DE3741385C2 - Solder mask coating that can be imaged by exposure - Google Patents

Description

The invention relates to a photosensitive resin composition, especially one for Formation of a protective cover film with excellent Properties that are used only to train one photosensitive sticky coating or in Mix with a number of other types of Components like a crosslinker to increase the Crosslinking density, a resin to eliminate the Stickiness or even with another photosensitive Component to increase sensitivity to light can be used. The photosensitive coating according to the invention can thus be used for the production of photoresists such as Plating and etching resists, as well as solder masks used will.

Solder masks are used to manufacture printed Circuits used and primarily serve to prevent the formation of solder bridges, for Maintaining electrical insulation between the conductors to conduct a line this way between the soldering areas and the corrosion of a to prevent bare copper conductor. Besides, is it is desirable to have imaging over exposure To have solder masks that are capable of Keeping picture used as a break on which the solder is applied. There an increase in wiring density is desired it is also desirable to have a solder mask too use that high resolution as well  has extremely good insulation properties. These The photosensitive according to the invention has advantages Composition on.

Soldering masks are known from US Pat. No. 4,499,163, in described a photosensitive resin composition which is a urethane diacrylate or dimethacrylate, an unbranched polymer compound with a glass transition temperature in the range of approx. 40 to 150 ° C and contains a sensitizer which generates free radicals under the influence of UV light. The described unbranched polymer compound comprises unbranched vinyl polymers or copolymers, such as e.g. B. polymers of vinyl monomers, the methyl methacrylate, Butyl methacrylate, methyl styrene, vinyl toluene and the like. The sensitizer for Generation of free radicals includes e.g. B. substituted and unsubstituted polynuclear quinones.

Another light curable urethane acrylate resin composition, those for making permanent resists can be used is in US-PS 45 87 201 described. The urethane acrylate described there Composition is made of polybutadiene polymer composed and becomes the formation of the permanent Resists mixed with a photopolymerization initiator.

Most solder masks that can be imaged by exposure have the disadvantage, however, that they are in an aqueous Solution can not be developed. This makes the use of developer solutions on the An organic solvent base is required.  

However, the use of organic solvents due to environmental protection regulations solvent pollution undesirable.

Another disadvantage of solder masks, for their development Solutions based on an organic Solvent is required is the persistent Sensitivity of the end product to organic Solvents such as methylene chloride. With certain Product applications is also one of them Sensitivity undesirable.

It is therefore an object of the invention by exposure imageable coating compositions to develop for solder masks that are in aqueous Solutions can be developed and the opposite resistant to organic solvents such as methylene chloride are. This task becomes, as from the above claims evident, solved.

The object of the invention is to provide such a coating composition. Another The object of the invention is to provide a coating composition for solder masks, those with commercially available alkali thinners can be removed. The described photosensitive Resin compositions accordingly have excellent resolving power, their flexibility, their adherence on metals, their resistance to solvents and high temperatures as well as excellent electrical Insulation properties.

According to a special embodiment of the invention becomes a highly viscous photosensitive material  provided that as an additive for compositions is suitable, the addition of both a thickener, as well as a photosensitive Require coating material. The present photosensitive materials thus fulfill one double task, namely that of a thickener, as well as that of a light sensitive, light-curable additive. Such embodiments of the compositions according to the invention thus suitable light-sensitive, light-curable Thickeners for fabrics such as B. colors, inks etc.

A photo-curable coating composition comprises a UV sensitive compound selected from carboxylated urethane diacrylate, carboxylated Urethane triacrylate, carboxylated urethane dimethacrylate and carboxylated urethane trimethacrylate. The following is called carboxylated Urethane di (and / odedr) tri (meth) acrylate referred to this group. Below is (meth) acrylate to understand acrylate and / or methacrylate.

These carboxylated urethane di- and / or tri (meth) acrylates are made from acid fragments that Provide carboxyl groups. These compositions by condensation of a diisocyanate, a polyol carboxylic acid and a hydroxyalkyl (meth) acrylate receive.

The polyol carboxylic acid should contain an amount that is required to at least 0.3 milliequivalents of acid per gram (meq / g) Mix of the total amount of reagents - usually these are diisocyanate, polyol carboxylic acid and hydroxyalkyl (meth) acrylate - to ensure. Around  a suitable level of light sensitivity with this product to achieve the used Hydroxyalkyl (meth) acrylate in a minimum amount of approx. 0.5 meq / g of the total amount of diisocyanate, Diol or triol carboxylic acid and hydroxyalkyl (meth) acrylate are present.

