A Novel Thermodynamic Model and Temperature Control Method of Laser Soldering Systems

Table 3

Parameters involved in the model.

Symbol	Quantity	SI value
	Specific heat capacity of the paste before melting	230 kJ/kg/°C
	Specific heat capacity of the paste after melting	200 kJ/kg/°C
	Specific heat capacity of the pad	230 kJ/kg/°C
	Mass of the pad	kg
	Mass of the solder paste	kg
	Indoor temperature	25°C
	Area of the pad	m^2
	Laser absorptivity	0.77
	Geometrical factor	38.5
	Coefficient of heat conduction of the paste	401 W/m^2/°C
	Coefficient of convective heat transfer	10 W/m^2
	Melting temperature of the solder paste	172°C
	Maximum temperature of the laser soldering process	°C
	Temperature of the joint at time	°C
	Latent heat energy for melting solder	J/kg