Standards Development

Scope

This test method provides a means for determining the strength and failure mode of a wire bonded to, and the corresponding interconnects on, a die or package bonding surface and may be performed on unencapsulated or decapsulated devices.  This test method may be performed on gold alloy, copper alloy, and silver alloy thermosonic (ball and stitch) bonds made of wire ranging in diameter from 15 µm to 76 µm (0,000 6” to 0,003”); and on gold alloy, copper alloy, and aluminium alloy ultrasonic (wedge) bonds made of wire ranging in diameter from 18 µm to 600 µm (0,000 7” to 0,024”)This wire bond pull test method is destructive.  It is appropriate for use in process development, process control, and/or quality assurance.

This test method allows for two distinct methods of pulling wires:

1)      One method incorporates the use of a hook that is placed under the wire and is then pulled.

2)      One method requires that after the wire be cut, a clamp is placed on the wire connected to the bond to be tested, and this clamp is used to pull the wire.

This test method defines three pull tests.  The Wire Pull Test (WPT) is appropriate for all bonded wires.  The Ball Pull Test (BPT) and Stitch Pull Test (SPT) are appropriate for thermosonically bonded wires.

This test method can also be used on the following four applications of thermosonic and ultrasonic bonds, though each requires special considerations when performing the test method:

a)      Pulling aluminium wires and aluminium ribbons that are bonded with multiple ultrasonic bonds.  See 5.3.2.2.2 for special considerations.  Multiloop wires and ribbons are used in some high-power device packages.

b)      Pulling wires of reverse bonds which are also known as “stitch on ball”.  These types of bonds can include gold stitch on gold ball, copper stitch on copper ball, and copper stitch on gold ball.  See Clause A.1 in Annex A for additional information.

c)      Pulling a thermosonically bonded wire that has a security bond (see 3.9) or security loop (see 3.19) placed on top of the stitch bond (see 3.3) in order to provide additional strength.  See Clause A.2 for additional information.

d)      Pulling thermosonic wire bonds on stacked die when wires and/or bonds are not accessible to allow for proper pull testing.  See 5.3.2.2.4 for special considerations

This test method does not include bond strength testing using wire bond shear testing. Wire bond shear testing is described in IEC 60749-22-2, Bond strength testing – Wire bond shear test methods.