The invention includes a number of embodiments that are realized by coating composition mentioned above with other specifically selected components. These components that are selected to be a ensure specific quality or property or improve, include a binder, a crosslinker, dyes, pigments, thermopolymerization inhibitors and additives that go with it are determined, the coating properties too improve.

The photocurable coating composition contains the carboxyl portion, which is the organophilic nature changed the urethane (meth) acrylate polymer. Thereby become the coating compositions of the invention more organophobic and therefore permanent against organic solvents such as methylene chloride. In addition, the carboxylated photosensitive Polymers in bulk with others hydrophilic binders and crosslinkers mixed will. In addition, through the introduction the carboxyl portion of the coating compositions of the invention in aqueous alkali solutions (pH above 7.5) soluble until exposure to UV light or swellable. Advantageously, at Use of the compositions according to the invention for the production of a light-curable coating or solder mask the development stage in aqueous alkaline  Solutions are carried out. It can thus, the sensitivity the connection to UV light despite the fact that the incorporation of the carboxyl portion too leads to a change in the urethane (meth) acrylate, whereby it becomes soluble in aqueous alkali remains. The carboxylation also improves adhesion to metals. Through the Mixture of a binder, a crosslinking agent and a carboxylated urethane and / or tri (meth) acrylate you get an improved solder mask. In a preferred blend is a copolymer of Styrene and maleic anhydride as a binder, the also provides carboxyl groups used. Preferred Crosslinkers are (meth) acrylate and polyfunctional (Meth) acrylate monomers.

Preferred carboxylated urethane di- (and / or) tri (meth) acrylates can be represented are represented by the formula I

where n is an integer from 1 to 4 and k can mean both 0 and 1 and wherein R₁ of the acrylate reaction component c) is derived and Is hydrogen or methyl, R₂ of the hydroxyalkyl (meth) acrylate reaction component c) is derived and an unbranched or branched hydrocarbon fragment with 2 to 28 Is C atoms and R₃ is derived from the Diisocyanate component of the reaction mixture. R₃ can a branched, unbranched or cyclic saturated, unsaturated or aromatic hydrocarbon fragment represent R₃ has 4 to 20,  preferably 6 to 18 carbon atoms. With others preferred Embodiments is derived from R₃ a diisocyanate reagent selected from the group consisting of trimethylhexamethylene, hexamethylene, Isophorone, tolylene, 4,4'-methylbis (cyclohexyl), methylene diphenyl and tetramethylxylene diisocyanate. R₄ is a straight, cyclic or branched, aromatic, saturated or unsaturated hydrocarbon with 2 to 28 carbon atoms R₄ can optionally also a hydroxyl (of which in the Preparation of the composition used polyols) contain. R₅ is derived from a reaction mixture, containing a) those in formula II polyol carboxylic acid shown and described or b) the polyol carboxylic acid of formula II and in Formula III shown and described hydroxyldicarboxylic acid. R₅ thus always contains at least a COOH group and at least 3 carbon atoms. Is R₅ of a) (i.e. only from the compounds of formula II) derived, it contains only one COOH group a branched or unbranched, saturated, unsaturated or aromatic hydrocarbon residue with a total of 3 to 30 carbon atoms inclusive of the C atoms of the carboxyl. If R₅ and b) are derived, so in the overall composition are R₅ groups that derived from the polyol carboxylic acid of formula II are, and also R₅ groups by the hydroxyl dicarboxylic acids of the formula III are derived available. That of the hydroxyl dicarboxylic acid compounds of the formula III derived R₅ groups thus clearly have two COOH groups and can also contain 3 to 30 carbon atoms including the Have 2 carbon atoms of the carboxyl. The description contains the compounds of formula II and III more information regarding concentration and the preferred structures of these R₅ groups.  

It is understood that the exact location of each R₅ grouping within the polymer molecule by the number the reactive hydroxyl groups of the compound in formula II or III as well as from the somewhat random condensing reaction depends. Is z. B. R₅ derived from b) and means y in formula III 1, R₅ is a terminal group with two COOH groups. At the same time, other R₅ groups are out the same reaction mixture (derived from the Polyol carboxylic acid according to formula II), as in formula I. indicated, arbitrarily in the skeleton of the polymer molecular structure arranged.

In formula I the group R₂ preferably has 2 to 16 C atoms or is in particular a grouping selected from the group of ethyl, propyl, butyl and

where m is 1 or 2.

