Ball Grid Array (BGA)

Ball Grid Array (BGA) is a surface-mount package that utilizes an array of metal spheres or balls providing external electrical interconnection. The balls are composed of solder, and are attached to a laminated substrate at the bottom side of the package. The die of the BGA is connected to the substrate either by wire bonding or flip chip connection. The substrate of a BGA has internal conductive traces that connect the die-to-substrate bonds to the substrate-to-ball array bonds.

PBGA

The wire-bonded PBGA (Plastic Ball Grid Array) package is an excellent package for mid- to high-performance devices that require low inductance, ease of surface mounting, relatively low cost, and excellent package reliability. Additional copper layers in the substrate allow for increased power dissipation capability with the Thermally Enhanced PBGA (TEPBGA).

Features:

• Custom substrate designs / ball maps for maximum routing flexibility and electrical performance Custom ball patterns / full arrays / depopulated arrays available Substrates use standard organic PCB manufacturing technology Two or four layer substrates available (ground / power planes) Proven reliability in automotive / industrial environments Capability to withstand lead-free reflow processes (260°C reflow)
• Lead-free solder balls available (95.5% Sn, 4% Ag, 0.5% Cu

TBGA

The TBGA (Tape Ball Grid Array) is a mid to high end BGA packaging solution for applications needing excellent thermal performance without an external heatsink.

Features:

• Improved thermal performance over std PBGA packages <15°c/watt style="font-size: 10pt;">Custom substrate designs / ball maps for maximum flexibility and electrical performance Custom ball patterns / full array / depopulated arrays available; 1.0 mm to 1.27 mm pitch Substrates use standard PCB manufacturing technology Maximum thickness from 1.30 mm to 1.60 mm

• Fine Lines/Spacing Geometry (35/35 μm) on two sides of polyimide substrate

  
  

Ball Shear

The ball shear test is another test to measure the wire bond strength at the first bond through the horizontal shear force. A bond shear tester is required in performing the test which consists of:

1) A shearing arm with a chisel-shaped tool at the end
2) An instrument for measuring the shear strength of the bond

The procedure consists of positioning the shearing tool just beside the ball bond to be tested and slightly above the surface of the first bond pad, then move the tool horizontally against the ball, in effect pushing the ball off its bond pad. The bond shear force is then measured by the ball shear tester in gram-force. The failure modes for ball shear test are as shown below:

1) Ball lifting
2) Ball shear
3) Pad lifting

Figures below show the illustration for ball shear testing and the result of ball shear.

the shear tool's position

the first bond pad showing normal ball shear

the second bond pad showing ball lift

Wire Peel

Wire peel test is a test for wire bond strength at the second bond. It consists of applying an upward force under the wire at the second bond post, pulling the wire away from the bond post. The same wire pull tester is used in performing the test. The failure mode for wire peel test is almost same with wire pull test as shown below:

1) Ball bond lifting
2) Break at stitch
3) Center wire break
4) Second bond or wedge bond lifting

Figures below show the illustration for wire peel testing and the result of break at stitch and wedge lifted.

tool's position

break at stitch

wedge lift

Wire Pull

Wire Pull Test:

Wire pull test is a test for wire bond strength and quality at the first bond. It consists of applying an upward force under the wire to be test, and effectively pulling the wire away from the die. Wire pull tester is required in performing the test, which consists of two parts:
1) A pull hook which is used for applying the upward pulling force on the wire
2) An instrument for measuring the force at which the wire or bond fails. The force is recorded in gram-force.

The procedure consists of applying the pull hook under a wire at the first bond and it’s positioned at the highest point along the loop of the wire, and pulling the wire away from the die through the vertical pull force perpendicular to the die surface. Besides the bond strength, I had to record the bond failure mode as well. The failure mode refers to one of the following:
1) Ball bond lifting
2) Break at neck
3) Break at stitch or heel break
4) Center wire break
5) Pad lifting

wire pull tool's position

ball lift

pad lift