Plating bath composition and method for electroless plating of palladium

Patent metadata

Field	Value
Publication number	US-2018340260-A1
Application number	US-201615778242-A
Country	US
Kind code	A1
Filing date	Nov 28, 2016
Priority date	Nov 27, 2015
Publication date	Nov 29, 2018
Grant date	—

Abstract

The invention relates to an aqueous plating bath composition and a method for depositing a palladium layer by electroless plating onto a substrate. The aqueous plating bath composition according to the invention comprises a source for palladium ions, a reducing agent for palladium ions and an unsaturated compound. The aqueous plating bath composition according to the invention has an improved stability against undesired decomposition due to the unsaturated compounds while keeping the deposition rate for palladium at the desired satisfying value. The aqueous plating bath composition has also a prolonged life time. The unsaturated compounds of the invention allow for adjusting the deposition rate to a satisfying range over the bath life time and for electrolessly depositing palladium layers at lower temperatures.

First claim

1 . An aqueous plating bath composition for electroless deposition of palladium, comprising
(i) at least one source for palladium ions, (ii) at least one reducing agent for palladium ions, and (iii) at least one unsaturated compound selected from compounds according to Formulae (I) and (II), salts thereof, and mixtures of the aforementioned

wherein R1, R3, R5 are selected independently of each other from the group consisting of —H; unsubstituted or substituted, linear C1 to C20 alkyl group; unsubstituted or substituted, branched C3 to C20 alkyl group; and unsubstituted or substituted aryl groups; and
wherein R2, R4 are selected independently of each other from the group consisting of —H; unsubstituted or substituted, linear C1 to C20 alkyl group; unsubstituted or substituted, branched C3 to C20 alkyl group; unsubstituted or substituted aryl groups; and —(CH(R10)) n -X—(C(R8)(R9)) m -R7; and wherein R2 is not —H if R4 is —H or R4 is not —H if R2 is —H; and
wherein R6 is selected from the group consisting of unsubstituted or substituted, linear C1 to C20 alkyl group; unsubstituted or substituted, branched C3 to C20 alkyl group; unsubstituted or substituted aryl groups; and —(CH(R10)) n -X—(C(R8)(R9)) m -R7; and
wherein X is selected from the group consisting of O, NH, and NCH 3 ; R7 is selected from the group consisting of hydroxyl, amino, sulfonic acid, carboxyl; R8, R9, R10 are selected independently of each other from the group consisting of hydrogen and C1 to C4 alkyl group; n is an integer ranging from 1 to 6; and m is an integer ranging from 1 to 8, and
wherein substituents of the substituted, linear C1 to C20 alkyl group; the substituted, branched C3 to C20 alkyl group; or the substituted aryl groups are selected independently of each other from the group consisting of hydroxyl, aldehyde, sulfonic acid, mercapto, methoxy, ethoxy, halogen, allyl, vinyl, phenyl, pyridyl and naphthyl groups,
wherein the amino group according to R7 is selected from —NH(R11), —N(R11)(R12), —N + (R11)(R12)(R13), wherein R11, R12, R13 are selected independently of each other from methyl, ethyl, n-propyl and iso-propyl, and
wherein the aqueous plating bath composition further comprises at least one complexing agent for palladium ions selected from the group consisting of primary amines, secondary amines and tertiary amines.

2 . The aqueous plating bath composition according to claim 1 wherein R1, R3, R5 are selected independently of each other from the group consisting of —H; unsubstituted or substituted, linear C1 to C10 alkyl group; unsubstituted or substituted, branched C3 to C10 alkyl group; and unsubstituted or substituted aryl groups; and
wherein R2, R4 are selected independently of each other from the group consisting of —H; unsubstituted or substituted, linear C1 to C10 alkyl group; unsubstituted or substituted, branched C3 to C10 alkyl group; unsubstituted or substituted aryl groups; and —(CH(R10)) n -X—(C(R8)(R9)) m -R7; and wherein R2 is not —H if R4 is —H or R4 is not —H if R2 is —H; and
wherein R6 is selected from the group consisting of unsubstituted or substituted, linear C1 to C10 alkyl group; unsubstituted or substituted, branched C3 to C10 alkyl group; unsubstituted or substituted aryl groups; and —(CH(R10)) n -X—(C(R8)(R9)) m -R7; and
wherein X is selected from the group consisting of O and NH; R8, R9, R10 are selected independently of each other from the group consisting of hydrogen, methyl and ethyl group; n is an integer ranging from 1 to 4; and m is an integer ranging from 1 to 6.

