How To Detect Potential Hidden Faults in PCBA?

Introduction

In the field of electronics manufacturing, one of the most frustrating problems is PCBA that perform perfectly in factory testing but suddenly malfunction after a period of use by customers. These potential hidden faults are like “time bombs” buried inside the product, not only damaging the user experience but also causing fatal damage to the brand’s reputation. Therefore, for high-quality PCBA processing, its value lies not only in producing circuit boards that meet appearance standards, but also in its ability to identify these hidden “killers” through a series of in-depth testing methods.

I. Beyond Conventional Testing: Why Are AOI and ICT Insufficient?

Conventional PCBA manufacturing processes typically include AOI (Automated Optical Inspection) and ICT (In-Circuit Testing). SMT AOI machine excels at detecting component errors, omissions, reversals, and solder joint appearance issues. ICT can identify open circuits, short circuits, and component value errors. However, both have certain limitations:

• AOI only inspects the surface: For components with bottom-side solder joints, such as BGA and QFN, AOI is ineffective. It cannot detect internal defects like bubbles (voids) or micro-cracks within solder joints.
• ICT is a static test: ICT tests components under normal temperature and pressure conditions, unable to simulate the complex environmental conditions PCBA faces in actual operation, such as high temperatures, high humidity, and vibrations. A component that appears “healthy” on the test bench may experience performance drift when temperatures rise, leading to equipment failure.

Therefore, to identify hidden faults, we must employ more in-depth and rigorous testing methods.

II. X-ray: Revealing the Secrets of PCB Internal Soldering

X-ray inspection, particularly 3D AXI (Automated X-ray Inspection), is a powerful tool for detecting internal hidden faults. It is like performing a CT scan on the PCBA, enabling clear visualization of:

• BGA/QFN solder joints: Inspecting for voids, cracks, misalignment, or “head-in-pillow” effects in solder balls. These are common causes of product failure during long-term use.
• Internal circuits of multilayer boards: Check for internal open circuits or short circuits.
• Through-hole filling: Verify that solder filling within through-holes is complete, which is particularly critical for connection points requiring high current carrying capacity.

Through X-ray inspection, many internal soldering defects generated during PCBA manufacturing—which are invisible to the naked eye and conventional equipment—become fully exposed.

III. Stress and aging tests: Simulating real-world “extreme” conditions

The most effective way to identify hidden faults is to “let them reveal themselves.” Stress and aging tests (also known as environmental stress screening, ESS) are based on this principle, accelerating the manifestation of potential defects by simulating extreme operating environments that products may encounter during their lifecycle.

• High-Low Temperature Cycling Test: The PCBA is subjected to rapid alternating high-temperature and low-temperature environments. Due to the differing thermal expansion and contraction coefficients of various materials (such as PCB substrates, components, and solder), this temperature shock applies stress to weak points like cold solder joints and micro-cracks, causing them to fully expose.
• Burn-in Test: The PCBA is powered on and operated continuously under a set high-temperature environment. This effectively screens out electronic components with early failure risks and identifies performance instability issues that may arise under high temperatures.
• Vibration Test: Simulates the vibration environments a product may encounter during transportation or use to verify the solder joint integrity of components and the structural stability of the PCBA.

PCBA that has undergone these rigorous tests will have its long-term reliability greatly enhanced.

IV. Preventing Issues at the Source: The Importance of Process Control

The most effective way to detect faults is to prevent them from occurring in the first place. A top-tier PCBA manufacturing facility not only excels at “treating issues” but also specializes in “preventing issues.” By introducing 3D SPI (solder paste inspection) during production to ensure solder paste printing quality, strictly controlling the reflow soldering temperature curve, and conducting rigorous incoming component inspections, the likelihood of hidden faults can be significantly reduced from the source.

Conclusion

Detecting potential hidden faults in PCBA is a systematic engineering task that requires PCBA manufacturers to possess thinking and capabilities beyond conventional testing. From using X-rays to inspect internal components, to conducting pressure tests to anticipate future issues, to implementing strict process controls to prevent problems before they arise, this comprehensive approach reflects a factory’s commitment to ensuring the long-term reliability of its products. For customers, choosing a partner willing and capable of conducting in-depth fault analysis is the wise choice for ensuring the longevity of their products.

Company Profile

Zhejiang NeoDen Technology Co., Ltd. has been manufacturing and exporting various small pick and place machines since 2010. Taking advantage of our own rich experienced R&D, well trained production, NeoDen wins great reputation from the world wide customers. 

with global presence in over 130 countries, the excellent performance, high accuracy and reliability of NeoDen PNP machines make them perfect for R&D, professional prototyping and small to medium batch production. We provide professional solution of one stop SMT equipment.