13.Leaching( 端子熔化 )

拒收 良好狀況

缺點描述 :

Metallization of the component has disappeared and material of the component’s body visible.

金屬端子熔化零件底材露出來

允收標準 :

Leaching not exceeding 25% of width or thickness is not consider to be a defect.

零件電器特性無影響 , 且融融比率小於 25%

可能因素 :

• Tin component of the solder dissolved the metallization of components
• 焊錫分解零件錫端子
• Immersion time or contact length with solder too long
• 焊接時間久或溫度過高

可行的預防方法 :

• Ensure that the tin component of solder will not dissolve the metallization of components
• 確保零件錫端子不會被焊錫熔解
• Select components with metallization that would not dissolve in the solder
• 慎選端子材質不會被焊錫熔解
• Ensure that the immersion or contact time is not too long
• 確保迴焊溫度與時間不會太大

重工注意事項 :

For SMD :
Preheating is necessary to soften the adhesive joint between the SMD and board so that it is easier to break by twisting when desoldered.A preheat temperature higher that the glass-transition temperature( 60°C / 140°F ~ 80°C / 180°F ) of the adhesive is necessary.The solder joint is desoldered with the help of a chisel-shaped soldering tip and solder wick.The solder wick should be pressed into the corner long enough to let the heat travel into the gap underneath the component so that the solder is sucked out and the damaged component is replaced by another good one.