Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~77~7~
~ 1 --
3-15l55/~
hotocurabl_ epoxy resln composltions which contain ~illerfl~ ~nd
the use thereof
The present invention relates to photocurable epoxy reflin composit-
ions which contains fillers, and to the use thereof, in particular
for the production of relief structure~, images or bond~.
EuropeaD patent appllcations 094 915 A2 and 109 851 A2 disclose
curable (polymerisable) compo~ition~ whlch contain a cationically
polymerisable orgaDic materlal and organo~etalllc initiator~ ~uch as
metallocene complexes. These patsnt applications i.a. generically
mention fillers as further possible additives, but epoxy resin
systems which contain fillers ~re not spQcifically disclosed.
Further, US patent specifications 3 9$8 Q56 and 3 989 644 discloae
radiation curable, especially W curable, composition~ for msking
conductive coatings, which compositions ~ay contain electrically
conductive metals such as silver co~ted glass spheres ~8 flller~ and
e.g. epoxy re~ins as organic resin binder. These co~positions may
al80 contain VV photosensitisers such as ketones, ben~oin and
benzoln derivative~ or aromatic onium salts of elements of Periodic
Group V a.
The present invention relates to novel photocurable epoxy resin
compositions which contain fillers said, co~positions comprising
(a) 5-90% by weight of an epoxy resin or mixture of epoxy resins,
which resin or resins do not contain ole~inically un~aturated C~C
double bonds,
.-
7t707(~
21489-6825
(b) 0.1 to 15~ by weight of at least one photoinitiator of
formula I
[(Rl)(R2M) ]~an ~ [LQm] q (I),
wherein a is 1 or 2 and each of n and ~ independently of the othe~
is an integer from 1 to 3,
M is the cation of a monovalent to trivalent metal of Periodic
Groups IVb to VIIb, VIII or Ib,
m is an integer corresponding to the valency of L + q and
Q is a halogen atom,
L is a divalent to heptavalent metal or non-metal,
R1 is a ~-arene and R is a ~-arene or the anion of a
~-arene, and
(c) 10-90% by weight of at least one finely particulate filler
selected from the group consisting of electrically conductive or
semiconductive fillers, thermally conductive or dielectric fillers,
fillers which influence the ferroelectric, ferromagnetic, piezo-
electric or electrochromic properties and fillers with luminescent
properties, the sum of all compounds being 100% by weight.
Surprisingly, the compositions of this invention can be
cured with visible as well as with UV light, even when they contain
high concentrations of fi.nely particulate filler. Further, -they
make it possible to produce coatings which can be fully cured even
if the layer thicknesses are substantial, although coating compo-
sitions containing electrically conductive fillers such as metal
powders, carbon black or graphite are usually only insufficiently
cured under UV light, because the light on the surface of the metal
, . .
~77~)t7~)
21489-6825
powders is strongly reflected or strongly absorbed by the carbon
- black or graphite.
2a -
~,~7~0t7~
-- 3 --
.
Suitable epoxy re~in~ (a) are pre~erably tho~e containlng on average
more than one group of the formula II
~0\
-~H-~ ~ H (II)
wherein each of Q' and Q~ i8 a hydrogen atom and Q~ i~ a hydrogen
atom or a methyl group, or Q' and Q~ together ars -CH2CH2~ or
-CH2CH2CH2- 8nd ~ iB a hydrogen stom, which group iR attached to
hetero atom, e.g. a sulfur atom and, preferably, to an oxygen or
nitrogen atom.
Typical examples of ~uch resin~ are polyglycidyl esters and poly-
(~-methylglycidyl) esters which are derived from aliphatic, cyclo-
aliphatic or ~romatic poly~arboxylic acids. Examples o~ 6~itable
polycarboxylic acids are: 3uccinic acid, glutsric acid, adipic acid,
plmelic acld, ~beric scid, azelaic scid, sebsclc acid, dimerised or
trimeri~ed linoleic acid, tetrahydr3phthslic acid, 4-methyltetrahy-
drophthalic acid, hexahydrophthalic acid, 4-mathylhexahydrophthalic
acid, phthalic acid, isophthalic acid and tcrephthalic acid.
Furth~r examples are polyglycidyl ethers and poly(~-methylglycldyl)
ethsrs which are obtained by reaoting a compound containing at le~t
two alcoholic and/or phenollc hydroxyl groups per molecule with
epichlorohydrin or with allyl chloride, and then epoxidi~ing the
reactioD product with a peracid.
Example~ of suitable polyol9 are: ethylene glycol, diethylene
glycol, poly(Qxyethylene) glycols, propane-1,2-diol, poly(oxypropyl-
ene) glycol B, propane-1,3-diol, butane-1,4-diol, poly(oxytetramcth-
ylene) glycol~, pentane-1,5-diol, hexane-2,4,6-triol, glycerol,
1,1,1-~rimethylolpropane, pentaerythritol and sorbitol; 1,3- and
1,4-cyclohexanediol, bis(4~hydroxycycloh~xyl)methane, 292-bis(4-
hydroxycyclohexyl)propane and l,1-bisthydroxym~thyl~ryolohex~3~ene;
N,N-bi~t2-hydroxyethyl)aniline and 4,4'-bi~(2-hydroxyethylamino)-
~L~7707()
-- 4 --
diphenylmethane; re~orcinol, hydroquinone, bi~(4-hydroxyphenyl)-
methane (bi~phenol F), 2,2-bi~(4-hydroxyphenyl)propane (bi~phenol
A), 2,2-bis(4-hydroxy-315-dlbromophenyl)propane (tetrabromobl~p~enol
A), 1,1,2,2-tetrakis(4-hydroxyphenyl)ethune, 4,4'-dlhydrnxyblphcnyl,
bi~(4-hydroxyphenyl)~ulfone, a~ well aR novolak~ of formaldehyde or
acetaldehyde ~nd phenol, chlorophenol or alkylphsnol~ containing up
to 9 carbon atoma in the alkyl moiety, preferably cre~ol and phenol
novolak~.
