SMT Quality Control

 

Bonding

 

1. Nozzle Control

IPA is not so effective to clean up inner part of nozzle, acetone is more recommendable (except clogging bond being untouched for certain hours.) Ultrasonic Cleaning is also recommendable. After cleaning, every inner part of nozzle must be inspected  by micro-scope by lighting-up the inside from bottom. Certainly, we also must check nozzle lacking or transformation, which will cause unstable bonding as well as lacking chip nozzle causes lower mounting rate. Better input firmly the original nozzle shape and performance so as for easier judgment.

2. Bond Control

Keep it in refrigerator, vertically with nozzle-top down. When production is stopped at the half-way, keep it together with nozzle in the refrigerator is still yet to cause any problems. (However, if more than 24 hrs stoppage, nozzle must be removed.)

 ３．Others

Sometimes, we can see a problematic bonding, where the bond spreads wider than the diameter of nozzle and higher than the height of nozzle.

Too much bond taken back by nozzle will
cause shortage of bonding. Or else, it will
become excessive on PCB. Proper nozzles
must be selected by depending on the quantity
and the pitch.
 

                  (NG)

Look at the photo on the left, we must
consider diameter of nozzle and its distance
correctly.  Also, there are types on bonding in
expandable or solid. A parameter fine-tuning
based on each bond type must be taken.
 
 

              (Good)

                       

(Expandable)                           (Solid)

 

 

If the bonding is unstable, machine maintenance or calibration for more than 1 year must be carried out. Regardless of regular calibration, if still the bonding is still unstable, wear & tear of nozzle or O-Ring must be checked. Secondly, bond itself may be deteriorated. As there are many factors have to be considered, field experiment and patience are strictly required.

 

:: Written by Rising Dragon, 29-Dec-2010 ::