Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/50—Electroplating: Baths therefor from solutions of platinum group metals
  • C25D3/52—Electroplating: Baths therefor from solutions of platinum group metals characterised by the organic bath constituents used
• • 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
  • H05K3/244—Finish plating of conductors, especially of copper conductors, e.g. for pads or lands

Definitions

• Electrolysis or electrodeposition is carried out with an aqueous neutral or alkaline bath containing a palladium compound and an ammonium salt of a weak organic acid which does not form an insoluble compound with the palladium compound.
• This invention relates to improvements in and relating to the electrodeposition of palladium onto a basis metal.
• Palladium is usually deposited from a plating bath or electrolyte which comprises an aqueous solution of a palladium compound and generally also contains ammonia to render the bath slightly alkaline.
• palladium plating baths based on palladium diammino-dinitrite Pd(NH (NO commonly known as the P salt or palladium tetrammino-dinitrate, Pd(NH (NO have been proposed.
• Such baths are usually operated at a pH of from -5 to 9 and a temperature of from about 50 C. to 95 C.
• a palladium plating bath particularly suitable for plating printed circuit boards, which comprises an aqueous solution containing in addition to palladium ions, and ammonium ions, also a source of sulphamate ions, for example, the bath may be based on the reaction of the known P salt, above referred to, with sulphamic acid or ammonium sulphamate, to form a compound the exact nature of which is not yet definitely known.
• the bath is stated to offer advantages over the conventional baths and to be operable at, or near, room temperature.
• the object of this invention is to provide a novel palladium plating bath or electrolyte which is stable, can be operated at a low temperature and by means of which substantially pore-free and heavy deposits of palladium can be consistently obtained.
• a plating bath or electrolyte for the electrodeposition of palladium comprises an aqueous neutral or alkaline solution containing a palladium compound and an ammonium salt of a weak organic acid, which does not form an insoluble compound with the palladium compound.
• a method of electrodepositing palladium comprises electrolysing an electrolyte comprising an aqueous neutral or alkaline solution containing a palladium compound and an ammonium salt of a weak organic acid which does not form an insoluble compound with the palladium compound.
• a method of electrodepositing palladium on a basis metal comprises depositing on said basis metal palladium metal from a plating bath or electrolyte comprising an aqueous neutral or alkaline solution containing a palladium compound and an ammonium salt of a weak organic acid which does not form an insoluble compound with the palladium compound.
• the palladium compound employed in carrying out the invention is preferably palladium-diammino-dinitrite.
• palladium compounds such as palladium-tetrammino-nitrate, Pd(NH (NO or palladium chloride may also be used.
• the organic acid salts may advantageously be chosen from the following ammonium salts, namely, ammonium tartrate, ammonium oxalate, ammonium citrate, ammonium formate and an ammonium salt of ethylene diamine tetra-acetic acid. Of these salts, the applicants have found that very satisfactory results are obtained with the use of ammonium formate.
• Ammonia is preferably included in the solution to give a pH of from 7 to 10, preferably 8-9, the brightness of the deposit in general increasing with increase in the pH.
• the solution should, preferably, be free of cyanide ions.
• the baths of the invention should preferably be operated at a temperature of 15-75 C. It will be found advisable, however, in the case of a bath containing ammonium formate, not to operate at :a temperature of over 40 C. over a period as, in that event, the palladium is liable to precipitate out and be deposited chemically.
• the current density at which the baths are operated may vary from 1 amp/sq. ft. to 500 amps/ sq. ft.
• the plating bath is made by dissolving the palladium salt in ammonia at the rate of 2 mls. of 0.880 ammonia per gram of palladium (2.175 grams of Pd(NH (NO correspond to 1 gram of Pd), and. an equal amount of water. The organic acid salt is then added and the pH adjusted as required.
• This bath should be operated at a current density of 6 amps/sq. ft. at a temperature of 30 C.
• the pH of the bath was adjusted to 8.5. A bright deposit of palladium was obtained.
