CA1143207A - Dry film photoresist including an intermediate uv transparent, polymeric layer and a photopolymerizable layer - Google Patents

Abstract

Abstract A dry film photoresist consisting of a two-layer base incorporating a solid polymeric substrate with a thickness of from 15 to 100 µ and an intermediate polymeric layer with a thickness of from 3 to 15 µ transparent to UV-radia-tion within the range of from 300 to 400 nm, a light-sensitive layer with a thickness of from 4 to 20 µ and a protective polymeric film with a thickness of from 5 to 50 µ. All the four of these layers are bonded therebetween by adhesion forces so that the adhesion of the protective polymeric film to the light-sensitive layer is less than the cohesion strength of the light-sensitive layer; the adhesion of the solid polymeric substrate to the intermediate polymeric layer is less than the adhesion of the intermediate polymeric layer to the light-sensitive layer and the adhesion force of each of the three above-mentioned layers is less than the cohesion strength of each of said layers.
The dry film photoresist according to the present inven-tion possesses a high resolving power (minimal reproducible line of from 5 to 50 µ) and it is warping-resistant in both manufacture and use.

Description

DRY FILM PHO~ORESIS~

The p~esent invention relates to materials for printing circuit boards and, more specifically, to dry film photore-sists.
These dry photoresists are useful in t~e manufacture of printed circuit boards and other articles with a sophisticat-ed pattern of conductors, including hyb~id integrating cir-cuit~. .
Known in the art are dry film photoresists comprising flexible laminar systems incorporating a solid polymeric base (substrate) - usually polyethyleneterephthalate with a thickness of 20-25~u, an adhesive ~especially upon heating) light-sensi-tive layer with a thickness of essentially 18-100 J~ and a pro-:~ective polymeric film (generally polyethylene film) preventing the light-sensitive layer from dust and sticking when reeled (cf. British Patent ~o. 1,361~298 Cl. C3G2, published July 1974;
US Patent No. 3,873,319 Cl. 96-87R, published March 25, 1975).
One of the prior dry film photoresists comprises a flexible laminar system incorporating a solid polymeric polyehtylenetere-phthalate substrate with a thickness of from 5 to 100 Ju, a light-sensitive layer with a thickness of from 5 to 1,000 ~
containing a light-sensitive compound capable of forming free radicals upon e~posure to W -light ethyl ether of benzoin, a saturated compound containing in its molecule ethylene-type C=G~ bonds - dimethacrylate(bis-ethylene glycol)phthalate and a product of addition of methacrylic acid to epo~y resin based on 4,4'-dihydroxy-2,2-diphenylpropane and a polymer which ~,.,-- ~
i~

.
`

. . .

:-~1~32~37 .~
is a film-forming component of the light-sensitive layer - a co-polymer of styrene with monoisobutyl ether of ~umaric acid (50:50 mol.%), and a protective polymer film with a thicknes8 of from 5 to 100 JU being over the light-sensi~ive layer so that t~e adhesion of the protective film to the light-sensitive layer : is smaller t~a~ the adhesion of the solid polymer substrate (polyethyleneterephthalate film~ to the light-sensitive layer;
adhesion ~alues of the la~ers are inferior to the cohesio~
values of these la~er~ thu~ pro~iding the possibility of a successive stripping-off first of the protective film and then the solid polymer substrate from the light-sensitive layer.
The light-sensitive layer may also incorporate a dye-stuff such as "methyl violet", a radical-polymerization inhibi-tor such as hydroquinone, a plastifying agent such as glycerol-1,3-dipropionate (cf. British Patent No. 1,549,952 Cl. G 03 C
1/68 1/71//C 08 ~ 2/50, published August 8, 1979).
Resolution of dry film photoresists depends, to a con-siderable extent, on the thickness of their transparent poly-meric base (substrate) which separates the photographic tem-plate from the li~ht-sensitive layer upon exposure. ~hen a thinner base is used, the pattern of the protective relief is less distorted and resolving power of a dry film photoresist is increased.
However, the use of a film base with a thic~ness of below 20 ~ in the manufacture of the prior art photoresist causes difficulties associated with casting of the light-sensitive ~ ' layer and drying thereo~ due to a low mechanical strength of thin films and possibilities of their warping especially in-side the hot section of the drying chamber of a casting machine, as well as upon the application of the photoresist onto board blanks thus causing undergrade qualit~ o* the resulting article~.
~hus, upon casting of the light-sensitive layer onto a polyethy-leneterephthalate film with the thickness of 10 JU the pol~-meric substrate warping as high as 5 mm is observed. ~he differ-ence in thickness o* the light-sensitive layer in this case may be as high as 30 to 50~ and over. During the application of such a photoresist onto board blanks by means of a roller-type laminator folds are formed which break the integrity of the light-sensitive la~er due to a strong deformation of the base.
~or this reason the prior art photoresists have a thicker base (20-25 JU and above) thus ensuring a lesser warping in the manu*acture and use of photoresists.
Therefore, the above-mentioned limitations substantiall~
restrict the field o* applicatio ~ f known dry film photoresists.
It is an object o* the present invention to provide such a dry film photoresist which would have a high resolving power ~minimally reproducible line o* 5 to 40 ~) and be warping-resistant in the manufacture and use.
This and other obJects of the present invention are accomplished by a dry *ilm photoresist comprising a flexible laminated system incorporating a solid polymer substrate with a thickness of from 15 to 100 p, a light-sensitive layer with ,.

