PCB Trace Thermal Analysis and Effective Conductivity

Abstract

The electrical current carrying capability of a surface or buried trace located within a fiberglass printed circuit board (PCB), is of important interest in the microelectronics industry. The maximum allowable trace power, hence local integrity and maximum allowable operating temperature, will depend on several parameters including the circuit board thermal conductivity, thickness, trace size and location. A two-dimensional, steady-state thermal conduction analysis is made on a finite, plane homogeneous medium (PCB), to examine the trace behavior. The trace is modeled as a zero-thickness, strip heat source with specified uniform temperature, and it’s position in the medium is varied. A two-dimensional thermal analysis is also performed on a multilayered cell model with finite heat source, to establish an accurate, effective thermal conductivity for a typical PCB. Results are tabulated and presented graphically for both the two-dimensional trace and effective conductivity models.