R₄ is derived from the polyol, which is optionally is added to the reaction mixture. R₄ therefore has 2 up to 28 C atoms and 2 to 5 O atoms. The O atoms can optionally in an unreacted OH group be included. If R₄ is present, it has 2 up to 28 carbon atoms on or preferably 2-18 carbon atoms, where appropriate, there is also an OH group having. In other preferred embodiments R₄ is a saturated or unsaturated hydrocarbon group with 2 to 10 C atoms and 2 to 5 O atoms, possibly in the form of an unreacted OH group. In the specific examples  for such preferred embodiments, R₄ a group selected from ethyl, propyl, butyl, Pentyl, hexyl, heptyl and octyl and has 2 to 5 O atoms that come from the above OH groups. R₄ can also from glyceryl or 2-ethyl-2- (hydroxymethyl) -1,3-propylene be derived.

The carboxylated urethane-di- (and / or) tri (meth) acrylates can by condensation a diisocyanate with a polyol carboxylic acid (see formula II) and a hydroxyalkyl (meth) acrylate can be obtained in a one-step reaction. The Polyol containing carboxyl groups can be any Carboxylic acid with 2 or more, optionally with 2 to 5 OH groups, but preferably one Diol or triol carboxylic acid.

The polyol carboxylic acid therefore suitably corresponds Formula II below

[HO] _x -R₆-COOH

where x is an integer from 2 to 5 and R₆ is one branched, cyclic or unbranched, saturated, unsaturated or aromatic hydrocarbon group with 2 to 29 carbon atoms. Preferably R₆ has 2 to 24 carbon atoms and x is preferably 2 or 3 (such as a diol or triol). X 2 and R₆ are particularly preferably branched or unbranched, saturated, unsaturated or aromatic hydrocarbon structure with 2 to 20 C atoms. A preferred embodiment is used an α-α-dimethylolalkanoic acid as carboxylated Diol, which is particularly preferably an alkyl having 1 to 8 Contains carbon atoms. Other preferred diol carboxylic acids  are selected from the group consisting of α-α-dimethylol acetic acid, α-α-dimethylol propionic acid, α-α-dimethylol butyric acid, α-α-diethylolacetic acid, α-α-diethylolpropanoic acid, α-α-dipropylolpro pionic acid, α-α-dipropylol butyric acid and 2,3-di hydroxylpropanoic acid.

If necessary, a polyol can be added to the reac tion mixture are added. This will make the Molecular mass of the product according to the invention elevated. The presence of a polyol leads to substances as shown in formula I, wherein k is 1 are.

One embodiment of the present invention is particularly preferred at a higher concentration is provided on hydroxyl groups (such as e.g. B. by adding a polyol or by use a carboxylic acid according to formula II, wherein x 3, 4 or 5 means). In this embodiment a hydroxyl dicarboxylic acid to the reaction mixture given. Suitable hydroxyl carboxylic acids are by Formula III shown

[HO] _y -R₇- (COOH) ₂ (III)

wherein y is 1 to 5 (preferably 1 to 3) and R₇ an unbranched, cyclic or branched, ge saturated, unsaturated or aromatic hydrocarbons group means 1 to 28, preferably 1 to 18 and particularly preferably 1 to 12 carbon atoms contains. If y is 2 to 5, R₇ preferably has 2 to 18 carbon atoms. These diacids should then preferably used when the concentration of hydro xyl groups in the entire reaction mixture at least  approx. 0.3 meq OH groups per gram total amount Reagents (diisocyanate, polyol carboxylic acid, hydro xylalkyl (meth) acrylate, hydroxydicarboxylic acid and, ge if necessary, polyol). These diacids can suitably in an amount of about 0.3 to about 0.7 meq of acid per gram of total amount Reagents are used. Suitable hydroxy dicarboxylic acids can be selected from the Group consisting of apple, wine, dihydroxy wine, Hydroxyadipine, Dihydroxyadipine and Trihydroxadi pinic acid.

This dicarboxylic acid can be used to provide thermosetting free terminal groups used will. These end groups can advantageously also reactive positions for the future order surrender with other substances. So z. B. Melamine and epoxy two compounds or groups, implemented with the terminal carboxyl groups will. Such implementations can Properties of the substance further modified or be improved. The specific ones you want Properties or qualities depend on the dist intended use of the substance.

To produce the coating according to the invention composition based on carboxylated Urethane di (and / or) tri (meth) acrylate is the Implementation in a dry solvent solution performed that not even with the isocyanate responds. Corresponding examples of such Lö solvents are esters such as ethyl acetate and propy lenglycolmonomethyletheracetate, ketones such as methyl ethyl ketone, methyl isobutyl ketone and N-methyl pyrro lidon, aromatic hydrocarbons such as toluene and  Xylene and mixtures of these compounds.

