JPH04365877A - Catalyst liquid for copper base material-selecting electroless plating - Google Patents

Abstract

PURPOSE:To selectively form a good plating film only on a copper conductive part by using a catalytic liquid comprising a combination of paradium compd. and specified chelating agent. CONSTITUTION:The catalytic liquid is prepared by mixing a paradium compd. dissolved in hydrochloric acid or sulfuric acid with aq. soln. of chelating agent. To control pH, acid such as hydrochloric acid or an alkali compd. such as NaOH is used. As necessary, a surfactant thiourea of pH buffer can be used individually or by mixing thereof. The treatment with this catalytic liquid is performed as usual, by dipping the material in the liquid at about 10-90 deg.C for 10sec. to 10min.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst solution for selective electroless plating of copper-based materials.

0002

[Prior art and its problems] When electroless plating of Ni, Pd, Pd-Ni, etc. using a hypophosphorous acid compound as a reducing agent is applied to a copper-based material, it is usually used for reduction and deposition of the plating film. After applying a Pd compound onto the material as a catalyst, electroless plating is performed. In such a case, catalyst application methods include two-stage treatment using a SnCl2 solution and a PdCl2 solution, and treatment using a hydrochloric acid acidic aqueous solution of a PdCl2/SnCl2 mixed system. However, when these treatment methods are applied to an integrated insulator and conductor such as a printed circuit board, ceramic substrate, or chip component, all of the insulating and conductor parts are catalytically activated. Therefore, plating is performed on the entire surface in an electroless plating process, and it is not possible to form a plating film only on the conductor portion. There is also a known method of catalytically activating a copper-based material using an acidic solution of PdCl2 in hydrochloric acid, but in this case too, a portion of the catalyst component is adsorbed onto the insulator, resulting in the insulator being deposited during the plating process. Particularly when a plating film is formed and the spacing between the conductors is narrow, there is a problem in that a bridging phenomenon (plating bridge) occurs in which the conductors are partially coupled.

[0003] As a countermeasure to this problem, attempts have been made to increase the pH to weaken the catalytic activity, but even if the pH is raised to about 5, the plating bridge cannot be eliminated;
If this is the case, a colloidal precipitate will form, making it difficult to handle in practice.

[0004] In addition, efforts have been made to reduce the concentration of PdCl2 to weaken the catalytic activity, but in this case, the plating bridge disappears, but on the other hand, the catalytic activity becomes too weak and some plating does not adhere. There is a problem in that it causes a phenomenon (skip phenomenon).

[0005]

[Means for Solving the Problems] In view of the current state of the prior art as described above, the present inventor has proposed an electroless method that can selectively activate only copper-based materials and does not cause skip or bridge phenomena. We have been conducting extensive research to find a catalyst for plating. As a result, they found that the above object could be achieved by a catalyst liquid containing a combination of a palladium compound and a specific chelating agent.

That is, the present invention provides (I) a palladium compound of 0.0001 to 0.5 mol/l;
, and (II) (a) general formula

[0007]

[Chemical formula 8]

(wherein, X1, X2 and X3 are each the same or different, -CH2CO2M, -CH2PO3MM,
-CH(CH3)CO2M or -CH2CH2CO2M
and X4 is -CH2CO2M, -CH2PO3MM
, -CH2CH2OH, -CH(CH3)CO2M or -CH2CH2CO2M, X5 is H, -CH2C
O2M, -CH2PO3MM, -CH(CH3)CO2
M or -CH2CH2CO2M. In the above,
M is the same or different and each is H, K, Na or NH4
and n is an integer of 0 to 2), (b) General formula

[0009]

[Chemical formula 9]

