CA1200157A - Process for strongly-bonded metallisation of polyimides - Google Patents

Abstract

ABSTRACT

A process for the strongly-bonded metallisation Or a polyimide surface by pre-treatment, activation and chemical metal deposition and also, if desired, elec-trolytic metal deposition, wherein the pre-treatment is carried out with an aqueous solution of an alkali metal hydroxide and, if desired, of an organic nitrogen-con-taining compound.
Shaped parts containing such a metallised surface are especially suitable for use in the field of elec-trical technology and electronics.

Description

5~7 ~Procas~ ~or ~trongly-bonded n~t~ ation o~ polyimides~

The preeent invention is concerned ~ith a procesc ~or ~he ~trongly-bonded metallisat~on oi a polyimid~
~r~aco by mean~ oi a pre-treatme~ oi the polyimid2 ~urfacc followed by actiYation an~ chemical and ~l~og i~ de~ired, electrolytic metal de~osi~ion~
It ia known to u!ge a chemical metalli~ation pro~
cedure ln order to metalli~e non-conductive article~0 In order to obtain a sufficle~tly strong adhe~ion it i~ neces~ary for the sur~ac~ oi such artlcles to be roughened by mechanical or chem~c~l ~eansO In the case oi ~ome plastic~ materlals thl3 i~ achievcd mainly by mean~ of an acid o~idative decomposit~on o~ the sur~ace~
but this method cannot be used ~or pla.Ytic~ materiale ba~ed on poly~midc~0 Thi~ i~ a grcat dicad~antase~ ~ince polyi~tde ~oll~
are being used advantageou~ly ~o ~ increasing e~tent i~ th~ ~lectronics ~leld ~n~tead o~ glas~-~ibre mat-t~ng impregnated with epo~y resin. Poly~ ide ~oil~ may b~
used9 ~n particular, ~hen co~ered ~th copper o~ both sid~o, for multipl~ layer circui~s, ~or e~ampls for BO-called ~multilayers~, ~inca they o~er considerab~y improv~d lnsula-tion valu~ and therefore at the ~am~
tctal thickness BUCh a multl laye~ can ~e much mors .~.
`~

~2~ 5'7 ~o~ressed tha~ a layer u5ing an epo~ resina Up untll the present time the appllcation o~ the copper ~a~ o~ cour~ been e~fe~ted by means o~ ~ BUit~
able adhesi~ since polyimides, ~lik~ the pla8tlc8 materials based on epo~y rssin~, are not Gapable o~
forming a ~trong bond ~i~h roll~d-o~ ~opper, and this results in un~a~ourable proce~sing characteristica.
Thus, multilayer~ o~ this type, during dl~lli n~ ~orm hollou space~ whlch, a~ter metallisation i8 carr~ed 10 out 7 can destro~ the ~hrough-contact at the tempera-ture OI the ~oldering operation (approximately 250C), or e~ce~s adheeive must be removed, which i3 done in a costly maDner by means o~ hi~hly concentrated chromlc acid~
The problem upo~ which the pre~ent in~entio~ i8 based ha~, there~ore, been to develop a proce~ which allowe the stro~gly-bonded met~ tion o~ a poly-imide ~ur~ace without the u~e o~ an adhe~i~eO
Thi~ problem i~ now solved according to the p.ro~
ces~ oi the pre~ent tn~ention, as defined belowO
The present invention provides a process for the metallisation of a sur~ace composed o~ a polyimid~
wherei~ the sur~ace is pre-treated with an aqueo~
solutio~ o~ an ~lk~lt metal hydroxide and the resulti~g pre-treated ~ur~ace i8 ac~iYated and coated with a metal by chemical deposition.