The implementation for the preparation of the invention Coating composition is at a Solids content of the solution in a range of approx. 20 to about 100 wt .-%, preferably in a range from approx. 35 to approx. 95% by weight and in particular from approx. 65 to about 85 wt .-% performed. The reaction temperature is generally within one Range of about 50 to about 95 ° C, preferably between approx. 65 to 85 ° C. Preferably the homo polymerization by adding a radical poly merization inhibitors such as hydroquinone, m-dinitro inhibited benzene, phenothiazine, etc. Especially these inhibitors are used in an amount of approx. 0.005 to about 1 wt .-%, based on the solid matter important, used.

Condensation catalysts are also preferred such as tin or amine catalysts used. These can be selected from the group dibutyl Tin dilaurate, dimethyl tin diene decanoate, dibutyl Tin bisoctylthioglycolate, triethylamine and triethy lendiamine. For optimal results the reaction becomes drier with overlaying Air performed.

The diisocyanate can be a branched, unbranched or cyclic, saturated, unsaturated or aromatic hydrocarbon. Usually it contains 4 to 20, preferably 6 to 18 carbon atoms. Diisoxyanates can be selected from the group consisting of xylylene diisocyanate, 1-isocyanate 3-isocyanat-methyl-3,5,5-trimethylcyclohexane, 3,3′- Dimethyldiphenylmethane-4,4'-diisocyanate, 2,4-toly  lene diisocyanate, 2,6-tolylene diisocyanate, 2,2,4-tri methylhexamethylene diisocyanate, 2,4,4-trimethylhexa methylene diisocyanate, methylene bis (4-cyclohexyliso cyanate), hexamethylene diisocyanate, m-tetramethylxy lol diisocyanate, p-tetramethylxylene diisocyanate, Methylene-bis-phenyl-diisocyanate, 1,5-naphthylene-di isocyanate, m-phenylene diisocyanate and mixtures thereof. Most preferred are 2,6-tolylene-di isocyanate, 2,4-tolylene diisocyanate, 1-isocyanate-3- isocyanatmethyl-3,5,5-trimethylcyclohexane, 2,2,4- Trimethylhexamethylene diisocyanate and 2,4,4-tri methylhexamethylene diisocyanate.

When using a polyol, the molecular mass, the curing speed and the ver increased wetting density. The polyol can be 2 to 28 Contain carbon atoms. The hydrocarbon is common Part of fabric branched or unbranched, saturated, un saturated or aromatic and contains 2 to 5 Hydroxyl groups. The polyol is preferably a Diol or triol with 2 to 16 carbon atoms. Preferred Diols can be selected from ethylene glycol, Propylene glycol, butanediol, pentanediol, hexanediol, Octanediol, neopentyl glycol, 2-methylpropane-1,3-diol, Cyclohexane dimethanol and diethylene glycol. Further preferred polyols are glycerol, trimethylolpropane or hexanetriol, which are also used can.

The hydroxyalkyl acrylate (Component c) contains an alkyl with approx. 2 to 28 C atoms. This alkyl can also be branches, cyclic or branched and saturated or be unsaturated. Preferably the alkyl has Hydroxyalkyl (meth) acrylate 2 to 12 carbon atoms. Before  Preferred hydroxyalkyl (meth) acrylates can be made from Hydroxyethyl, hydroxypropyl and hydroxybutyl (meth) acrylate and from compounds of the formula

where m is 1 or 2.

In the production of the coating according to the invention composition should be the concentrations of Reagents should be chosen so that the total concentration tion on OH groups at least approximately the Diiso amount of cyanate. This means on the whole and whole that the concentration of polyols plus Diols of dialkylol carboxylic acid plus hydroxyl (meth) - acrylate is sufficient to the ratio of hydroxyl to Diisocyanate to at least about 0.95: 1 and preferred set to at least 1: 1. Especially the OH portion should be present in the equivalent excess. Preferably, the hydroxyl portion should be in one Equivalent excess, based on the diisocyanate, in Range from about 1.05: 1 to about 0.95: 1, especially from 1.02: 1 to approx. 1: 1.

The polyol carboxylic acid is an important component the coating composition of the invention and is preferably present in an amount consisting of enough to contain the uncured copolymer in aqueous To make alkali solutions soluble or swellable. The polyol carboxylic acid may be in one Minimum amount of approximately 0.3 meq of acid per gram of Ge total amount of reagents, preferably in one amount of 0.5 meq acid per gram total amount of reagents or above.  

The polar solubility is further improved, when the polyol carboxylic acid in the reaction mixture in an amount of more than 0.8 meq of acid per gram of Ge total amount of reagents is used.

