripheral portion of the to-be-plated body. It concentrates on the outer peripheral portion of the plated body. Here, the thickness of the plated film plated on the plated body is proportional to the current flowing from the anode to the surface of the plated body, that is, the metal ion attracted from the anode to the surface of the plated body, and therefore the current flowing from the anode toward the plated body. If the density is concentrated on the outer circumferential portion of the plated body, the thickness of the plated film deposited on the central portion of the plated body becomes thick, which may cause a problem of inferior uniformity of the plated film formed on the plated body.

In order to solve such a nonuniformity in the thickness of the plating film during electroplating, two kinds of methods are used. One is to arrange the current distribution as evenly as possible by providing a dummy copper region so as to reduce the current bias due to the size or shape of the seed layer copper for plating in the printed circuit board.

The other is to uniformly distribute the current by applying various methods to the plating vessel, such as an alternating current plating method, a substrate vibration plating method, and the like.

The alternating current plating method controls the plating thickness by appropriately applying an alternating current other than direct current to a plurality of electrode probes connected to a printed circuit board according to the type and shape of the substrate. The substrate vibrating plating method is a method of controlling the plating thickness by moving the substrate at an appropriate speed in the plating bath to reduce the concentration variation of the plating liquid.

However, these methods are performed by measuring the thickness of the plated plating film after proceeding with a one-way solution without a feedback control concept. As a result, when the distance between the anode electrode and the cathode electrode is incorrectly calculated, the actual plating thickness and the target plating thickness may be greatly different, and the plating is performed without measuring the thickness of the plating film in real time. There is a problem that the thickness of the uniform plating film cannot be obtained.

On the other hand, after measuring the thickness of the plated plated film, the method of plating by setting the plating set value again may be considered, in this case, by measuring the thickness of the plated plated by hand, then feeding back the plating set value again There is a problem that the time required until the productivity is lowered.

The present invention has been proposed to solve the above problems, and it is a technical problem to provide a plating method of a printed circuit board capable of uniformizing the thickness of the plating layer through feedback control.

In order to achieve the above object, according to an embodiment of the present invention, in the method for plating the surface of a printed circuit board by the electroplating method, (a) plating thickness to determine the thickness of the plating film formed on the plated body Setting a control value; (b) forming a plated film on the plated body by using a plating apparatus; (c) measuring, in real time, the thickness of the plated film formed on the plated body, the rate of plating, the rate of change of plating, and the amount of plating; (d) determining whether the measured thickness of the plated film is suitable for the required uniformity; And (e) resetting the plating thickness control value to match the required uniformity if it is determined that the measured thickness of the plating film is not suitable for the required uniformity, and then branching to the step (b). It provides a plating method of a printed circuit board.

In addition, the method of measuring the thickness of the plated film in the step (c) is the plating of the printed circuit board, characterized in that by measuring the resistance value of the plated film formed on the plated body, converting the measured resistance value to the thickness value Provide a method.

In addition, the step (e) provides a plating method of the printed circuit board, characterized in that made through the PID control method according to the plated rate, the rate of change of the plated rate, the plated amount measured in the step (c).

In addition, when the thickness of the plated film measured in step (d) is suitable for the required uniformity, it provides a plating method of the printed circuit board, characterized in that the plating process is terminated without branching to the step (e).

According to the present invention, the plating thickness control value can be adjusted through feedback control to make the thickness of the plating film formed on the printed circuit board uniform.

1 is a flow chart showing a process performed according to the plating method of a printed circuit board according to the present invention.

Hereinafter, the present invention will be described in detail with reference to embodiments of the present invention shown in the accompanying drawings. However, the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention. Accordingly, the shapes and sizes of the elements in the drawings may be exaggerated for clarity of description, and the elements denoted by the same reference numerals in the drawings are the same elements.

1 is a flowchart illustrating a process performed according to a plating method of a printed circuit board according to the present invention.

Referring to FIG. 1, in the plating method of a printed circuit board according to the present invention, a plating thickness control value for determining a thickness of a plating film formed on a plated body is set, and a plating film is formed on the plated body using a plating apparatus. Measuring the thickness of the plated film formed on the plated body and the plated speed, the rate of change of the plated rate, the amount of plated in real time, determining whether the measured thickness of the plated film is suitable for the required uniformity, and measured If it is determined that the thickness of the plating film is not suitable for the required uniformity, the method may include resetting the plating thickness control value to match the required uniformity, and then branching to forming the plating film.

Before proceeding with the plating process, a step of setting a plating thickness control value is performed (S101). Here, the plating thickness control value is a control value set to determine the thickness of the plating film formed on the plated body by the electrolytic plating process, which will be described in detail in the step of resetting the plating thickness control value described later.

After setting the plating thickness control value, a step of forming a plated film on the plated body by immersing the plated body, for example, a printed circuit board, in a plating apparatus (not shown) and applying a voltage after a predetermined time. Proceed (S102).

Here, the plating apparatus includes a plating vessel containing a solution having a constant width and a relatively long length, and a positive current flowing through the positively charged terminal, an electrolytic cell cathode for applying a negative potential to the printed circuit board, It may be composed of an electrolytic cell anode. In other words, the plated body to be plated is introduced into the plating solution, the plated body is used as a cathode, and the metal to be electrodeposited is used as an anode to conduct electricity to plate the desired metal ions. A plating film can be formed by making it precipitate on the surface of a sieve.

On the other hand, when the object to be plated has conductivity, plating is possible by directly using the plated body as a cathode. However, when the plated body is formed of an insulating material such as a circuit board, a seed layer is formed on the insulating material as an electrode of electroplating by electroless chemical plating. Next, a plating film may be formed by performing electroplating with the electrode.