. ' ' .

~ 1i432~7 . .

a thickness of from 4 to 20 )u containlng at least one light-sensitive compound capable of froming free radicals upon exposure to W -light, at least o~e unsaturated compound con-taining in its molecule ethylene-type ~C=C~ bonds and at least one polymer which is a film-forming component of the light-sensitive layer; and a protective polymer film with a thickness of from 5 to 50 ~ placed over the light-sensitive layer, wherein in accordance with the present invention between said solid polymeric substrate and the light-sensitive layer there is interposed an intermediate polymeric layer transparent .
to W -light within the range of from 300 to 400 nm and having thickness of from 3 to 15 ~ consisting of a polymer alcohol, or polymer ester, or polyamide, or a halogenate~i polymer, or polyacrylonitrile, or a mixture thereof; all the ~our above-mentioned layers are bonded therebetween by means of adhesion forces so that the adhesion o~ the protective polymeric film to the light-sensitive layer is less than the cohesion strength of the light-sens~ive la~er and the adhesion of the solid polymeric substr~te to the intermediate layer is less than the adhesion of the intermediate layer to the light-sensitive layer, while the adhesion of each of the above-mentioned three la~ers is less than the cohesion strength of each of these layers.
It is advisable that as the polymeric alcohol the above-mentioned intermediate layer of the dr~ film photoresist ac-cording to the present invention contain water-soluble methyl-cellulose or polyvinylulcohol.

, 11~3207 ,.

It is also advisable that as the polymeric ester the intermediate polymeric layer of the dr~ film photoresist according to the present invention contain cellulose triace-tate or polyethyleneterephthalate.
It is desirable that as the polyamide the intermediate polymeric layer of the dry film photoresist according to the present in~ention contain polyhexamethyleneadipamide or ~e-latine.
It is also desirable that as the halogenated polymer the intermediate polymeric la~er of the dry film photoresist ac-cording to the present invention contain a copolymer of tetra-fluoroethylene or trifluorochloro~thylene with vinylidene fluoride.
It is preferable that as the polyacrylonitrile the in-termediate polymeric layer of the dry ~ilm photoresist accord-ing to the present in~ention contain a polymer of acrylic acid nitrile.
Among other possible embodiments it should be noted that the intermediate polymeric layer can also incorporate dyestuffs in an amount of from 0.01 to 1.0% by weight of the intermediate polymeric layer.
As the dyestuff it is advisable to use rhodamine GG ~G), C.I. No. 45160 (752).
It is also advisable that the intermediate polymeric layer of the dry film photoresist according to the present invention contain a plastifying agenb in an amount of from 5 to 15% b~
weight of the intermediate polymeric layer.

, 1~3Z~7 As the plastifying agent in said intermediate pol~me-ric layer of the dry film photoresist use may be made of hydroxyethylated dodacylpbenol.
It is desirable that tbe intermediate pDlgmeric layer o~
t~e drg film photoresist accoiding to tbe present inventi also contain suriactants in an amount of from 0.1 to 0.5%
by weight of said intermediate polgmeric layer.
As tha surfactant in the intermediate polymeric layer of the dry film p~DtDre~ist it is desirable tD use a sodium 9alt of dibutylnaphthfllene sulphonic acid.
The dry film photDrasist according to the pres~nt invea-tion makes it possible ~o obtain a resolving pDwer sufficient tD produce cDhductors of printed circuit board~ with a thick-ness Df frDm 5 tD 50J~ , the photoresist is warping-resis-.
tant to deformatiDns Df the substrate and ths light-sensit~ve layer in the manufacturs and use thereof.
The dry film p~Dtoresist according tD the present i~-VentiDn i9 prDduced in the following prsfsrred manner.
Onto the surface of a solid polymeric substrate - film made of regener~ted cellulose (cellophnne), polyethylene-terephthalate, polgamides 9uch as polg-m-phengleneisophthal-amide (pheuglone), polyamides such as polypyromellitimide, cellulDse triacetate or other film matsrials possassing ade-quately high cDhesion stren~th and having thickness of from 15 to 100 ~ tbere is applied, bg casting, a 5 to 20% 901u-1~32(:~7 tio~ of a polgmor transpare~t to UV-rediation within the ra~ge of frDm 300 to 400 nm, a polymerlc alcohol such as a solution o~ polyvinyl alcDhol with a cDntent of the residual acetate groups of from 3 to 20 mol.%, methglcellulose with a substitution degrre of 1.25 tD 1.6, a balogenated polymer such as a copDlgmer of vin~lidene fluoride wit~ tetrafluoro-ethylene, a cDpolymer ~f vinyliden flu~rids with hexafluors-prDpylene, a cDpolymer of vingliden fluoride with trifluoro-chlorDethyle~e, a pDlyamide? i.e. a pDlymer with its molecule containing a radical- N~-C0-, phDtographic gelatine, polg-hexamethgleneadipamide, polg- ~ -caproamide, a mixed polg-amide (50 : 50 mol.%) ~pDl~hexameth~lene(adip/sebac)amide, a polymeric 6ster sucb as ccllulose scetates, polyethgle~e-terephthalate, polgacrylonitrile such as a pDlymer of acrylic acid nitrile, Dr mixtures thereDf. In addition, the polymer solution can also contain dyestiffs such as rhDdamin GG
(G?, basic blue "~" (C.I. No. 44040), methyl violet (C.I.
No. 42535) in an amount of from 0.01 to 1.0% bg weight Df the intermediate polymeric layer, plastifying agents such as hgdroxgethglated dodecglphenol with the molecular wei~ht Df 500 units in a~ amount Df from 5 to 15% by weight Df the polymsr and sur~actants suc~ as disodium salt ~f dibutyl-naphthalenesulphDnic acid in an amDunt of from 0.1 to 0.5%
b~ weight of the polymer. The cast layer is dried at a tempera -ture wit~in the range of from 30 to 120C for a perlod offrom 0.5 to 5 minutes. Tbereafter, Dnto the suriace of tbe dried intermediate polymeric layer with a tbic~ness of from to 15 ~ there is cast a 10-40% solution containing at least one light-sensiti~e cDmpound capable of forming free radicals upon exposure to UV-radistion such as arDmatic ke-tones, aromatic diketones, polynucleous quinones: 4,4'-bis (diethylami~)benzopbenone, fluorenone, 2-tert.butylanthraqui-none, benzoin metbglate, ~ichler ketone; at lesst one unsaturat-ed compound containing in its molecule ethylene-liEe ~ C=C_ bonds such as acr~lic esters-of polyhydric alcDbola, unsa-turated amides: pentaerythritoltriacrylate, triethyleneglycol dimethacrylate, pentaerythritoltetraacrylate, trimethylolp~ro-pane triacrglate, methacrylamide, acrylamide; at least one polgmer comprising a film-forming component of tbe light-sen-sitive layer; the polymer can simultaneously act as said ligbt-sensitive compound snd~or unsaturated cDmpound, for example, polymethylmethacrylate, a copolymer of styrene with mono-n-butylfumarate, a copolymer of styrene with m~noisoam~l-maleate, methacrylated resin based on 2,2-bis~4~-hgdroxyphe-nyl)prDpane with the molecular weight of 600 units, a product of interaction of epoxy resin based on 2,2-bis(4'-h~droxyphengl)-propane with acrylic anhydride (molecular wsight of 1,500 units), a product o~ in~eraction of epoxg resin based on