5~

-- 3 ~

I~ de~ired~ the aqueou~ ~ol~tion us~d ~or the pre-treatment may also contai~ an organic nitrogen-contain-:Lng compoundO
Thu~7 the process of th~ present inv~ntion m~ke~5 pos~ible the ~tro~gly-bonded metalliRation oi a polr ~ide s~r~ace without the UBe 0~ a~ adhesiY~ by mean~
o~ a pre-treatment with an aqueous ~olutlon o~ an ~lk~ll metal b~ro~ide and~or an aqueous solutio~ o~
an ~ metal hydro~ide and an organic nitroge~
10 contQ~ n~ ~ compound~
If desired, after the coating of the poly~mide 6ur~ace with a metal b~ the chemical depositlon, th~
~ur~ace may be coated with a metal~ for e~ample copper, by electrodepos~tionO
Special embodiments o~ the process of the pre~ent inventio~ are that:
the solution used for the pre-trestment contains at least on~ ~1k~11 metal hydro~ide ~elected from lithium hydro~ide9 sodium hydroxide and pota~ium hydro~ids9 the oolution contains ~rom 5 to 600 gram~ per litre oP
the ~1k~1~ ~etal hydroside 9 preierably 50 grams per litre o~ the ~1k~1~ metal hydro~id~, the ~olution contain~ an organic n~ trogen-cont~n1n~
compou~d ~hich i~ a primary~ ~econdary or terttary amine9 the ~olution conta~ns an or~anic DltrOge~-oQ~in~n~
compound ~hich i~ an aliphat~c or cycloaliphatlc mo~o~

-- 4 ~

di~ or polyamins or a clsrivativo ~hereo~ contal~in~ at least one group selected from hydroxyl9 c~rbo3yl7 ~ulpho a~d phosphorylgroup~, an aromatic mono-, di-or polyamine or a derivatl~e thereo~ con-t~n~ne Rt 5 lea~t one ~roup selocted from h~droIyl 9 carbo~yl 7 sulpho and phoaphoryl ~roup~ or a heterocyclic mono-~dl-or polyamins or a deri~ativo therso~ containi~g at least one group selected ~rom hydro~yl 9 carbo~yl and s~pho groups~
the solution contains an organic nitro~en-containi~g compound ~hich i~ ~ mono-9 di- or polynuclear hetero-cyclic compound containin~ at least one nitrogen he-tero atom or a derlvative the.reof containing at lea~t one group selected from hydro~yl~ carbo~yl and ct~pho ~roup9, either o~ ~hlch compound~ a~ bs aubstitutefl by at lea~t one other sub~tltuent, preferahly an alky~
or nitrolo group9 the 801ut ion contRln~ an org~tlic nitro~en-coniaining compound which ia N,N,NI,Nl-tetrakis-(2~ .ro~ypropyl~-ethylenediam~ne 9 ethylenediami~etetraacetic acid ornitrilotriacetic acid~
the solution contains ~rom 5 to 30 &rams per li-tro~
preferably 20 grams per litro, o~ an or~anic nitro~en-containing compo~nd 9 the pre-trea~ment ie carried outa~atemperature -~ithln tho range o~ fro~ 15 ~o 30Cf preferably at 20G~

-- 5 ~

a~ter the pre-treatment. ha9 been carried out -the pol~-imlde surface i B activated ~n a kno~n manner, advan-tageously b~ mean~ o~ an activator conts~ning palladiu~9 a~ter the pre treatment and activatio~ have been carried out the pol~mide ~urfaca i8 chemically metallised ln a ~nown ~anner 9 preferably being copper- or nickel-plated9 and after the pre-treatment and metallisation have been carried out the polyimide surfaoe iB heated at a tem perature ~ithin the range o~ ~rom 70 to 140C~ pre-ferably at 1~0C.
The process accordi~g to the pre~ent invention make~ it possible ~n a s~rprisingly advanta~eous manner to produce a polyimide~met~l composite material9 preferably a polyimlde~copper composite material; which can bs used in the man~acture o~ ~.haped ~art,~ 9 pr~--ferably ~haped parts suitable ~or uBe i n t,he ~ield o~
electrlcal technology and electronic~O
~dditional advantages connected wl-th the po88i--bllity of producing ~uch a compos~te m~teri~l are thcavoidnnce of all so~rces o~ faults ~hich arise as a res~lt o~ u~in~ an adhesive~ The possibilit~ al~o becomes a~ailable o~ using a polyimide as the la~t layer i~ the production o~ a ba3e materi~l rOr semi~
addltlve teohnology, because ln thi~ ca~ al80 the uae o~ chro~ic acid ~Gr the remov~l o~ adhe~lve ia not ~2~

