Triaxial Strain Rosette Signal Analysis for In-Circuit Test Fixture Qualification
Triaxial strain rosette signal analysis qualifies ICT fixtures by resolving multi-axis strain rates against IPC/JEDEC-9704 limits to prevent solder cracking.
Substrate Flexure Verification
Bending Test
Mechanical testing standards evaluate the ability of a circuit board to withstand physical bending forces without cracking its copper traces or solder joints. A thorough substrate flexure verification prevents assembly failures caused by board flexing during panelization or chassis installation. This test evaluates the robustness of both the raw laminate and the mounted components under realistic deflection scenarios.
It is critical for assemblies that contain large ceramic capacitors or ball grid array packages.
Deformation Method
The physical test procedure utilizes a multi-point bending fixture to apply a controlled deflection to the center of a supported board while monitoring its electrical continuity. Strain gauges are attached to the board surface near critical components to record the maximum strain generated during the bending cycle. These strain values are compared against maximum allowable limits to ensure that the assembly does not experience structural damage.
If the board flexes beyond the allowed strain threshold, the component layout or the mounting point positions must be revised to reduce the localized bending stresses.
Acceptance Parameter
Excessive strain levels during testing can cause internal microcracking in multi-layer ceramic capacitors, which may lead to short circuits later in the product life. This risk defines the maximum deflection limit for the test procedure, beyond which the evaluation becomes destructive. Consequently, the test must be carefully designed to stay within the safe elastic limits of compliant components.