• Ammonium oxalate -50 g./l. Water to 1 litre.
• This bath should also be operated at a current density of 6 amps/sq. ft. at a temperature of 30 C.
• the pH of 3 the bath was adjusted to 8.5. A bright deposit of palladium was obtained.
• the ethylene diamine tetra-acetic acid vilas g fi i The palladium diammino-chloride was dissolved in amwith ammonia to form the ammonium sat an t e pa ladium salt dissolved in ammonia.
• bath d H gave a u deposlt of a th1ckness of 0.00017
• the bath Should be operated at Cuarrent denslty of 6 inch when operated at a current density of 6 amps/sq. amps/Sq at a temperature of cathode ft. and a temperature of 30 C
• the cathode efficiency efficiency is 59% and a bright deposit of a thickness of of the bath was 86% 0.00012 inch is obtainable.
• EXAMPLE XI EXAMPLE VI Palladium tetrammlno nitrate Pd(NH (NO 27.8 Palladium d1amrmno-d1n1tr1te Pd(NH (NO 24 g./l. AII11110Ili11II1PXa1at?/5O Ethylene diamine tetraacetic acid40.0 g./l. Water to 1 litre. a Water to 1 litre.
• the P of this bath was adjusted by addition of The ethylene diamine tetraacetic acid was neutralised mom-a to a Value of with ammonia and the pH of the final solution was ad- A bright deposit of a th1ckness of 0.0001 inch 1s objusted to 75 with dilute nitric acid tainable With this bath when operated at a current density This bath gave a dull deposit of a thickness of 000019 of 12 p q a temPerature of 9 fcathode inch when operated at a current density of 6 amps/ sq. ft. efficiency of 53% being obtained.
• the article being plated and a temperature of The cathode efficiency was should be agitated. 94%
• a method of electrodepositing palladium on a basis metal which comprises electrodepositing the palladium Example No XXII XXIII XXIV XXV XXVI XXVII Salt Grams per litre of salt 80 60 60 80 80 80 Grams per litre of palladium 14 15 10 10 16 as Pd(NHa)2(NO2)2. pH 8. 5 9. 0 8. 0 8. 6 8. 8 8. 5 Current density in amps/ftk- 30 6 30 6 3 12 Thickness in inches 0001 0.0001 0. 00015 0. 0001 0. 00012 0.
• Plating baths in accordance with this invention may be used to electrodeposit palladium onto copper, Phosphorbronze, brass, beryllium-copper, stainless steel, mild steel, nickel or silver or other metals. No particular pre-treatment is necessary, normal cleaning procedures being used.
• the invention is intended to include within its scope a method of electrodepositing palladium upon a base which comprises immersing the base as a cathode in a plating bath or electrolyte in accordance with the invention and electrolysing the said bath.
• the invention also includes within its scope any base when plated with palladium by the use of a plating bath or electrolyte in accordance with the invention or by the method of the invention.
• a plating bath or electrolyte for the electrodeposition of palladium consisting essentially of water, a palladium compound and an ammonium salt of a weak organic carboXylic acid, the bath containing substantially no ethylene diamine tetraacetic acid and having a pH of between about 7 and about 10.
• the bath or electrolyte claimed in claim 1 wherein the palladium compound is Pd(NH (NO 3.
• the bath or electrolyte claimed in claim 1 wherein the ammonium salt is ammonium tartrate, ammonium oxalate, ammonium citrate or ammonium formate.
• a method of electrodepositing palladium which comprises electrolyzing a bath or electrolyte consisting essentially of water, a palladium compound and an ammonium salt of a weak organic carboxylic acid, the bath containing substantially no ethylene diamine tetraacetic acid and having a pH between about 7 and about 10.
• a bath consisting essentially of water, a palladium compound and an ammonium salt of a weak organic carboxylic acid, said bath containing substantially no ethylene diamine tetraacetic acid and having a pH between about 7 and about 10.
• ammonium salt is ammonium tartrate, ammonium oxalate, ammonium citrate or ammonium formate.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electroplating And Plating Baths Therefor (AREA)
• Chemically Coating (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10212010

Family Applications (1)

Country Status (4)

Cited By (8)

Families Citing this family (1)

Citations (16)

• 1964
  • 1964-06-12 GB GB24457/64A patent/GB1035850A/en not_active Expired
• 1965
  • 1965-06-08 US US462433A patent/US3530050A/en not_active Expired - Lifetime
  • 1965-06-09 DE DEJ28310A patent/DE1239159B/de active Pending
  • 1965-06-09 FR FR20109A patent/FR1436451A/fr not_active Expired

Patent Citations (16)

Also Published As

Similar Documents