Defect free assembly of SMT devices

Process control is the only way to achieve defect free soldering. Soldering is a simple and repeatable process which is easily controllable. Inspection is less than 70% effective and cannot guarantee joint quality. Reworking and touch-up always reduces the life of solder joints. Inspection and reworking add nothing to the value of the product. A correctly set-up machine can never cause defective joints if PCBs and components are meeting solderability specifications. Solderability has a finite life usually of not more than six months. The PCB manufacturers shop is nothing but an extension to a manufacturing shop. Process control during bare PCB manufacturing results in good solder quality. Dewetting or nonwetting is usually caused by poor solderability of PCB or components. Blow holes indicate that there is a lack of control in a PCB fabrication process. Pin holes in solder joints indicates that the board manufacturer should review his drilling, hole cleaning and plating process. Touch up has no relation with reliability improvement of solder joints, it improves only cosmetics