(wherein, X6 and X7 are the same or different and each represents H, C1-5 alkyl, aralkyl, aralkenyl, aryl, -CH2CO2M, -CH(CH3)
CO2M, -CH2CH2CO2M, -CH2PO3M
M or -CH2CH2OH, X8 is H, C1-
5 alkyl, aralkyl, aryl, -CH2CO2M
, -CH(CH3)CO2M, -CH2CH2CO2M
, -CH2PO3MM, -CH2CH2OH, -(CH
2) Indicates p-NH2 or -[(CH2)q-NH]r-H. In the above, M is the same as above, P is an integer of 0 to 10, q is an integer of 1 to 3, and r is an integer of 1 to 10)
A compound represented by (c) general formula

[0011]

[Chemical formula 10]

(wherein, X9 represents H, -CH2CO2M or -PO3MM, and X10 represents C1-5 alkyl, -C
O2M or -CH2CO2M, X11 is -CO2
M, -CH2CO2M, -PO3MM or -CH(OH
) represents CO2M, and X12 represents H or OH. In the above, M is the same as above), (d) a compound represented by the general formula

[0013]

[Chemical formula 11]

(wherein Z1, Z2, Z3 and Z4 are the same or different and each represents H, CH3, CONH2 or -C(
NH2)=NH. In the above, M is the same as above,
m represents an integer of 1 to 15. ), a compound represented by (
e) General formula

[0015]

[Chemical formula 12]

(wherein A is H, -OH, -SH, NH2
CO-, -COOM, amino group, -NH-C(NH2)
=NH, -ONH2, -CH(NH2)CO2H, RS
-, NH2CONH-,

[0017]

[Chemical formula 13]

[0018] or

[0019]

[Chemical formula 14]

Z5, Z6 and Z7 are the same or different and each represent H, CH3 or C2H5, and Z8 is NH
2 or OH. In the above, M is the same as above, R
represents C1-5 alkyl, l is an integer from 0 to 4, and k is 0
Or indicates 1. ), (f) a compound of general formula (IV) and/or general formula (V)
(g) at least one chelating agent selected from a dipeptide or tripeptide compound condensed with a compound of (g) a cyclic nitrogen compound;
The present invention relates to a catalyst solution for selective electroless plating of copper-based materials, characterized in that it consists of an aqueous solution containing 1 to 2 mol/l.

Palladium compounds used in the catalyst solution of the present invention include (NH4)2[PdCl6], (NH4)2[
PdCl4], [PdCl2(NH3)2], [PdI
2(NH3)2], [Pd(NO2)2(NH3)2]
, K2[PdCl6], K2[PdCl4], K2[P
d(NO2)4], Na2[PdCl4], Na2[P
d(NO2)4], PdBr2, PdCl2, PdI2
, Pd(NO3)2・2H2O, PdO, PdSO4,
PdS, [Pd(NH3)4]Cl2, [Pd(NH3)
)4](NO3)2, Pd(C2H3O2)2, Pd(
Examples include NO3)2, [Pd(NH3)4](OH)2, and the like. The amount of palladium compound added is 0.0001~
About 0.5 mol/l, preferably 0.0005 to 0.1
The amount may be about mol/l; if it is less than 0.0001 mol/l, a skip phenomenon tends to occur, and if it exceeds 0.5 mol/l, it becomes uneconomical, which is not preferable.

In the present invention, at least one of the compounds shown in (a) to (g) above is used as the chelating agent.

The alkyl group shown in (b), (c), (e) and (f) above preferably has 1 to 5 carbon atoms, specifically methyl, ethyl, propyl, Isopropyl, cyclopropyl, n-butyl, t-
Butyl, n-pentyl, isoamyl, neopentyl, etc. can be shown. Examples of the aralkyl group or aralkenyl group shown in (b) above include benzyl, phenethyl, phenylpropyl, cinnamyl, furfuryl, naphthylmethyl, naphthylethyl, pyridylmethyl, pyridylethyl, quinolylmethyl, and the like. The aryl group shown in (b) above includes phenyl, tolyl, mesityl, 1-naphthyl, 2-naphthyl,
Pyridyl, quinolyl, quinoxalyl, anthraquinolyl, thiazolyl, furyl, etc. can be shown.

Preferred specific examples of the chelating agent used in the present invention are shown below.

