DFM设计与制造

1、Design For Manufacturing生產方式零件正確選擇板子大小尺寸光學點的需求標示及識別說明資料吃錫的考慮零件方向零件空間距離銅泊,錫墊, 孔徑大小治具孔維修重工測試點折板與連板的考量線路與導通孔測試著想而設計導入工業標準偏 移Pad 設計不良易造成偏移(往吸熱較多處)Component spaceFor wave soldering components, must be spaced sufficiently far apart to avoid bridging. This is less important for reflow soldering but suffici

2、ent space must be allowed to enable rework should it be required.Component spaceFreeAreaTest Pad5.00mmFixture0.5mm MinDepanelizationDefects can still occur much further away from the board edge if the board is large and flexible or if components are perpendicular to stress gradients. Components need

3、 to be isolated from connectors, mounting holes, pots, etc. to minimize damage from those sources of deflection.NGNGComponent OrientationDip FlowOKNG減少 ShortDip Flow增加拖錫點將錫留在特定位置，減少短路避免造成短路盡量將PAD與大銅箔隔離，避免受熱不均Change to1.5 mm採用短腳作業，避免引腳間短路IC Alignment在四邊的PAD加大，利用熔錫時的內聚力作位置校正板彎(1) PCB设计不合理，元件分布不均会造成PCB

4、热应力过大，外形较大的连接器和插座也会影响PCB的膨胀和收缩，乃至出现永久性的扭曲。(2)双面PCB，若一面的铜箔保留过大(如地线)，而另一面铜箔过少，会造成两面收缩不均匀而出现变形。 合理设计PCB，双面的钢箔面积应均衡，在没有电路的地方布满钢层，并以网络形式出现，以增加PCB的刚度，在贴片前对PCB进行预热，其条件是1054h；调整夹具或夹持距离，保证PCB受热膨胀的空间；焊接工艺温度尽可能调低；已经出现轻度扭曲时，可以放在定位夹具中，升温复位，以释放应力，一般会取得满意的效果。避免板彎Add dummy circuitToo many empty area1.利用治具挾持2.增加空銅箔達

5、到熱均勻3.減少V-Cut，以機器切板Fillet Lifting How to avoid:Use silver-rich alloys. Silver contents of 3.5 % are recommended. Process Qualification VoidHow voids are formed:Voids are the result of solder shrinkage during solidification. Poor wetting can case voids.Outgassing in the plated through holes during so

6、ldering may produce holes in the solder.Sources of gas are moisture in the laminate and incomplete curing of the laminate.Incomplete outgassing can be caused by gas from flux chemistry of the solder paste or the flux for wave soldering.Improper amount of solderProcess Qualification Stencil CHIP元件，按1：1开口 P=0.5mm，IC&QFP，开口宽 0.25mm P=0.635mm，IC&QFP，开口宽 0.35mm P0.635mm， IC&QFP， 开口宽为55%PITCH P=0.8mm，BGA ，开0.45mm 的圆。 P=1.27mm，BGA ，开0.7mm 的圆。Lead Fre