JP3753815B2 - Method for measuring metal ion concentration in electroless plating solution - Google Patents

Method for measuring metal ion concentration in electroless plating solution Download PDF

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Publication number
JP3753815B2
JP3753815B2 JP30167396A JP30167396A JP3753815B2 JP 3753815 B2 JP3753815 B2 JP 3753815B2 JP 30167396 A JP30167396 A JP 30167396A JP 30167396 A JP30167396 A JP 30167396A JP 3753815 B2 JP3753815 B2 JP 3753815B2
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Prior art keywords
plating solution
output
metal ion
electroless plating
ion concentration
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JP30167396A
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JPH10142144A (en
Inventor
秀逸 西中
泰光 森下
直樹 宮川
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Chuo Seisakusho KK
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Chuo Seisakusho KK
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Priority to JP30167396A priority Critical patent/JP3753815B2/en
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Description

【０００１】
【発明の属する技術分野】
本発明は、吸光光度法による無電解めっき液の金属イオン濃度測定方法に関するものである。
【０００２】
【従来の技術】
無電解ニッケルめっき等の無電解めっきでは、めっき液中の金属イオンがワーク金属の触媒還元反応によりワーク表面に金属として析出し、それにつれて金属イオン濃度、還元剤濃度、pH等が徐々に低下して行く。そのため、めっき液をサンプリングして吸光光度法により金属イオン濃度を測定し、めっき液中の金属イオン量等を常に定められた値に保つめっき液管理が行われている。
【０００３】
この吸光光度法による金属イオン濃度測定は、図３に示すように無電解めっき液をフローセル１の内部に導き、光源２から光を当ててフォトセンサー３により透過した光量を測定する方法で行われている。光源２からの投光量をL0とし、フォトセンサー３により測定された透過光量をL1としたとき、ｔ＝L1/L0 を透過率といい、Ｅ＝log(1/t)を吸光度という。この場合一般に吸光度Ｅは金属イオン濃度に正比例するので、吸光度Ｅから無電解めっき液中の金属イオン濃度を求めることができる。
【０００４】
従来は図３に示すように、光源２の近傍に配置されたフォトセンサー４により投光量L0を常時検出してこの投光量L0が一定となるように光源電力制御器５で光源２に加える電力を制御していた。このように投光量L0を一定に制御しているため、ＣＰＵ７はプリアンプ６で増幅されたフォトセンサー３の出力のみに基づいて透過率ｔを演算することができる。ところがめっき液濃度が高くなり透過率が低下すると透過光量L1の絶対値が小さくなるため、フォトセンサー３の出力は微小となる。従って、Ｅ＝log(1/t)として算出される吸光度Ｅの値の誤差は、めっき液濃度が低い場合に比較して大きくなるという問題があった。
【０００５】
【発明が解決しようとする課題】
本発明は上記した従来の問題点を解決し、めっき液濃度が高くなり透過率が低下した場合にも、めっき液濃度が低い場合と同様に精度良く金属イオン濃度の測定ができる無電解めっき液の金属イオン濃度測定方法を提供するためになされたものである。
【０００６】
【課題を解決するための手段】
上記の課題を解決するためになされた本発明は、無電解めっき液の金属イオン濃度を吸光光度法により測定する無電解めっき液の金属イオン濃度測定方法であって、実使用時の定常の最高金属イオン濃度以下の場合に無電解めっき液が導かれるフローセルの透過光を受光するフォトセンサーの出力が光源からの投光量を検出するフォトセンサーの出力より大きく、最大出力近くになるようにしておき、フローセルの透過光を受光するフォトセンサーの出力と、光源からの投光量を検出するフォトセンサーの出力とを比較して大きい方の信号を選択し、選択された信号が一定に保たれるように光源の出力を制御して、測定を行うことを特徴とするものである。
【０００７】
【発明の実施の形態】
〔第１の実施形態〕
図１は本発明の第１の実施形態を示す図であり、従来例と同様、１は無電解めっき液が導かれるフローセル、２はＬＥＤ等の光源、３は透過光を受光するフォトセンサー、４は光源２の近傍に配置されたフォトセンサー、５は光源電力制御器である。フォトセンサー３の出力はプリアンプ６で増幅されたうえでＣＰＵ７に入力され、またフォトセンサー４の出力もプリアンプ８で増幅されたうえでＣＰＵ７に入力される。ＣＰＵ７は投光量L0と透過光量L1からｔ＝L1/L0 の式により透過率ｔを演算する。
【０００８】
前記したようにめっき液濃度が高くなると透過率が低下し透過光量L1が減少するが、本発明においてはＣＰＵ７が演算した透過率ｔが低下したとき、ＣＰＵ７から光源電力制御器５に信号を送り、光源２に供給する電力を増し投光量L0を増加させる。このため、透過率が低下したときにも透過光量L1の絶対値が増加するので、従来のように吸光度Ｅの誤差がめっき液濃度が低い場合に比較して大きくなることはない。
【０００９】
〔第２の実施形態〕
図２は本発明の第２の実施形態を示す図である。この実施形態では、無電解めっき液が導かれるフローセル１の透過光を受光するフォトセンサー３の出力Ａと、光源２からの投光量L0を検出するフォトセンサー４の出力Ｂとが比較器９で比較され、高位選択スイッチ１０が大きい方の信号を選択する。そして選択された信号が一定に保たれるように光源電力制御器５に制御信号が送られ、光源２の出力を制御する。
【００１０】
この実施形態では、実使用時の定常の最高金属イオン濃度以下の場合、フォトセンサー３の出力Ａがフォトセンサー４の出力Ｂより大きくなり、最大出力近くになるように設計しておく。実使用時の定常の最高金属イオン以下の場合には、第１の実施形態と同様に、透過光を受光するフォトセンサー３の出力Ａが一定になるように光源電力制御器５が光源２の投光量を制御するので、吸光度の測定誤差を小さくすることができる。また金属イオン濃度が定常の最高濃度以上となり、フォトセンサー３の出力Ａよりフォトセンサー４の出力Ｂが大きくなると高位選択スイッチ１０が出力Ｂを選択し、光源２からの投光量L0を検出するフォトセンサー４の出力Ｂが一定になるように光源２の出力が制御される。これによってフォトセンサー４の出力Ｂは飽和しないので測定回路のダイナミックレンジを有効に活用することができ、実使用時の測定精度を向上させることができる。
【００１１】
【発明の効果】
以上に説明したように、本発明によれば無電解めっき液の透過率が低下したときに光源の出力を高め、投光量を増加させて測定を行うようにしたので、透過光量の減少に伴う測定精度の低下が防止でき、無電解めっき液の濃度変化にかかわらず安定した精度で金属イオン濃度を測定できる利点がある。
【図面の簡単な説明】
【図１】第１の実施形態を示すブロック図である。
【図２】第２の実施形態を示すブロック図である。
【図３】従来法を示すブロック図である。
【符号の説明】
１ 無電解めっき液が導かれるフローセル
２ 光源
３ 透過光を受光するフォトセンサー
４ 投光量L0を検出するフォトセンサー
５ 光源電力制御器
６ プリアンプ
７ ＣＰＵ
８ プリアンプ
９ 比較器
１０ 高位選択スイッチ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for measuring a metal ion concentration of an electroless plating solution by an absorptiometric method.
[0002]
[Prior art]