~ 6 --necessary~ In addition 9 there are the considerably ~mpro~ed electrical chsracteristic3~ which permit th~
lay~g-o~t oi much mor~ compact ~ring dlagrams than ie possible ~hen us~ng conventional ~he~lv~ agent~0 ~hu~, the present inventio~ includes ~ithin it~
scopa a body9 ~or e~ample a shaped part, cont~;n~n~ a ~riace metalli~ed by the proce~s o~ the present in~e~
tion~
~9 polyimides~ there are to be understood all ~uch plastic~ mater~als~ ~or example those de~cr~bed in ~1lr~nnfl Encgkl~p~die der technischen ~hemie, 1~70V`
~upplemen~ry Yolume, pp. 266 to 268 and pp. 318 to ~19, publlshed by Verlag Urban ~ ~chwarzenberg, Munic.h, Berlin~ Vienna.
These can be manu~actured ~n a manner Xnown per for e~ample by the reaction oi carbo~yllc acid anhydrlde~ with aromatic ~m ~ n e~.
They are mainly linear9 highly heat-~table pla~tic3 materials of the general formula CO ~ CO ~
\c~L~ ~ 3 ~3~)~l57 The proce6s oi the present invention iB advan-tageously used for the metallisation of the sur~aca o~
polyimide ~oi 18 .
It should be understood that not onl~ pla3tic~
material~ compo~ed of only a polyimide can be metal-lissd by th~ process of the pre~ent inYention, ~ut Pl 80 tho~e which are~ ~or e~amplep coated on one ~id~
~ith another plastic~ material.
~3 the organic nitrogen-cont~n~ne compounds th~t can be used in the aqueous solution used ~or the pre-treatment ~n the process oi the present invention, the ~ollowing may be mentioned by way of e~ample:
PIethylamine, ethglamine, propylamine~ butylamine, ethylene~1~m~ne~ propylene~mine, isopropylene~m~n~?
tetramethylene~ m~ n e, octamethylene~m1~e 9 piperidi~e3 pipera~ine, p~rrolidine, benzylamine, diethylenediam~ine, ethylene~m~netetraacetic a^id, butylene~mln~
tetraacetic acid~ hexamethylene~mlnetetraacetic acid9 octamethylene~ ~m~ netetraacetic acid, nitrilotriacetic acid, iminodiacetic acid, ethylene~ ~m~ ne-N,Nt-dlpro-pio~ic acid, he~amethylene~m~ne-N?N~-dipropionic acid, ethylenefl~mtne-tetraki~isopropanol, ethylenediamin~-tetrakis~et~anol9 N,N,N',~-tetrakis-(2-hydroxypropyl~-ethylene~mine9 trie~hanolamine, ethanolamin~
phe~ylenediami~e9 8n~1 ~ne, toluidln~ triethylamlne9 tributylamine~ N~N7~t,~l-tetramethyl-ethylene~m~n~g dimethy~ ethylened~m~ne, N9~-d~me~hyl-ethylene_ d 1 ~ml ne, ~-methylethylene~P~ n e, diethylamlne and dibutglamine~
Imidazol~ 9 l-mcthylimida~.ole, l-propylimidazole, 2,4-d~methyl~ mi dazole, 4-methyli 1~zole 9 2-i80propyl-imldazole t 2-phenylimidazole, l-benzylimiaazole 9 ~-imids~olopropionio acid, 1,2-dimethyl~ ~d~Y,ol~
methyl-2 hydro~ymethylimidazols, 4-sulphoimidazole;

2-methyl-4-sulphoim~dazole, 2-(~ulphophenyl)-~ m~ d~ole~
0 2-i80propyl-4 ~ulphoimidazole, l-~-propyl S_~U1PhO-~ ml d~.ole 9 1-n-propyl-4-~ulphoimidazole, 1,2-bi~
imidazol~l)-ethane, l-(g-sulphophenyl)-imidazole~
hist~dine9 2-(imidazoloethyl)-pyridi~e~ 1-(2~-amino-ethyl)-imidazole hydrochlor~de~ 1-(3 7 -aminopropyl)-imidazole hydrochloride, 1-methy1-2-carbo~ymethyl-imidazole, 2-(E-~ulphophenyl)-4 ~ulphoimidazole, 1-methyl-2 sulphoimidazole, 2-~ulpho~midazole, 1,2-bie~
~ meth~1-5~ imidazolyl~-e~hane, 5-~ulphoben~.l m~ ~
zol~, 5 ~rr~di~ulphobQn~.~ m~ dazole, 1~2-bis-[5'-sulpho-benz~m~dazolyl-t2')~-ethane, 194-bi~-[5'-~ulphobenz-imidazolyl-(2~)]-butane, polyvinyl{~ r.ole (degree oI polymeri~atio~ = 2 to 500), polyally~i m~ .ol~
(degree of polymeri~ation = 2 to 5003~ 3~5-dimethyl~
p~razole, 4-~ulphopyrazole, l-meth~lpyrazole, me~hylpyrazole~ dimethylpyrazQle~ l-phenylp~razole 9 l-carbo~ymethylpyrazole, l-ca~boIyethylpyrazole7 1~