The preferred range of milliequivalents of acid per The total amount of reagents is between approx. 0.8 and 1.6. Becomes a highly viscous product that is particularly suitable for mixing with others The reaction mixture should contain substances in particular a minimum amount of about 1, be completely particularly preferably from about 1 to about 1.6 meq acid per Contains grams of total amount of reagents. The Diacid according to formula III can also add to the amount Milliequivalents of acid are added.

Another advantage of carboxylation Urethane and tri (meth) acrylates is that the UV-sensitive compound with hydrophilic resins can be mixed. Furthermore, the hydrophilic Character of this UV sensitive compound up to to some extent by changing the Concentration of carboxylation in the urethane and tri (meth) acrylates can be controlled. This he allows the hydrophilic character for a be the right resin. If e.g. B. the use a more hydrophobic or less hydrophilic Resin is desired, a low concentration of carboxylation in urethane and tri (meth) arylate used to improve tolerance to improve with the chosen resin. Conversely, one would, if using a hydrophilic resin is desired, the carboxylcon Raise the concentration so much that the resin and the Urethane and tri (meth) acrylate in larger cones  concentrations can be mixed together. The polyol carboxylic acid can in the reaction mixture Concentrations at an amount of carboxylated Polyol from approx. 5 to approx. 45% by weight, preferably approx. 5 to about 25% by weight and in particular from about 12 to approx. 25% by weight, based on the total amount reagents are used.

If a specific polyol is also used, so it can be in the reaction mixture in an amount of about 2 to about 18% by weight, preferably from about 2 to approx. 15% by weight, based on the total amount of rea gentia.

In the case of the diisocyanate, the concentration is usually about 30 to about 80% by weight, preferably about 50 to about 75 wt .-%, based on the total amount of reagents.

The hydroxyalkyl (meth) acrylate must be in the reaction mixture in a minimum amount of approx.0.50 mEqu acrylate per gram Total amount of reagents available to meet the required To ensure UV sensitivity. Ge a quantity in the range of approx. 0.5 to is suitable approx. 1.6 meq of acrylate per gram of total amount of reagents. The amount in% by weight is usually in the range range from about 5 to about 50 and preferably in Range from about 10 to about 30 wt .-%, based on the Total amount of reagents.

The coating composition according to the invention based on the carboxylated urethane di (and / or) tri (meth) acrylate copolymer usually has a molecular weight weight from about 500 to about 6500, preferably from about 800 to about 3000 and particularly preferably from  approx. 1000 to approx. 2500 (determined by Gelper meation chromatography and based on a standard calibration curve for polystyrene).

In a preferred embodiment, he coating composition according to the invention mixed with a binder. The used here Resin should preferably be a glass transition temp temperature of approx. 155 ° C or higher particularly preferably hydrophilic. The high glass over transition temperature improves the temperature resistance product. There can be various in the trade available resins can be used. Suitable Mixtures of the carboxylated according to the invention Urethane di (and / or) tri (meth) acrylates can advantageously by varying the carboxyl concentration can be achieved. For this purpose ge suitable resins are copolymers of styrene and malein acid anhydride, especially those containing alcohols with low molecular weight partially ver are esters. Copolymers are commercially available of styrene and maleic anhydride with alcohol mixtures (from methyl to butyl alcohol) esterified are. The molecular weight of such commercially available Copolymers vary widely. The molecular weight for this resin binder should usually be in the range of approximately 25,000 to approximately 300,000 and particularly preferably in the range of approximately 60,000 to approximately 250,000. Preferably points the copolymer has a styrene to maleic ratio acid anhydride from about 1: 1 to about 2: 1. The be preferred glass transition temperature of the binder lies in the range of approx. 155 to approx. 200 ° C.  

The binder can be used in an amount of approximately 85 to approx. 25% by weight, but preferably from approx. 17 to approx. 60% by weight, based on the total settlement, be used. Preferably the Coating composition based on carboxylated urethane di (and / or) tri (meth) acrylate mixed with the binder so that the Glass transition temperature of the end product approx. 70 up to approx. 190 ° C. The acid number of the binder is between approx. 120 and approx. 280 mg KOH per Grams of binder. As a binder together with the coating composition according to the invention on the Base of carboxylated urethane di (and / or) tri (meth) acrylate can use other polymers with the above described molecular weight and the above given glass transition temperature and acid number be used. Suitable polymers for ver Use as binders are u. a. Methyl methacrylate comethacrylic acid and methyl methacrylate-methyl acrylate methacrylic acid.

