This paper discusses the development and use of an approximate analysis model for predicting the temperature distribution on a Printed Circuit Board (PCB) containing imbedded heat dissipating electronic components which are being cooled by laminar air flow induced by a fan. The direction of the air flow is parallel to the PCB. Temperature results obtained from the model are presented in dimensionless curves as a function of the PCB design parameters including the board dimensions, air velocity (or flowrate), and number, position and heat dissipation of the components. These curves enable the engineer to quickly select the optimal values of the design parameters which meet the design specification imposed on the maximum allowable board wall temperature. Information gained from these curves is employed to establish a set of guidelines (steps) for the preliminary thermal design and layout of the PCB and components.