EP0044878B1 - Stabiles wässriges Kolloid zur Aktivierung nichtleitender Substrate und Verfahren zur Aktivierung - Google Patents

Stabiles wässriges Kolloid zur Aktivierung nichtleitender Substrate und Verfahren zur Aktivierung Download PDF

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Publication number
EP0044878B1
EP0044878B1 EP19800104428 EP80104428A EP0044878B1 EP 0044878 B1 EP0044878 B1 EP 0044878B1 EP 19800104428 EP19800104428 EP 19800104428 EP 80104428 A EP80104428 A EP 80104428A EP 0044878 B1 EP0044878 B1 EP 0044878B1
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EP
European Patent Office
Prior art keywords
colloid
particles
zeta potential
copper
activating
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
Application number
EP19800104428
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English (en)
French (fr)
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EP0044878A1 (de
Inventor
William Robert Brasch
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.)
Shipley Co Inc
Original Assignee
LeaRonal Inc
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 LeaRonal Inc filed Critical LeaRonal Inc
Priority to DE8080104428T priority Critical patent/DE3068305D1/de
Priority to EP19800104428 priority patent/EP0044878B1/de
Publication of EP0044878A1 publication Critical patent/EP0044878A1/de
Application granted granted Critical
Publication of EP0044878B1 publication Critical patent/EP0044878B1/de
Expired 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
    • C23C18/18—Pretreatment of the material to be coated
    • C23C18/20—Pretreatment of the material to be coated of organic surfaces, e.g. resins
    • C23C18/28—Sensitising or activating