~;~t~ 5~7 _ g _ amlnoethylpyrazole hydrochloride~ l-~minopropylpyrazole hydrochlor~de, 3,~-dipyrazolyl, 1,~-dlmethy1-5-hydro~y-pyrazole, l-phenyl-~-methyl-5-hydro~ zole, l-(E-sul~hophenyl~ methyl 5-hydro~y~ azols 9 l-(m-~ulpho phenyl)-~-meth~1-5~hydro~ylazol~, l-(E~aminophenyl)-~-methyl 5-hydro~y~y.a~le, 1- ~ chlorophenyl)~-methyl-5-hydro~y~ylazolet 1- ~ ~ulphopheny1)-3-carbo~y-5~hydroxypyra~.ole, 1,2-bis-(1'-pyrazolyl)-ethane, 7-s~phobenzpyrazole, l-carbo~yethylbenzpyrazole, 1,2-bi~-(3'-pyrazolyl)-ethane and di-(3-pyrazolyl)-methane.
Pyridine, 2-aminopyridine, 3-aminopyridine~ 4-amino-pyridine, 2-hydro~y~yridin~, 3-hydro~ypyridine, 4-hydro~y~y.-ldine, 2y6-~i~m~nopyridine, 2,~d~m~no-pyridine~ 3~4~ m1nopyridine~ 2-a~inomethylpyridine9 ~-aminomethylp~ridine, 4-~m~nomethylpyridine~ 4-piCG-llne, 3-picolino, 2-picoline, 2,6-lutidin~, 2,4-luti-dine, 3-pyridinesulphonic acid, 2,2'-dipyridyl, 1,2-di-(2'-pyrldyl), 2 t 2~-dipyr~dylmethane, 2, 2 ~ -dipyri-dylamineJ 1,2-dihydro~y-1,2-di-(2'-pyridyl)-eth ne, 2~2'-dipyridylethylene, 4g4'-dipyridyleth~lene, 3-sulpho-3,~'~dipyridyl and ly2-di=(4'-pyridyl~-ethane.
2-Aminopyr1~ n e, 2,4,6-triaminopyr~midine, 19 4-di methylpyrim~din~ 19 5-d~methylpyrlmidine, 4 D 5-d1 methylp~rimldine 9 4,6-dimethylpyrimidlne 9 2~4-bi~
(diethylamino~-p ~m~ne, 3,6~bis-(dimethyl~mino~
pyr~ mi ~ ~ ne ~ 3~6-bi3-(ethyla~ino)-p~rimidine, 2-hydroxy-s~

