电子元件的防静电损坏措施.htm

该资料时关于EMC的相关问题

      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>接地线</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="17%" style='width:17.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>C3</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>静电放电</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><br>
      </span><span style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:
      Arial;mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>接地设施</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="13%" style='width:13.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>C4</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>地</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="21%" style='width:21.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>C5</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>接地搭接点</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="17%" style='width:17.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>C6</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>大地</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><br>
      </span><span style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:
      Arial;mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>接地点</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
     </tr>
     <tr>
      <td width="16%" style='width:16.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>C7</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>手套</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="16%" style='width:16.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>C8</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>脚趾和</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><br>
      </span><span style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:
      Arial;mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>脚跟带箍</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="17%" style='width:17.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>D1</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>电离剂</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="13%" style='width:13.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>E1</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>工作面</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="21%" style='width:21.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>F1</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>腿和座套已</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><br>
      </span><span style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:
      Arial;mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>接地的转椅</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="17%" style='width:17.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>G1</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>人体接</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><br>
      </span><span style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:
      Arial;mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>地地板</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
     </tr>
     <tr>
      <td width="16%" style='width:16.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>H1</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>工作服</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="16%" style='width:16.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>H2</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>工作帽</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="17%" style='width:17.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>I1</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>具有接地</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><br>
      </span><span style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:
      Arial;mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>面的搁板</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="13%" style='width:13.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>I2</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>接地机架</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="21%" style='width:21.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>J1</span><span
      style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:Arial;
      mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>静电放电</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><br>
      </span><span style='font-size:9.0pt;font-family:宋体;mso-ascii-font-family:
      Arial;mso-hansi-font-family:Arial;mso-bidi-font-family:Arial'>保护区标志</span><span
      lang=EN-US style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