Definitions

  • This invention relates to a stable aqueous colloid for the activation of non-conductive substrates and the method of activating. Namely the invention relates to a novel copper colloid for the activation of non-conductive materials, particularly plastics, to prepare such materials for subsequent metal coating by conventional electroless and electroplating.
  • the process requires the activating of the non-conductive substrate since electroless or electroplating cannot be carried out on such a substrate.
  • the activating is followed by an electroless plating which will carry a current for subsequent electroplating.
  • the noble metal of the activating solution serves to activate, catalyze, or seed the non-conductive substrate for the subsequent electroless plating bath. After a few minutes in the electroless metal plating bath, the article will have a very thin coating of the selected metal of the bath thereon. It is then rinsed and the article-may then be further plated with the same or another metal by well known electroplating processes.
  • the U.S. Patent No. 3,011,920 to Shipley discloses the use of colloidal dispersions of various metals in combination with reducing agents to achieve activation of insulative substrates for subsequent electroless plating.
  • the working examples utilize noble metals or hydrous oxides thereof as the colloidal particles and stannous chloride or tannic acid as a reducing agent.
  • the specification in column 2 refers to the fact that other metals, including numerous non-noble metals, may similarly be employed to catalyze non-conductive substrates for electroless deposition.
  • U.S. Patents Nos. 3,993,799 and 4,136,216 issued to Feldstein also disclose the use of non-noble hydrous oxide or metallic colloids for treating non-conductive plastics followed by reduction of the hydrous oxide coating on the plastic to achieve at least a degree of activation for subsequent electroless plating.
  • US - A - 4,020,197 discloses a method for catalytic sensitization and metallization for subsequent electroless metal deposition, using a copper (I) ion compound bath solution. In this case the bath solution represents an ionic solution, while according to the invention a stable aqueous colloid is used.
  • AU - B - 422,372 describes improvements in metallizing flexible substrates, using printing inks together with a resin carrier.
  • U.S. Patent No. 3,958,048 to Donovan discloses a process for the surface activation of non-conductive substrates for electroless plating by treating the surface of the substrate with an aqueous composition containing catalytically active water insoluble particles formed by a reaction of a non-noble metal and a water soluble hydride in the presence of a water soluble organic suspending agent.
  • the suspension is required to have a pH below 5 or from 7.7 to 9.5.
  • Copper salts are disclosed as one of the non-noble metals, dimethylamine borane (DMAB) as one of the hydrides, and gelatin as one of the many possible organic suspending agents.
  • DMAB dimethylamine borane
  • compositions made in accordance with the Donovan disclosure are not sufficiently stable for practicable or commercial use. It has been found, for instance, that the compositions of the examples break down during a period varying from a few hours to a few days rendering the suspensions commercially impractical.
  • This invention relates to a novel stable copper colloid having a particle size between about 10 and 100 millimicrons (mm), a particle zeta potential between about +3 and +13 millivolts (mv) and containing a sufficient number of particles to activate a non-conductive substrate that it can accept an electroless deposition.
  • the colloids of this invention are also stable and capable of activating a non-conductive substrate over practically the entire pH range, and advantageously between a pH of about 2 through 8. The ability to use these colloids over a wide pH range lends more versatility to the colloids and permits continued operation under commercial conditions where pH changes occur during operation.
  • the colloids of this invention can be made by using a stabilizer or suspending agent which will produce or impart to the metallic and/or oxide copper particles of the colloid a zeta potential of between about +3 and +13 mv, advantageously between about +4 and +10 mv.
  • the suspending agent should have a zeta potential which, when combined with the colloidal copper particles, will produce particles having a zeta potential between about +3 and +13 mv. If the copper particles have a negative zeta potential, it may be necessary to use a suspending agent having a high positive zeta potential such as +18 mv to impart the desired zeta potential to the particles of the colloids.
  • the use of certain types of gelatin are examples of suspending agents that can be used to produce colloids having the desired zeta potential. Typically an acid washed Type A gelatin of sufficient purity can be used.
  • the type of gelatin, the manner in which it was produced or purified, and its purity also play a role in the ability of the gelatin to impart the desired zeta potential to the colloidal copper particles.
  • the suspending agent or gelatin should be sufficiently free of interfering ions, such as excess sodium ions, which will interfere with imparting the desired zeta potential to the particles of the colloid.
  • Other suspending agents could be used in place of gelatin so long as they possess the desired zeta potential, or are capable of imparting to the particles of the colloid a zeta potential between about +3 and +13 mv, and do not highly disassociate and migrate from the copper particles.