2,2-bis (4'-hydroxgpbenyl)- propane with p-benzoylbenzoic acid i~43ZV7 g and acrylic anb~dride (mDlecular wei~bt of 1,650 units, the co~tent of combined p-benzD~lbenzoic acid Df 5.Z~ b~ weight), a product of chemical edditiDn of p-benzoylbe~zoic acid tD
epDxy rosin basod on 2,2-bis-(4'-hydrox~phe~l)propane (mcle-cular woight 1~200 units, the contont of combi~ed p-benzw~l-benzDic acid is 20.1% by weight). FurtbermDre, bhe ~olutio~
.
Df the light-sensitivo co~position can incorpDrate d~es$uffs such as methyl YiDlet, cr~stalline violet, basio blue "~" in an amount of from 0.1 to 5.0% bg weight Qf tbe polymer; in-bibitDrs ~f radical pDl~merization such as phenolss h~dro-qui~D~e, p-metbox~phenol, in au amount of from 0.01 to 5.0% b~
weight of the polymer; plastifying agents such ~s triethyleno-glycol diacetate.
~ be tbus-formed light-sensitive la~er is dried 8t a tem-perature witbin the range of usuall~ from 20 tD 150C for 0.5 tD 5 mlnutes by air-blDwing.
Tbcn onto tbe light-sensitive layer with a tbickne~s of frDm 4 to 20 r there is applled by means Df, fDr oxample a rubber-coated roller, a protective pol~meric film with a thick-ne~s of 5 to 50~ made of, fvr example, pol~ethylen~, po-lgp~opyleh~, pol~isobutylene, polytetrafluoroethylene and other film-forming p31ymers.
Ther~foro, the re~ulting dry film photoresist comprises s flexible fDur-lager s~stem, wheroin all the four layers are bonded tberobetwoe~ b~ adhesion forces 90 that tbe adha-. . ~ , .

sion of tbe prDtective polymer to the light-sensiti~e layer i9 1eS9 than the cobesion strength of tbe ligbt-s~nsitiva layer and tbe adbesion Df the sDlid polymer substrate to the intermediate polymeric layer is less tban the adhesion of the intermediate layer to the light-sensitive layer while the adherence of each of said three layers being less than thc cohesion strength of each of these layers.
The dry film pbotoresist possesses a high resolving power (mini~ally reproducible line of 5 to 50J~ ) and, owing to the presenca ~f a twD-la~er substrate with a thickness of frDm 27 tD 108JM cDnsisting of a solid polymeric substrate and an intermediate polymeric layer, it is substantiall~
more resistant to warping both in the manufacture and use.
The mode of application o~ the dry film photoresist according tD the present i~vention c~nsists in the following.
Prior to tbe deposition of th~ dry film photoresist ~nto the substrate , the protective pDlymeric film is removed (stripp~d-off) in a mechanical wa~ en onto a substrate made Df a metal such as copper, silver, nickel, a nonme~al such as sital or a semi-conductor such as germanium, silicon, there is applied, by rolling at a temperature of from 100 to 120C or pressing-on at a temperature of from 50 to 130C, a flexible laminated system containing a solid polymeric substrate with a thickness o~ from 15 to lOOJ~, an intermediate polymeric lager transparent to UV-radiation witbin the range .~ ~