Is the carboxylated invention Urethane di (and / or) tri (meth) acrylate along with others Substances, such as the binders described above, or other additives that may be added such as B. crosslinking agents, dyes, solutions agents, pigments, photoinitiators or thermal Inhibitors used, so should the conc tration of UV-sensitive carboxylated Be layering component in the range from approx. 10 to approx. 85 wt .-%, based on the total amount of the total settlement, amount. It is preferably in the range from about 15 to about 75 and particularly preferably in Range from about 17 to about 60 wt .-%, based on the Total amount of the composition.  

Preferred crosslinking agents are (meth) acrylate mo nomers, crosslinking agents are then used if a higher crosslink density is desired. This in turn improves product stability speed towards solvents, such as. B. methylene chloride. Polyfunctional ones are particularly preferred (Meth) acrylate monomers. Such can be selected are made of trimethylolpropane tri (meth) acrylate, tri methyl propane ethoxylated tri (meth) acrylate, dipene taerythrithydroxypentaacrylate and Ditrimethylolpro pantetraacrylate.

Other crosslinkers that can be used can be selected from the group consisting of divinyl ether, acrylated epoxy compounds, epoxy resins and amino plastic resins can be selected. Those are preferred Acrylated epoxy compounds as they are the most resistant product against heat and Improve solvents and its adhesiveness.

When using the carboxy according to the invention gated coating composition as a solder mask the composition will be appropriate Apply substrate and then until non-sticky dried. Then the exposure of the be layered substrate by UV rays with approx. 75 to 105 mJ / cm², after which it is in an aqueous Alkali solution can be developed. Preferably the aqueous alkali solution is one of Potassium or sodium carbonate. As a rule, the by exposure of the coated substrate holding image of the solder mask now a visual Subjected to testing.

When using the combination according to the invention  it is advantageous that the coating optionally slightly with the help of an aqueous Alkali solution can be removed and then renewed. The amount of alkali required for the solution Develop or remove the coating is very low. Can be used a solution containing 1 wt .-% base. If the Image has achieved the desired quality the coating according to the invention additionally can be cured by UV light of 3 to 5 J / cm². Thermal curing is then preferably carried out at 150 ° C for a period of time for curing sufficient. The combination according to the invention Settlements have an excellent resolution ability, excellent flexibility and a excellent adhesion to metals.

The essence of the present invention is also light can be seen from the examples below. It it goes without saying that these examples are the only illustrate the present invention and it therefore do not limit. Nothing else is said all parts and percent are understood stated as parts and percentages by weight.

example 1

The following example illustrates the production a coating that can be imaged by exposure composition.

In a 5-liter round-bottom flask equipped with a mechanical Agitator, a thermometer, a con condenser, a gas inlet pipe and a heating jacket 236.0 g (approx. 4 equivalents)  1,6-hexanediol, 268.0 g (about 4 equivalents) dimethyl olpropionic acid, 951.2 g (approx.8.2 equivalents) 2- Hydroxyethyl acrylate, 0.23514 g phenothiazine as Radical polymerization inhibitor, 783.8 g N-methyl 2-pyrrolidone as solvent and 31, 35 g of dibutyl Tin dilaurate (T-12) presented as a catalyst. Be under a layer of dry air Stir 1,680.0 g (about 16 equivalents) trimethyl hexamethylene diisocyanate in two equal aliquots added to the mixture at an interval of 30 minutes ben. An exothermic reak occurs with each addition tion. The reaction temperature is controlled by cooling in kept in an ice water bath below 85 ° C. After Add the second portion of trimethylhexa methylene diisocyanate becomes the reaction temperature 10 kept constant at 85 ° C for up to 12 hours until the IR absorption maximum of the isocyanate disappeared is what indicates the completion of the reaction.

Example 2

The photosensitive coating composition according to Example 1 is used to produce a Exposure imageable solder mask used. The solder mask is made by using a 500th ml round-bottom flask, which with an agitator, a gas let tube, a thermometer and a condenser is equipped, 6.5 g of a low molecular weight copolymeric antifoam, 91.25 g of N-methyl 2-pyrrolidone as a solvent, and 82.0 g of one esterified copolymer of styrene and maleic acid anhydride as a binder. (Use this dete Harz is Scripset 550 from Monsanto). The Mixture is stirred for 30 minutes and at 95 ° C heats, after which a cloudy solution is obtained. After that  the temperature is reduced to 70 ° C and the following Components added to the mixture: 0.004 g Phenothiazine as radical polymerization inhibitor, 77.5 g of the UV sensitive coating together setting according to Example 1 and 9.0 g of a green Dye. While the mixture is under a stream dry air is kept, a preliminary prepared solution, the 47.8 g trimethylolpropane tri acrylate (SR351) as crosslinking agent, 6.5 g Iso propylthioxanthone (abbreviated ITX) as a photoinitiator and 8.4 g of ethyl p-dimethylaminobenzoate (abbreviated) EPD) is added as a sensitizer.

