IEC 60749-22:2002 pdf download

IEC 60749-22:2002 pdf download.Semiconductor devices – Mechanical and climatic test methods -Part 22: Bond strength.
2.2 General description of the test
2.2.1 Method A: Wire pull (applied to bonds separately)
The wire connecting the die or substrate should be cut so as to provide two ends accessible for a pull test. In the case of short wire runs, it may be necessary to cut the wire close to one termination in order to allow the pull test at the opposite termination. The wire should be gripped in a suitable device and simple pulling action applied to the wire or to the device (with the wire clamped) in such a manner that the force is applied within 5° of the parallel to the surface of the die or substrate in the case of a stitch bond.
2.2.2 Method B: Wire pull (applied to two bonds simultaneously)
A hook should be inserted under the lead wire connecting the die or substrate to the terminal, and a pull applied to the hook with the device clamped. The pulling force is applied approximately in the middle of the wire in a direction within 50 of the normal to the die or substrate surface or normal to a straight line between the bonds.
2.2.3 The pulling force should be progressively increased until the wire or a bond breaks (item a) in 2.2.4) or until the minimum force has been reached (item b) in 2.2.4).
2.2.4 Failure criteria
a) For determining acceptance, the value of the pulling force at which the wire or bond breaks should be recorded and compared with that given In table 2 (see note).
For wire diameters not specified in table 2. the curves of figure 3 should be used to determine the bond pull limit. The curves are only applicable to bond pulls normal to the die.
b) As an alternative procedure, the pulling force is increased to the specified minimum value (see note). If neither the wire nor the bond is broken, the bond is considered to have passed the test.
NOTE The pulling force should be modified where relevant (for example, for method B) by using the information given in the annex.
2.2.5 Classification of failures
When specified, broken wires or bonds should be classified as follows:
a) wire break at neckdown point (reduction of section due to bonding process);
b) wire break at a point other than neckdown;
C) failure in bond (interface between wire and metallization) at the die;
d) failure in bond (interface between wire and metallization) at substrate, package post or any point other than at the die;
e) metallization lifted from the die;
f) metallization lifted from the substrate or package post;
g) fracture of the die;
h) fracture of the substrate.
NOTE Method B is not recommended for the purpose of measuring the absolute value of the bond strength (see annex A). However, it may be used for testing the bond quality on a comparative basis during the manufacturing process.
3 Method C
3.1 Scope
This test is normally intended to be applied to bonds external to the device package.
3.2 Method C: Bond peel
The lead or terminal and the device package should be gripped or clamped in such a manner that a peeling stress is exerted with the specified angle between the lead or terminal and the board or substrate. Unless otherwise specified, an angle of 90° should be used.
3.3 The pulling force should be progressively applied until the lead (or terminal) or the bond breaks (see 3.4.1) or until the minimum force has been reached (see 3.4.2).
3.4 Failure criteria
3.4.1 For determining acceptance, the value of the pulling force at which the bond breaks should be recorded and compared with that given in table 2. For wire diameters not specified in table 2, the curves of figure 3 should be used to determine the bond pull limit. The curves are only applicable to bond pulls normal to the die. The result of the test is valid only if the bond itself is the first to fail when the pulling force is applied. Only instances in which the bond itself breaks shall be counted as failures.
3.4.2 As an alternative procedure, the pulling force is increased to the specified minimum value. If neither the lead (or terminal) nor the bond is broken, the bond is considered to have passed the test.
3.5 Classification of failures
When specified, broken leads (or terminals) or bonds should be classified as follows:
a) lead (or terminal) break at a deformation point (weld affected region);
b) lead (or terminal) break at a point not affected by the bonding process;
C) failure in the bond interface (in the solder, or at a point of weld interface between the lead (or terminal) and the board or the substrate conductor to which the bond was made);
d) conductor lifted from the board or substrate;
e) fracture within the board or substrate.