主要内容主要内容 一、一、基本概念基本概念 二、降额设计一般原则二、降额设计一般原则 三、降额设计工作过程三、降额设计工作过程 四、降额设计示例四、降额设计示例 五、各类元器件降额简述五、各类元器件降额简述 六、元器件降额设计要求六、元器件降额设计要求 一、基本概念一、基本概念 电子产品的降额设计就是使元器件或设备在使电子产品的降额设计就是使元器件或设备在使 用中所承受的应力（电、热、和机械应力等）低用中所承受的应力（电、热、和机械应力等）低 于其额定值的方法。于其额定值的方法。 修改电路设计（余度设计、热设计）修改电路设计（余度设计、热设计）→→使元器件使元器件 所承受的应力降低所承受的应力降低→→需要整体考虑、综合权衡；需要整体考虑、综合权衡； 合理选用元器件品种、规格合理选用元器件品种、规格→→使得所选元器件的使得所选元器件的 额定值高于工作中要承受的应力额定值高于工作中要承受的应力→→需要考虑费用、需要考虑费用、 尺寸、重量的约束。尺寸、重量的约束。 基基 本本 方方 法法 一、基本概念一、基本概念 通过限制元器件所承受的应力，使通过限制元器件所承受的应力，使 元器件在低于额定值情况下工作，降元器件在低于额定值情况下工作，降 低元器件失效率，提高使用可靠性；低元器件失效率，提高使用可靠性； 若元器件一直工作在额定应力值下，若元器件一直工作在额定应力值下， 其性能退化速率较快，因此降额使用其性能退化速率较快，因此降额使用 有利于延缓和减小性能退化；有利于延缓和减小性能退化； 使得设计具有一定安全余量，提使得设计具有一定安全余量，提 高系统的可靠性。高系统的可靠性。 降降 额额 设设 计计 的的 目目 的的 一、基本概念一、基本概念 ————降额可降低元器件失效率降额可降低元器件失效率 金属膜电阻器基本失效率（额定温度125℃）10-6/h金属膜电阻器基本失效率（额定温度金属膜电阻器基本失效率（额定温度125125℃）℃）1010 --66//hh TTSS ℃℃0.10.10.20.20.30.30.40.40.50.50.60.60.70.70.80.80.90.91.01.0 000.0020.0020.0020.0020.0020.0020.0030.0030.0030.0030.0030.0030.0030.0030.0030.0030.0040.0040.0040.004 10100.0020.0020.0030.0030.0030.0030.0030.0030.0030.0030.0030.0030.0040.0040.0040.0040.0040.0040.0050.005 20200.0030.0030.0030.0030.0030.0030.0030.0030.0040.0040.0040.0040.0040.0040.0050.0050.0050.0050.0050.005 30300.0030.0030.0030.0030.0040.0040.0040.0040.0040.0040.0040.0040.0050.0050.0050.0050.0060.0060.0060.006 40400.0030.0030.0040.0040.0040.0040.0040.0040.0050.0050.0050.0050.0050.0050.0060.0060.0060.0060.0070.007 50500.0040.0040.0040.0040.0050.0050.0050.0050.0050.0050.0060.0060.0060.0060.0070.0070.0070.0070.0080.008 60600.0040.0040.0050.0050.0050.0050.0050.0050.0060.0060.0060.0060.0070.0070.0080.0080.0080.0080.0090.009 70700.0050.0050.0050.0050.0060.0060.0060.0060.0070.0070.0070.0070.0080.0080.0090.0090.0090.0090.0100.010 80800.0050.0050.0060.0060.0060.0060.0070.0070.0080.0080.0080.0080.0090.0090.0100.0100.0110.0110.0120.012 90900.0060.0060.0070.0070.0070.0070.0080.0080.0090.0090.0090.0090.0100.0100.0110.0110.0120.0120.0130.013 1001000.0070.0070.0070.0070.0080.0080.0090.0090.0100.0100.0110.0110.0120.0120.0130.0130.0140.0140.0150.015 1101100.0080.0080.0080.0080.0090.0090.0100.0100.0110.0110.0120.0120.0130.0130.0150.0150.0160.0160.0180.018 1201200.0080.0080.0090.0090.0100.0100.0110.0110.0120.0120.0140.0140.0150.0150.0170.0170.0180.0180.0200.020 1301300.0090.0090.0100.0100.0120.0120.0130.0130.0140.0140.0160.0160.0170.0170.0190.0190.0210.021 1401400.0110.0110.0120.0120.0130.0130.0140.0140.0160.0160.0180.0180.0190.019 1501500.0120.0120.0130.0130.0150.0150.0160.0160.0180.018 1601600.0130.0130.0150.0150.0160.016 1701700.0150.015