pyrlmidine, 4-hyd~oly~y~ n~, 4,6--dihydro~yp~rimidine, barbituric acid 9 cyto eine, pyr~ m~ ~ { n e~ bis-(2-methyl-4-pyrimid~l~; 2,2'-dipyrimidyl, 494'-dipyrimid~1, uraell, 5-methylcytosine~ 2-methylp~rl mt ~ine~ 2-ethylpyr~ ml ~ ~ ne, 2-phenylpyrl~a~ne~ 2-am~no~6-ethylp~rim~dine, 2-~m~no ~-~ethylp~rl 1~ne~ 2-amino-5-metho~y~y~tm~n0~ 2 aminoD4-hydro~ L~id~ne~ 2-carbo~y~rt~ ne~ 5-carbo~ymethylpyrl ml ~ ~tne, 2~carbo~ymethy1 5J6-dimethyl~
pyrimldine, 2-methy1-5-carbo~ymethyl-pyrimidlne, pyri-dazine, 3-methylpyridazineg pyrszine, 2,3p5,6-tetra-methylpyrazine, 2,5-dimethyl-6~hydro~ypyrazlne, 2 hydro~y~yLazine and 2-aminopyrazineO
~rotropine, 2,6-~i~mlno-4-methyltriazine~-(1,3~5)p ~,6;;
~m~no-4-ethyltriazine-tl~3~5)~ 2,6-diamino-4-propyl_ triazine-(1,3,5~, 2p6~ m~no-4~carbo~ymeth~1tr~.1ne (1,3t53, 2"6~ mlno-4-carbo~c;yethyltriazine-(1"3t5)~
2 s 6-d1 ~ m~ no-4-~ulphopropyltrlazine-(l~3 t 5~, mel ~m~ n~ ~
cyanuric acidp 2p4~6-tris~methyl~rlnotriazine-~l93~5)) 2,4,6-tris-ethylaminotriazine~ ,5), 2,4,6-tri~-20 dieth~l~m~rsotr~azine-(lp3,5)t b~9-~496~l~m~no-2-~ri;
azinyl~ 5)~-methane 9 1 ~ 2-bis-[4l,6 ~ m l notri 8z~nyl~ 3~ p55)]-ethane, 1,3-bi~-[4~6~ m~no 2~
triazinyl~ 3'~5~)~-propane, 1~2-bi3~4'~6~ Rm~no_ ~riazi~yl 2~-amino)-ethane~ 2~4~ minotriazine-(l93~5 2D4~t~no-6~ ulphophenyl)~trlazine-(lp3~5)p 2~4 diam~n~-6~ethyltr~1ne ~13~,5~p 2~4-d~hg~ro~y-6~meth~1 ~2~5'7 triazine-(193,5)9 cyanuric acid h~dro~y~thyl e~t~r9 2,4-dihydro~y-S-carboxymethyltriazine-(19~95~ 9 2-amino-4-carbo~ymethyl-6-n-butylnminotriazine-(1,395), 2-amino-4-carbo~y-6-n-butyll~m;notriazina-(1,3,5), 2-5 amino-4-carbo~yethyl-6-n-butyl ~ ml n otriazine-tl,~,5) 9 2-am~o 4-hydroæytr1~ ne~ ,5), 3-aminotr~ ne-~ 4~, 3-amino-5,6-dimethyltr~æine-(1,2,4), 4-hydro~y-5~6-dimethyltriazine-(1~2,4), 4-hydro~y-5-phenyltrlazine-(1,2 9 4), triazine-~1,2,4), ~ t 3'-bi3~
~5,6-dimethyltriaæinyl-(1,2,4)], ~,5-dihydroxytr1~æ~ne-( 1 9 2 ~ 4), 3,5-dihydro~y-6-methyltria~ine-(1,2,4), 3,5-dihydro~y-6-butyltriazine-(1,2,4), 3~5-dihydroxy-6-phe~yltriazine-(1,2,4) and 3,5~dihydroxy-~-carbo3y-propyltrl~ ne-(1,2 7 4).
Trlazole-(1,2,4), 4-ethyltriazole-(1,2,4), 4-methyl-triazole (1,2,4~t 4-phenyltriaæole-(1,2~4), 3,4,5-trimethyltriazole-(1,2,4)9 4-(E~lphophenyl)-tri-azole-(1,2,4), 3-methyltriazole-(1,2,4 ?, 3-ethyltri-azole-(192,4)~ 3,5-dimethyltriazole-(1,2,4)) ~-phen~l-triazole-~1,2,4)~ 1-methyltriazole-(1,2,4), l-ethyl triazole~ 2,4), l-phenyltriazole (1,2,4) t 3-sulpho-triazole-(1,2~4), 3-aminotriazole-(1,2,4~, 395-di-aminotriazole-(1,2,4)~ 1,2-bis-(5'-~ulpho-3'-tr~a-zolyl)-etha~e~ 1,2-bis-(5'-amino~-~'-triazolyl~-eth3ne~
1,2-bis-(3l~triazolyl3-ethane~ 192-bl~ (4'~methyl-3l tria~olyl~ethane, bis-(3-triazolyl~-methane, bls-(5-S'7 ~ulpho~3-tr~azolyl)~methane9 bi~-(5-amino-3 triazolyl)-methane~ bio-(3-triazolyl)-methane9 b~s-(5-eulpho~3-triazolyl), bl~-(5-~mino-~-triazolyl~, 393'-bis-trl-azolyl9 1,2~ triazolyl)-ethane, 3--(2'-aminoe~hyl) triazole-~192,43, ~ (l-triazolyl)--propionic acid~ 1,4 bi~-(5'-aulpho-3~ ~riazol~l)-butane, 1,4-bis~t5~-amino-