(a) General formula

[0026]

[Chemical formula 15]

Compounds represented by the formula (wherein X1, X2, X3, X4, X5 and n are the same as above): ethylenediaminetetraacetic acid (EDTA), ethylenediaminetetraacetic acid disodium salt (EDTA・2Na), hydroxyethylethylenediamine Triacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), ethylenediaminetetrapropionic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, etc.

(b) General formula

[0029]

[Chemical formula 16]

Compounds represented by (wherein X6, X7 and X8 are the same as above): nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), iminodipropionic acid (IDP)
), aminotrimethylenephosphonic acid, aminotrimethylenephosphonic acid pentasodium salt, methylamine, ethylamine, propylamine, dimethylamine, trimethylamine, dimethylethylamine, benzylamine, 2-naphthylamine, isobutylamine, isoamylamine,
Methylenediamine, ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, diethylenetriamine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, cinnamylamine, p-methoxycinnamylamine, ammonia, etc.

(c) General formula

[0032]

[Chemical formula 17]

(wherein, X9, X10, X11 and X12
are the same as above): 1-hydroxyethylidene-1,1-diphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid trisodium salt, citric acid, tartaric acid, malic acid, malonic acid, etc. (d) General formula

[0034]

[Chemical formula 18]

Compounds represented by the formula (wherein Z1, Z2, Z3, Z4, M and m are the same as above): glycine, alanine, N-methylglycine, glycocyamine, dimethylglycine, hydantoic acid, aminovaleric acid, β -Alanine etc.

(e) General formula

[0037]

[Chemical formula 19]

Compounds represented by the formula (wherein A, Z5, Z6, Z7, M, l and k are the same as above): valine, norvaline, leucine, norleucine, isoleucine, serine, cysteine, asparagine, aspartic acid, glutamic acid , ornithine, lysine, arginine, glutamine, diaminopropionic acid, citrulline, hydroxy-
L-lysine, diaminobutyric acid, aminoadipic acid, canalin, kynurenine, diaminopimelic acid, homocysteine, histidine, methionine, etc.

(f) Dipeptide or tripeptide compound condensed with the compound of general formula (IV) and/or the compound of general formula (V): aspartyl-histidine, alanyl-
Alanine, alanyl-β-alanine, β-alanyl-β
-alanine, glycyl-lysine, alanyl-ornithine, lysyl-lysine, ornityl-ornithine, glycyl-ornithine, β-alanyl-lysyl-lysine, ornityl-lysyl-lysine, glycyl-ornithy-ornithine, etc.

(g) Cyclic nitrogen compound: imidazoline, 2
, 4,5-triphenyl-2-imidazoline, 2,2'
-bis(2-imidazoline), pyridine, morpholine,
Bipyridyl, pyrazole, triazine, etc.

In the catalyst liquid of the present invention, the above-mentioned (a) to (g)
) may be used, and the amount thereof may be about 0.0001 to 2 mol/l, preferably about 0.0005 to 0.4 mol/l, in the catalyst solution. . If it is less than 0.0001 mol/l, a bridging phenomenon tends to occur, and if it exceeds about 2 mol/l, it becomes uneconomical, which is not preferable.

The method for preparing the catalyst solution of the present invention is not particularly limited; for example, a method in which a palladium compound is directly added to and dissolved in an aqueous solution of a chelating agent, a method in which a palladium compound is dissolved in an acid such as HCl or H2SO4, etc. A method of mixing the chelating agent with an aqueous solution of a chelating agent, etc. can be adopted.

The pH of the catalyst solution of the present invention is not particularly limited, but when adjusting the pH, an acid such as HCl or H2SO4 or an alkali compound such as NaOH may be used as necessary.