Suitable poly~N-glycidyl) compo~nds are products obtained by
dehydrochlorination of reaction products o~ epichlorohydrin and
amines containing at least two active hydrogen atoms bonded to amino
nitrogen atoms. Examples o$ suitable amines are: aniline, n-butyl-
amine, bis(4-amlnophenyl)methane, 1,3- and 1,4-xylylenediamine, 1,3-
and 1,4-bi~(aminomethyl)cyclohexane snd bis(4-methylaminophe-
nyl)methane. Purther s~itable compounds are: triglycidyl isocyanu-
rate, N,N'-diglycidyl der~vatives of cyclic alkylene ureas ~uch Ra
e~hylene urea and 1,3-propylene urea, or hydantoins such as 5,5-
dimethylhydantoin.
Examples of poly(S-glycidyl) compounds ~re the di-S-glycidyl
derivati~es of dithiols such a~ ethane-1,2-dithiol and bia(4-mer-
captomethylphenyl) ether.
Examples of epoxy resins containing one or more group~ of the
formula I}, wherein Q' and Q~ together sre a -cH2cH2- or -CHzCH2CH2-
group are bi~(2,3-epoxycyclopentyl) ether, 2,3-epo~ycyclopentyl
glycidyl ether, 1,2 bi~(2,3-epoxycyclopentyloxy)ethane, 394-epoxy-
6-methylcyclohexylmethyl-3',4'-epoxy-6'-methylcyclohexane carboxyl-
ate and 2-(3,4-epoxy)cyclohexyl-5,5-spiro(3',4'-epoxy~cyclohexane
dioxane.
Al~o eligible are epoxy re~in~ in which the epoxy group~ ar~
attached to hetero atoms of different kind, or ln which s30me or all
of the epoxy group~ are centr~l, for example the N,N,0 trlglyc~dyl
~ 5 -
derlvative of 4-aminophenol, N-glycidyl-N'-(2-glycidyloxypropyl)-
S,S dimethylhydantoin, vinylcyclohexene dioxide, limonene dioxide
and dicyclopentadiene dioxide.
The epoxy re~in~ (a) may be solid or liquid. Preferred epoxy re~ln~
are tho~e having an epoxide content of 1.0 to 5.5.
As component (8~ it i8 preferred to use diglycidyl ether~ or
advanced diglycidyl ethern of dihydric phenol~ or dlhydric aliphatic
C2-C4alcohols, in particular diglycidyl ethers or advanced diglyci-
dyl ether~ of 2,2-bls(4-hydroxyphenyl)propane, 2,2-bi~(3,5~dibromo-
4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)methane, bls(4-hydroxy-
cyclohexyl~methane or 2,2-bis(4-hydroxycyclohexyl)propane; polygly-
cidyl ethers of novolaks 7 or tetraglycidylated 4,4'-diaminodiphenyl-
methane. Most preferred are diglycidyl Qthers or advanccd diglycidyl
ethers of bisphenol A, tetrabromo-bisphenol A or bisphenol F, and,
in particular, polyglycidyl ethers of phenol/formaldehyds or
cresol/formaldehyde novolaks, or mixtures thereof.
Pos3ible ~-arenes Rl and R2 are, in particular, aromatic groups of
6 to 24 carbon atoms or heteroaromatic groups of 3 to 30 carbon
atoms, which groups may be unsubstituted or ~ub~tituted by one or
more identical or dif~erent monovalent radicals such as halogen
atoms, preferably chlorine or bromine atoms, or Cl-Cgalkyl, Cl-Cg-
alkoxy, cyano, C1-Cgalkylthio, C2-C6monocarboxylic acid alkyl ester,
phenyl, C2-Cs~lkanoyl or benzoyl groups. These ~-arene groups may be
mononuclear, condensed polynuclear or non-condensed polynuclear
systems, in which last~mentioned systems the nuclel may be linked
togeth0r direct or through bridge members such as -S- or -0-.
R2 as the anion of a ~-arene may be an anion of 8 ~-arene o f the
aforementioned kind, e.g. ths lndenyl anion, ~nd, in par~icular, ~he
cyclopentadienyl anion, which anions may al80 be unsubstitutQd or
substituted by one or more identical or differeDt monovalent
radicals such as Cl-Cgalkyl, C2-C6monocsrboxylic acld alkyl ester,
cyano, C2-Csalkanoyl or benzoyl group~.