However, as described above, since the uniform current is not easily supplied to the entire plated body, there may be a problem that the thickness uniformity of the plated film is not high. Accordingly, in the plating method according to the present invention, in order to improve the uniformity of the thickness of the plated film formed on the plated body, it is intended to provide a plating method capable of uniformizing the thickness of the plated layer through feedback control.

To this end, when the plated film is formed on the plated body by the plating apparatus, the thickness of the formed plated film and the plated speed, the rate of change of the plated rate, and the amount of plated are measured (S103).

Here, a method of measuring the resistance value of the plated film formed on the plated body as a method of measuring the thickness of the plated film, and then converting the measured resistance value into a thickness value can be used, measuring the thickness of the plated film As an example of the apparatus, an apparatus disclosed in MGAGE (product name) manufactured by KLA-TENCOR company or Korean Patent Publication No. 2000-4560 can be used.

After the thickness of the plated film is measured, the process of determining whether the measured thickness of the plated film is suitable for the required uniformity is carried out (S104), and when it is determined that it is not suitable, the plating thickness control value is reset to match the required uniformity. In step S102, the process proceeds to the step S105.

Here, the plating thickness control value is a value for determining the thickness of the plating film formed on the plated body in the operation of the plating apparatus, specifically, the amount of current supplied by the electrolytic cell anode and the electrolytic cell cathode, the plated body is immersed in the plating tank Time, and the mixing strength of the plating liquid contained in the plating bath, the interval between the electrolytic cell cathode and the electrolytic cell anode, and the amount of current can be adjusted by pulse or voltage.

However, in order to uniformly form the thickness of the plating film, the plating thickness control value should be feedback-controlled according to the plating rate, the rate of change of the plating rate, and the plating amount measured in step S103. One embodiment of the present invention Can provide feedback control through PID control method.

The PID control method is a kind of feedback control that maintains the output value based on the error between the control variable and the reference input. Proportional (P) control and Proportional-Integral (I) control and proportional derivative (Proportional- Derivative: D) is a combination of controls. Here, the proportional control multiplies the error signal between the reference signal and the current signal by an appropriate proportional constant gain to produce a control signal. Proportional integral control uses integral control in parallel to proportional control, which integrates an error signal to produce a control signal. Proportional derivative control uses derivative control in parallel to proportional control to differentiate the error signal to produce a control signal. That is, the standard PID control method is configured to calculate the control value, that is, the thickness of the plating film by adding three terms as shown in Equation 1 below.

Figure pat00001

Therefore, the plated film formed on the plated body is formed by using the current plating speed as proportional control (P), the current plating speed change rate as proportional integral control (I), and the current plating amount as a gain value of the proportional differential control (D). The thickness can be determined. That is, when the thickness of the plated layer is measured by using the resistance value as described above, the gain value is estimated, and then the thickness of the plated film can be controlled by determining a function of the plating thickness control value according to the estimated gain value. have.

As described above, the thickness of the plating film is measured in real time using the resistance value of the plating film formed on the plated body to determine whether the thickness of the plating film is suitable for the required uniformity, and when it is determined that the thickness of the plating film is not uniform, PID control. By plating by controlling the thickness of the plated film in a subsequent plating process through the method, it is possible to form a plated film having improved uniformity compared to the plated film formed according to the conventional plating method.

On the other hand, if it is determined that the thickness of the plated film measured in step S104 is suitable for the required uniformity, the plating process may be terminated without branching to step S105.

The present invention is not limited by the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims, and various forms of substitution, modification and It will be apparent to those skilled in the art that changes are possible.

S101: plating thickness control value setting step
S102: electrolytic plating progress step
S103: Plating Film Thickness Measurement Step
S104: Uniformity Determination Step
S105: Plating Thickness Control Value Reset Step

Claims (4)

In the method of plating the surface of a printed circuit board by the electroplating method,
(a) setting a plating thickness control value for determining a thickness of the plating film formed on the plated body;
(b) forming a plated film on the plated body by using a plating apparatus;
(c) measuring, in real time, the thickness of the plated film formed on the plated body, the rate of plating, the rate of change of plating, and the amount of plating;
(d) determining whether the measured thickness of the plated film is suitable for the required uniformity; And
(e) if it is determined that the measured thickness of the plating film is not suitable for the required uniformity, resetting the plating thickness control value to suit the required uniformity, and then branching to the step (b);
Plating method of a printed circuit board comprising a.
The method of claim 1,
The method of measuring the thickness of the plated film in the step (c) is a plating method for a printed circuit board, characterized in that by measuring the resistance value of the plated film formed on the plated body, and then converting the measured resistance value to the thickness value.
The method of claim 1,
Wherein step (e) is a plating method of a printed circuit board, characterized in that made through the PID control method according to the plated rate, the rate of change of the plated rate, the plated amount measured in step (c).
The method of claim 1,
If the thickness of the plated film measured in step (d) is suitable for the required uniformity, the plating process is terminated without branching to step (e).
KR1020110000679A 2011-01-04 2011-01-04 Method of plating for pcb KR20120079414A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20170037066A (en) * 2015-09-25 2017-04-04 최대규 Apparatus and method for electroplating
CN112198195A (en) * 2020-09-10 2021-01-08 广州兴森快捷电路科技有限公司 Method and device for detecting quality of plating layer in PCB hole and storage medium

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20170037066A (en) * 2015-09-25 2017-04-04 최대규 Apparatus and method for electroplating
CN112198195A (en) * 2020-09-10 2021-01-08 广州兴森快捷电路科技有限公司 Method and device for detecting quality of plating layer in PCB hole and storage medium

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