EP0897998B1 - Bain de nickel reducteur - Google Patents

Bain de nickel reducteur Download PDF

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Publication number
EP0897998B1
EP0897998B1 EP98114391A EP98114391A EP0897998B1 EP 0897998 B1 EP0897998 B1 EP 0897998B1 EP 98114391 A EP98114391 A EP 98114391A EP 98114391 A EP98114391 A EP 98114391A EP 0897998 B1 EP0897998 B1 EP 0897998B1
Authority
EP
European Patent Office
Prior art keywords
bath
nickel
concentration
stabiliser
complexing agent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP98114391A
Other languages
German (de)
English (en)
Other versions
EP0897998A2 (fr
EP0897998A3 (fr
Inventor
Renate Dr. Freudenberger
Walter Macht
Heidemarie Stiesch
Erwin Marka
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Doduco Contacts and Refining GmbH
Original Assignee
AMI Doduco GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by AMI Doduco GmbH filed Critical AMI Doduco GmbH
Publication of EP0897998A2 publication Critical patent/EP0897998A2/fr
Publication of EP0897998A3 publication Critical patent/EP0897998A3/fr
Application granted granted Critical
Publication of EP0897998B1 publication Critical patent/EP0897998B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/31—Coating with metals
    • C23C18/32—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron
    • C23C18/34—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents
    • C23C18/36—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents using hypophosphites

Definitions

  • the invention relates to an aqueous. acidic, reductively separating bath for electroless separation of Nickei.
  • nickel / gold adhesion requires a nickel layer that is as pure as possible, whereby a phosphorus content of less than 10% is desirable.
  • the well-known nickel baths contain the nickel to be deposited in the form of nickel sulfate or nickel chloride. The nickel present as a cation must be reduced for the purpose of its deposition become. This task is performed by sodium hypophoshite.
  • As a complexing agent for the nickel are lemon, glycol. Milk, apple, vinegar, amino vinegar. Propion. Succinic acid, ammonium, sodium, sodium hydroxyacetate, sodium citrate. Sodium glyconate, hydroxylamine sulfate and mixtures of some of these acids known.
  • TU Thiourea
  • Stabilizers needed. Lead, tin, arsenic and molybdenum compounds are known. However, the stabilizer reduces the deposition rate.
  • a disadvantage of the known baths is that in order to achieve acceptable separation rates, the bath must be operated at relatively high temperatures of over 90 ° C. At these temperatures, the thiourea is no longer sufficiently stable and its effects are no longer fully effective. To maintain the deposition rate, thiourea must therefore be added continuously. There is a gradual accumulation of the decomposition products of the thiourea in the bath and thus an increased deposition of sulfur in the nickel layer. This makes the deposited nickel layer less noble. This leads to an increased occurrence of corrosion after the exchange gold coating, in particular to pitting corrosion in holes in the printed circuit board. The corrosion values deteriorate with increasing bath age, since more and more thiourea has to be added. to maintain the deposition rate.
  • MTO is derived from M etal T urn - O ver. that is, all of the nickel contained in the bath can only be reacted five times until the bath must be discarded.
  • the present invention is based on the object of finding a composition for a bath of the type mentioned at the outset, with which a high-quality nickel layer formation with as few foreign deposits as possible is possible over a longer lifespan of the bath with a constant deposition rate.
  • the limits for the complexing agent are chosen so that at the lower limit all of the nickel can still be complexed during the concentration exceeding the upper limit would be uneconomical.
  • the accelerators used in the invention especially the thiourea derivative. are thermally more stable and more efficient than the accelerators previously used. This enables both the concentration of the accelerator and to keep the concentration of the stabilizer lower than before This has the advantage that fewer decomposition products are produced in the bath than before. especially the concentration of the accelerator and the one following it Concentration of the stabilizer can be lower from the outset than in State of the art. This not only leads to a longer lifespan, but also also for better controllability of the bathroom. First experiences show that lifetimes of up to 8 MTO are achieved with baths according to the invention become.
  • the accelerator should be in 1 to 3 times the molar concentration of the stabilizer be included in the bathroom. Will the relationship between stabilizer and accelerator shifted towards the stabilizer, inhibition of Conductor edges and drill holes. If there is an excess of accelerator, it can increase Pitting corrosion occurs.
