Development Of Epoxy Resin Electronic Packaging Mold Cleaning Rubber

To clean the mold with mold cleaning rubbers(MCR)has become one of the main cleaning methods of epoxy resin packaging dies.The dirts of epoxy resin packaging mold has the characteristics of strong adhesion and difficult to be removed etc.,and the accumulation of these dirts on the mold surface will cause the surface defects of the electric elements,the difficulty of mold releasing and other problems and affect the quality of the elements.Compare to the traditional manual cleaning methods and the chemical soaking cleaning methods,MCR has the advantages of no need of mold disassembly,simple operation,little pollution,high efficient and excellent cleaning effect.However,so far,only very litttle reports have been reported on the developments of this kind MCRs and their evaluation methods.In this thesis,the evaluating methods of the effects of MCRs were studied.The mold cleaning process is first the release of the mold cleaning agent from MCRs,then these cleaning agents swelling or softening the dirts attached to the mold surface,and then these dirts were adhered by the MCRs and removed from the mold cavity.Therefore,the mold cleaning effects of MCRs would be evaluated by the releasing mechanism of the mold cleaning agents,the swelling degree of the epoxy resin in the mold cleaning agents,and the adhesion strength of the MCRs to the epoxy resin.The thermogravimetric(TG)characteristics of the mold cleaning agents and their dissolving and swlling capacities to the epoxy resins were studied with TG analysis,infrared spectroscopic analysis and swelling rate determination,these informations can be used as standard datas in MCR evaluations based on numerical values.It was proved that the mold cleaning agent had no obvious dissolution effect to the epoxy resins,the main effects were swelling.The n-methylpyrrolidone and benzyl alcohol had the largest swelling effects to epoxy resins,their equilibrium swelling ratio to black epoxy resins were 7.06% and 3.55% respectively.The type of the mold cleaning agents is one of the key factors affecting the mold cleaning effect.Meanwhile the MCRs formulations and the vulcanization conditions of MCRswere optimized in this paper.The effects of the rubber species,and the type and dosage of vulcanization system,the clear mold agents,the reinforcing filler,and the vulcanization conditions on the physical and mechanical properties,demoulding process properties and cleaning properties of the MCRs were studied as well.The results showed that when using NR/BR(1/1)as the base rubber and BIPB/TAIC(2/3)peroxides as curing agents can improve the adhesive strength and the escaping characteristics of the cleaning agents of the MCRs.Increasing the dosage of filling agent is also helpful to improve the effects of mold cleaning.When the MCRs wrer cured at 185℃ for 7.5 min,the MCRs have the best rubber stripping process index.The adhesion strength and the mold cleaning effect will be improved the curing time of MCRs was prolonged.