~277~t~0
- h -
Alkyl, alkoxy, alkylthio, ~onocarb~xylic acid alkyl e~ter and
alkanoyl substituent~ may be ~traight chain or branched. Typical
alkyl, alkoxy, alkylthio, ~onocarboxylic acld alkyl eAter or
alkanoyl substituents are: methyl, ethyl, n-propyl, i~opropyl,
n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, methoxy,
ethoxy, n-p~opoxy, iaopropoxy, n-butoxy, n-hexyloxy, n-octylo~y,
methylthio, ethylthio, n-propylthio, isopropylthio, n-butylthio,
n-pentylthio and n-hexylthio, carboxylic acid methyl e~ter, ethyl
ester, n-propyl e~ter, isopropyl e~ter, n-butyl e~ter and n-pentyl
e~ter, acetyl, propionyl, butyryl, and valeroyl. Alkyl, alkoxy,
alkylthio and monoc~rboxylic acid alkyl ester group~ containing 1 to
4 and especially 1 or 2 carbon ato~s in the alkyl moieties snd
alkanoyl groups containing 2 or 3 carbon ato~s are preferred.
Preferred substituted ~-arene~ or anions of substituted ~-arenes are
those containing one or two of the above-mentioned subs~ituents, in
particular chlorine or bromine atoms, methyl, ethyl, methoxy,
ethoxy, cyano~ carboxylic acid methyl or ethyl ester groups and
acetyl groups.
Rl and R2 may be identical or different ~-arenes. Suitable hetero-
aromatic ~-arenes are systems containlng S-, N- and/or 0-atoms.
Heteroaromatic ~-arene~ contsining S- and/or 0-atoms are preferred.
Examples of suitable $-srene3 are: benzene, toluene, xylenes,
ethylbenzene, cumene (i~opropylbenzene), methoxybenzene, ethoxy-
benzene, dimethoxybenzene, p-chlorotoluene, chlorobenzene, bromo-
benzene, dichlorobenzene, acetylbenzene, trimethylbenzene, trime-
thoxybenzene, naphthalens, 1,2-dihydronaphthalene, 1,2,3,4-tetra~
hydronaphthalene, methylnaphthalenes, meehoxynaphthalenes, ethoxy-
naphthalenes, chloronaphthalene~, bromonaphthalene~, biphenyl,
indene, fluorene, phenanthrene, anthracene, 9,10-dihydroanthracene,
triphenylene, pyrene, naphthacene, coronene, thiophene, chromene 9
xanthene, thioxanthene, benzothiophene, naphthothiophene~ thi-
anthrene, diphenylene oxide, diphenylene sulfide, acridine and
carbazole.
~77070
If a i~ 2, then each R2 i8 preferably the anion of a n-arens, snd
each M i9 sn identical metal atom. Examples of anions of subs~ituted
~-arenes are: the anions of met~hyl-, ethyl-, n-propyl- and n-butyl-
cyclopentadiene, the ~nion~ of dimethylcyclopentadiene, oP cyclo-
pentadiene c~rboxylic acid me~hyl ~nd e~hyl ester, and o~ acety~
cyclopentadlene, propionylcyclopentadiene, cyanocyclopents~diene and
benzoylcyclopentsdiene. Preferred anions are the anion o unsubsti-
tuted in~ene and especially the anion o~ unsubstituted cyclopenta-
diene.
The preferred value of a i8 1, Rl i8 benzene, toluene, xylene,
cumene, methoxybenzene, chlorobenzene, p-chlorotoluene, naphthalene,
methylnaphthalene, chloronaphthalene, methoxynaphthalene, biphenyl,
indene, pyrene or diphenylene sulfide, and R~ i8 the anion of
cyclopentadisne, scetylcyclopentadiene OT 1ndene, or benzene,
toluene, xylene, trimethylbenzene, naphthalene or ~ethylnaphthalene.
i~ T~2+ Ti3~ Zr~, Zr2+, Zr3+, Hf , Hf , Hf , Nb ,
Nb , Nb , Cr , Mo , Mo2 , ~ , W , Mn , Mn2 , Ra , Fe2+, Co3+,
Ni2 or Cu2 . Preferably, M i~ a chromium, cobalt, mangsnese,
tungsten or molybdenum cation, especially an iron catioD, most
preferably Fe
Psrticularly preferred complexss of for~uls I are those wherein a i8
1, Rl i9 n6-cumene or n6-2-methylnaphthalene and R2 ~3 the Inion of
nS-cyclopentadiene, n iB preferably 1 or 2, preferably 1 t and q is
preferably 1.
Examplès of suitable metals or non-metals L are Sb, Fe, Sn, Bi, Al,
Ga, In, Ti, Zr, Sc, V, Cr, Mn and Cu; lanthsnides such a~ Ce~ Pr and
Nd, or actinide3, such as Th, Pa, V or Np. Suitable non-~e~als sre
especially B, P and As. Prefarably L is P, As, B or Sb, with P bsing
~ost preferred.
Example~ of complex snions ~LQ~ q are BF4 , PF6 , AsF6 , SbF6 ,
FeCl4 , SnCl62 , SbCl6 , BiCl6 ~ The mos~ preferred complex anion~
are SbF6 ~ BF4 1 AsF6 and 9 in particular PF6 -
~, .
