Abstract: Two phenolic epoxy resins with different softening points F-51, JF-41 and acrylic acid were used as raw materials to synthesize two phenolic epoxy acrylates and further modified with maleic anhydride to prepare dilute alkali development Photosensitive resin. The effects of reaction temperature, catalyst type and catalyst dosage on the reaction were investigated. Use synthetic photosensitive resin to make photo-imaging solder resist ink, after screen printing, UV curing for 40s, good developability, curing at 140℃ for 30min, film hardness ≥ 4H, adhesion level 1, good solvent resistance, thermal decomposition Temperature ≥300℃.
Epoxy acrylic resin is the base resin of printed circuit board (PCB) photocurable, epoxy phenolic resin photoimageable solder resist ink [1-2]. The traditional heat-curing solder resist ink contains a lot of solvents, which is harmful to the environment. Today, as electronic materials become more and more fine and high-density, UV-curable solder resist and photosensitive imaging solder resist inks for PCB have gradually replaced traditional thermal curing Ink. The UV curable solder resist ink is mainly composed of epoxy acrylic photosensitive resin, photoinitiator, epoxy resin, curing agent, filler, thinner, etc., and the performance of the photosensitive resin directly determines the basic performance of the solder resist ink [3- 4]. Therefore, the development of new low-cost, high heat-resistant photosensitive resin has great practical significance.
In this study, two types of phenolic epoxy resins with different softening points were used to react with acrylic monomers to obtain epoxy acrylic resins, which were further modified with acid anhydrides to prepare alkali-soluble photosensitive resins. The photocuring and photosensitive imaging solder resist inks were made with synthetic photosensitive resins, and the curing properties, physical mechanical properties, thermal properties and solvent resistance of the inks were studied.
Epoxy resin F-51: industrial products, tin-free resin; epoxy resin JF-41 industrial products, Changshu Xinghua Pharmaceutical Auxiliary Co., Ltd.; acrylic acid (AA): chemically pure, Tianjin Kemeiou Chemical Reagent Development Center; Ma Maleic anhydride (MAn): analytically pure, Tianjin Chemical Reagent One; hydroquinone: analytically pure, Tianjin Damao Chemical Reagent; ethylene glycol acetate (CAC): Tianyin Chemical; tetraethylammonium bromide (MAn) TEAB): analytically pure, chemical reagent; tetrabutylammonium bromide (TBAB) analytically pure, Wulian Chemical; triethanolamine (TEAA): analytically pure, Lingfeng chemical reagents are limited; triphenylphosphine (TPP): analytically pure , Tianjin Kemeiou Chemical Reagent Development Center; initiator ITX, 907: Jingjiang Hongtai Chemical Co., Ltd.; reactive diluent tripropylene glycol diacrylate (TPGDA), trimethylolpropane triacrylate (TMPTA), isobornyl acrylate (IBOA): Changxing Chemical. UV-A photometer: Beijing Normal University photoelectric instrument; three-roll mill.
Weigh a certain amount of phenolic epoxy resin, dissolve it by heating with CAC, add it to a three-necked flask with a reflux condenser and stirrer, add the polymerization inhibitor and catalyst, heat to 110 ℃, and add it with a constant pressure funnel after constant temperature Quantitative acrylic monomers, controlled to drip within 1 hour, then stirred and reacted for several hours. The acid value of the system was measured at regular intervals, and the reaction was terminated when the acid value of the system was 5 or less to obtain phenolic epoxy acrylate (a). The reaction is shown in formula (1).
Reduce the temperature of the synthesized phenolic epoxy acrylate to 90~100℃, add a certain amount of maleic anhydride according to the amount of a certain amount of material, and raise the temperature to 110℃ to react for 2~3h. When the measured acid value of the system basically does not change, the reaction is ended to obtain the alkali The soluble anhydride-modified phenolic epoxy acrylate photosensitive resin (b) is represented by formula (1).
Measurement of epoxy value: Measured by hydrochloric acid-acetone method. Determination of acid value: accurately weigh a certain amount of sample to be tested, dissolve it in ethanol-acetone solution, add 2 drops of phenolphthalein indicator to epoxy phenolic resin epoxy phenolic resin, and titrate with the calibrated KOH solution 0·1mol/L Calculate the acid value based on the volume of the KOH solution consumed. Calculation of conversion rate: Conversion rate is calculated according to formula (2).
In equation (2): P is the conversion rate; initial acid value = amount of acidic substance × 56.1×1000/total mass of reactants.
Ultraviolet curing experiment: The light source is a 1000W UV iodine gallium lamp, 20cm away, and the surface drying time of the paint film is the curing time.
FT-IR analysis: The sample was coated on the potassium bromide tablet, and measured by Nicolet670 infrared spectrometer.
Determination of the degree of curing: expressed in terms of the gel content of the product. Coat the product with initiator and reactive diluent on the polyester film, form a film by exposure, weigh it and soak in acetone to completely dissolve the uncured components in acetone, remove and dry, Calculate the gel content according to formula (3).