11~32~7 of fr~m 300 to 400 ~m with a tbickness of ~rom 3 tD 15~ and a ligbt-sensitive layer with a thickness Df from 3 tD 40~.
Then the flexible polgmeric substrate is removed (stripped-Dff) from the surface Df the intermediate pol~meric lsyer and a phototemplate is placed onto the surface of tha inter-mediate pul~meric layer containing tbe image to be reproduced;
tbo light sensitive layer is expDsod through tbe ph~totemplate and ths intermdiate layer, the template i5 removed along .. . .
with the intermediate polymeric layer from tbe surface of the li~ht-sensitive lager. The rem~val Df the intermediate poly-meric layer is effected by stripping-off or by dis~olution in an appropriate s~lvent, ur it is effected simultaneously witb the development so that the intermediats polymeric layer i9 dissolved i~ the developer of the light-sensiti~e layer.
After the removal of tha intermediate polym~ric layer the light-sensitive layer is developed in an appropriats de-velDping agent selectively dissDlving the non-egposed area9.
For a better understanding ~f the pre~ent invention, some specific example rillustrating its embodiments are given hereinbelow.
Example 1 A dry ~ilm photoresist incorp3rates a solid substrata of a pol~ethyleneterepbthalate film witb the thickness of 40 r and an intermediate layer, depDsited thereonto, of meth~lcellulose with the degree Df substitutio~ of 1.4 and 32~17 thickness of 8 ~ . Over the layer of metbylcellulose a light-sensitive layer is d~posited whicb has tbe fDllowing composi-tion, g polymethylmethacrylate 100 pentaerythritol triacrglato 70 triethyleneglycol dimethacrylate 15 4,4'-bis(diethylamino) benzophe-nonc 5 - fluorenone 5 dyestuff "meth~l viDlet" 0.25 ~ydrDqui~Dne 0.02.
- A reel of the photoresist is placed i~to a roller-type laminator prDvided with a means for mecha~ical strippi~g-off snd winding of the prDtective pDlyeth~lene film with the thickness of 20JU.. ~he applica~iou of th~ phDtoresist is cDnducted at the temperature of 115~ ~ f the heati~g element~
and the speed Df 1 m/min Dver tbe pre~treated surface ~f a copper foll, Then the pol~meric substrats of the phDtDresist (polyeth~le~eterephthalate film i8 stripped-Dff from the re-qulti~g sample. I~ doing 90~ the intermediate layer consisting of meth~lcelluloso remains on the surface of the light-sensi-tive ls~er. Prior to exposure a phDtographic template i9 place Dver the layer Df msthylcellulose.
For tbe purposo of e~pDsurs use is made of a 1 kW mercury hi~h-pressure lamp. ~he expo~ure time is 40 sec. After ex-11~32~'7 posur0 methylcellulose is washed with water from tbe sur-face of th~ light-sen~itive layer, the latter i9 tben deve-lDped ~n a stream un~t for the peri~d of 60 seconds. Th3 r~sulting prDtective relief well r~prDduc~s the pattern of tbe template. Tbe minimal reproducible line of the tomplate i9 30~ .
A high thickness ~f the base ~48~ for both la~ers;
solid polymeric base and the intermediata laycr) facilitates casting and drying of the light-sensitive layer, as well as application of the phctoresist ontD the substrate, prevents .
thc pDlymeric basa from warping and the light-ssnsitive layer from deformation~ ~he warping of the bass in this csse does not exceed 1.5 mm. ~he prior art dr~ film 2botoresist in-corporatin~ a single-layar pDlyeth~lenctere phthalate base Df the same thickness (48r ) has a substantiall~ lower resol-ving pDwer. The minimal reproducible li~e und~r the same test conditiDns is 150 r .In tbe case of using tbe prior art photoresist havi~g a 9i~gle-la9er base cf metbylcellul~se with the thickness o~ 8 ~ ,warping is as bigh as 6 mm and causes damage cf the ligbt-se~sitive layer due to the formati-o~s of ~olds on tbe pbDtoresist film.
Example 2 A dry film photoresist contains a film base consisting Df a substrate bssed on c~llulose triacetate witb tbe thick-~ess of lOo ~ and an intermadiate la~er based Dn polyvinyl .
`:
,~- , .

. ' - ` , ' 11~3207 alcohol witb the content of the residual acetate groups of 10 mDl.% snd the thickness of 3 ~ . Onto the surface of the lager of polyvinyl alcohol there is applied a light-~ensitive layer ~ith the thickness of 10r having the following com-position9 g:
cDpolymer of styren ~ ith monD-n-butyl-ether of fumaric acid (50 mDl.% of tbe later) 100 pentaerythritol triacrylate 40 pentaerythritol tetraacrylate 20 trimethylolpropane triacrylate 10 methacrylamide 10 2-tert.butyla~thraquinone 12 dyestuff "methgl violet" 0.2 p-methDxyphenol 0.01.
Prior to the application Df the photoresist, the prDtec-ting polyethylene film with the thickness of 40 ~ is strip-ped-off, the drg film phDtoresist is applied onto the surface of the copper substrate bg means of a press-laminator at the temperature of 80C in the vacuum of 5 mm ~g. Then the pol~meric film based on cellulose triacetate is stripped off from the resulting sample and exposed as described in the foregoing Example 1.
~ he exposur~ time i6 54 sec. The development of the light sensitive layer is effected by means of a 1% agueous solu-, j~C)7 :: ' tion of sodium carbonats . The lager of polyvin~l alcobDl positio~ed on the surface of the li~ht-sensitive layer is diss~lved during tbs development.
The minimal reproducible line is 20~ . The base warping dDes not exceed 1 mm. ~he prior art drg film photoresist in-corpDrating a single-layer of cellulose triacetate of the same tbickness (103 ~ ) has a lower resolving power and re-produces lines witb the minimal thickness of 250r under similar testing co~ditions.
The msnufacture of the prior art photoresist with a sin-gle-layer base of pol~vinyl alcohol witb the thickness of 3J~
: i9 impossiblo due to a considerablo warping of the baso and a 1DW strangth thereof hindering tbe casting of the light-sensitive layer.
Example 3 A dry film photoresist incDrporates a film base co~sist-ing of a polg~thylenet6rephthalate substrate with the thick-ness of 25 J~ and an intermediate polymeric layer based oa a copolym~r of vinylidens fluoride with hexafluoropropylene with the thickness of 7 J~ . A light-ssnsitive layer with ths thickness of 7J~ having the same composition as in tho fDregoing Example 2 is deposited onto the surface of the in-termediats layer of the base. The photDresist is applied onto a copper 9ubstrata at the temperatur~ of 100C following the prooedure doscribed In EXamplo 2. The poI~eth~Ieneterephtba-`', ;. . -. ~ , .

