Qualification/life testing was performed by subjecting test boards to the environmental harsh temperature extremes and assessing any structural failures, mechanical failures or degradation in electrical performance solder-joint failures due to either overstress or thermal cycle fatigue. The test boards of reflowed and reworked CCGA packages (717 Xilinx package, 624, 1152, and 1272 column Actel Packages) were selected for the study to survive three times the total number of expected temperature cycles resulting from all environmental and operational exposures occurring over the life of the flight hardware including all relevant manufacturing, ground operations, and mission phases or cycles to failure to assess the life of the hardware. The life testing of CCGA electronic packages under extreme thermal environments (for example: -185Â☌ to +125Â☌) has been performed with reference to various JPL/NASA project requirements which encompass the temperature range studied. The reliability of reworked/ reflowed surface mount technology (SMT) packages is very important for short-duration and long-duration deep space harsh extreme thermal environmental missions. Life testing/qualification of reflowed (1st reflow) and reworked (1st reflow, 1st removal, and then 1st rework) advanced ceramic column grid array (CCGA) surface mount interconnect electronic packaging technologies for future flight projects has been studied to enhance the mission assurance of JPL-NASA projects. Life testing of reflowed and reworked advanced CCGA surface mount packages in harsh thermal environments The presented method may be a promising approach in rapidly fabricating high quality aspheric microlens with complex surface. Results showed that the obtained aspheric MLA was good in both shape accuracy and surface quality. Fabrication of a designed aspheric MLA with this method was demonstrated in experiments. Different from the normal process, the reflow process here is investigated to improve the surface quality while keeping the pre-modeled shape unchanged, and thus will avoid the difficulties in generating the aspheric surface during reflow. Then the pre-shaped aspheric microlens is polished by a following non-contact thermal reflow (NCTR) process. And the dose modulation mainly depends on the distribution of exposure dose of photoresist. In this method, the complex shape of aspheric microlens is pre-modeled via dose modulation in a digital micromirror device (DMD) based maskless projection lithography. Huang, Shengzhou Li, Mujun Shen, Lianguan Qiu, Jinfeng Zhou, YouquanĪ novel fabrication method for high quality aspheric microlens array (MLA) was developed by combining the dose-modulated DMD-based lithography and surface thermal reflow process. It is believed that the application of resist containing crosslinker and optimized process conditions for smaller contact hole patterning is necessary for the mass production with a design rule below 130nm.įabrication of high quality aspheric microlens array by dose-modulated lithography and surface thermal reflow The introduction of two-step baking method for reflow process showed uniform CD value, also. The application of lower coating thickness of resist induced symmetric pattern profile even at edge with wider process margin. And also, it showed stable CD uniformity and improved resist properties for top loss, film shrinkage and etch selectivity. From the experiment results, it was confirmed that the effect of crosslinker in resist to reflow properties such as reflow temperature and reflow rate were very critical and it controlled the pattern profile during reflow processing. And several process conditions like resist coating thickness and multi-step thermal reflow method have been also evaluated to stabilize the pattern profile and improve CD uniformity after reflow process. In this paper, we have investigated the effects of chemical characteristics such as molecular weight, blocking ratio of resin, cross-linker amount and solvent type with its composition to reflow process of resist and found the optimized chemical composition for reflow process applicable condition. Therefore, shrinking technology using thermal reflow process has been applied for smaller contact hole formation. With the shrunken device rule below 130nm, the patterning of smaller contact hole with enough process margin is required for mass production. Kim, Myoung-Soo Park, Jeong-Hyun Kim, Hak-Joon Kim, Il-Hyung Jeon, Jae-Ha Gil, Myung-Goon Kim, Bong-Ho Reflow process stabilization by chemical characteristics and process conditions
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