Note: Descriptions are shown in the official language in which they were submitted.
-"` Z0088(~1
The present invention relates to a process for the
pretreatment of plastics, particularly of polyether sulphones for
adhesive chemical metallization. By polyether sulphone are meant
any plastics or industrial products that contain S02r ether and
phenylene groups.
By pretreatment is meant the preparation or change of
the plastics surface including the filler (for example, glass
fibers) to completely and homogeneously assure the activation
(seeding with (noble) metals or carbon) and thus posltively
influencing the chemical metallization.
:l.U
The pretreatment of plastic based on polyesters,
polyamides, sulphones, polyurethanes, and the like, for chemical
metallization is known. This includes, for example, the
1~ treatment with alkaline purifiers, with S03 in the gas phase,
with solvents containing wetting agents or with water-soluble
organic dissolving intermediaries which solvate hydroxyl ions.
However, for the pretreatment of plastlcs based on
2U polyether sulphones, these methods of treatment are unsuitable
since they result only in an unsatisfactory films.
The present invention provides a method of pretreatment
for the above-mentioned kind of plastics, i.e., a pretreatment
allowing an adhesive chemical metallization.
2~
According to the present invention there is provided a
process for the pretreatment of plastics, for the adheslve
chemical metallization, wherein the plastics, dissolved wlth a
quaternary base, are treated in an organic solvent. Suitably a 30 Cl-C4 alkyl ammonium hydroxide, aryl ammonlum hydroxide, vinyl
triaryl phosphonium hydroxide, tetraphenyl phosphonium hydroxlde
or tetraphenyl arsonium hydroxide is used as quaternary base.
Desirably an organic solvent that is soluble in water, alcohols
or ethers is used.
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: 2008801
The process according to the present invention
advantageously allows an adhesive metallization of the surface of
plastics.
Thus, the plastics are hydrophilized with surprising
intensity and are prepared for the activation in a special manner
!i while the surfaces simultaneously swell up and the attack of the
etching agent is facilitated and thus reinforced.
By polyether sulphone is meant a thermoplastic
polyether sulphone that contains aromatic ether groups as well
u as, with periodic recurrence, SO2 groups and aromatic and/or
aromatic bisphenol-A groups in the chain. On the market these
products are known as polysulphones, polyarylene, (or
polyphenylene) sulphones and polyether sulphones. When desired,
these plastics may contain a glass fiber component or a mineral
1~ component or mixture of these two components.
The following quaternary bases to be used according to
the present invention are mentioned specifically:
2U
; ammonium hydroxide
alkyl ammonlum hydroxide
aryl ammonlum hydroxide
2~ vlnyl trlaryl phosphonlum hydroxide
tetraphenyl phosphonium hydroxide and
tetraphenyl arsonlum hydroxlde.
Furthermore, an outstanding effect is displayed by
; tetramethyl ammonium hydroxide.
The following bases and/or thelr salts whlch are used
~ointly wlth hydroxyl ions are suitable compounds:
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-`~ 20088(~1
alkyl benzyl dimethyl ammonium chloride
(-)-N-benzyl quinlnium chloride :
benzyl trlbutyl ammonlum bromlde
benzyl tributyl ammonium chloride
benzyl triethyl ammonium chloride
benzyl triethyl ammonium hydroxide
benzyl trimethyl ammonium chloride
benzyl trimethyl ammonium hydroxide
:Iu butyl triphenyl phosphonium chlorlde
(-)-N-dodecyl-N-methyl ephedrinlum bromlde
ethyl hexadecyl dlmethyl ammonium bromide
ethyl trioctyl phosphonium bromide
hexadecyl trlmethyl ammonium bromide
hexadecyl trimethyl ammonium chloride
. methyl trioctyl ammonium chloride
tetrabutyl ammonium fluoride trlhydrate
.. tetrabutyl ammonium hydrogen sulphate
tetrabutyl ammonium hydroxlde
;; tetrabutyl ammonlum lodide
2~ tetrabutyl ammonlum tetrafluoroborate
tetrabutyl ammonium phosphonlum bromlde
tetrabutyl phosphonlum chlorlde
tetraethyl ammonlum bromlde
3U tetraethyl ammonlum chlorlde
tetraethyl ammonlum cyanlde
tetraethyl ammonlum hydroxlde
tetraethyl ammonlum fluroborate
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tetraoctyl ammonium bromide
tetraphenyl phosphonium bromide
tetraphenyl phosphonium chloride :
tetrapropyl ammonium bromide
tetrabutyl hexadecyl phosphonium bromide
tributyl methyl ammonium chloride .
tetrapentyl ammonium bromide
tetramethyl ammonium hydroxide
:I.u tetrapropyl ammonium hydroxide (aqueous solution)
tetrahexyl ammonium bromide
tetradecyl trimethyl ammonium bromide
methyl tridecyl ammonium chloride
1~;
These compounds are used in concentrations of 0.05 to
200 g per litre.