In electroless plating such as electroless nickel plating, metal ions in the plating solution are deposited as metal on the workpiece surface by the catalytic reduction reaction of the workpiece metal, and the metal ion concentration, reducing agent concentration, pH, etc. gradually decrease accordingly. Go. Therefore, plating solution management is performed in which the plating solution is sampled, the metal ion concentration is measured by an absorptiometric method, and the amount of metal ions and the like in the plating solution is always set to a predetermined value.
[0003]
The metal ion concentration measurement by this absorptiometry is performed by a method in which an electroless plating solution is guided into the flow cell 1 as shown in FIG. 3 and the amount of light transmitted through the photosensor 3 is measured by applying light from the light source 2. ing. When the amount of light emitted from the light source 2 is L 0 and the amount of transmitted light measured by the photosensor 3 is L 1 , t = L 1 / L 0 is called transmittance, and E = log (1 / t) is absorbance. That's it. In this case, since the absorbance E is generally directly proportional to the metal ion concentration, the metal ion concentration in the electroless plating solution can be determined from the absorbance E.
[0004]
As shown in FIG. 3 conventionally by photosensor 4 placed in the vicinity of the light source 2 by detecting the projection amount L 0 constantly light 2 by the light source power controller 5 as the projection amount L 0 is constant The power to be applied was controlled. Thus, since the light projection amount L 0 is controlled to be constant, the CPU 7 can calculate the transmittance t based only on the output of the photosensor 3 amplified by the preamplifier 6. However, when the plating solution concentration increases and the transmittance decreases, the absolute value of the transmitted light amount L 1 decreases, and the output of the photosensor 3 becomes minute. Therefore, there is a problem that an error in the value of the absorbance E calculated as E = log (1 / t) becomes larger than when the plating solution concentration is low.
[0005]
[Problems to be solved by the invention]
The present invention solves the above-mentioned conventional problems, and even when the plating solution concentration increases and the transmittance decreases, the electroless plating solution can measure the metal ion concentration with high accuracy in the same manner as when the plating solution concentration is low. It is made in order to provide the metal ion concentration measuring method of this.
[0006]
[Means for Solving the Problems]
The present invention has been made to solve the above problems is a metal ion concentration measuring method of the electroless plating solution for measuring the concentration of metal ions in an electroless plating solution by spectrophotometry, the best steady in actual use Make sure that the output of the photosensor that receives the transmitted light of the flow cell through which the electroless plating solution is guided when the concentration is below the metal ion concentration is greater than the output of the photosensor that detects the amount of light emitted from the light source and close to the maximum output. Compare the output of the photo sensor that receives the light transmitted through the flow cell with the output of the photo sensor that detects the amount of light emitted from the light source, and select the larger signal so that the selected signal is kept constant. Further, the measurement is performed by controlling the output of the light source.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
