Stresses curing conditions

The method for mathematically simulating the cure process is as follows First, compute the layer stresses in moving from installation to cure conditions, assuming that all materials are perfectly elastic. The resulting stresses are examined, and the layers that appear to be under tensile stresses and which contain swellable materials are noted. These are the layers that will swell during cure to neutralize the tension. 

The cure conditions used for passivation of the Ni/Fe devices were a vacuum oven bake at 220° C for 3 hours. The 220° C was reached in a programmed mode to avoid thermal stress on the substrates. ... 

Polyimides Higher temperature stability compared to epoxies. High ionic purity. Reduced bleedout. Trapped solvent can produce voids under large ICs. Multi-step curing required to volatilize solvent. High-stress materials. May absorb moisture in cured condition. Cannot be B-staged. 

The die is rrsrrally between 0.5 m and 1.5 m long. The polymeric matrix is cured at temperatures that mostly range from 90"C to 180°C, and depend on the resin system used (among other factors). The proper definition of temperatures at different locations along the die helps to optimise curing conditions and prevents thermal residual stresses from developing. 

Fatigue strength is dependent on adhesive, curing conditions, joint geometry, mode of stressing, magnitude of stress, and duration and frequency of load cycling. 

The difference in the heat expansion coefficients of E-glass and UP resin creates additional stresses in the component interfaces. The same process takes place when fiber composites are post-cured. Therefore, post-curing conditions have to be selected so that local crack formation is avoided when resin and reinforcing materials are not evenly distributed. 

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