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If you have any oth­er ques­tions about the effects of time and tem­per­a­ture on the cure of epoxy mold­ing com­pounds please feel free to leave a com­ment below or don’t hes­i­tate to con­tact us. Please vis­it us at to learn more about our whole range of mold­ing com­pounds includ­ing our semi­con­duc­tor epoxy mold­ing com­pounds, indus­tri­al-grade fiber­glass-rein­forced epoxy mold­ing com­pounds, and opti­cal­ly clear epoxy mold­ing com­pounds (CMC) for opto­elec­tron­ics. Please stay tuned for the next part in this series to explore the behav­iour of epoxy mold­ing compounds. Mea­sur­ing this flow at dif­fer­ent times and tem­per­a­tures will there­fore give you the extent of this prop­er­ty change. The dif­fer­ence in min­i­mum achiev­able vis­cos­i­ty is dif­fer­ent depend­ing on the epoxy com­pound itself and the time and tem­per­a­ture that the epoxy was stored. The curve in Fig­ure 2 shows how the min­i­mum achiev­able vis­cos­i­ty is affect­ed after expo­sure to tem­per­a­ture for extend­ed peri­ods of time. This test mea­sures the vis­cos­i­ty of an epoxy mold­ing com­pound at a con­stant tem­per­a­ture, typ­i­cal­ly using the epoxy mold­ing tem­per­a­ture of 175☌. The min­i­mum achiev­able vis­cos­i­ty can thus be impor­tant to ensure that the parts are com­plete­ly encap­su­lat­ed and that there are no cas­es of incom­plete fill.Īn indus­try stan­dard test to mea­sure the vis­cos­i­ty is called a Shi­madzu vis­cos­i­ty flow test. Fail­ure to com­plete­ly encap­su­late the part is called “incom­plete fill”. This is an impor­tant step in the mold­ing process as it allows the epoxy to flow into the mold cav­i­ties and encap­su­late the device or com­po­nent before cur­ing to pro­vide strong mechan­i­cal pro­tec­tion. Shi­madzu vis­cos­i­ty test show­ing min­i­mum achiev­able viscosity This means that at con­tin­u­ous expo­sure to tem­per­a­ture, the vis­cos­i­ty will first drop to its min­i­mum achiev­able vis­cos­i­ty and then rise again as the epoxy cures until the epoxy stops flow­ing com­plete­ly. Unlike a ther­mo­plas­tic how­ev­er, epoxy mold­ing com­pounds are ther­moset plas­tics. At tem­per­a­ture and under pres­sure, the epoxy mold compound’s vis­cos­i­ty will drop sig­nif­i­cant­ly going from a sol­id at room tem­per­a­ture to a liq­uid when exposed to tem­per­a­tures of 160☌ to 200☌ under 1–2 bars of pres­sure. Dur­ing the trans­fer mold­ing or injec­tion mold­ing process, the epoxy is exposed to ele­vat­ed tem­per­a­tures and pres­sure.