FIG. 1 is a diagram showing a first embodiment of the present invention. Like the conventional example, 1 is a flow cell through which an electroless plating solution is guided, 2 is a light source such as an LED, 3 is a photosensor that receives transmitted light, 4 is a photosensor arranged in the vicinity of the light source 2, and 5 is a light source power controller. The output of the photosensor 3 is amplified by the preamplifier 6 and input to the CPU 7, and the output of the photosensor 4 is also amplified by the preamplifier 8 and input to the CPU 7. The CPU 7 calculates the transmittance t from the light projection amount L 0 and the transmitted light amount L 1 by the equation of t = L 1 / L 0 .
[0008]
As described above, when the plating solution concentration increases, the transmittance decreases and the transmitted light amount L 1 decreases. However, in the present invention, when the transmittance t calculated by the CPU 7 decreases, a signal is sent from the CPU 7 to the light source power controller 5. The electric power supplied to the light source 2 is increased and the light projection amount L 0 is increased. Therefore, the absolute value of the amount of transmitted light L 1 even when the transmittance is decreased to increase, not an error of the conventional way absorbance E is increased as compared to the case of a low plating solution concentration.
[0009]
[Second Embodiment]
FIG. 2 is a diagram showing a second embodiment of the present invention. In this embodiment, the output A of the photosensor 3 that receives the transmitted light of the flow cell 1 through which the electroless plating solution is guided and the output B of the photosensor 4 that detects the light projection amount L 0 from the light source 2 are compared with each other. And the higher level selection switch 10 selects the larger signal. Then, a control signal is sent to the light source power controller 5 so that the selected signal is kept constant, and the output of the light source 2 is controlled.
[0010]
In this embodiment, it is designed so that the output A of the photosensor 3 is larger than the output B of the photosensor 4 and is close to the maximum output when it is below the steady maximum metal ion concentration during actual use. In the case of less than the steady maximum metal ion in actual use, the light source power controller 5 is connected to the light source 2 so that the output A of the photosensor 3 that receives the transmitted light is constant, as in the first embodiment. Since the amount of emitted light is controlled, the measurement error of absorbance can be reduced. When the metal ion concentration is higher than the steady maximum concentration and the output B of the photosensor 4 is larger than the output A of the photosensor 3, the high-level selection switch 10 selects the output B and detects the light projection amount L 0 from the light source 2. The output of the light source 2 is controlled so that the output B of the photosensor 4 becomes constant. As a result, the output B of the photosensor 4 is not saturated, so that the dynamic range of the measurement circuit can be used effectively, and the measurement accuracy during actual use can be improved.
[0011]
【The invention's effect】
As described above, according to the present invention, when the transmittance of the electroless plating solution is lowered, the output of the light source is increased and the light projection amount is increased to perform the measurement. There is an advantage that the measurement accuracy can be prevented from being lowered and the metal ion concentration can be measured with stable accuracy regardless of the concentration change of the electroless plating solution.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment.
FIG. 2 is a block diagram showing a second embodiment.
FIG. 3 is a block diagram showing a conventional method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Flow cell to which electroless plating solution is guided 2 Light source 3 Photosensor that receives transmitted light 4 Photosensor that detects the amount of emitted light L 0 Light source power controller 6 Preamplifier 7 CPU
8 Preamplifier 9 Comparator 10 High-level selection switch