The above components are in dry air Mixed for 30 minutes at 70 ° C and then in a bern stone-colored vessel carried. The so obtained Solder mask was used as described in Example 3 turns.

Example 3

The composition prepared in Example 2 is as a coating on two 15.24 cm × 20.32 cm (6 ′ ′ × 8 ′ ′) large epoxy plates plated with bare copper in a thickness of approximately 0.0508 mm (2 mils) below Use a mesh with a mesh size of approx. 0.193 mm (75 mesh) made of monofilament polyester and a rubber roller with a durometer hardness of 70 applied. The wet coating will last 12 minutes dried in a circulating air oven at 100 ° C, where a 0.03556 mm (1.4 mil) thick non-stick film arises.

The dried films are then room temperature temperature cooled and at 75 mJ / cm² using a  400 W mercury vapor lamp through a negative Print template IPC (Institute for Interconnecting Packaging electronic circuits) No. B-25 exposed. The exposed films are then hand-made in one Developed 1% K₂CO₃ solution for 45 seconds and then rinsed with fresh water.

It will be an excellent resolution of the IPC B-25 achieved.

After developing, the plates are at 3 J / cm² hardened and then for one hour at 150 ° C for night curing hot dried.

One of the two plates is then left in for 15 minutes Methylene chloride (MeCl₂) immersed, being on the mask no decomposition is observed (test for Resistance to solvents).

The other plate is subjected to an adhesion test Cross-cut according to ASTM D3359-78 Method B below pulled, with no loss of liability is found. The plate is then loaded with a resin thinner paint and with the solder mask down in one Crucible on molten solder, 10 seconds at 260 floated up to 275 ° C. After this solder pot test the plate while it is still warm, so continued rinsed with 1,1,1-trichloroethane. One hour then the plate is again cross-cut test to check the coating adhesion unterzo gene, whereby no loss of liability is found can.  

Example 4

Using the equipment and process, described in Example 1 become urethane diacrylate oligomers with various carboxylation manufactured. Sample 4 contains no carb oxylation, whereas sample 9 has the highest carboxy has. All samples have a festival content of 80%. The composition of everyone individual sample is listed in Table 1.

Table 1

The abbreviations used have the following meaning tung:

DMPS = dimethylol propionic acid
2HEA = 2-hydroxyethyl acrylate
TMDI = trimethylhexamethylene diisocyanate
DZnN = dimethyl tin diene decanoate
M-pyrol = N-methylpyrrolidone
Equ = equivalent

The viscosity of samples 4 to 9 in Pa / s (cps) was at 24 ° C (75 ° F) using a Brook field RVT viscometer # 6 at one turn speed of the spindle measured from 10 rpm.

Example 5

Samples 5 through 9 of the carboxylated urethane acrylates are used to manufacture solder masks. These are then used to compare the properties tested. Example 5 is used together with the Examples 6 and 7 below to compare the Properties of the carboxylated urethane acrylates with Masks containing non-carboxylated urethanes.

The soldering masks referred to here as samples D to H are described with that in Example 2 Apparatus and according to the general described there Process manufactured.

The amount for each component is in the after following table:  

Table 2

Common formulation for the solder mask samples D to H

Bare copper-plated epoxy plates are coated with solder masks of samples D to H according to the general procedure described in Example 3. The plates are then tested and the test results evaluated.
Exposure speed: excellent for samples D to H at 75 mJ / cm².
Development: excellent for samples D to H in 1% aqueous K₂CO₃ solution. Weak when developing samples D to H in 1,1,1-trichloroethane.

Adhesion test: according to ASTM D3359-78 method B
(Grade 5 means no liability loss)
(Note 0 means total loss of liability)

Example 6

Samples of a solder mask composition are shown below Use of sample 4, a non-carboxylated Fabric as described in Example 2, prepared.

The components and the amounts used are in given in the table below:

Table 3

For the purpose of comparison, both wording (A and B) according to those described in Example 3 Process tested and for coating a bare, copper-clad epoxy plate used, which was also evaluated. The results nisse are listed below:

Example 7

A sample 4 is also used for comparison purposes used to make a photosensitive Elements, which is then based on its development in ver different types of solvents becomes. The photosensitive element (sample C) is prepared by mixing the components from Table 4 up to 50 ° C in a 500 ml round bottom flask, which is equipped with an agitator, a gas inlet pipe, a thermometer and a condenser sator.