3'-triazolyl~-butane 9 1-(3-sulphopropyl)-triazole~
(1,2,4), 1,2-bis-(4'-triazolyl)-ethane, l-methyltri-azole-(1,2,~)~ 1-ethyltriazole-(1,2,3), 2-ethyltri-azole~ 2,3), 2-propyltriazole-(lt2~), 1-(2'-car-boxyethyl~-triazole-(1,2,~)9 5-~ulphobenzotriazole, 5,7-disulphobenzotriazole, benzotriazole9 4-methyl-triazole-(1,2,3), 4,5-dimethyltriazole-(1,2,3), 4-but~ltriazole-(1~2,~ 4-phen~ltriazole-(1,2,3), 1 1~ (31-aminopropyl)-triazole-(lt2,3~, 1-(2'-aminoethyl~-triazole-(1,2,~) and 1,2 bis-(l'-triazolyl)-ethane~
Pyrrole, l-methylp~rrole, l-ethylpyrrole9 1-(2'-car-bo~yethyl)~pylrole, 2-methylpyrrole, 2,5-dimethyl~
py~ ole~ di-(2-pyrrolyl)-methane, di-(1-methyl-2-pyrrolyl)-methane9 2-ethylpyrrole and tryptophane.
Polyethyleneimi~e~ N,N-dimethyl-pol~vinylamine, poly-~in~limidazole, polyallyl1mi~zole, polyvinylpyridine~
polyvinylpyrrolidone9 polyvinylmorpholine, Polyvinyl~
morphol1none~ polyvinyl-5 alkyl-oxazolidone~ ~-poly~
vinyl~ ethylene-urea9 soya protein albumin~3 ethy lene~ Q ~1 n etetra-(methylpho~phonic acid) and he~a 5~7 methylphospho~etriamide~
It iB ~0 be under~tood that these compound~ ma~ be used singl~ or in the form o~ mi~ture~ with ona another, The 81 k~l ~ metal hydro~ides u~ed in the aqueou~
801utio~ used ior the pre-treatmeD~ in the proces~ o~
the pres~n~ ln~ention may be those obtained i~ the ~8ual maDner.
~ he process o~ the present i~entio~ may be carri~d out by dippingJ rinsing or wetting the polyimide ~ur-~aces to be metallised with the pre-treatment solutio~
u~ed according to the present invention. The pre-treat~ent temperature and the duration o~ the pre-treatment depend on the quallty o~ the pol~imide 9 thB
temperature being from appro~imately 15 to ~0C, pre fera~ly 20C, and the time ~rom appro~lmately 5 to 10 minuteaO
Tha solution used for the pre-treatment accordi~
to the present invention can be prepared in the deYired conoe~tration and oomposition shortly before the treat-me~t commence~ but stored ~olutions may, however9also be u~ed with equal suocessO If de~ired~ there ma~
al~o be added to the solutlon water-mlsclble organic solvents~ ~or e~ample alcohol~ or ester~, and thi~
al~o ~orm3 a po~sible embodiment of ~he process o~ th~
present ~n~ention~
~he part~ pre~treated accordi~g to the proces~

~2~ LS'7 of the pre~ent invention are rinsed a~ter the treat-ment, preferably with water, and are the~ re~dy for activation a~d ohemical met~ R~tion~ and also, if de~ired~ eleotrol~tic ~trengthening.
The usual acti~ator~, ad~a~tageou~ly based on a~
acti~ator co~t~ln~ne pQ11~1um~ and baths, preferably chemical copper or ~ickel plating baths, may be u~ed ~or th~s purpose~ For the optional electrolytic strengthen~ng, the u3ual electrolytes are al80 employed, for example a copper electrolyte.
It i~ ~ound to bo particularly favourable ~or the 6trong adherence of the depo~ited metal i~ the poly-imide ~ur~ace~ coated in accordance wi~h the process of the present invent~on are heated at a temperatur~
within the range o~ ~rom 70 to 140C, pre~erably at 130C, a~ter the metall~sation has been carried out, 0.2 to 2 hours being sufficient for this heating ~tepO
~ he composite materials produced by the process o~ the present in~ention posse~s, ~urpri~ingl~, a ~tabillty not hitherto ach~eved, and can onlg be to~, but not separated, by destroying the whole compositc material~ and this is o~ e~traordinary technical 1 m~
porta~ce.
The ~ollo~ing ~amples illustrate the in~ention:

., --~camPl~ 1 Polyimide ioil o~ a type normally used in the electrical industr~ wa~ treated for 30 minute~ la a solutio~ o~ 100 g oi pota~ium hydro~ide in 1 lltre oi water and then rin~ed. During the next step ~he yo1 wa~ actlvated in a know~ qnner with p~ um io~s.
~fter ri~ ~g in water, the rP~n1n~ ad80rbe~ p~
ions were reduced to p~ ium metal with an aqueo~s 1~ solution oi dimethylaminoborane. By being pre-treated in this manner, periect metallisation wa~achieved in a kno~n chemical copper bath u~ing ~or-maldehyde a~ the reduci~g agent. In order to ii2 tho copper that had been applled chemicallyg a tempering proce6R wa~ the~ carried out a~ 100C. After the tem-pering9 the e~tremely thin (0.5 ~m) copper coatlng WaBdeo~idized ~or a short time with 10~ ~y Yolume gtre~gth sulphuric acid and then strengthened to a thickne~ o~
40 ~m in the usual manner i~ a sulphuric ac~d electro-lytic copper ~ath. A test of the ~trensth of the ad-hesion o~ the metal coating gave a~ton~ ~h~n~ly good reslllts ~

Exam~le 2 A polyimide ~o~l ~as treated in an aquao~3 801u-t~on of 100 ~ litre of sodium hydro~ida and al8c 20 g/litre o~ ~,N,~ tetraki~-~2-hydroxypropyl3~
sthylene~ ~m~ ne; the treatment time waB thus reducsd r-~J
~V~ I

to 5 minutes a~ compared with Example lo The polyimide foil treated in this ~olution wa8 rinsed aftar 5 minute~' e~posure to the solutio~, &ctivated in a conventlon~l manner ~ith palladitlm, and reduced in a manner know~
per se a~ter a ~urt~er r~n~ln~ in water, and the ~ur-~ace ~as then coated chemically with copper. A~ter the tempering process which wa8 then carried out9 lasting ~or ~0 minute~ at a temperature o~ 80C, the thin chemically applied copper layer wa~ electrolyti-cally strengthened with copper in a known manner in asulphuric acid ~lectrol~te. ~he resultin~ polyimid~
foil pos~qessed an outqtanding stability and was in-~eparably bonded to the copper.

E~ample ~ pol~imlde foil was pre-treated in an aqueou~
solution o~ 20 ~ litre of ethylena~m1netetra~(methyl-phosphonic acid) and 50 ~ litrs og lithium hydroxide for 5 minutes.
The ~oil was then treated in a known manner with ~n alkaline activator cont~lnlne palladium~ then rinsed ln ~ater, and the adsorbed p~ um wa~ then reduc~d to p~ um metal in a 1~ aqueous solution o~ di~
methylami~oborane. ~ter being rin~ed agai~ in water, the activated ioil was nickel-plated to a thicknes~ o~
appro~mataly 002 ~m ~n a known manner by me~n~ o~ a (~l5i'7 chemical nickel-plating bath, and then ten~pered for 30 ~tnutes at 1~ 0CO ~or the subsequent deo~cidation oP
the ~ ace9 the latter wa~ treated Yor several minutes in 10~ by volume strength hydrochloric acid? then 5 rirLRed, and then strengthened w~th 40 ,um oi copper iIl a ~o~n mRnner in a sulphuric acid copper eleetrol;yte, ~he adhe~ioll o~ the nickel to the pol;srimide Wa8 e~tra~
ordinar;y"

Claims (32)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the metallisation of a surface composed of a polyimide, wherein the surface is pretreated with an aqueous solution of an alkali metal hydroxide and the resulting pretreated surface is activated and coated with a metal by chemical deposition.