[0044] Furthermore, a nonionic, cationic, anionic, or amphoteric surfactant may be added to the catalyst liquid, thereby lowering the surface tension of the catalyst liquid and improving the surface of the copper-based material. catalytic activity can be made uniform. Furthermore, by adding thioureas, the deposition potential of the copper-based material can be lowered and substitution with palladium can be promoted. Examples of thioureas include thiourea, dimethylthiourea, trimethylthiourea, allylthiourea, acetylthiourea, ethylenethiourea, and phenylthiourea. In addition, as a pH buffer, hydrochloric acid-potassium chloride, potassium hydrogen phthalate-hydrochloric acid, potassium hydrogen phthalate-sodium hydroxide, potassium dihydrogen phosphate-sodium hydroxide, boric acid-sodium hydroxide, sodium hydrogen carbonate-water Sodium oxide, disodium hydrogen phosphate-sodium hydroxide, sodium hydroxide-potassium chloride, tris(hydroxymethyl)aminomethane-hydrochloric acid, sodium acetate-acetic acid, etc. can also be added. Surfactants, thioureas, and pH buffers can be used alone or in appropriate combinations, if necessary.

The catalytic solution of the present invention selectively activates copper-based materials, and can be used to catalytically activate copper-based materials even for materials in which an insulator and a conductor are integrated, such as printed circuit boards, ceramic substrates, and chip parts. By selectively catalytically activating only the copper-based material, it becomes possible to perform electroless plating only on the copper-based material.

Copper-based materials that can be applied include copper, brass, phosphor bronze, nickel silver, etc., and these copper materials can be coated on these materials themselves or on various substrates by plating, vapor deposition, paste, etc. It can be applied to products that have a film formed from these materials.

The treatment method using the catalyst liquid of the present invention may be the same as the treatment using a normal catalyst liquid, and the liquid temperature is about 10 to 90°C,
Preferably, the object to be treated may be immersed in the catalyst liquid at a temperature of about 25 to 70°C for about 10 seconds to 10 minutes. If the liquid temperature is too low, a skip phenomenon tends to occur, while if the liquid temperature is too high, a bridge phenomenon tends to occur, so care must be taken.

[0048] By performing electroless plating after activation with a catalyst solution, a plating film can be selectively formed on the copper-based material. Although the catalyst solution of the present invention is not particularly limited as an electroless plating solution, it is particularly effective when using an electroless plating solution for Ni, Pd, Pd-Ni, etc. that uses a hypophosphorous acid compound as a reducing agent. .

When the catalyst solution of the present invention is used, pretreatments such as degreasing and pickling may be performed according to conventional methods, and the electroless plating conditions may also be the same as usual.

[0050]

[Effects of the Invention] By using the catalyst liquid of the present invention, electroless plating can be performed selectively only on copper-based materials, and materials consisting of insulators and conductors such as printed circuit boards, ceramic substrates, chip parts, etc. Also, the skip phenomenon,
It becomes possible to form a good plating film only on the conductor portion without causing a bridging phenomenon or the like.

[0051]

[Examples] The present invention will be explained in more detail below with reference to Examples.

[0052]

[Example 1] Drilling holes in a glass epoxy copper clad laminate,
After performing electroless copper plating and electrolytic copper plating, an etching resist layer is formed, and then etching, etching resist layer peeling, solder resist printing, character printing,
The following treatment was performed on a 100 x 170 x 16 mm copper-plated through-hole printed wiring board for mixed mounting of double-sided surface mount components and single-sided insertion type components obtained through the external shape processing step.

After degreasing and pickling the printed wiring board,
Ammonium persulfate 150g/l aqueous solution at 30℃
Soft etching was performed by dipping for a second, and then after pickling, a catalyst was applied using the catalyst liquid composition and conditions shown in Table 1. Next, electroless plating was performed using Ni, Pd, and Pd-Ni having the following compositions, and the occurrence of skip and bridge phenomena was examined. In the case of evaluation of skip phenomenon,
The plating time was 30 seconds, and in the case of bridging phenomenon evaluation, the plating time was 30 minutes.

