Research On Solvent Method's Layered Dissociation Of WPCBs

As emerging technology rapidly develops,updating rate of electronic products constantly speeds up.PCB as carrier in electronic components,and waste accumulation shows an increasing trend.Nowadays,discarded circuit board containing mass of metals and non-metal elements is an ignorant“Urban Mines”.Its high-efficient recycling means has already gradually taken place by the burning buried fill.The paper mainly makes FR-4 glass fiber copper clad sheet as research object and builds a new technology dissociating metal and nonmetal based on the solvent method.?1?It can be informed that discarded circuit board is a kind of layered structure bonded by bonding agent by analysis of truncation morphology and metallography.Discarded circuit board is compressed by cooper foil,resin and glass fiber.After components of Discarded circuit board is analyzed and calculated,it's gotten that one-dimensional solubility parameter?_Small=22.69?J/cm³?^1/2,?_Fedor=21.79?J/cm³?^1/2,three-dimensional solubility parameter?_d=19.08?J/cm³?^1/2,?_p=11.02?J/cm³?^1/2,?_h=11.05?J/cm³?^1/2.?2?Based on soluble inflation and layered experiment,it has chosen good solvent used to layered dissociation experiment:N,N-Diethylformamide.In the meanwhile,it can be confirmed the important parameters of layered dissociation from glass-transition temperature by analyzing different solvents'result in layered dissociation experiment.?3?After that,by making use of DEF,as test solvent,it ensures the perfect experiment parameters of discarded circuit board‘s layered dissociation process:heatingtemperature150?,ratiobetweendiscardedcircuitboardand N,N-Diethylformamide solid solution 1:5,size of discarded circuit board 1×1cm².After the recycling metal and nonmetal components are tested and analyzed,it can be ensured that both glass fiber and copper foil can be input to reproduce,which realizes its recycling.Used solvent is processed that achieves solvent recycling.?4?Swelling experiment analyzes by making use of synthetic resin that swelling in layered dissociation experiment stems from swelling phenomenon of solid resin,which validates temperature's influence on swell and the layered dissociation of discarded circuit board takes place when it reaches TG temperature.It has confirmed dynamic model of swelling process by analyzing relation between swelling time and swelling extent.?5?It's gotten mechanics of layered dissociation discarded circuit board through its swelling curve,truncated morphology change before and after,infra-red spectrum change and thermal stability change.This is because:?a?resin swelling enables layered gap and distance becoming large in thermal process,which makes solvent further penetrating discarded circuit board.?b?after temperature reaches TG,move of layered resin increases.Resin structure's gap increases,which makes solvent molecule invades.It has destroyed stability of three-dimensional network structure and lowered resin's adhesive,which makes copper foil and glass fiber further dissociate.?c?solid resin in the structural linear molecule,under reaction of solvent circumstances,solves solvent in the form of the whole.Resin's stability is further weakened,which weakens gradual dissociation between copper foil and glass fiber.The best mix is 80%DEF+20DMF.