      <td width="17%" style='width:17.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span style='font-size:
      9.0pt;font-family:宋体;mso-ascii-font-family:Arial;mso-hansi-font-family:
      Arial;mso-bidi-font-family:Arial'>　</span><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
     </tr>
    </table>
    </div>
    <p style='margin-bottom:0cm;margin-bottom:.0001pt'><span style='mso-bidi-font-family:
    Arial'>　　典型的静电放电保护区如图<span lang=EN-US>1所示，此图摘自EN100015-1，其中许多是新近的。该图给出了各种可能的措施，但并没有必要全部使用这些措施，这主要由特定的环境决定。所采用的其本原理就是等电位搭接，即将所有表面连接在一起，防止不同物体之间产生电位差。<br>
    　　工作面[E1]是静电损耗性的，通过静电放电的接地设施[C3]连接到地[C4]。工作站的操作人员通过导电腕[C1]上的导线和地电位点相连，然而，对于活动频繁的人员，最好是通过脚跟和脚趾带箍[C8]与静电损耗地板[G1]相通（即接地）。腕套的接地导线在接地点[C5]处进行端接。<br>
    　　操作人员所穿的破旧工作服[H1、H2]也应是静电损耗性的，并在靠近静电放电敏感元件附近遮住工作人员自己的衣服，所有破旧的手套也应是导电材料的。<br>
    　　转椅[F1]不应视为操作人员接地的基本方法，但值得注意的是，转椅上必须铺一层抗静电的材料，使座套、靠背和扶手均有与地相通的路径。<br>
    　　元件应存放在带有接地面的搁板[I1]上，或者是接地的机架[I2]上。这些东西与工作台都应通过接地导线[C2]与静电放电的地面相接。<br>
    　　当用手推车装运元件或子配件时，其表面导电性能应与工作面和导电机架的导电性能相似。如果接地轮[A1]导电性良好，且与手推车车架电气连接，那么不再需要使用接地滑片了。如果EPA的地板没有接地，那么当手推车停下来装卸东西时，则应将其接地点[C6]与大地接地点[C5]相连。<br>
    　　在操作人员的正常工作期间，对所采用的这些措施的效果应该用静电伏特计测量其静电势和静电场来评估。<br>
    在保护区内和进出口处，应使用标志[J1]来提醒他们注意。<br>
    　　应对腕套及其接地导线用导通测试仪定期进行检测。导电轮和脚趾带箍也应作类似的检测[B2，B3]。<br>
    <br>
    ５．安全性<br>
    　　EPA内一般有加电的工具和设备。在这种环境中，将单个物件或设备直接连接到地是很危险的。正是由于此原因，腕套接地导线、转轮及脚趾带箍的连接处均要串入一只不低于1M的电阻。有些腕套接地导线的每端均有一只这样的电阻，因此，即使腕套接地导线接在加电维修的产品的带电接线端，也不会有危险。<br>
    &nbsp;&nbsp;&nbsp; 腕套接地导线测试仪是一种检测电阻的阻值是否合适（如果太高 ，不可能实现等电势搭接；如果太低，会出现安全危害）的仪器。<br>
    　　腕套接地导线要配以可快速拔下的与其它电气插座不兼容的插头，这样可以保证它不会误插到其它电气插座上，并且，在紧急情况下容易拔下。<br>
    <br>
    ６．静电放电保护区内的实际工作<br>
    <br>
    　　在静电放电保护区内，如果不遵守明确的工作规范，电荷和电势就不能保持在允许的范围内。一些会导致问题的例子包括：将装在不抗静电的塑料封面内的文件、塑料容器、杯子等带进静电放电保护区内，使用会破坏地板或工作表面静电特性的清洁剂。<br>
    　　有关人员应接受足够的训练，不仅学习需要遵守的规程，还要了解必须遵守这些规程的理由。了解可能损坏的元件的有关参数也是有用处的。<br>
    　　应指定专人负责静电放电保护区的保养与维护，同时还要对规程的执行情况进行检查。这些检查也应作为质量管理体系认证的一部分加以核查。<br>
    <br>
    ７．运输与存放<br>
    　　运输带引脚的元件时，通常使用导电泡沫材料。这可以防止元件引脚间出现较高的电势差，对于双列直插式封装的元件，在散装运输过程中常采用静电损耗性管。<br>
    　　对于线路板组件，当位于静电放电保护区外时，应将其置于静电屏蔽袋或导电搬运箱内进行运输。有的包装袋使用导电材料制成，它可确保所有元件在稳定条件下处于同一电势，同时将偶然跑到袋上的静电荷耗散掉。这种方法不能用于带电池的电路板，对于这种情况，应采用衬里是静电损耗性材料的，而外层是导电材料的包装袋。这种袋子的价格更高，但可对加电和未加电的组件提供极好的保护作用。同样，内部装有固定电路板的导轨的导电箱不能与边缘上有裸露连接器的加电电路板一起使用。<br>
    <br>
    ８．现场维修<br>
    　　现场需要维修的产品上要设置一个静电连接点，这样，维修技术人员在打开设备的盖子之前，可以将腕套的接地导线连上。备件应放在静电屏蔽袋或箱子中进行运输，除非备件中不包含静电放电敏感元件。如果模块工作在暴露状态下，应将静电损耗性地板垫连接到产品的静电搭接点上，作为工作面使用。<br>
    <br>
    ９．有关标准<br>
    　　1987年，英国进行了将实践规程编制成文件的第一次尝试，其成果是BS5783。与其说这是一个关于应该进行哪些检测的标准，更不如称其为一个实践规范条款。这项工作的第二阶段是将这个标准转换欧洲组织中的一个规范，其编号是CECC
    000151，其标题为：“基本规范：静电敏感元件的保护第一部分：总体要求”。该标准1991年出版，1992年重新编号为EN 1000151。其它部分在1993年（第二部分：低湿度条件要求）和1994年（第三部分：清洁区要求，第四部分：高压环境要求）出版。这些部分的内容超出本文讨论范围。<br>
    　　标准不仅包括安装、维护和检验本文所述的措施方面的要求，而且也详细阐述了包括测试方法在内的静电保护器件自身的详细要求。<br>
    　　技术和工艺的不断发展和执行标准中积累的经验，以及自动化机械设备的普遍使用，使这些标准得到不断完善，包括使其结构更加合理化，同时将用户指南从标准化版本中分离出来。修订工作已纳入国际电工委员会所组织的国际论坛中，新制定的标准将在IEC
    1340系列中发布，毫无疑问，这与欧洲标准是相辅相成的。有关标准部分如表2示：<o:p></o:p></span></span></p>
    <p align=center style='margin-bottom:0cm;margin-bottom:.0001pt;text-align:
    center'><span lang=EN-US style='mso-bidi-font-family:Arial'><br>
    表2 国际电工委员会1340方案结构<o:p></o:p></span></p>
    <div align=center>
    <table border=1 cellspacing=0 cellpadding=0 width="51%" style='width:51.0%;
     mso-cellspacing:0cm' bordercolordark="#ffffff" bordercolorlight="#000000">
     <tr>
      <td width="100%" colspan=2 style='width:100.0%;padding:.75pt .75pt .75pt .75pt'>
      <p align=center style='text-align:center'><span style='mso-bidi-font-family:
      Arial'>表<span lang=EN-US>2&nbsp;&nbsp; 国际电工委员会1340方案结构<o:p></o:p></span></span></p>
      </td>
     </tr>
     <tr>
      <td width="35%" style='width:35.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>IEC 1340-1<o:p></o:p></span></p>
      </td>
      <td width="65%" style='width:65.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span style='font-size:
      9.0pt;font-family:宋体;mso-ascii-font-family:Arial;mso-hansi-font-family:
      Arial;mso-bidi-font-family:Arial'>概要</span><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
     </tr>
     <tr>
      <td width="35%" style='width:35.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'>IEC 1340-1-1<o:p></o:p></span></p>
      </td>
      <td width="65%" style='width:65.0%;padding:.75pt .75pt .75pt .75pt'>
      <p class=MsoNormal style='line-height:14.0pt'><span style='font-size:
      9.0pt;font-family:宋体;mso-ascii-font-family:Arial;mso-hansi-font-family:
      Arial;mso-bidi-font-family:Arial'>静电原理指南</span><span lang=EN-US
      style='font-size:9.0pt;font-family:Arial'><o:p></o:p></span></p>
      </td>
     </tr>
     <tr>
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