In the table below is the quantity for each Component specified.

Table 4

Solder mask composition (sample C) containing a non-carboxylated urethane diacrylate (sample 4)

The non-carboxylated urethane diacrylate (sample 4) shows only a very limited compatibility with the styrene / maleic anhydride resin (Scripset 550). Homogeneous mixtures of the non-carboxylated Urethane diacrylate and styrene / maleic acid dridharzes could only be proportionate short time (less than a month) and only then be made when the ratio of the Urethane diacrylate to resin was less than 1. If If this ratio is increased, phases occur separation (sample B).

The carboxylated urethane or tri (meth) acrylate however, different carboxyl concentrations can have and is in every relationship with the Styrene / maleic anhydride resin and others than Bin Resins used are miscible and compatible. The result is excellent storability consistency, uniformity and very easy to process products.

Example 8

Carboxylated urethane triacrylate samples are used using those described in Example 1 Apparatus and according to the general given there Process manufactured. The specific, for each Components used in the triacrylate sample are in the following table.  

Table 5

The product of samples 10 and 11 then becomes Her position of the solder mask I or J used.

The solder masks are made using the in Example 2 used equipment and be there general procedure described.  

Table 6

Solder mask compositions based on carboxylated urethane, triacrylates

The plates used in the above tests were using samples I and J according to the method described in Process described in Example 3.

Claims (9)

1. Exposing coating composition, full a UV sensitive polymer selected from the group consisting of a carboxylated Urethane dimethacrylate, a carboxylated Urethane diacrylate, a carboxylated urethane triacrylate and a carboxylated urethane trimethacrylate, the polymer being made by condensation of a reaction mixture a) a diisocyanate with 6 to 18 carbon atoms, b) one Polyolcarboxylic acid of the formula [OH] x = R₆-COOH, where x is an integer from 2 to 5 and R₆ an unbranched or branched, saturated or unsaturated or aromatic hydrocarbon group with 2 to 29 carbon atoms, and c) a hydroxyalkyl (meth) acrylate, wherein each alkyl Has 2 to 28 carbon atoms, with the proviso that the Component a) in an amount of about 30 to about 80% by weight,  based on the total amount of the reaction mixture, component b) in an amount of approx. 5 up to approx. 45% by weight, based on the total amount of Reaction mixture, with a minimum amount of approx. 0.3 milliequivalents of acid per gram of total amount of Reaction mixture and component c) in one Amount of about 5 to 50 wt .-%, based on the Total amount of the reaction mixture, with a minimum amount of 0.5 milliequivalents of acrylate per gram The total amount of the reaction mixture is present. 2. Composition according to claim 1, characterized in that they additionally one Contains binders. 3. Composition according to claim 1, characterized in that that the reaction mixture additionally a polyol with 2 to 28 carbon atoms and 2 contains up to 5 hydroxyl groups. 4. Composition according to one of claims 1-3, characterized in that the reaction mixture additionally a dicarboxylic acid of the formula [OH] _y -R₇ (COOH) ₂worin y is an integer from 1 to 5 and R₇ is a hydrocarbon fragment with 1 to 28 C- Represents atoms contains. 5. Composition according to one of claims 1-4, characterized in that the component b) is additionally selected from the group, consisting of α-α-dimethylol acetic acid, α-α-dimethylol propionic acid, α-α-dimethylol butyric acid, α-α-diethylolacetic acid, α-α-diethylolpropionic acid and α-α-diethylbutyric acid.   6. Composition according to one of claims 3-5, characterized in that it is a Has binder which is a styrene / maleic anhydride copolymer with a glass transition temperature 155 ° C or higher. 7. Composition according to one of claims 1-6, characterized in that the reaction mixture about 0.8 to 1.6 milliequivalents of acid contains per gram total amount of the reaction mixture. 8. Composition according to one of claims 1-7, characterized in that the Diisocyanate is selected from the group consisting of from 1-isocyanate-3-isocyanate-methyl-3,5,5-trimethylcyclohexane, Xylene diisocyanate, 3,3'-dimethyl-diphenylmethane-4,4'-diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, Methylene bis (4-cyclohexyl diisocyanate), hexamethylene diisocyanate, 1,5-naphthylene diisocyanate, meta-phenylene diisocyanate, meta-tetramethylxylene di-isocyanate, para-tetramethylxylene diisocyanate and Methylene bisphenyl diisocyanate. 9. The composition according to claim 8, characterized in that that they also have a Contains crosslinker.