  • a person skilled in the art can measure zeta potentials and select the correct suspending agent to produce a colloid with part- ides having the desired zeta potential when given the teachings of this application.
  • non-noble colloids can be prepared in many ways, but they all suffer various deficiencies which prohibits their commercial use.
  • the colloids particularly on copper clad circuit boards, must have the properties of stability, particle size and zeta potential.
  • Colloidal particles must deposit on a non-conductive surface in a sufficient amount and of sufficient uniformity so that subsequent electroless plating will produce a deposit of sufficient uniformity to permit subsequent electroplating.
  • the colloidal particles must also adhere to the surface to prevent peel-off after electroless and electroplating during fabrication and use of the end product. In other words the colloid cannot spot deposit on the substrate.
  • Non-uniform or spotty deposits can be caused by different factors, such as an insufficient number of particles in the colloid, a colloid which is too stable, agglomerated colloidal particles, due to the instability of the colloid, too many of the particles are too small, etc.
  • a colloid having particles of a zeta potential of less than about +2 mv are not stable and do not adequately adhere to or activate non-conductive surfaces, such as glass.
  • the particles of applicant's colloids not only have a low positive zeta potential but a small particle size which renders them uniquely suitable for activating plastics and the plastic portions of circuit boards, particularly where the plastic contains a glass filler.
  • Donovan patent No. 3,958,048 The prior art believed to be the closest and known to the applicant is the Donovan patent No. 3,958,048.
  • Donovan does mention gelatin, there is no recognitiaon of its significance in producing stable colloids which can be used to activate a non-conductive substrate at a pH above 5 and below 7.7.
  • Donovan teaches the colloids made according to his invention are inoperable within the pH range.
  • the broad term "gelatin” does not disclose or teach applicant's specific stabilizers having a specific zeta potential capable of imparting the desired zeta potential to the particles of the colloid.
  • examples 1 and 2 of the Donovan patent 3,958,048 varied the pH.
  • cupric gluconate and cupric acetate were used respectively as metal salts.
  • dispersing agent a sodium salt of polymerized alkyl naphthalene sulfonic acids (Daxad 11) was utilized.
  • the final suspension for the activation of non-conductive substrates for electroless plating according to the above-identified US-PS also contained sodium borohydride, and in case of example 2 a further dispersing agent, dextrine, was used. Immersion time was 4 minutes at a temperature of 36,7°C (example 1) or 54,4°C (example 2).
  • a degreased plaque was immersed 6 to 7 minutes into an etch solution at a temperature of about 65,6°C. Following a water rinse, the plaques were then immersed in the suspensions described for a period of 4 minutes. The plaques were then water rinsed and immersed in an electroless copper plating solution.
  • the particles had a zeta potential of about -20 at a pH of 6, but the velocity of the particles varied during the test, that is, some particles were much slower than the average.
  • the particles had a zeta potential of about -25.
  • Example 2 With respect to Example 2, at a pH of 2 the particles had a zeta potential of about +1, and at a pH of 4 a zeta potential of about -1. At a pH of 6, the zeta potential was about -2.
  • the colloid had a zeta potential of about +9 mv at a pH of 4, and a zeta potential of +13 mv at a pH of 2.
  • the particles had a zeta potential of about +3 mv at a pH of 6 and a zeta potential of +4 mv at a pH of 2.
  • the particles had a zeta potential of +7 mv and when dextrin was eliminated and only the gelatin used, the particles had a zeta potential of +13 mv.
  • the copper colloids are unique and novel and are particularly advantageous for the activation of copper clad circuit boards employing glass filled plastics.
  • there are at least three different materials to be dealt with namely the copper clad, the plastic, and the glass filler.
  • the activating colloid must adequately adhere to all three of these materials or the subsequent electroless and electroplate will peel off during subsequent fabrication or use.
  • an aqueous stripping solution such as neutral hydrazine hydrate
  • the activation of such circuit boards can be accomplished by using applicant's novel colloids which have a particle size of between about 10 and 100 millimicrons and a particle zeta potential of between about +3 and +13, preferably between about 4 and 10.
  • colloids of this invention resides in the fact that the particles are not only small but also have a low positive zeta potential.
  • the colloids are also stable, that is, the particle size does not appear to grow causing the particle to precipitate out leaving a few particles to effect activation or to cause alteration of the zeta potential to a degree that the particles will not adhere sufficently to the substrate.
  • This stability of applicant's colloid is advantageously maintained over a wide pH range. Stability over a narrow pH range would not be practicable in commercial production since the pH would necessarily be altered during operation.

