Method for depositing a palladium layer suitable for wire bonding on conductors of a printed circuit board and palladium bath for use in said method
A technology for printed circuit boards and palladium layers, applied in the field of depositing palladium layers suitable for bonding wires on printed circuit board conductors and the palladium bath used in the above, can solve problems such as inapplicable wire bonding
Inactive Publication Date: 2012-05-30
DODUCO GMBH CO DR EUGEN DURRWACHTER
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[0030] Suitable chemical (reduction) baths for depositing palladium are known. A very suitable bath has the following composition:
[0031]0.5-3 g / l palladium in the form of dissolved chloride, sulphate, acetate, phosphate or similar salts, or complexes incorporating palladium, such as chlorine complexes, amino complexes, nitrite complexes or similar complexes.
[0032] Reducing agent, sodium hypophosphite of 5-50 g / l or sodium formate of 1-50 g / l or formic acid of 1-50 g / l.
[0033] Inorganic complexing agents such as sodium citrate, malonate, succinate, potassium phosphate, potassium dihydrogen phosphate, ammonium sulfate.
[0034] organic complexing agents such as EDTA, EDTA derivatives, amines such as triethanolamine, tris-(2-aminoethyl)-amine, diethylenetriamine, triethylenetetramine, 1,3-diaminopropane, Each of these can be used alone or in combination.
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Abstract
The invention relates to a method for generating a surface that can be bonded with gold wire. Said surface is obtained by first depositing an exchange palladium layer made of the electrolyte according to the invention on conductors of printed circuit boards, in particular on conductors made of copper or conductive paste. Said exchange palladium layer is then reinforced with a palladium layer, deposited from a chemical palladium electrolyte. In order to protect the palladium, an exchange gold layer is then applied. According to the invention, an exchange palladium bath is used, comprising an organic brightener.
Description
technical field [0001] The invention relates to a method having the features stated in the preamble of claim 1 . Such a method is known from WO 2006 / 074902 A2. Background technique [0002] According to known methods, firstly, nickel is deposited from an electroless nickel bath by chemical reduction (ie without application of external current) on a conductor made of copper, which is located on an organic or ceramic printed circuit board. It is also possible to deposit a nickel alloy instead of nickel from the corresponding nickel alloy bath without applying an external current. Then a thin palladium layer of 10 nm-40 nm thickness is deposited on the nickel or nickel alloy layer by charge exchange from the palladium exchange bath. Palladium exchange baths generally consist of inorganic or organic acids and palladium salts of said acids and inorganic compounds of at least one element, copper, thallium, selenium and tellurium, preferably copper sulfate. The pH value of the ...
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IPC IPC(8): C23C18/54
CPCH01L2924/0002C23C18/42H01L2224/45124H01L2224/85464H01L24/45C23C18/54H01L2224/48227H01L2224/45144H01L2224/48664H01L2224/48764H01L2924/12044H01L2924/00014H01L2924/00
Inventor J·艾伯E·马卡W·马舒特S·奥尔舒兰格
Owner DODUCO GMBH CO DR EUGEN DURRWACHTER