ASTM International

Standard Practice for Nondestructive Pull Testing of Wire Bonds
 N F458

Annotation

This practice covers nondestructive testing of individual wire bonds made by either ultrasonic, thermal compression or thermosonic techniques. The test is intended to reveal (by breaking) nonacceptable wire bonds but is designed to avoid damage to acceptable wire bonds.

NOTE 1-Common usage at the present time considers the term "wire bond" to include the entire interconnection: both welds and the intervening wire span.

The practice covers wire bonds made with smalldiameter (from 0.0007 to 0.003-in. (18 to 76- m)) wire such as the type used in integrated circuits and hybrid microcircuits, system in package, and so forth.

This practice can be used only when the loop height of the wire bond is large enough to allow a suitable hook for pulling to be placed under the wire.

While the procedure is applicable to wire of any composition and metallurgical state, criteria are given only for gold and aluminum wire.

A destructive pull test is used on wire bonds of the same type and geometry to provide the basis for the determination of the nondestructive pulling force to be used in this practice. This may only be used if the sample standard deviation, s, of the pulling forces required to destroy at least 25 of the same wire bonds tested by the destructive pull-test method is less than or equal to 0.25 of the sample average, x-. If s > 0.25 x-, this practice may not be used.

NOTE 2-If s > 0.25 x-, some aspect of the bonding process is out of control. Following corrective action, the destructive pull-test measurements should be repeated to determine if the s < 0.25 x- criterion is met.