2. A process as claimed in claim 1, wherein the solution used for the pretreatment contains at least one alkali metal hydroxide selected from lithium hydroxide, sodium hydroxide and potassium hydroxide.

3. A process as claimed in claim 1 or 2, wherein the solution used for the pretreatment contains 5 to 600 grams per litre of the alkali metal hydroxide.

4. A process as claimed in claim 1 or 2 wherein the solution used for the pretreatment contains 50 grams per litre of the alkali metal hydroxide.

5. A process as claimed in claim 1, wherein the solution used for the pretreatment also contains an organic nitrogen-containing compound.

6. A process as claimed in claim 5, wherein the organic nitrogen-containing compound is a primary, secondary or tertiary amine.

7. A process as claimed in claim 5, wherein the organic nitrogen-containing compound in an aliphatic or cycloaliphatic mono-, di- or polyamine or a deriva-tive thereof containing at least one group selected from hydroxyl, carboxyl, sulpho and phosphoryl groups.

8. A process as claimed in claim 5, wherein the organic nitrogen-containing compound is an aromatic mono-, di- or polyamine or a derivative thereof con-taining at least one group selected from hydroxyl, carboxyl sulpho and phosphoryl groups.

9. A process as claimed in claim 5, wherein the organic nitrogen-containing compound is a heterocyclic mono-, di- or polyamine or a derivative thereof con-taining at least one group selected from hydroxyl, carboxyl and sulpho groups.

10. A process as claimed in claim 5, wherein the organic nitrogen-containing compound is a mono-, di-or polynuclear heterocyclic compound containing at least one nitrogen hetero atom or a derivative thereof containing at least one group selected from hydroxyl, carboxyl and sulpho groups, each of which compounds may be substituted by at least one other substituent.

11. A process as claimed in claim 10, wherein the other substituent is an alkyl or nitrolo group.

12. A process as claimed in claim 5, wherein the organic nitrogen-containing compound is N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine, ethylene-diaminetetraacetic acid or nitrilotriacetic acid.

13. A process as claimed in claim 5, wherein the solution used for the pretreatment contains 5 to 30 grams per litre of the organic nitrogen-containing compound.

14. A process as claimed in claim 13, wherein the solution used for the pretreatment contains 20 grams per litre of the organic nitrogen-containing compound.

15. A process as claimed in claim 1, 2 or 5, wherein the solution used for the pretreatment also contains a water-miscible organic solvent.

16. A process as claimed in claim 1, wherein the pretreatment is carried out at a temperature within the range of from 15 to 30°C.

17. A process as claimed in claim 16, wherein the pretreatment is carried out at a temperature of 20°C.

18. A process as claimed in claim 1, 2 or 5, wherein the activation is carried out in a known manner.

19. A process as claimed in claim 1, 2 or 5, wherein the activation is carried out by means of an activator containing palladium.

20. A process as claimed in claim 1, 2 or 5, wherein the coating with a metal by chemical deposition is carried out in a conventional manner.

21. A process as claimed in claim 1, 2 or 5, wherein the metal deposited by the chemical deposition is copper.

22. A process as claimed in claim 1, 2 or 5, wherein the metal deposited by the chemical deposition is nickel.

23. A process as claimed in claim 1, wherein after the coating with a metal by chemical deposition the surface is heated at a temperature within the range of from 70 to 140°C.

24. A process as claimed in claim 23, wherein the heating is carried out at 130°C.

25. A process as claimed in claim 1, wherein after the coating with a metal by chemical deposition the surface is coated with a metal by electrodeposition.

26. A process as claimed in claim 25, wherein the metal deposited by the electrodeposition is copper.

27. A process as claimed in claim 1, 2 or 5, wherein the polyimide has the general formula

28. A process as claimed in claim 1, 2 or 5, wherein the surface composed of a polyimide is a surface of a polyimide foil.

29. A polyimide surface whenever metallised by the process claimed in claim 1.

30. A polyimide surface whenever coated with copper by the process claimed in claim 1.

31. A body containing a metallized surface as claimed in claim 29 or 30.

32. A shaped part containing a metallised surface as claimed in claim 29 or 30, the shaped part being suitable for use in the field of electrical technology and electronics.