-- \
1143~ 7 late substrate is stripped-off prior to the exposure. The ex-posure time is 45 sec. After the exposure tbe intermediate polymeric layer positioned ovor the surface Df the ligbt-sen-sitive layer is removed by mechanical way (stripped-Dff) as well. ~he development is conducted as described in Example 2.
The prior art dr~ film photDresist inc~rp~rati~g a single-layer pDl~etbyleneterephtbalate base with the thickaess of 32 ~ is capable of reproducing lines with the minimal tbick-. ~ .
ness of 120 ~
The prior art photoresist with a single-layer base of a copolymer of vinylidene fluDride witb h~xafluoroprop~len~
with the thickness of 7r has warpin of up to 10 mm due tD
stretcbing of tbe basc UpDn its displacement, thus hindering the use ~f the photore 9 i st.
Example 4 ; A dry film pbotoresist incorpDrate~ a fil~ base consist-ing of a solid polymeric substrate based on cellulose triac~-tate with the thickness of 70J~ and an intermediate pol~-mQriC lagsr of photographic gelatine of the tbickness of 10~
Onto the surface of the i~termediate polymeric layer a light-- sensitive layer with the thicknsss of 20~ and having tho 9ame compo~ition 88 in Example 2 is applied. The photoresist is deposited as de~cribed in EXample 2 ~ereinbefore. The layer of gelatin~ placed upon tha surface of the light-sensitive la-~er is diasolYing d~ring the devslopment. The developm~nt is ....

' j . " .

-1~3~:V7 effected as in Example 2. The minimal reproducibla llne i930r . The base warping doe~ not exceod 1.5 mm. Tbe prior art dr~ film photoresist incorporating a single-la~er baso Df cellU109e triacetate with th~ thickness of 80J~ reproduces linos ~ith the minimal thickness of 200J~ . The prior art dry film p~ot~resist witb a singlc-layer base of gelatinè
with the t~ick~ess of 10r hss but a low mechanical strengtb and warpi4g ~f up to 10 mm, thus hindsring its U90.
Bxample 5 A dry film phot~resi~t incorporates a film base CD~iSt-ing of a film of regenarated cellulose (c~llophane) witb tho thickness o~ 40 ~ and an intermediato polymeric layer Df a film based on polyvinyl alcohDl with the content of tho resi-.
dual ac~tate groups D~ ~ mol.% and the additive of 10% (bgweight of tho lay~r) of hgdrox~othylated dodecylphenol with the molecular weight of 500 units and bhs additive Df 0.75%
(b~ woigbt of tho layer) Df the d~estuff rhodamine GG (G) ~itb the thick~ess Df 15 ~ . OntD tbe surface of the dyed i~ter-mediate lagsr a light-sensitive laysr i9 deposited with the thickness of 15 ~ a~d having tho same compesition as in Example 2 ~ereinbefDre. Tbe u9e of tbe pbDtDresist is similar to that mentiDned in Example 2. Tbe layer vf pDlyvinyl alco-hDl is dissolved during the development. The development is effactod as in Example 2.-Tbe minimal reprDduciblo line i8 40 r . The base warping does not excesd 2 mm. The prior art -11~32V7 dry film ph~toresist incorporating a singlc-layer cellophane base with tbe thickness of 55r has 8 lower resDlving power and reprDduces li~es with the minimal width of 150~ . ~he prior art photoresist with a single layer base of polyvingl alcohol witb the thickness of 15~ and the same cDmpositiDn possesses an~nsatisfactory mecbanioal strength and has tbe base warping of up to 8 mm.
Example 6 A dry film photoresist contains a film base cDnsisting of poly-m-phen~leneisopbthalamide substrate with the thick-; ness of 30~ and an intermediate pDl~meric layer frDm a copol~mer of vinylidiene fluoride with tetrafluoroethylene with the thickne S9 of 5~ . Onto tbe surface of the inter-mediate layer a ligbt-sensitive layer with the thickness of 10r having the same composition as in Example 2 is deposit-ed. The intermsdiate layer positioned on tbe sur~ace of th~
light-sensitive layer is removed mechanically (stripped-off) prior tD the developmsnt. The development is effected as in Example 2. The minimal reproducible line is 20~ . The basa warping does nDt exceed 2 mm. The prior art dry film phDto-resist containing 8 single-layer base of pol~-m-pbenyleneiso-phthalamide witb the tbickness of 35J~ reproduces lines witb the minimal width of only 120~ . The prior art dr~
film photoresist with a single-layer base of a cDpolymer of vinylidene fluoride with tetrafluorDethylene with the thick-ness of 5r ha9 a 1DW mechanical strengtb and warping Df :.