7C)7~3
-- 8 --
Examples of compounds of formula I are: (n6~toluene)(nS-lndenyl)-
iron(II) hexafluorophosphate, (n6-Pyrene)(nS-cYclopontadienyl)-
iron(II) hexaEluoroantimonate, (n6-toluene)(nS-cyclopentadlenyl)-
iron(II) hexafluorophosphate, (n6-naphthalene)(~5-cyclopent2dien-
yl)iron(II) hexafluoroarsenate, ~n6-2-methylnaphthalene)("S~cyclo--
pentadienyl)iron(II) hexafluorophosphate, (n6-cumene)(nS-cyclopenta-
d1enyl)iron(II) hexafluorophosphate and (n6-benzene)(nS-cyclopenta-
dienyl)cobalt(III) bis(tetrafluoroborate).Such metallocene salts and
the preparation thereof are de~cribed e.g. in European patent
application 094 915 A2. Preferred compounds of formula I sre
(n6-2-methylnaphthalene)(ns-cyclopentadienyl)iron(II) hexafluoro-
phosphate and (n6-cumene)(n5-cyclopentadienyl)iron(II) hexafluoro-
phosphate.
By appropriate choice of fillers it is possiblQ to influence the
electrical, thermal and/or optical properties of the epoxy rs~in
sy~tems, for example the electrically or thermally conductive or
insulating properties, the ferroQlectric or ferromagnetic proper-
ties, the piezoelectric, electrochromic or luminiscent propertles.
Photocursble resin compositions are thereby obtained which, after
curing and development, give relief structures or image~ which find
utility especislly in the fields of high-frequency engineering,
electronics, microelectronics and optoelectronics, for example a~
active components in resistors, capacitors, transformer~, inductors~
magnets, memory and display materials, as passive cDmponents in
~lectricsl and thermsl insulators, heat extraction systems or
electromagnetic shields, or also as so-called interconnec~ions, e.g.
in printed conductors or in chip contacting, as well ~B in mounting
chips on the baDe plste~ of their assembly frames.
Suitable metal-con~sining fillers or fillers wi~h ~emiconductor
propertie~ are, in particular~ metals, metal compound~ and alloyD in
which the ~etal is one of Periodic Groups IIa, IlIa, IVa, Ib, Vb9
~'77070
g
VIb and/or VIII. Depending on the desired propertie3 or on the field
of u~e of the epoxy resin compositions of this lnventlon, the
following fillers may for example be used:
1. Electrically conductive fillers of organic or inorganic nature,
e.g. carbon black snd graphite or metal~ of Periodic Group~ Vb, V~b,
VIII and Ib, ~lloys and ~alts thereo~ ~uch 8~ hnlide~, ~xide~ and
~ulfides.
Examples of suitable metals and metal compounds are: vanadium,
niobium, tantalum, molybdenum, tungsten, copper, noble metals auch
as Pt, Pd, Ag snd Au, AgPd alloy3, ~ilver oxide, silver iodide,
copper(II) sulfidet copper(I) iodide, copper(II) o~ide, gold(III)
bromide, iodide and nxide, molybdenum(IV~ ~ulfide, niobium(IV)
chloride and niobium(IV) oxide, palladium iodide, pallsdium oxlde,
platinum(IV) bomide and platinum(IV) chloride, vanadium(III)
chloride, vanadium(IV) oxide, tungsten(VI) chloride and tungsten(VI)
oxide. Preferred metals are silver, copper, silver/palladium alloys,
palladium, platinum, gold, ~ungsten and molybdenum. Particularly
preferred metals are Au, Pt, AgPd, with Ag and Cu powder being most
preferred.
2. Thermally conductive fillers or dielectric substances such as
alumini~m oxide, beryllium oxide, lithium aluminium oxide and
si~icon carbide.
3. Fillers which influence the ferroelectric, $erromagnetic,
piezoèlectric, electrochromic and/or optical properties of the epoxy
resin compositions, for example:
- Ferroelectric substances, e.g. barium titanate, lead titanate,
lead zirconate, NaNbO3, KNbO3, AgNb03 and W03, ~hich are used, inter
alia, for semiconductor~, condenser~ and in display and data
memories in optoeIectronics. Barlum titanate, lead titanate snd lead
zirconate csn al80 be u~ed for imparting piezoelectric propertie~,
e.g. in high-frequency engineering. Tung~t-n, however, also ha~3
~77~7()
-- 10 --
electrochromlc properties and i9 therefore used e.g. in dlgltal
di~plays and in electrography. Preferred ferroelectric ~ubstances or
electrochromic fillers are barium titsnate, lead titanate, lead
circonate and W03.
- Ferromagnetic substQnces ~nd ferrltes of th~ general compo~ltion
MI FezIIIO4 or MIIO~Fe203, whereln MII is a divalent metal ~uch as
Zn, Cd, Co, Ni, Hn, Fe, Cu, Ba, Sr or Mg. Representatlve examples of
preferred ferromagnetic substance~ and ferrites are Fe304, NlFe204,
CoFe20l, and the manganese~zinc ferrites known under the registeret
trademark Ferroxcube~ such as Ferroxcube 4C49 3D3, 3B9, 3B7 and 3C8.
Ferromagnetic substances and ferrites are used e.g. as pe~manent
magnets (MII ~ e.g. Ba or Sr) for transformer~, inductors, insu-
lators, sound recording systems, farrite aerials, magnetic ampli~
fiers or in ferrite cores, e.g. for core memories in elactronlc data
processing systems.
