| White solder resist ink is a kind of liquid photosensitive solder resist ink,is used in the electronic circuit board on a special function of permanent protective film,the protective film can prevent the oxidation of the PCB copper surface,prevent moisture,solvent corrosion and abrasion,and at the same time can enhance electronic circuit between electric insulation performance of the entire board face,so as to prolong the service life of the printed circuit board.Ink components for the main resin that alkali soluble resin,photoinitiator,active diluent,pi gment fillers and other additives,etc.,alkali soluble resin is the main component,its performance affects the mechanical and thermal properties of UV curing resistance ink.In view of this situation,this paper has carried out the research on the prepar ation of high reflective and high heat resistant double curing white welding resistance ink,which is mainly divided into two aspects.Part I: a alkali soluble resin for double curing white welding inks was synthesized by modification of acrylic acid and m aleic anhydride using phenolic epoxy resin as raw material.The alkali soluble resin has good heat resistance and mechanical properties.This part focuses on the study of the synthesis conditions of alkali soluble resin,including catalyst,polymerization inhibitor,reaction time,reaction temperature and so on.The best catalyst for the reaction was tetraethyl ammonium bromide and the dosage was 3%.The inhibitor was p-hydroxy phenyl methyl ether,and the optimal dosage was 0.3%.The catalyst was first dis solved in acrylic acid and then slowly dropped into epoxy resin.The optimal reaction time was4.5h,the temperature was 95℃,the optimum molar ratio of epoxy resin to acrylic acid was 1:0.8,and the golden color phenolic epoxy acrylic acid resin with acid value of 3.5Mg KOH /g was obtained.The molar ratio of epoxy resin to anhydride was 1:0.7,the reaction time was 3h,the best reaction temperature was 105 ℃,the light yellow photosensitive base-soluble phenolic epoxy acrylic acid resin was obtained,the acid value of the resin was 61.2 mg KOH/g,the hydroxyl value was10.1 mg KOH/g,the viscosity was 14325 mpa.s,the solid content was 82.3%.Part II: A high reflective double curing white resistance welding ink was prepared with phenolic epoxy alkali soluble re sin as the main resin.The effects of curing agent,active diluent,photoinitiator and resin acid value on the properties of ink were studied.Studied through contrast experiment of three different curing agent amino resin,TGIC(different cyanuric acid th ree glycidyl ester)and acid anhydride resin curing effect,be determined by the performance of the ink in the process of thermosetting ink curing agent choose anhydride curing agent,alkali soluble resin and fillers mix into A paste(part A),curing agent(component B)ratio of 3:1,the ratio of alkali soluble ink’d better and not easy yellowing occurred;TMPTA was selected as the active diluent.The dosage was 12%,and the hardness of the cured film could reach 6H.The photoinitiator was combined with TPO and 184,and the dosage was 6%.The influence of acid value on ink reflectivity and thermal stability was further studied.It was found that when the acid value of alkali soluble resin was controlled at 60 mg KOH/g,the ink film obtained had high reflectiv ity,gloss was up to 95%,and decomposition temperature was up to 496 ℃.The pigment chosen was titanium dioxide at a ratio of 25% and the filler was barium sulfate at a ratio of 15%.The performance test of the white resistance welding ink prepared by the ink formula studied in the second part was as follows: the ink viscosity measured by VT--04 F viscosity method(25℃)was 16925.1Mpa.s.The ink sample prepared by screen printing was uniform in color and had no bubbles and white spots on the surface.The film was completely dry and non-stick at 120℃ for 10 min.The ink film was alkaline washed in 3% Na2CO3 aqueous solution.The measured results showed that the surface and holes of the film were clean and the patterns were not excessive.The film was heated at 160℃ for 1h,and the surface of the film was wiped without change for more than 100 times with acetone,indicating that the ink was completely cured.After curing,the adhesion of coating film is 0,the hardness of pencil is 6H,the gloss of the ink at an Angle of 60° is 95.8%,and the image of window and human figure can be fully and clearly reflected under natural light.The solder was tested at288℃/10 s and the coating was qualified.Soaked in 10%H2SO4 solution and10%Na OH solution for 30min(25℃)respectively,the film’s acid resistance and alkaline resistance were measured by the tape stripping test.In addition,propylene glycol methyl ether acetate was used as solvent,the solvent resistance of the ink was good. |
PDF Full Text Request