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Technical Application Data

This report summarizes the main results of a capability study using SPT Infinity capillary bonded on BGA device for fine pitch bonding application. It includes information pertaining to the data from optical and destructive measurements, SEM pictures of the bonded units and the condition of the used capillary.

Currently tool life: 800K bonds
Targeted tool life: 2400K bonds

   

Bonding Results:

Bonding Responses

 
Bonded Ball Size
 Bonded Ball Height
 Ball Shear Strength  Wire Pull Strength

Bonded Units:

  New Capillary   500K Bonds
  1000K Bonds   2400K Bonds
    Looping Profile @ 2400K Bonds

Observation:

  • As shown above, the tool life study for the infinity capillary reveals that the basic bonding responses for wire pull reading and ball size, height and shear are still within the manufacturing specification at 2400K bonds. The bond deformation for the ball bond is well controlled, which indicates that little load up exists at the chamfer angle and chamfer diameter locations at 2400K bonds (tool life for a standard capillary is 800K bonds). The stitch deformation indicates that the load up at the OR and FA locations is minimal since the profile of the stitch bond maintains its original shape at 2400K bonds. Throughout the entire bonding up till 2400K bonds, only 3 missing ball was detected, which represented a DPM of 1.3. No other capillary related defects were observed.

  • During the looping motion, the wire movement or flow inside the capillary can induce certain amount of contamination that can restrict the wire movement, resulting in tight wire loop or inconsistent loop height, and eventually clog the capillary hole. Hole to wire clearance, consistency of capillary dimensions and internal surface finish, determine the functionality and tool life. Contamination and foreign particles along the capillary wire-path can result in early capillary failure. To determine the load-up amount accumulated inside the capillary, the looping profile after bonding can provide valuable information pertaining to the load-up condition. As shown above, no looping abnormality was observed on all the wires after 2400K bonds. No distortion in the hole was observed under a high power scope at 200X magnification. The load-up inside the capillary is minimal.

  • SEM pictures of the used capillaries show that the load-up on the infinity capillary was much slower.

Non-infinity capillary @ 800K bonds Infinity capillary @ 2400K bonds

Conclusion:

The load-up on the face of the infinity capillary was much slower compared to the standard capillary. Without any change in the bonding parameters, the Infinity capillary was able to achieve 3X tool life of its original without any degradation in the bond quality. Experimental results confirm the capability of the long life capillary to go beyond the current process capability presently in existence. Today, SPT’s Infinity capillary has been implemented successfully at many production lines for different packages and continues to be a popular customer choice.

 
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