- Phosphore3cent fillers and phosphor3 with luminescent proper~ies,
for exampla CdS, GdZnSI SrS, MgS, CaS and, in particular, ZnS. Such
materisls are used in particular for electro-optical displays.
To achieve the desired, preferably isotropic, physical effect, the
filler~ muBt be u3ed in finely partieulate For~. They are preferably
in very finely particulate form, in particular as 6pherlcal or
rod-shaped, e.g. dendritic or la~ellar, particles. The flverage
particle size of spherical particles i9 advantageously from 0.1 to
20 ~m ~micrometers), preferably from about 0.2 to 5 ~m. Rod-shapad
particies, e~pecially dendritic amd lamellar particles, are preferab-
ly ~.3 to 20 ~m in length and have a layer thickness of 0.1 to 1 ~m.
Compositions of this invention intended for applicstlon to ceramic
substrates additionally contain a flux material (d), preferably in
an amount of 5-5G% by weight, preferably of 10-40% by weight, ba~ed
on the total weight of the compo~ition. Suitable $1ux ~ateri~l ara
s.g. quartz powder~ and, in particulsr, glass powders, ~uch as
~'77~70
-- 11
lead/borosilicate powder, borosilicate powder and blsmuth/lead
silicate powder. Preferred glsss powders sre those having a refrac-
tlve index below 1.8 and A particle ~ize ln the range from 2-50 ~m.
Component (a) ifi preEerably used in sn amount of 5-40% by weight,
whereas the photoinitiator (b) is preferably u~ed ln an amount o~
0.3-4% by weight. The filler (c) ia convenien~ly u~ed in an amount
o~ 30-85% by weight, but the amount of filler lc) and flux material
~d) should normally not exceed 95% by weigh~, based on the total
weight of the composition.
Particularly preferred comnpositions are those contalning:
i) a polyglycidyl ether of a phenol/formaldehyde or cresol/formalde
hyde novolak, silver powder, glsss powder and (n~-2-methylnaphthal-
ene)(ns-cyclopentadienyl~iron(II~ hexafluorophosphate or ("6-cu-
Mene)(ns-cyclopentadienyl~iron(II) hexafluorophosphate as photoinit-
iator;
ii) a polyglyridyl ether of a phenol/formaldehyde or cresol/formalde-
hyda novolak, copper powder, glas3 powder and (n6-2-~ethylnaphtha-
lene)(nS cyclopentadienyl)iron(II) hexafluorophosphate, or
iii~ a liquid bisphenol A epoxy resin, silver powder and
(n6-2-methylnaphthalene)(ns-cyclopentadienyl)iron(II~ hexafluoropho~
phate or (n6-cumene)(ns-cyclopentadienyl)iron(II) hexsfluorophos-
phate as photoinitiator.
The compositlons of the present invention may sl~o contain other
known additiver (e~ conventionally employed in the art of photocur-
able ~sterials. Examples of such additives are: pigments, dye~
reinforcing materials such as glass fibres, other fibre materlals,
flame retardants, reactive diluent~ for the epo~y resins, e.g.
phenyl or cresyl glycidyl ethers, butanediol diglycidyl ethers and
hexahydrophthalic acid glycidyl ethers, antistatic agent~, levelling
~X77C)70
- 12 -
agents, mould release agents, adhe~ion promoters, antioxidants,
light stabilisers snd sensitisers for component (b) such as thioxan-
thones, phthalimlde~, coumarins and anthracenes.
If the compositions contain the flux material (d) or fur~her
conventional additive~ (e), then the sum of component~ ~a), (b~,
(c), (d) and/or (e) iB 100 % by weight.
The compositions of this inventlon csn be prepared in a manner known
per 8e by ~ixing the individual components. The are normally applied
in the form of solutions in organic solvent~ to suitable supports
such as plastic aheets, e.g. polyester sheets, metals, metal alloys,
semi metals, semiconductors,, glass plates, ceramlcs, laminates such
8B copper-coated epoxy laminates, sio2 or Si3N14. Examples of
suitable organic solvents are polar solvents, preferably polar
aprotic organic solvents which may be used singly or in mixtures.
Examples of such suitable solvents are: slcohols such as ~ethanol,
ethanol and diacetone alcohol amides of sliphatic monocarboxylic
acids such as N,N-dimethylfor~Amide and N,N-di~ethylscstamide;
ethers such as diethyl ether, di-n-butyl ether, tetrahydrofuran,
dioxane, 2-methoxyethanol, 1,2-dimethoxyethane, diethylene glycol
dimethyl ether, diethylene glycol diethyl ether, diethylene glycol
mono-n-butyl ether, triethylene glycol dimethyl ether; halogenated
hydrocarbons such as methylene chloride, chloroform, carbon tetra-
chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,l,2,2~tetra-
chloroethane; carboxylates and lactones such as propylene carbonate,
ethyl acetate, methyl propionate, ethyl benzoate, l-acetoxy-2-
ethoxyethane, l-acetoxy-2-methoxyethane t r-butyrolac~one and
r-valerolactone sulfoxides such as dlmethylsuloxide and trimethyl-
sulfoxide, sulfone3 such as dimethyl sulfone, diethyl sulfone,
tri~ethylene sulfone snd tetramethylene ~ulfone; ketone~ ~uch as
di~ethyl ketone, methyl ethyl ketone, methyl lsobutyl ketone nnd
cyclohexanone; ~ubstituted benzenee such a~ chlorobenzene and
nitrobenzene. Preferred solvents are carboxylates and ketone~ such
as 2-acetDxy-2-ethoxyethane and cyclohexanone.
