Advance Technique on the Baking Oven for Moisture Sensitive Devices

• Main Authors: Liang,Yijui, 梁益瑞
• Other Authors: Chang,Yun
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/01431813637868230176

碩士 === 國立聯合大學 === 機械工程學系碩士班 === 99 === The purpose of this research was to improve the present baking oven. The distribution of the air flow in the chamber of the present baking oven is extremely non-uniform on the cross section of the chamber. The insulation at the joint between the door and oven body of the present baking oven cannot sufficiently insulate heat leakage so that the temperature near the edge of the door may rise to a dangerous level. Control the moisture level of moisture sensitive devices (MOD) is very important to SMT process. If the floor-life (JEDEC) of the device is done the device should be put into the baking oven and remove the moisture before reuse. However, the poor uniformity of the baking air flow may lead to inconsistent baking quality of a batch of baking devices. This study investigated how the inner air flow of the baking oven can be modified by the geometry of settling chamber of the baking oven. The geometries of the settling chambers studied in this work were: without any perforated plate, with one perforated plate (present design) and with two perforated plates (one diagonal perforated plate). The simulation result from finite element analysis and experimental result both indicate that the air flow of the present baking oven is much non-uniform and a large vortex exists in the lower chamber. The result also shows that adding a diagonal perforated plate in front of the perforated plate at the intake of the baking chamber can eliminate the vortex and makes the air flow much uniform. The horizontal trays can guide the air flow and divide the vortex into two smaller vortices. The construction of insulation of the oven had been redesigned to reduce the surface temperature near the junction between the door and oven body. The computed result showed the temperature raise is only around 1℃ for the new design. A prototype with similar construction can makes a raise of the surface temperature around 2℃. This study also tried to combine a baking oven with dehumidity equipment in order to prevent the adsorption of the moisture from the air inside the oven. A thermo-control valve for switching the air flow between a heating unit and dehumidify unit was designed and tested. This valve is driven by a shape-memory alloy element and can automatically close at a temperature above 60℃.