Claims (1)

無電解めっき液の金属イオン濃度を吸光光度法により測定する無電解めっき液の金属イオン濃度測定方法であって、実使用時の定常の最高金属イオン濃度以下の場合に無電解めっき液が導かれるフローセルの透過光を受光するフォトセンサーの出力が光源からの投光量を検出するフォトセンサーの出力より大きく、最大出力近くになるようにしておき、フローセルの透過光を受光するフォトセンサーの出力と、光源からの投光量を検出するフォトセンサーの出力とを比較して大きい方の信号を選択し、選択された信号が一定に保たれるように光源の出力を制御して、測定を行うことを特徴とする無電解めっき液の金属イオン濃度測定方法。A method for measuring the metal ion concentration of an electroless plating solution by measuring the metal ion concentration of the electroless plating solution by an absorptiometric method, in which the electroless plating solution is guided when it is below the steady maximum metal ion concentration in actual use The output of the photo sensor that receives the transmitted light of the flow cell is larger than the output of the photo sensor that detects the amount of light emitted from the light source, and is close to the maximum output, the output of the photo sensor that receives the transmitted light of the flow cell, Compare the output of the photo sensor that detects the amount of light emitted from the light source, select the larger signal, and control the output of the light source so that the selected signal is kept constant. A method for measuring a metal ion concentration of an electroless plating solution.
JP30167396A 1996-11-13 1996-11-13 Method for measuring metal ion concentration in electroless plating solution Expired - Fee Related JP3753815B2 (en)

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JP30167396A JP3753815B2 (en) 1996-11-13 1996-11-13 Method for measuring metal ion concentration in electroless plating solution

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Application Number Priority Date Filing Date Title
JP30167396A JP3753815B2 (en) 1996-11-13 1996-11-13 Method for measuring metal ion concentration in electroless plating solution

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JP3753815B2 true JP3753815B2 (en) 2006-03-08

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Cited By (1)

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KR101808255B1 (en) * 2016-04-22 2017-12-13 (주) 테크로스 Apparatus and method for measuring concentration using absorption photometry

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JP4654534B2 (en) * 2000-05-22 2011-03-23 上村工業株式会社 Automatic analysis and management equipment for electroless composite nickel plating solution
US20030049169A1 (en) * 2000-05-22 2003-03-13 Tadashi Chiba Automatic analyzing/controlling device for electroless composite plating solution
KR100414550B1 (en) * 2001-09-20 2004-01-13 주식회사 아큐텍반도체기술 A system and a method for analyzing concentrations of multi components solution
JP2008032719A (en) * 2006-07-31 2008-02-14 Applied Materials Inc Raman spectroscopy as integrated chemical measurement
WO2014192554A1 (en) * 2013-05-29 2014-12-04 コニカミノルタ株式会社 Illumination device and reflection-characteristics measurement device
JP2017203669A (en) * 2016-05-11 2017-11-16 株式会社中央製作所 Metal ion concentration measurement device of electroless plating liquid

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101808255B1 (en) * 2016-04-22 2017-12-13 (주) 테크로스 Apparatus and method for measuring concentration using absorption photometry

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