:~ 2U It is understood that the pretreatment agents according
to the present invention can be applied as such - or when desired
in the form of their salts in the presence of hydroxyl ions, from
which the quaternary bases are liberated in the presence of
hydroxyl ions. .
For example, the following media are suitable as
organic solvents and/or dissolving intermediaries:
N-methyl formamlde
3~ N-methyl acetamlde
propylene carbonate
ethylene carbonate
acetonltrile
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dlmethyl sulphoxide
N,N-dimethyl formamide
dimethyl acetamide
N-methyl pyrrolidone
methylene chloride
acetic ethyl ester
1,4-dioxane
diethyl carbonate
:Iu ~ -butyrolactone
ethylene glycol
ethylene glycol monomethyl ether
ethylene glycol monoethyl ether
ethylene glycol monobutyl ether
ethylene glycol monolsopropyl ether
ethylene glycol monoisobutyl ether
2U ethylene glycol mono-tert-butyl ether
ethylene glycol mono-n-hexyl ether
ethylene glycol mono (2-aminoethyl)-ether
ethylene glycol diglycide ether
z~ ethylene glycol monophenyl ether
ethylene glycol monoacetate
ethylene glycol diacetate
ethylene glycol monoethyl ether-acetate
3U ethylene glycol monoallyl ether
ethylene glycol dimethyl ether
ethylene glycol monobutyl ether acetate
ethylene glycol monobenzyl ether
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ethylene glycol monoisoamyl ether
methanol
ethanol
n-propanol
i-propanol
n-butanol
glycerol
glycerol aldehyde
:Iu glycerol glycide ~:
glycerol monomethyl ether
glycerol monoethyl ether
dlethylene glycol
1~ dlethylene glycol monomethyl ether
diethylene glycol monoethyl ether
dlethylene glycol monobutyl ether
2U diethylene glycol dlethyl ether
dlethylene glycol dimethyl ether
trlethylene glycol
trlethylene glycol monoethyl ether
2~ triethylene glycol monomethyl ether
The solvents are suitably used in concentratlons of 10
to 100% by weight. When deslred, these solvents can also be
mixed with water or low alcohols.
3u
The solutions to be used according to the present
invention are alkaline and have a pH value of 11 to 14.
The treatment of the plastics is suitably carried out
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at temperatures of lo to 90C, preferably at 25C.
The process according to the present invention is
carried out by conventional immersion of the plastic articles,
such as sheets, in;ection moulded articles, copper-laminated
extruded panels or moulded parts, in the pretreatment solution
according to the present invention.
The treatment time depends on the plastics concerned
and usually is 3 to 10 minutes, preferably 5 minutes. The
u pretreated parts are then rinsed, whereupon they can be further
processed. On an article thus pretreated water no longer beads.
A substantial effect for a good adhesion can be
attained even after the solderlng passage when on completing the
1~ pretreatment the plastics are roughened by means of an etching
bath, preferably a bath containing an acid oxidizing agent, and,
are then further processed in the usual manner. Apart from
chromosulphuric acid and chromic acid, chloric acid, hydrogen
peroxide and peroxodisulphuric acid can also be used as an acid
2U oxidizing agent.
k,
The activation and the chemical metallization of the
plastic articles pretreated according to the present invention
are carried out in a convention manner,
2~
The activation can be carried out, for example, by
means of a palladium activator, which is present in the ionic
form or in the form of colloidal pparticles. When required, the
palladium ions are reduced on the substrate surfaces, for
3U example, by the action of dimethyl aminoborane or sodlum
- hydroxide. Colloidal palladium nuclei can be freed from the
protective colloid by means of borofluoric acid or caustic soda
solutlon.
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The surfaces thus treated are then chemically
metallized by means of conventional methods, using currentless
nickel, cobalt, silver, palladium, tin, gold or copper baths.