~t77~)7~
- 13 -
The ~olutions sre applied by conventlonal methods to the support,
for example by dipping, coating, spraying, padding, centrifuging or
by roller coating.
The compositiona of this invention can al80 be applied in the dry
state, e.g. by powder coating. Depending on the utility, the dry
layer thicknesses sre generally in the range from about 0.5 to 200
~m, preferably from 5 to 100 ~m. After coating, any residual solvent
is removed in conventional manner, e.g. by heating and, lf desired,
additionally under vscuum.
It i~ al80 po~sible to apply films obtained with the composition~ of
this invention to other substrates before further treatment. Thus,
for example, films obtained on pl~tic sheets can be applied, after
drying, with a roll laminator to other ~ubstrates such aR glas~ or
ceramic plstes, Monel~ ~3ubstrates (nickel/copper alloys~ and Tombak
substraees (copper/zinc alloys), e.g. silver-coated or gold-coated
Tombak and Monel substrates.
Curing of the composition~ and the coatings obtained there~ith can
be carried out in one step by photocuring, preferably at ~levated
temperature, e.g. in the range from 80 to 130C. Howe~er, curing i~
conveniently carried out in two steps, i.e. by photocuring followed
by a thermal postcuring. Photocusing can be carried out with visible
l~ght as well as with U~ light having a wavelength of 200~600 nm and
at an intensity of 150-8000 watt~, preferably of 1000-5000 watts.
Suitable light source3 are e.g. xenon lamps, argon lamps, tung~ten
lamps, carbon src3, metal halide and metal arc lamps ~uch a8
low-pressure, medium-pressure and high-prsssure mercury lsmps, argon
ion lasers, frequency d~ubled Nd-YAG lasers (yttrium/aluminlum
garnet) ~nd W lasers. It i~ preferred to effect irradiation with
vi~ible light (VIS) or VIS lasers.
* ~lrQ ~ kt~k~
~L2~07C~
- 14 -
Tha irr~diation time depend~ on a number oE factors, e.g. on the
thickness of the composltion, the nature of the llght Dource and its
dlstance from the layer to be irrsdiated. The irradiatlon time is
normally from 1 second to 600 ~econds.
The thermal aftertreatment (po~tcurlng? i~ conveniently 0Ef0cted in
the temperature range from 50 to 150C, preferably from 60 to
130C.
After exposure and the optional additlonal thQrmal curi~g, the
unexposed image srea~ are developed with a solvent or mixture of
solvents. Sui~able ~olvents are for example tho~e of the kind cited
above. Preferred solvents for developing are cyclohexanone and
mixtures of propylene carbonate, diethylene glycol mono-n-butyl
ether and r-butyrolactone.
Coating~ obtained wlth compositions containing electrically conduct-
ive or dielectric fillers and flux materials are particularly
Auitable for applications to ceramic, e.g. for thick-layer circuit~
on ceramic substrates or contacts on cera~ic substrates for lnte-
grat~d circuits (chips).
After curing, the coatings are conveniently baked at elevated
teMperature, preferably in the range from 250 to 1000C, most
prefer~bly from 400 to 900C, to give conductive or dielectric
relief structures or images. Baking iB advantageously effected in
air, in an atmosphere of 2, N2 and/or H2. When uslng silver powder
as filler or silver-containing fillers, baking iB preferably
effected in an atmo~phere of 02. If copper powdar or A copper
compound iB UBed aB filler, baking is advantageously carried out
first in 2 and then in Nz or H2 or in A mixture of botb gases.
AB already mentioned, the compositionq of this invention are
suitable for use in various fields of technology, especially in
electronics, microelectronic~ and optoelectronics. Accordingly, th~
707~
- 15 -
invention al80 relates to the u~e of the composition~ for producing
relief structures, iMages or bnnds by photocuring ~nd optional
additional postcuring. Preferred utilities are:
When using electrically conductive filler~:
- for printed conductors on ceramic, enamelled steel plates, poly~er
printed circuit boards or flexible plastic sheets;
- the production of electrodP patterns on aluminium and gla~s for
liquid crystal displays and the like;
- for touch contact3 on flexible plaYtic sheets for keyboards;
- for contact bonds between chips and their supports;
- for bonding acti~e and passlve microelectronic componcnts to
printed circuit boards (made of ceramlc, enamelled steel or
plas~ics);
- for improving dsmaged tracks and contact~ in
electronic systems, components and modules.
When using dielectric fillers:
- for insulating ad~acent or converging tracks on ceramic, enamelled
steel and plastic ~ubstrates;
- for protecting layers as coverings for electronic and m~croel~
ectronic circuit components, contacts and tracks.
When using thermally conductive fillers:
- for heat extraction sy~tems in high-performance and high-frequency
electronics.
When using ferroelectric fillers:
- for producing pressure-sensitive and sound-sensitive sensors Dn
the basis of pie20electric effect~;
- for making optoelectronic display element~.
