Research And Application Of High Temperature Resistant Organic Solderable Protectives(HT-OSP)

With the rapid development of printed circuit board(PCB)and electronic mounting technology,electronic products and their mounting technology require PCB board surface treatment technology with high temperature solderability,lead-free,halogen-free characteristics.Organic Solderable Protection(OSP)has become a research hotspot in the field of PCB surface treatment technology due to its mature technology,low cost,and environmental protection.However,the heat resistance of the OSP film formed on the copper surface of the fourth-generation OSP products represented by alkylbenzimidazole compounds is not good,it is difficult to withstand multiple high-temperature thermal shocks,and the gold surface is prone to appear in actual production.Therefore,this paper developed an HT-OSP product with high temperature resistance,good oxidation resistance and excellent copper-gold selective deposition.This paper takes 2-[(2,4-dichlorophenyl)methyl]-1H-benzimidazole as the main film-forming substance,independently developed the HT-OSP bath formulation.The effects of HT-OSP treatment process parameters and the concentration of component formulations on HT-OSP film-forming performance were studied,and the best formulation and treatment process parameters were obtained.The effects of treatment time,solution pH,and main film-forming substance concentration on the thickness of the HT-OSP film layer were explored.The HT-OSP solution of the system has good stability,convenient management and control,and the prepared HT-OSP film has uniform and dense thickness and excellent performance.The mechanism of HT-OSP film formation was explored by quantum chemical calculation and molecular dynamics simulation,the results of quantum chemical calculations indicate the reactive sites of 2-[(2,4-dichlorophenyl)methyl]-1Hbenzimidazole compounds,the stability of imidazole compound-Cu(?)and imidazole compound-Cu(?),the stability of imidazole compound-Cu(?)is better than that of imidazole compound-Cu(?),The stronger the electrostatic interaction between the imidazole compound-Cu(?)and the copper surface,the easier it is to adsorb on the copper surface and form a film.Molecular dynamics simulations calculated the adsorption energy of imidazole compound-Cu(?)and imidazole compound-(?).The adsorption energy of imidazole compound-Cu(?)is-5.04 kcal/mol,and the adsorption energy of imidazole compound-(?)is-231.58 kcal/mol.The results show that the interaction of imidazole compound-Cu(?)with copper surface is stronger,it is easier to adsorb,which is beneficial to the formation of organic solderable protective film.The structure of the HT-OSP film layer was analyzed by XPS,and the existing form of copper in the OSP film layer was studied.Combining the results of quantum chemical simulation and molecular dynamics simulation,the film formation mechanism of high temperature resistant organic solderable protective agent was reasonably speculated.The various characterizations have shown that the HT-OSP film prepared by the above formula has good performance,and has excellent selectivity for copper and gold mixed printed circuit boards,which is superior to the mainstream commercial OSP.The thermogravimetric analysis and high temperature reflow soldering test results show that the organic protective film has good heat resistance.Under 300 ? high temperature environment,the HT-OSP film can withstand five high temperature thermal shocks;The results of electrochemical test and infrared test show that the organic protective film has good oxidation resistance and can be stored at room temperature for more than half a year;The results of edge immersion tin test and welding bond strength test show that the organic protective film layer has good solderability.