  • the acidic character of the nickel bath is due to the carbon and hydroxy carboxylic acids certainly; the pH value is expedient by adding ammonia set to a value between 5 and 6.
  • a certain buffer effect occurs through the complexing agent used. Over time it will Bath is becoming increasingly acidic due to the chemical process If the pH drops too much off, it is raised again by adding ammonia.
  • Hypophosphite unfolds its reducing effect in the weakly acidic range. At a pH above 6 the reducing effect of the hypophosphite decreases. The same thing applies to a pH below 5. The hypophosphite reaches its optimum reducing effect for pH values between 4.6 and 5.5.
  • the present bathroom is very well suited to printed circuit boards with a noble nickel adhesive layer with a Coating phosphorus content less than 10%.
  • a subsequent one Coating the noble nickel layer with an exchange gold layer causes one Reduction of corrosion compared to a less noble one - coated with gold - Nickel layer.
  • the exchange gold bath can be in a wide pH range be driven between 5.5 and 6.5.
  • the bath temperature is expediently between 80 ° and 90 ° C., preferably a temperature of 85 ° to 90 ° C. is maintained in these temperature ranges one particularly economical deposition rates.
  • the accelerator is above 90 ° C increasingly decomposes and foreign atoms in the bathroom accumulate then can be deposited together with the nickel and pitting could cause.
  • a specifically complexing the stabilizer Complexing agent is added.
  • This is preferably the case to methylglycine diacetic acid, preferably in a concentration ratio from 0.5 to 5 ml per liter of bath liquid is added.
  • This prevents that the cation of the stabilizer fails and preferentially on edges or Drilled holes.
  • This counteracts the so-called edge weakness, this means that there is no inhibition by the Stabilizer takes place that would locally inhibit the deposition of nickel.
  • Another The advantage is that the stabilizer is not used up so quickly must be replenished. By adding the further complexing agent incredibly, does not affect the stability of the bathroom.
  • a salary in the range mentioned is advantageous, but is due to a higher concentration no deterioration in bathing properties can be seen.
  • the nickel content is preferably between 6 and 8 g per liter of bath liquid and the concentration of the reducing agent between 25 and 35 g per liter of bath liquid.
  • the stoichiometric ratio is in these concentration ranges particularly advantageous between the dissolved nickel and its reducing agent, so that there is a constant deposition rate over several MTOs
  • the concentration of the reducing agent is preferably 30 g per liter Bath liquid.
  • the carbon or hydroxycarboxylic acids preferably contain no more than 16 C atoms.
  • the alkyl groups present in the accelerator preferably do not contain contain more than 6, preferably not more than 4 carbon atoms or the aryl groups not more than 9, preferably not more than 6, carbon atoms.
  • a mixture of milk, apple and / or is advantageously used as the complexing agent Acetic acid is used, the molar ratio of which is preferably about 11: 4: 1 reads. This relationship has proven particularly beneficial in terms of complexation of ionic nickel.
  • the unfolds advantageously Effect of the complexing agent for a molar concentration between 0.6 and 0.8 Moles per liter. For the stabilizer is about 1 mg per liter Bath liquid cheap.
  • N-ethyl thiourea or benzyl isothiourea are preferred accelerators used These two substances are thermally stable, so that hardly any Decomposition takes place, which would necessitate subsequent dosing. By the low formation of sulfur gives you a very pure nickel layer few built-in foreign atoms, which leads to good corrosion resistance leads.
  • the pH of the bath should be 5.0 and is adjusted with ammonia solution.
  • the bath is operated and enabled at a temperature of 88-90 ° C a deposition rate of 15 to 21 ⁇ m per hour.
  • the new accelerator especially N-ethyl thiourea
  • the risk of pitting corrosion is reduced because the storage of Sulfur in the deposited nickel layer is reduced.
  • Particularly advantageous affects the good adhesion of gold on the nickel layer - due to a Phosphorus content less than 10% - on printed circuit boards. You also get with these small amounts of phosphorus in the nickel layer easily solderable and bondable Nickel / gold layers on the circuit board over the entire bath age of the Nickel baths.
  • a second embodiment differs from the first only in that 3 ml of methylglycine-diacetic acid is added to the nickel bath. This is achieved. that the stabilizer is partially complexed, which surprisingly the accumulation of lead, e.g. on a conductor edge, is reduced.