When using electrochromlc filler~:
- for making electrochromic display element~.
~77C~70
- 16 -
When uaing phosphoresc~nt fillers or phosphor~:
- for making flnely structured cathode ray tube display~
- for applying luminescent markings to masks for photographic or
lithographlc purposes and to variou~ articles, shield~ and
surfaces for informatlon, safety and decorative purpose~,
A particulsrly preferred utility of the compo~itions of thi~
invention (with flux material~ i9 the productlon of thick layer
circuit~.
In the following Examples, parts and percentages are by weight
unless otherwise indicated.
Example l: To ~ parts of a 45% solution of an epoxy/cresol/novolak
resin (mol wt c. 1270, epoxide eq. wt. 238 g/eq., epoxide content
4.2 eq./kg) in cyclohexanone are added lO parts of silver powder
~precipitated, average particle size 10 ~m, ex Fluka), S parts o a
TiO2 gla~ powder ~hcmogeneou~ white powdes mix 20-6000, ex Draken-
feld) and 0.18 part of (n6-2-methYlnaphthalene)(nS-cYclopenta-
dienyl)iron(II) hexAfluorophosphate. The mixture i8 dispersed for 10
minutes in an ultrasonic3 bath and applied with a 50 ~m doctor knife
to a 3 mm Pyrex~ glass plate. Through a photomask which reproduces a
typical pattern of a printed circuit, a conductive pattern of a
printed circuit that still has slight conductivity (<10 6 oh~ l-cml)
i8 obtained by exposure for 5 minute3 to the rAdiation of a 1000
watt halogen lamp, curlng for 20 minutes at 80C and sub~equent
development in ~yclohexanone in an ultrasonics bath. Tracks with a
specific conductivity of 4.9 x 104 ohm l~cm 1 are obtained by
subJecting the printed circuit so obtained to a heat treatment for 5
minutes at 650C in air.
Example 2: To 6.75 parta of a 60% solution of the epoxyJnovolak
resin described in Exa~ple 1 in l-acetoxy 2-ethoxyethane are added
10 part~ of silver powder (average particle aize 2-3.5 ~, ex
Ventron) and 5 part~ of a glass powder tLow Expansion Glsas Frit E
;~ , ~E ~ ARtc
~,2770~o
- 17 -
1980~, ex Drakenfeld). The mixture is dil~ted wi~h 1.25 partn of
1-acetoxy-2-ethoxyethane and ground for 15 hours in a ball mill with
4 mm glass beads. Then a solution of 0.18 part of (~6-2-methylnsphthal-
ne)(ns-cyclopentadienyl)iron(II) hexafluoropho3phate di~solved in
0.5 part of N,N-dimethylformamide and 0.5 part of 1-acetoxy-Z-
ethoxyethane is added. A film of the composition ao obtained is
applied wlth a 50 ~m doctor knife to a polyethylene terephthslate
sheet and dried for 10 minutes at 80C. This film is then trans-
ferred at 130C with a roll laminator to an Al203/ceramic plate
(Rubalith~ substrate for thick film coatings, ex Rosenthal Techn~k
AG).
Through a photomask which reproduces a typical pattern of a prlnted
circuit, a 12-~tep Stouffer wedge and an ITEK bar pattern mask for
determining the resolution, the film i~ exposed for 5 minutes to the
radiation of a 1000 watt halogen lamp, cured for 5 minutes at 110C
and developed in a devPloping bath consisting of 50 partæ of
propylene carbonate, 30 parts of diethylene glycol mono-n-butyl
ether and 210 parts of ~-butyrolsctone, to give the conducti~e
pattern of the printed circuit as well as cl~arly resolved lines of
the bar pattern havlng a width of 50 ~m. The conductive image is
baked for 80 minute~ at 800C in a retort furnace. The track~
subsequently have a surface resi~tance of 20 mohm ~thickness o~ the
layer: 8 ~m). Last completely reproduced step on the 12-step
Stouffer wedge after baking: step 8 (known to be a referencQ
standard for the light-3ensitivity).
Conductive psttern~ with comparably good properties are obtained by
using corre~ponding amount~ of (n6-cumene)(nS-cyclopentadienyl)-
iron(II) hexafluorophosphate instead of (n6 2-methylnaphthal-
ene)(n~-cyclopentadienyl~iron(II) hexsfluorophoæphate in E~ample~ 1
and 2.
Example 3: A copper-coated epoxy laminate (gla3~-reinforced epoxy
printed circuit board) is coated with the composition descrlbed in
Example 1 with the aid of a 50 ~m doctor knife and the coating i~
RA~E~A~CS
~L2~7070
- 18 -
dried for 15 ~inutes at 80C~ On exposure to radiation ~i~h the
514 nm line oE an argon ion laser (Innova 90~, ex Coherent), an
energy of 270 mJ/cm2 suffices to develop a conductive pattern after
a 5 minute cure at 110C.
