IEEE TRANSACTIONS ON COMPONENTS AND PACKAGING TECHNOLOGIES, VOL. 26, NO. 3, SEPTEMBER 2003 569 Disk-Shaped Miniature Heat Pipe (DMHP) With Radiating Micro Grooves for a TO Can Laser Diode Package Hsin-Tang Chien, Da-Sheng Lee, Pei-Pei Ding, Shiu-Lin Chiu, and Ping-Hei Chen Abstract—A mounting base integrated with disk-shaped miniature heat pipe (DMHP) is designed for laser diode TO can package in the present study. The heat spreading performance of the disk-shaped miniature heat pipe is also presented. The present mounting base is made of aluminum (6061 T6) other than the conventional TO can package with oxygen free copper. The mounting base shows different thermal resistance with different working fluid charge volume. By optimizing the working fluid charge volume, the thermal resistance of the present mounting base will become lower than the conventional base with an oxygen free copper disk for TO can package. Moreover, this novel design can be manufactured on a massive scale and the fabrication cost can thus be effectively reduced. Index Terms—Heat spreader, micro groove heat pipe, TO can laser diode packaging. I. INTRODUCTION L ASER DIODES, known as semiconductor lasers, have been popularly used as light source in many applications such as laser pointer, CD ROM drive, laser printer, optical communication system, and bar code scanner. Laser diodes provide stable coherent light beam and are usually packaged in very compact forms. Therefore, high heat flux will be generated while emitting light in such compact volumes. Consequently, the temperature of laser diode might rise rapidly without proper application of cooling device that can effectively dissipate heat from the laser diode to the surrounding atmosphere. Temperature rise in the active region of a semiconductor laser diode can cause a significant impact on the laser beam character- istics. The wavelength tolerance of optical communication de- vice can be deeply affected by the large temperature change. If a laser diode is operated under a constant current condition, a tem- perature rise will cause a peak shift in the emitting wavelength of an approximate value of 0.2 nm/K and a decrease in output laser power of approximately 0.2 mw/K. The wavelength drift of the emitted light results in the mode-hopping phenomenon. Therefore, it is critical to control the laser diode’s temperature to assure the standard operation. The control on the laser diode’s temperature can be achieved by coupling an effective cooling device to the laser diode packages. The heat generation in a laser Manuscript received September 1, 2002; revised February 8, 2003. This work was recommended for publication by Associate Editor T. Lee upon evaluation of the reviewers’ comments. The authors are with the Mechanical Engineering Department, National Taiwan University, Taipei, Taiwan 10617, R.O.C. (e-mail: phchen@ntu.edu.tw). Digital Object Identifier 10.1109/TCAPT.2003.817648 Fig. 1. TO can package of a laser diode. diode is highly related with the material used, the ohmic contact, the confinement layer, laser stripe morphology, and packaging technology[1]. Various cooling devices such as heat spreader and heat sink have been proposed to control the laser diode’s temperature [2]. For a conventional TO can package of laser diode shown in Fig. 1, a copper disk is attached to the laser diode as a heat spreader due to its high thermal conductivity of 401 W/m-K. To avoid the oxidation of copper plate, the purity of copper disk for a TO can package is 99.999%. Miniature heat pipe (MHP) has become one of the best choices to dissipate heat generated by the chips in electronic equipments because of its low cost, compact size, passive operation, packaging flexibility, large thermal conductance, and high reliability. The application of MHP in improving heat dissipation rate on electronic devices can be dated to 1984 [3]. Many attempts have so far been proposed, especially on the wick structure of heat pipe, to obtain a greater capillary force to drive the flow of condensed coolant to evaporator in order to improve the thermal performance. Nevertheless, the cost of manufacturing these proposed wick structure should be considerably inexpensive and the reliability should be lies above an acceptable level for practical application in electronic devices. Hammel et al. [4] proposed a silicon heat spreader with microwhisker structure, which was proved to have a heat dissi- pation rate of 6 . Ponnappan [5] presented a miniature heat pipe with groove-wick structure. The evaporator heat flux of the design can be up to 115 with a thermal resistance of 0.16 K/W. Zuo et al. [6] developed a heat pipe with a closed serpentine loop in which the pulsating flow is thermally driven. The prediction showed that the cooling capacity could rise to 250 with a thermal resistance of 0.16 K/W. Both Take et al. [7] and Take and Webb [8] conducted measurements on the thermal performance of integrated roll bond heat pipe 1521-3331/03$17.00 © 2003 IEEE Authorized licensed use limited to: IEEE Xplore. Downloaded on October 22, 2008 at 02:53 from IEEE Xplore. Restrictions apply.