Thermal solutions to Pentium processors in TCP in notebooks and sub-notebooks

Less than one year after the introduction of the 90 MHz Pentium Processor in Pin Grid Array (PGA) package, 75 MHz Pentium Processor in Tape Carrier Package (TCP) has been introduced for applications in mobile products. Notebooks and sub-notebooks using the 75 MHz Pentium Processor in TCP are expected to be on the market early 1995. In this paper, we will review the various thermal enhancements from the component, board and system level for the use of the Pentium processor in TCP in notebooks and sub-notebooks. The thermal tests are conducted in one reference notebook and sub-notebook using test boards and thermal test die. Thermal characterizations of the TCP find that with 4 Watts of board power, the TCP can dissipate up to 3.55 Watts of CPU power in the reference notebook and 2.71 Watts in the reference sub-notebook. Various thermal enhancements such as heat sinks, metal plates, are evaluated in the reference notebook. For the design target of 6.5 Watts of CPU power, four solutions are proposed for the reference notebook: the heat sink and aluminum plate solution, heat pipe connected to the keyboard solution, heat pipe connected to the outside aluminum plate solution and fan/heat sink solution. Two solutions are proposed for the reference sub-notebook: the heat pipe connected to the keyboard solution and heat pipe on the bottom chassis solution. Although the study is conducted in the reference notebook and sub-notebook, the thermal design trade offs and relative cooling capabilities are applicable to the general notebook and sub-notebook thermal designs.