For example, the copper - or nickel-plated plastics article can
be subjected to tempering at a temperature of 80 to 120C for the
purpose of strengthening the bond and, when required, for
removing water or solvent. This can take up to approximately one
hour.
Depending on the required shape of the metallized
plastics articles the layer thickness of the metal can be
u chemically or galvanically reinforced and processed by means of
conventional structuring methods. The composite metal-plastics
is distinguished by its great stability and the adhesive strength
of the metal layer on the substrate surface.
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The process according to the present invention is
particularly suitable for the production of printed circuits in
electrical engineering and electronics.
The printed circuits thus produced have the special
advantage of a low microroughness and high adhesive strength.
This is a great aavantage.
The plastics articles produced according to the present
invention have high adhesive strength values of up to 15N/cm.
2~
A partlcularly surprising advantage of the present
lnventlon lles ln that not only does the attack of the hydroxide
ions dissolved in the solvent and/or swelling agent increase the
adhesive strength values of the composite system metal-plastics
3U but it also produced uniformly reproducible adhesive strength
values. Thus, even at lengthy operating cycles no poor adhesive
strength values were observed in the composite metal-plastics, as
was occasionally noticed ln a pretreatment of the plastlcs with a
swelling agent alone (chromosulphuric acid).
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The present invention will be illustrated by the
following Examples:
Example 1
A polyether-sulphone panel having a glass-fiber component of 20%
!i iS immersed in a solution of loog/litre of tetramethyl ammonium
hydroxide in N,N-dimethyl formamide/isopropanol (70:30) for 30
seconds at room temperature and then rinsed, whereupon it is
immersed for 12 minutes in a commercial sulphuric chromium-VI-
oxide etching bath having a temperature of 70C. Following the
-~ etching action the panel is rinsed for 2 minutes and the
hexavalent chromium still present on the substrate surface is
reduced to chromium-III by means of a 10% aqueous NaHSO3
solution.
1~On completion of the treatment, the substrate surface
is very slightly roughened and is found to be well wetted with
the water. Thereafter the pane~ is activated with an iongenic
palladlum-II complex, reduced with sodium boron hydride and
chemically copper-plated in a conventional thin copper bath to a
2~ layer thickness of 0.2 ~m. On tempering the chemically copper-
plated polyether-sulphonate panel for one hour at 100C it ls
holohedrally copper-plated in a commercial sulphuric copper
electrolyte to a layer thickness of 35 ~m. The copper coating,
which is finally tempered for 2 hours at 130C, has an adhesive
2~strength value of 14 to 15 N/cm ln the peel test (DIN Standard 53
494).
Example 2
3~ A polyether-sulphone panel having a glass-fiber component of 10%
and a mineral component of 10% is immersed in a solution of
80g/litre of tetramethyl ammonium hydroxide in N,N-dimethyl
formamide/isopropanol (70:30) for 30 seconds at room temperature
analogously to Example 1 and is copper-coated to a layer
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thickness 35 ~ m as described in Example 1.
The adhesive strength value according to DIN Standard
53 494 is 12 to 13 N/cm.
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; Example 3
A polyether-sulphone panel having a glass fiber component of 20%
is immersed for 1 minute in a solution of N,N-dimethyl
formamide/H2O (90:10), at room temperature, rinsed and then
Lu immersed for 15 minutes in a commercial chromosulphuric acid
etching solution having a temperature of 70C.
As described in Example 1, the hydrophilic roughened
surface is reinforced to a copper layer thickness of 35 ~ m. The
adhesive strength value according to DIN Standard 53 494 is 10
N/cm. A comparison of the Examples 3 and 4 clearly shows the
effect of the substance tetramethyl ammonium hydroxide on the
adhesive strength of the composite copper-polyether sulphone.
2U
Example 4
A polyether-sulphone panel having a glass fiber component of 30%
is immersed for 30 seconds in a solution of 40g/litre of
tetramethyl ammonium hydroxide in dimethyl sulphoxide/water
2~ (90 I0)~ rinsed and subsquently treated for 15 minutes in a
commercial sulphuric chromiun -VI- oxide etching solution having
a temperature of 65C.
The further sequence of operation up to the finlsh of
3~ 35~ m of galvanic copper ls evident from Example 1.
The adhesive strength value according to DIN Standard
- 53 494 is 9 to 11 N/cm.
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