up tD 1 mm hindering its U9e.
~xample 7 dry film phDt~resist cDntains the same lagers tbat the phDteresist described in Example 6, except that instead Df the c~polymer of vinylidene fluoride with tetrafluDroethyleno use is made of a copDlymer of vinylidene fluoride with tri-fluDrochlor~ethylene. The pbotoresi~t te9t9 are performed a9 described in Example 6. The pb~oresist characteristics ar~
not changed and correspDnd to the characteristics of the dry film photoresist Df Example 6.
Example 8 ; A dry film phDtDresist contains a film base co~sisti~g Df a pDlyethyleneterephthalate substrat~ with the thickness Df 15 ~ and an intermediate polymeric layer with the thickness of 12~ of polDhexamethyleneadipamide. OntD the surface of the intermediate layer there is depDsited a light-sensitive layer with the t~ickness ~f 10~ of the ~ame cop~sition as in Example 2. The intermediate pDlyhexamethyloneadipamide layer located on t~e surface of t~e light-sensitive layer is remDved (stripped-~ff) mecha~ically priDr tD the development.
The develDpment is effected as described in Example 2. The minimal reprDducible line is 30~ . ~be base wsrping i9 2.5 mm. The prior art pbotoresist containin~ a single-layer : base Df polyethyleneterephthalate with the tbick~ess Df 27 11~3207 reprDduces lines with the minimal widtb Df 75~ . The priDr art photoresist with a single-layer base of poly~exametbyle-neadipamide with th~ tbickness of 12J~ h~s the base war-ping Df up to 8 mm resulti~g in the fDrmatiDn of folds Dn the light-sen~itive layer.
Example 9 A dry film photoresist contains the same layers as the photoresist described in Example 8 , except tbat as the pDly-hexamethyle~eadipamide use is made of poly- ~ - caprD~mide.
The characteristics Df the dry ~ilm photoresist remain u~cha~g-ed and similar to those of the photoresist of Example 8.
Example 10 A dry film photDresist contains a film bsse cDnsisting of a polypyromellitimide substrate with the tbickness of 30 and an intermediate pDlymer layer Df pol~hexamethylene (adip/sebsc~amido (50 :50 mol.%) with the thickness Df 10~
Onto the surface Df the intermediate layer 8 light-sensitive layer with the thickness Df 15 ~ is deposited which has the same composition as in ~xample 2 hereinabove. The intermediato lager lDcated on the surface Df the light-sensitiYe layer is mechanically remDved (stripped-Df~)priDr tD tbe develop-m~nt. The davelopment is carried DU9 as described in ~xample 2. The minimal reproducible line is 40r . The base warping dDes nDt exceed 2 mm. The priDr art dry film photDresist ~ith a single-layer of pDlypyromellitimide film with tho thickne~s , --``` 1143207 of 40 ~ is capable o~ reproduci~g linea witb the mi~imal width of 150~ . ~be prlDr art pbotoresi~t uith a sin~le-la~er of poly~examethyle~e(adip/sebac)smide with tho thick-ness Df 10r has an uo9atisfsctory mechanlcal strongtb and the base warping Df up tD 8 mm which hi~ders its use.
EXampl~ 11 A drg film photoresist contains a film base c~nsistin~
o~ a pol~etbDle~eteropbthalato substrate with the thickness of 30 ~ and an intermediate polymeric layor of a copolymer of vinglidene fluDride witb tetrailuor~ethyleae witb the thickness ~ 4r . ontD the surface of the inter~diate layer thero is applied a light-~ensitivo la~or with the thick-nsss of 4~ havi~g the following cDmposition, g:
copolymer of styre~e with monoi~oamvl maleate . 100 pentaerytbritol tetraacr~lato 20 methacr~lated resin based on 2~2-bis-(4'-hydroxyphe~yl)propane (~w. 600 u~its, the co~tent of the rcsidual epoxy groups 0.28 wt.%, acid number 3,7 mg KOHfg) 20 acr~lamide 10 benzoin metbylate 5 dysstuff "basic blue E" 0.35-The dr~ film photoresist is subjected to the testi~ a~
described i~ Exampl~ 2 ~er~i~before.

~..

