Why die shear strength matters

The die shear test mainly evaluates the adhesion strength between the die and the substrate. It assesses the reliability of the materials and process steps used to mount the die, and it is a direct measure of packaging quality. The magnitude of the shear force shows whether packaging quality meets the requirement, while the failure location and failure mode help correct problems occurring in the packaging process in good time.

Chip packaging involves many processes and materials. When the die, the adhesive and the substrate are not well bonded - insufficient bond area, incorrect positioning or voids in the bond layer - the problem shows up directly in the shear force level. After routine testing, mechanical, thermal, humidity and electrical stresses can reduce the tensile strength of internal wires, and poor thermal matching or thermal fatigue between die and substrate can create solder voids in the bond, all of which affect device reliability.

For automotive components, die shear stress testing is therefore an essential item for inspection, monitoring and quality control. Even for general commercial components, die shear testing is one of the key items for screening device quality and stabilising processes in a competitive market.

Test method

A load-applying instrument pushes uniformly against one edge of the die with a steadily increasing force, shearing the die in parallel to the substrate. The ability of the die to withstand the applied shear force is observed, and the shear strength value is used to evaluate how firmly the package is bonded.

Test references: GJB 548B, JIS Z 3198-7.

Die shear strength test

Shear strength test curve

Failure criteria

Referring to GJB 548B, a device is considered failed if it does not meet any one of the following criteria:

A. It does not reach the die strength requirement indicated by the 1.0x curve in the figure below.

B. The force required to separate the die from the substrate is less than 1.25 times the minimum strength shown by the 1.0x curve, while the area retaining die attach material residue on the substrate is less than 50% of the bond area.

C. The force required to separate the die from the substrate is less than 2.0 times the minimum strength shown by the 1.0x curve, while the area retaining die attach material residue on the substrate is less than 10% of the bond area.

Die shear strength standard: minimum force versus die attach area

What AEC-Q requires

AEC-Q qualification defines corresponding die shear test requirements for integrated circuit chips, discrete devices, optoelectronic components and passive components. Die shear testing evaluates packaging reliability, and comparing shear strength before and after environmental preconditioning can also be used to assess the stability of changes in the packaging process.

About NTEK

NTEK Group was founded in 2009 and is headquartered in Shenzhen. The group provides quality research and technical services covering R&D verification, inspection and testing, failure analysis, simulation and market access for intelligent connected vehicles, electronic communications and new energy.

NTEK has extensive experience in automotive-grade electronic certification and has helped more than 100 companies pass AEC-Q series certification. Driven by the need of vehicle makers to localise automotive-grade components and supported by the domestic semiconductor industry, NTEK provides comprehensive testing and certification services, applying AEC-Q automotive standards to control the safety and quality of automotive components, supporting the growth of domestic automotive-grade components and adding new momentum to the intelligent vehicle safety system.