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemically Coating (AREA)
  • Catalysts (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Claims (14)

  1. Bain aqueux, acide de précipitation par réduction pour la précipitation sans courant de nickel, qui contient, dans 1 litre de liquide du bain, les quantités indiquées ci-après de substances dissoutes :
    de 3 à 10 g de nickel sous la forme d'un sel de nickel,
    de 5 à 45 g d'un hypophosphite à titre d'agent de réduction,
    de 0,4 à 1 mole d'un ou de plusieurs composés choisis parmi le groupe comprenant des acides carboxyliques et hydroxycarboxyliques, y compris leurs acides dicarboxyliques et tricarboxyliques, à titre de formateur de complexe pour le nickel,
    de 0,5 à 3 mg de l'acétate ou d'un sulfate de plomb, d'étain, d'arsenic, de thallium ou de molybdène, à titre de stabilisateur,
    à titre d'accélérateur, un dérivé de thiourée, d'isothiourée ou de rhodanide qui présente, à titre de substituants sur l'atome d'azote ou sur l'atome de soufre, des groupes alkyle et/ou des groupes aryle, en une concentration molaire de 1 à 3 fois supérieure à celle du stabilisateur, et
    auquel on ajoute un formateur de complexe qui complexe le stabilisateur de manière spécifique
  2. Bain selon la revendication 1, caractérisé en ce qu'on ajoute à titre de formateur de complexe pour le stabilisateur, de l'acide diacétique de méthylglycine.
  3. Bain selon l'une quelconque des revendications précédentes, caractérisé en ce que la teneur en nickel se situe entre 6 et 8 g par litre de liquide du bain.
  4. Bain selon l'une quelconque des revendications précédentes, caractérisé en ce que la concentration de l'agent de réduction se situe entre 25 et 35 g par litre de liquide du bain.
  5. Bain selon l'une quelconque des revendications précédentes, caractérisé en ce que la concentration de l'agent de réduction se situe à 30 g par litre de liquide du bain.
  6. Bain selon l'une quelconque des revendications précédentes, caractérisé en ce que les acides carboxyliques ou hydroxycarboxyliques ne contiennent pas plus de 16 atomes de carbone.
  7. Bain selon l'une quelconque des revendications précédentes, caractérisé en ce que le formateur de complexe pour le nickel contient de l'acide lactique, de l'acide malique et/ou de l'acide acétique.
  8. Bain selon l'une quelconque des revendications précédentes, caractérisé en ce que le formateur de complexe pour le nickel est constitué d'acide lactique, d'acide malique et d'acide acétique dans le rapport molaire d'environ 11:4:1.
  9. Bain selon l'une quelconque des revendications précédentes, caractérisé en ce que la concentration du formateur de complexe pour le nickel se situe entre 0,6 et 0,8 mole par litre de liquide du bain.
  10. Bain selon l'une quelconque des revendications précédentes, caractérisé en ce que la concentration du stabilisateur s'élève à environ 1 mg par litre de liquide du bain.
  11. Bain selon l'une quelconque des revendications précédentes, caractérisé en ce que la concentration du formateur de complexe complexant le stabilisateur se situe entre 0,5 et 5 ml par litre de liquide du bain.
  12. Bain selon l'une quelconque des revendications précédentes, caractérisé en ce que les groupes alkyle présents dans l'accélérateur ne contiennent pas plus de 6, de préférence plus de 4 atomes de carbone, respectivement les groupes aryle ne contiennent pas plus de 9, de préférence pas plus de 6 atomes de carbone.
  13. Bain selon l'une quelconque des revendications précédentes, caractérisé en ce que le dérivé de thiourée est une N-éthyl-thiourée.
  14. Bain selon l'une quelconque des revendications précédentes, caractérisé en ce que le dérivé d'isothiourée est une benzylisothiourée.
EP98114391A 1997-08-06 1998-07-31 Bain de nickel reducteur Expired - Lifetime EP0897998B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19733991A DE19733991A1 (de) 1997-08-06 1997-08-06 Reduktives Ni-Bad
DE19733991 1997-08-06

Publications (3)

Publication Number Publication Date
EP0897998A2 EP0897998A2 (fr) 1999-02-24
EP0897998A3 EP0897998A3 (fr) 1999-05-12
EP0897998B1 true EP0897998B1 (fr) 2001-12-05

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EP98114391A Expired - Lifetime EP0897998B1 (fr) 1997-08-06 1998-07-31 Bain de nickel reducteur

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EP (1) EP0897998B1 (fr)
AT (1) ATE210207T1 (fr)
DE (2) DE19733991A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7803457B2 (en) 2003-12-29 2010-09-28 General Electric Company Composite coatings for groundwall insulation, method of manufacture thereof and articles derived therefrom

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19908755A1 (de) * 1999-02-19 2000-08-24 Atotech Deutschland Gmbh Verfahren zum elektrolytischen Abscheiden einer Metallschicht auf elektrisch nichtleitenden Oberflächen
US7491445B2 (en) * 2004-09-02 2009-02-17 Sekisui Chemical Co., Ltd. Electroconductive fine particle and anisotropically electroconductive material comprising non-crystal and crystal nickel plating layers and method of making thereof
CN103422079B (zh) * 2012-05-22 2016-04-13 比亚迪股份有限公司 一种化学镀铜液及其制备方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3489576A (en) * 1966-08-04 1970-01-13 Gen Motors Corp Chemical nickel plating
US4483711A (en) * 1983-06-17 1984-11-20 Omi International Corporation Aqueous electroless nickel plating bath and process
US4983428A (en) * 1988-06-09 1991-01-08 United Technologies Corporation Ethylenethiourea wear resistant electroless nickel-boron coating compositions
KR960005765A (ko) * 1994-07-14 1996-02-23 모리시다 요이치 반도체 장치의 배선형성에 이용하는 무전해 도금욕 및 반도체 장치의 배선성형방법
TW390915B (en) * 1995-10-23 2000-05-21 Uyemura C & Co Ltd Electroless nickel plating solution and method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7803457B2 (en) 2003-12-29 2010-09-28 General Electric Company Composite coatings for groundwall insulation, method of manufacture thereof and articles derived therefrom

Also Published As

Publication number Publication date
DE19733991A1 (de) 1999-02-11
DE59802304D1 (de) 2002-01-17
ATE210207T1 (de) 2001-12-15
EP0897998A2 (fr) 1999-02-24
EP0897998A3 (fr) 1999-05-12

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