Standard Test Methods for Measuring Pull Strength of Microelectronic Wire Bonds - PDF

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Status: ASTM F459 was withdrawn in 2023 with no replacement. Most labs now run destructive wire bond pull tests to MIL-STD-883 Method 2011 (bond strength), or to JEDEC and AEC-Q100 methods that reference it. The non-destructive companion practice, ASTM F458, was withdrawn at the same time. The method below describes the F459 procedure so existing specs that still call it out can be met.

What the Wire Bond Pull Test Measures

A hook is placed under a bonded wire loop and pulled away from the die until the wire or one of its bonds breaks. The peak force (in grams-force) and the failure location show whether the ball and wedge bonds are strong enough and whether the bonding process is under control. F459 covered wires 18–76 µm (0.7–3 mil) in diameter, including aluminum ultrasonic wedge bonds and gold or copper ball and wedge bonds.

Test Setup

• The device is held flat so the pull direction is perpendicular to the die surface

• The hook goes under the loop, typically near mid-span or near the highest point of the loop; hook position changes how the force splits between the two bonds

• The loop must be high enough for the hook to fit under it without touching the die

• Pull at a constant rate; record peak force and failure mode for every wire

Failure Modes to Record

• Wire break at the neck above the ball (first) bond

• Wire break mid-span

• Wire break at the heel of the wedge (second) bond

• Ball or first bond lift from the die pad

• Wedge or second bond lift from the lead or substrate

• Bond pad or metallization lifting from the die

Bond lifts and pad lifts point to a process problem even when the pull force passes the minimum.

Equipment

• Low-force tensile tester with a 10 N load cell or less; dedicated bond testers use load cells of 100 gf or lower

• Fine wire pull hook sized for the wire and loop height

• Device holder; pinch grips for pulling free wire ends or leads

• Stereo microscope for hook placement and failure inspection

• Environmental chamber for testing after thermal aging

Related Standards

• MIL-STD-883 Method 2011 – bond strength (destructive bond pull test)

• ASTM F458 – nondestructive bond pull (withdrawn 2023)

• JEDEC JESD22-B116 – wire bond shear test method

• AEC-Q100-001 – wire bond shear for automotive ICs

ASTM F459 FAQ

Is ASTM F459 still active?

No. ASTM withdrew F459 in 2023 with no replacement. MIL-STD-883 Method 2011 is the most widely used destructive wire bond pull method today.

What wire sizes did F459 cover?

Wires from 18 to 76 µm (0.0007 to 0.003 in) in diameter, including aluminum, gold and copper ball and wedge bonds.

Where should the pull hook be placed?

Under the loop, typically near mid-span or at the top of the loop, with the pull perpendicular to the die. Moving the hook toward one bond loads that bond more heavily.

What load cell do I need for a wire bond pull test?

Wire bond pull forces are usually a few grams to a few tens of grams, so use a load cell of 10 N or less. Dedicated bond testers use cartridges of 100 gf or lower.