3 . The aqueous plating bath composition according to claim 1 wherein the unsubstituted or substituted aryl groups according to R1, R2, R3, R4, R5, R6 are selected independently of each other from the group consisting of phenyl, pyridyl and naphthyl.

4 . The aqueous plating bath composition according to claim 1 wherein the at least one unsaturated compound according to Formulae (I) and/or (II) is selected from the group comprising prop-2-en-1-ol, 3-methylbut-3-en-1-ol, prop-2-yn-1-ol, 3-(prop-2-yn-1-yloxy)propane-1-sulfonic acid, 3-(prop-2-yn-1-ylamino)-propane-1-sulfonic acid, 4-(prop-2-yn-1-yloxy)butane-1-sulfonic acid, 4-(but-3-yn-1-yloxy)butane-1-sulfonic acid, 2-(pyridine-3-yl)but-3-yn-2-ol, 2-(prop-2-yn-1-yloxy)ethan-1-ol, 2-(prop-2-yn-1-yloxy)-acetic acid, and 2-(prop-2-yn-1-yloxy)propanoic acid.

5 . The aqueous plating bath composition according to claim 1 , wherein the at least one unsaturated compound according to Formulae (I) or (II) has a concentration ranging from 0.01 to 500 mg/l.

6 . The aqueous plating bath composition according to claim 1 , wherein the pH-value ranges from 4 to 7.

7 . (canceled)

8 . The aqueous plating bath composition according to claim 1 , wherein the mole ratio of the complexing agent for palladium ions and palladium ions in the electroless plating bath ranges from 0.5:1 to 50:1.

9 . The aqueous plating bath composition according to claim 1 , wherein the at least one reducing agent for palladium ions is selected from the group comprising hypophosphorous acid, amine boranes, borohydrides, hydrazine, formaldehyde, formic acid, derivatives of the aforementioned and salts thereof.

10 . The aqueous plating bath composition according to claim 1 , wherein the concentration of the at least one reducing agent ranges from 10 to 1000 mmol/l.

11 . A method for electroless palladium plating comprising the steps of
a) providing a substrate, b) contacting the substrate with the aqueous plating bath composition according to claim 1 and thereby depositing a layer of palladium onto at least a portion of the substrate.

12 . The method for electroless palladium plating according to claim 11 wherein the substrate is contacted with the aqueous plating bath composition at a temperature of 30 to 65° C. in step b).

13 . A method for adjusting the deposition rate to a satisfying range over the life time of any aqueous electroless palladium deposition bath, the method comprises the steps of
c) providing any aqueous electroless palladium deposition bath, and d) adding at least one unsaturated compound according to Formulae (I) and/or (II) as defined in claim 1 to the electroless palladium deposition bath, e) and thereby decreasing the deposition rate of the aqueous electroless palladium deposition bath.

14 . The method for adjusting the deposition rate according to claim 13 further comprising one or more of steps
c.i) determining the deposition rate and/or the concentration of the at least one unsaturated compound according to Formulae (I) and (II) within the aqueous electroless palladium deposition bath according to step c);
c.ii) comparing the value for deposition rate and/or concentration of the at least one unsaturated compound according to Formulae (I) and (II) determined according to step c.i) with pre-set corresponding threshold values;
c.iii) determining the deviation of the value for deposition rate and/or concentration of the at least one unsaturated compound according to Formulae (I) and (II) from their corresponding threshold values;
c.iv) correlating the deviation determined according to step c.iii) to an amount of the at least one unsaturated compound according to Formulae (I) and (II) to be added to the aqueous electroless palladium deposition bath in step d).

15 . (canceled)

16 . The aqueous plating bath composition according to claim 2 wherein the unsubstituted or substituted aryl groups accord

Assignees

• Atotech Deutschland Gmbh

Inventors

• Walter Andreas
• Suchentrunk Christof
• Beck Thomas
• Steinberger Gerhard
• Bera Holger
• Brunner Heiko
• Froese Bernd

Classifications

• H10P14/46

  using a liquid · CPC title

• C23C18/32

  Coating with nickel, cobalt or mixtures thereof with phosphorus or boron (C23C18/50 takes precedence) · CPC title

• H05K3/187

  means therefor, e.g. baths, apparatus · CPC title

• C23C18/1651

  Two or more layers only obtained by electroless plating · CPC title

• C23C18/44 Primary

  using reducing agents · CPC title