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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)

Claims (6)

1. Stabiles wässriges Kolloid zur Aktivierung nicht-leitender Substrate zur stromlosen Plattierung, dadurch gekennzeichnet, dass dieses metallische Kupfer- und/oder Kupferoxidteilchen mit einer Teilchengrösse von zwischen ca. 10 und 100 Millimikron und einem Zeta-Potential zwischen ca. +3 und +13 Millivolt umfasst, wobei das Kolloid eine ausreichende Menge an Teilchen enthält, um die Oberfläche eines Nichtleiters zu aktivieren.
2. Kolloid gemäss Anspruch 1, dadurch gekennzeichnet, dass das Kolloid einen pH von ca. 7 aufweist.
3. Kolloid gemäss Anspruch 1, dadurch gekennzeichnet, dass das Kolloid einen pH zwischen ca. 4 und 8 aufweist.
4. Kolloid gemäss Anspruch 1, dadurch gekennzeichnet, dass das Kolloid einen pH zwischen ca. 2 und 8 aufweist.
5. Verfahren zur Aktivierung eines nichtleitenden Substrates zur stromlosen Metallabscheidung mit Hilfe eines Kolloids, welches metallische Kupfer-und/oder Kupferoxidteilchen enthält, dadurch gekennzeichnet, dass die Metall- oder Oxidteilchen mit einem Suspensionsmittel behandelt werden, welches ein ausreichendes Zeta-Potential aufweist, um den Metall- oder Kupferoxidteilchen ein Zeta-Potential zwischen ca. +3 und + 13 Millivolt zu verleihen.
6. Verfahren gemäss Anspruch 5, dadurch gekennzeichnet, dass die Kupfer- und/oder Kupferoxidteilchen nach der Behandlung mit dem Suspensionsmittel eine Teilchengrösse zwischen ca. 10 und 100 Millimikron aufweisen.
EP19800104428 1980-07-28 1980-07-28 Stabiles wässriges Kolloid zur Aktivierung nichtleitender Substrate und Verfahren zur Aktivierung Expired EP0044878B1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE8080104428T DE3068305D1 (en) 1980-07-28 1980-07-28 A stable aqueous colloid for the activation of non-conductive substrates and the method of activating
EP19800104428 EP0044878B1 (de) 1980-07-28 1980-07-28 Stabiles wässriges Kolloid zur Aktivierung nichtleitender Substrate und Verfahren zur Aktivierung

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19800104428 EP0044878B1 (de) 1980-07-28 1980-07-28 Stabiles wässriges Kolloid zur Aktivierung nichtleitender Substrate und Verfahren zur Aktivierung

Publications (2)

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EP0044878A1 EP0044878A1 (de) 1982-02-03
EP0044878B1 true EP0044878B1 (de) 1984-06-20

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EP19800104428 Expired EP0044878B1 (de) 1980-07-28 1980-07-28 Stabiles wässriges Kolloid zur Aktivierung nichtleitender Substrate und Verfahren zur Aktivierung

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Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4520046A (en) * 1983-06-30 1985-05-28 Learonal, Inc. Metal plating on plastics
US4719145A (en) * 1983-09-28 1988-01-12 Rohm And Haas Company Catalytic process and systems
US4759952A (en) * 1984-01-26 1988-07-26 Learonal, Inc. Process for printed circuit board manufacture
US4761304A (en) * 1984-01-26 1988-08-02 Learonal, Inc. Process for printed circuit board manufacture
US4847114A (en) * 1984-01-26 1989-07-11 Learonal, Inc. Preparation of printed circuit boards by selective metallization
DE3417563C2 (de) * 1984-05-11 1986-12-04 Dr.-Ing. Max Schlötter GmbH & Co KG, 7340 Geislingen Verfahren zur Herstellung von Metallmustern auf isolierenden Trägern, insbesondere gedruckte Schaltungen
JP4262190B2 (ja) * 2003-12-26 2009-05-13 キヤノン株式会社 抵抗膜の成膜方法及び該成膜方法を用いて形成された画像表示装置とテレビジョン装置
JP4561558B2 (ja) * 2005-09-22 2010-10-13 巌 菱田 銅イオン発生組成物を含む粒状組成物およびそれを用いて水中の有害菌や雑菌の増殖を抑制する方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU422372B1 (en) * 1966-03-16 1972-03-14 Improvements in metallizing flexible substrata
DE2409251C3 (de) * 1974-02-22 1979-03-15 Kollmorgen Corp., Hartford, Conn. (V.St.A.) Verfahren zum katalytischen Bekeimen nichtmetallischer Oberflächen für eine nachfolgende, stromlose Metallisierung und Badlösungen zur Durchführung des Verfahrens

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Publication number Publication date
EP0044878A1 (de) 1982-02-03
DE3068305D1 (en) 1984-07-26

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