14.Component Lifted-Spot Reflow( 零件浮起 )

                拒收                        良好狀況

缺點描述 :

Components have been lifted from its original intended position after spot reflow.

過完迴焊後零件自原來焊接位置浮起

可能因素 :

• Conveyor vibration
• 輸出帶震動
• Conveyor angle high
• 輸送帶有角度差
• Early removal of board
• 太早移動板子
• Component not seated right
• 零件未放置到定位
• Improper board handling
• 基板操作不當

可行的預防方法 :

• Maintain the conveyor so as to prevent it from vibrating by removing debris
• 維護輸送帶避免熔錫後震動
• Ensure that the conveyor angle is at the correct level 
• 確保輸送帶無明顯角度差
• Ensure that the board is placed evenly before soldering
• 確保迴焊前是被平穩放置
• Correct preheating should reduce the thermal shock and also ensure a good joint
• 正確的預熱可減少熱衝擊並形成良好接點
• Correct weight of placement should be ensured
• 確好零件重量能抗衡錫點內聚力

重工注意事項 :

• For multilead, fine-pitch component and IC :
  The footprint of the lifted gullwing legs is fluxed and the lifted leg is bent down with the help of a tweezer before the component is soldered back with a chisel-shaped soldering tip.

• For SMD : ( refer to the rework for Tombstone )

For through-hole component :
A desolder is used to remove the solder joint of the lifted leg.A tweezer is used to push the component lifted leg down until it is level and then it is resoldered back.A chisel-shaped soldering tip is used by placing it long enough against the joint such that the transfer of heat is sufficient enough before placing the solderwire close to the tip of the iron.