In PCB mass production, surface finishing is one of the critical process areas affecting solderability, appearance, electrical performance, and long-term reliability. Common defects such as pad oxidation, poor solderability, uneven coating thickness, gold layer peeling, discoloration, and corrosion are often related not only to individual process failures but also to…

DFM (Design for Manufacturability) review is an essential step before a multilayer PCB enters production. Among the most common DFM issues are problems related to the solder mask layer. A PCB may perform normally during prototyping but develop solder mask blistering, ink peeling, opening misalignment, or solder mask bridge failure…

During multilayer PCB mass production, solder mask defects can appear in large numbers, including blistering, delamination, ink peeling, pinholes, cracking, and localized exposed copper. When these problems occur, it is tempting to immediately blame the solder mask ink or the PCB manufacturer. However, solder mask failure is rarely caused by…

A high-speed server PCB can pass signal integrity simulation and still experience unexpected failures during laboratory testing. One common cause is power plane resonance, which can create localized voltage fluctuations in the power distribution network (PDN) and indirectly disturb high-speed signal paths. During the debugging of an 8-layer server board,…

During an EMI interference investigation for a power electronics PCB, a noticeable emission increase was observed around 300 MHz. Cross-sectional analysis revealed a small copper area on an inner layer that was electrically floating and positioned very close to an adjacent signal trace. This type of structure is often overlooked…

In high-density PCB assemblies, removing copper beneath a BGA package is sometimes considered a way to improve solder-joint reliability or provide more routing space. However, copper removal does not automatically improve thermal performance. In many cases, the result depends on where the copper is removed, which layers are affected, and…

As PCB operating frequencies continue to increase, material stability becomes increasingly important. This is especially true for 6G PCB designs, millimeter-wave radar, high-speed communication equipment, and other RF applications where even small changes in dielectric properties can affect impedance, phase, insertion loss, and overall system performance. After reflow or other…

Microcracks formed during PCB lamination may remain invisible immediately after manufacturing but gradually develop under repeated thermal cycling. This is particularly important for multilayer PCBs with BGA packages, where differences in thermal expansion between copper, laminate, prepreg, and package structures can create repeated mechanical loading. For example, after thermal cycling…

When a differential pair suddenly crosses a discontinuity in its reference plane—for example, a split plane, a thermal pad clearance, a power-island boundary, or a large void in an internal reference layer—the electromagnetic field around the transmission path can change significantly. This discontinuity can increase coupling to adjacent traces and…

Large-area copper voids in a PCB ground plane may appear to save material, reduce capacitance, improve manufacturability, or accommodate thermal and mechanical requirements. However, in high-speed and RF designs, excessive voiding can significantly change the electrical behavior of the reference structure. A continuous ground plane provides a low-impedance return path…