11~3Z07 ~ e intermodiate la~er lDcated on the surrace o~ tb light-sensitive la~er is m~chanlcally removod (stripped-ff) priDr to the de~elopme~t. Tbe developing ag~nt 19 a 1% aque-DU9 ~DlUtlotl D~ sDdium carbonat~.
Tbe minimal reproducible line ia 5J~ he base wsrplng does not excood 2 mm.
Tbe prior art dr~ film pbotora~ist containing a single-lager basa of polyethyloneter3phtbalat~ with tbo thickness of 34 r reproduces lines with t~e minimal width ef 90J~ .
~h~ prior art dr~ film photeresist with a single-layer of a copol~mer of vinylideno fluoride with tetrafluDroethy~flend wit~ tb~ tbickness of 4~ pDssesses a lo~ mecbanical strongth and tho base warping of up to 8~ binderi~g its us~.
Example 12 A dr~ iilm photoresist hs9 the 9ame cDmpDsition as in th~ foregoing Example 11, the pol~ethyle~etersphtbalste sub~trabe ha~ the thickness o~ 100 ~ , the intermediate polymer layer - tbe tbickn~ss of 8J~ , and t~e light--sensitive layer contains the followi~g e~mponents, gs product of interaction of epoxy resin based on 2,2-bi~(4'-h~drox~phenyl)-propa~e with acrylic anhydride (N.w. 1,500 units, the content of rcs~dual epox~ groups of 0, acid , numb~r o~ 2.1 mg K0~/g, bydroxyl number of 3.2% bg weight) triethyleneglgcol diacetato 10 Michler ketone 3 fluDrenone 3 dyestuff basic bluo '~" 0.25.
Tbe tbick~ss ~f tb6 light-sensitivo lager is 10~
Tbo dry film ph~toresist is sub~ected to tbe test3 .. . . .
doscrib~d in EXampl~ 2 hereicboforo. The intermediata lager i8 removsd m~chanicall~.
Th~ devoloping age~t is metbylchloroform.
Th~ minimal reprDducible lin~ is 25 ~ . Th~ base warping dPes nDt ~xceed 1 mm.
The prior arb film photDresist with a single-laysr base of pDlyethylenotsrephthalate with the thickness Df is capable ~f reproducing linos with tho minimal width oi 250J~ . Tb~ prior art photoresi~t with a single--la~er base o~ a copDlymer Df Yinglidene fluoride with tetrafluorDethglene with $be thickness of 8~ has th~
base warping of up to 6 m~, hinderi~g its uso.
~ Xampls 13 A dr~ film p~otoresi~t bas thc s~me compDsition and the layor thickness as i~ Example 12, thDugh tbo ligbt-se~-.

1~43207 æitive layer has tbo following cDmposition, gsa product Df interactiDD Df epoxy r~sin bas~d on 2,2-bis-(4'-bydroxyphe~gl)propane witb p-bo~zo~bonzDic acid and acr~lic anhydrido (M.w. 1,650 unit~, content of tbo residual epDxy groups i8 O, acid number 1.6 mg XOH~g, hydrDxyl ~umber 3% by weight, the co~tent of cDmbined p-benzDylbenzoio acid is 5.2% b ~eight) 100 triothyl~n3glycDl diacotat0 10 dyestu~f basic blue '~" 0.25.
Tbo tests Df tho ph~torcsist arc ~-Dnducted a~ doscribed in thc forogoing EXamplo 12. Tbe phDtDresist cbaracteristics are tbe sam3 as in Examplo 12.
E~ample 14 The dr~ film phDtDrosi9b is similar, as tD it~ composi-ti~n and tbick~oss, to that described in Example 12, but its ligbt-sensitivo la~r has the followi~g composition, g:
a prDduct of chemical additiDn of p-benzo~lbonzDic acid to a~ ep~x~ resin based on 2,2-bis-(4'-hydr~xypbeDyl)-propane (M.w. 1,200 units, the content ~i tbe residual OpD~y grDups is 2.8% b~ woight, tbo acia number i8 0.3 mg ~OH~g, tho hydroxyl number is 5.3% by weigbt, tho contont Df combined p-bonzDyl-be~zoic acid i9 20.1~) 100 pontaorythritol totraacr~late 200 The pbotorosist is subjected t~ testY a~ doscribod in -- 11432~7 : --25--, . . .
~xamplo 12. ~ho photorosist c~aracteristics remain unchanged.
~xample 15 . .
. A dry film photDrosist contains a ~ilm baso oonsisting ;. of a pol~eth~lc~eterephthalato substrato with tho thicknoss f 30 ~ and an intermedlate polym~r lay~r with tbe thicknoss of 9~ of pol~eric acr~lic acid nitrilecontaining 0.01% by woigbt cf tbe d~e~tuff ba~ic bluc "K".
Ont~ th~ sur~aco Df the interm~diato layer a light-~n-; j siti~e layer i~ deposited with the tbickn~ss Df 12 havi~g the composition de~cribed in hxampl~ 12.
Tho tests of tbe photorasists are carried out as d~sc-ribed in EXample 12.
. ~he minimal reprDducible lina is 30J~ . ~hg bago warping does not oxceed 2.5 mm.
; The dry film photoresist of tbe prior art witb a single-layer baRo of polyethyleneterephthalato with the thick~ess f 39 r i9 cspabl~ of reproducing lines with thc minimal thick~oss Df 70 ~ . T~a prior art pbotore~i~t ~ith a ~inglo-layer baso of polymeric nitril~ of acrylic acid with the tbic~ne~ o~ 9J~ has warping of up to 6 mm.
Examplo 16 A dr~ film pbotorosist ha8 tho 9ama compositi~n and thick~e3s a~ that dcscribod in tb~ foregoing Examplo 15, though its intermediatc layer is mado Df collulose diacetate.

: ~143Z~7 . , .

` .