Examnple 4: 3 parts oE a 45% solution in cyclohexanone of the
epoxy/novolak resin described in Example 1 and 12 parts of copper
powder (spherical, 325 mesh, ex Ventron), 2 g o~ a TiO2/glass powder
(Homogeneous White Powder Mix 20-6000, ex Drakenfeld) and 0.06 part
oE (~6-2-methylnaphthalene)(ns-cyclopentadienyl)iron(II) hexafluoro-
phosphate are processed as described in Example 1. Likewise as
described in Example l, Pyrex~ plates are coated with this mixture
and the coating is irradiated and developed. The conductive patterns
are su'osequently treated with air for lO minutes at 500C in a
retort furnace, heated for 5 minutes under nitrogen to 750C and
exposed for 10 minutes at 750C to a flow of hydrogen (10 ml/min).
The tracks have a surface resistance of 6 m-ohm (layer thickness:
8 ~m~.
Example 5: 25 parts of copper powder (avera~e particle size 10 ~m,
ex Ventron, washed for 10 minutes in a 2N HNO3 solution, filtered
and dried for 1 hour at 80C/13332 Pa) and 0.6 part of (~6-2-methyl-
naphthalne)(n5-cyclopentadienyl)iron(II~ hexafluorophosphate are
added to 30 parts of a 45% solution in cyclohexanone of the epoxy
novolak resin described in Example 1. The ~ixture is dispersed for
10 minutes in an ultrasonics bath and applied with a 150 ~m doctor
knife to a polyester sheet (MELINE~, ex ICI). The film is dried for
20 minutes at 75C to give a dry film of 60 ~m. This film is exposed
for 3 minutes to the radiation of a 1000 watt halogen lamp at 20~C
through a photomask representing the pattern of a four-point
measurement for conductivity measuring 5 x 0.5 mm. The film is then
cured for 20 minutes at 80C and subsequently developed with
cyclohexanone for 30 seconds in an ultrasonics bath, affording a
pattern for the 4-point measurement of conductivity with a specific
conductivity of 43 ohm cm 1.
.,,. ~
~77~
- 19 -
Exsmple 6: The proced~re of Ex~mple 5 is rep~ated, u~ing 40 g of a
zinc ~ulfide phosphor ~LInMINEX G~, luminescent mlxture ex Riedel-D~
Haen) in~tesd of copper powder. Images which luminesc~ in the dark
sfter 10 minutes are obtained.
Exampls 7: 1.5 parta of silvsr powdsr (average particle size 2-3.5
~m, ex Ventron) and 0.06 part of (~6-2-methylnaphthalene)(~5-cyclo-
pentadienyl)iron(II) hexafluorophosphats are addsd to 3 part~ of a
45% solution in cyclohexanone of the epoxylnovolak rssin described
in Example 1. Ths mixture is di~persed for 10 minutes in an ultrason
ic~ bath and a film of thi~ mixturs is applied with a 100 ~m doctor
knifs to a polysthylsne terephthalats ~heet and then dried Por 10
minute~ at 80C. A piece of this film msssuring 0.2 x 0.3 cm i8
transferred at 130C to the silvsred base plats of a DIL (Dual-in-
Line) a~ssmbly frams, exposed for 60 seconds to ths radistion of a
5000 watt halogen lamp and thsn bondsd to a 0.2 x 0.3 cm ~ilicon
crystal at 120C over 2 minutes by fixing ths ~andwich coDsisting of
assembly frame/silver-containing epoxy resin film/~ilicon cry~tal
with clips betesn two plates. Ths ~ilicon crystal ~ub3equently ha~ a
bonding strength of 10 N/~m2 on the ~ilvered a3sembly frame ldet~r-
mined by the bonding ~trength test of E. Ludsr: ~8U hybridsr
Mikro~chaltungen, page 42, Springsr Verlag, Berlin (1977)1.
Example 8: 1 part of 3ilver powdsr (~ilvsr flakes havlng an average
psrt~cle si~e of 3 x 10 ~m, sx Ventron~ snd 0.06 part of (n6-2-~e-
thylnaphthalsne)(ns-cyclopsntsdisnyl)iron(II) hexa~luorophohosphate
srs added to 2 parts of a liquid bisphenol A spoxy resin lbi~phenol
A diglycidl ether mixed with 2 % by weight o~ cresyl glycidyl ether;
epoxids content 5.31 eqlkg~ and the mlxture i8 di~per~ed for 10
minutss in sn ultrssonlc~ bsth. Thsn 0.2 part of thi~ mixtura i~
applied to the silvsred ba~e plsts of a DIL assembly frame. The
mixture i~ sxposed or 300 ~scond~ to the rsdiation of a 5000 watt
hslogen lamp and ths assembly fr~me i~ bonded to a 0.2 x 0.3 silicon
cry~tal by h~ating for 5 minutes to 130C. According to the bonding
strength test described in Exampls 7~ the 8ilicon cry~tal ha~ a
bonding strsngth of 10 N/~m2. To dst~rmins the ~olum~ resi~tivity
7~0~70
- 20 -
an analogou6 formulation iB prepared with a 0.06 cm copper plate
measurlng 0.2 x 0.3 cm. A ~imple two-point measurement gives a
volume resistlvity of 70 m-ohm (thickness of the adhesiva layer c.
10 ~m). Compar~bly good re~ults are obtained by using a corre~pond-
ing amount of (n~-cumene)~ns-cyclopentadienyl)iron(II) hexafluoro-
pho~phate in thi~ Example instead of (n6-2-methylnaphthalane)(nS-
cyclopentadienyl)iron(II) hexafluoropho~pha~e.
