Thermal Expansion and Hydration Behavior of PMMA Moulding Materials for LIGA Applications

The thermal expansion coefficient, swelling characteristics and solute uptake kinetics of three PMMA molding materials (Perspex-CQ, Acrylite OP-1 and Solacryl 2750) are reported. Over the temperature range of 22 C to 50 C, all three materials exhibited similar CTE values of approximately 7.5 x 10{sup -5} C{sup -1}. Swelling characteristics, measured as the change in length of coupons were examined in three environments: deionized water, Ni Sulfamate plating solution and Ni Watts plating solution. Total swelling after {approx}150 hours of exposure was similar for all materials in each environment but were different for each environment examined: {approx}0.42% for de-ionized water, {approx} 0.30% for the Ni Sulfamate and {approx} 0.36% for the Ni-Watts plating solutions. Solute uptake kinetics were measured between 4 C and 50 C and the pre-exponential term (D{sub o}) and the activation energy (QD) are reported for each material in the three environments. Do values ranged between 0.07 and 0.45 cm{sup 2}/sec depending on the environment. Q{sub D} showed little variation, ranging between 4.1 and 4.4 x 10{sup 5} J/mole