Tho tosting precedure and prDperbios Df tbe phDtore~lst dc n~t differ from thoss oi Example 15.
; Egampl~ 17 . .
A dry fllm ph~tDresist contains a film bAse cDnsisti~g of polgp~romellitimide substrate with tha tbickness D~
30 ~ a~d an intermediatc pol~m~ric la~er with tho tbickn~ss of 8 mcm of pDlyethgls~eterepbthalats. Onto the surfacc vf t~e intermediate la~er a light-se~sitive lager with the th~ckness Df 10r a~d tho c~mpo9ition Df hxample ~2 i8 appliod. Tbo testing proceduro i8 similar t~ t~at ~f Bxample 12. Tha minimal reprDducibl~ line i8 25 ~ .
The baso warping dDes not o~caed 2.5 mm. Tbo priDr art film phDtDresist with a single-laDer base of polgpyrDmellit-imid- layer witb the thickness of 38~ is capable ~f repro-ducing lines witb the minimal width Df 7JU
Tbe priDr art phDtoresist with a single-lager of pol~-ethgleneterephthalate with the tbicko~ss ~f 8J~ has warpi~g of up to 6 mm.
Example 18 A dry film photDresist cDntains a base cDnsisti~g Df a p~lyethglensterephthalat~ substrate with tbe thickness D~
40 r and an intermediste polDmeric laDer deposited tbereon-:

: -27-, .

to and baving thickness Df 6~ ; it bas tbe followi~
cDmpooibion, g:
metbylcallulose witb ths substitution degreo Df 1.5 100 sodium salt of dibut~lnapbthalsne sulpbonic acid 0.5 dyestR~f rhodamine G&(G3 0.1.
Over tbe intermediate la~er a light-sonsitive layer i9 applied which has tbe 9am~ compo9ition as in Example 1 and the thickness o~ 15 ~ . -Tbe testing procedure i9 ~imilar to that dsscribad in~xample 1. ~hs minimal ~eproducible line is 30~ . ~bo base warping does not oxceed 1.5 mm.
T~e priDr art dr~ film pbotoresist with a single-layer ba~s of polyet~yleneterephthalats ~itb tbe thickness o* 46 i8 capable of reproducing linos witb tbe minimal thickn~s D:e 90 J~ .
~ be prior art pbotoresist witb a single-lager base Df metbglcellulose o~ tbe above-mentionsd composition a~d tho tbickness Df 6 r ba9 a low m~cbanical strengtb whicb hin~ers its uso.
Egample 19 A dry film photoresi8t ba9 the same composition and thickness as in ths foregoing Example 15, thougb its inter-. 11~3Z(17 mcdiato la,~er i8 mada D~ ce~llulo80 triacetat~.
Iho testi~g proceduro and tho ~hotoresist cbaracteristic~are slmilar to tbosc described in E~ample 15.

Claims (12)

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

1. A dry film photoresist comprising a flexible laminat-ed system incorporating:
a solid polymeric substrate with a thickness of from 15 to 100 µ ; an intermediate polymeric layer transparent to UV-radiation within the range of from 300 to 400 nm with a thickness of from 3 to 15µ consisting of a compound selected from the group covering a polymeric alcohol, a polymeric ester, a polyamide, a halogenated polymer, polyacrylonitrile and mixtures of these compounds; a light-sensitive layer with a thickness of from 4 to 20 µ
containing at least one light-sensitive compound capable of forming free radicals upon exposure to UV-radiation, at least one unsaturated compound containing in its molecule ethylene-like ?C=C? bonds and at least one polymer comprising the film-forming component of the light-sensitive layer;
a protective polymeric film with a thickness of from 5 to 50µ located above the light-sensitive layer;
all these four layer being bonded therebetween by adhesi-on forces so that the adhesion of said polymeric protective film to said light-sensitive lager is less than the cohesion strength of said light-sensitive layer, the adhesion of said solid polymeric substrate to said intermediate polymeric layer is less than the adhesion of said intermediate polymeric layer to the light-sensitive layer and the adhesion force of each of said three layers is less than the cohesion strength of each of said layers.

2. A dry film photoresist according to Claim 1, wherein as the polymeric alcohol its intermediate polymeric layer contains a compound selected from the group consisting of water-soluble methylcellulose and polyvinyl alcohol.

3. A dry film photoresist according to Claim 1, wherein as the polymeric ester its intermediate polymeric layer contains a compound selected from the group consisting of cellulose triacetate and polyethyleneterephthalate.

4. A dry film photoresist according to Claim 1, wherein as the polyamide its intermediate polymeric layer contains a compound selected from the group consisting of polyhexamethy-leneadipamide and gelatine.

5. A dry film photoresist according to Claim 1, wherein as the halogenated polymer is intermediate polymeric layer contains a compound selected from the group consisting of a copolymer of tetrafluoroethylene with vinylidene fluoride and a copolymer of trifluorochloroethylene with vinylidene fluoride.

6. A dry film photoresist according to Claim 1, wherein as the polyacrylonitrile its intermediate polymeric layer contains a polymeric nitrile of acrylic acid.

7. A dry film photoresist according to Claim 1, wherein the intermediate polymeric layer also incorporates dyestuff in an amount of from 0.01 to 1.0% by weight of the interme-diate layer.

8. A dry film photoresist according to Claim 7, wherein as the dyestuff its intermediate polymeric layer contains rhodamine GG (G).

9. A dry film photoresist according to Claim 1, wherein the intermediate polymeric layer contains also plastifying agents in an amount of from 5 to 15% by weight of the inter-mediate layer.

10. A dry film photoresist according to Claim 9, wherein as the plastifying agent the intermediate polymeric layer contains hydroxyethylated dodecylphenol.

11. A dry film photoresist according to Claim 1, wherein the intermediate polymeric layer also contains surfactants in an amount of from 0.1 to 0.5% by weight of the intermedi-ate layer.

12. A dry film photoresist according to claim 11, wherein as the surfactant it contains a sodium salt of di-butylnaphthalene sulphonic acid.