Electroless Ni plating solution Nickel sulfate (hexahydrate)
2
0g/l malic acid

20g/l Sodium hypophosphite (monohydrate)
30g/l lead acetate (trihydrate)

1mg/lp
H (adjusted with ammonia water)
6 Bath temperature


85℃ precipitation rate

Approximately 8μm/h Electroless Pd plating solution Palladium chloride
0
．． 01 mol/l ethylenediamine

0.08 mol/l thiodiglycolic acid

20mg/l Sodium hypophosphite
0.06 mol/
l pH

8 Bath temperature

50℃
Deposition rate

Approximately 1μm/h Electroless Pd-Ni plating solution Palladium chloride
0
．． 01 mol/l nickel chloride

0.1 mol/l ethylenediamine
0.08 mol/l thiodiglycolic acid
20
mg/l Sodium hypophosphite

0.06 mol/l pH

8 Bath temperature

50℃ precipitation rate

Approximately 2μm/h

[0055]

[Table 1]

As a result of the above test, No. 1 to which no chelating agent was added. When catalyst liquids 1 to 3 are used, Ni
, Pd, and Pd-Ni, no skip phenomenon was observed, but many bridge phenomena were observed. On the other hand, No. 1, which is the catalyst liquid of the present invention. When catalyst liquids Nos. 4 to 39 were used, no skip phenomenon or bridging phenomenon was observed in all cases.

Claims (1)

[Claims] Claim 1: (I) Palladium compound 0.0001
~0.5 mol/l, and (II) (a) general formula [Formula 1] (wherein, X1, X2 and X3 are each the same or different,
-CH2CO2M, -CH2PO3MM, -CH(CH
3) Indicates CO2M or -CH2CH2CO2M, X4
-CH2CO2M, -CH2PO3MM, -CH2C
H2OH, -CH(CH3)CO2M or -CH2CH
2CO2M, X5 is H, -CH2CO2M, -C
H2PO3MM, -CH(CH3)CO2M or -CH
2CH2CO2M is shown. In the above, M are the same or different and each represents H, K, Na or NH4, and n represents an integer of 0 to 2), (b) a compound represented by the general formula: X6 and X7 are the same or different, and each is H,
C1-5 alkyl, aralkyl, aralkenyl, aryl, -CH2CO2M, -CH(CH3)CO2M, -
CH2CH2CO2M, -CH2PO3MM or -CH
2CH2OH, X8 is H, C1-5 alkyl,
Aralkyl, aryl, -CH2CO2M, -CH(C
H3) CO2M, -CH2CH2CO2M, -CH2P
O3MM, -CH2CH2OH, -(CH2)p-NH
2 or -[(CH2)q-NH]r-H. In the above, M is the same as above, P is an integer from 0 to 10, and q is 1
(c) a compound represented by the general formula [Formula 3] (wherein, X9 is H, -CH2CO2M or -PO3MM);
and X10 is C1-5 alkyl, -CO2M or -
CH2CO2M is shown, X11 is -CO2M, -CH2
It represents CO2M, -PO3MM or -CH(OH)CO2M, and X12 represents H or OH. In the above, M is the same as above), (d) a compound represented by the general formula: NH2)=N
Indicates H. In the above, M is the same as above, m is 1 to 15
indicates an integer. ), (e) a compound represented by the general formula [Chemical formula 5] (wherein A is H, -OH, -SH, NH2CO-, -C
OOM, amino group, -NHC(NH2)=NH, -ON
H2, -CH(NH2)CO2H, RS-, NH2CO
NH-, [Chemical formula 6] or [Chemical formula 7], and Z5, Z6 and Z7 are the same or different and each represents H
, CH3 or C2H5, and Z8 represents NH2 or OH. In the above, M is the same as above, R represents C1-5 alkyl, l is an integer of 0 to 4, and k represents 0 or 1. ), (f) a compound of general formula (IV) and/or general formula (V)
(g) at least one chelating agent selected from a dipeptide or tripeptide compound condensed with a compound of (g) a cyclic nitrogen compound;
A catalyst solution for selective electroless plating of copper-based materials, characterized in that it consists of an aqueous solution containing 1 to 2 mol/l.