1、DFM鋼網&PCB設計電信學院電子工藝與管理1SMT印刷工序中的DFM影響到印刷的設計因素：PCB的焊盤設計不同元器件所選用的開孔現狀和尺寸不同焊點所需焊料量同一PCB上的開孔尺寸差鋼網設計鋼網厚度鋼網的加工方法鋼網開孔2鋼網設計鋼網厚度鋼網的加工方法鋼網開孔34鋼網設計要求鋼網開孔設計：寬厚比1.5面積比0.66開孔尺寸：焊盤尺寸J型和翼型引腳0.41.3mm pitch開孔寬度焊盤寬度（0.030.08mm）PBGA開孔直徑焊盤直徑0.05mmCBGA開孔直徑焊盤直徑（0.050.08mm）56QFP器件的引腳間距與鋼網厚度加工對象引腳中心距/mmPCB焊盤寬度/mm鋼網厚度/mmQFP0

2、.650.330.15QFP0.50.250.15QFP0.30.150.17開孔焊盤開孔焊盤開孔焊盤圓弧貼片阻容元件鋼網開孔8MELF和印膠鋼網開孔MELF印膠開孔焊盤除此兩處之外其他均為圓角印膠開孔焊盤印膠鋼網厚度一般為：0.150.2mm開孔位置：元件兩焊盤中心開孔寬度：1/3的焊盤內邊距開孔長度：110的焊盤寬度鋼網開孔尺寸應該與元件的具體尺寸一致。910工藝邊和定位孔識別標志定位孔：用于機械定位要求：孔壁光滑，不要有涂覆層；周圍2mm內無銅箔工藝邊：一般為58mm組裝過程中設備夾持所需的距離工藝邊內不可以布元器件11Fiducial Mark常用標識：作用：定位、位置校正設置原則：P

3、CB定位時：至少需要兩個應不對稱設置？元器件定位時：僅針對貼片江都要求高的元器件？置于元器件對角上12拼板設計？拼板的連接方式？拼板的工藝邊？拼板的定位孔？拼板的mark點13元器件方向設計14焊盤與導線關系xx15元器件之間的間隙？1617Resistor Pad Design18Resistor Pad Design19Resistor Pad Design20SOT23 Pad Design21SOT23 Pad Design22SOT23 Pad Design23IC Pad Design24Electrical assembly types2526Examples of typica

4、l package styles and package descriptive designators27Lead-form (or terminal-shape) examples28Pro examples29Example of C1206 capacitor dimensioning for optimum solder fillet conditions30Pro of a gullwing leaded SOIC31Recommended minimum land-to-land clearances32Component orientation for wave solder

5、applications33Alignment of similar components34Fiducials 35Fiducial types for vision systems & clearance requirements36Fiducial locations on a printed circuit board37Land pattern to via relationships38Examples of via positioning concepts39Vias under components40Conductor characteristics41Examples of

6、 modified landscapes42Typical copper glass laminate panel43Conductor clearance for V-groove scoring44Breakaway (routed pattern)45Routed slots46Gang & Pocket solder mask window47Component temperature limits48General description of process validation contact pattern and interconnect49Photo image of IPC-A-49 test board for primary side50Flat ribbon, L, and gullwing lead joint description51Round or flattened (coined) lead joint description52Test via grid concepts53General rel