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电子元器件布局基本规则
元器件布局对电路性能有一点的影响,羽凌教你如何布局电子元器件的基本规则 

1. 按电路模块进行布局,实现同一功能的相关电路称为一个模块,电路模块中的元件应采用就近集中原则,同时数字电路和模拟电路分开 

2.定位孔、标准孔等非安装孔周围1.27mm 内不得贴装元、器件,螺钉等安装孔周围3.5mm(对于M2.5)、4mm(对于M3)内不得贴装元器件。 

3. 卧装电阻、电感(插件)、电解电容等元件的下方避免布过孔,以免波峰焊后过孔与元件壳体短路。 

4. 元器件的外侧距板边的距离为5mm。 

5. 贴装元件焊盘的外侧与相邻插装元件的外侧距离大于2mm。 

6. 金属壳体元器件和金属件(屏蔽盒等)不能与其它元器件相碰,不能紧贴印制线、焊盘,其间距应大于2mm。定位孔、紧固件安装孔、椭圆孔及板中其它方孔外侧距板边的尺寸大于3mm。 

7. 发热元件不能紧邻导线和热敏元件;高热器件要均衡分布 

8. 电源插座要尽量布置在印制板的四周,电源插座与其相连的汇流条接线端应布置在同侧。特别应注意不要把电源插座及其它焊接连接器布置在连接器之间,以利于这些插座、连接器的焊接及电源线缆设计和扎线。电源插座及焊接连接器的布置间距应考虑方便电源插头的插拔。 

9. 其它元器件的布置 所有IC 元件单边对齐,有极性元件极性标示明确,同一印制板上极性标示不得多于两个方向 出现两个方向时,两个方向互相垂直。 

10、板面布线应疏密得当,当疏密差别太大时应以网状铜箔填充,网格大于8mil(或0.2mm)。 

 11、贴片焊盘上不能有通孔,以免焊膏流失造成元件虚焊。重要信号线不准从插座脚间穿过。 

 12、贴片单边对齐,字符方向一致,封装方向一致。 

 13、有极性的器件在以同一板上的极性标示方向尽量保持一致 

       元件布线规则

1.画定布线区域距PCB板边≤1mm的区域内,以及安装孔周围1mm内,禁止布线 

2.电源线尽可能的宽,不应低于18mil;信号线宽不应低于12mil; cpu入出线不应低于10mil(或8mil);线间距不低于10mil 

3、 正常过孔不低于30mil 

4、 双列直插:焊盘60mil,孔径40mil 1/4W电阻: 51*55mil(0805表贴);直插时焊盘62mil,孔径42mil 无极电容: 51*55mil(0805表贴);直插时焊盘50mil,孔径28mil 

5、 注意电源线与地线应尽可能呈放射状,以及信号线不能出现回环走线

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