The main reasons for PCB delamination or “popcorning” are primarily (1) moisture absorption and (2) excessive α2/Z-axis CTE (Coefficient of Thermal Expansion). Among these, moisture absorption is responsible for about 70% of delamination issues. Other factors, such as uneven thermal expansion, inconsistent cooling and heating, mechanical damage during processing, or poor oxidation treatment, can also contribute—but their impact is generally much lower.
Recently, some people have asked about issues with solder empty in small chip SMD components like resistors and capacitors. Even after thoroughly checking the reflow oven profile settings and confirming everything is correct, solder empty still frequently occur with these components, often in fixed positions. Observations of the solder also don’t show any signs of non-wetting or de-wetting, leaving many puzzled.
In reality, the cause of solder empty in these components isn’t that hard to understand! It’s essentially the same reason tombstoning occurs. To put it simply, it all comes down to this: “The solder paste on the two terminal ends of the component melts at different times, resulting in uneven forces and causing one side to lift.”
With the rapid adoption of smartphones, the trend toward miniaturized electronic products, and the EU’s requirements for lead-free manufacturing, Electroless Nickel Immersion Gold (ENIG) surface treatment PCB has become a popular choice for many electronic products. This is largely due to its simplicity and lower cost compared to other surface treatments, as well as its numerous advantages, including:
This is a summary post aimed at providing some guidance to newcomers in the electronics assembly field on methods for analyzing the solderability of BGA (Ball Grid Array) solder balls. Workingbear decided to write this after seeing someone ask about this topic in an online forum. Some of the content might overlap with topics already covered in previous blog posts.
Workingbear recently received questions from readers about electronic component soldering leads turning yellow or showing discoloration (purple, blue, etc.) after going through the reflow oven. Why do the leads of components discolor after reflow? Does this discoloration affect product functionality? And how should we handle discolored components or assembled PCBs? Let’s dive into these questions for this article.
