As conductor spacing shrinks and overall par sizes become smaller and smaller, conductive anodic filament or CAF testing is becoming even more important to establish the reliability of PCBs and electronic components.

Conductive Anodic Filament (CAF) testing helps to determine the reliability of printed circuit board (PCB) laminate materials or finished PCB products. Conductive anodic filaments form when the presence of an electric field causes electrochemical migration of copper salts across the nonmetallic portions of a circuit board. This can lead to shorting and product failure. Element’s testing experts give you the data you need to understand your product’s properties and limitations.

How CAF Testing is performed on PCBs

CAF testing is performed under high temperature and high humidity environmental conditions, generally using standard test method IPC-TM-650, Method 2.6.25A, with standard coupon designs such as IPC-9253, IPC-9254, IPC-9255, and IPC 9256. Some OEMs employ their own coupon design in place of the standard coupon design, but the coupon designs should include different hole sizes; hole-to-hole, hole-to-plane, or Z-axis spacings; and glass fiber orientations to allow for all possible failure modes.

The IPC-TM-650 Method

For the IPC-TM-650 test method, samples are placed under environmental testing for 596 hours, with a bias voltage applied for the duration of the test, and high-resistance measurements are periodically performed. Experts review the testing data for any large drops or high resistance shorting (≤1.00 x 107Ω). If CAF growth is suspected, we can perform a standard failure analysis within the failed area.

CAF testing is often used as a standalone test, for IPC-4101 qualifications, or as part of OEM specifications.

The Element advantage

CAF testing is just one of the many tests our family of laboratories offers for testing the performance and reliability of your printed circuit boards. You can rely on our decades of expertise and our knowledge of the most pressing challenges in the electronics industry. From materials testing to product certification, Element is your single-source provider for testing, inspection, and certification across the product lifecycle.

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